74917 Community-Based Landslide Risk Reduction Community-Based Landslide Risk Reduction Managing Disasters in Small Steps Malcolm G. Anderson Elizabeth Holcombe Washington, DC © 2013 International Bank for Reconstruction and Development / The World Bank 1818 H Street NW, Washington DC 20433 Telephone: 202-473-1000; Internet: www.worldbank.org Some rights reserved 1 2 3 4 16 15 14 13 This work is a product of the staff of The World Bank with external contributions. Note that The World Bank does not necessarily own each component of the content included in the work. The World Bank therefore does not warrant that the use of the content contained in the work will not infringe on the rights of third parties. The risk of claims resulting from such infringement rests solely with you. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of The World Bank, its Board of Executive Directors, or the governments they represent. The World Bank does not guarantee the accuracy of the data included in this work. The boundaries, colors, denominations, and other information shown on any map in this work do not imply any judgment on the part of The World Bank concerning the legal status of any territory or the endorsement or acceptance of such boundaries. Nothing herein shall constitute or be considered to be a limitation upon or waiver of the privileges and immunities of The World Bank, all of which are specifically reserved. Rights and Permissions This work is available under the Creative Commons Attribution 3.0 Unported license (CC BY 3.0) http://creativecommons.org/ licenses/by/3.0. Under the Creative Commons Attribution license, you are free to copy, distribute, transmit, and adapt this work, including for commercial purposes, under the following conditions: Attribution—Please cite the work as follows: Anderson, Malcolm G., and Elizabeth Holcombe. 2013. Community-Based Landslide Risk Reduction: Managing Disasters in Small Steps. Washington, D.C.: World Bank. doi:10.1596/978-0-8213-9456-4. License: Creative Commons Attribution CC BY 3.0 Translations—If you create a translation of this work, please add the following disclaimer along with the attribution: This translation was not created by The World Bank and should not be considered an official World Bank translation. The World Bank shall not be liable for any content or error in this translation. All queries on rights and licenses should be addressed to the Office of the Publisher, The World Bank, 1818 H Street NW, Washington, DC 20433, USA; fax: 202-522-2625; e-mail: pubrights@worldbank.org. ISBN (paper): 978-0-8213-9456-4 ISBN (electronic): 978-0-8213-9491-5 DOI: 10.1596/978-0-8213-9456-4 Cover photo: © iStockphotocom/luoman; cover design: Drew Fasick Library of Congress Cataloging-in-Publication Data Anderson, M. G.
  Community-based landslide risk reduction : managing disasters in small steps / Malcolm G. Anderson, Elizabeth Holcombe.
       p. cm.
  Includes bibliographical references and index.
  ISBN 978-0-8213-9456-4 — ISBN 978-0-8213-9491-5 (electronic)
 1.  Landslide hazard analysis. 2.  Landslides—Risk assessment.  I. Holcombe, Elizabeth. II. Title. 
  QE599.2.A53 2013
 363.34'9—dc23 
                                                                             2012030220 Contents PREFACE xxi ACKNOWLEDGMENTS xxxiii ABOUT THE AUTHORS xxxv ABBREVIATIONS xxxvii 1 FOUNDATIONS: REDUCING LANDSLIDE RISK IN COMMUNITIES 1 1.1 Key chapter elements 1 1.1.1 Coverage 1 1.1.2 Documents 1 1.1.3 Steps and outputs 2 1.1.4 Community-based aspects 2 1.2 Getting started 2 1.2.1 Briefing note 2 1.2.2 What is unique about MoSSaiC? 5 1.2.3 Guiding principles 6 1.2.4 Risks and challenges 6 1.3 Disaster risk: context and concepts 7 1.3.1 Global disaster risk 7 1.3.2 Disaster risk management 11 1.3.3 Recent influences on disaster risk management policy and implications for MoSSaiC 14 1.3.4 Landslide risk and other development policy issues 23 1.4 MoSSaiC 25 1.4.1 Overview 25 1.4.2 MoSSaiC: The science basis 26 1.4.3 MoSSaiC: The community basis 29 1.4.4 MoSSaiC: The evidence base 34 1.4.5 MoSSaiC project components 34 1.4.6 MoSSaiC pilots 35 1.5 Starting a MoSSaiC intervention 42 1.5.1 Define the project scale 42 1.5.2 Define the project teams and stakeholders 42 v 1.5.3 Adhere to safeguard policies 45 1.5.4 Establish a project logframe 45 1.5.5 Brief key leaders 47 1.6 Resources 48 1.6.1 Who does what 48 1.6.2 Chapter checklist 48 1.6.3 References 48 2 PROJECT INCEPTION: TEAMS AND STEPS 55 2.1 Key chapter elements 55 2.1.1 Coverage 55 2.1.2 Documents 55 2.1.3 Steps and outputs 56 2.1.4 Community-based aspects 56 2.2 Getting started 56 2.2.1 Briefing note 56 2.2.2 Guiding principles 57 2.2.3 Risks and challenges 57 2.2.4 Adapting the chapter blueprint to existing capacity 58 2.3 Establishing the MoSSaiC Core Unit 60 2.3.1 Rationale 60 2.3.2 MCU roles and responsibilities 62 2.3.3 MCU membership 65 2.4 Identifying the government task teams 65 2.4.1 Mapping task team 67 2.4.2 Community liaison task team 67 2.4.3 Landslide assessment and engineering task team 68 2.4.4 Technical support task team 69 2.4.5 Communications task team 69 2.4.6 Advocacy task team 69 2.5 Identifying the community task teams 71 2.5.1 Community residents 71 2.5.2 Construction task team 73 2.5.3 Landowners 73 2.6 Integration of MoSSaiC teams and project steps 74 2.6.1 Team structure and reporting lines 74 2.6.2 Integrating teams with project steps 74 2.6.3 Establishing a user group community 75 2.7 Resources 78 2.7.1 Who does what 78 2.7.2 Chapter checklist 79 2.7.3 References 79 3 UNDERSTANDING LANDSLIDE HAZARD 81 3.1 Key chapter elements 81 3.1.1 Coverage 81 3.1.2 Documents 81 3.1.3 Steps and outputs 82 3.1.4 Community-based aspects 82 v i   CO N T E N T S 3.2 Getting started 82 3.2.1 Briefing note 82 3.2.2 Guiding principles 83 3.2.3 Risks and challenges 84 3.2.4 Adapting the chapter blueprint to existing capacity 85 3.3 Landslide types and those addressed by MoSSaiC 85 3.3.1 Types of slope movement and landslide material 85 3.3.2 Landslide geometry and features 87 3.3.3 Landslide triggering events: Rainfall and earthquakes 87 3.3.4 Slope stability over time 91 3.4 Slope stability processes and their assessment 93 3.4.1 Landslide preparatory factors and triggering mechanisms 93 3.4.2 Overview of slope stability assessment methods 93 3.4.3 GIS-based landslide susceptibility mapping 95 3.4.4 Direct landslide mapping 97 3.4.5 Empirical rainfall threshold modeling 98 3.4.6 Physically based slope stability modeling 99 3.5 Slope stability variables 101 3.5.1 Rainfall events 101 3.5.2 Slope angle 103 3.5.3 Material type and properties 104 3.5.4 Slope hydrology and drainage 107 3.5.5 Vegetation 108 3.5.6 Loading 111 3.6 Scientific methods for assessing landslide hazard 112 3.6.1 Coupled dynamic hydrology and slope stability models 113 3.6.2 Resistance envelope method for determining suction control 116 3.6.3 Modeling the impact of small retaining walls 117 3.7 Resources 119 3.7.1 Who does what 119 3.7.2 Chapter checklist 120 3.7.3 Rainfall thresholds for triggering landslides 120 3.7.4 CHASM principle equation set 120 3.7.5 Static hydrology retaining wall stability analysis 122 3.7.6 References 123 4 SELECTING COMMUNITIES 129 4.1 Key chapter elements 129 4.1.1 Coverage 129 4.1.2 Documents 129 4.1.3 Steps and outputs 130 4.1.4 Community-based aspects 130 4.2 Getting started 130 4.2.1 Briefing note 130 4.2.2 Guiding principles 131 4.2.3 Risks and challenges 131 4.2.4 Adapting the chapter blueprint to existing capacity 132 4.3 Defining the community selection process 132 4.3.1 Approaches to comparing levels of landslide risk at multiple locations 134 4.3.2 Methods for community selection 136 4.3.3 Roles and responsibilities in community selection 140 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   v i i 4.4 Landslide susceptibility and hazard assessment methods 140 4.4.1 Qualitative landslide hazard assessment: Field reconnaissance and hazard ranking methods 141 4.4.2 Qualitative landslide susceptibility mapping: GIS index overlay methods 146 4.4.3 Semi-quantitative and quantitative landslide susceptibility and hazard mapping methods 149 4.5 Assessing community vulnerability to landslides 151 4.5.1 Field reconnaissance and vulnerability ranking methods 153 4.5.2 GIS-based mapping methods for vulnerability assessment 155 4.6 Assessing landslide risk and confirming community selection 156 4.6.1 Combining the hazard and vulnerability information 157 4.6.2 Confirming selected communities 157 4.7 Preparing a base map for detailed community mapping 159 4.7.1 Useful features 159 4.7.2 Supporting data 159 4.7.3 Sources of spatial data 159 4.8 Resources 161 4.8.1 Who does what 161 4.8.2 Chapter checklist 162 4.8.3 References 162 5 COMMUNITY-BASED MAPPING FOR LANDSLIDE HAZARD ASSESSMENT 165 5.1 Key chapter elements 165 5.1.1 Coverage 165 5.1.2 Documents 165 5.1.3 Steps and outputs 166 5.1.4 Community-based aspects 166 5.2 Getting started 167 5.2.1 Briefing note 167 5.2.2 Guiding principles 168 5.2.3 Risks and challenges 169 5.2.4 Adapting the chapter blueprint to existing capacity 170 5.3 Deciding on how to work within a community 170 5.3.1 Community participation: Principles 170 5.3.2 Community participation: Practices 174 5.3.3 Community knowledge and participation in the mapping process 176 5.4 Community slope feature mapping 178 5.4.1 Hillside scale: Mapping overall topography and drainage 178 5.4.2 Household scale: Mapping the detail 182 5.4.3 Indicators of slope stability issues 185 5.4.4 Finalizing the community slope feature map 187 5.5 Qualitative landslide hazard assessment 188 5.5.1 Landslide hazard assessment for MoSSaiC projects 188 5.5.2 Identify landslide hazard zones 189 5.5.3 Identify the dominant landslide mechanisms 191 5.6 Physically based landslide hazard assessment 191 5.6.1 Models 191 5.6.2 Data for slope stability models 194 v i i i   CO N T E N T S 5.6.3 Using slope stability models 194 5.6.4 Analyzing the role of pore water pressure 198 5.6.5 Uncertainty in physically based landslide hazard assessment 199 5.6.6 Interpreting physically based landslide hazard assessment results 201 5.7 Prioritize zones for drainage interventions 203 5.7.1 Assign a potential drainage intervention to each zone 203 5.7.2 Draw an initial drainage plan 205 5.7.3 Assign priorities to the different zones 206 5.7.4 Sign-off on the map and the proposed intervention 207 5.8 Resources 208 5.8.1 Who does what 208 5.8.2 Chapter checklist 209 5.8.3 References 209 6 DESIGN AND GOOD PRACTICE FOR SLOPE DRAINAGE 213 6.1 Key chapter elements 213 6.1.1 Coverage 213 6.1.2 Documents 213 6.1.3 Steps and outputs 214 6.1.4 Community-based aspects 214 6.2 Getting started 214 6.2.1 Briefing note 214 6.2.2 Guiding principles 215 6.2.3 Risks and challenges 215 6.2.4 Adapting the chapter blueprint to existing capacity 216 6.3 Principles and tools for general alignment of drains 217 6.3.1 Drainage alignment patterns and principles 218 6.3.2 Calculating drain flow and drain dimensions 222 6.3.3 Estimating surface water discharge 223 6.3.4 Estimating the discharge from houses 226 6.3.5 Estimating dimensions for main drains 227 6.3.6 Example to demonstrate intercept drain effectiveness 227 6.3.7 Example to demonstrate the impact of drain channel slope on flow capacity 228 6.3.8 Example to demonstrate the impact of household water 229 6.4 Drain types and detailed alignments 229 6.4.1 Intercept drains 231 6.4.2 Downslope drains 232 6.4.3 Footpath drains 232 6.4.4 Incomplete existing drainage 233 6.4.5 Drains above landslides to stabilize the slope 234 6.4.6 Incorporating debris traps into drain alignment 235 6.4.7 Proposed drainage plan 236 6.5 Drain construction specifications: materials and details 236 6.5.1 Reinforced concrete block drains 238 6.5.2 Low-cost, appropriate technology for drain construction 239 6.5.3 Combining different drain construction approaches 241 6.5.4 Construction design details 242 6.6 Incorporating household water capture into the plan 242 6.6.1 Houses requiring roof guttering 242 6.6.2 Rainwater harvesting 244 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   i x 6.6.3 Gray water capture 246 6.6.4 Connection to the drainage network 247 6.6.5 Hurricane strapping 249 6.7 Signing off on the final drainage plan 250 6.7.1 Drawing the final drainage plan and estimating costs 250 6.7.2 Community agreement 251 6.7.3 Formal approval and next steps 253 6.8 Resources 254 6.8.1 Who does what 254 6.8.2 Chapter checklist 255 6.8.3 Local designs for concrete drains, catchpits, and baffles 255 6.8.4 References 259 7 IMPLEMENTING THE PLANNED WORKS 261 7.1 Key chapter elements 261 7.1.1 Coverage 261 7.1.2 Documents 261 7.1.3 Steps and outputs 262 7.1.4 Community-based aspects 262 7.2 Getting started 262 7.2.1 Briefing note 262 7.2.2 Guiding principles 265 7.2.3 Risks and challenges 265 7.2.4 Adapting the chapter blueprint to existing capacity 266 7.3 Preparing work packages 266 7.3.1 Prepare a bill of quantities 268 7.3.2 Define work packages 271 7.3.3 Prepare a plan for procurement of materials 272 7.3.4 Prepare detailed construction specifications 272 7.3.5 Compile documents for each work package 272 7.4 The tendering process 274 7.4.1 Identifying contractors from the community 274 7.4.2 Briefing potential contractors 274 7.4.3 Evaluating tenders and awarding contracts 276 7.4.4 Contractors and safeguard policies 277 7.5 Implementing the works: on-site requirements 278 7.5.1 Importance of site supervision 278 7.5.2 Beginning construction: Excavation and alignment requirements 279 7.5.3 Ensure that water can enter drains 281 7.5.4 Capture household roof water 282 7.5.5 Connect household water to drains 284 7.6 Implementing the works: good practices 285 7.6.1 Cast concrete in good weather 285 7.6.2 Store materials securely 287 7.6.3 Keep an inventory 287 7.6.4 Provide access for residents 287 7.6.5 Minimize leakage from pipes 288 7.7 Implementing the works: practices to be avoided 288 7.7.1 Wasted materials and no surface water capture 288 7.7.2 Restricted capacity of footpath drains 288 x   CO N T E N T S 7.7.3 Hazardous access for residents 291 7.7.4 Construction detailing notes 291 7.8 Signing off on the completed works 291 7.9 Postconstruction bioengineering 292 7.9.1 What is bioengineering? 293 7.9.2 The effect vegetation on slope stability 293 7.9.3 Vegetation and urban slope management 294 7.10 Resources 297 7.10.1 Who does what 297 7.10.2 Chapter checklist 298 7.10.3 Low-cost appropriate construction methods 298 7.10.4 Questionable or corrupt practices in construction 300 7.10.5 References 301 8 ENCOURAGING BEHAVIORAL CHANGE 305 8.1 Key chapter elements 305 8.1.1 Coverage 305 8.1.2 Documents 305 8.1.3 Steps and outputs 306 8.1.4 Community-based aspects 306 8.2 Getting started 306 8.2.1 Briefing note 306 8.2.2 Guiding principles 307 8.2.3 Risks and challenges 308 8.2.4 Adapting the chapter blueprint to existing capacity 309 8.3 Adoption of change: from risk perception to behavioral change 309 8.3.1 The behavioral change process 309 8.3.2 Understanding stakeholder perceptions 312 8.3.3 Combining knowledge and action 314 8.4 Communication purpose and audience 315 8.4.1 Defining communication purposes and functions 317 8.4.2 Identifying audiences 317 8.5 Forms of communication and project messages 317 8.5.1 Direct communication, consultation, and dialogue 320 8.5.2 Community demonstration sites and show homes 321 8.5.3 Written and visual materials for communities 323 8.5.4 TV, radio, and newspaper coverage 324 8.5.5 Scientific and professional publications 328 8.5.6 Finalizing project messages 329 8.6 Ways of building local capacity 329 8.6.1 For individuals 330 8.6.2 For teams 331 8.6.3 For politicians 331 8.6.4 For communities 332 8.6.5 For all user groups 333 8.7 Finalizing the integrated behavioral change strategy 334 8.7.1 Encouraging adoption of good drain maintenance practices 334 8.7.2 The integrated behavior change strategy 338 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x i 8.8 Resources 340 8.8.1 Who does what 340 8.8.2 Chapter checklist 341 8.8.3 MoSSaiC certification 341 8.8.4 References 342 9 PROJECT EVALUATION 345 9.1 Key chapter elements 345 9.1.1 Coverage 345 9.1.2 Documents 345 9.1.3 Steps and outputs 346 9.1.4 Community-based aspects 346 9.2 Getting started 346 9.2.1 Briefing note 346 9.2.2 Guiding principles 349 9.2.3 Risks and challenges 349 9.2.4 Adapting the chapter blueprint to existing capacity 350 9.3 Data requirements for project evaluation 350 9.3.1 MoSSaiC project evaluation data 350 9.3.2 Community knowledge and project evaluation data 352 9.4 Project outputs: evaluating immediate impact 353 9.4.1 Typical key performance indicators 353 9.4.2 Output key performance indicators for MoSSaiC projects 354 9.5 Project outcomes: evaluating medium-term performance 354 9.5.1 Observed slope stability 355 9.5.2 Rainfall and slope stability information 357 9.5.3 Cracks in houses 358 9.5.4 Surface and subsurface water 360 9.5.5 Drain performance 362 9.5.6 Environmental health benefits 362 9.5.7 Economic appraisal: Project value for money 364 9.5.8 Adoption of good landslide risk reduction practices 367 9.5.9 Development of new landslide risk reduction policies 367 9.5.10 Finalizing the project evaluation process 369 9.6 Addressing landslide risk drivers over the longer term 370 9.6.1 Disaster risk reduction and climate proofing 370 9.6.2 Connecting hazard reduction and insurance 371 9.6.3 Anticipating future disaster risk scenarios 374 9.7 Resources 379 9.7.1 Who does what 379 9.7.2 Chapter checklist 379 9.7.3 Installing crack monitors 379 9.7.4 Installing and using simple piezometers 380 9.7.5 Cost-benefit analysis 381 9.7.6 References 383 GLOSSARY 387 INDEX 393 x i i   CO N T E N T S FIGURES 1.1 Global landslide risk 3 1.2 MoSSaiC premises, vision, and foundations 4 1.3 Number of great natural catastrophes and associated economic losses worldwide, 1950–2010 8 1.4 Normalized losses from U.S. Gulf and Atlantic hurricane damage, 1900–2005 9 1.5 Exposure and fatalities associated with rainfall-triggered landslides, by income class 10 1.6 Global rainfall-triggered landslide fatalities 11 1.7 Disaster risk management options 14 1.8 Societal landslide risk in Hong Kong SAR, China 15 1.9 International advocacy landscape for disaster risk reduction 15 1.10 UN disaster response organizational framework 16 1.11 Benefit-cost ratio for hurricane-proofing prevention measures for houses in Canaries and Patience, St. Lucia 18 1.12 Mitigation benefit-cost ratio for wood frame building in Canaries, St. Lucia, with and without the effect of climate change 19 1.13 Efficiency of risk management instruments and occurrence probability 19 1.14 Evolution of social fund objectives and activities 22 1.15 Population growth and urbanization drivers of landslide risk 24 1.16 MoSSaiC architecture—integrating science, communities, and evidence 27 1.17 Housing stock can reflect community vulnerability 28 1.18 Stakeholder connections in Guatemala City’s precarious settlements, showing how money flows around, but not into, the settlements 30 1.19 Learning from community residents 32 1.20 Effects of prompt and informed action 32 1.21 MoSSaiC components 36 1.22 Typical communities and risk drivers for MoSSaiC interventions 40 1.23 Countries with damages from disasters exceeding 1 percent of GDP 41 1.24 Impact of Hurricane Allen (1980) on the economy of St. Lucia 41 1.25 MoSSaiC is applicable to many locations outside the Eastern Caribbean 41 2.1 Five missions of the MoSSaiC core unit 63 2.2 Mapping team from a national disaster management agency demonstrates GIS software to MCU team leader 67 2.3 Coordinating with Social Development Ministry and community residents on site 68 2.4 Examples of landslide assessment and engineering task team responsibilities 68 2.5 Technical team training course attendees: Sharing and developing expertise across ministries 69 2.6 Aspects of communication 70 2.7 On-site briefing 70 2.8 Media film elected officials during a MoSSaiC project 71 2.9 Funding agency staff on site at initial stage of MoSSaiC project 71 2.10 Aspects of community resident involvement in MoSSaiC 72 2.11 Briefing potential contractors on site after calling for expressions of interest from within the community 73 2.12 Contractor briefs government technical officers on project implemented in his community 74 2.13 Typical MoSSaiC team reporting structure 75 2.14 User group forum activities 75 3.1 Characteristics of rotational and translational slides in predominantly weathered materials 87 3.2 Definitional features of a landslide 88 3.3 Typical surface and subsurface water sources and flow paths associated with unauthorized construction on hillslopes 89 3.4 Rotational and translational landslides 90 3.5 Distribution of seismicity during the 2001 El Salvador earthquakes 91 3.6 Aerial view of earthquake-triggered landslide in Las Colinas, El Salvador, January 13, 2001 91 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x i i i 3.7 Progressive landslide 92 3.8 Postfailure slope stability 93 3.9 Classified spatial factor data 97 3.10 Landslide susceptibility map 98 3.11 Three landslide inventory maps 98 3.12 Global rainfall intensity-duration thresholds 99 3.13 Discretization of a slope into slices to facilitate slope stability calculations 100 3.14 Preparatory factors that can influence slope stability 102 3.15 Hurricane Tomas over the Eastern Caribbean, 2010 103 3.16 An Abney level and its use 104 3.17 Slope benched by resident to build a house 104 3.18 Typical weathering profiles of tropical soils 105 3.19 Weathering profiles 106 3.20 Shear box used to determine soil strength parameters 106 3.21 Exposed soil pipe some 30 cm below the soil surface 106 3.22 Definition of the planimetric contributing area at two locations in a hypothetical landscape 107 3.23 Shallow rotational slip on an 18-degree slope at the foot of an extensive hillside 108 3.24 Common drainage issues in unauthorized communities 109 3.25 Examples of adverse and beneficial effects of vegetation on slopes 110 3.26 Model of post-landslide vegetation succession for the Caribbean 111 3.27 Examples of incremental construction 112 3.28 Examples of reconstruction on former landslide sites 113 3.29 Representation of a slope cross-section for analysis in CHASM software 114 3.30 CHASM representation of a natural hillslope 115 3.31 Outputs from a CHASM simulation 116 3.32 Superimposition of resistance and strength envelopes 117 3.33 Resistance envelope plots 117 3.34 Inadequate retaining wall design 118 3.35 A simple retaining wall geometry used for the retaining wall analysis 122 4.1 Top-down and bottom-up community selection methods 137 4.2 Field reconnaissance 143 4.3 Method for developing a national landslide risk index map for Cuba 149 4.4 Quantitative GIS-based hazard map for Tegucigalpa, Honduras 150 4.5 Resilience of structures depending on construction type 153 4.6 Generating the base map from a topography map and an aerial photo 160 5.1 Access and control over resources in Ethiopia by women and men 173 5.2 Listening to community residents is important 175 5.3 Engaging community representatives and guides in identifying slope features and landslide issues 176 5.4 Discussing slope stability and drainage hazards around residents’ houses 177 5.5 Informal group discussion held at an accessible location 177 5.6 Local community hall used as venue for hearing residents’ views 178 5.7 Community base map and supplementary aerial photograph 179 5.8 Topographic elements to be distinguished and identified in the field 180 5.9 Example of a tropical hillslope profile illustrating common weathering features 180 5.10 Soil depth and stability 180 5.11 Seepage occurring in dry weather conditions where there is no sign of a zone of topographic convergence 181 5.12 Looking for natural and altered slope drainage 182 5.13 Potential landslide hazard driver: Cutting platforms to build houses 183 5.14 Potential landslide hazard driver: Household roof and gray water discharged directly onto slopes 184 5.15 Potential landslide hazard driver: Failure of poorly designed and constructed water storage structure 185 5.16 Evidence of minor slope movement 186 5.17 Cracks in a wall: Past slope instability or poor construction? 186 x i v   CO N T E N T S 5.18 Example of a community slope feature map showing household-level detail 187 5.19 Piped water supplied to unauthorized communities 189 5.20 The qualitative landslide hazard assessment process 190 5.21 Example of a slope process zone map with supporting observations and interpretations 192 5.22 Typical slope selected for stability analysis 195 5.23 Zone E of the example community with two slope cross-sections marked for analysis 196 5.24 Model configuration and predicted location of landslides 197 5.25 Predicted landslide locations and estimated runout 198 5.26 Predicted improvements in the factor of safety for different drainage interventions 198 5.27 Example of heterogeneity in angle of internal friction and cohesion, classified by weathering grade 200 5.28 Number of geotechnical engineers selecting various friction angles as characteristic for a given set of soil strength data 200 5.29 Effect of soil parameter variability on CHASM simulation results 201 5.30 Slope stability modeling workshop for landslide assessment and engineering task team 202 5.31 Complete community-based landslide hazard assessment process for MoSSaiC interventions 204 5.32 Example of an initial drainage plan 205 5.33 Proposed midslope intercept drain alignment 206 6.1 Iterative design process for developing final drainage plan 219 6.2 Idealized hillside drainage plan showing intercept and downslope drains 220 6.3 Generalized alignment for use with top-of-slope intercept drains 220 6.4 Intercept drain built on a slope with few restrictions to alignment 220 6.5 Drain alignment complexities 221 6.6 Network of small intercept drains intercepting surface water along entire uppermost contour of slope 221 6.7 Downslope drain 221 6.8 Drain alignment to minimize surface and immediate subsurface water flow into previously failed material 222 6.9 Drain aligned to intercept surface water and routed around a major preexisting landslide 222 6.10 Drain alignment for site of progressive failure 222 6.11 Iterative process for designing drain alignments and dimensions 223 6.12 Estimating observed drain flows 228 6.13 Impact of drain gradient on flow velocity and discharge 229 6.14 Effect of household water drainage in a typical community 230 6.15 Potential effectiveness of household drainage measures 230 6.16 Drain alignment must be correctly specified in communities 231 6.17 Main cross-slope intercept drain constructed on a 35 degree slope angle 231 6.18 Poor practice: Downslope drain construction begun at top of hillside rather than base of slope 232 6.19 Examples of footpath and footpath drains being constructed simultaneously 233 6.20 Incomplete and damaged drains 234 6.21 Drain construction above a failed slope 235 6.22 Postconstruction maintenance: Keeping drains free of debris 235 6.23 Debris trap in an urban area of Hong Kong, SAR, China 235 6.24 Example of an initial drainage plan 237 6.25 Example of a draft final drainage plan 237 6.26 Rubble wall as part of drain construction 239 6.27 Example of concrete block drain design 239 6.28 Shipping construction material to site can be expensive 240 6.29 Installation of plastic-lined drain 240 6.30 Community innovation and skills at work after project completion 241 6.31 Combination of block drain and low-cost drain 241 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x v 6.32 Number of days slope surface is saturated per year with and without household water capture 242 6.33 Process for incorporating household water capture into the drainage plan 244 6.34 Retrofitting roof guttering 244 6.35 Rainwater harvesting 245 6.36 A system for filtering and purifying water for human consumption 245 6.37 Cost components of small domestic rainwater harvesting system 246 6.38 Capturing gray water from showers and washing machines 246 6.39 Gray water and roof water connections to block drain 247 6.40 Household connections to main drains 248 6.41 Concrete chambers connecting water from multiple houses to a single collection point with an outflow pipe to a main drain 249 6.42 Fragile roof structure 249 6.43 Hurricane strapping ties 250 6.44 Roof hurricane strap 250 6.45 Extracts from a final drainage plan for agreement with stakeholders and sign-off 252 6.46 Community involvement in finalizing the drainage plan 253 6.47 U-channel 256 6.48 Baffle wall junction 256 6.49 Typical debris/sand trap 257 6.50 Stepped channel 258 6.51 Catchpit junction 259 7.1 MCU meeting to agree on responsibilities during construction process 263 7.2 Contractor site meeting 264 7.3 Modifications to roof structure for roof guttering installation 269 7.4 Downpipe installation detail 269 7.5 Roof guttering and downpipe components 270 7.6 Connection of downpipe to drain awaits purchase of a connecting section 270 7.7 Spreadsheet to assist in developing bills of quantities 270 7.8 Confirming with residents connection of households to drains 271 7.9 On-site meetings with potential community contractors 274 7.10 Some issues to address during on-site briefing 275 7.11 Double handling of materials can require temporary storage 276 7.12 Contractor signing on site with implementing agency representative 277 7.13 Importance of training in reducing rework costs 278 7.14 Clear markings help remove issues of ambiguity for site supervisor 279 7.15 Site supervisor is critical to project success and to ensuring good construction practice 279 7.16 Supervision issue: Large numbers of residents engaging with contractors 280 7.17 Example of detailed alignment issue encountered at construction start 280 7.18 Self-cleaning stepped drains 281 7.19 Finished drain wall height same as adjoining ground surface 282 7.20 Weep hole formation 282 7.21 Drain construction providing for eventual connection with gray water pipes 282 7.22 Issues involved in roof repair 283 7.23 Newly installed roof guttering 283 7.24 Household roof water connections to main drains 284 7.25 Concrete connection chambers 285 7.26 Connecting water tank overflow pipes to nearby drains 286 7.27 Examples of drain bases 286 7.28 Providing adequate temporary access to houses during construction 287 7.29 Using sleeving to join drainage pipe sections 288 7.30 Illustrations of frequently overlooked drainage design and construction details 290 7.31 Drain built with inappropriately high sidewalls 290 7.32 Identify maximum drain capacity adjacent to footpath steps 291 7.33 Some construction practices can pose dangers to small children 291 x v i   CO N T E N T S 7.34 Typical development of plant communities under a bioengineering and maintenance program 293 7.35 Lateral root spread 294 7.36 Four vegetation covers typically found on hillsides housing vulnerable communities 296 7.37 Bioengineered slope in Hong Kong SAR, China 296 7.38 Choosing a debris trap location 298 7.39 Welding in-situ and completion of debris trap 299 7.40 Construction of low-cost drain 300 8.1 The Johari Window for increasing common ground and knowledge among stakeholders 313 8.2 Show homes 322 8.3 Meeting invitation and project flier given to community residents at project start 325 8.4 Example of a leaflet or small poster to use in informal conversations with residents 325 8.5 Using posters to convey project messages 326 8.6 Media filming during construction 327 8.7 Opening frame of a MoSSaiC TV documentary 327 8.8 Community surveyor and contractor receive MoSSaiC certification 331 8.9 MoSSaiC training in the Eastern Caribbean 331 8.10 Building team capacity 332 8.11 Combined slope process zone map and initial drainage plan 332 8.12 Building political capacity 332 8.13 Building community capacity 333 8.14 Building regional capacity: In conferences and on site 334 8.15 Unintended consequences of drainage interventions 335 8.16 Absence of building controls can lead to inappropriate construction 336 8.17 Importance of promoting community clean-up days 337 8.18 Debris traps should be installed and cleared regularly 337 8.19 Debris collection and disposal 338 9.1 Links between project objectives and overall project success 347 9.2 Residents showing issues to be addressed by MoSSaiC interventions 353 9.3 Maximum observed flow level in a MoSSaiC drain during Hurricane Tomas 353 9.4 Landslide in an area immediately adjacent to a slope successfully stabilized by a MoSSaiC intervention 356 9.5 Daily and cumulative rainfall with associated return periods for a location in St. Lucia, October 2008 358 9.6 Benchmarking major rainstorms with satellite imagery 360 9.7 Assessing and monitoring structural cracks 361 9.8 Surface and subsurface water undermining stability of house structures 361 9.9 Convergence of water upslope results in slope instability and property destruction on shallow slope 362 9.10 Drain performance 362 9.11 Stagnant water and disease transmission: The health consequences of poor drainage 363 9.12 Laboratory-confirmed dengue hemorraghic fever in the Americas prior to 1981 and 1981–2003 364 9.13 MoSSaiC and mosquito breeding habitats 364 9.14 Dynamics of policy making 368 9.15 Process of strategic incrementalism 369 9.16 Generalized impact of MoSSaiC interventions on reducing the burden of coping 372 9.17 Model used in St. Lucia for hurricane-resistant home improvement program for low-income earners 375 9.18 Hypothetical calculation base for the resource gap 376 9.19 Media recognition of the world’s urban population crossing the 50 percent mark 377 9.20 Conceptual diagram of a scenario funnel 377 9.21 Crack monitoring gauge and crack record charts 380 9.22 Installing piezometers 381 9.23 Components of an integrated model of landslide hazard and risk assessment 382 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x v i i TABLES P.1 Critical questions and decisions addressed in this book xxxi 1.1 The key teams and tasks in MoSSaiC 5 1.2 Categories of catastrophe 9 1.3 Disaster risk management components 13 1.4 Lessons learned from World Bank natural disaster projects 17 1.5 Percentage of owner occupancy, unauthorized housing, and squatter housing by country income group, 1990 25 1.6 The foundations of MoSSaiC 26 1.7 Coping mechanisms deployed by individual residents in vulnerable communities to reduce landslide risk 31 1.8 Value of community engagement 33 1.9 Basic MoSSaiC outputs and outcomes providing evidence for ex ante landslide mitigation 35 1.10 Broad impacts of community-based landslide risk reduction program in St. Lucia and Dominica, 2005–10 35 1.11 MoSSaiC framework 36 1.12 Characteristics of MoSSaiC project locations in the Eastern Caribbean, 2004–10 40 1.13 Magnitudes of scale-up 42 1.14 Issues to consider when scaling up MoSSaiC 43 1.15 Likely stakeholders and their potential involvement in a MoSSaiC intervention 44 1.16 Typical safeguard policy considerations 46 1.17 Example of a logframe format 47 2.1 Key characteristics of highly successful social development projects 57 2.2 Typical landslide risk management project cycle 60 2.3 The active Samaritan’s Dilemma 61 2.4 Landslide risk reduction issues that need to be offset by a policy entrepreneur 62 2.5 Government task team selection factors 66 2.6 Task teams and guidance notes 66 2.7 Summary template of MoSSaiC project teams, steps, and milestones 76 3.1 Typical landslide risk management project steps and associated scientific basis for MoSSaiC 84 3.2 Slope instability classification 87 3.3 Arias intensity and associated landslide categories 91 3.4 Landslide velocity scale 92 3.5 Factors determining slope stability and associated assessment methods 94 3.6 Spatial scales of landslide triggering mechanisms, preparatory factors and anthropogenic influences 94 3.7 Advantages and disadvantages of different forms of landslide susceptibility and hazard assessment 96 3.8 Vegetation influences on slope stability 110 3.9 Units for the parameters used in CHASM 121 3.10 Results of an illustrative standard static hydrology retaining wall stability analysis 123 4.1 Schematic representation of the basic data sets for landslide susceptibility, hazard, and risk assessment 135 4.2 Framework of potential data and analysis methods 138 4.3 Overview of environmental factors and their relevance to landslide susceptibility and hazard assessment 142 4.4 Typical sections of a slope reconnaissance form 144 4.5 Example of a landslide likelihood rating system 145 4.6 Main elements at risk used in landslide risk assessment studies and their spatial representation at four mapping scales 152 4.7 Typical sections of a slope reconnaissance form that relate to vulnerability assessment 154 4.8 Example of a numerical scoring system for landslide damage to houses 155 4.9 Typical components of a locally derived poverty index 156 4.10 Example of a risk rating matrix 157 4.11 Sample justification for community selection 158 x v i i i   CO N T E N T S 5.1 Types of community participation 172 5.2 Checklist for gender-sensitive risk assessment 174 5.3 Hillside scale features to mark on slope feature map 183 5.4 Household-scale contributors to slope instability to mark on slope feature map 185 5.5 Slope instability evidence to mark on slope feature map 187 5.6 Interpreting the influence of surface water infiltration on slope stability for different slope process zones 193 5.7 Quantitative physically based landslide hazard assessment models appropriate for use as part of MoSSaiC 194 5.8 Typical input parameters and their measurement for slope stability analysis 195 5.9 Summary of the physically based landslide hazard assessment process 202 5.10 Illustrative slope process zones and associated potential drainage measures 206 5.11 Illustrative prioritization of different drainage interventions in each of the zones 207 6.1 Calculations for estimating discharge into drains and drain size 224 6.2 Values of runoff coefficient C for the rational method 225 6.3 Drainage alignment summary for use in developing final drainage plan 238 6.4 Construction design details related to aspects of drain alignment 243 6.5 Initial costs for drain construction and for household water connections 251 6.6 Illustrative drawings for drain design 255 7.1 Yardsticks for selected community-based performance measures 265 7.2 Items to include when surveying houses identified for household water capture 269 7.3 Requirements and specifications to be developed for work packages 273 7.4 Illustrative safeguard checklist for contractors 277 7.5 Examples of frequently overlooked drainage design and construction details 289 7.6 Example of an informal schedule of construction defects and outstanding works 292 7.7 Decision aid for choosing a bioengineering technique 295 8.1 Steps in the ladder of adoption and associated MoSSaiC context 311 8.2 Behavior change factors: From motivation to action 312 8.3 Knowledge and action as part of the adoption of the MoSSaiC process 316 8.4 Questions to guide the design of a MoSSaiC communication strategy 316 8.5 Examples of local factors affecting communication 318 8.6 Examples of communication tools by mode, channel, and purpose 318 8.7 Deciding which forms of communication to use for each stakeholder audience 319 8.8 Examples of direct two-way communication tools for use throughout the MoSSaiC project process 320 8.9 Example uses of demonstration sites and show homes during the MoSSaiC project process 322 8.10 Examples of written/visual materials to be used during the MoSSaiC project process 324 8.11 Examples of media coverage during the MoSSaiC project process 327 8.12 Factors for the MCU to consider when commissioning a TV documentary 328 8.13 MoSSaiC capacity requirements at individual, organizational, and institutional levels 330 8.14 Examples of capacity-building tools by learning mode 330 8.15 Mapping the integrated behavioral change strategy 339 9.1 Data needed to evaluate outputs and outcomes by category of evaluation 352 9.2 Typical donor-focused key performance indicators for project outputs 354 9.3 Detailed MoSSaiC key performance indicators for project outputs 355 9.4 MoSSaiC key performance indicators for project outcomes 356 9.5 Landslides reported pre- and post-project with respect to major rainfall events in the Eastern Caribbean 359 9.6 Transmission routes of water-related diseases 363 9.7 Simple questions to help measure MoSSaiC project value for money 365 9.8 Requirements for achieving evidence-based policy in ex ante disaster risk reduction 369 9.9 Summary of MoSSaiC elements contributing to climate proofing 371 9.10 Holistic context of prevention, insurance, and coping strategies of individuals, communities, and governments 372 9.11 Design issues and challenges for linking risk reduction and insurance 373 9.12 Sources of postdisaster financing 376 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x i x Preface ABOUT MOSSAIC To achieve the vision and demonstrate the validity of these premises, three foundations MoSSaiC (Management of Slope Stability in need to be established: the scientific base, the Communities) is an integrated method for community base, and the evidence base for engaging policy makers, project managers, landslide risk reduction in this setting. practitioners, and vulnerable communities in 1. From a scientific standpoint, the root reducing urban landslide risk in developing causes of many landslides in urban com- countries. munities are aggravated by human activi- MoSSaiC was begun with the idea of com- ties that can addressed in relatively simple bining research, policy, and humanitarian and practical ways. A commonly observed interests to address rainfall-triggered land- situation is the negative effect of poor slide hazards through community-based drainage on the stability of slopes com- implementation of surface water manage- prised of weathered materials. This situa- ment measures in vulnerable urban commu- tion can often be remedied through the nities. The vision was to lay sustainable foun- construction of a strategically aligned net- dations for community-based landslide risk work of surface drains. Intercepting and reduction. conveying surface water runoff, household This vision was driven by the following gray water, and roof runoff to ravines and premises: main drains can significantly improve the • Disaster risk mitigation pays, and invest- stability of such slopes. ment in reducing rainfall-triggered land- 2. Community residents have detailed slide hazards in vulnerable communities knowledge of the slopes in their immediate can often be justified. vicinity—where there have been minor landslides, where surface water runs, how • Engaging existing government expertise the topography and vegetation have been for implementing risk reduction measures changed. This information on slope fea- can build capacity, embed good practice, tures is frequently the scale at which land- and change policy. slide-triggering processes operate and the • Ensuring community engagement from scale at which solutions can be found. Vul- start to finish can establish ownership of nerable communities are also where there solutions. is the greatest need for short-term employ- xxi ment (in constructing landslide mitigation ties. It provides guidance on how to imple- measures) and for embedding good slope ment MoSSaiC, evidence of what has worked management practices. Generally, govern- (and of potential risks and challenges), and ments have sufficient technical and mana- guidance on options that should be considered gerial skills that can be harnessed to design to make it work within a specific country. It and deliver appropriate landslide risk may be necessary to adapt the methodology reduction measures in communities. By for environments outside the Eastern Carib- creating a cross-disciplinary management bean—in terms of both general approach and unit from such a skill base, it is possible to specific implementation—to take into account embed MoSSaiC in government practice local landslide risk conditions and institu- and policy. tional contexts. 3. An evidence base for the effectiveness of This is not intended to be a book detailing such targeted landslide risk reduction construction methods. Specific solutions are measures was needed. MoSSaiC was not offered; rather the book presents a sum- started small, with a pilot intervention in mary of our experience, observations, and one community, a catalytic advocate in research. In that regard, two broad issues government, and a small team of in-house deserve emphasis: ensuring the long-term fea- project managers and practitioners. On the sibility of the approach, and being sensitive to evidence of its success, further govern- the scale and extent of the landslide risk prob- ment funding and demand for more inter- lem. ventions followed. This evidence was in • To ensure long-term sustainability of the form of finished construction works, MoSSaiC projects requires the identifica- improved stability of slopes, community tion of localized landslide-triggering pro- endorsement and ownership of the proj- cesses. The structural cause of landslide ect, and demonstration of the combined risk in many vulnerable urban communities skills of the government team. Savings in is the absence of regulation regarding con- terms of avoided losses to the community struction, infrastructure, and land use, and costs to the government were also esti- resulting in increased exposure to land- mated. Decision makers require such evi- slides and increased landslide hazard. dence in order to endorse expenditure on Changes in the natural stability conditions landslide risk reduction and to adopt ex of slopes are mainly a consequence of ante policies. changes in natural slope form, drainage, loading, and surface cover. In urban set- tings, the dominant destabilizing factors CONTEXT FOR MoSSaiC can often be attributed to insufficient drain- age and sanitation infrastructure, cutting The MoSSaiC approach was researched and and filling of slope material, removal of veg- developed in a selection of Eastern Caribbean etation, and high-density construction of small island developing states with the sup- houses. Therefore, from a public policy per- port and funding of governments and interna- spective, landslide risk management is tional development agencies. Implementation strongly linked to the feasibility of address- of the hazard reduction measures was under- ing these unauthorized conditions in a taken by government agencies and community politically, financially, and technically coor- residents in conjunction with contractors dinated manner. If a coordinated strategy is from the community. adopted, the appropriate community-based This book offers a flexible blueprint for landslide mitigation works can be imple- countries that want to use the MoSSaiC mented in accord with other policies to approach to reduce landslide risk in communi- address both the immediate and underlying x x i i   P R E FAC E causes of the landslide risk. However, if an can often be reduced in vulnerable urban ad hoc approach to landslide mitigation is communities in the developing world taken, the root causes of the landslide prob- • To provide practical guidance for those in lem may remain. This can result in ineffi- charge of delivering MoSSaiC on the cient, unsustainable projects that create a ground. false sense of security, provide incentives for new unauthorized occupation, bring In reflecting on and seeking to communi- conflicts into communities and/or with the cate our experience of landslide hazard miti- government, and potentially lose any short- gation, this is neither a conventional policy term landslide risk reduction benefits over book nor an explicit field manual. the medium and long term. The purpose of the book is to take readers into the most vulnerable communities in order • There are large numbers of cities in the to understand and address rainfall-triggered humid tropics with very similar problems, landslide hazards in these areas. Community but that are very different in terms of the residents are not just seen as those at risk, but spatial scale to which MoSSaiC projects as the people with the best practical knowl- have, to date, been implemented. The same edge of the slopes in their neighborhood. As problem (vulnerable communities at risk used here, “community based” means engag- from landslides) in medium or large cities is ing and working with communities to find and likely to require that the approach to land- deliver solutions to landslide risk together. slide mitigation be adjusted to reflect This approach leads governments to develop broader issues. For instance, in larger cities new practices and policies for tackling land- (those whose populations exceed 1 million), slide risk. disaster risk management policies are typi- The book is directed at those responsible cally more complex and demand strategic for initiating, delivering, and sustaining integration and consideration in the con- MoSSaiC in a particular country or city: text of wider development policies. This does not mean that communities do not • Funders and policy makers, typically gov- play a key role in delivering the solution, ernment officials and international devel- but rather that their vision and understand- opment agency staff ing of landslide risk are not unique ele- • MoSSaiC core unit (MCU) personnel ments in the process. (MoSSaiC project managers), typically senior government personnel responsible Success of community-based disaster risk for managing government agencies, depart- management programs is conditioned by local ments, or projects; and leading local experts cultural and social systems. Arguably this is in disaster risk management, landslide haz- best undertaken through careful learning by ard assessment, and community develop- doing, as opposed to a wholesale application of ment best practices from projects that were success- ful in other contexts (Mansuri and Rao 2003). • Government task teams, comprising experts and practitioners responsible for designing and implementing physical ABOUT THIS BOOK works or directly coordinating with com- munities; these are typically engineers, This book has two main aims: community development workers, and technical staff • To demonstrate to international develop- ment agencies, governments, policy mak- • Community task teams with responsibili- ers, project managers, practitioners, and ties at the community level; these are typi- community residents that landslide hazard cally comprised of community residents, CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x x i i i community representatives, and commu- respective benefits of low and high levels of nity-based contractors. process standardization: • Low levels of standardization can promote In addressing these four audiences, the motivation of those charged with delivering book is intended to the project and adaptation to local issues, • assist in securing the political will to under- but can jeopardize the consistency and take community-based landslide risk reduc- quality of risk reduction measures. tion, • High levels of standardization can promote • illustrate how that objective might be real- high levels of quality and speed of delivery, ized by engaging the community, but can suppress innovation and lead to inflexibility in the local context. • provide a scientific grounding in landslide hazard processes and solutions, • demonstrate the steps involved in on-the- ORGANIZATION AND CONTENTS ground delivery, and OF THIS BOOK • emphasize the importance of evaluating The book’s nine chapters provide guidance to project outcomes. project managers and practitioners on the To these ends, the book contains several entire end-to-end process of community- standard sections in each chapter: based landslide risk reduction. While certain chapters are more directly relevant to one • The “Getting started” section is aimed at audience than another, it is helpful for all audi- helping the reader quickly and clearly ences to read the “Getting started” section of understand the chapter’s rationale and how each chapter and be alerted to the nine project to apply MoSSaiC to the local context. milestones. The shared knowledge of mile- • Guiding principles associated with each of stones assists in achieving project ownership the major activities of the program help the and encourages the likelihood of successful policy maker, project manager, or practitio- project continuity, implementation, and post- ner advocate for the methodology with project outcome assessment. stakeholders and demonstrate the central Policy makers and MoSSaiC project manag- role played by community residents. ers should note that chapters 1 (MoSSaiC foundations), 2 (project inception), 4 (com- • The capacity assessment exercise (chap- munity selection), and 9 (project evaluation) ters 2–9) enables the MoSSaiC blueprint to give guidance in areas that predominantly fall be adapted depending on institutional within the remit of policy makers to ensure the structures, protocols, strengths, and weak- existence of a suitable framework. However, it nesses; the nature of the communities; local may fall to project managers to alert the rele- construction practices; and the degree to vant policy maker if local policies are incom- which the local context allows replication plete or require refinement in order to fully of MoSSaiC. allow project implementation. This book standardizes those elements of An overview of the book follows. MoSSaiC that have led to its successful imple- mentation in the Eastern Caribbean, and that Chapter 1. Foundations: Reducing are essential to the overall objectives (such as Landslide Risk in Communities community engagement, mapping localized slope features, and broad drainage design The more socially, economically, and physically principles). In providing a flexible blueprint vulnerable people are, the more disastrous a for MoSSaiC, this book aims to balance the landslide event will be. While there is growing x x i v   P R E FAC E recognition of the increased occurrence of nat- Chapter 2. Project Inception: Teams and ural disasters, there is equal recognition of the Steps lack of on-the-ground implementation of ex ante landslide risk reduction measures. This chapter provides guidelines for the for- This chapter provides an introduction to mation of the MCU which will manage the the MoSSaiC approach, which is focused on project, and of the task teams of practitioners delivering landslide risk reduction measures who will be responsible for project implemen- in vulnerable urban communities in develop- tation. The typical project steps, roles, and ing countries. Specifically, MoSSaiC identifies responsibilities are illustrated. While this pro- and, where appropriate, addresses some of the cess of configuring the teams and project steps physical causes of landslide hazard. may be led by policy makers, established proj- The chapter’s aim is to both inform the ect managers and expert practitioners may reader of the context within which the provide significant assistance. MoSSaiC approach is designed to work and to To achieve the MoSSaiC vision of laying impart something of the vision behind the sustainable foundations for community-based approach. The message is that the rainfall- landslide risk reduction, project managers will triggered landslide hazard faced by the poor- need to est urban communities can often be reduced • build local capacity in the broad area of using relatively simple measures—namely, the landslide hazard reduction while seeking construction of surface drains in appropriate cost-effective solutions; locations. This can be achieved if there is cooperation between government technicians • identify community projects that can be and community residents; hands-on applica- undertaken by existing government-based tion of science and local knowledge; and pro- staff and local communities; and active support from managers, politicians, and • establish team structures to deliver the donor agencies. vision: an MCU that can develop and com- In introducing MoSSaiC, the chapter pro- municate the vision, and task teams to vides the following: develop project strategies and implement • A framework for understanding disaster specific project steps. risk and, more specifically, landslide risk To deliver landslide risk reduction mea- • An overview of trends and lessons learned sures in vulnerable communities requires the in disaster risk management coordination of a diverse team including com- munity residents, field and mapping techni- • Advocacy for taking a proactive approach to cians, landslide experts, engineers, contrac- tackling landslide risk in communities tors, and social development practitioners. • An introduction to MoSSaiC and who This calls for a strong multidisciplinary MCU should be involved to configure and manage specific project steps, roles, and responsibilities. • An overview of how to start a MoSSaiC landslide risk reduction project. Milestone 2: MoSSaiC core unit formed; key responsibilities agreed on and defined This chapter should be read by all stake- holders and should be used by practitioners, project managers, and policy makers alike Chapter 3. Understanding Landslide when explaining the project basis and advo- Hazard cating the MoSSaiC methodology. This chapter provides project managers and Milestone 1: Key catalytic staff briefed on practitioners with an introduction to landslide MoSSaiC methodology processes and illustrates ways of analyzing CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x x v landslide hazard. A core feature of the Chapter 4. Selecting Communities MoSSaiC approach is that it seeks to ensure that all those participating in the program This chapter describes the community selec- have as clear an understanding of the funda- tion process and provides a framework for mental science of landslide processes as pos- identifying areas where slopes are susceptible sible. Shared technical understanding encour- to landslides, the exposure and vulnerability of ages ownership of landslide mitigation communities to these potential landslide solutions by both government and community. events, and hence the overall landslide risk. The first step in the management of land- The aim is to develop a prioritized list of com- slide risk is to define the scope of the project munities for the implementation of landslide and correctly identify the form of the landslide hazard reduction measures using the MoSSaiC risk. The landslide risk reduction and manage- approach. ment process will only be successful if land- Policy makers and project managers need slides are understood in terms of their under- to coordinate on community selection to lying mechanisms and triggers. ensure that there is a transparent process the Understanding landslide processes and MCU can endorse. Failure in this regard can potential triggering mechanisms lead to unintended consequences such as non- selected communities seeking political • ensures that any landslide risk assessment redress, vocal individuals being given a plat- is scientifically informed, form to promote related agendas, and in • ensures that any proposed landslide hazard extreme cases, the demotivation of the MCU management strategies are appropriate to due to the lack of a robust decision-making the specific local landslide hazard, process. This chapter is designed to help the MCU avoid these issues to the extent possible. • determines if a MoSSaiC-style drainage The sophistication of the methods used will intervention will actually address the land- depend on local data and software availability, slide hazard, and the level of expertise of the government • increases the ability of those implementing task team involved. Practitioners with knowl- the project to justify the landslide hazard edge of local landslide issues, of digital map- reduction measures, ping methods, or of assessing community vul- nerability will be able to provide valuable • helps build confidence within the commu- guidance in this task. The outputs could range nity that the fundamental causes of the from a simple prioritized list of communities landslide hazard are being tackled, and to a detailed landslide risk map for a region or • encourages a holistic and strategic approach country. Whatever the method used, commu- to delivering effective landslide hazard nity selection should be justifiable in terms of reduction measures. the science and rationale underpinning the landslide susceptibility assessment and vul- The content of this chapter is designed to nerability of the communities. be accessible to policy makers, project manag- After the communities have been selected, ers, practitioners, community contractors, and the mapping task team seeks to assemble the community members; however, it is likely to most detailed maps available for these com- be project managers and expert practitioners munities. These maps form the basis for the who take the lead in communicating the sci- community-based landslide hazard and ence. drainage mapping exercise described in chapter 5. Milestone 3: Presentation made to MoSSaiC teams on landslide processes and slope stability Milestone 4: Process for community selection software agreed upon and communities selected x x v i   P R E FAC E Chapter 5. Community-Based Mapping the mapping process. This helps create com- for Landslide Hazard Assessment munity ownership and gives recognition to the fact that residents can be involved in the This chapter provides guidance on the com- immediate solutions to landslide risk and lon- munity-based process to map localized slope ger-term improvement in slope management stability features and identify the dominant practices. causes of the landslide hazard in different Milestone 5: Sign-off on prioritized zones and zones of the slope. This is a central chapter for initial drainage plan project managers and practitioners in the fields of mapping, community development, and engineering. The construction of such a Chapter 6. Design and Good Practice for community slope feature map and subsequent Slope Drainage slope process zone map is the basis for assess- ing whether interventions that manage sur- This chapter is concerned with the detailed face water would be likely to reduce the land- design of drains and other surface water man- slide hazard. Quantitative methods are agement strategies in communities where sur- introduced that can be used to investigate the face water has been identified as the main con- physical slope stability processes and confirm tributor to landslide hazard. The aim is to the landslide hazard and effective solutions. design an integrated drainage intervention The final stage described in this chapter is the plan against a fixed budget that has been production of an initial drainage plan and approved by all stakeholders. intervention prioritization matrix for the com- The products of the community-based munity. mapping process detailed in chapter 5 are a Community members need to be fully community slope feature map, a slope process engaged in the mapping process, not just as zone map identifying relative landslide haz- providers of the information, but as active par- ard, and an initial drainage plan. Having iden- ticipants in the development of the maps. The tified surface water management as an appro- motivation for community member engage- priate measure for landslide hazard reduction, ment at this level will vary locally. In some government engineers and technicians should cases, there will already be formal community find the steps outlined in this chapter helpful groups able to mobilize the rest of the commu- in developing the final drain alignments and nity; in others, policy makers and project man- detailed construction specifications. agers may need to take a much more active Project managers and engineers will find role in establishing suitable frameworks and useful resources and methods for estimating approaches to facilitate community engage- surface water and household water discharge ment. into drains, designing the alignment and The contents of this chapter are primarily dimensions of drains, and estimating con- directed to the project manager and those struction costs. team members with engineering or other Milestone 6: Sign-off on final drainage plan technical expertise; however, it is expected that key community members would use this chapter to develop local awareness of urban Chapter 7. Implementing the Planned landslide processes and acquire landslide haz- Works ard mapping skills. The chapter emphasizes that community- This chapter outlines the major issues to be based slope stability mapping is a central ele- addressed when undertaking drain construc- ment of the MoSSaiC program. As such, it is tion. The aim is to provide guidance on the con- important that the project manager, in partic- tracting process (tendering and letting of con- ular, ensures that all residents participate in tracts to community contractors), construction CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x x v i i (implementing the works and good construc- munication and capacity-building methods, in tion practice), and the need to achieve high order to guide the development of locally rel- quality in both (supervision of works is central evant strategies. This chapter gives an indica- to project success). Project managers and prac- tion of some such approaches that have been titioners in charge of construction should use used for MoSSaiC programs. and adapt these resources to local practices and Guidance is provided on who should be told standards and ensure good-quality works. what and when—identifying and understand- The proposed drainage plan agreed upon in ing project audiences, developing appropriate chapter 6 is the document that forms the basis project messages, and using different forms of for all the activities relating to the construc- communication. Formal and informal dialogue tion and delivery of the intervention outlined and community participation are emphasized in this chapter. as the basis for communication throughout the The construction phase of the project is of project. Ways of building local capacity are particular interest to policy makers, project identified for different stakeholder groups, managers, practitioners, community mem- and learning by doing is highlighted as a fun- bers, and the media. It is the point of project damental part of the MoSSaiC capacity-build- delivery as far as construction of landslide ing process. hazard reduction measures is concerned. See- ing that this process is successfully managed Milestone 8: Communication and capacity- within time and budgetary constraints not building strategies agreed upon and only maximizes the likelihood of sound con- implemented struction but also lays the foundation for com- munity ownership postcompletion. A success- Chapter 9. Project Evaluation fully managed project enhances the likelihood of the community becoming a powerful advo- This chapter stresses the importance of evalu- cate for additional interventions and of influ- ating project outputs and outcomes. It pro- encing future policy. Poor construction and vides a rationale for undertaking an evaluation subsequent rejection of the intervention by the and a blueprint for an evaluation strategy. community has the reverse effect—and the Monitoring and evaluation are widely spo- potential of making landslide and flooding ken of in the context of project management, issues worse. This chapter provides guidance yet in many disaster risk reduction initiatives on how to run the implementation process in adequate baseline data are not collected. Con- recognition of these potential challenges. sequently, it can be difficult to find adequate Milestone 7: Sign-off on completed measures of success on which a project may be construction evaluated after just two or three years post- project. This in turn gives rise to the recogni- tion that longer-term project impact evalua- Chapter 8. Encouraging Behavioral tions are rarely, if ever, instigated (Benson and Change Twigg 2004). Landslide risk reduction evi- dence faces the challenge of counterfactual This chapter is concerned with developing analysis—how to demonstrate conclusively communication and capacity-building strate- what would have happened if a different action gies that encourage the adoption of good land- had been taken. slide hazard reduction practices and policies The MCU should therefore understand and by communities and governments. communicate the following: The strategies that work best are likely to be highly dependent on local situations. The aim • The need to secure relevant data both dur- of this chapter is to review behavior change ing and after the project to support project processes and principles, and potential com- impact x x v i i i   P R E FAC E • How the immediate benefits (outputs) and governance of the MoSSaiC project manage- longer-term benefits (outcomes) relate to ment structure. the overall program objectives You may be responsible for working with • That delivering effective landslide hazard MoSSaiC project managers and managing reduction measures provides evidence that their reporting line to the government. This ex ante landslide risk reduction can both book provides guidance on how to undertake work and pay. that process, evidence of what has worked, and information on options to consider. This evidence base is important if the per- Of the entire delivery process, chapters 1 ceptions, practices, and policies of individuals, (MoSSaiC foundations), 2 (project inception), governments, and international funding agen- 4 (community selection), and 9 (project evalu- cies are to be changed regarding community- ation) are perhaps the most significant in pol- based landslide risk reduction. icy terms. They represent areas that demand clear policy frameworks within which the Milestone 9: Evaluation framework agreed upon more technical aspects of mitigation measure and implemented delivery can be undertaken. Lack of clarity in these areas can lead to inefficiency, delay, and failure to align stakeholder expectations. HOW TO USE THIS BOOK Funders and policy makers play a key role in promoting structures that guide the transfer Note to funders and policy makers of project funds to the relevant implementing and community agencies in an efficient and It is important to provide a context when timely manner. Project funds are finite, and advocating for policy change. Globally, the governments can therefore fund only limited amount of aid given to the developing world is construction efforts. Funders and policy mak- increasing and represents only a small fraction ers can seek to ensure that policies are in place of that needed with regard to natural disasters to harmonize disaster risk reduction expendi- (Mills 2004)—the number of which continues ture arising from different sources within a to rise despite efforts to date. Mitigation mea- single community. sures are widely recommended but rarely Funders and policy makers can encourage implemented (Holmes 2008) because the ben- the use of this book within government and by efits are not tangible; they are disasters that other national agencies, nongovernmental did not happen. Not surprisingly, there is clear organizations, and civil society organizations evidence of the continued accumulation of to communicate the vision of community- urban disaster risk (Bull-Kamanga et al. 2003), based landslide risk reduction and to encour- driven largely by the speed of societal change, age feedback so as to further refine the as the vulnerable move to urban areas, the hill- approach and provide additional content. You sides of which are so often already prone to thus have an important role in creating a cul- landslides. Thus, as Yunus (2011) comments, ture of commitment and delivery efficiency, “The more time spent with poor people, the and ultimately in driving changes in ex ante more one realizes that their circumstances are landslide risk mitigation practice and policy. dictated by the systems society has con- structed.” Note to the MoSSaiC core unit As a funder or policy maker, you should anticipate various stakeholder interests aris- The MoSSaiC process begins with a series of ing within community-based interventions. decisions that have to be made almost immedi- Issues that might need to be reconciled include ately to configure the MCU (the project man- political priorities, seeking objectivity in com- agement team). MCU personnel typically com- munity selection, landowner interests, and prise senior government personnel responsible CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x x i x for managing government agencies, depart- If you are a task team leader, you will need ments, or projects; and/or with expertise in a to work closely with the MCU to adapt each particular field such as disaster risk manage- project step according to local capacity, ensure ment, landslide hazard assessment, engineer- that the tasks required to complete each step ing, or community development. are appropriately assigned to a task team, and Your role as a MoSSaiC project manager or identify and build your team. As a practitio- expert advisor means that you should be ner—and since this book is a blueprint—you familiar with the entire contents of this book. will be responsible for capturing and incorpo- You will be responsible for implementing the rating local good practice insofar as it relates policy decisions and for ensuring delivery of to your area of expertise and the MoSSaiC the appropriate measures on the ground in methodology. Under the guidance of the MCU, communities. You will need to apply the you will be responsible for implementing spe- resources in this book according to local fac- cific project steps and tasks, and for ensuring tors. delivery of the appropriate landslide mitiga- Replication should not be considered an tion measures on the ground in communities. automatic process. Sometimes things work for idiosyncratic reasons—a charismatic and liter- Note to community task teams ally irreplaceable leader or a particular and unrepeatable crisis that solidifies support for a Community task teams comprise community politically difficult innovation. One-time suc- residents and those with responsibilities at the cesses thus may not be replicable (World Bank community level, such as community repre- 2004, 108). sentatives and community-based contractors. This book explains the project steps, teams, Community residents are the most critical and supervision levels that are necessary to partners in the program; they are deliver appropriate construction of hazard • participants in the entire process, reduction measures on the ground. It empha- sizes the importance of basing the entire pro- • those to whom the initiative is directed, gram in the community. It provides a logical • those who will “own” the implementation description of how to configure teams and long after construction has finished, design physical measures to reduce landslide hazard in vulnerable communities. The book • an important source of knowledge of local does not tell you exactly what to do, but it slope stability and drainage features in the should improve the likelihood of good project community, and outcomes and of delivering a strategic and • catalytic in making the project happen. holistic community-based landslide risk reduction program. Managing and delivering Each chapter begins with a “Getting community-based projects is hard work, but started” section; these are intended to provide working with the community empowers both an accessible overview to allow communities residents and government teams to contribute to understand key project concepts. If you are their knowledge and skills. a community representative, you may find it helpful to read these in depth. Other particu- Note to government task teams larly relevant book sections to refer to are chapter 5, which describes the community- Government task teams (typically government based mapping process; and chapter 8, which engineers, community development workers, provides guidance on formal and informal and technical staff ) are responsible for spe- community meetings, written and visual cific tasks related to implementing physical resources (e.g., leaflets and posters), and the works on the ground or directly coordinating use of the media. You will need to work with with communities. the government task teams to understand and x x x   P R E FAC E communicate important project messages to process. You may also have the opportunity to community residents and facilitate their par- use your skills in the design and construction ticipation. You should also help the govern- of landslide mitigation measures (see sections ment task teams understand the community 6.4 and 6.5 on drain design, and sections 7.5–7.8 context. on good drain construction practices). If you are a construction contractor or a worker living in a community where MoSSaiC Helpful questions is being implemented, you will have specialist local knowledge that is vital to the success of Table P.1 presents some typical questions the project. You may have useful information about MoSSaiC and where guidance can be to share during the community-based mapping found in this book. TAB L E P.1  Critical questions and decisions addressed in this book CRITICAL QUESTION/DECISION WHERE TO LOOK FOR HELP Why should landslide risk reduction be community based? Chapter 1. Foundations: What are the unique features of the MoSSaiC approach? Reducing Landslide Risk in Where can MoSSaiC be applied? Communities What teams are needed? Chapter 2. Project Inception: What are the project steps? Teams and Steps What are the roles and responsibilities of the teams? What forms of slope failure does the MoSSaiC approach address? Chapter 3. Understanding What is the relevant spatial scale for MoSSaiC interventions? Landslide Hazard How is landslide hazard assessed? How can the most landslide-prone areas be identified? Chapter 4. Selecting How can the most vulnerable communities be identified? Communities How are communities selected for a MoSSaiC intervention? How can landslide hazard be mapped in a community? Chapter 5. Community- How effective will surface water management be in reducing the landslide hazard? Based Mapping for Landslide How is the initial drainage plan developed? Hazard Assessment Where should drains be built to improve slope stability? How can surface water runoff, household gray water discharge, and required drain sizes be Chapter 6. Design and Good estimated? Practice for Slope Drainage What are the most appropriate types of drain design and construction? What construction practices should be promoted? Chapter 7. Implementing the Why is site supervision so important? Planned Works How do communities and governments adopt new landslide mitigation practices and policies? Chapter 8. Encouraging What are the components of a communication strategy? Behavioral Change What are the components of a capacity-building strategy? How can landslide risk reduction measures be evaluated? What are the MoSSaiC key performance indicators? Chapter 9. Project Evaluation What evidence is needed to support ex ante landslide mitigation policies? Where can additional resources be found? At the end of each chapter CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   x x x i REFERENCES Mansuri, G., and V. Rao. 2003. Evaluating Community-Based and Community-Driven Development: A Critical Review of the Evidence. Benson, C., and J. Twigg. 2004. “Measuring Development Research Group. Washington, Mitigation Methodologies for Assessing Natural DC: World Bank. Hazard Risks and the Net Benefits of Mitigation—A Scoping Study.” ProVention Mills, E. 2004. “Insurance in a Climate of Change.” Consortium, Geneva. Science 309 (5737): 1040–44. Bull-Kamanga, L., K. Diagne, A. Lavell, E. Leon, F. —. 2004. Making Services Work for Poor People. Lerise, H. MacGregor, A. Maskrey, M. Meshack, World Development Report. Washington, DC: M. Pelling, H. Reid, D. Satterthwaite, World Bank. J. Songsore, K. Westgate, and A. Yitambe. 2003. Yunus, M. 2011. Blog post August 28. https://plus. “From Everyday Hazards to Disasters: The google.com/114848435876861502546/ Accumulation of Risk in Urban Areas.” posts/9SwwVFedo9P. Environment and Urbanization 15 (1): 193–203. Holmes, J. 2008. “More Help Now Please.” The Economist November 19. x x x i i   P R E FAC E Acknowledgments This book was written while the authors were under the supervision of Patricia Katayama, working in the Latin America and the Carib- Andrés Meneses, and Dina Towbin; and Nita bean Disaster Risk Management team at the Congress undertook copyediting, typesetting, World Bank, Washington, D.C. Colleagues in and proofreading of the manuscript. that team deserve our thanks for supporting This book is based on a community-focused and resourcing our continued commitment to approach and has involved the authors spend- deliver MoSSaiC (Management of Slope Sta- ing many months working in communities bility in Communities) to communities more with residents who are among the most vul- widely in the region and beyond. nerable. We are grateful to members of com- In particular, we thank Francis Ghesquiere munities in Bequia, Dominica, St. Lucia, and and Niels Holm-Nielsen for their continued St. Vincent and the Grenadines with whom we support of initiatives that led to this book. Dis- have spent so much time, and from whom we cussions with other World Bank team mem- have learned so much. We especially acknowl- bers, including Joaquin Toro, Maricarman edge the support and friendship of Robert Esquivel, Tiguist Fisseha, and Rossella Della Charles, McArthur Edwards, and Ruben Leon Monica were enormously helpful throughout. in St. Lucia. Review comments received from colleagues Our vision for MoSSaiC would not have in the Latin America and the Caribbean been realized had it not received support from Region's Disaster Risk Management and Calixte George, Ignatius Jean, and Kenny Urban Unit and Water Supply and Sanitation Anthony as then-members of the government Unit at the World Bank, Washington, D.C., of St. Lucia. Equally accepting of the vision, Kirk Frankson (Office of Disaster Prepared- Donovan Williams, then-Director of the Pov- ness and Emergency Management, Jamaica), erty Reduction Fund in St. Lucia, facilitated us Chamberlain Emmanuel (government of St. in undertaking a pilot program in St. Lucia. Lucia), Abhas K. Jha (East Asia and Pacific This support was continued by his successor, Infrastructure Unit, World Bank) and M. Yaa Joachim Henry. We acknowledge with thanks Pokua Afriyie Oppong (Social Development the technical support for program delivery we Department, World Bank), as part of the World have received from government of St. Lucia Bank review process chaired by Francis Ghes- personnel: David Alphonse, Chamberlain quiere, are acknowledged with grateful thanks. Emmanuel, Peter Gustave, and Cheryl The Office of the Publisher provided edito- Mathurin. Within the Eastern Caribbean sub- rial, design, composition, and printing services region, David Popo of the Organisation of East- xxxiii ern Caribbean States helped facilitate pilot Funding for the work undertaken by the projects in Dominica and St. Vincent and the authors that provided the context for much of Grenadines. this book was provided by the World Bank, the During our time working overseas in com- governments of St. Lucia and Dominica, the munities and in writing this book in Washing- United Nations Development Programme, the ton, D.C., and Bristol, United Kingdom, we U.S. Agency for International Development, received support from many colleagues at the the University of Bristol, SETsquared Partner- University of Bristol, especially Neil Bradshaw ship UK, and the British High Commission, St. and Eric Thomas. Lucia. x x x i v   A C K N O W L E D G M E N T S About the Authors Malcolm Anderson is Visiting Fellow at Elizabeth Holcombe holds a PhD and an Brasenose College and Visiting Professor of MSci from the University of Bristol, where Hydrology at the University of Oxford, a she is a Lecturer in Civil Engineering. She is a Senior Landslide Risk Management Specialist Landslide Risk Management Specialist Con- Consultant in the World Bank’s Latin America sultant in the World Bank’s Latin America and the Caribbean Disaster Risk Management and the Caribbean Disaster Risk Manage- Team in Washington, D.C., and Professor at ment Team in Washington, D.C. Her back- the University of Bristol, United Kingdom, ground is in environmental science and the where he was Pro Vice-Chancellor (Research) numerical modeling of hillslope hydrology from 2005 to 2009. He holds a PhD from the and stability. She has had extensive overseas University of Cambridge, and was elected to a experience in research, project management, Research Fellowship at Sidney Sussex Col- and implementation of landslide risk reduc- lege, Cambridge. He is the author of over 200 tion projects in vulnerable communities in papers, as well as of industry standard soft- the Eastern Caribbean. She has presented ware, and Founder and Editor-in-Chief of the invited papers at international conferences in journal Hydrological Processes. He has worked the Caribbean, Europe, and the Far East, and on many government research projects world- is the author of numerous papers and book wide, principally in the Far East (Hong Kong chapters in the field of landslide risk reduc- SAR, China; Indonesia; and Malaysia), the tion. Her research on MoSSaiC was high- United States, and the Caribbean. He is an lighted in the 2010 World Development Report elected Fellow of the Institution of Civil Engi- and profiled at the Aid Effectiveness Show- neers, London, and was a Council Member of case hosted at the World Bank in 2011. She the U.K. Natural Environment Research received the 2007 Trevithick Award from the Council (2001–07), and a Board Member of Institution of Civil Engineers, London, and the U.K. Engineering and Physical Sciences managed the team that was awarded the Research Council’s Technology Strategy Grand Prize at the 2010 Random Hacks of Board (2009–11). Kindness hackathon in Washington, D.C. xxxv Disclaimer The material in this book is • information of a general nature only that is not intended to address the specific circumstances of any particular project or application; • not necessarily comprehensive, complete, accurate, or up to date; and • not professional or legal advice—if specific advice is needed, a suitably qualified professional should be consulted. It follows that none of the individual contributors, authors, developers, or sponsors of this book, nor anyone else connected to it, can take any responsibility for the results or consequences of any use or adoption of any of the materials or information presented within this book. To the fullest extent permitted by law, the authors accept no responsibility for any loss or damage, which may arise from reliance on the guidance, materials or information contained within this book. Abbreviations cf cubic foot CHASM Combined Hydrology and Slope Stability Model DRM disaster risk management DRR disaster risk reduction ft foot gal gallon GDP gross domestic product GIS geographic information system GPS global positioning system h hour in inch km kilometer kPa kilopascal KPI key performance indicator L liter m meter MCU MoSSaiC core unit min minute mm millimeter MoSSaiC Management of Slope Stability in Communities NGO nongovernmental organization RFT request for tender SAR special administrative region s second SIDS small island developing states UN United Nations All dollar amounts are U.S. dollars unless otherwise indicated. xxxvii “We’re still to some extent sleepwalking our way into disasters for the future which we know are going to happen, and not enough is being done to mitigate the damage.” —John Holmes, UN Under-Secretary-General for Humanitarian Affairs (Lynn 2009) CHAPTER 1 Foundations: Reducing Landslide Risk in Communities 1.1 KEY CHAPTER ELEMENTS 1.1.1 Coverage This chapter outlines the foundations for tion measures in vulnerable communities. The delivery of MoSSaiC (Management of Slope listed groups should read the indicated chap- Stability in Communities) landslide risk reduc- ter sections. AUDIENCE CHAPTER F M G C LEARNING SECTION     MoSSaiC vision and rationale 1.2    Trends in disaster and landslide risk; components of disaster risk management 1.3    MoSSaiC foundations: scientific basis, community base, and evidence base 1.4    MoSSaiC components: book structure and chapter outputs 1.4.5    How to start a MoSSaiC project and who to brief 1.5 F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors 1.1.2 Documents CHAPTER DOCUMENT TO BE PRODUCED SECTION List of senior policy makers who will champion and endorse the project 1.2; 1.5.2 List of staff to be considered for inclusion in the MoSSaiC core unit 1.5.2 1 1.1.3 Steps and outputs STEP OUTPUT 1. Understand the disaster risk context with respect to landslides Relevance of 2. Understand the innovative features and foundations of MoSSaiC MoSSaiC approach to local landslide risk 3. Identify general in-house expertise and the appropriate institutional struc- context identified tures for codifying a local approach toward landslide risk reduction 4. Brief key individuals on MoSSaiC (politicians, relevant ministries, in-house Core unit of team experts) members identified 1.1.4 Community-based aspects ics. Rapid urbanization and the associated growth of unauthorized and densely popu- The chapter introduces MoSSaiC as an inte- lated communities in hazardous locations grated method for engaging policy makers, (such as steep slopes) are powerful drivers in a project managers, practitioners, and vulnera- cycle of disaster risk accumulation. Frequently, ble communities in reducing urban landslide it is the most socioeconomically vulnerable risk in developing countries. Community resi- who inhabit marginal landslide-prone slopes— dents are not just seen as those at risk, but as thus increasing their exposure to landslide the people with the best practical knowledge hazards and often increasing the hazard itself. of the slopes in their area. By engaging and The more socially, economically, and physi- working with communities to find and deliver cally vulnerable people are, the more disas- solutions to landslide risk, governments will trous a landslide event will be. While recogni- develop new practices and policies. tion is growing of the increased occurrence of landslide disasters, there is equal recognition that on-the-ground implementation of land- 1.2 GETTING STARTED slide risk reduction measures is lacking. MoSSaiC aims to address these issues. Its 1.2.1 Briefing note key premises follow. A practical approach to reducing landslide risk • Disaster risk mitigation pays, and invest- ment in reducing rainfall-triggered land- In introducing MoSSaiC, the chapter provides slide hazards in vulnerable communities • a framework for understanding disaster can often be justified. risk, specifically landslide risk; • Engaging existing government expertise • an overview of recent influences on disaster for implementing risk reduction measures risk management (DRM); can build capacity, embed good practice, and change policy. • advocacy for a proactive approach in tack- ling landslide risk in communities; • Ensuring community engagement from start to finish can establish ownership of • an introduction to MoSSaiC’s three founda- solutions. tions; and Specifically, construction of relatively sim- • an overview on starting a MoSSaiC land- ple measures such as surface water drains can slide risk reduction project. often improve slope stability, reduce the land- Many areas of the world are at risk from slide risk to communities, and reduce future landslides and their consequences (figure 1.1). disaster management costs to governments. Rainfall-triggered landslides particularly Landslide mitigation can be achieved through affect developing countries in the humid trop- cooperation between government technicians 2    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S FI G U R E 1.1  Global landslide risk Landslide risk slight moderate severe Source: National Aeronautics and Space Administration (NASA) map adapted from Hong, Adler, and Huffman 2006. Note: NASA scientists assembled the risk map from topographic data, land cover classifications, and soil types. Black dots identify the locations of landslides that occurred from 2003 to 2006. Light blue indicates areas of low risk; purple and dark red indicate areas at the highest risk. and community residents; hands-on applica- —— Scientific methods are used to justify tion of science and local knowledge; and pro- solutions to both communities and gov- active support from managers, politicians, and ernments. donor agencies. • Foundation 2: MoSSaiC is community MoSSaiC vision and foundations based. The MoSSaiC vision is to lay sustainable foun- —— Community residents are engaged in dations for community-based landslide risk identifying landslide risk causes and reduction. These foundations are a scientific solutions. basis for reducing landslide hazard, a commu- —— Contractors and workers from the com- nity-based approach for delivery of mitiga- munity are employed in constructing tion measures on the ground, and an evidence drainage solutions. base demonstrating that such an investment both pays and works (figure 1.2). —— Government managers and practitioners These foundations govern the way in which form teams with the necessary expertise MoSSaiC should be understood, implemented, to work with communities and deliver and integrated into wider policy and practice. mitigation measures. —— The vision is shared and championed in • Foundation 1: MoSSaiC is science based. communities and by governments. —— Localized physical causes (often poor • Foundation 3: MoSSaiC is evidence based. drainage) of landslide hazard are identi- fied. —— Appropriate physical works are deliv- ered to reduce landslide hazard. —— Appropriate mitigation measures that address the causes of landslide hazard —— The majority of project funding and time are identified and implemented. is spent in the communities. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   3 F IG U R E 1 . 2  MoSSaiC premises, vision, and foundations PREMISES • Disaster risk mitigation pays, and investment in reducing rainfall-triggered landslide hazards in vulnerable communities can often be justified • Engaging existing government expertise can build capacity, embed good practice, and change policy • Ensuring community engagement from start to finish can establish ownership of solutions VISION Sustainable foundations for community-based landslide risk reduction FOUNDATIONS Science based Community based Evidence based —— The cost-effectiveness of landslide risk • Landslides are a community issue. Slope reduction is demonstrated. stability in communities is a community- scale issue in that landslides are spatially —— The benefits of community-based land- discrete events caused by localized slope slide risk reduction are demonstrated so stability mechanisms. Each community and that behavior and policy are changed. the corresponding hillside it occupies will Management and community in MoSSaiC have its own unique landslide hazard and vulnerability profile. Thus, determining MoSSaiC recognizes that landslides are both a how to manage slope stability in a particu- management issue and a community issue. lar community requires application of com- munity knowledge of the slope and scien- • Landslides are a management issue. tific/engineering diagnosis of landslide Actions can be taken to reduce or manage mechanisms at the community scale. This landslide hazards or their consequences. community-based approach continues with Slope stability management must involve the construction of drainage by community communities that may inadvertently be members, and with the support of govern- adding to the risk and will almost certainly ment (table 1.1). Ensuring community be affected by it. This management must engagement from start to finish can estab- also involve governments. A government lish ownership of solutions. can choose to take a proactive approach to landslides in communities by identifying Communicating the vision and establishing and enacting appropriate landslide risk MoSSaiC in your country management policies. Governments will often have experts with the combined skills The vision outlined above and detailed in this necessary for reducing landslide risk in chapter may resonate with certain catalytic communities. Engaging existing govern- individuals in a particular country, be they ment expertise for implementing risk community leaders, engineers, civil servants, reduction measures can build capacity, or politicians. These leaders in turn will need embed good practice, and change policy. to communicate the vision to decision makers 4    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S TAB L E 1.1  The key teams and tasks in MoSSaiC TASK Diagnose landslide hazard and Implement physical measures to TEAM design intervention reduce landslide hazard Construct physical measures, Community: residents, Contribute local knowledge of change slope management leaders, and contractors slope, hazard, and vulnerability practices Government: policy makers, Apply in-house scientific, engineer- Issue and supervise contracts, build project managers, and ing, and development expertise in-house capacity practitioners Manage project and teams However, within it, scientific knowledge of and other influential individuals in order to hazards and their effects and technological initiate a MoSSaiC project. alternatives for mitigation take on a com- Government approval is a prerequisite for pletely new meaning, transforming them- initiating MoSSaiC, developing the financial selves into vital instruments at the service of basis for its implementation, and establishing development (Maskrey 1992, 5). a core unit of in-house experts and project managers. Securing government approval Designed as explicitly community based, relies on a clear exposition of MoSSaiC. One of MoSSaiC provides a new method for deliver- the primary functions of this book is to serve as ing landslide risk reduction in the most vul- a resource for this purpose. nerable communities. The combination of fea- Once there is a clear mandate for the estab- tures highlighted below is what makes this lishment of a MoSSaiC project, it is vital to approach unique. engage at-risk communities as early as possi- • It develops sustainable foundations for the ble, set realistic expectations within those delivery of landslide risk reduction mea- communities, and ensure timely project deliv- sures in communities (chapter 1). ery. It is often pragmatic to start small, and then build upon each success as the core unit • It identifies, uses, and builds existing capac- and community adapt the MoSSaiC blueprint ity for risk reduction (chapter 2). to fit the local context. It is easier to embrace a • It identifies the risk drivers so that mitiga- vision if there is evidence of success on the tion measures can be justified (chapter 3). ground. • It provides a method for prioritizing the 1.2.2 What is unique about MoSSaiC? most vulnerable (chapter 4). • Community residents are active partici- Taking an approach focused on community pants throughout the entire process (chap- residents means ter 5). …integrating tasks into a long-term pro- gramme covering all phases of disaster and • It delivers landslide hazard reduction mea- incorporating hazard mitigation into wider sures on the ground (chapter 6). development planning. The methodology of working is necessarily slow, small scale, long • It emphasizes the critical role of site super- term, multidisciplinary, and multisectoral. vision in partnership with community con- Because of its complexity, its incremental tractors (chapter 7). planning, and its dependence on political negotiation, this approach must seem like a • It encourages behavioral change at the recipe for chaos to many experts accustomed community level and within government to working in conventional programs. (chapter 8). CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   5 • It promotes the importance of providing sitating clear communication and a major time evidence of risk reduction achieved (chap- commitment. In the MoSSaiC approach, com- ter 9). munity residents are seen not as passive recip- ients of information, but as agents contribut- 1.2.3 Guiding principles ing both to the landslide hazard and to the solutions. The challenge is to ensure that indi- • Develop a “mitigation mindset” with respect viduals are major participants at every stage in to urban landslide risk. the process so that everyone can own the proj- • Understand that there is no “one size fits ect. Only in this manner can behavioral change all” solution to landslide risk reduction— be achieved. each country and community will have its Similarly, government field teams, techni- own landslide risk profile. cians, and construction supervisors should be treated as contributors and their extensive • Recognize that there is often something field experience seen as a valuable resource. that can be done to reduce the risk—learn These team members are the interface with from other approaches and adapt the the community. If they are not well informed MoSSaiC blueprint. and involved by their managers, their owner- • Learn the value of community knowledge ship of the project cannot be ensured. and the importance of community involve- Sound project management delivers quality ment throughout. interventions. Conversely, poor management can actually make a landslide problem worse, • Realize that the government may already alienate communities and field teams, result in have the skills and know-how to tackle budget overruns, and prevent the MoSSaiC landslide risk in communities. approach from being established in a country. • Look for key individuals in government and The project management and technical teams communities who see the big picture and are responsible for designing and supervising can drive behavioral change. construction, and for achieving a sufficiently high level of engagement with all stakehold- 1.2.4 Risks and challenges ers, so that the intervention meets the required Getting commitment from all key stakeholders goals, complies with necessary standards and safeguards, and encourages replication. Securing a mandate for MoSSaiC from govern- Securing evidence that risk reduction is working ment is necessary for establishing and manag- ing the requisite teams, procuring services and Many disaster risk reduction (DRR) projects resources, and implementing landslide mitiga- lack analysis of medium-term impacts. The tion measures in communities. The multidis- challenge is to keep project engagement by all ciplinary nature of MoSSaiC means that its stakeholders sufficiently strong so that evi- components may fall between or across the dence of postproject performance is kept, ana- purview of different ministries, or that minis- lyzed, and communicated. Only with such evi- tries may not wish to collaborate. A political dence can policy be changed or existing DRR champion may be able to overcome this, but policy measures reinforced. Evidence of risk energetic individuals from different agencies reduction is also important, since evaluations will also need to join forces. of mitigation measures have to respond to the In addition to requiring top-down govern- counterfactual argument of what would have ment action, MoSSaiC is a bottom-up approach happened in the absence of the intervention. to landslide mitigation and needs to have a Psychological and situational barriers secure grounding in communities. This grounding can only be achieved through sub- There are several reasons why relatively few stantial interaction with communities, neces- people, communities, and governments are 6    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S prepared or able to invest in landslide mitiga- their reactions to disasters and may relo- tion measures (Kunreuther, Meyer, and Kerjan cate communities to unsuitable locations. forthcoming): • Lack of risk awareness. Communities may not be aware that they live in a high-land- 1.3 DISASTER RISK: CONTEXT slide-risk area, and governments may not AND CONCEPTS have an adequate basis for identifying the most at-risk communities. 1.3.1 Global disaster risk • Helplessness in the face of landslide risk. This subsection briefly reviews the evidence Communities and governments may be all for the increasing number and consequences too aware of the risk but have little realiza- of disasters caused by natural hazards. It pro- tion of the potential for relatively low-cost, vides both the broad context for DRM and the in-house solutions. specific context for the management of slope stability in communities. • “Samaritan’s dilemma.” Communities may avoid investing in good slope manage- Increases in the number of disasters ment practices and risk reduction measures Reports from international development agen- on the assumption that a government (the cies and from the geoscience and engineering “good Samaritan”) will assist them in case communities point to an increase in the occur- of disaster. rence of natural hazards and their conse- • Procrastination. There is a natural ten- quences (figure 1.3), especially with respect to dency to postpone taking actions that countries with low to medium levels of devel- require investments of time and money. opment (AGS 2000; Alcántara-Ayala 2002; UNDP 2004, 2008). See IFRC (2004) for a • Budget constraints. Communities may not comprehensive discussion of this trend. be able to afford to invest in landslide risk This apparent increase has many possible reduction measures. Governments may not explanations (IEG 2006; IFRC 2004), includ- have sufficient understanding of the poten- ing the following: tial solutions and associated benefit-cost ratios, and therefore are unable to justify • Increase in the reporting and recording of the expenditure. disasters. Improved communication and the development of international and local • Short-term planning horizons and hyper- disaster databases have enabled the system- bolic discounting. People in the most vul- atic recording of disasters. nerable communities may be living hand to • Development activities. Construction, mouth and consequently be unwilling to mining, and agriculture affect the natural consider putting money toward low-cost environment and can increase some hydro- slope management solutions that will not meterological hazards (such as landslides, provide for their daily needs. Governments erosion, flooding, and drought). might place more value on projects that show immediate benefits rather than on • Global anthropogenic effects such as cli- investing to offset a future loss that may or mate change. For example, a rise in tropical may not occur. sea temperatures of approximately 1 degree Celsius over the past century may have con- • Learning from failures. People often do tributed to an increase in weather-related not seem to learn from past experiences of disasters. disaster. Following a landslide, people may rebuild their homes in the same or similar • Socioeconomic and environmental driv- location. Governments also tend to repeat ers leading to increased exposure and CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   7 vulnerability. Poverty, drought, and famine catastrophic way, especially in small island can result in people moving to deltas, flood- developing states (SIDS) (World Bank 2010b). plains, the steep slopes on the fringes of For example, Granada lost 200 percent of its urban areas, and other marginal areas GDP to Hurricane Ivan (World Bank 2005a). exposed to natural hazards. Observed trends in disaster risk are not simply a physical phenomenon, but are closely Such evidence further supports arguments related to the process of human development: for DRR that have been advanced in the inter- “the development choices of individuals, com- national development policy community in munities and nations can generate new disas- recent years (DFID 2004; Pelling and Uitto ter risk” (UNDP 2004, 1). Analysis of time- 2001; Twigg 2004). series data has provided insight into the causative factors of the increased losses asso- Increases in the cost of disasters ciated with disasters. A study of mainland U.S. Paralleling the increase in the number of disas- hurricane damage from 1900 to 2005 shows ters has been the rise in their consequences that if damage data are normalized (with 2005 with regard to direct and indirect impacts, and as the datum) with respect to changes in infla- insured and uninsured losses (figure 1.3). It is tion and wealth at the national level, and widely recognized that the incidence and changes in population and housing units at the impact of disasters caused by natural hazards coastal county level, there is no trend in dam- disproportionately affects developing coun- age over time (figure 1.4) (Crompton et al. tries. Numerous studies have documented evi- 2010; Crompton and McAneney 2008; Pielke dence of the human, economic, and environ- et al. 2008). The absence of a trend in normal- mental losses experienced by developing ized loss data suggests that increased observed countries at the local and national levels (e.g., losses are attributable to increases in the num- Charveriat 2000; Rasmussen 2004; UNDP ber of buildings over time; thus, it matters 2004). Such losses can affect the gross domes- greatly what is built, where it is built, and how tic product (GDP) of developing countries in a it is built. FI G U R E 1. 3  Number of great natural catastrophes and associated economic losses worldwide, 1950–2010 a. Number of events with trend b. Overall and insured losses with trend number $, billions 16 250 2 14 200 12 10 150 8 6 100 4 50 2 0 0 1950 1960 1970 1980 1990 2000 2010 1950 1960 1970 1980 1990 2000 2010 climatological events (extreme drought/temperature, forest fires) overall losses (2010 values) hydrological events (floods, mass movements) insured losses (2010 values) meteorological events (storm) trend in overall losses geophysical events (earthquake, tsunami, volcanic eruption) trend in insured losses Source: © Münchener Rückversicherungs-Gesellschaft, Geo Risks Research, NatCatSERVICE 2011. 8    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S spatial and temporal scales, affected parties, FI G U R E 1.4  Normalized losses from U.S. and methods of risk assessment and risk man- Gulf and Atlantic hurricane damage, agement. 1900–2005 Studies by regional networks such as La Red $, billions (Latin America) and Periperi (southern Africa) 160 provide evidence that smaller-scale and 140 “everyday” disasters (categories 0–2) have 120 been increasing in developing countries in 100 recent years (Bull-Kamanga et al. 2003). The 80 landslide risk reduction approach described in 60 this book has been built on experiences gener- 40 ally relating to categories 0–2. MoSSaiC may 20 also be applicable to the higher categories of 0 landslide catastrophe. 1905 1925 1945 1965 1985 2005 Source: Pielke et al. 2008. Global landslide risk Note: Data are normalized to 2005 by adjusting for Rainfall-triggered landslides represent a sig- changes in inflation, wealth, and housing units. The black line is an 11-year centered moving average. nificant but underreported threat to lives, property, and development, particularly in Southeast Asia and Latin America and the Recording disasters Caribbean (UNU 2006). Available data indi- To assist in the analysis and management of cate that the majority of fatalities occur in risk, disasters are recorded and categorized by lower-middle- and low-income countries (fig- various agencies. For example, the Emergency ures 1.5 and 1.6), and that in excess of 2 million Events Database (EM-DAT) is maintained by people are exposed to landslide hazards the World Health Organization Collaborating worldwide (UNISDR 2009). However, the full Centre for Research on the Epidemiology of impact of landslides is masked by broader sta- Disasters (CRED). In EM-DAT a disaster is tistics relating to the precipitation events that defined as an event in which 10 or more people trigger them and the concurrent wind damage, are killed, 100 or more are injured, or where floods, and storm surges. For a particular rain- damage is sufficient to call in international fall-triggered disaster, it is possible that “losses agencies (UNDP 2004). Munich Re classifies from landslides may exceed losses from the disaster risk in terms of categories of catastro- overall disaster” (USGS 2003, 7). phe (table 1.2). The catastrophes in each cate- In the humid tropics, high-intensity and gory are likely to have different return periods, high-duration rainfall events act as the main TAB L E 1.2  Categories of catastrophe CATEGORY DEFINITION 0 Extreme natural event No fatalities, no property damage 1 Small-scale loss event > 1 fatality and/or small-scale damage 2 Moderate loss event > 10 fatalities and/or damage to buildings and property 3 Severe catastrophe > 20 fatalities, overall losses > $50 million 4 Major catastrophe > 100 fatalities, overall losses > $200m 5 Devastating catastrophe > 500 fatalities, overall losses > $500 million 6 Great natural catastrophe Thousands of fatalities, economy severely affected, extreme insured losses Source: © Münchener Rückversicherungs-Gesellschaft, Geo Risks Research, NatCatSERVICE 2011. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   9 impact of rainfall-triggered landslides in areas F IG U R E 1 . 5  Exposure and fatalities of unauthorized housing is well recognized: associated with rainfall-triggered landslides, by income class Poverty can compel people to migrate to larger cities in search of employment oppor- a. Exposure tunities. Without the economic means to par- number of people per year ticipate and integrate into town and city soci- 1,000,000 no data, 1.3% eties, the poor create shantytowns often on low-income country, 19.5% the outskirts of cities in areas with high haz- 100,000 ard exposure risks. For instance, in the case of 10,000 the major rain-induced landslide in Venezu- 1,000 lower-middle-income country, 62.9% ela in 1999, which affected between 80–100 100 thousand people, most of the thirty thousand disaster deaths can be traced back to an infor- 10 upper-middle-income country, 8.4% mal settlement that was washed away during high-income country, 7.9% 0 the event (OAS 2004, 2). As well as causing major landslide disas- b. Modeled fatalities ters, a single rainfall event can trigger numer- average number of people per year (%) ous small- to medium-size landslides (AGS 100 2000)—a scale not recognized in most inter- low-income country, 41.4% 80 national records of disasters. The frequent occurrence of highly localized disasters 60 anticipates the potential for much larger 40 lower-middle-income country, 40.5% disasters. 20 To address landslide-related losses, and the upper-middle-income country, 10.8% high-income country, 7.8% interaction of development activities with 0 slope stability, this accumulation of risk must low income = per capita GNI < $935 be tackled. The ability to mitigate small events lower middle income = per capita GNI $936–$3,705 effectively, or to limit their impact, could result upper middle income = per capita GNI $3,706–$11,455 high income = per capita GNI > $11,456 in an increased capacity to manage the risks Source: UNISDR 2009. associated with larger events (Bull-Kamanga et al. 2003). Note: GNI = gross national income. Landslide risk and MoSSaiC With respect to rainfall-triggered landslide trigger for landslides by reducing the shear risk, the Caribbean (where MoSSaiC has been strength of the slope materials. Some climate developed) is typical of many developing change predictions suggest an increase in the regions in the humid tropics. The steep slopes number and intensity of extreme rainfall and deep soils that characterize much of this events in these regions. However, even with- region are naturally prone to landslides, which out climate change, the susceptibility of slopes are triggered by high-intensity or high-dura- to landslides is being increased by develop- tion rainfall (Lumb 1975). ment activities involving earthworks (cuts and A combination of poverty and increasing fills) and construction—whether planned or levels of urbanization is resulting in the con- unauthorized. These activities change slope struction of unauthorized settlements on such geometry, strength, loading, vegetation cover, slopes, as they are often the only available and surface water and groundwater regimes. location for the poor (Board on Natural Disas- Thus, the process of development can increase ters 1999). Like many other developing coun- the physical landslide hazard while exposing tries, urban areas in Latin America and the more of the most vulnerable people and struc- Caribbean suffer from low-quality housing, tures to these hazards. The occurrence and inadequate (or unenforced) urban planning 1 0    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S FI G U R E 1.6  Global rainfall-triggered landslide fatalities modeled fatalities per million per year (relative) risk class 100 10 Dominica 9 Comoros 8 7 São Tomé and Principe St. Lucia 6 Solomon Islands 10 Vanuatu 5 San Marino Liechtenstein Timor-Leste Cape Verde 4 Fiji Mauritius Monaco New Caledonia Papua New Guinea 3 Montenegro Belize Bhutan Sierra Leone Guatemala Brunei Darussalam Equatorial Guinea 2 Costa Rica Haiti Jamaica Albania El Salvador 1 Trinidad and Tobago Nicaragua Nepal Iceland Panama Lao PDR Lebanon GeorgiaHonduras 1 Liberia Ecuador Malta Guyana Slovenia Guinea Cameroon Ethiopia Malawi Madagascar Myanmar Cyprus Lesotho Armenia Croatia Benin Kenya Philippines Macedonia, FYR Eritrea Bolivia Korea, Dem. People’s Rep. Colombia Gambia Malaysia Namibia Togo Tanzania Indonesia Kyrgyzstan Austria Yemen, Rep. Swaziland Ireland Norway Serbia Côte d’Ivoire Mexico Vietnam Uruguay Korea, Rep. Nigeria Israel Tunisia Afghanistan Italy Turkey Pakistan Oman Bulgaria Iraq Japan 0.1 Czech Republic Niger Argentina Thailand Bangladesh India Moldova Zimbabwe Australia Spain Mali Brazil Slovak Republic Canada Sudan Iran, Islamic Rep. China South Africa France Burkina Faso Hungary United Kingdom Germany Russian Federation Kazakhstan Ukraine Uzbekistan Poland United States 1 10 100 modeled fatalities per year (absolute) Source: UNISDR 2009. Note: Approximately 2.2 million people are exposed to landslides worldwide, but many small landslide events causing deaths are not internationally reported. controls, and insufficient investment in infra- MoSSaiC is specifically targeted to reduce structure (Charveriat 2000). the frequent small- to medium-size rainfall- The resulting landslide risk is the product of complex interactions between the inherent triggered landslides that occur in weath- susceptibility of slopes to landslides (related to ered soils and that are exacerbated by their soils and geology, topography, hydrology, human influences on slope drainage and and vegetation), the influence of human activi- geometry. It is designed for application in ties in affecting these factors at a highly local- the most economically, socially, and physi- ized scale, and the vulnerability of communi- cally vulnerable communities. ties to the impact of landslides. 1.3.2 Disaster risk management structure, or the environment) to that hazard, and the vulnerability of those elements to Defining risk damage by the hazard. Risk is commonly DRM requires an understanding of what is expressed as a function of hazard, exposure, driving the risk. This can be broken down into and vulnerability. three components: the physical hazard, the A natural hazard (such as a landslide, flood, exposure of different elements (such as peo- storm, volcanic eruption, or earthquake) is ple, buildings, public utilities, economic infra- defined in terms of its frequency (annual prob- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 1 ability or return period), magnitude, and type communities will find economic recovery at a particular location or within a wider harder than richer communities. region. Where the likelihood of a particular • The temporal exposure of different groups. hazard is expressed in relative or qualitative Differing degrees of exposure are associated terms rather than as a probability, it is more with being at home (greater probability at appropriate to refer to an area’s susceptibility night than during the day) versus being in a to the hazard. school or workplace (greater probability The exposure of people, structures, ser- during the day than at night). vices, or the environment to a specific hazard is determined by the spatial and temporal • The temporal vulnerability of a group in location of those elements with respect to that a specific location exposed to the land- hazard. Vulnerability is an expression of the slide hazard. Differing degrees of physical potential of the exposed elements to suffer vulnerability (injury or loss of life) will per- harm or loss. Thus, exposure and vulnerability tain depending on whether someone is out- relate to the consequences or the results of a doors, in a wooden house, or in a concrete natural force, and not to the natural process structure when a landslide occurs. itself (Crozier and Glade 2005). In many cases, • Variation of vulnerability for different exposure is treated as an implicit part of vul- nerability assessment, as described below. elements. A house may have the same vul- Vulnerability is related to the capacity to nerability to a slow or rapid landslide event, anticipate a hazard, cope with it, resist it, and but people living in the house will have a recover from its impact. It is determined by a lower vulnerability to the slower event than mix of physical, environmental, social, eco- to the rapid event, depending on their abil- nomic, political, cultural, and institutional fac- ity to leave the house. tors (Benson and Twigg 2007). Vulnerability These and other factors need to be consid- may be expressed qualitatively or quantita- ered to assess vulnerability to landslides. tively, in terms of direct or indirect damage Because of the wide range of factors involved, and tangible or intangible damage. The dam- it has been noted that “vulnerability assess- age can be physical, environmental, social, or ment is a complex issue, which is regularly not economic and have an impact at a range of considered in an appropriate and thoughtful local and national scales. The degree of direct manner” (Crozier and Glade 2005, 27). physical or economic damage is often expressed in cost terms or on a scale of 0–1 The disaster risk management process (from no damage to total loss). Indirect and A typical DRM process will include the follow- intangible damage is usually more difficult to ing steps. quantify. The opposite of vulnerability is resil- ience (of people) or reliability (of structures). Step 1: Disaster risk assessment Vulnerability assessment is especially com- plex for landslides since a wide range of effects • Analyze the risk. Identify and measure the have to be considered, such as the following: frequency, magnitude, and type of hazard; and the vulnerability and exposure of the • The location, type, magnitude, and veloc- elements at risk. ity of the landslide hazard­ . These will directly determine its spatial impact and • Understand the risk. Identify the underly- the exposure of elements at risk. ing hazard and vulnerability processes, causes, and effects. • The physical and socioeconomic vulner- ability of groups. Children and the elderly • Evaluate the risk. Compare with other risks or disabled will be able to respond less and decide whether to accept or treat the quickly than others; poorer households and risk. 1 2    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S Step 2: Disaster risk reduction impact of potential natural hazard events” (Benson and Twigg 2007, 16). Table 1.3 defines • Identify DRR options. some of the terms commonly used to describe —— Avoid the hazard. Reduce exposure by DRM components and gives examples of the enforcing planning controls, emergency activities typically involved. evacuation, or permanent relocation. The ultimate goal of DRM is to reduce disas- ter risk to an acceptable level. Figure 1.7 illus- —— Reduce the hazard, usually through trates how this can be achieved via different some form of engineering measures. DRR options (corresponding to those listed in —— Reduce the vulnerability and/or expo- Step 2 above): reducing the consequences, sure. Increase the reliability of struc- directly reducing the hazard, or redesigning to tures using engineering and building reduce both hazard and consequences. controls; or the resilience of people The concept of acceptable risk through public awareness, early warn- ing, and planning for disaster response Elimination of risk is rarely feasible; however, and recovery. mitigation measures can reduce risk. Risk reduction is thus undertaken in the context of —— Transfer the risk, using disaster funds seeking to achieve what society and the com- and insurance. munity regard as “acceptable risk” (or “tolera- • Plan the risk treatment. Design the selected ble risk”). According to the International risk treatment option. Union of Geological Sciences Working Group on Landslides, acceptable risk can be defined • Implement the risk treatment. as “a risk that society is willing to live with…in • Monitor the risk. the confidence that it is being properly con- trolled, kept under review, and further reduced Taken together, DRR measures are often as and when possible” (Dai, Lee, and Ngai referred to as mitigation. Mitigation encom- 2002, 78). When considering acceptable risk passes any structural (engineering) or non- criteria for landslides, the following general structural (planning, policy, public awareness) principles, defined by the International Union measures “undertaken to minimise the adverse of Geological Sciences, could be applied: TAB L E 1. 3  Disaster risk management components COMPONENT EXAMPLE ACTIVITY Risk Risk identification, • Hazard mapping, prediction and monitoring assessment analysis and evaluation • Community vulnerability assessment • Social risk perception analysis • Risk mapping Ex ante risk Risk prevention and • Planning controls reduction mitigation • Building codes • Structural hazard reduction measures • Risk financing: risk transfer (insurance), risk retention (funds) Disaster preparedness • Public awareness • Early warning • Institutional strengthening Ex post Disaster response • Emergency management disaster • Humanitarian relief management Disaster recovery • Postdisaster needs assessment • Reconstruction and rehabilitation CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 3 • Tolerable risks may vary from country to F IG U R E 1 .7  Disaster risk management country and within countries, depending options on historic exposure to landslide hazard, and the system of ownership and control of large reduce redesign slopes and natural landslide hazards (Dai, (loss of life, cost, indirect impact) consequences Lee, and Ngai 2002, 78). ar t Defining acceptable risk is complex, and er’s consequences ne only in the most data-rich circumstances can it gi en be seriously attempted in a quantitative man- ner. Figure 1.8 illustrates the definitions devel- oped in Hong Kong SAR, China. Figure 1.8a illustrates a preferred definition, in that there accept reduce hazard is no acceptable risk zone defined; figure 1.8b small illustrates an alternative definition where it is low hazard high (probability of failure) considered reasonable for society to accept a certain level of risk. Source: International Center for Geohazards, Norway. Such numerical formulations, and associ- ated representations, of risk are only a guide to what a given society might accept. More com- monly, social and political judgments are made • The incremental risk from a hazard to an individual should not be significant com- on a case-by-case basis to help determine pared to other risks to which a person is acceptable risk (Bunce, Cruden, and Morgen- exposed in everyday life; stern 1995; Dai, Lee, and Ngai 2002) and guide measures that are actually implemented. • The incremental risk from a hazard should, wherever reasonably practicable, be 1.3.3 Recent influences on disaster risk reduced i.e., the As Low As Reasonably Practicable (ALARP) principle should management policy and implications for apply; MoSSaiC • If the possible loss of life from a landslide Shift from ex post to ex ante policies incident is high, the risk that the incident might actually occur should be low. This The increase in disaster risk described above accounts for the particular intolerance of a has been recognized and responded to by pol- society to incidents that cause many simul- icy makers, governments, and development taneous casualties; agencies. DRM and DRR are now an estab- • Persons in the society will tolerate higher lished part of the extensive development liter- risks than they regard as acceptable when ature, and are increasingly being main- they are unable to control or reduce the risk because of financial or other limitations; streamed in policy—often in conjunction with climate change adaptation and poverty reduc- • Higher risks are likely to be tolerated for tion programs. This recognition has been the existing slopes than for planned projects, product of, and has contributed to, the com- and for workers in industries with hazard- ous slopes, e.g., mines, than for society as a plexity of the DRR advocacy and disaster whole; response landscapes (figures 1.9 and 1.10). Notwithstanding, experts maintain that there • Tolerable risks are higher for naturally occurring landslides than those from engi- is still insufficient global focus on and commit- neered slopes; ment to DRR (Sweikar et al. 2006). As a long- term, low-visibility process that offers no • Once a natural slope has been placed under monitoring or risk mitigation measures guarantee of tangible rewards, disaster mitiga- have been executed, the tolerable risks tion is often overlooked by both sustainable approach those of engineered slopes; development projects and the more immedi- 1 4    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S FI G U R E 1.8  Societal landslide risk in Hong Kong SAR, China a. Preferred definition b. Alternative definition frequency per year frequency per year 1.E+00 1.E+00 1.E−02 unacceptable 1.E−02 unacceptable intense intense 1.E−04 scrutiny 1.E−04 scrutiny region region ALARP 1.E−06 ALARP 1.E−06 broadly acceptable 1.E−08 1.E−08 1 10 100 1,000 10,000 1 10 100 1,000 10,000 n or more fatalities n or more fatalities Source: Dai, Lee, and Ngai 2002. Note: ALARP = as low as reasonably practicable. ate concerns of humanitarian aid responses to after the event (Mechler, Linnerooth-Bayer, disasters. Even though it is acknowledged that and Peppiatt 2006). ex ante risk reduction is likely to be preferable The emergence of new policy and funding from both humanitarian and economic per- trends generally occurs over a decadal cycle, spectives (Blaikie et al. 1994), 90 percent of which makes recording and reporting on proj- bilateral and multilateral disaster-related ect impact very important, given the lagged funding is still spent on relief and recovery response between funding and project feed- FI G U R E 1.9  International advocacy landscape for disaster risk reduction COALITION NONGOVERNMENTAL BILATERAL MULTILATERAL ORGANIZATION BOND Group (UK) AusAID (Australia) ECHO IWG/ECB Project Action Aid (UK) BMZ (Germany) DIPECHO GDIN Christian Aid (UK) CIDA (Canada) IASC Steering Committee IAWG (Nairobi) Catholic Relief Services DFID (UK) UNDP ICVA IFRC DMFA (Denmark) UN ISDR InterAction Lutheran World Relief FFO (Germany) UN OCHA ProVention Consortium Mercy Corps (UK/USA) GMZ (Germany) UN Special Envoy Sphere Project Oxfam (UK/USA) MOFA (Japan) VOICE PHREE-WAY NMFA (Norway) Plan International (UK) SIDA (Sweden) INTERNATIONAL FINANCE Practical Action (UK) SDC (Switzerland) RESEARCH Red Cross (UK/USA) USAID (USA) African Development Bank ADPC (Thailand) RiskRED US State Department Asian Development Bank ADRC (Japan) Save the Children (UK/USA) Caribbean Development Bank BHRC (UK) Tearfund (UK) Inter-American Development Bank CRED (Belgium) World Vision (UK/USA) International Monetary Fund ODI (UK) The World Bank Source: Sweikar et al. 2006. Note: Organizations listed in italics play an identifiable role in advocacy; those listed in boldface are involved in coordination. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 5 F IG U R E 1 .1 0  UN disaster response organizational framework UN General Assembly Coordination of humanitarian, policy development, and Disaster Reduction Programme humanitarian advocacy ISDR UNESD Economic OCHA International Strategy for Central Office for the and Social Disaster Reduction Development Register Coordination of Humanitarian Affairs IATF UN/ISDR UNDESA Inter-Agency Task Force Inter-Agency Secretariat Emergency Economic ERC for Disaster Reduction of the ISDR Telecommunications and Social Emergency and Relief Affairs WGET, IASC-RGT, Coordinator and CDC DESC WCDR IDD Support and CMCS IASC World Conference on Inter-Agency Internal Coordination Civil Military Inter-Agency Standing Disaster Reduction Displacement Division to ECOSDC Coordination Committee Section Early Recovery Cluster UNDAW UN Agencies Advancement of Women Crisis prevention and recovery Disaster management programme UNDP Drylands Development Centre Lead Agency RELIEFWEB UNCRD Shelter and sustainable human settlements Regional UN-Habitat Disaster management programme Development HIC Health Action in Crisis, Division of Humanitarianinfo.org WHO Emergency and Humanitarian Action Farming, livestock, fisheries, and forestry, GLIDEnumber Global Information and Early Warning FAO System, GeoWeb UNDMTP Hunger as a result of natural disasters and World Food Training Virtual OSOCC food security in developing countries Programme Programme Environmental issues in disaster management, Information system DEWA (early warning and assessment), UNEP GRID (information database), APELL ProVention (emergencies at the local level) Consortium Rapid assessment and Health, education, equality, and UNICEF protection of children in disasters international coordination on-site Prevention strategy, global early warning UNESCO IRIN UNDAC system, and impact assessments News United Nations UNHC Assessment and Human rights of displaced people Service Human Rights Coordination Team Search and rescue UN Regional Agencies INSARAG International Search and UNECA CEPAL UNECE UNESCAP UNESCWA Rescue Advisory Group Africa Latin America Europe Asia and the Western and the Caribbean Pacific Asia Source: Lloyd-Jones 2006. back. If something works, evidence needs to be ever, on-the-ground delivery has not material- given, since this is the driver for further policy ized in a correspondingly significant way. change and funding. The shift of emphasis Wamsler (2006, 159) notes: from an ex post (response and recovery) to an During the past three decades policy state- ex ante (mitigation and preparedness) ments by all major agencies have included approach to disasters has been reflected in the risk reduction as a pre-condition and an portfolio of projects funded by development integrated aspect of sustainable develop- banks for a number of years (IDB 2005). How- ment… but when it comes to practical imple- 1 6    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S mentation, comparatively little has been hazard, and the community basis for delivery done. on the ground. The following discussion A recent World Bank project evaluation explores recent influences on ex ante DRM study provides clear evidence that disaster policy in relation to these three areas, with preparedness and mitigation need to be particular reference to landslide risk and the addressed as a priority (table 1.4). importance of the government-community Despite the seeming shift to ex ante DRM relationship. This discussion provides the pol- policy, there is an apparent lag in funding and icy context for MoSSaiC. consequently in the delivery of that policy on Need for evidence that mitigation pays the ground. With respect to landslide risk reduction, the following appear to be the key Studies undertaken with respect to specific issues: DRM projects have consistently indicated that mitigation pays (World Bank 2010b): in gen- • Decision makers will not naturally choose eral, for every dollar invested, between two to invest in a project with unseen benefits and four dollars are returned in terms of (the main benefits of DRR are in the future avoided or reduced disaster impacts (Mechler in terms of losses avoided). 2005; Moench, Mechler, and Stapleton 2007). • A top-down policy approach to DRR can, in On the other hand, some cases, actually make it difficult to Building a culture of prevention is not easy, identify local physical risk drivers and however. While the costs of prevention have thereby find a practical solution to the haz- to be paid in the present, its benefits lie in the ard. distant future. Moreover, the benefits are not tangible; they are the wars and disasters that • The top-down approach often fails to do not happen. So we should not be surprised engage with the most vulnerable, who will that preventive policies receive support that therefore not be motivated to adopt new is more often rhetorical than substantive (Annan 1999). practices or own the mitigation measures. Thus, practical implementation of landslide Evidence suggests that an individual’s deci- mitigation measures in vulnerable communi- sion-making process will be biased against the ties is rare, and so is evidence of the effective- activities and costs involved in reducing the ness of mitigation. risk of low-probability, high-consequence Three interrelated areas need strengthen- events. Meyer (2005) argues that our ability to ing—the evidence base for investment in risk make optimal mitigation decisions is hindered reduction, the scientific basis for reducing the by three deep-rooted biases: TAB L E 1.4  Lessons learned from World Bank natural disaster projects MENTIONS IN IEG RANK LESSON LEARNED DATABASE 1 Disaster management, preparedness, and mitigation need to be addressed 49 2 Simple and flexible procurement is fundamental to expeditious implementation 40 3 Lessons regarding project coordination units and/or working with existing agencies (pros and cons) 31 4 Maintenance is critical for sustainability 25 5 Simple project design is more important when activities to be implemented are urgent 25 6 Community participation produces several identifiable benefits 25 Source: IEG 2006. Note: Lessons are from 303 completed World Bank natural disaster projects as identified by the World Bank’s Independent Evaluation Group (IEG). CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 7 • How we learn from the past—We tend to investments to be compared. For example, learn by focusing on short-term feedback. modeling the costs and benefits of preventing hurricane damage to properties (by protecting • How we see the future—We tend to see the windows and doors and upgrading roofs) in future as a simple extension of the present two villages in St. Lucia demonstrated attrac- rather than anticipating low-probability tive benefit-cost ratios for a wide range of events such as disasters. potential discount rates (Hochrainer-Stigler et • How we make the trade-off between imme- al. 2010) (figure 1.11). diate capital investment in risk reduction Cost-benefit analysis uses a discount rate to compared with future savings in avoided compare economic effects occurring at differ- losses—We tend to overly discount the ent times. Discounting converts future eco- value of ambiguous future rewards com- nomic impacts to their present-day value. The pared to short-term costs. discount rate is usually positive because resources invested today can, on average, be Taken together, Meyer argues, these limita- transformed into more resources later. If hur- tions seem to explain many of the biases that ricane mitigation is viewed as an investment, have been observed in real-world DRM deci- the return on that investment can be used to sions—and, most critically, why we seem to decide how much should be spent on mitiga- have such difficulty correcting them. To over- tion. Assuming a 25-year project lifetime and a come these biases, it is even more urgent that 12 percent discount rate, the example in fig- physical evidence be provided for the effective- ure  1.11 shows such an intervention yields a ness of DRR—not just on the basis of economic benefit-cost ratio of 1.5:1—in other words, it investment, but also in terms of the social and pays; but with an assumed project lifetime of indirect benefits to those most at risk. only five years, cost exceeds benefit (benefit- An example showing that mitigation pays is cost ratio of 0.75:1). provided by a series of studies conducted by The application of catastrophe modeling to the Wharton School of the University of Penn- wooden homes in Canaries, St. Lucia, illus- sylvania. These studies used catastrophe risk trates how the effect of climate change on the models to enable cost-benefit assessments to benefits of hurricane mitigation measures can be made of mitigation measures. The four be assessed (Ou-Yang 2010). Figure 1.12 shows basic components of a catastrophe model— the change in benefit-cost ratios for different hazard, inventory, vulnerability, and loss— mitigation measures over different time scales enable risk to be quantified in terms of cost (Wharton School 2008). In the case of a hur- ricane, the four components can be defined as F IGUR E 1.11  Benefit-cost ratio for hurricane-proofing prevention measures for follows: houses in Canaries and Patience, St. Lucia • Hazard, quantified by the frequency, mag- benefit-cost ratio nitude, and path of the hurricane 5 • Inventory, the list (or portfolio) of proper- 4 ties exposed to the predicted hurricane 3 25 years • Vulnerability, the susceptibility to damage 2 10 years of the exposed structures 5 years 1 • Loss, the resulting direct or indirect finan- 1 year 0 cial loss to the property inventory 0 2 4 6 8 10 12 14 discount rate (%) For a given hazard, catastrophe modeling Source: Hochrainer-Stigler et al. 2010. allows the costs and benefits of different DRM 1 8    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S FI G U R E 1.12  Mitigation benefit-cost ratio for wood frame building in Canaries, St. Lucia, with and without the effect of climate change a. In the absence of climate change b. Incorporating climate change benefit-cost ratio benefit-cost ratio 5 5 4 4 3 3 2 2 1 1 0 0 0 5 10 15 20 0 5 10 15 20 time (years) time (years) roof mitigation (A) opening mitigation (B) roof and opening mitigation (AB) Source: Ou-Yang 2010. Note: 0 percent discount rate assumed. in the absence and presence of climate change. Caribbean governments. It is designed to As expected, benefit-cost ratios increase with limit the financial impact of catastrophic hurricanes and earthquakes to Caribbean time in both cases, but grow faster in the pres- governments by quickly providing short term ence of climate change. This phenomenon is liquidity when a policy is triggered. It is the more significant for longer time scales. After world’s first and, to date, only regional fund 20 years, the benefit-cost ratio is above 4.5:1 in utilising parametric insurance, giving Carib- the presence of climate change, but slightly bean governments the unique opportunity to below 4:1 in the absence of climate change. purchase earthquake and hurricane catastro- phe coverage with lowest-possible pricing The role of disaster risk insurance (CCRIF 2012). How much to invest in risk reduction and how Consensus in this field suggests that insur- much to invest in insurance is a complex ques- ance by governments is not appropriate for tion. For risk reduction, investments are likely to have a better benefit-cost ratio for relatively frequent events than for infrequent low-prob- F IGUR E 1.13  Efficiency of risk management instruments and ability events. Risk insurance, on the other occurrence probability hand, is seemingly less economically rational for frequent low-loss events that may be cov- 500 year Very extreme losses: Residual risk unprotected as not e ective to reduce or transfer risks ered domestically or where the risk may be reduced (Mechler et al. 2010) (figure 1.13). return period There has been growing interest in poten- 100 year Medium-size to extreme losses: tial insurance vehicles for the relatively more Low to Risk financing extreme disaster risks (Kunreuther 2009). An medium-size more losses: Risk e ective example of one such vehicle is the Caribbean reduction more 10 year Catastrophe Risk Insurance Facility: e ective CCRIF is a risk pooling facility, owned, oper- Source: Mechler et al. 2010. ated and registered in the Caribbean for CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 9 frequently occurring risks; rather, expenditure development protected and adaptation to cli- on risk reduction is relevant in such circum- mate change facilitated. Rather than a cost, this should be seen as an investment in build- stances. Since MoSSaiC seeks to reduce land- ing a more secure, stable, sustainable and slide risk by directly addressing local urban equitable future. Given the urgency posed by landslide hazard drivers, it may play a role in climate change, decisive action needs to be reducing the accumulation of just such fre- taken now (UN 2009, 4; emphasis added). quently occurring events. MoSSaiC could also potentially have attractive benefit-cost ratios In the case of landslide risk, there is a need in reducing the landslide hazard associated to better understand landslide hazard drivers with more extreme rainfall events (Holcombe and provide a scientific basis for landslide risk et al. 2011). management. This means understanding the physical processes affecting slope stability Need for science-based risk assessment (and the effect of human activities on those The move toward investment in ex ante DRR physical processes) and the scale at which carries with it the need to assess and address they operate (the hillside/community scale), the underlying risk drivers—hazard, exposure, so that appropriate hazard reduction mea- and vulnerability (defined in section 1.3.2). sures can be identified and implemented. Rel- Risk assessment provides the basis for effec- evant landslide hazard drivers and assessment tive DRM by answering the following ques- methods are introduced in chapters 2, 3, and 4. tions and identifying what risk management The need for the geoscience disciplines to options will be most effective (Ho, Leroi, and inform an integrated approach to landslide Roberds 2000; Lee and Jones 2004):  risk reduction has been widely voiced: • Hazard identification. What are the likely While all regions experience landslide disas- ters, the harm they cause is most acute in types of hazards? developing countries, where the knowledge • Hazard assessment. What is causing each base required to identify landslide prone hazard, and what is the frequency and mag- areas is often either nonexistent or fragmen- tary (UNU 2006). nitude of that hazard? • Identification of elements at risk. What In order to mitigate landslide hazard effec- tively, new methodologies are required to are the elements exposed to each hazard? develop a better understanding of landslide • Vulnerability assessment. What might be hazard and make rational decisions on the the degree of damage to these elements? allocation of funds for management of land- slide risk… this relies crucially on a better • Risk quantification/estimation. What is understanding and on greater sophistication, the risk associated with each hazard? transparency and rigour in the application of science (Dai, Lee, and Ngai 2002, 65, 82). • Risk evaluation. What is the significance of these estimated risks, and what are the Scientific methods for assessing landslide options for managing them? hazard (location, frequency, magnitude) should be combined with an assessment of the The United Nations (UN) has provided vulnerability of those communities exposed to clear recommendations on the need for effec- the hazard, so that the most at-risk communi- tive risk assessment; these call for the underly- ties are identified. The UN’s specific recom- ing risk drivers to be addressed: mendations are as follows: A failure to address the underlying risk driv- • Shift the emphasis of social protection from ers will result in dramatic increases in disas- an exclusive focus on response to including ter risk and associated poverty outcomes. In pre-disaster mechanisms and more effec- contrast, if addressing these drivers is tive targeting of the most vulnerable given priority, risk can be reduced, human groups; [and] 2 0    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S • Promote a culture of planning and imple- The scale of the map is incompatible with the mentation of disaster risk reduction that scale of the physical processes. builds on government-civil society part- Ideally, the most appropriate use of these nerships and cooperation and is supportive of local initiative, in order to dramatically maps would be to enable the identification of reduce the costs of risk reduction, ensure planning control zones—preventing occupa- local acceptance, and build social capital tion or development of the most landslide- (UN 2009, 5; emphasis added). prone areas and thereby avoiding exposure to the hazard altogether. However, in developing Commentaries by Maskrey (1989), Pelling countries, there is often limited capacity for and High (2005), and Twigg (2001) all bear on enforcing planning controls or for removing the community potential in this context. Social people from such areas. funds are perhaps one example of the formal- If exposure of communities to landslide ization of this type of government–civil society hazards cannot be easily reduced, the next partnership, in that such agencies might be question is whether the hazard or its conse- well placed to contribute to MoSSaiC land- quences can be reduced. Unfortunately, wide- slide risk reduction implementation projects. area landslide susceptibility/hazard maps will not yield answers about what is actually caus- Need to complement national risk maps with ing slope instability on a particular hillside or local studies when a landslide might happen. Without such In the context of international and national an understanding, an appropriate mitigation DRM policies, a natural first step is to attempt approach cannot readily be identified. This to carry out a disaster risk assessment at a mismatch of scales may be one factor leading regional or national scale. This often involves to the observation that, despite numerous using geographic information system (GIS) major regional approaches, the uptake of haz- software to generate maps delineating broad ard maps has been minimal (Opadeyi, Ali, and zones of hazard, vulnerability, and risk. The Chin 2005; Zaitchik and van Es 2003). accuracy and spatial resolution of risk maps As noted, wide-area landslide hazard map- are determined by the quality and resolution ping represents the first step in the risk assess- of the underlying layers of data—multiple ment process. Having identified broad zones digital maps of the different variables that of landslide hazard, the next step is to move to affect hazard, exposure, and vulnerability. a more detailed scale—to go on site to identify For example, landslide hazard may be the local hazard drivers. In this way, MoSSaiC expressed qualitatively, and at low spatial involves communities and government teams resolution, as landslide “susceptibility” combining local knowledge and scientific according to general maps of slope angle, soil expertise to understand the local slope pro- type, and land use. cesses and identify potential landslide mitiga- In the last decade, there have been signifi- tion measures. Complementing existing wide- cant advances in spatially distributed landslide area landslide risk maps with this bottom-up analysis. Glade and Crozier (2005) review cur- approach can enable national DRM policies to rent qualitative and quantitative approaches to be translated into the delivery of effective mit- the analysis of landslides at scales ranging igation measures. from less than 1:10,000 to greater than The role of social funds 1:750,000. However, even at the most detailed spatial scales, GIS-based mapping methods In seeking to assist the most vulnerable com- are not able to identify detailed slope proper- munities, social funds have had a major role in ties and local landslide mechanisms. National many developing countries and have become landslide susceptibility or hazard maps devel- increasingly focused on vulnerability reduc- oped in this way are effectively decoupled tion as part of DRM. Such funds are often from the dominant local landslide processes. assimilated into government as institutions CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 1 and, in certain cases, are better integrated with ability drivers of landslide risk (such as pov- related regional funding agencies. The main- erty reduction or risk preparedness projects). streaming of social funds over recent years A flexible blueprint for landslide risk reduction (figure 1.14), combined with their focus on the policy and practice neediest, makes them a potentially important partner in addressing the physical and social MoSSaiC is designed to deliver effective land- drivers of landslide risk. slide risk reduction measures by Social funds can assist in DRM and contrib- • applying appropriate scientific methods (at ute to elements of disaster risk insurance in the correct physical scale) for understand- the following ways (Siri 2006): ing the physical risk drivers and hence • Setting standards of best practice in infra- reducing the landslide hazard; structure construction • doing so within the context of the commu- • Setting an example by not promoting nity, while encouraging a government-com- rebuilding in hazard-prone zones munity partnership for both the delivery of the measures and ongoing management of • Delivering training activities aimed at slope stability; and thereby strengthening technical capacity to miti- gate the potential impact of natural disas- • providing a basis for development of an evi- ters dence base that mitigation can pay— socially and economically, directly and indi- • Broadening their portfolios to include dam- rectly. age mitigation projects for landslides MoSSaiC assesses the specific landslide risk • Promoting microcredit programs faced by vulnerable communities in two • Generating employment to low-income stages: (1) by using basic risk indicators to groups, thereby reducing the vulnerability identify the most at-risk communities (utiliz- of the poor to disasters. ing any available wide-area landslide suscepti- bility or hazard maps and community vulner- While the MoSSaiC approach is essentially ability assessments); and (2) by undertaking focused on addressing the physical landslide detailed slope feature mapping at the commu- hazard drivers in the most vulnerable com- nity scale so as to understand the precise land- munities, it is important to couple such an slide mechanisms. In densely populated vul- approach with any existing local initiatives nerable communities, infiltration of surface aimed at assessing and addressing the vulner- water is often a significant factor in causing F IG U R E 1 .1 4  Evolution of social fund objectives and activities Late 1980s 1990 Late 1990s 2000 Late 2000s Employment/crisis Centrally driven CDD approaches Support for Agencies take on response infrastructure/ decentralization/ added responsibilities social service CDD/microfinance (such as CCT/ development disaster management) Increased integration into country’s poverty Temporary funds reduction efforts and mainstreaming as legitimate institutions of government Source: de Silva and Sum 2008. Note: CCT = conditional cash transfer; CDD = community-driven development. 2 2    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S landslides. Treatment of this hazard involves Landslide-triggering rainfall and climate change designing and constructing drains in key loca- tions to capture surface water; this is under- Many developing tropical and subtropical taken by government teams and community regions are subject to rainfall events that trig- contractors. Evidence of the effectiveness of ger landslides on steep slopes. Certain current the hazard reduction measures is evaluated. climate change predictions point to the likeli- The role of the government in addressing both hood of an increase in the intensity of hurri- the physical and social risk drivers, and at the canes and other extreme rainfall events in correct scale (hillside/community level), is those regions, which could be expected to vital. result in an increase in the number and magni- This approach to community-based land- tude of landslides (Mann and Kerry 2006). slide risk reduction is discussed more fully in The links between climate change, devel- section 1.4. Indeed, this book as a whole aims opment, and DRR are strongly emphasized by to provide a flexible blueprint for this form of international development agencies. For landslide risk management. example, the United Nations International Strategy for Disaster Reduction notes that 1.3.4 Landslide risk and other “Disaster risk reduction and climate change development policy issues mitigation and adaptation share common A range of development policy issues and pro- goals. Both fields aim to reduce the vulnerabil- cesses can result in intensified landslide occur- ity of communities and achieve sustainable rence, including climate change, urbanization, development” (UNISDR 2012). This bolsters land-use practices (deforestation, cutting of an earlier statement that “the impact of any slopes for housing construction), and inade- increases in weather-related hazards will be quate management of water and sewage sys- highly asymmetric. Poorer countries that con- tems. Two such issues are useful to introduce centrate most existing risk will be dispropor- at this stage because of their connection to the tionately affected by climate change” predominant landslide risk drivers MoSSaiC (UNISDR 2009, 20). seeks to mitigate. Where possible, predicted changes in the recurrence intervals of landslide-triggering • Some predictions (e.g., UNISDR 2009) rainfall events should be incorporated in land- maintain that climate change may cause an slide hazard assessment. The risk of not doing increase in the intensity of rainfall events in so may leave a significant public liability, either the humid tropics. Knutson et al. (2010, 157) because the private sector will no longer bear additionally comment that “it must be the risk or due to the increased costs of disas- acknowledged that trend detection is ham- ter recovery (UNISDR 2009). In some cases, pered by the substantial limitations in the even relatively simple structural measures availability and quality of globally available could yield both short- and long-term benefits data.” Because rainfall is one of the physical to climate change. Because such measures drivers of landslide hazard, it is possible could include landslide mitigation, MoSSaiC is that climate change could increase the fre- consistent with this policy agenda. quency of rainfall-triggered landslides in this region. Urbanization • Urbanization is a major socioeconomic Societal change is more rapid than climate driver with respect to landslide risk. As change. Four important societal drivers pro- noted above, the activity of developing vide a critical context for the accumulation of landslide-prone slopes can increase land- landslide risk: a significant rise in the global slide hazard, while those living on the population (figure 1.15a), accompanied by slopes tend to be the most vulnerable to increased urbanization (figure 1.15b) and poor such disasters. housing (figure 1.15c), which results in the CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 3 most vulnerable having the greatest exposure F IG U R E 1 .1 5  Population growth and to landslide risk (figure 1.5). urbanization drivers of landslide risk Slums will grow on marginal urban land a. Global population growth because the speed of economic growth in billions urban centers is not keeping pace with the 9 combined impact of increasing population and rural-to-urban migration. People move to total world population urban centers hoping to capture a place in the 6 new economy. But this urban inflow outruns the capacity of private employment generation developing countries 3 and government capacity to create infrastruc- developed countries ture (Spence 2011). Housing tenure is also relevant in this con- 0 text. The World Bank (2009) reports that for 1750 1800 1850 1900 1950 2000 2050 low-income countries, the predominant hous- ing tenure is unauthorized (defined by Angel b. Urban/rural population shift 2000 as not in compliance with current regu- lations concerning landownership, land-use percent 80 and planning zones, or construction), with rural share of world population small amounts of squatter housing (table 1.5). 65 The following urbanization factors serve to increase landslide risk: 50 • In many locations, the amount of unauthor- 35 ized housing (approximately 60 percent in urban share of world population areas of the Eastern Caribbean, e.g.) exceeds 20 that of authorized housing. Planning and 1950 1970 1990 2010 2030 associated zoning policies can be expected to have a limited impact in such circum- stances. c. Growth in slum population • Unauthorized or informal housing is often billions 1.50 located on already landslide-prone slopes. Latin America and the Caribbean While typical slope zoning requirements 1.25 for a landslide-prone area suggest that no houses should be built on slopes that exceed 1.00 World more developed 14 degrees (Schuster and Highland 2007), regions 0.75 informal housing settlements are invariably Asia North on hill slopes that are considerably steeper. Africa 0.50 • Unauthorized housing may contribute to 0.25 Sub-Saharan Africa slope instability if residents 0 —— cut slopes at steep angles to provide 1990 1995 2001 2005 2010 2015 2020 benched slopes for additional housing; Sources: a—Soubbotina 2004; b—UN 2007; —— redirect storm runoff so flows are con- c—UN-Habitat 2005. centrated onto portions of slopes that Note: In c, figures for 1995 are interpolated using estimates for 1990 and 2001. Figures for 2005 are are not prepared to receive them; projections. Australia, New Zealand, and Japan are included in the more developed regions. —— add water to slopes from septic systems; or 2 4    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S TAB L E 1.5  Percentage of owner occupancy, unauthorized housing, and squatter housing by country income group, 1990 LOWER-MIDDLE UPPER-MIDDLE HOUSING TENURE LOW INCOME INCOME INCOME HIGH INCOME Owner occupancy 33 59 57 59 Unauthorized housing 64 27 9 0 Squatter housing 17 16 4 0 Source: World Bank 2009. —— remove trees, shrubs, and other woody slide-risk reduction, in which community vegetation (Olshansky 1996). residents indicate areas of perceived drain- age problems before assessing options for • The numbers of people living in unauthor- reducing land­slide risk by managing surface ized housing areas have grown very rapidly. water. In Caracas, República Bolivariana de Vene- The activities? Managing surface water in all zuela, it has been estimated that about forms (roof water, gray water, and overland 40  percent of the population lives in low- flow of rainfall water), monitoring shallow ground­water conditions, and constructing income districts (barrios) that grow at an low-cost drain systems. All the work is bid annual rate of about 20 percent (Schuster out to contractors in the com­ munity. This and Highland 2007). end-to-end community engagement encour- ages participa­tion in planning, executing, and The trends in increasing unauthorized maintaining surface water manage­ ment on urban development and landslide risk will high-risk slopes. It produces a program owned by the community rather than continue unless effective mitigation measures imposed by the agency or government. are delivered on the ground. An attendant MoSSaiC has lowered landslide risk by offer- issue for governments to consider is the degree ing the community employ­ ment and risk to which they would regard the construction awareness—and has taken a participatory of landslide mitigation measures as legitimiz- approach to rolling out the program to other ing unauthorized communities in such cir- com­ munities. The program shows that cumstances. This is an issue that would need changing community views of hazard mitiga- to be reviewed when any such project is con- tion can enhance community perceptions about climate risks. It also establishes a feed- sidered for implementation. back loop between project inputs and out- puts, with more than 80 percent of funds spent in the communities, allowing commu- 1.4 MOSSAIC nities and governments to establish a clear link between risk perceptions, inputs, and tangible outputs (World Bank 2010a, 327). 1.4.1 Overview In contrast to more top-down approaches, The 2010 World Development Report provides MoSSaiC has been developed at the scale of this overview of MoSSaiC: communities and hillsides, thus accessing A new way of delivering real landslide-risk community information and slope parameters reduction to vulnerable com­ munities was at a process-relevant scale. This approach piloted by MoSSaiC, a program aimed at enables engagement with residents and gov- improving the management of slopes in communi­ ties in the Eastern Caribbean. ernment experts (including engineers, survey- MoSSaiC identifies and implements low- ors, planners, and community development cost, community-based approaches to land- officers) in order to develop a comprehensive CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 5 assessment of likely landslide triggers, the level These three foundations—combining of hazard, and potential impact. Typically, the research, policy, and humanitarian interests to dominant instability mechanism in these deliver evidence for undertaking mitigation densely constructed communities is the infil- and for establishing postmitigation out- tration of rainfall and household water into the comes—require a functional holistic structure slope material—and the concentration of such (figure 1.16). The following chapters detail the flows at landslide-prone locations due to various elements within this structure. altered surface water runoff and slope drainage patterns. Landslide hazard mitigation mea- 1.4.2 MoSSaiC: The science basis sures therefore consist of appropriately located A landslide risk assessment with an appropri- drains to intercept and control surface water, ate scientific basis provides the foundation for the capture of roof water, and the connection of designing an intervention and allows those households to the drainage network. advocating the measures to justify their rec- As introduced in section  1.2, MoSSaiC is ommendations. An understanding of the based on three key foundations (table 1.6)—a mechanisms that trigger landslides and the scientific base that, combined with a commu- scale at which they operate is thus essential. nity base, delivers the evidence base for land- The drivers of landslide risk can be summa- slide mitigation. Management and clear com- rized as follows. munication of this approach, within government and in partnership with the com- • Physical drivers. Landslide hazard results munity, can result in behavioral change from a combination of preparatory factors regarding slope stability practices and policies. relating to slope geometry, soil and geology, TAB L E 1.6  The foundations of MoSSaiC FOUNDATION EXPLANATION MoSSaiC Science base Need to understand the • Identifies localized physical causes of landslide hazard at the correct physical physical drivers for landslide scale (this coincides with the community scale and slope management hazard in order to design practices) appropriate mitigation • Addresses physical causes of landslides at this scale measures • Provides scientifically based justification for community selection and mitigation measures Community base Need to understand the • Focuses on the most vulnerable communities human risk drivers (as they • Engages with the community to identify landslide hazard causes and relate to both the physical solutions, often related to drainage hazard and to vulnerability) and balance government • Employs contractors and workers from the community to construct the policy approaches with drainage measures community-based • Recognizes the role of individuals in reducing landslide risk participatory solutions • Builds in-house teams of managers and expert practitioners to work with communities and deliver the mitigation measures • Encourages government-community partnerships Evidence base Need to provide evidence • Delivers appropriate physical works to reduce landslide hazard that landslide mitigation • Delivers the majority of project funding and time in the most vulnerable pays communities • Demonstrates the benefits and cost-effectiveness of community-based landslide risk reduction to decision makers • Changes the local risk perception and encourages behavioral change with respect to sustainable management of slope stability in communities 2 6    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S FI G U R E 1.16  MoSSaiC architecture—integrating science, communities, and evidence SCIENCE BASIS Slope mapping of landslide hazard factors: Hazard assessment—qualitative and · local slope geometry and surface drainage quantitative modeling to: angles, heights, lengths, convergence · define the hazard · soils and geology landslide likelihood or probability strata, depth, strength, and drainage properties (frequency), location (magnitude) · surface cover and loading · understand the hazard vegetation, structural loading, point water sources landslide hazard causes and solutions Slope mapping of exposure and vulnerability factors: Vulnerability assessment: · elements exposed to potential landslides · describing the vulnerability house locations, number of persons, house construction n elements affected, potential damage Community: · vulnerability of elements (different measures) · understanding the vulnerability leaders, damage potential (0–1), socioeconomic vulnerability local construction practices, vulnerability organizations, · cost of a landslide drivers residents, direct loss ($), indirect loss ($), intangible loss contractors Government: Landslide risk assessment management, Determine landslide risk as a function of hazard, exposure and vulnerability for each experts, community technicians, practitioners Landslide risk management Prioritize communities, design hazard reduction interventions, calculate costs and benefits of different options Implement hazard reduction measures: Audit outputs and outcomes: · community engagement · technical/physical effectiveness consensus, awareness, communication observed hazard reduction, construction quality · construction · cost-effectiveness local contractors, materials, training, project efficiency, benefit-cost ratio supervision · behavioral change increased awareness, capacity, good practice COMMUNITY BASIS EVIDENCE BASIS vegetation, surface water and groundwater infrastructure, changing the vegetation, regimes, and triggering mechanisms such as and consequential changes in slope surface rainfall and seismic events. Tropical regions water and groundwater regimes. The pres- are especially susceptible to landslides sure of development and population growth because of high-intensity and -duration on available land means that the poorer, rainfall in the context of the deep soils (often most vulnerable sections of society are liv- on steep slopes) in such environments. ing on the most-marginal, landslide-prone hillsides (figure 1.17). • Anthropogenic contributors. Even with- out climate change, anthropogenic activi- MoSSaiC is designed to address a very sig- ties are increasing landslide risk in some of the most vulnerable urban communities in nificant subset of landslide types: rotational developing countries. These activities and translational slides in predominately include altering slope geometry with earth- fine materials (soil) that are principally trig- works (cut and fill at the scale of household gered by rainfall. plots), loading slopes with buildings and CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 7 historical and biophysical data” (Zaitchik and F IG U R E 1 .1 7  Housing stock can reflect van Es 2003, 267). community vulnerability One reason for the lack of application of wide-area landslide maps is that they fail to capture many of the physical landslide hazard drivers that occur at a more detailed scale, and so cannot be used to develop physical land- slide hazard reduction measures. Highly local- ized slope features and processes, such as vari- ations in soil type and depth, and soil water convergence, can be critical landslide prepara- tory factors or triggers. These physical pro- cesses operate at scales that are many orders of magnitude smaller than those at which wide- area hazard maps can be resolved. Indeed, maps of soil depths are usually not even avail- able. Some of these parameters need to be resolved at the household scale (1–50  m2). Since identification of landslide mitigation measures can only come from knowledge of a. Because properties such as this can essen- tially be built in a weekend, effective urbaniza- local slope processes pertaining to the poten- tion of slopes can be very rapid. tial landslide trigger, MoSSaiC is designed to look within communities to examine and model the specific human and physical pro- cesses driving the landslide hazard. Landslide risk reduction measures must have a scientific basis The first stage in developing the scientific foundation for landslide risk reduction in communities is to acknowledge the highly localized scale of the physical and human haz- b. Property abandonment can further ard drivers. MoSSaiC therefore takes landslide complicate the issue of land and property titles hazard mapping into the communities. Chap- in vulnerable communities. ter 5 provides guidance on how to do this. The objective of community-based mapping is to observe and scientifically interpret slope fea- tures and processes, and to consider how they Understanding the risk drivers at the local scale vary over both time and space. This analysis Conventional top-down risk reduction initia- should be done at a scale that is capable of tives typically focus on wide-area (100– revealing the precise mechanisms determin- 1,000  m2) mapping techniques which can be ing the stability of the slope; this will enable used to identify zones of landslide susceptibil- identification of the potential mechanisms by ity based on the overlay and indexing of topo- which slope stability can be improved. graphic, soil/geology, and vegetation maps. In densely populated unauthorized hous- However, “management-oriented hazard ing communities, it is essential to identify the models have been applied in the developing effects of highly localized surface water world only rarely and with mixed success…in regimes, built structures, and cut slopes. Slope large part because of the limitations of relevant hydrology is one such landslide hazard driver 2 8    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S with a high spatial and temporal variability. ery time, benefit-cost ratios, scientific basis, The surface and groundwater regimes in such and sustainable policy uptake. The approach locations will vary over short time scales in goes a long way to reconciling the scale issues response to rainfall events and the addition of and risk drivers (discussed above) encoun- household water to the slope. Slope instability tered in delivering effective landslide risk is often increased where metered water is sup- reduction. plied to households in the absence of any sur- The aim of MoSSaiC is to engage with the face water drainage. In the Caribbean, where community, recognize its vital role in under- housing density can approach 70 percent of standing and managing slope stability, and the slope surface cover, the effect is to nearly build its capacity to do so. Simultaneously, the double the amount of surface water going onto community becomes the classroom for the the slope compared with that of annual rain- government teams to exercise their own fall (Anderson and Holcombe 2006). expertise, develop partnerships with the com- MoSSaiC employs a different approach to munity, and establish good technical and man- that used in generating wide-area hazard agerial practices with respect to landslide risk. maps. Landslide hazard mapping is carried All too often, “aid flows from those who out at a much more detailed scale (1:500 or happen to be strong, to those who happen to more) so that specific locations of landslide be weak, reflecting an inherently unbalanced hazard can be identified and the physical driv- power relationship” (Curtis 2004, 422). An ers understood. This understanding of physi- example of such an imbalance was identified cal landslide drivers underpins design and by Green, Miles, and Svekla (2009) in an analy- implementation of appropriate hazard reduc- sis of the institutions involved in DRR in the tion measures. most vulnerable settlements in Guatemala So, while large-scale landslide hazard maps City. The relationship among the stakeholders, generated as a result of top-down government shown in figure 1.18, suggests that policies may provide an indication of approxi- [T]here are minimal opportunities provided mate landslide zones, MoSSaiC practitioners by external actors to precarious settlement must work at the highly resolved spatial scales residents to influence the allocation of funds coincident with the dominant slope process used in improving the settlements…quite lit- controls. This requires observation and inter- erally, money flows around the precarious settlements, but not directly into them pretation of slope processes on the ground, (Green, Miles, and Svekla 2009, 53). with the support of appropriate scientific tools, in order to provide a scientific basis for Such imbalances are within a context of delivering landslide risk reduction measures potential network instability, with a small in communities. change in that context (e.g., political turnover) potentially causing the network to collapse. The MoSSaiC methodology is intended to MoSSaiC aims to redress such imbalances reduce existing landslide risk and not to affecting vulnerable communities by affirming and strengthening the community focus for encourage, and provide for, the construc- risk reduction. For MoSSaiC, “community tion of houses on slopes deemed landslide based” means engaging and working with prone. communities to jointly find and deliver solu- tions to landslide risk. 1.4.3 MoSSaiC: The community basis Learning from communities Residents influence the key variables underly- With top-down advocacy and managerial sup- ing the complex system of landslide risk and port, local-scale landslide risk reduction can disaster occurrence. A San Salvador slum have tangible benefits in terms of project deliv- dweller acknowledged the constant efforts CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 9 FI G U R E 1.18  Stakeholder connections in Guatemala City’s precarious settlements, showing how money flows around, but not into, the settlements Settlement risk assessment Settlement advocacy/lobbying Nongovernment Donors Informal Private NGOs sector sector Labor Settlement advocacy/ Labor Materials Development lobbying regulations, Infrastructure Services, taxes repair, Infrastructure, infrastructure revegetation, materials, Residents emergency information planning Legal Settlements Infrastructure, neighborhoods Access legalization, and downstream capacity building, issues Lobbying food for legalization Development CIV regulations, (Ministry of Communications, taxes Infrastructure and Housing) Services, Settlement infrastructure Votes risk Votes assessment Government Development CONRED Central SEGEPLAN regulations (National Coordinating Agency (Presidential Secretariat for Municipalities for Disaster Reduction) government Planning and Programming) Special project Special project requests rankings money Development banks, oversight international Ministry of Finance services assistance, taxes Source: Green, Miles, and Svekla 2009. individuals make in coping with disasters and (and increasing) risks such as landslides, disaster risk: “We are always trying to improve, understanding the concerns of the residents is little by little, step by step, in order to become critical. In this respect, identification of the more secure” (Wamsler 2007, 118). landslide hazard and appropriate landslide Household strategies to reduce risk are risk reduction measures properly begins with diverse and include physical/technological, learning from communities (figure 1.19). environmental, economic, social/cultural, This learning process must extend to organizational, and institutional measures understanding the way in which the commu- (table 1.7). nity functions and how MoSSaiC can best be Because such DRR activity may be taking applied in that context. The guidance and place in a vulnerable community at the house- methods presented in this book should serve hold level, it is important to establish the as a flexible blueprint toward this end. degree of this activity and build on it through Identifying the most sensitive and effective MoSSaiC. As Rayner and Malone (1997, 332) means for engaging with each community will note, “adaptation is a bottom-up strategy that also provide the best opportunity for residents starts with changes and pressures experienced to “own” the project and adopt good slope in people’s daily lives.” Whether a community management practices for themselves (fig- is adapting to climate change or to existing ure 1.20): 3 0    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S TAB L E 1.7  Coping mechanisms deployed by individual residents in vulnerable communities to reduce landslide risk FOCUS/AIM ACTIVITY IDENTIFIED • Increasing inclination of roofs (for better runoff without damaging roof constructions) • Prolonging roof projections/eaves (to protect houses and pathways from damage/erosion) • Changing direction of roof inclination (so rainwater is discharged without causing damage/landslides) • Installing provisional gutters as roof eaves (so rainwater is discharged without causing damage/landslides) • Replacing mud walls with brick walls, wooden pillars with metallic ones, and corrugated iron with more Constructive durable materials (to better withstand earthquakes, rain, and/or floodwater) structural house • Regularly replacing corrugated iron, wooden pillars, and beams (to better withstand rain or earthquakes) improvements • Improving roof fittings (to better withstand earthquakes and windstorms) • Regularly covering walls and floors with (additional) cement (for better runoff without causing damage/erosion) • Filling cracks with cement (for better runoff without causing damage/erosion) • Closing holes in corrugated iron sheets using special fillings or patches on top of or under sheets (to prevent water entering the house) • Changing the locations of latrines and wash places (to mitigate landslides) • Blocking wastewater pipes with stones and other objects when river levels rise (to avoid flooding and/or related contamination) Nonconstructive • Putting wood or bricks on the roof (to hold it in place during high winds) nonstructural • Putting plastic sheets on the roof, on the inside walls, or over the bed (to prevent water entering or house damaging the house) improvements • Building water barriers in front of the house (to prevent water entering the house) • Digging water channels in earth floors inside the house (for better runoff without causing damage/erosion) • Putting pots under roofs with holes (to catch water, preventing damage/erosion) • Strengthening pathways by covering them with (additional) cement and filling cracks (to mitigate landslides and minimize damage caused by rain and earthquakes) • Filling in former latrine holes with earth, stones, and/or cement (to mitigate landslides and minimize damage caused by rain and earthquakes) Constructive • Repairing public infrastructure that passes through the settlement, such as wastewater pipes (to avoid structural flooding and related contamination) improvement of • Building provisional water channels with corrugated iron or cement (to discharge rainwater without causing the surrounding damage/landslides) living • Building fences to hold back soil (mitigating landslides) and/or to prevent children from falling (fences are environment made of corrugated iron, mattress springs, wooden pillars, and wire netting) • Compacting soil (to mitigate landslides and minimize damage caused by rain and earthquakes) • Building retaining walls or embankments from old tires, stones, and cement; old tires and soil; bricks and cement; stones only; nylon bags filled with soil and cement; and other materials (to mitigate landslides and minimize damage caused by earthquakes) • Putting plastic sheets on slopes, often during entire year (to mitigate landslides) Nonconstructive nonstructural • Digging water channels in earth outside the house (to discharge rainwater without causing damage/landslides) improvement of • Avoiding obvious flood- or landslide-prone locations for house expansion the surrounding • Replacing eroded earth with new earth (to mitigate landslides and minimize damage caused by rain and living earthquakes) environment • Cleaning water gutters (to mitigate flooding) Use of natural • Planting vegetation to prevent landslides resources to reduce risk Removal of • Cutting down bigger branches and trees located close to houses (to minimize the risk of them falling down natural resources and causing damage during earthquakes and landslides) representing risk Cleanup of • Cleaning waste from slopes (to mitigate flooding caused by blocked water gutters) natural • Replacing eroded earth with new earth (to mitigate landslides and minimize damage caused by rain and environment earthquakes) Source: Wamsler 2007. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 1 causality of landslide risk, which is intrinsi- F IG U R E 1 .1 9  Learning from community cally linked to the activity of individual house- residents holds in terms of water and slope management practices. There is no blanket solution, as top- down hazard mapping approaches so often implicitly suggest. For this reason, the knowl- edge of all community members is vital in gaining an understanding of the highly local- ized slope processes leading to landslides. Working toward community-owned solutions A critical component of the MoSSaiC method- ology is to discuss with residents why land- It is important to spend time in communities talking with residents and learning from them slide risk drivers can vary over short distances, about their perceptions of risk and of any and therefore why they should expect that dif- landslide occurrences within the community, ferent hazard reduction measures may be however minor. needed on different parts of the hillside. Understandably, householders are anxious that they will tangibly benefit from such mea- F IG U R E 1 . 2 0  Effects of prompt and sures and will need reassurance, for instance, informed action that a drain built upslope of their house will actually help them even if it is not on their property. That such a decision (the design of the community drainage system) is not an imposed solution, but one that the community has taken ownership of from the beginning is important—not least for residents in vulnera- ble communities who are too often the sub- jects of development rather than active par- ticipants in the process. Numerous methods exist for community Prompt drainage action by the owner, taken participation, but they need to be adapted to while a major landslide rose halfway up the the local context; nearly all require facilitation house’s rear wall, undoubtedly saved this and other forms of support from the govern- property from being lost. The resident had reported earlier minor slides in the same ment or from nongovernmental organizations location. (NGOs). Transparency and effective commu- nication are essential to maintaining engage- ment and credibility with and within the com- A community-based approach aims to reduce their socially constructed vulnerability by munity during the reconstruction process. involving communities as active participants Engaging the community in a disaster program. There is also a broaden- ing consensus that it is cost-effective to train A good risk reduction strategy engages com- and educate communities about risks they munities and helps people work together to face, provide them access to resources and minimize risk. Participation should be by the knowledge, and to develop community-based preparedness and mitigation programs (World entire community, particularly women, young Bank 2007). people, and all livelihood groups—a point that should be clearly communicated to the com- Such considerations are important in munity. Community engagement is valuable understanding the precise physical and social for the reasons given in table 1.8. 32    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S TAB L E 1.8  Value of community engagement VALUE EXPLANATION Allows community Community-based approaches require a somewhat different programming knowledge and scientific flow that begins with mobilizing social groups and communities and having understanding of hazard them fully involved in the risk assessment process and vulnerabilities to be combined Reveals community “The community” is not a monolith, but a complex organism with many subgroups alliances and subgroups; it needs to be engaged in order to identify concerns, goals, and abilities, but there may not be consensus on these items Provides high-resolution The scale at which community engagement is most effective may be quite information small—for example, as few as 10 families; individuals may contribute valuable information on landslide processes at the scale of 1–50 m2 Can reveal different Engagement of the community may bring out different preferences and perceptions to those of expectations, so agencies involved must be open to altering their precon- government ceived vision of the landslide risk management process Builds skills within the Strengthens community skills and capacity for assessing landslide risk, community constructing drainage measures, maintaining the intervention, and developing sustainable slope management practices; training can play an important role in building a community’s capacity to take on project responsibilities Delivers social outcomes Empowers individuals, increases local capacity, strengthens democratic processes, and gives voice to marginalized groups Assists program Creates a sense of ownership, improves program quality, mobilizes resources, effectiveness and stimulates community involvement in execution Source: World Bank 2010c. Participation empowers communities; how- • infuse political issues at the national level ever, the outcomes of that participation can be into the proposed community project. unpredictable. The participatory process may Other behaviors possibly arising during dis- • give rise to new actors and stakeholders; cussions with community residents are that • create conflicts among organizations that community members may not be immediately had previously worked together harmoni- forthcoming with their perspectives, may ously; downplay the significance of threats, or may reserve judgment until they see something • give a platform to vocal individuals whose tangible (UNDP 2008). views are not shared by the majority; Communities participate in MoSSaiC proj- • inflame preexisting, but hitherto dormant, ects through five activities: tensions within the community; • Provision of information on slope features • raise expectations beyond delivery possi- and landslide hazard bilities, insofar as community perceptions • Organization of community meetings and may differ from information residents are coordination with government teams actually given; • Involvement in identifying the landslide • engender “mirror politics,” with commu- hazard reduction measures nities potentially feigning agreement in order to divert opportunities to other ends; • Construction (possibly also including con- and tracting and procurement) CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   33 • Monitoring and maintenance of landslide bilities, and new ideas for activities and mitigation measures projects emerge. Trained facilitators and other experts in community participation should be Building government capacity part of the MCU to ensure such synergies. Governments often have sufficient technical and managerial skills that can be harnessed to 1.4.4 MoSSaiC: The evidence base design and deliver landslide risk reduction Decision makers need an evidence base in measures in communities. By creating a cross- order to endorse expenditure on landslide risk disciplinary management unit from such a skill reduction and adopt a proactive ex ante policy base, it is possible to embed MoSSaiC in gov- approach. A typical MoSSaiC project that ernment practice and policy. Chapter 2 is tackles the root causes of landslide hazard will focused on how such a management team— have measurable short-term outputs and lon- here referred to as the MoSSaiC core unit ger-term outcomes (table 1.9). (MCU)—can be built. It identifies the types of Types of evidence in-house expert practitioners needed for implementing the various tasks. The methods This book emphasizes the need to identify and tools provided in this book can be adapted evidence of longer-term benefits of landslide to suit the government’s structures, protocols, risk reduction in communities—the actual and practices. The aim is that governments reduction in the hazard, and the direct and adapt and adopt MoSSaiC in a way that can be indirect benefits (financial and social). The sustained and embedded in local practice and delivery of physical landslide risk reduction policy. measures provides the opportunity to observe the benefits in terms of potentially avoided Clear communication in government- landslide occurrence and losses. This form of community partnerships evidence is counterfactual and often anecdotal, Organizing and facilitating community partic- since it is not know what would have happened ipation should not be done on an ad hoc basis. if the physical measures had not been in place. “Unless risk analysis and communication are However, it is still a powerful means of adequately factored in, major differences in demonstrating the benefits of the intervention. perceptions of risk can impede successful pol- Slope stability modeling can provide a means icy design and implementation” (World Bank for quantifying the reduction in the frequency 2010a, 325). It is important to guide the par- or magnitude of landslides. These model ticipation process and make sure that people’s predictions can then be related to the value of expectations are realistic, especially if they the losses avoided (a project benefit) and believe that large amounts of funding are avail- compared with project costs. Less-tangible able. Community-based projects require social benefits and changes in slope thoughtful engagement on the part of the gov- management practice should also be captured. ernment: Chapter 9 presents some potential methods Information, education, and awareness-rais- for developing this evidence base and ing as carried out so far, are at best not enough identifying the extent of behavioral change. to spur people into action and at worst coun- MoSSaiC project outcomes from sample ter-productive… This calls for a different interventions completed in St. Lucia and Dom- approach, where the individual is considered inica are outlined in table 1.10. not merely the passive receiver of informa- tion but an agent in both causes and solutions 1.4.5 MoSSaiC project components (World Bank 2010a, 327). There are nine principle MoSSaiC project When a government-community partner- components, as reflected in the chapters in ship is well configured, there can be a multi- this book. While seven are sequential plier effect as the community realizes its capa- (figure  1.21), two (encouraging behavioral 3 4    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S TAB L E 1.9  Basic MoSSaiC outputs and outcomes providing evidence for ex ante landslide mitigation BASIC OUTPUTS AND OUTCOMES MEASURE (EVIDENCE BASE) Quantities Quantity of physical measures constructed, funds disbursed, persons employed, etc. Direct physical benefits: landslide hazard Observation and local knowledge relating to the effect of heavy reduced rainfall events post-intervention (qualitative) Project Modeled/predicted stability of slope for before and after outputs scenarios (quantitative) Additional physical and social benefits to com- Observation and local knowledge relating to the effect of heavy munity: reduced localized flooding, less mud rainfall events post-intervention (qualitative) on paths, improved water supply through Cost-benefit analysis of project rainwater harvesting, improved environment Evidence of behavioral change Institutional uptake of ex ante approach to managing slope stability in communities based on scientific understanding, Longer-term community focus, and evidence of effectiveness project outcomes Community uptake of good slope management practices based on understanding of local slope processes and demonstration of tangible benefits change and project evaluation) are crosscutting These provide the framework for each chapter components relevant from the start of any and are outlined in table 1.11. proposed MoSSaiC intervention and continuing through to the postproject period. 1.4.6 MoSSaiC pilots The nine components can be subdivided MoSSaiC was initially developed and applied into a series of steps that deliver MoSSaiC. in the Eastern Caribbean (table 1.12). Fig- TAB L E 1.10  Broad impacts of community-based landslide risk reduction program in St. Lucia and Dominica, 2005–10 CATEGORY INDICATOR IMPACT (IN 11 COMMUNITIES) Hazard reduction Pre-MoSSaiC: Minor and major failures during low-recurrence-interval events (~1 in 3–5 Physical year 24 hour) with loss of houses in some communities Post-MoSSaiC: No reported failures from Hurricane Tomas (~1 in 500-year 24-hour rainfall event) Project expenditure ~80% of funds spent on materials and community labor profile Intervention cost equates with approximately 2.3% of community relocation costs should a major landslide occur Economic Average cost per community resident ~$250 ~1,000 person-weeks employment for community members Benefit-cost ratio >2.7:1 in a selected community Persons involved Number of households ~750, number of residents ~4,000 Community construc- Residents share with government in terms of design, construction, and, in some cases, tion partnerships cost Community Water supply continuity 450-gallon water tanks supplied to most-deserving residents in selected communities Certification of key A MoSSaiC certification system, resulting in award to three members from different community members communities for their commitment, leadership, and understanding of the MoSSaiC vision Public Media recognition St. Lucia, Dominica, St. Vincent and the Grenadines: TV/radio interviews, news coverage awareness St. Lucia TV 30-minute MoSSaiC documentary commissioned by government Source: Anderson et al. 2010. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 5 F IG U R E 1 . 2 1  MoSSaiC components 1 Foundations: reducing landslide risk in communities 2 Project inception: teams and steps 3 Understanding landslide hazard 4 Selecting communities 8 Encouraging 9 Project behavioral evaluation 5 Community-based mapping for landslide change hazard assessment 6 Design and good practice for slope drainage 7 Implementing the planned works ure 1.22 provides an indication of typical vul- the World Bank (2010b) has assessed the impact nerable urban communities and landslide risk of disasters on GDP over a 40-year period. For drivers in this region. many countries, this impact exceeds 1 percent of Many of the countries in the region are par- GDP; notably, many SIDS fall into this category. ticularly vulnerable to natural disasters The vulnerability of this region is con- (figure  1.23). To enable country comparisons, firmed by the United Nations: TAB L E 1.11  MoSSaiC framework CHAPTER COVERAGE OUTPUT 1. Understand the disaster risk context with respect to landslides Relevance of MoSSaiC 1. Foundations: 2. Understand the innovative features and foundations of MoSSaiC approach to local Reducing landslide risk context Landslide 3. Identify general in-house expertise and the appropriate institutional structures for identified Risk in codifying a local approach toward landslide risk reduction Communities 4. Brief key individuals on MoSSaiC (politicians, relevant ministries, in-house experts) Core unit of team members identified 1. Establish the MCU; define and agree on key responsibilities MCU formed • Identify available experts in government • Form the MCU and establish communication lines with government 2. Identify and establish government task teams; define and agree on key responsibilities Government task • MCU to identify individuals from relevant ministries to form government task teams formed teams (mapping, community liaison, engineering, technical support, communica- 2. Project tions, advocacy) Inception: • Define roles and responsibilities of the teams Teams and Steps 3. Identify and establish community task teams; define and agree on key responsibilities Community task teams • MCU to identify individuals from selected communities to form community task formed teams (residents, representatives, construction teams) • Define roles and responsibilities of the teams 4. Agree on a general template for project steps Project steps deter- • Review project step template and amend as necessary mined and responsibili- ties assigned • Assign team responsibilities to relevant project steps; confirm project milestones (continued) 3 6    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S TAB L E 1.11  MoSSaiC framework (continued) CHAPTER COVERAGE OUTPUT 1. Gain familiarity of different landslide types and how to identify those which may MCU and task teams be addressed by MoSSaiC understand the types of • Review landslide process introductory material in this book and other sources landslide risk for which MoSSaiC is applicable 2. Gain familiarity with slope processes and slope stability variables MCU and task teams 3. Understand- • Review landslide process variables as introduced in this book can identify different ing Landslide levels of landslide Hazard hazard and underlying physical causes 3. Gain familiarity with methods for analyzing slope stability MCU and task teams • Review slope stability software as introduced in this book and other sources can provide scientific rationale for landslide mitigation measures 1. Define the community selection process Agreed-upon selection • Identify available experts in government method and criteria, roles and responsibili- • Determine availability of software and data ties, timeline • Request permission to use data if necessary • Design appropriate method for selecting communities 2. Assess landslide hazard List or map of relative • Data acquisition: topography, soils, geology, land use, past landslides landslide susceptibility of different areas • Data analysis: landslide susceptibility or hazard within the study area 3. Assess exposure and vulnerability List or map of relative • Data acquisition: community locations, building footprints, housing/population vulnerability of density, census data or poverty data exposed communities • Data analysis: vulnerability of exposed communities to landslide impacts in 4. Selecting terms of physical damage, poverty, or other criteria Communities 4. Assess landslide risk List or map plus list of • Data analysis: landslide susceptibility/hazard, exposure, and vulnerability data most-at-risk communi- combined to determine overall landslide risk for study area ties for possible risk reduction measures • Data analysis: identify communities exposed to highest levels of landslide risk 5. Select communities Prioritized community • Conduct brief site visits of short-listed communities to confirm results short list • Consult community liaison task team and other relevant local stakeholders to review list • Confirm prioritized community short list according to selection criteria 6. Prepare site map information for selected communities Hard-copy map and • Data acquisition: most detailed maps and aerial photos of selected communities aerial photo for use on site • Map preparation: assemble community maps/photos and print hard copies 1. Identify the best form of community participation and mobilization MCU agrees on 5. Community- • Review and determine the most suitable form of community participation appropriate community Based participation strategy • Identify available community liaison experts in government Mapping for Landslide 2. Include key community members in the project team Key community Hazard • Identify existing or new community representatives members included Assessment • Hold initial discussions with community representatives to brief them on mapping and project rationale (continued) CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   37 TAB L E 1.11  MoSSaiC framework (continued) CHAPTER COVERAGE OUTPUT 3. Plan and hold a community meeting First community • Take advice from government and community representatives on location and meeting held style of meeting • Compile a community base map from existing maps, plans, and aerial photos (see section 4.7) to bring to the meeting 4. Conduct the community-based mapping exercise; this will entail a considerable Community slope amount of time in the community feature map • Talk with residents in each house to begin the process of engagement, knowledge sharing, and project ownership • Observe and discuss wide-scale and localized slope features and landslide hazard • Add local knowledge and slope feature information to the base map 5. Community- Based 5. Qualitatively assess the landslide hazard and potential causes Slope process zone Mapping for • Use the community slope feature map to identify zones with different slope map (relative landslide Landslide processes and landslide hazard hazard) Hazard • Evaluate the role of surface water infiltration in contributing to the landslide hazard Assessment 6. Quantitatively assess the landslide hazard and the effectiveness of surface water Determination of management to reduce the hazard viability of MoSSaiC • Use physically based software or simpler means to assess the likely contribution of approach surface water to landslide hazard • Assess whether reducing surface water is likely to reduce landslide hazard 7. Identify possible locations for drains Initial drainage plan and • For each slope process zone, determine the most appropriate surface water prioritization matrix management approach • Prioritize the zones according to relative landslide hazard 8. Sign off on the initial drainage plan: organize a combined MCU-community Initial drainage plan walk-through and meeting to agree on the initial drainage plan sign-off 1. Identify the location and alignment of drains Proposed drainage plan • Use the slope process zone map and initial drainage plan as a starting point; apply (drain alignments and drainage alignment principles to identify potential drain network alignment dimensions) • Refine alignment details on site 2. Estimate drain discharge and dimensions • Calculate surface water runoff and household water discharge into proposed drains • Calculate required drain size 3. Specify drain construction and design details Full drain specification 6. Design and 4. Incorporate houses into the drainage plan List of quantities Good Practice • Identify houses to receive roof guttering, gray water pipes, water tanks, and needed for household for Slope hurricane straps connections Drainage • Determine how household water will be directed to the drains (via pipes con- nected by concrete chambers or small drains) 5. Produce final drainage plan Final drainage plan and • Include all drain alignment and household connection details on the plan cost estimate • Estimate total project cost from unit costs 6. Stakeholder agreement on plan Sign-off on the final • Meet with the community and refine the plan drainage plan • Complete checks regarding relevant safeguards • Submit plan for formal approval (continued) 3 8    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S TAB L E 1.11  MoSSaiC framework (continued) CHAPTER COVERAGE OUTPUT 1. Prepare work package and request for tender documentation Work packages for • Prepare a bill of quantities for the planned works implementation of drainage intervention • Incorporate appropriate contingency and any double-handling costs (i.e., where to reduce landslide material has to be delivered to sites where access is difficult and requires the hazard establishment of a storage site between delivery and construction site locations) • Decide on work package size that maximizes community engagement and meets procurement requirements • Prepare design drawings and plans to accompany each work package • Identify an appropriate plan for procuring materials depending on the community contracting approach, community capacity, and project procurement requirements 2. Conduct the agreed-upon community contracting tendering process Briefing meeting for • Identify potential contractors from the community and provide briefing on proposed contractors held; works and work packages, emphasizing the need for good construction practice community contracts 7. Implement- awarded ing the • Invite tenders from contractors, providing assistance or training on how to submit Planned a tender document Works • Evaluate tenders, award contracts, and brief contractors on safeguards 3. Implement construction Briefing meeting for • Select experienced site supervisors community held; construction under • Authorize start of construction and meet with the community to discuss the way construction process and introduce site supervisors • Closely supervise the works to ensure good construction practices; clear commu- nication among contractors, supervisors, community, and the MoSSaiC core unit; and timely disbursement of funds for procurement of materials and payment of contractors/laborers 4. Sign off on completed construction Construction • Identify outstanding works completed and signed off on • Arrange for any necessary repairs or minor modifications • Sign off on completed construction and pay withholding payments to contractors 1. Understand how new practices are adopted Assessment of aspects • Use the steps in the ladder of adoption and behavioral change model to identify of behavioral change communication and capacity-building needs in each community and in govern- to be addressed by ment communication and capacity-building • Understand stakeholder perceptions and the role of community participation activities 2. Design a communication strategy Communication • Review existing resources and methodologies for designing a communication strategy strategy 8. Encouraging • Identify communication purposes and audiences Behavioral • Select forms of communication and design messages Change 3. Design a capacity-building strategy Capacity-building • Review knowledge into action approaches strategy • Identify levels of capacity, capacity requirements, and activities for building capacity 4. Plan for postproject maintenance Project maintenance • Understand the need for incorporating maintenance into drain design and project options planning 5. Map out the complete behavioral change strategy Map of capacity- • Map the agreed-upon behavioral change strategies and associated actions building strategies (continued) CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 9 TAB L E 1.11 MoSSaiC (continued) CHAPTER COVERAGE OUTPUT 1. Agree on key performance indicators (KPIs) for immediate project outputs List of project output • Develop and agree on a list of KPIs that comply with donor/government needs KPIs for evaluation and MoSSaiC output measures 2. Agree on KPIs for medium-term project outcomes List of project 9. Project • Develop and agree on a list of project outcome measures that allow evaluation of outcome KPIs for Evaluation landslide hazard reduction, project costs, and behavioral change evaluation 3. Undertake project evaluation Project evaluation • Agree on responsibilities for short- and medium-term data collection and the report project evaluation process • Carry out the evaluation Countries with small and vulnerable econo- disasters with respect to their capital stock mies, such as many SIDS and land-locked are all SIDS and LLDCs, such as Samoa and developing countries (LLDCs), have seen St. Lucia (UN 2009, 9). their economic development set back decades by disaster impacts. The countries Figure 1.24 shows the impact Hurricane with the highest ratio of economic losses in Allen (1980) had on the economy of St. Lucia. TA BLE 1 .1 2  Characteristics of MoSSaiC project locations in the Eastern Caribbean, 2004–10 FACTOR DESCRIPTION Region Eastern Caribbean—SIDS with high vulnerability to natural disasters (UNISDR 2009) Countries St. Lucia, Dominica, and St. Vincent and the Grenadines Slopes Slopes of 25–50 degrees, which had previously exhibited instability at low rainfall intensities (typically as low as 1 in 1 year 24-hour events) Slope material Often comprising deep residual soils over highly weathered volcanic bedrocks or conglomerates Communities Unauthorized urban communities—unregulated development, densely built, with poor construction quality; each community typically comprising 20–100+ houses Risk drivers Rainfall events triggering landslides on slopes with increased susceptibility to landslides due to natural and anthropogenic influences FI G U R E 1.22  Typical communities and risk drivers for MoSSaiC interventions a. Hillsides prone to landslides and b. Housing stock typical of vulnerable c. Density of unauthorized housing populated by unauthorized housing. communities. increases likelihood of property loss. 4 0    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S FI G U R E 1.2 3  Countries with damages from disasters exceeding 1 percent of GDP share of GDP (%) 10 8 6 4 2 0 St. Lucia Grenada St. Kitts & Nevis Samoa Nicaragua Maldives Mongolia Vanuatu Yemen, Rep. Dominica Virgin Islands Guyana Burkina Faso Tonga Belize Madagascar Jamaica El Salvador Bahamas Bangladesh Zimbabwe Fiji Bolivia Mauritius Nepal Source: World Bank 2010b. FI G U R E 1.24  Impact of Hurricane Allen illustrated by figure 1.25, which shows a com- (1980) on the economy of St. Lucia munity in Dumsi Pakha, a small village located in the Darjeeling Hills, in the Lesser Himalaya. constant 2000 $, millions It is a hillside with high-density housing and 3,000 no provision for surface water management. 2,500 without e ect With an average elevation of 2,050 m, the area of disasters 2,000 has steep slopes and loose topsoil, giving rise to 1,500 frequent landslides over recent years. In spite with e ect of disasters of strict rules and regulations, homes continue 1,000 to be constructed in the area (Savethehills 500 2011). This environment is thus very similar to 0 those of the Eastern Caribbean. –500 –1,000 1970 1980 1990 2000 F IGUR E 1. 2 5  MoSSaiC is applicable to Source: UNISDR 2009. many locations outside the Eastern Caribbean The dark brown line shows the actual cumula- tive net capital formation for 1970–2006; the light brown line shows the projected cumula- tive net formation without economic losses from disasters. The main MoSSaiC principles and methods developed in the Eastern Caribbean context are applicable in other parts of the humid trop- ics with comparable landslide risk drivers. The Source: Praful Rao, Savethehills, Kalimpong, India. potential breadth of MoSSaiC applicability is CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    4 1 1.5 STARTING A MOSSAIC Thus far, MoSSaiC has been applied at the INTERVENTION small scale (section 1.4.6), using the definitions of Binswanger-Mkhize, de Regt, and Spector (2009) shown in table 1.13. MoSSaiC may Starting a MoSSaiC intervention requires iden- potentially be scaled up to national and tification of the scale and scope of the project, regional levels, while retaining community- creation of teams to deliver the program, selec- scale effectiveness and innovation. Several tion of communities in which interventions are potential issues need to be recognized when to be made, generation of a project logframe, considering such scale-up (table  1.14), and and understanding of the issues involved in Easterly’s “test” should be taken into account: making the project sustainable. This book is designed to provide a flexible The sad part is that the poor have had so little blueprint for establishing a MoSSaiC interven- power to hold agencies accountable that the tion. While the majority of the text is, of neces- aid agencies have not had enough incentive sity, devoted to the details of delivering on- to find out what works and what the poor the-ground mitigation measures, equal weight actually want. The most important sugges- should be given by the MCU to evidence of tion is to search for small improvements, performance of the measures (physical and then brutally scrutinize and test whether the cost-effectiveness, introduced in section 1.4.4), poor get what they wanted and were better and to the longer-term outcomes and behav- off and then repeat the process (Easterly ioral change achieved as a result (table 1.9 and 2006, 180). figure 1.21). 1.5.2 Define the project teams and 1.5.1 Define the project scale stakeholders Initiating a new form of community-based Three types of team project can rarely be done in one fell swoop at the national level; the numbers are just too To build the necessary teams involves iden- daunting (table 1.13). Rather, starting with a tifying colleagues from all relevant stake- few pilot projects should result in a locally rel- holder groups with a keen interest in pro- evant set of logistics, operational and training moting MoSSaiC and who have the requisite books, materials, and tools that can then be expertise. Three types of team need to be used to support a wider program. built: TA BLE 1 .1 3  Magnitudes of scale-up SMALL-SCALE LCDD PILOT PHASE OF SUCCESS SCALE-UP SCALED UP 1 district/administrative 1–4 districts/administrative All districts/administrative center centers centers 1–4 subdistricts 6–24 subdistricts All subdistricts 5–20 community groups  100–1,000 community groups  Tens of thousands–hundreds of thousands of community groups < 50 community projects 100–2,000 projects Hundreds of thousands of projects < 50,000 people 100,000–1 million people Many million people Source: Binswanger-Mkhize, de Regt, and Spector 2009. Note: LCDD = local- and community-driven development. 42    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S TAB L E 1.14  Issues to consider when scaling up MoSSaiC ISSUE COMMENT “Sometimes things work for idiosyncratic reasons—a charismatic (and literally Replication may irreplaceable) leader or a particular (and unrepeatable) crisis that solidifies support not be possible for a politically difficult innovation. So one-time successes may not be replicable” (World Bank 2004, 108). While certain elements of the approach may provide sound guidance, there are Experimentation limits to the standardization of any approach. “Experimentation, with real learning may be necessary from the experiments, is the only way to match appropriate policies with each country’s circumstances” (World Bank 2004, 108). A social franchise model is recognized as a possible suitable scaling-up approach in which a close dialogue is maintained between countries undertaking the approach Adopting a (franchisee) and the originators (franchisors). This aims to capture the advantage of recognized standardization and experimentation referred to above. To that end, the franchisees approach to (whose role is to implement the approach locally) are decentralized and largely scale-up may give autonomous. “A pilot project that is developed by the franchisor is replicated by a value added number of franchisees subject to defined guidelines. These are usually laid down in the form of a book and communicated to the franchisees through training offered by the franchisor” (Ahlert et al. 2008, 23). • MoSSaiC core unit. This typically com- leaders. Community leaders can play a cata- prises local government agency expert lytic part in projects: conveying the vision practitioners and project managers in the to other residents and coordinating with fields of civil engineering, social develop- government teams. In some cases, an indi- ment and community outreach, emergency vidual with particular skills and an under- management, financial management, water standing of the project’s technical aspects resource management, and agriculture. The can act as a catalyst and raise awareness of MCU acts as the bridge between regional slope management issues in his or her own and national initiatives for risk reduction, and other communities. Such understand- the government technical and field task ing establishes appropriate consultative teams, and the communities. To be effective channels at the start of the intervention, in its role, the MCU must have an under- and ensures that expectations are appropri- standing of the relational nature of the ately set in terms of outcomes and likely community—its key players, leaders, beneficiaries. groups, and elected representatives; and its relationships with government, especially The teams, together with their roles and in terms of previous social intervention responsibilities, are fully defined in chapter 2. activities. Teams require an organizational structure • Government task teams. Teams will to both manage a process and deliver outputs include a number of groups of specialists and outcomes. Structuring an MCU, and cap- and practitioners such as GIS technicians, turing existing government and community field survey technicians, community liaison individuals within country, is a deliberate officers, local engineers, and planning offi- attempt to recognize that cers. The leaders of the various government …a Bureaucracy works best where there is task teams are likely to be MCU members. high feedback from beneficiaries, high incen- tives for the bureaucracy to respond to such • Community task teams. The three main feedback, easily observable outcomes, high constituents from the community will be probability that bureaucratic effort will residents, contractors, and community translate into favourable outcomes, and com- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   43 petitive pressure from other bureaucracies • Analyzing—identifying the strengths and and agencies (Easterly 2002, 4). weaknesses of existing policies and service and support systems Stakeholder involvement • Setting objectives—deciding and articulat- MoSSaiC requires a broad and cohesive stake- ing what is needed holder base, and one that deliberately encour- ages community participation. The MCU • Creating strategy—deciding, in pragmatic should identify all potential stakeholder terms, directions, priorities, and institu- groups and shape the management structure tional responsibilities according to the local context. Table 1.15 indi- • Formulating tactics—developing or over- cates the likely stakeholders and their respec- seeing the development of project policies, tive involvement. specifications, blueprints, budgets, and Given the community basis of MoSSaiC, it technologies needed to move from the pres- is important for the MCU to ent to the future • be clear on the purpose of participation, • Monitoring—conducting social assess- • know the value offered by community ments or other forms of monitoring of proj- engagement, ect expenditures and outputs • understand how the community can par- Community selection ticipate, and Communities can be prioritized and selected • anticipate any unintended consequences of by addressing the following questions using participation. available data: • Which communities have suspected land- Participation allows stakeholders to collab- slide problems? oratively carry out a number of activities in the program cycle, including the following (World • Are these communities vulnerable in pov- Bank 1998): erty terms? TAB L E 1.15  Likely stakeholders and their potential involvement in a MoSSaiC intervention STAKEHOLDER INVOLVEMENT Householders • May be directly at risk from landslides and/or contribute to the hazard due to adverse slope management practices • May have important knowledge of localized slope processes and slope history • May have skills in drain construction Landowners Will need to be consulted if drainage structures are to be built and access rights required Community representatives May represent a community project committee and become advocates for the project Government agency May have a formal role in project initiation and implementation representatives Residents of other potential May perceive that their needs are greater or have skills or experiences to share communities NGOs or similar agencies May be coordinating with the same government and community representatives on a working in the same community different, but potentially related, project Donors May have instigated the approach but whose representatives may be seen as remote partners Elected parliamentary represen- May have lobbied in the community selection process and subsequently become advocates tatives for the approach Media representatives Will cover project roll-out and can choose how they portray the delivery, purpose, and impact 4 4    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S • Can the landslide hazard be confirmed? 1.5.4 Establish a project logframe • Is the intervention likely to be cost-effec- Establishing a project framework at inception tive, and does it fit the project scope? is an important starting point for the MCU in Typically, there will be a range of data and preparing the overall project design. A log- political factors that need to be assimilated by frame is a widely used document that provides the MCU in prioritizing and selecting commu- such a structure; it is essentially a project nities. Chapter 4 details a process that can be design checklist, and is a recognized frame- used for community selection. work among donor agency and government stakeholders. The MCU should create a 1.5.3 Adhere to safeguard policies MoSSaiC logframe at the start of the project Implementation of risk reduction itself carries and refer to it throughout. potential risks. Safeguard policies seek to pre- The logframe analysis can be used as an itera- vent and mitigate undue harm to people and tive, dynamic tool throughout the project their environment by providing guidelines for cycle, rather than as a one-off exercise. It can the identification, preparation, and implemen- be used for identifying and assessing activi- tation of programs and projects. The effective- ties, preparing the project design, appraising project designs, implementing approved ness and development impact of DRR projects projects and monitoring, reviewing and eval- can be substantially increased as a result of uating project progress and performance attention to such policies. These policies have (AusAID 2000). In the words of DFID often provided a platform for the participation (c. 2003, 3), “it is a living document: it should of stakeholders in project design and have be reviewed regularly during approach and been an important instrument for building project implementation” (Benson and Twigg 2004, 87). ownership among local populations. Once teams are in place, stakeholders iden- The best logframes are designed with stake- tified, and a project logframe developed (sec- holder involvement to ensure that everyone tion  1.5.4), safeguard policies should be concerned understands the relationship sourced, developed, and adapted as necessary between inputs and the desired outputs, out- for the local context; they should then be comes, and impact. Both direct beneficiaries agreed upon and disseminated. While all those (primary stakeholders) and project partners involved in a MoSSaiC intervention should be (secondary stakeholders) should be involved aware of safeguard policies, they are of special in formulation of the project logframe. relevance to the MCU (in its managerial role; The logframe should be simple and concise see section 2.3.2) and to those involved in con- with the project goal, purpose, and outputs struction (see section 7.7.1). specified in full and anticipated activities sum- Practices for safeguards will vary depend- marized. It should be a stand-alone document ing on the country, donor agency, and govern- explaining the intentions of the project com- ment context. A useful starting point is the prehensively and at a glance, and should be no Safeguard Policies of the World Bank (2011). more than four pages long. Table 1.17 details a The MCU must ensure that the project com- sample project logframe, presented in the plies with any relevant safeguards and proto- form of a matrix. cols stipulated by a donor or the government, In this book, the detailed steps and outputs or dictated by good practice, although it is rec- identified in section 1.4.5 (and replicated at ognized that formal responsibility for compli- the beginning of each chapter) will be helpful ance may well lie elsewhere. Table 1.16 illus- in creating a logframe. Chapter 9 identifies trates some typical safeguards that might typical key performance indicators, overall apply. This list should not be viewed as com- project outputs, and longer-term outcomes prehensive and is not intended as a substitute that might be included in a MoSSaiC project for binding policies and procedures. logframe. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    4 5 TA BLE 1 .1 6  Typical safeguard policy considerations SAFEGUARD DESCRIPTION Evaluates a project’s potential environmental risks and impacts in its area of influence; examines project alternatives; identifies ways of improving project Environmental selection, siting, planning, design, and implementation by preventing, minimizing, assessment mitigating, or compensating for adverse environmental impacts and enhancing positive impacts; and includes the process of mitigating and managing adverse environmental impacts throughout project implementation. Is there the potential to cause significant conversion (loss) or degradation of natural habitats? It must be expected that donors would not support projects that would lead to the significant loss or degradation of any critical natural habitats, i.e., natural habitats that are • legally protected, • officially proposed for protection, or Natural habitats • unprotected but of known high conservation value. In other (noncritical) natural habitats, projects might be allowed to cause significant loss or degradation only when • there are no feasible alternatives to achieve the project’s substantial overall net benefits; and • acceptable mitigation measures, such as compensatory protected areas, are included in the project. Is the project situated in a disputed area? Has landownership been established and permission granted in writing if required? Projects in disputed areas may affect the relations between a wide range of stakeholders and claimants to the disputed area. Therefore, it is likely that donors Disputed areas and governments would only finance projects in disputed areas when there is no objection from the other claimant to the disputed area. It is possible that special circumstances of the case support financing, notwithstand- ing the objection. In this case it is to be expected that a transparent policy details the precise nature of such special circumstances. Involuntary resettlement can be defined not only as physical relocation, but any loss of land or other assets resulting in (1) relocation or loss of shelter; (2) loss of assets or access to assets; (3) loss of income sources or means of livelihood, whether or not the affected people must move to another location. Involuntary resettlement is triggered in situations involving involuntary taking of land and involuntary restrictions of access to legally designated parks and protected areas. A safeguard policy would aim to avoid involuntary resettlement to the extent Involuntary feasible, or to minimize and mitigate its adverse social and economic impacts. resettlement • A safeguard policy would promote participation of displaced people in resettle- ment planning and implementation, and its key economic objective would be to assist displaced persons in their efforts to improve or at least restore their incomes and standards of living after displacement. • A safeguard policy would prescribe compensation and other resettlement measures to achieve its objectives and require that borrowers prepare adequate resettlement planning instruments prior to donor appraisal of proposed projects. Cultural resources are important as sources of valuable historical and scientific Physical cultural information, as assets for economic and social development, and as integral parts of resources a people’s cultural identity and practices. The loss of such resources is irreversible, but fortunately, it is often avoidable. Source: World Bank 2011. 4 6    C H A P T E R 1 .   F O U N DAT I O N S : R E D U C I N G L A N D S L I D E R I S K I N CO M M U N I T I E S TAB L E 1.17  Example of a logframe format IMPORTANT RISKS AND PROJECT SUMMARY MEASURABLE INDICATOR MEANS OF VERIFICATION ASSUMPTIONS GOAL: Higher-level goal to which What external conditions are the project will contribute (such as essential for the project to Millennium Development Goals, make its expected contribu- poverty reduction). Note that the tion to the goal goal is not intended to be achieved through the project alone. PURPOSE: What will be achieved? The quantitative measures Sources of information Risks and external conditions Consider what will change, who will or qualitative evidence by that will be used to assess on which the success of the benefit and how, and the impact the which achievement of the the indicator(s). These project depends project will have in relation to the purpose will be judged; should be numbered to aims. This should be one statement. these should be numbered. correspond with indicator numbering. OUTPUTS: Identify the set of SMART (specific, measur- Sources of information to Risks—factors not within the realistic measurable outputs able, achievable, relevant, be used to identify control of the project that (outcomes/results) that will be and time-bound) indicators whether the indicators may restrict the achievement needed to work together to ensure must be included for each have been met. These of the outputs or of the the achievement of the purpose. output. Preparing useful should be numbered to purpose, even if all the (Outputs are not simply completed and time-bound indicators correspond with indicator outputs were achieved activities—if training is the activity, is an essential element for numbering. then a completed training session is effective monitoring and simply a completed activity; reporting. These should be behavioral change as a result of numbered to correspond receiving the training would be an to output numbering. output.) Normally, projects have four or five outputs. These should be numbered. ACTIVITIES: These are the tasks to A summary of the project budget and other key inputs and resources to complete the be completed to produce the activities outputs. They should be given numbered to correspond to the relevant output. Source: DFID n.d. 1.5.5 Brief key leaders of people to champion the approach. This is Readers should use the information in this the starting point for chapter 2. chapter to initiate discussions and brief strate- gically placed policy makers, senior project MILESTONE 1: managers, and local experts. Effective commu- nication of the MoSSaiC vision and founda- Key catalytic staff briefed on tions will help establish potential membership MoSSaiC methodology of the MCU, and thus help secure the support CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   47 1.6 RESOURCES 1.6.1 Who does what CHAPTER TEAM RESPONSIBILITY ACTIONS AND HELPFUL HINTS SECTION Policy/decision • Become familiar with ex ante DRR approach 1.3 makers, funding Understand DRM Helpful hint: Be aware of recent influences on DRM policy agency (section 1.3.3). • Become familiar with MoSSaiC approach 1.4 Understand MoSSaiC Helpful hint: Be aware of unique aspects of MoSSaiC (section 1.2.1). • Identify government departments, agencies and other 1.5.2 Understand local institutional organizations that could contribute to community-based DRM context landslide risk reduction Identify individuals who have the • Brief key individuals on MoSSaiC 1.5.5 potential to contribute to MoSSaiC MCU • Become familiar with MoSSaiC approach 1.3; 1.4 Upon appointment, understand DRM and the MoSSaiC approach Helpful hint: Be aware of unique aspects of MoSSaiC (section 1.2.1). Government task • Become familiar with MoSSaiC approach 1.3; 1.4 teams Upon appointment, understand DRM and the MoSSaiC approach Helpful hint: Be aware of unique aspects of MoSSaiC (section 1.2.1). When community task teams • Communicate the MoSSaiC vision to community task 1.4 have been appointed, inform the teams team members of MoSSaiC Community task • Become familiar with MoSSaiC approach 1.3; 1.4 teams Upon appointment, understand DRM and the MoSSaiC approach Helpful hint: Be aware of unique aspects of MoSSaiC (section 1.2.1). 1.6.2 Chapter checklist SIGN- CHAPTER CHECK THAT: TEAM PERSON OFF SECTION 99Existing local landslide risk reduction activities identified 1.3 99MoSSaiC approach understood 1.2.1; 1.4 99Relevant stakeholder groups and individuals identified and briefed 1.5.2 99All necessary safeguards complied with 1.5.3 99Milestone 1: Key catalytic staff briefed on MoSSaiC methodology 1.5.5 1.6.3 References Ahlert, D., M. Ahlert, H. V. D. Dinh, H. Fleisch, T. Heußler, L. 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Maskrey, “Defining the Community’s Role in Disaster Mitigation” (1992, 4) CHAPTER 2 Project Inception: Teams and Steps 2.1 KEY CHAPTER ELEMENTS 2.1.1 Coverage This chapter identifies existing within-coun- responsible for project implementation and try capacity to build the MoSSaiC (Manage- defines typical project steps. The listed groups ment of Slope Stability in Communities) teams should read the indicated chapter sections. AUDIENCE CHAPTER F M G C LEARNING SECTION    How to start the project with the MoSSaiC core unit: mission, members, 2.2, 2.3 roles, responsibilities    How to select the government task teams; their roles and responsibilities 2.4    How to select the community task teams; their roles and responsibilities 2.5    Main MoSSaiC project steps for each team 2.6, 2.7 F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors 2.1.2 Documents CHAPTER DOCUMENT TO BE PRODUCED SECTION Documents specifying team structures and personnel, and defining roles and responsibili- 2.6 ties, with sign-off by representatives from the relevant government agencies Project operations manual or equivalent specifying steps and associated milestones for 2.6, 2.7 implementation 55 2.1.3 Steps and outputs STEP OUTPUT 1. Establish the MoSSaiC core unit (MCU); define and agree on key responsibilities MCU formed • Identify available experts in government • Form the MCU and establish communication lines with government 2. Identify and establish government task teams; define and agree on key Government task responsibilities teams formed • MCU to identify individuals from relevant ministries to form government task teams (mapping, community liaison, engineering, technical support, communi- cations, advocacy) • Define roles and responsibilities of the teams 3. Identify and establish community task teams; define and agree on key responsi- Community task bilities* teams formed • MCU to identify individuals from selected communities to form community task teams (residents, representatives, construction teams) • Define roles and responsibilities of the teams 4. Agree on a general template for project steps Project steps • Review project step template and amend as necessary determined and responsibilities • Assign team responsibilities to relevant project steps; confirm project mile- assigned stones *This can only be done once communities have been selected for a MoSSaiC project; see chapters 4 and 5. 2.1.4 Community-based aspects coordination of a diverse team including community residents, field and mapping An important part of this chapter is the identi- technicians, engineers, contractors, and fication of the members of community-based social development officers. A strong, multi- task teams (community residents, representa- disciplinary MoSSaiC core unit (MCU) tives, contractors, and landowners), which are needs to configure and manage specific proj- an integral part of the wider MoSSaiC team. ect steps, roles, and responsibilities and Without the full recognition and involvement thereby attempt to reproduce the success of these teams, the project would have no factors outlined in table 2.1. grounding in the communities, the commu- nity-based mapping process and landslide The role of the MoSSaiC core unit hazard assessment would be incomplete (or incorrect), and there would be no sustainable A central element of MoSSaiC is the develop- delivery mechanism for appropriate landslide ment of a cross-ministry team of government hazard reduction measures. managers and expert practitioners. This book refers to this team as the MCU; different coun- tries may chose to give the team another name. 2.2 GETTING STARTED The MCU will perform the following: • Identify clear project steps that will effec- 2.2.1 Briefing note tively deliver on-the-ground landslide haz- An integrated approach to landslide risk ard reduction measures in communities in management the form of surface water drainage To deliver landslide risk reduction measures • Identify and draw on local expertise to in vulnerable communities requires the implement project steps by establishing 5 6    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S TAB L E 2 .1  Key characteristics of highly successful social development projects CHARACTERISTIC Quality participation from all stakeholders Participants given responsibility for structuring their project involvement Participants, especially beneficiaries, involved in project design Project team composition and team continuity Integrated attention to social development themes affecting project implementation Analysis of socially relevant aspects of the project Source: IEG 2005. appropriate task teams at the government • Project steps and milestones should be and community levels agreed upon. • Ensure that government and donor proto- 2.2.3 Risks and challenges cols are followed at every step Appropriate objectives • Ensure that appropriate landslide assess- The concepts contained in this book should be ment, community selection and engage- adapted by each country to reflect the local ment, and contracting procedures are fol- risk profile and government and community lowed contexts. In particular, objectives should not • Clearly communicate task team roles and be either overly ambitious or open-ended responsibilities so each individual under- since this can weaken accountability, prevent stands his or her specific tasks and contri- the delivery of appropriate mitigation mea- bution within the wider project sures, and reduce the likelihood of adoption of good slope management practices by govern- • Develop and convey the vision (and poten- ment and communities alike. tial) for reducing landslide risk in vulnera- ble communities in a way that is relevant to Taking time to identify MCU membership the teams and wider audiences. The cross-disciplinary MCU is the core mana- gerial structure of MoSSaiC. Identifying indi- The breadth of activities involved in viduals within government and related agen- MoSSaiC demands that roles and responsibili- cies who are committed to the concept of ties be very clearly identified and agreed upon. formulating a community-based approach to This chapter is designed so the MCU can be landslide risk reduction is the starting point for built and equipped to complement existing any MoSSaiC project. Sufficient time should be government structures. spent talking to a broad range of interested par- ties and individuals to identify MCU team 2.2.2 Guiding principles members who share the MoSSaiC vision and The following guiding principles apply in have relevant positions, skills, or expertise. starting up the MoSSaiC project: Avoiding parallel structures • An MCU should comprise a membership The establishment of the MCU and its associ- that is approved of and respected by gov- ated task teams should not create parallel ernment and within communities. structures that compete with or undermine • Clear, widely known responsibilities should existing institutional structures or democrati- be established for the MCU and each cally elected local or national governments MoSSaiC task team. (Mansuri and Rao 2003). CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    5 7 Fully developing and engaging with all task teams • Inadequate attention to project safeguards Task teams should be identified and appropri- (especially if there are issues of landowner- ately staffed for each project step to ensure that ship relevant to any proposed construction no individual or group is overburdened or or required access) required to take on tasks exceeding expertise. Relevance of project documents Clear, consistent, and frequent communica- tion will maintain momentum and commit- Avoid producing documents that are unlikely ment from individuals who may have other to be used and read. Instead, focus on develop- responsibilities. The form this communication ing a suite of documents that provide sound takes needs to be agreed upon at the start of records for subsequent project impact analy- the project. Whether regular communication sis, enable teams to undertake their tasks, and is by e-mail or briefing meetings, for example, serve public awareness and media initiatives. will very much depend on local practices. Creating a platform for behavioral change Realistic project time frames Urban development can generate landslide risk; conversely, landslide risk can affect devel- Project initiators are frequently overly opti- opment. At a community level, each household mistic about the schedule for implementing can inadvertently contribute to landslide risk multidisciplinary projects (see, e.g., IEG or, with good slope management practices, 2000). Because MoSSaiC integrates govern- play an important role in its mitigation. Gov- ment and community, and focuses on delivery ernment projects and policies can also either of physical landslide reduction measures in increase or reduce landslide risk at the com- communities, it is particularly important that munity, municipal, or national scale. Creating expectations of project timing and outcomes a platform for behavioral change in communi- are set realistically. This is not just to avoid ties and governments is an important part of unrealized expectations and having to deal the MoSSaiC vision, and it is best achieved by with the consequences (particularly in com- engaging with the community from start to munities), but for the more positive reason finish and by using existing government staff that being seen to deliver the project on time to form the MCU. In this way, landslide hazard and on budget is likely to encourage behavioral reduction measures can be delivered on the change. Small successes build confidence and ground, and behavioral changes be achieved as lead to wider uptake. the community and government teams learn by doing. Quality of project management A lack good quality project management can 2.2.4 Adapting the chapter blueprint to lead to a variety of poor outcomes: existing capacity This chapter provides a flexible blueprint for • Inadequate project conceptualization and MoSSaiC project inception. Funders and pol- design (potentially resulting in loss of finan- icy makers, in conjunction with the MCU, cial or decision-making transparency, poor should adapt this blueprint to suit local capac- scientific justification of hazard reduction ity and institutional structures. measures, and inadequate design or con- Use the matrix opposite to determine exist- struction of hazard reduction measures) ing capacity to configure multidisciplinary • Poor quality construction (if site supervision community-based projects, and hence the is not scheduled sufficiently frequently) likely capacity for forming MoSSaiC teams. • Project interruptions and contractors not 1. Assign a capacity score from 1 to 3 (low to getting paid on time (if the funding stream high) to reflect existing capacity for each is not adequately managed) element in the matrix’s left-hand column. 5 8    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S EXISTING CAPACITY CAPACITY ELEMENT 1 = LOW 2 = MODERATE 3 = HIGH Community organization and Communities generally lack Some community organiza- Functioning community-based representation by leaders structures and leadership tional or leadership structures organizations and leadership Government-community Role nonexistent Government-community Well-developed government- liaison role liaison on informal/unstruc- community liaison role tured basis Previous community-based Little history of community- Some previous community- Good track record of projects based projects based projects, but outcomes delivering successful commu- not sustained nity-based projects Government experience in Little or no experience in Some community-based One or more agencies with implementing community- implementing community- works implemented by one or proven experience in imple- based works (construction) based works more government agencies menting community-based works with a range of donor/ government funding models Government experience in Little or no experience in Some community-based Experience in community- implementing community- implementing community- disaster risk management based disaster risk manage- based disaster risk manage- based disaster risk manage- projects, with main focus on ment projects, including ment projects ment disaster preparedness or hazard assessment and vulnerability reduction mitigation Coordination of multidisci- Community-based projects Some cross-ministry coordina- Well-integrated structures plinary community-based undertaken by a single tion on a project-by-project across government to projects implementing agency basis facilitate cross-ministry coordination Project safeguards Documented safeguards need Documents exist for some Documented safeguards to be located; no previous safeguards available from all relevant experience in interpreting and agencies operating safeguard policies CAPACITY LEVEL HOW TO ADAPT THE BLUEPRINT 1: Use this chapter The country needs to strengthen its capacity in order to initiate a MoSSaiC project and form the required in depth and as a teams. This might involve the following: catalyst to secure • Actively searching for a policy entrepreneur to start the process by which an MCU is formed support from other agencies as • Organizing cross-agency and cross-government department meetings to explain the MoSSaiC vision and appropriate the need to create an MCU 2: Some elements The country has strength in some areas, but not all. Elements that are perceived to be Level 1 need to be of this chapter will addressed as above. Elements that are Level 2 will need to be strengthened, such as the following: reflect current • If the government has experience in hazard mitigation using multidisciplinary teams but not at the practice; read the community level, it should identify agencies already working in communities that could be partners in a remaining elements MoSSaiC project. in depth and use them to further strengthen capacity 3: Use this chapter The country is likely to be able to form an MCU based on existing proven capacity. The following would as a checklist nonetheless be good practice: • Document relevant government experience in community-based hazard mitigation, project manage- ment, and related safeguards CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    5 9 2. Identify the most common capacity score risk reduction options, and then treatment of as an indicator of the overall capacity level. the risk. This requires the coordination of experts in the areas (and order) shown in 3. Adapt the blueprint in this chapter in accor- table 2.2. dance with the overall capacity level (see guide at the bottom of the previous page). A new way of building capacity A review of selected capacity assessment Forming the MCU from existing staff within methodologies can be found in UNDP (2006), governments and agencies is a sound way of and Venture Philanthropy Partners (2001, 84) seeking to build capacity within government. provides an example of a detailed capacity Initially, capacity is enhanced simply by pro- assessment framework for nonprofit organiza- viding the opportunity for government staff to tions. exercise their expertise in an innovative way and as part of a multidisciplinary team. This expertise is developed and increased through 2.3 ESTABLISHING THE MoSSaiC hands-on experience as the project progresses. CORE UNIT Successful implementation of landslide risk reduction measures in the first few communi- 2.3.1 Rationale ties encourages behavioral and policy changes within government. Integrated approach to a multidisciplinary The MCU thus becomes both a focus for problem building capacity and the means of building Typically, the management of landslide risk capacity in other teams, as it can provide the involves assessment of the risk, evaluation of following: TAB L E 2 .2  Typical landslide risk management project cycle TYPICAL PHASE REQUIRED SKILLS/EXPERTISE Landslide Identify the project: Determine the need for and interest in a risk landslide risk reduction project Management, financial, donor agency, management Formulate the project: Define the project scope, budget, aims, engineering/scientific project preparation objectives, and feasibility Identify the broad landslide risk: Identify the relative landslide Local community knowledge, mapping, susceptibility or hazard of different areas to different landslide types, data management, engineering/scientific and the relative vulnerability of the exposed communities Landslide Understand and estimate the specific landslide risk: For a specific risk community and hillside, identify the underlying landslide hazard Mapping, engineering/scientific, social assessment drivers and confirm the level of the hazard; confirm the relative science, economic exposure and vulnerability of the community Evaluate the risk: Compare with other risks and decide whether to accept or treat the risk Management, financial, engineering/ Identify disaster risk reduction options: Typical options are to avoid scientific or reduce the hazard, reduce vulnerability, or transfer the risk Plan the risk mitigation: Design the landslide hazard reduction Landslide Engineering/scientific measures (drainage to capture surface water and household water) risk reduction Implement risk mitigation: Issue and manage contracts and construc- Financial/contracting, community liaison, tion, raise public awareness engineering, supervision, construction Monitor and evaluate: Check project progress, problems, solutions, Management, community liaison, sustainability, impact engineering 6 0    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S • Project vision, in that it is distinctive and tially requires assistance, has the choice of designed to deliver physical outputs in helping or not helping. The aid recipient then communities has the choice of expending high or low effort in return. If the donor extends help and the • Task team coordination, to ensure that recipient contributes high effort, both donor appropriate within-government and gov- and recipient benefit significantly. However, ernment-community linkages are forged from the recipient’s perspective, it could be • Encouragement of capacity building and even better off by expending low effort increased resilience at the community level, (table 2.3). by engaging and involving communities Although the donor would prefer a situa- from the outset and in a transparent manner tion in which the recipient expended high effort, most cases result in a low effort (Ostrom • Focal point for collating and managing et al. 2001)—and consequent poor levels of information relating to landslides; such sustainability. Ostrom et al. (2001, 32) con- data are often dispersed across different clude that “it is the recipient whose actions ministries, agencies, and consultants make the difference in outcomes between sus- Sustaining good landslide management practice tainable and non-sustainable,” adding that a in-country more sophisticated donor would condition aid on participation by the recipient and make Certain projects may need high-level expertise efforts to give the recipient a sense of owner- to be brought into a country to supply special- ship. It is expressly these two features that ized engineering or scientific knowledge, usu- MoSSaiC seeks to capture through its team ally in terms of design but sometimes in site structure. investigation as well. Such external expert MCU and the policy entrepreneur role input should supplement rather than replace in-country project management and task Policy entrepreneurs “introduce, translate, teams. Focusing on a government-based MCU and help implement new ideas into public and local task teams is the best approach to practice” (Roberts and King 1991). Given the ensuring sustainable landslide risk manage- issues observed by Prater and Londell (2000) ment by and summarized in table 2.4, it is important to identify a policy entrepreneur to champion • creating a learning organization dynamic, MoSSaiC and support, or be part of, the MCU. • promoting cost-efficiency, MoSSaiC core unit mission • providing secure and sustainable govern- ment-community links, The MCU balances two elements that drive • providing for a coherent connection with and contribute to MoSSaiC project success: social development funds that can deliver projects at the community level, and TAB LE 2 . 3  The active Samaritan’s Dilemma • ensuring the optimal assimilation of appro- priate background data. RECIPIENT HIGH EFFORT LOW EFFORT Avoiding the “Samaritan’s dilemma” DONOR NO HELP 2,2 1,1 (SAMARITAN) HELP 4,3 3,4 A within-country MCU is a potentially sound way of avoiding the well-documented Samari- Source: Raschky and Schwindt 2009. Note: Subject preference (payoff) ranked from high (4) to low (1). The first tan’s dilemma. This problem, posed by number in each pair is the donor preference, the second is the recipient Buchanan (1977), revolves around the fact that preference. a donor, faced with a circumstance that poten- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   61 TA BLE 2 .4  Landslide risk reduction issues that need to be offset by a policy entrepreneur ISSUE ROLE OF POLICY ENTREPRENEUR Political agendas are unstable over time Help keep disaster risk reduction on the agenda by being versed in the technical aspects of risk reduction, be a political expert, and have strong personal commitment Prevailing view of landslide risk may be that there Can counter this view with evidence that landslide is nothing that can be done about it risk reduction can work and pay Hazard mitigation and socioeconomic develop- Understand and promote a scientific and socio- ment are complex issues; simplistic policies can economic framework for landslide hazard have unintended consequences, while complex mitigation policies policies are difficult to develop • Top-down drivers and processes—such as prised of existing government staff; the com- the social, economic, and political impera- munity task teams will include both unpaid tive to arrest landslide risk accumulation; volunteers (community leaders and residents) and the requirements of project manage- and paid contractors from within the commu- ment and financing nity. Cultural norms and a lack of incentives • Bottom-up drivers and processes—such may constrain effective management of task as the community imperative to reduce teams, and there will usually be limitations in landslide risk and improve livelihoods, the power of a single agency to influence community participation in project design, behavioral change among a broader govern- and engaging workers from the communi- ment base. The MCU should devise a commu- ties to implement the intervention nication and engagement strategy that com- bines formal government protocols with a 2.3.2 MCU roles and responsibilities culturally sensitive approach to achieve proj- ect acceptance, staff and team integration, and The responsibilities of the MCU are pre- consensual ownership (World Bank 2003). scribed by its five core missions (figure 2.1). MCU roles and responsibilities in this regard are as follows: 1. Establish project scope and teams • Be familiar with MoSSaiC aims and scope The first mission of the MCU is to establish the vision, scope, and cross-disciplinary basis • Define local project scope in terms of land- of the project, and to identify task teams in the slide risk management needs with respect government and the community. to the appropriate application of MoSSaiC The MoSSaiC methodology needs to be • Adapt the MoSSaiC blueprint for building understood and correctly applied if the goal of task teams and defining project steps, roles, reducing landslide risk in communities is to be and responsibilities achieved. Each chapter in this book relates to a different phase of MoSSaiC implementation. • Own and champion the vision, and lead and The MCU should be aware of what is involved encourage the task teams in each of these project phases (encapsulated in the “Getting started” section in each mod- • Develop an effective strategy to facilitate ule) so as to correctly configure the project the task teams in their roles and establish the task teams. 2. Stay community focused Forming the MCU within-country delivers cost-effective project management. The MCU From the outset, the MCU will need to focus and government task teams should be com- on delivering landslide risk reduction mea- 62    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S FI G U R E 2 .1  Five missions of the MoSSaiC core unit a. Mission 1: Establish the vision, scope, b. Mission 2: Ground the project in c. Mission 3: Ensure good design of and cross-disciplinary basis of the project communities throughout the process to landslide hazard reduction measures, and identify task teams in government create a platform for behavioral change and the quality and completion of and communities. in both government and communities. construction. d. Mission 4: Create a culture of good e. Mission 5: Identify project safeguard requirements (relating to issues such as the slope management practice, and evaluate potential for involuntary resettlement following slope failure and house destruction project impact and sustainability in or for resolving landownership for drainage lines). partnership with communities and funding agencies. of slopes to landslides and vulnerability of sures in vulnerable communities. This focus communities to the impact of landslides will require the development of strategies to engage the community from the start and to • Ensure that the selected communities are maintain that engagement during landslide consulted on their priorities and the poten- hazard mapping and assessment, through the tial for implementing landslide hazard design process, during implementation, and in reduction measures the follow-up phases. • Ensure that appropriate community par- The government task teams should be ticipation approaches are used in selecting encouraged to work with community mem- community task teams, mapping landslide bers both formally and informally in order to hazards and drainage issues, designing a benefit from community knowledge of local drainage intervention, and conducting liai- slope processes and relevant community social son with residents during and after the structures. The community thus becomes the project locus both of activities and of hands-on expe- rience for the government and community • Establish a realistic community contracting task teams. process by which contracting and procure- The MCU roles and responsibilities in this ment are undertaken on behalf of or by the regard are as follows: community • Develop a community selection process • Ensure that contractors from the commu- that is justifiable in terms of susceptibility nity are engaged and supervised in the con- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   63 struction of the landslide hazard reduction tices and the structures to enable them. The measures MCU is the core enabler in seeding project sustainability. • Encourage horizontal and vertical learning The MCU’s horizontal connection within through the hands-on involvement of task government, and its vertical integration with teams in the communities communities, provides the opportunity to 3. Maintain quality control develop a sustainable mechanism for embed- ding landslide risk reduction in practice and The effectiveness of any engineering or physi- policy. Building a team of senior civil servants cal measures constructed to reduce landslide and technical officers in this way has a poten- hazard depends on sound design, specifica- tial longevity that is generally not matched by tions, and construction. MoSSaiC involves elected political representatives. developing surface water drainage plans to MCU roles and responsibilities in this reduce landslide hazard and construction by regard are as follows: community-based contractors to achieve that • Create strong horizontal and vertical inte- goal. The MCU must therefore create strate- gration among senior civil servants, task gies for quality control and monitoring of the teams, and communities drainage design and implementation process; this responsibility is pivotal to the success of • Evaluate project outcomes (medium-term the measures. impacts and sustainability) as well as the MCU roles and responsibilities in this standard outputs required by donors regard are as follows: • Engage the community in assessing project • Select appropriately skilled task teams for successes and failures, in developing new mapping, landslide hazard assessment, and approaches and solutions, and in sharing drainage design experiences and expertise • Select experienced site supervisors • Promote the approach based on physical demonstration of good slope management • Establish an appropriate community con- practices, using project evaluations to tracting process and oversee the supervi- develop an evidence base for raising aware- sion of contractors ness and for leveraging further funding 4. Evaluate the project and develop sustainable • Provide regular updates to key senior civil practices servants and engineers, using photos, site visits, and short presentations or reports The success of the MoSSaiC project should not be measured simply in terms of the quality • Find a niche for the approach within the and quantity of immediate outputs (such as most appropriate government ministry or the length of drains built, number of house- agency holds benefiting, or money spent on employ- 5. Adhere to safeguards ing local contractors), but in terms of medium- term impact and sustainability (outcomes). The MCU must ensure that the project com- The MCU should thus monitor and evaluate plies with relevant safeguards and protocols the project beyond its immediate outputs. The stipulated by a donor or by the government or observations and experiences of the commu- dictated by good practice (section  1.5.3), nity are a vital resource in this regard. although it is recognized that formal responsi- The sustainability of the project is bility for compliance may well lie elsewhere. reflected in the degree of uptake by commu- Table 1.16 (chapter 1) illustrates some typical nity and government teams—the creation of safeguards that might apply. These should not a culture of good slope management prac- be viewed as comprehensive and are not 6 4    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S intended to be a substitute for binding policies projects. In a survey of the World Bank Devel- and procedures. opment Research Group, Mansuri and Rao MCU roles and responsibilities in this (2003) found that projects are often under- regard are as follows: taken with young, inexperienced facilitators whose incentives are not aligned with the best • Be fully conversant with the safeguards that interests of the community. This finding rein- apply to the project forces the critical role of the MCU and the • Communicate safeguards and processes for nature of its membership. compliance to relevant stakeholders • Keep a record of compliance MILESTONE 2: 2.3.3 MCU membership MoSSaiC core unit formed; key responsibilities agreed on and MCUs will vary in structure from country to country. Typically, members might be drawn defined from the following government departments, ministries, and agencies: • Public works 2.4 IDENTIFYING THE • Social development GOVERNMENT TASK TEAMS • Planning • Finance Part of the MCU’s first mission is to develop • National emergency organization teams dedicated to specific project tasks that • Statistics and census will ensure the delivery of appropriate physi- • Agriculture cal measures to reduce the landslide hazard. • Water and sewerage company Identification and initial engagement of Higher education and community colleges task team members will probably be an itera- (where there is relevant technical expertise tive and consultative process in conjunction that would be of value) may also contribute with the development of specific project steps. MCU members. In many cases, MCU members themselves Members selected should be fully conver- may be the most appropriate people to con- sant with and supportive of the MCU mis- tribute to or lead a particular task team. sions, roles, and responsibilities as outlined Each MCU member will need to identify above. They should be committed to deliver- and consult with expert practitioners (engi- ing landslide risk reduction measures using an neers, officials, and technicians) in their interdisciplinary, community-based approach. respective ministries to MCU members need to be able to command • identify motivated, knowledgeable, and respect from the communities, government, skilled individuals who want to contribute donors, and media (Anderson and Holcombe to the overall vision of achieving landslide 2004, 2006a, 2006b; Anderson, Holcombe, hazard reduction in communities; and and Williams 2007). MCU members need to stay fully engaged • consult with these individuals to identify throughout the project; if they do not, believ- cross-ministry collaborations and specific ing that the project has been established and is steps that they (as part of the ministry or to some degree running itself, project outputs agency) would need to undertake for proj- will suffer as a consequence. ect success. Qualitative evidence suggests that the role of project facilitators (MCU members in this Table 2.5 provides guidance on factors rele- case) is key to the success of community-based vant to the team selection process. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    6 5 TAB L E 2 .5  Government task team selection factors FACTOR COMMENT Team size Typically, each government task team consists of about three individuals who display commitment to the vision. With six task teams, this totals about 18 government task team members in all. Team leaders may also be part of the MCU. Financial Experience has shown that it is not necessary for the respective government departments/agencies from compensation which the team members were drawn to receive financial compensation. Such a circumstance can be seen as increasing ownership of the vision. Time Depending on the scale of the intervention, it is unlikely that any team member role will, on average, be full commitment time. However, there may be periods when the individual is working full time for a few days. Convening of MCU members, having been chosen with regard to their respective specialization (section 2.3.3), search for team members and identify potential task team members. This process will entail both taking advice on suitable members as well as discussing opportunities with potential individuals. Membership In establishing the teams, it may be useful to achieve a mix of middle-management members (to deliver composition skills) combined with a modest number of more senior officials to drive policy acceptance. Housing of the It is appropriate to seek an office location for the MCU (perhaps a ministry office or a relevant agency in MCU which there is administrative support and in which there may be a top-level advocate for MoSSaiC). This helps demonstrate government support for the MCU and assists in project implementation. This section identifies typical areas of proj- enced task team leaders will need to take ect activity for which motivated and experi- responsibility (table 2.6). The task team leader TAB L E 2 .6  Task teams and guidance notes TYPICAL EXPERIENCE/POSITION OF CHAPTER TEAM MAIN TASK TASK TEAM LEADER SECTION Mapping Produce high-resolution maps for landslide Geographic information system (GIS), hazard assessment planning, and census officials 2.4.1 Community Develop community prioritization method Community development 2.4.2 liaison with mapping team Landslide Map landslide and drainage hazard, advising Scientists or engineers with expertise in assessment and the MCU of the appropriateness of the landslide risk assessment and hydrology GOVERNMENT- engineering MoSSaiC approach and overseeing the Civil engineers, especially with expertise 2.4.3 BASED preparation and letting of work packages in drainage, environmental engineering, bioengineering, design, and contract management Technical Site survey work and site supervision GIS, census, computing, surveying, support materials laboratory technicians, 2.4.4 supervision of works Communications Support the MCU in raising public awareness Media, public relations 2.4.5 Advocacy Engage with other decision makers and the Elected officials, funding agency represen- media to explain the MoSSaiC vision and its tatives 2.4.6 practical implementation Residents Assist all government teams on the ground in Residents, community leaders, and groups 2.5.1 COMMUNITY- their community BASED Community Provide detailed community context to the Community-elected officials 2.5.1 representatives MCU and other task teams Construction Community contractors provide knowledge Contractors 2.5.2 of local practices and undertake the works 6 6    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S will need to work closely with the MCU to important to identify the ministry with the design the project steps and build the team. most skilled individual(s) and the main reposi- Each task team may comprise individuals from tory of digital maps (such as topography, soils, other ministries with the necessary skills to geology, housing/landownership, and land undertake the assigned tasks. This informa- use) and aerial images. The ministry responsi- tion is provided as guidance only; specific cir- ble for planning is often the most appropriate cumstances may dictate variations depending host agency for this team. However, other on the local roles held by individuals in a par- ministries may be able to contribute data and ticular country. expertise in specific areas such as census information relating to poverty and the vul- 2.4.1 Mapping task team nerability of communities. Consider including The key responsibilities of the mapping task representatives from such groups on the team team are as follows: to ensure optimal coordination of both data assimilation and presentation. • Integrate any available spatial data on pov- erty and landslide susceptibility to support 2.4.2 Community liaison task team the process of identifying and prioritizing The key responsibilities of the community liai- communities for landslide risk reduction son task team are as follows: • Produce high-resolution maps of selected • Coordinate with the mapping team to communities to serve as the basis for the develop a transparent method for prioritiz- community-based mapping of slope fea- ing vulnerable communities tures, landslide hazard, and proposed drain locations. • Identify for the mapping team any social surveys or other data that would be helpful There may be many government depart- in the prioritization process ments that make use of geographic informa- • Coordinate with communities to identify tion system (GIS) technology (figure 2.2). It is community representatives • Act to moderate political or other motives FI G U R E 2 .2  Mapping team from a national for selecting certain communities, commu- disaster management agency demonstrates GIS software to MCU team leader nity representatives, or contractors • Coordinate with community residents and representatives throughout the project (fig- ure  2.3)—organizing informal and formal meetings and any public awareness materi- als that might be relevant • Bring knowledge of how the community works to the MCU • Ensure that the other teams engage with the community at each project stage. The role of the community liaison team is to ensure that communities are represented and engaged in the community selection process, mapping and intervention design, implemen- tation of measures, and any subsequent follow- up. This team may need to be part of other task team activities as the project progresses. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    6 7 reducing landslide hazard in the commu- F IG U R E 2 . 3  Coordinating with Social nity Development Ministry and community residents on site • Engage and coordinate with additional spe- cialists (such as ground and quantity sur- veyors) • Design surface drainage measures, gener- ate work packages, and manage the con- tracting process to engage contractors from the community in construction • Ensure the quality of the works (to be man- aged by an experienced site supervisor). Successful reduction of landslide hazard depends on correct identification and assess- ment of the hazard, and design of appropriate 2.4.3 Landslide assessment and mitigation measures (surface drainage, in the engineering task team case of MoSSaiC). The landslide assessment The key responsibilities of the landslide and engineering task team should include at assessment and engineering task team are as least one civil or environmental engineer and follows (figure 2.4): any other government staff member with a background in and working knowledge of the • Direct the mapping team in the analysis of physical, geotechnical, and hydrological sci- available data on landslide susceptibility ences. and hazard to assist in community selec- In many countries, residents and govern- tion ment agencies will report landslide and drain- • Undertake community-based mapping of age issues to a specific government ministry. This ministry, which is often responsible for slope features; landslide hazard and drain- civil works, is likely to be the most appropriate age issues; and assessment of the location, one for fulfilling the key responsibilities out- magnitude, and cause of the hazard lined above. It will also have the necessary pro- • Appraise the MCU of the relevance and cesses and personnel to implement construc- potential cost-effectiveness of MoSSaiC in tion of landslide hazard reduction measures. F IG U R E 2 .4  Examples of landslide assessment and engineering task team responsibilities a. Assess different slope stabilization options. b. Design drain dimensions and alignment in complex topography. 6 8    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S 2.4.4 Technical support task team ate communications for use within the communities The key responsibilities of the technical sup- • Communicate project aims and progress to port task team (figure 2.5) are as follows: the wider public • Provide technical support to other teams in • Engage and manage media interest—from data acquisition, processing, and presenta- newspapers, radio, television—in the form tion of interviews of team and community mem- • Provide field support to other teams—e.g., bers, press releases, information on good undertaking ground or quantity surveys, or slope management practices, and other assisting in monitoring and evaluation coverage of the project. • Provide site supervision during implemen- The appropriate communication of land- tation of works slide issues, good slope management prac- • Suggest ways of working that would tices, and project aims and progress can improve on-the-ground implementation. encourage MoSSaiC uptake and sustainabil- ity. In many communities, the main form of Generally, skilled government technicians communication is word of mouth, often stay in a given role for long periods. Therefore, informed by some combination of commu- investment in their skills and inclusion in the nity meetings, radio, and television (fig- wider MoSSaiC project can encourage good ure 2.6). slope management practices to be embedded The MCU should decide on the message in government beyond the end of the project. it wishes to convey to the selected commu- nities and the public, and how that message is to be conveyed. The communications task FI G U R E 2 .5  Technical team training course team may consist of existing government attendees: Sharing and developing expertise information service personnel who will across ministries engage the media at different stages of the project. In some cases, it may be possible to secure the services of either the government or a pri- vate production company to make a short doc- umentary on the project. The project will thus receive coverage in a professional manner, thereby lengthening the “shelf life” of public awareness of good slope management prac- tices. 2.4.6 Advocacy task team Political advocacy 2.4.5 Communications task team Elected officials would most likely have been The key responsibilities of the communica- party to the original decisions to undertake the tions task team are as follows: MoSSaiC project; they should be kept informed at all project stages. A policy entrepreneur may • Support the MCU with regard to public emerge as an advocate for MoSSaiC—keeping awareness of the project landslide risk reduction on the political agenda • Produce leaflets, posters, invitations to and helping streamline funding and political community meetings, and other appropri- processes for the initiative. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   69 F IG U R E 2 . 6  Aspects of communication a. Have a clear and agreed-upon message to b. Consider commissioning a documentary in communicate at the start of a project. which community residents tell the project’s story (source: Government of Saint Lucia). The MCU has a key role to play in develop- A change in government may mean that ing a strategy of engagement with politicians, what was once perceived as innovative policy which could include the following: (such as undertaking MoSSaiC projects) may be less attractive politically. Thus, connecting • Presenting progress documents at cabinet/ the MCU with senior civil servants and techni- government committee meetings cal officers is central to achieving a sustained and sustainable landslide mitigation policy. • Maintaining a one-to-one dialogue with government ministers who have adopted Politicians and the media the vision to reduce landslide risk Politicians may take ownership of the project • Organizing site visits when work is under and promote it—although sometimes this will way, including receiving feedback from be to achieve a political agenda not necessarily community residents in accord with the technical aspects of com- munity prioritization. • Conducting on-site briefings at which com- Combining the media and elected officials pleted works are presented to government can be a very powerful vehicle for project pro- ministers; this can be a powerful tool in motion, especially in the early to mid-stages of a encouraging policy change (figure 2.7). project cycle. The MCU has a key role in brief- ing politicians so that they own the key mes- sages (figure 2.8), and should develop specific F IG U R E 2 .7  On-site briefing plans for coordinated media opportunities. Funding agency advocates It should be assumed that it is a formal require- ment to keep the funding agency appraised of project progress ; this reporting is usually stan- dardized. There is additional benefit in main- taining less formal communications with both current funders and similar agencies to publi- cize project innovation, success in delivering landslide hazard reduction measures on the ground, and lessons learned. Informal visits, 70    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S 2.5 IDENTIFYING THE FI G U R E 2 .8  Media film elected officials COMMUNITY TASK TEAMS during a MoSSaiC project 2.5.1 Community residents The key responsibilities of community resi- dents with regard to MoSSaiC are as follows: • Discuss and influence project conceptual design—the specific form of community participation and community contracting processes will vary depending on local community structures • Provide detailed local knowledge on past landslides, slope features and processes, possibly with a media component (figure 2.9), rainfall impacts, and drainage issues can help maintain a funding agency’s advocacy • Select representatives from the community of MoSSaiC, especially if funding agency staff to interface with the government task teams turnover is significant. The MCU should create and encourage • Make in-kind contributions to project links with funding agency staff in order to implementation, or earn money as part of a contractors’ team • raise international awareness of a country program, • Learn about good slope management prac- tices and put them in use wherever possi- • potentially provide links to other funding ble. sources, Frequently, the first engagement of com- • provide an opportunity to exchange best munity residents in the project will be infor- practices, and mal as part of initial government task team • build self-esteem among those engaged in site visits to confirm the selection of commu- MoSSaiC at the community level—residents nities for the project. These initial visits are and team members alike would not other- good for opening up discussions with resi- wise gain exposure to such groups or be dents in a nonthreatening way, but formal able to express their perceptions and first- communication with the community should hand project knowledge to them. also occur early on. It is important to identify existing community-based organizations and formal community leadership structures that FI G U R E 2 .9  Funding agency staff on site at initial stage of MoSSaiC project may be required to endorse (or facilitate) a MoSSaiC project. Having established an appropriate means for engaging with the community, a meeting should be held to pres- ent and discuss the proposed project (fig- ure 2.10a). This meeting will often be a multi- purpose event, with media and local government representatives also in atten- dance. These formal and informal occasions give residents the opportunity to express their views and begin to select a group of commu- nity representatives for the project. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    7 1 Informal opportunities should be created ping, design, and implementation phases so for community residents to contribute to the that local knowledge is captured and acted project on an individual or small-group basis. upon where relevant in the construction Meetings should literally be taken to the com- phase, and the intervention is owned by resi- munity in the form of walk-throughs and dents. Continued community engagement also impromptu discussions. Gathering at a visible provides the best foundation for ongoing drain site in the community encourages others to cleaning and maintenance. join the group out of curiosity as they pass Community representatives (figure  2.10b). In this way, residents effec- • directly interface with government task tively become a task team, contributing their teams as spokespersons for the community; knowledge of slope features and drainage issues. • assist in the mapping of landslide hazard Both informal and formal engagements and drainage issues; allow community members to provide a sig- • collaborate with the community liaison nificant amount of detailed local knowledge team to organize informal and formal com- throughout the project, such as the height the munity meetings (figure 2.10d); flow in a drain might have reached in a partic- ular rainfall event (figure 2.10c). This engage- • collaborate with the engineering task team ment should continue throughout the map- to identify potential contractors and work- F IG U R E 2 .1 0  Aspects of community resident involvement in MoSSaiC a. Meeting with residents at the start of a project b. An informal community focus meeting is often can produce enthusiasm from members of the the best way to begin a project. community to actively participate in the project. c. Residents can help postproject impact assess- d. A formal community meeting is often most ment by indicating maximum observed water levels effective when held after initial informal on-site in completed drains after heavy rainfall. meetings. 7 2    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S ers from the area, monitor the works, and potentially bidding on the final work packages. report any problems; and A list of contractors from within or near the community should be compiled; they may • communicate and demonstrate good slope have attended a community meeting or have management practices to residents. been recommended. They should be invited to Community-elected leaders can provide participate in the bid process, as part of an useful information when communities are in agreed-upon community contracting process the process of being selected for interventions, (figure 2.11). as well as at the start of a potential project. Such individuals can play a key role in champi- oning the project, given their strong commu- F IGUR E 2 .11  Briefing potential contractors nity engagement and links with government on site after calling for expressions of and agency officials. interest from within the community If appropriate, the community contracting process may involve a selected (and trained) group of community leaders and residents managing the contracting and procurement process with support from the government task teams. Alternatively, if the government handles this process, community leaders and residents should be included as fully as possible. 2.5.2 Construction task team The key responsibilities of the construction task team are as follows: Contractors should be supervised by the • Provide local knowledge as part of the com- engineering and technical task teams during munity mapping process implementation of the works; they may also • Provide insight into local construction have a role in training government technicians practices and designs, and how they could and demonstrating good practices to other potentially be used in the engineering task contractors or communities (figure 2.12). Time team’s design should be invested in community-based con- tractors because of the vital role they play in • Assist in the consideration of transport and vulnerable communities. safe storage of materials, and advise on approximate implementation times 2.5.3 Landowners • Undertake specific works (construction of Building drains and related interventions on drains, installation of household gray water slopes demands that landownership be known and roof water connections) as detailed in to the MCU and that adequate safeguards be contracts put in place to ensure that there will be no dis- putes before, during, or after construction. In • Coordinate with engineering and technical unauthorized housing areas, the following task teams (especially the site supervisor) to landownership possibilities are likely to exist: ensure correct implementation and quality • Single landowner (who possibly resides • Employ workers from within the commu- overseas) who rents out houses, or plots of nity. land for building on, to individual house- holds Locally based contractors can make a vital contribution to the design of works, as well as • Government-owned land CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   73 agency structures. The MCU could, for exam- F IG U R E 2 .1 2  Contractor briefs government ple, be hosted by a ministry through which it technical officers on project implemented in reports. Conversely, in cases where MoSSaiC is his community adopted as a national program, the MCU may report directly to the government. MoSSaiC should not create parallel structures within the government; rather, it should create a manage- ment structure that works with existing roles of accountability wherever possible. Individ- ual MCU members can be delegated to manage the government task team, reflecting their interest and adding value to their existing roles. The government teams should work with the community, within the broad roles defined above, to allow the most marginalized and vul- nerable communities to • have ownership, as they are explicitly engaged in the initial landslide risk map- ping exercise; • provide project guidance, as they are involved in the prioritization of works in their own community; • Multiple landowners with family land par- titioned as families grow and houses are • undertake construction, as contracting built on subdivided land parcels. workers from within the community is an integral part of implementation; The MCU should take particular care to • export the methodology, as community obtain, review, agree on, and implement rele- members provide guidance and support to vant safeguard policies (sections 1.5.3 and 2.3.2). neighboring communities; and • gain self-esteem, as they participate in pro- viding on-site community training to gov- 2.6 INTEGRATION OF MoSSaiC ernment community officials and deliver TEAMS AND PROJECT STEPS presentations at relevant international con- ferences. 2.6.1 Team structure and reporting lines The broad team management structure in Once the task teams have been established, the figure  2.13 highlights the central role of the MCU should prepare a summary document MCU in the management process. listing the selected teams, naming team mem- bers, and assigning broad roles and responsi- 2.6.2 Integrating teams with project bilities; table 2.6 could be used as a template. steps Defining roles and responsibilities is impor- Once all the teams are in place, the MCU can tant in ensuring that project safeguards are create a template that sequences the necessary owned by the relevant task team or the MCU as steps for project implementation. The nine appropriate. It also helps prevent mission drift. components of MoSSaiC (section 1.4.5) can be The MCU should have a reporting line to the used as the basis for the template. government. The exact nature of this reporting Each of the project steps needs to be line will depend on local government and assigned to one or more task team. The par- 74    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S FI G U R E 2 .1 3  Typical MoSSaiC team reporting structure GOVERNMENT TASK TEAMS COMMUNITY TASK TEAMS Community #1 teams: Mapping team Residents, representatives, construction Community #2 teams: Community liaison team Residents, representatives, construction Community #3 teams: Landslide assessment and Residents, representatives, engineering team MCU construction Government  Policy maker  MCU chair  members   Community #4 teams: Technical support team Residents, representatives, construction Community #5 teams: Communications team Residents, representatives, construction Advocacy team … ticular government and community task team to take responsibility of relevant steps will F IGUR E 2 .14  User group forum activities depend on local conditions. A central role for the MCU is to design, consult on, agree to, and communicate the project steps. The steps shown in table 2.7 (on the following pages) are illustrative of those that have been used in MoSSaiC programs in the Eastern Caribbean; these should be discussed and adapted as local conditions dictate. It is good practice to identify milestones for the project and assimilate them into the agreed-upon project steps. a. A regional workshop captures project outcomes and identifies potential process Table 2.7 integrates summary information improvements. on MoSSaiC teams (sections 2.3 and 2.4), proj- ect steps (section 1.4.5), and milestones. 2.6.3 Establishing a user group community Establishing a user group forum might be use- ful in enabling MoSSaiC to improve slope management practices (achieve behavioral change) as a medium-term outcome. Both local and regional workshops have proved to be a powerful vehicle for senior politicians, b. Community contractors address a workshop contractors, residents, and the media from dif- attended by community residents and other ferent countries to share experiences and stakeholders. develop best practices (figure 2.14). CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   75 TAB L E 2 .7  Summary template of MoSSaiC project teams, steps, and milestones TEAM F M G C ACTIVITY/STEP/MILESTONE CHAPTER  Funding for pilot, project, or phase 2 (carried over or levered from existing projects)     Understand the disaster risk context with respect to landslides; relevance of MoSSaiC approach to local landslide risk context identified     Understand the innovative features and foundations of MoSSaiC 1   Identify general in-house expertise and the appropriate institutional structures for codifying a local approach toward landslide risk reduction    Brief key individuals on MoSSaiC (politicians, relevant ministries, in-house experts)    MILESTONE 1: Key catalytic staff briefed on MoSSaiC methodology    MILESTONE 2: MoSSaiC core unit formed: key responsibilities agreed and defined  Establish the MCU; define and agree on key responsibilities   Identify and establish government task teams; define and agree on key responsibilities 2    Identify and establish community task teams; define and agree on key responsibilities   Agree on a general template for project steps    Gain familiarity with different landslide types and how to identify those that may be addressed by MoSSaiC    Gain familiarity with slope processes and slope stability variables 3   Gain familiarity with methods for analyzing slope stability    MILESTONE 3: Presentation made to MoSSaiC teams on landslide processes and slope stability software   Define the community selection process  Assess landslide hazard  Assess exposure and vulnerability  Assess landslide risk 4   Select communities   Prepare site map information for selected communities    MILESTONE 4: Process for community selection agreed and communities selected    Identify the best form of community participation and mobilization  Include key community members in the project team  Plan and hold a community meeting   Conduct the community-based mapping exercise; this will entail a considerable amount of time in the community   Qualitatively assess the landslide hazard and potential causes 5   Quantitatively assess the landslide hazard and the effectiveness of surface water management to reduce the hazard  Identify possible locations for drains   Sign off on the initial drainage plan: organize a combined MCU-community walk-through and meeting to agree on the initial drainage plan MILESTONE 5: Sign-off on prioritized zones and initial drainage plan (continued) 76    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S TAB L E 2 .7  Summary template of MoSSaiC project teams, steps, and milestones (continued) TEAM F M G C ACTIVITY/STEP/MILESTONE CHAPTER   Identify the location and alignment of drains  Estimate drain discharge and dimensions   Specify drain construction and design details  Incorporate houses into the drainage plan 6   Produce final drainage plan    Stakeholder agreement on plan    MILESTONE 6: Sign-off on final drainage plan   Prepare work package and request for tender documentation   Conduct the agreed-upon community contracting tendering process   Implement construction 7  Sign off on completed construction    MILESTONE 7: Sign-off on completed construction    Understand how new practices are adopted  Design a communication strategy   Design a capacity-building strategy 8    Plan for postproject maintenance  Map out the complete behavioral change strategy    MILESTONE 8: Communication and capacity-building strategies agreed on and implemented  Agree on key performance indicators (KPIs) for immediate project outputs  Agree on KPIs for medium-term project outcomes 9   Undertake project evaluation MILESTONE 9: Evaluation framework agreed upon and implemented F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors Note: The steps listed for chapters 8 and 9 are relevant throughout the project. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    7 7 2.7 RESOURCES 2.7.1 Who does what CHAPTER TEAM RESPONSIBILITY ACTIONS AND HELPFUL HINTS SECTION Funders and • Understand MCU missions, roles, and responsibilities 2.2; 2.2.4; policy makers • Identify MCU team members from relevant government 2.3.3; 2.6 ministries and other agencies Establish the MCU Helpful hint: Look for potential members who will command respect and be advocates of MoSSaiC, rather than simply represent particular interests. Coordinate with the MCU MCU Own and communicate the • Understand MCU missions, roles, and responsibilities 2.2 MoSSaiC vision Identify and form government • Identify task team members from relevant government 2.4 task teams ministries and other agencies Once community selected • Initiate community participation process; engage with 2.5 (chapter 4), identify community community residents and representatives task team members • Review MoSSaiC components with respect to task team 2.2.4; 2.6 capacity and resources • Modify project step template Establish project step template Helpful hint: This is a vital step in the process of project inception. Organize a meeting to review the template and encourage the modification of the template to fit local conditions and protocols. Coordinate with new task teams Government task Provide the MCU with assess- • Become familiar with MoSSaiC approach and local context 2.2; 2.2.4 teams ment of task team capacity for • Identify specific team skills and resources for project each project step delivery Coordinate with the MCU Community task • Become familiar with MoSSaiC approach with respect to 2.5 Once community selected teams community context (chapter 4), coordinate with relevant government task teams • Advise on existing community-based leadership and the MCU to identify structures and organizations appropriate form of community • Identify specific community-based skills and resources participation • Attend community meetings Coordinate with government task teams 78    C H A P T E R 2 .   P RO J E C T I N C E P T I O N : T E A M S A N D ST E P S 2.7.2 Chapter checklist SIGN- CHAPTER CHECK THAT: TEAM PERSON OFF SECTION 99List compiled of individuals supportive of MoSSaiC across government/agencies 2.3.3 99Milestone 2: MCU formed 99MCU has identified individuals for government task teams 2.4 99MCU and appropriate government task teams have identified individuals for 2.5 community task teams 99MCU has established clear line of responsibility to a specific government entity 2.6 99All necessary safeguards complied with 1.5.3; 2.3.2 2.7.3 References Magazine 19 (3). http://practicalaction.org/ Anderson, M. G., and E. A. Holcombe. 2004. practicalanswers/product_info.php?products_ “Management of Slope Stability in id=214. Communities.” Insight 1: 15–17. Ostrom, E., C. Gibson, S. Shivakumar, and —. 2006a. “Purpose Driven Public Sector Reform: K. Andersson. 2001. “Aid, Incentives, and The Need for within-Government Capacity Build Sustainability: An Institutional Analysis of for the Management of Slope Stability in Development Cooperation.” Sida Studies in Communities (MoSSaiC) in the Caribbean.” Evaluation Report 02/01, Stockholm. Environmental Management 37: 5–29. Prater, C. S., and M. K. Londell. 2000. “Politics of —. 2006b. “Sustainable Landslide Risk Natural Hazards.” Natural Hazards Review 1 (2): Reduction in Poorer Countries.” Proceedings of 73–82. the Institution of Civil Engineers—Engineering Raschky, P. A., and M. Schwindt. 2009. “Aid, Sustainability 159: 23–30. Natural Disasters and the Samaritan’s Anderson, M. G., E. A. Holcombe, and D. Williams. Dilemma.” Policy Research Working Paper 2007. “Reducing Landslide Risk in Poor Housing 4952, World Bank, Washington, DC. Areas of the Caribbean—Developing a New Roberts, N. C., and P. J. King. 1991. “Policy Government-Community Partnership Model. Entrepreneurs: Their Activity Structure and Journal of International Development 19: 205–21. Function in the Policy Process.” Journal of Buchanan, J. M. 1977. “The Samaritans’ Dilemma.” Public Administration Research and Theory 1 (2): In Freedom in Constitutional Contract, ed. J. M. 147–75. Buchanan. College Station, TX: Texas A & M University Press. UNDP (United Nations Development Programme). 2006. “A Review of Selected Capacity IEG (Independent Evaluation Group). 2000. “IEG Assessment Methodologies.” http://lencd.com/ Report on Project ID P003985 Indonesia.” data/docs/242-A%20Review%20of%20 World Bank, Washington, DC. Selected%20Capacity%20Assessment%20 —. 2005. Putting Social Development to Work Methodologies.pdf. for the Poor: An OED Review of World Bank Venture Philanthropy Partners. 2001. Effective Activities. Washington, DC: World Bank. Capacity Building in Nonprofit Organizations. Mansuri, G., and V. Rao. 2003. Evaluating http://www.vppartners.org/sites/default/files/ Community-Based and Community-Driven reports/full_rpt.pdf. Development: A Critical Review of the Evidence. —. 2003. Strategic Communication for Development Research Group. Washington, Development Projects: A Toolkit for Task Team DC: World Bank. Leaders. http://siteresources.worldbank.org/ Maskrey, A. 1992. “Defining the Community’s Role EXTDEVCOMMENG/Resources/ in Disaster Mitigation.” Appropriate Technology toolkitwebjan2004.pdf. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   79 “A failure to address the underlying risk drivers will result in dramatic increases in disaster risk and associated poverty outcomes. In contrast, if addressing these drivers is given priority, risk can be reduced…” —United Nations, “Global Assessment Report on Disaster Risk Reduction” (2009, 4) CHAPTER 3 Understanding Landslide Hazard 3.1 KEY CHAPTER ELEMENTS 3.1.1 Coverage This chapter identifies the physical and human Slope Stability in Communities) foundations. drivers for landslide hazard. Understanding The listed groups should read the indicated the scientific basis for assessing landslide haz- chapter sections. ard is one of the MoSSaiC (Management of AUDIENCE CHAPTER F M G C LEARNING SECTION    How to identify types of landslides that can be addressed by MoSSaiC 3.3   Slope stability factors and common landslide hazard assessment methods 3.4    Detailed localized factors that affect slope stability in communities 3.5   Specific scientific landslide hazard assessment methods relevant to MoSSaiC 3.6 F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors 3.1.2 Documents CHAPTER DOCUMENT TO BE PRODUCED SECTION Briefing by landslide assessment and engineering task team for the MoSSaiC core unit and all 3.2–3.5 other task teams on (1) MoSSaiC applicability to local landslide types; (2) landslide preparatory, aggravating, and triggering factors; and (3) the scientific basis for assessing slope stability, especially with respect to locally available expertise and software 81 3.1.3 Steps and outputs STEP OUTPUT 1. Gain familiarity with different landslide types and how to identify MoSSaiC core unit (MCU) and those that may be addressed by MoSSaiC task teams understand the • Review landslide process introductory material in this book and types of landslide risk for other sources which MoSSaiC is applicable 2. Gain familiarity with slope processes and slope stability variables MCU and task teams can • Review landslide process variables as introduced in this book identify different levels of landslide hazard and underlying physical causes 3. Gain familiarity with methods for analyzing slope stability MCU and task teams can • Review slope stability software as introduced in this book and provide scientific rationale for other sources landslide mitigation measures Those on the MoSSaiC landslide assessment there are few examples of effective physical and engineering task team with the most expe- landslide hazard reduction measures in such rience in analysis of landslide risk could use communities (Wamsler 2007). the material in this chapter to organize a pre- Development agencies have mainstreamed sentation to the MoSSaiC core unit (MCU) and disaster risk management policies, estimating other task teams to foster a common and that for every dollar spent in mitigation, two to shared understanding of landslide triggering four dollars will be saved in avoided costs processes, the relevance of MoSSaiC (chap- (Mechler 2005). Landslide risk mitigation ter 1), and the associated project structure and requires an understanding of the interactions implementation steps (chapter 2). between physical and human risk drivers, and how to assess the risk and deliver solutions at a 3.1.4 Community-based aspects scale that relates to these risk drivers. Com- The chapter outlines the need to understand munity-scale landslide hazard reduction can landslide triggering mechanisms at the house- only be successful if landslide hazard mecha- hold/local scale within communities. nisms and triggers are understood. Such an understanding 3.2 GETTING STARTED • ensures that any landslide risk assessment is scientifically informed, 3.2.1 Briefing note • ensures that any proposed landslide risk Importance of understanding landslide management strategies are appropriate to processes the specific local landslide hazards, Both the occurrence and the impact of land- • determines if a MoSSaiC-style drainage slides are increasing, especially in tropical intervention will address the landslide haz- developing countries (Charveriat 2000; UNDP ard, 2004), with the majority of landslide fatalities • increases the ability of those implementing occurring in urban areas (Petley 2009; UN the project to justify the risk reduction 2006). Here, intense rainfall triggers land- measures adopted, slides in highly weathered soils and rapid urbanization increases the susceptibility of • helps build confidence within the commu- slopes to failure, while socioeconomic vulner- nity that the fundamental causes of risk are ability increases the damage caused. Even so, being tackled, and 82    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D • encourages a holistic and strategic approach grams focus on assessing vulnerability and to implementation of landslide risk reduc- exposure to landslide hazards; relatively few tion measures among all stakeholders. look at the physical causes of the hazard at the highly localized scales at which they occur. Landslide hazard as a component of landslide Various natural and human preparatory and risk aggravating factors can reduce slope stability Three components contribute to landslide and trigger landslides. By understanding these risk: the physical landslide hazard (its likeli- driving factors and identifying the dominant hood, location, and magnitude), the exposure landslide mechanisms, it is often possible to of different elements (such as people, build- address the root causes of landslides and thus ings, public utilities, economic infrastructure, reduce the hazard (the frequency or magni- or the environment) to that hazard, and the tude of the event). vulnerability of those elements to damage by One of the main premises of MoSSaiC is the hazard. that rainfall-triggered landslide hazards can often be reduced in vulnerable communities in • Landslide hazard is defined in terms of its developing countries. This is because a com- frequency (e.g., an annual probability of 0.1, mon driver for such landslide hazards is poor meaning a 1-in-10-year landslide event), slope drainage and surface water infiltration magnitude, and type at a particular location into weathered slope materials on densely or within a wider region. When the likeli- populated urban slopes. Scientific principles hood of a particular landslide hazard is and methods can be used to confirm the role of expressed in relative or qualitative terms surface water infiltration and therefore indi- rather than as a probability, it is more cate a potential solution—the construction of appropriate to refer to susceptibility (more appropriately located surface water drains. versus less susceptible to landslides). Science as part of the landslide risk • The exposure of people, structures, ser- management process vices, or the environment to a specific land- slide hazard is determined by the spatial A typical disaster risk management process and temporal location of those elements was introduced in section 1.3.2. Table 3.1 pres- with respect to the landslide. ents the scientific basis of each step in this pro- cess with particular reference to landslide risk • Vulnerability is an expression of the poten- management and the MoSSaiC approach. tial of the exposed elements to suffer harm or loss. Thus, exposure and vulnerability 3.2.2 Guiding principles relate to the consequences or results of the The following guiding principles apply in landslide, and not to the landslide process understanding landslide hazard: itself (Crozier and Glade 2005). In many cases, exposure is treated as an implicit part • Develop a shared understanding of land- of vulnerability assessment. Vulnerability is slide processes within the MCU related to the capacity to anticipate a land- • Identify and collate data on past, existing, slide hazard, cope with it, resist it, and or predicted landslide hazards in the proj- recover from its impact. A combination of ect area and on physical and human factors physical, environmental, social, economic, relating to slope stability political, cultural, and institutional factors determine vulnerability (Benson and Twigg • Explain and explore the scientific ratio- 2007). nale for landslide hazard reduction in a To understand landslide risk, it is necessary way that is accessible to residents in vul- to understand the nature and causes of the nerable communities; assure residents hazard. Many development studies and pro- that the local landslide processes are CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    8 3 TAB L E 3 .1  Typical landslide risk management project steps and associated scientific basis for MoSSaiC STEP MoSSaiC SCIENCE BASE Landslide Identify and Confirm the relevance of MoSSaiC. A basic understanding of landslide types and triggers is risk formulate the needed in order to identify the dominant landslide hazard in the project area. MoSSaiC management project specifically addresses rainfall-triggered rotational/translational landslides in weathered project materials. preparation Identify the Identify communities most at risk from landslides. This requires assessment of the relative broad landslide rotational/translational landslide susceptibility or hazard in different areas. This hazard risk information is combined with an assessment of community exposure and vulnerability. Landslide Understand and Identify the underlying landslide hazard drivers and confirm the level of the hazard. For risk estimate the selected communities, the local slope features and slope stability processes must be identified, assessment specific science-based methods used to confirm the hazard drivers, and the vulnerability of exposed landslide risk households assessed. Evaluate the risk Compare the landslide risk with other risks. Expert judgment and/or scientific methods should be applied to determine where investment in landslide risk reduction is a priority. Identify disaster Determine whether the landslide hazard can be reduced. Disaster risk reduction options risk reduction include avoiding or reducing the hazard, reducing vulnerability, or transferring the risk. MoSSaiC options focuses on landslide hazard reduction through appropriate surface water management measures. For each community, expert judgment and/or scientific methods should be applied to confirm whether this MoSSaiC approach will be effective. Plan the risk Design the landslide hazard reduction measures. Engineers should design the physical Landslide mitigation measures to directly address the localized landslide hazard drivers. In the case of MoSSaiC, this risk requires appropriate alignment and design of a drainage network to capture surface water and reduction reduce infiltration. Implement risk Construct landslide hazard reduction measures. This involves issuing contracts for and mitigation managing construction, and raising public awareness. Knowledge of slope processes and construction of drainage works are vital in ensuring that hazard reduction measures are correctly implemented. Monitor and Assess project progress, sustainability, and impact. Science-based methods should be used to evaluate determine the effectiveness of landslide hazard reduction measures. understood and that the project is likely to • Their inherent limitation in predicting spe- be effective in addressing the causes of the cific landslide locations, timing, and causes problem due to the mismatch between coarse map scales and fine-scale variations in slope 3.2.3 Risks and challenges processes (Keefer and Larsen 2007) Regional policies and local landslide hazards • Their lack of utility in land-use planning for In international development, disaster risk exposure reduction (Opadeyi, Ali, and Chin reduction funding policies are often decided 2005), as high-density unauthorized hous- at a regional level and then translated into ing often already occupies hazardous national programs to address multiple risk slopes. types. This top-down approach typically Holistic awareness of slope processes leads to the production of wide-area qualita- tive maps of landslide susceptibility that Several interrelated factors can affect the sta- practitioners in developing countries may bility of a slope at a variety of spatial and tem- find difficult to apply (Zaitchik and van Es poral scales. These factors should be investi- 2003). There are two possible reasons for the gated at the relevant scale using either a lack of uptake of such maps (Holcombe and qualitative or quantitative (modeling) Anderson 2010): approach or a mixture of both. Direct mea- 8 4    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D surement of all slope parameters is not always ect in terms of funding constraints, geographi- possible; however, engineers or scientists will cal extent, policy context, and type of landslide be able to make an expert judgment of the hazard to be mitigated. dominant causes of the landslide hazard based Correctly identifying the type of landslide on their knowledge of the principles govern- hazard affecting a particular area is vital. Dif- ing slope stability. ferent landslide types have very different physical mechanisms and consequences. Each 3.2.4 Adapting the chapter blueprint to type therefore requires a different hazard existing capacity assessment approach and set of mitigation This chapter provides an introduction to land- measures. This section presents a simple clas- slide processes and the various factors that can sification of landslide types and identifies affect slope stability. It identifies the main those that may be mitigated by a MoSSaiC forms of landslide hazard assessment appro- project—namely, rotational and translational priate at different spatial scales and for various rainfall-triggered slides in weathered slope levels of data and expertise. materials affecting multiple households or Members of the MCU and task teams entire urban communities. should understand basic slope stability pro- MCU and task teams should use this sec- cesses in order to configure the landslide haz- tion to identify the dominant landslide haz- ard reduction measures appropriately and ards in the project area in terms of share this knowledge with community resi- dents and other stakeholders. The MCU and • types of movement and material involved, government task teams should have at least • geometry, one civil, environmental, or geotechnical engi- • triggering mechanism, and neer, or an expert in physical, geotechnical, or • slope stability over time. hydrological sciences, who can lead the land- slide hazard assessment process. The project 3.3.1 Types of slope movement and should be scientifically justified and that justi- landslide material fication understood by all involved. Although many types of mass movements are The MCU should begin by assessing avail- referred to as landslides, the technical use of able capacity in this area. Use the matrix on the term applies only to mass movements the next page to help make that assessment. where there is a distinct zone of weakness that 1. Assign a capacity score from 1 to 3 (low to separates the slide material from more stable high) to reflect existing capacity for each underlying material. For a helpful, well-illus- element in the matrix’s left-hand column. trated guide to different landslide types and geometries, see USGS (2004). 2. Identify the most common capacity score as Varnes (1978) classified five principle types an indicator of the overall capacity level. of mass movement in three types of slope 3. Adapt the blueprint in this chapter in accor- material (table 3.2). As highlighted in the table, dance with the overall capacity level (see MoSSaiC is designed to address rotational and guide on the bottom of next page). translational slides in predominately weath- ered materials (unconsolidated fine soils) that are principally triggered by rainfall. 3.3 LANDSLIDE TYPES AND • Rotational slide. The surface of rupture is THOSE ADDRESSED BY curved concavely upward, and slide move- MOSSAIC ment is roughly rotational (figure 3.1a). The first step in the landslide risk manage- • Translational slide. The landslide mass ment process is to define the scope of the proj- moves along a roughly planar surface with CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    8 5 EXISTING CAPACITY CAPACITY ELEMENT 1 = LOW 2 = MODERATE 3 = HIGH MCU member(s) familiar with No major education in Some MCU members have a Two or more MCU members landslide processes and hazard landslide processes or basic grounding in landslide have sound education in reduction measures previous experience with processes or some experience landslide processes and landslide hazard reduction with landslide hazard experience in implementing projects reduction projects landslide hazard reduction projects Training available on landslide No local provision for training Courses on some aspects of Training courses on both processes and hazard landslide processes and hazard landslide processes and hazard reduction reduction locally available reduction locally available Availability of slope stability No slope stability analysis Either slope stability analysis Slope stability analysis analysis software and software or expertise available software or expertise available software and expertise expertise to government, but not both available within government and used on projects Government capacity to Limited government capacity One-off landslide mitigation Government department support landslide mitigation to support and implement projects previously under- routinely handles landslide (hazard reduction) projects landslide mitigation projects taken by government mitigation work Project safeguards Documented safeguards need Documents exist for some Documented safeguards to be located; no previous safeguards available from all relevant experience in interpreting and agencies operating safeguard policies CAPACITY LEVEL HOW TO ADAPT THE BLUEPRINT 1: Use this chapter The MCU needs to strengthen its capacity in understanding landslide processes and using relevant in depth and as a analytical software. This might involve the following: catalyst to secure • Working with local commercial or higher education partners to share and learn from their experience in support from other slope stability analysis agencies as appropriate • Searching for colleagues in government with relevant slope stability experience and considering their appointment to the MCU • Approaching suitable materials laboratories and consultants for data on soil material properties 2: Some elements The MCU has strength in some areas, but not all. Elements that are perceived to be Level 1 need to be of this chapter will addressed as above. Elements that are Level 2 will need to be strengthened, such as the following: reflect current • Where there is no slope stability analysis software, seek training on the use and application of such practice; read the software remaining elements in depth and use • Where there is limited existing government coordination of landslide hazard assessment, pool the them to further relevant expertise and data from different ministries and agencies strengthen capacity • Where there is limited or incomplete understanding of landslide causes, provide a technical briefing session for nonexperts based on material in this chapter 3: Use this chapter The MCU is likely to be able to proceed using existing proven capacity. The following would nonetheless as a checklist be good practice: • Document relevant prior experience in landslide hazard assessment and related safeguard documents • Endorse such a document at an MCU meeting prior to commencement of works 8 6    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D TAB L E 3 .2  Slope instability classification TYPE OF MATERIAL UNCONSOLIDATED SOIL TYPE OF MOVEMENT BEDROCK Coarse Fine Falls Rock fall Debris fall Earth fall Topples Rock topple Debris topple Earth topple Rotational Rock slide Debris slide Earth slide—the landslide type Slides relevant to MoSSaiC Translational Flows Rock flow Debris flow Earth flow Complex Combination of two or more types Source: Cruden and Varnes 1996. © National Academy of Sciences, Washington, DC, 1996. Reproduced with permission of the Transportation Research Board. Note: The types of slope movement and associated material that are addressed by MoSSaiC are highlighted. little rotation or backward tilting (fig- fied and plotted (in accordance with fig- ure  3.1b). A block slide is a translational ure 3.2). slide in which the moving mass consists of a The scale of landslides in vulnerable com- single unit or a few closely related units that munities in the tropics will generally be deter- move downslope as a relatively coherent mined by soil depth, since the slip surface is mass. often at the interface between the soil and the 3.3.2 Landslide geometry and features bedrock (or at a marked change of soil weath- ering grade). Typical depths to the slip surface Different types of landslide can be recognized may be in the range 1–10 m. by their geometry and features (figure  3.2). The lateral extent of landslides in such The idealized forms shown in figures 3.1 and locations is often controlled by topographic 3.2 are not always easy to identify in the field if features such as zones of drainage conver- vegetation cover obscures the landslide or if gence and deeper soils. Where more localized the landslide is old. Only comparatively recent factors are acting to destabilize the slope, the landslides are likely to exhibit an identifiable landslide may be less extensive. Typical maxi- failure zone at the head of the moved mass. mum widths of the main body of the landslides When mapping landslide locations, as many (figure 3.2, feature 6) may be in the range of these features as possible should be identi- 10–50 m or more. Rotational landslides in soils are not as mobile as some other forms of landslide (such FI G U R E 3 .1  Characteristics of rotational as debris slides). Typically, the surface of sepa- and translational slides in predominantly ration of rotational landslides (figure 3.2, fea- weathered materials ture 12) may be in the range of a few meters to a. Rotational slide b. Translational slide about 100 m, depending on the volume of material involved and the slope angle. 3.3.3 Landslide triggering events: Rainfall and earthquakes Every slope has stabilizing and destabilizing forces. The different preparatory and aggra- vating factors that determine the relative sus- Source: USGS 2004; reproduced with permission. ceptibility of a slope to landslides are detailed in section 3.4. A slope that is relatively suscep- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    8 7 FI G U R E 3 .2  Definitional features of a landslide 1. Crown: The undisplaced material adjacent to the highest parts of the main scarp. 2. Main scarp: A steep surface on the undisturbed ground at the upper edge of the 14 landslide, caused by movement of the displaced material away from the undisturbed A ground; the visible part of the surface of rupture. 16 5 3. Top: The highest point of contact between the displaced material and the main scarp. 20 4. Head: The upper parts of the landslide along the contact between the displaced 15 material and the main scarp. 5. Minor scarp: A steep surface on the displaced material of the landslide produced by 18 differential movements in the displaced material. 10 B 6. Main body: The part of the displaced material of the landslide that overlies the surface 12 of rupture between the main scarp and the toe of the surface of rupture. 7. Foot: The portion of the landslide that has moved beyond the toe of the surface of rupture and overlies the original ground surface. 19 8. Tip: The point of the toe farthest from the top of the landslide. 1 9. Toe: The lower, usually curved, margin of the displaced material of a landslide; it is the most distant from the main scarp. 10. Surface of rupture: The surface that forms the lower boundary of the displaced A 3 4 6 11 7 8 B material below the original ground surface. 11. Toe of the surface of rupture: The intersection (usually buried) between the lower 9 part of the surface of rupture of a landslide and the original ground surface. 2 12. Surface of separation: The part of the original ground surface overlaid by the foot of the landslide. 19 13. Displaced material: Material displaced from its original position on the slope by move- original ground level ment in the landslide. It forms both the depleted mass and the accumulation. extent of displaced material 14. Zone of depletion: The area of the landslide within which the displaced material lies below the original ground surface. undisturbed ground 15. Zone of accumulation: The area of the landslide within which the displaced material lies above the original ground surface. 16. Depletion: The volume bounded by the main scarp, the depleted mass, and the original ground surface. 17. Depleted mass: The volume of the displaced material that overlies the rupture surface but underlies the original ground surface. 18. Accumulation: The volume of the displaced material that lies above the original ground surface. 19. Flank: The undisplaced material adjacent to the sides of the rupture surface. Compass directions are preferable in describing the flanks but if left and right are used, they refer to the flanks as viewed from the crown. 20. Original ground surface: The surface of the slope that existed before the landslide took place. Source: International Geotechnical Societies UNESCO Working Party on World Landslide Inventory 1993. tible to landslides may exist in a state of mar- Lumb 1975). MoSSaiC is specifically targeted ginal stability for a long period until a particu- to address this form of landslide hazard lar event decreases the stabilizing forces and/ through the construction of a network of sur- or increases the destabilizing forces, triggering face water drains. a landslide. The most common landslide trig- Rainfall, slope hydrology, and landslides gers are rainfall events and seismic events (earthquakes). Because these triggers act on a Rainfall-triggered landslides occur in most slope in different ways, it is important to dis- mountainous landscapes and can have an tinguish between those landslides that are enormous effect on the landscape, properties, rainfall triggered versus those that are seismi- and people. Intense or prolonged rainfall cally triggered so that appropriate risk mitiga- infiltrates the slope surface, causing an tion measures can be identified. increase in soil pore water pressure and an The majority of landslides in the humid associated lowering of slope material tropics are triggered by rainfall (Crosta 2004; strength. The forces that act to stabilize the 8 8    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D slope are thus reduced, and the slope fails along the zone where the destabilizing forces F IGUR E 3 . 3  Typical surface and subsurface water sources and flow paths associated with unauthorized construction on hillslopes (gravity and loading) overcome the stabiliz- ing forces. rainfall Urban development can alter the prepara- tory factors affecting slope stability, changing surface water slope geometry, loading, surface cover, and runo and infiltration slope hydrology. Significantly, urban develop- water from roofs ment can increase the effectiveness of rainfall with no guttering or drain connection in triggering landslides by changing natural drainage routes, concentrating surface water flows, changing surface vegetation cover (which would normally intercept and store groundwater rainfall and remove water from the soil), badly drained broken, blocked, roads and paths increasing rainfall runoff from impermeable or unlined drains surfaces, and increasing surface water infiltra- piped water from households tion in other areas (figure 3.3). The most vul- and septic tanks/pit latrines nerable communities in developing countries will probably not have sufficient surface water drainage, but may have publicly supplied piped Seismic events water, which further increases the amount of water on the slope. Rainfall-triggered land- Seismic activity can also affect the forces act- slide hazard is thus often increased by urban- ing on a slope and trigger landslides. Cur- ization. rently, MoSSaiC does not address the land- As noted, in humid tropical developing slide mechanisms associated with this countries, the majority of fatalities and physi- triggering process. Nevertheless, the MCU cal losses occur in urban areas (Petley 2009). should have some familiarity with seismic At the local scale, even small landslide events risk where it coexists with the potential for in densely populated areas can result in sig- rainfall-triggered landslides. In such cases, a nificant loss of life and property and stall eco- holistic approach to disaster risk reduction nomic development. Houses may be lost or should be taken if possible. For example, the made unsafe, and community infrastructure MoSSaiC approach to community-scale slope destroyed (figures 3.4a and b). Multiple land- drainage networks, plus the house-by-house slides may be widespread throughout the area installation of roof guttering and gray water (figure 3.4c). connections to the drains, could be coupled Shallow and deep-seated landslides alike with guidelines on earthquake-resilient prop- can be triggered by rainfall. Records of land- erty design for such communities (Build slides and associated rainfall triggers (charac- Change 2011). terized by intensity, duration, and frequency) Globally, many locations have oversteep- can be used to predict the timing of future ened and highly weathered hillsides, where rainfall-triggered landslide events. Extensive large landslides could cause significant harm research has been conducted to identify both to local communities—many of which are landslide-prone terrains (Hansen 1984; already vulnerable in terms of housing struc- Soeters and van Westen 1996) and the rainfall tures and poverty. The 2001 earthquakes in El intensities and durations that cause slopes to Salvador (figure 3.5) are a notable example in fail (Larsen and Simon 1993). These two issues this regard, causing over 600 landslides and are discussed further in section 3.4; De Vita et resulting in many hundreds of fatalities, with al. (1997) provide an extensive bibliography on 585 deaths in the community of Las Colinas rainfall-triggered landslides. alone (figure 3.6). CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    8 9 Empirical evidence linking seismic activ- FI G U R E 3 .4  Rotational and translational landslides ity; preparatory factors such as slope angle, geology, and soils; and landslide events can be formalized by measures of seismic intensity. An instrument-based measure of seismic intensity developed by Arias (1970) was first used for analyzing the occurrence of land- slides by Wilson and Keefer (1985), and its use has become relatively widespread for that purpose since. The Arias intensity, for any given strong-motion recording, is expressed as Ia = π/2g ∫0Td [a(t)2]dt Where: a. Rotational slide in St. Lucia triggered by rainfall during Hurricane Dean Ia = Arias intensity in units of velocity (2007) caused the loss of three houses. t = time a(t) = ground acceleration as a function of time Td = total duration of the strong-motion record g = acceleration due to gravity Arias intensity is a ground motion parame- ter that captures the potential destructiveness of an earthquake as the integral of the square of the acceleration-time history. It correlates well with several commonly used demand measures of structural performance, liquefac- tion, and seismic slope stability (Travasarou, Bray, and Abrahamson 2003). Based on theo- retical considerations, statistical analysis of strong-motion attenuation, and empirical data b. Translational slide in St. Lucia triggered by ~500 mm of rainfall in 24 on landslide limits in historical earthquakes, hours associated with Hurricane Tomas (2010); slide caused the loss of a the Arias intensity thresholds can be related to road (center) and significantly damaged houses at the landslide crest. types of landslide (table 3.3) (Keefer 2002; Keefer and Wilson 1989; Wilson and Keefer 1985). Keefer (2002, 504) notes that while earth- quake-induced landslides have been docu- mented for more than 3,700 years, it is clear that more seismic data are needed: …the number of earthquakes with relatively complete data on landslide occurrence is still small, and one of the most pressing research needs is for complete landslide inventories for many more events in a wider variety of environments. c. Hillside-wide translational landslides St. Lucia triggered by Hurricane Tomas. These empirical data, when coupled with analytical tools such as geographic informa- 9 0    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D FI G U R E 3 .5  Distribution of seismicity during the 2001 El Salvador earthquakes 14°0'N earthquake depth (m) 13°0'N  0–20  21–50  > 50 90°0’W 89°0’W 88°0’W Source: Garcia-Rodriguez et al. 2008. Note: Data were recorded and relocated by the Salvadoran Short-Period Network of the Center for Geotechnical Investigations. Shown are the main earthquakes on January 13, February 13, and February 17, 2001, and their aftershocks. The January 13 earthquake, which triggered over 600 landslides including in Las Colinas, was located in the subduction zone between the Cocos and Caribbean plates, with a magnitude of 7.7 (moment magnitude) and a focal depth of 40 km. FI G U R E 3 .6  Aerial view of earthquake- TAB LE 3 . 3  Arias intensity and associated landslide categories triggered landslide in Las Colinas, El Salvador, ARIAS INTENSITY VALUE RESULTANT LANDSLIDE January 13, 2001 THRESHOLD CATEGORY 0.11 ms−1 Disrupted landslides 0.32 ms−1 Coherent slides, lateral spreads, and flows 0.54 ms−1 Lateral spreads and flows Source: Keefer and Wilson 1989. shows the landslide velocity scale proposed by Cruden and Varnes (1996). Source: Garcia-Rodriguez et al. 2008. In the tropics, rainfall-triggered landslide movement typically lasts anywhere from a few minutes to a few hours. Progressive slides and tion systems (GIS), could lead to substantial subsequent slope settlement can continue additional refinements in physically based over periods as long as a year or more. Fig- models that relate seismic shaking and geo- ure  3.7 shows a rotational landslide periodi- logic conditions to slope failure. cally moving over five years, causing increased damage to the property. 3.3.4 Slope stability over time The magnitude of a landslide will deter- Landslide velocities can vary significantly mine the damage caused to people and prop- depending on type, material, trigger, and a erty. Landslide magnitude is defined by the range of other slope properties. Table 3.4 velocity of the slide and the size of the area CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    9 1 TAB L E 3 .4  Landslide velocity scale VELOCITY VELOCITY TYPICAL CLASS DESCRIPTION (mm/s) VELOCITY PROBABLE DESTRUCTIVE SIGNIFICANCE Catastrophe of major violence; buildings destroyed by impact of 7 Extremely rapid displaced material; many deaths; escape unlikely 5 × 103 5 m/s 6 Very rapid Some lives lost; velocity too great to permit all persons to escape 5 × 10 1 3 m/min Escape evacuation possible; structures, possessions, and equipment 5 Rapid destroyed 5 × 101 1.8 m/h Some temporary and insensitive structures can be temporarily 4 Moderate maintained 5 × 103 13 m/month Remedial construction can be undertaken during movement; insensi- 3 Slow tive structures can be maintained with frequent maintenance work if total movement is not large during a particular acceleration phase 5 × 105 1.6 m/year 2 Very slow Some permanent structures undamaged by movement 5 × 10 7 15 mm/year Imperceptible without instruments; construction possible with Extremely slow precautions Source: Cruden and Varnes 1996. © National Academy of Sciences, Washington, DC, 1996. Reproduced with permission of the Transportation Research Board. FI G U R E 3 .7  Progressive landslide a. In 2005, rainfall triggered a progressive b. The same house in 2008 shows the c. The same house in 2010 shows the rotational landslide in a vulnerable slow progressive movement of the structure’s near collapse after five years community in St. Lucia. rotational failure. of very slow progressive slope failure. affected, in terms of both the actual failed area (reduction in hazard) or a decrease in stability and the travel distance of the displaced mate- due to the slide’s creating an unstable scarp rial (the accumulation zone). (figure 3.8). The slope’s postfailure stability can also In an area of existing landslides, postfailure contribute to overall landslide impact. stability should be carefully assessed to iden- Depending on the geometry of the slide and tify possible future hazard, since this may be the resulting geometry of the slope, there may either increased or decreased by occurrence of be either a relative increase in overall stability a slope failure. 92    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D • Section 3.5 describes how each of the slope FI G U R E 3 .8  Postfailure slope stability stability variables can be identified, mea- sured, and interpreted in the field. • Section 3.6 details the physically based slope stability assessment methods that are particularly relevant to MoSSaiC. 3.4.1 Landslide preparatory factors and triggering mechanisms The factors that determine the stability of a slope can be categorized as a. Landslide caused by soil water convergence at, and immediately above, the zone of failure, • preparatory factors, determining the sta- the impact of which serves to reduce subse- bility of a slope over a period of time, quent landslide risk since the local slope angle has been reduced as a consequence of the • triggering mechanisms, the dynamic events failure. that result in a landslide, and • aggravating factors, the many human activities that can reduce the stability of a slope without necessarily triggering a land- slide (table 3.5). These various factors will act and interact across a particular slope to determine its sta- bility state at any point in time. Each factor must be taken into account and their com- bined influence assessed in order to under- stand the stability of a slope. Factors that cause landslides are often quite localized in nature. Extensive work in Hong Kong SAR, China, has demonstrated that, for a large number of landslides, the main rainfall trigger works in conjunction with highly specific local preparatory factors (GCO b. Landslide below unauthorized houses triggered by the discharge of upslope water, 1984). Table 3.6 provides a summary of the causing oversteepening at the crest of the range of scales over which the different pre- landslide, and subsequent increase in landslide paratory and triggering factors could be hazard. expected to operate. To deliver landslide haz- ard reduction measures at the community scale (the MoSSaiC objective), the relevant 3.4 SLOPE STABILITY PROCESSES slope processes must be assessed at the 1–100 AND THEIR ASSESSMENT m scale. This section introduces the different factors 3.4.2 Overview of slope stability and variables that can determine the stability assessment methods of a slope and some of the main methods for In discussing the methods and outputs of an assessing slope stability. More information on assessment of slope stability, it is necessary to slope stability processes and assessment is understand the difference between landslide provided in the following two sections: susceptibility and landslide hazard: CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   93 TAB L E 3 .5  Factors determining slope stability and associated assessment methods FACTOR DETERMINING SLOPE STABILITY Preparatory Aggravating ASSESSMENT METHOD Slope angle Construction—oversteepening of slopes GIS, maps, survey, Abney level Slope hydrology Poor or altered slope drainage—leaking • Topographic convergence from maps/ or incomplete drains; blocked drains and survey natural channels; saturated soils; water • Water table from piezometer records from house roofs, kitchens, and bathrooms • Detailed on-site drainage survey Slope material depth, structure, and type Poorly compacted fill or previously failed Material grades, shear box direct material measurement Vegetation Change or removal of vegetation due to Field observation cultivation or construction Loading Overloading—dense, unplanned housing, Survey of housing density and construc- water tanks, or infrastructure tion material Previous landslides Ongoing or progressive movement of Survey and records of known failures slope DYNAMIC TRIGGERING MECHANISMS Rainfall events (e.g., storms, hurricanes, prolonged periods of rainfall) Rainfall data and frequency analysis Seismic events (not currently incorporated in MoSSaiC methodology) Seismograph data and frequency analysis TA BLE 3. 6  Spatial scales of landslide triggering mechanisms, preparatory factors and anthropogenic influences SPATIAL SCALE OVER WHICH VARIATION OCCURS Local/household Hillside Region MECHANISM/FACTOR/INFLUENCE 1m 10 m 100 m 1,000 m 100 km Triggering mechanisms Rainfall Seismic activity Preparatory factors Slope geometry Soils and geology Slope hydrology Vegetation Anthropogenic (aggravating) influences Surface water Groundwater level Slope angle (cut) Load (building) Vegetation Source: Holcombe and Anderson 2010. 9 4    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D • Landslide susceptibility relates to the type slope instability and for confirmation of the and spatial distribution of existing or poten- type of landslide hazard tial landslides in an area. Susceptibility • Empirical rainfall threshold modeling—if assessment is based on the qualitative or sufficient empirical data are available, this quantitative assessment of the role of pre- method can be used in conjunction with paratory factors in determining the rela- susceptibility maps to indicate the potential tive stability of different slopes or zones. timing and spatial distribution of multiple The magnitude and velocity of existing or landslide events potential landslides may be taken into account, but the frequency or timing will • Physically based slope stability modeling— not be specified. the most relevant approach for MoSSaiC, as it allows investigation of the slope stability • Landslide hazard is the probability of a processes and landslide trigger at a scale landslide (qualitatively or quantitatively enabling the identification of appropriate assessed) of a certain type, magnitude, and hazard reduction measures (1–100 m2). velocity occurring at a specific location. Quantitative hazard assessment takes into 3.4.3 GIS-based landslide susceptibility account the role of the triggering event (of mapping a known probability) causing the landslide. Many wide-area and spatially distributed Several different approaches can be used to landslide assessments use GIS software as the assess landslide susceptibility and hazard, platform for assembling digital maps of prepa- including direct geomorphologic mapping, ratory variables such as topography, soils and index-based mapping and heuristic (expert) geology, drainage patterns, and land use. The assessment, inventory-based empirical and data can be augmented and the analysis statistical modeling of slope parameters, and extended if there is a record of the locations of deterministic (physically based) and probabi- past landslides. Landslide inventories allow listic modeling of slope processes (Aleotti and the identification of precedents in which the Chowdhury 1999; Dai, Lee, and Ngai 2002; and influence of each preparatory variable is deter- Huabin et al. 2005; these also contain summa- mined with respect to slope stability and ries of these methods). Table 3.7 outlines the assigned a weighting. Alternatively, experts respective advantages and disadvantages of may assign weights based on their judgment the principal approaches. and experience. The resulting index overlay Selection of the most suitable approach for maps define the landslide susceptibility for a given study must consider the spatial scale each terrain unit. On their own, these GIS- for which it is most appropriate, the data based susceptibility maps cannot be used to requirements, and the level of quantification it predict the exact timing and location of indi- affords (van Westen et al. 2006; van Westen et vidual landslides, but they do provide a vital al. 2008). Four methods of relevance to tool for planning and management in terms of MoSSaiC are briefly reviewed in sections broad zones of relative landslide susceptibility. 3.4.3–3.4.6: An example of GIS capability for develop- ing landslide susceptibility maps is given by • Spatially distributed landslide susceptibil- Nandi and Shakoor (2010). They developed ity mapping using GIS-based methods— relationships between landslides and various useful for the initial identification and pri- instability factors contributing to their occur- oritization of areas with relatively high rence using GIS. A landslide inventory map landslide susceptibility (as described in was prepared using landslide locations identi- chapter 4) fied from aerial photographs, field checks, and • Direct landslide hazard mapping—also use- existing literature. Seven instability factors ful for identification of areas of existing were then selected—slope angle, soil type, soil CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    9 5 TAB L E 3 .7  Advantages and disadvantages of different forms of landslide susceptibility and hazard assessment SCALE METHOD ADVANTAGE DISADVANTAGE S M L Field • Allow rapid assessment taking into account • Totally subjective methodology R Y Y geomorphologic a large number of factors • Use of implicit rules that hinder critical analyses analysis of results Combination of • Solve the problem of hidden rules • Subjectivity in attributing weighted values R Y Y index maps • Total automation of steps to single classes of each parameter • Standardization of data management Logical analytical • Allow the comparison of different slopes • Require monitoring data, preferably from R R Y models • Mathematically rigorous and perfectible installed instruments applicable mainly to slow-speed landslides Statistical • Objective methodology • Systematic collection and analysis of data Y Y R analyses (bivariate • Total automation of steps concerning different factors is quite and multivariate) cumbersome • Standardization of data management Safety factor- • Objective scope and methodology • Need for detailed knowledge of the area R R Y deterministic • Quantitative scope • Use of appropriate geotechnical model approaches requires a lot of experience • Encourages investigation and measurement of geotechnical parameters in detail • Does not take various uncertainties into account Probabilistic • Allow consideration of different uncertain- • Require comprehensive data, otherwise Y R R approaches ties subjective probabilities required • Quantitative scope • Probability distributions difficult especially • Objective scope and methodology for low level of hazard and risk • Provide new insight not possible in deterministic methods Neural networks • Objective methodology • Difficult to verify results when instrumen- R Y Y • Do not require theoretical knowledge of tal data are not available physical aspects of the problem Source: Aleotti and Chowdhury 1999. Note: S = small; M = medium; L = large; R = restricted use; Y = yes. erodibility, soil liquidity index, land cover pat- watershed, the results from the training area tern, precipitation, and proximity to stream— could be extrapolated using the regression that were considered to be of significance in model. This process yielded a landslide sus- terms of landslide occurrence. These were ceptibility map (figure 3.10). imported into the GIS as raster data layers and Basic regression methods for landslide sus- ranked using a numerical scale corresponding ceptibility assessment can be refined by com- to the physical conditions of the region. Fig- puting weight-based combinations of signifi- ure  3.9 illustrates the spatial data for four of cant factors and excluding insignificant factors the presumed independent controlling vari- from consideration; GIS mapping of this type ables. has been widely researched (Lee 2005; Regression analysis was used to associate Nefeslioglu, Gokceoglu, and Sonmez 2008; the occurrence of known landslides with the Van Den Eeckhaut et al. 2006; Van Westen independent slope variables in a subarea of the 2004). watershed (a process known as model train- A GIS environment can also be used as the ing). By assuming that similar slope instabil- platform for simplified deterministic model- ity–related conditions existed in the entire ing of landslide hazard zones or coupling with 9 6    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D FI G U R E 3 .9  Classified spatial factor data a. Slope angle b. Streams c. Soil type d. Land cover Source: Nandi and Shakoor 2010. rainfall forecasts. This form of modeling cal landslides—the relevant features of which requires accurate and detailed spatially dis- might be masked by subsequent land-use tributed data on slope parameters and a high change. level of expertise. Even at the hillside and community scales, direct landslide hazard mapping can be prone 3.4.4 Direct landslide mapping to significant error. Ardizzoni et al. (2002) out- On-the-ground mapping of existing landslides line the potential extent of such errors by com- in areas of known slope instability produces paring hazard mapping results from three maps that can potentially be used for land-use independent mapping teams in a landslide- planning, informing landslide risk manage- prone area of Italy. They found large differ- ment strategies, and creating landslide inven- ences between the landslide hazard maps in tories that can be included in GIS-based land- the form of positional errors (55–65 percent); slide hazard analyses. An experienced these increased significantly when all three mapping team can plot both visible landslide maps were overlaid (~85 percent spatial mis- features and the possible locations of histori- match). Figure 3.11 illustrates the differences CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    9 7 in the teams’ interpretations of the location of F IG U R E 3.1 0  Landslide susceptibility map existing landslides. Information is lacking regarding the uncer- tainties associated with landslide inventory maps (Gallie et al. 2008). Rather than only mapping existing landslides, studies suggest that it may be appropriate for expert mapping teams to identify the topography and other preparatory factors likely to be associated with both existing and future slope failure. In this way, direct mapping of slope features could be Logistic regression used to inform the design of landslide mitiga- susceptibility rating low susceptibility tion measures to address the potential land- medium susceptibility slide causes. high susceptibility very high susceptibility 3.4.5 Empirical rainfall threshold landslide locations in test area modeling Source: Nandi and Shakoor 2010. Historical data on landslides and associated Note: The landslides of the test area are overlaid on the map. rainfall events can be used to establish land- slide probability based on the probability of the triggering rainfall. With sufficient data, the critical rainfall characteristics required to trig- F IG U R E 3.1 1  Three landslide inventory ger landslides can be established for a particu- maps lar region. This is referred to as threshold analysis, and it can be used to predict the Milano landslide expected number of landslides for a particular inventory rainfall forecast. Although this is a useful plan- ning tool, it cannot be used on its own to iden- tify the landslide hazard affecting a specific slope. There are a number of forms that empirical Perugia landslide threshold equations can take depending on the inventory rainfall parameters selected (IRPI 2012). A common form is an intensity-duration equa- tion, which is derived by plotting rainfall intensity (I) against rainfall duration (D) and identifying the threshold above which land- Pavia slides will be triggered. I-D thresholds have landslide the general form inventory  village I = c + α D−ß  road  landslide Where: Source: Ardizzoni et al. 2002. I = Rainfall intensity Note: Maps were surveyed by three independent D = Rainfall duration teams in the Apennines, Italy. Mapped area comprises c ≥ 0 hillside surrounding three small villages. Overall errors in positional mismatch approximately 85 percent. α > 0 ß > 0 9 8    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D Commonly, intensity lies between 1 and 100 mm s−1, duration between 1 and 200 hours, F IGUR E 3 .12  Global rainfall intensity-duration thresholds ß between 2.00 and 0.19, and c = 0 (Guzzetti et intensity (mm/hour) al. 2007; figure 3.12). When c = 0, the threshold 100 7-day threshold 3-day threshold relationship is a simple power law. This nega- 1-day threshold tive power law holds for four orders of magni- tude of rainfall duration (up to durations of 10 500 hours), suggesting a self-similar scaling behavior of the rainfall that triggers landslides (Guzzetti et al. 2007). B A 1 Specific rainfall intensity-duration thresh- C old relationships should be calculated for indi- D vidual regions or countries. For example, for E 0.1 Puerto Rico, I = 91.46D−0.82 (Larsen and Simon 0.1 1 10 100 1,000 1993). duration (hour) Source: Kirschbaum et al. 2009. 3.4.6 Physically based slope stability Note: A = Caine 1980; B = Hong, Adler, and Huffman 2006; C = Crosta and Frattini modeling 2001; D = Innes 1983; E = Guzzetti et al. 2008. To determine the landslide hazard affecting a specific slope, the preparatory and triggering • Numerical models that couple dynamic mechanisms unique to that slope need to be hydrology with limit equilibrium analysis taken into account. This can be undertaken by experts directly mapping slope features in the • Numerical models that represent slope field (heuristic approach; see section 3.4.4). material in terms of its stress-strain behav- Conversely, a quantitative analytical or numer- ior (continuum models) or as particles (dis- ical modeling approach can be applied in crete element models) which geotechnical equations are used to rep- Analytical methods for determining factor of resent landslide processes. safety Many such quantitative approaches express slope stability in terms of its factor of safety (F) which is the ratio between the total Static limit equilibrium methods (analytical or available shear strength of the slope (resisting lumped mass approaches) evaluate the stabi- lizing and destabilizing forces affecting a mass forces) and the shear stresses (destabilizing of material on an observed or assumed poten- forces). tial failure surface (known as the slip surface or shear surface). The slope is analyzed as a F = available shear strength of slope shear stress acting to destabilize slope two-dimensional cross-section, and the mate- rial above the slip surface is typically divided (discretized) into vertical slices. The stabiliz- F = 1 Marginally stable slope ing and destabilizing forces acting at the base F < 1 Unstable slope of each slice (at the slip surface) are calculated F > 1 Stable slope for a single point in time and take into account the angle of the slip surface at the slice base, There are three broad types of physically the weight of the slice material, loading on top based modeling that may be used to determine of the slice (such as buildings or vegetation), slope stability; these are as follows, in order of the effect of pore water pressure, and the shear increasing complexity: strength of the material (cohesion and angle of • Analytical methods for calculating factor of internal friction). F is then calculated for the safety (static limit equilibrium methods) entire slip surface. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    9 9 Different limit equilibrium methods are • Along the slip surface, the material will employed according to the assumed geometry exhibit failure according to the specific cri- of the landslide failure surface: teria selected for representing shear strength (the Mohr-Coulomb criteria for • Single plane (or slightly curved), usually elasto-plastic failure is typically used for shallow translational slides in steep slopes soils). • Circular, uniform strata or deep soils and • At the moment of failure, the shear strength small to medium-size rotational landslides is fully mobilized along the length of the (figure 3.13) slip surface. • Double or triple wedges, medium to large • The water table location (and hence, the translational landslides. pore water pressure field) is static and is Figure 3.13 shows the method of slices defined by the user. (Ordinary and Bishop methods) represented • Different assumptions are made about the on a sample slope in which it is assumed that interslice forces, depending on the method. failure will occur by rotation of a block of soil on a cylindrical slip surface. (See Nash 1987 for • Behavior of the slope material once failure a review of different limit equilibrium meth- has occurred is not accounted for. ods.) Limit equilibrium analysis requires several The results of the factor of safety analysis simplifying assumptions to be made to calcu- are of limited value in themselves, as they late F: depend on the simplifying assumptions of the method adopted, the parameter values • A slope will fail as a coherent mass of mate- selected, the water table location, slip surface rial sliding along a specific two-dimen- geometry and location, and the discretization sional slip surface defined by the user of the slope. For example, in figure 3.13, the (stress-strain relationships and three- Bishop method gives an F of 1.52, while the dimensional effects involved in the mechan- Ordinary method of slices gives an F of 1.43. ics of failure are not represented). Note that a factor of safety of 1 does not neces- sarily indicate that failure of the slope is immi- nent. Moreover, the real factor of safety is FI G U R E 3 .13  Discretization of a slope into slices to facilitate slope influenced by many variables that are not nec- stability calculations essarily represented in the slope stability F = 1.43 calculated slice weight w = b ∑ (γi hi) model, such as minor geological or soil details, using the Ordinary and progressive failure of the slope, among c = 4.8 kN/m2 method of slices trial slip circle many others (Nash 1987). Φ = 35 degrees Soil 1 h1 F = 1.52 calculated γ = 17.3 kN/m2 using Bishop’s c = 35.9 kN/m2 Dynamic slope hydrology and limit equilibrium Soil 2 h2 models modified method Φ = 0 degrees γ = 17.3 kN/m2 The second type of slope stability model sig- nificantly advances the static analysis methods 10 m by dynamically integrating external “forcing” scale silty variables (landslide triggering factors) such as sand rainfall and slope hydrology, so that slope sta- clay bility can be analyzed over a period of time. firm soil Although there are fewer commercially avail- able integrated dynamic hydrology and limit Source: Turner and Schuster 1996; © National Academy of Sciences, Washington, DC, 1966. Reproduced with permission of the Transportation Research Board. equilibrium models than static limit equilib- rium models, they are an improvement over 1 0 0    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D the classic limit equilibrium method in the fol- scale from blocks to grains) using a force- lowing ways: based approach. Although some of these models are com- • Groundwater conditions are dynamically mercially available, their data requirements, modeled over time in terms of saturated model sensitivity, and complexity can pose sig- and unsaturated flow, positive and negative nificant challenges to their application. pore water pressures, and rainfall. These dynamic processes are particularly influen- tial in deep tropical residual soils. 3.5 SLOPE STABILITY VARIABLES • Limit equilibrium methods, such as Bishop and Janbu for circular or noncircular fail- This section provides a more detailed descrip- ure, are applied using a search method to tion of the main slope stability variables intro- identify the minimum F surface at specific duced in section 3.4.1—preparatory factors, times during the dynamic hydrology simu- triggering mechanisms, and anthropogenic lations. (aggravating) factors—in terms of their identi- fication and measurement, and their influence Some limitations of dynamic hydrology on slope stability. This information is the basis models relate to the simplifying assumptions for the process of community-based slope fea- used in the calculation of groundwater flow, ture mapping, landslide hazard assessment, which means that these models cannot repre- and design of landslide hazard reduction mea- sent soils with complex or highly spatially sures detailed in chapters 5 and 6. variable flow patterns. Limitations in the sta- Different slope variables may contribute to bility component are related to those inherent the shear strength of the slope (stabilizing in limit equilibrium analysis. forces) or to the shear stresses acting on the The value of this type of dynamic slope sta- slope (destabilizing forces). Some variables bility model is that it allows slope processes may contribute to both shear strength and dominating the stability of a particular slope to shear stress. The way in which each variable be explored. operates can be complex and may change over time with natural processes (such as hydro- Continuum and discrete element models logical variations) or human activities. For Continuum models use distinct rheological example, figure 3.14 shows preparatory factors formulas known as constitutive equations to that could have potential roles in slope insta- describe the behavior of a particular soil type bility, illustrating a variety of subsurface routes under dynamic stress and strain conditions. infiltrating surface water may take. Differ- Therefore, in these models, the shear zone ences in soil water flow paths can lead to “evolves” (rather than being artificially delayed or rapid slope instability responses to imposed in terms of geometry or location) rainfall. according to the geometry of the slope, the ini- The role of these variables in affecting slope tial conditions applied, and the particular rhe- stability may be assessed qualitatively or mea- ology of the material. sured and used as an input in a quantitative Related to the continuum approach are slope stability assessment. macroscale discontinuous deformation analy- sis models, which allow for the local deforma- 3.5.1 Rainfall events tion of shear zones and the overall slope while Rainfall-triggered landslides are the result of accounting for strong discontinuities and surface water infiltration, increased pore detachment of mesh elements. Conversely, water pressure, and a reduction of the shear distinct (or discrete) element methods repre- strength of the slope material. The particular sent the movement of rigid elements (on a combination of preparatory variables and CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 0 1 F IG U R E 3.1 4  Preparatory factors that can influence slope stability rock cliffs 100% water ingress runoff infiltration to through fractures, rock mass root holes etc. partially clay-infilled joint overland rapid recharge down fault following intermittent water into flow zone (days/weeks) slope movement tension crack drop in velocity causes local perched slow sediment deposition in water dike infiltration and active channel throughflow original precut weathered dike aquitard water table fault original ground rise in main surface water table cut seepage pressures induce spring piping along joints and cutting induces high recharge into saprolite through weak materials, hydraulic gradient and from underlying rock allowing relatively rapid flow internal erosion through system (days) Source: Hencher, Anderson, and Martin 2006. rainfall characteristics will determine which Summary: assessment of rainfall events slopes fail. Not all rainfall events will trigger land- • Rainfall events should be described in slides, and not all slopes will fail as a result of a terms of their intensity (mm/h) or total vol- particular event. The intensity and duration of ume (mm), and their duration (h). the rainfall event will determine its effect on a • Rainfall data may be recorded by manual or specific slope. A short, intense rainfall event automatic rain gauges. may have less impact than a longer-duration, less intense event if the hydraulic conductivity • Government ministries and meteorological of the slope is low. It is the hydraulic conduc- organizations usually collect some form of tivity of the slope that determines how much daily or hourly rainfall data. rain infiltrates and how much is retained as • Satellite and radar data can be interpreted surface runoff. Conversely, prolonged very to determine rainfall intensity. low–intensity rainfall may have little effect on a slope with a high hydraulic conductivity, Records should be obtained for all major since the infiltrated water will be rapidly con- rainfall events, in particular the generally heavy veyed through the subsurface without saturat- rainfalls that are associated with hurricanes, ing the soil. tropical storms, and tropical waves (figure 3.15). 1 02    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D FI G U R E 3 .1 5  Hurricane Tomas over the Eastern Caribbean, 2010 Source: National Oceanic and Atmospheric Administration. 3.5.2 Slope angle • not be precise enough to determine slope angles over small distances. Slope angle is one of the key determinants of slope stability. The greater the slope angle, the greater the shear stresses acting on the slope. Slope angle can be efficiently measured However, the relationship between slope angle with a low-cost instrument such as an Abney and slope stability is not straightforward, since level (figure 3.16a), which consists of a fixed the stabilizing forces (the shear strength of the sighting tube, a movable spirit level connected slope) will be determined by variables such as to a pointing arm, and a protractor scale. The material type and strength, water table height, instrument is held at eye level in order to and the influence of loading and vegetation. “sight” a colleague of the same height either Thus, shallow slopes with deep, weak soils can up- or downslope; alternatively, a ranging pole be less stable than steeper slopes comprised of can be marked at eye height (figure 3.16b). shallower soils or exposed bedrock. Accurate slope angle determination is more When assessing slope angles from existing difficult in communities where there is high topographic maps, the accuracy and precision housing density or dense vegetation (fig- of the contours needs to be taken into account ure 3.17), or where previous landslides (which can result in significant ground disturbance) since the contours may have occurred. In such cases, ensuring that the • be interpolated and therefore inaccurate steepest slope segments have been identified with respect to the actual topography (par- requires particular care. At a later stage in the ticularly areas of slope plan convergence project, a more comprehensive topographic and divergence), and/or survey may be required to confirm slope CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 0 3 angles, distances, and drain gradients (see F IG U R E 3.1 6  An Abney level and its use chapter 6). Summary: assessment of slope angle • Estimating local slope angles from topo- graphic maps is likely to be imprecise. • Use an Abney level, theodolite, total station, or similar instrument to measure slope a. Abney level. angles. • Dense vegetation may mask the true topog- raphy. 3.5.3 Material type and properties Material type plays a significant part in deter- mining which slopes are susceptible to land- slides. In assessing the influence of slope material on stability, three broad characteris- tics need to be determined: • The depth and location (strata) of different material types on the slope • The strength of the materials • The hydrological properties of the materials Soil formation b. Abney level being used to measure slope angle. In the tropics, rock is weathered relatively rap- idly due to the high temperatures and humid- ity; this can result in the formation of deep F IG U R E 3.1 7  Slope benched by resident to soils over weakened bedrock. The first stage in build a house assessing the influence of materials on slope stability is therefore to estimate the approxi- mate depth of soil and weathered material. The MoSSaiC methodology addresses slopes where the dominant surface material is resid- ual soil. Weathering and strength The typical weathering profile of tropical soils is commonly expressed in terms of six weath- ering grades (figures 3.18 and 3.19). Dense vegetation above the benched slope The weathering grade of slope material can and a major failure below the property can be considered a surrogate for strength: gener- make it more difficult to estimate the hillslope ally, the greater the weathering from rock to segment slope angles. soil, the weaker the material. The strength of residual soils can vary greatly depending on its parent material (composition). Soils can be 1 0 4    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D FI G U R E 3 .1 8  Typical weathering profiles of tropical soils Humus/topsoil VI Residual All rock material converted to soil; mass structure and material fabric soil destroyed. Significant change in volume. V Completely All rock material decomposed and/or disintegrated to soil. weathered Original mass structure still largely intact. IV Highly More than 50% of rock material decomposed and/or disintegrated to soil. weathered Fresh/discolored rock present as discontinuous framework or corestones. III Moderately Less than 50% of rock material decomposed and/or disintegrated to soil. weathered Fresh/discolored rock present as continuous framework or corestones. II Slightly Discoloration indicates weathering of rock material and discontinuity surfaces. weathered All rock material may be discolored and weaker than its fresh condition. IB Faintly Discoloration on major discontinuity surfaces. weathered IA Fresh No visible sign of rock material weathering. Idealized weathering profiles - without corestones (left) and Rock decomposed to soil with corestones (right) Weathered/disintegrated rock Rock discolored by weathering Fresh rock Source: Fookes 1997, reproduced with permission of the Geological Society, London. Weathering grades are based on the commonly used classification of Fookes 1997, Komoo and Mogana 1988, and Little 1969. Hydrological properties characterized in terms of particle size distri- bution and structure; bulk density; the ratio of The strength of soils and weathered materials sand, silt, and clays; and the chemical compo- will be affected by moisture content. Increased sition of the clay. These characteristics can be moisture content of slope material causes used as proxies for strength and hydrological increases in pore pressure, which reduces properties based on empirical relationships shear strength. Conversely, the drying of slope (Carter and Bentley 1991). material can cause negative pore pressures For slope stability analysis, a more precise (matric suction), which increase shear measure of soil strength entails laboratory strength (Fredlund 1980; Fredlund and assessment of the geotechnical properties of Rahardjo 1993). The magnitude of pore pres- slope soil samples (figure  3.20). The shear sures associated with wetting and drying are strength of a specific soil can then be described dictated by material properties such as pore in terms of soil cohesion (c, kPa) and angle of size and chemistry. For instance, clay particles internal friction (Φ, degrees), which are the carry a negative charge, which influences the parameters that need to be specified in ana- retention of moisture in the pores. Thus, sandy lytical and numerical slope stability models porous soils may experience little variation in (Nash 1987). strength, while the strength of clay soils can In areas where landslides have already vary significantly with moisture content. occurred, the slope material will have a much The deep residual soils of the humid tropics lower strength than its original intact strength; can often have relatively high hydraulic con- this is its residual strength. ductivities, allowing rainfall to infiltrate rap- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 0 5 idly. Periods of rainfall can result in the forma- F IG U R E 3.1 9  Weathering profiles tion of saturated zones within the soil strata nearer the ground surface. Different material types, when saturated, will exhibit different hydraulic conductivities depending on their structure and composition. In unsaturated conditions, hydraulic conductivity will vary as a function of moisture content. Subsurface water flows within soil pores can be augmented by the development of a network of wider-diameter pipes within the soil (figure 3.21). Soil pipes can be a contribu- a. Grade II material transitioning to Grade III tory factor to landslides by giving rise to locally above. high pore water pressures (Brand, Dale, and Nash 1986; Pierson 1983; Uchida 2004). The effect of pipe flow is also spatially complex— reducing pore pressures in the upslope area covered by the pipe network, while increasing pore pressures in downslope locations, espe- cially if the pipe network is blocked. Sharma, Konietzky, and Kosugi (2009) report numeri- cal model results summarizing this complex relationship. F IGUR E 3 . 2 1  Exposed soil pipe some 30 cm below the soil surface b. Indication of abrupt change in weathering grade from V to VI above. F IG U R E 3. 2 0  Shear box used to determine soil strength parameters Summary: assessment of slope material types and properties • The dominant slope material type can often be determined by referring to soil and geo- logical surveys available from government engineering departments or similar organi- zations. 1 0 6    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D • More precise assessments of material types and Kneale 1982). Since soil water flow takes and strata can be made in the field through place at right angles to the lines of total poten- direct observation, boreholes, or soil pits. tial, soil water flow lines can—again as an approximation—be drawn at right angles to • Material strength can be inferred from topographic contours. It is this logic that gives weathering grades. rise to the construction of potential zones of • Basic descriptions of material characteris- soil water convergence and divergence on a tics can be used to infer strength and hydro- hillslope, as shown in figure 3.22. The two logical properties, using the findings from locations A and B depict zones of convergence numerous studies in the scientific and engi- and divergence, respectively; much higher neering literature. pore water pressures will be anticipated in the former case (due to the concentration of flow), • Areas where there have been previous land- with lower pore water pressures (perhaps slides will have lower (residual) material unsaturated conditions) in the zone of diver- strength. gence. • The specific geotechnical properties (c, Φ) Subtle topographic hillslope hollow fea- of a material can be measured by triaxial or tures (zones of convergence) are important to shear box testing. locate since they represent areas of potential slope instability because of the relatively higher • Material hydrological properties can be pore water pressures, which in turn serve to measured using equipment such as a reduce soil shear strength. This means that permeameter or infiltrometer. failures can occur on relatively shallow slopes, • Pore pressures and subsurface water levels triggered by soil water convergence taking can be measured in the field using a peizo- place upslope. Figure 3.23 shows an example of meter. such a failure on an 18-degree slope; slopes above, with slope angles as high as 45 degrees, 3.5.4 Slope hydrology and drainage remained stable since they lacked the same The dynamic nature of a slope’s response to surface water infiltration and subsurface flows make an understanding of the overall hydrol- F IGUR E 3 . 2 2  Definition of the planimetric ogy of a slope essential for gaining insights into contributing area at two locations in a its stability. hypothetical landscape Convergence zones It is important to identify zones of topographic convergence—elements of the slope that are concave in plan. Convergence zones concen- trate surface water flows and strongly influ- ence subsurface water flows. A Water moves through soils according to the total potential of soil water, being the sum of the gravitational potential (the elevation of the point in the soil above some arbitrary datum) and the pressure potential (either positive or B negative soil water pressure). Other than for the shallowest slopes, topographic contours Source: Iverson 2000. can be considered an approximation of the Note: Blue = planimetric contributing areas; brown lines = topographic contours, with lowest elevations lines of total potential (in that the gravitational at bottom left. potential dominates the equation—Anderson CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 0 7 • High vegetation densities may disguise top- F IG U R E 3. 2 3  Shallow rotational slip on an ographic features. 18-degree slope at the foot of an extensive hillside • Existing contour maps may incorrectly por- tray the detailed slope topography. The following effects of vulnerable unau- thorized communities on drainage should also be noted: • Addition of water to the slope by house- holds (point water sources) • Altered drainage patterns, incomplete drains, or uncontrolled flows • Zones of saturation created by housing structures, modified slope angles, and access degree of topographic convergence, and hence alignments such as footpaths or roads retained lower pore pressures. 3.5.5 Vegetation Urban slope drainage Population growth, urbanization, and poverty Although vegetation may generally have a pos- have led to the development of large vulnerable itive effect on slope stability, it can reduce the communities on steep slopes in many tropical stability of slopes in some cases. areas. If there is a publicly provided piped water Beneficial and adverse effects supply, but no drainage, the discharge of water from houses onto the slope can be significant, Vegetation can influence hydrological and especially when housing density is high. mechanical slope stability mechanisms Sources of water from properties include (table 3.8). gray water from kitchens and bathrooms, leak- In vulnerable urban communities, slope age from supply pipes, and septic tank dis- stability may be influenced by changes in slope charges. The construction of houses, foot- vegetation, such as the following: paths, and drains can change surface and • Removal of deep-rooted vegetation that subsurface water flow patterns on the slope— may have had a stabilizing effect on the typically concentrating them at certain loca- slope material through root reinforcement tions or resulting in zones of constant satura- and uptake of water from the soil tion. Figure 3.24 illustrates a range of common conditions that require identification and • Cultivation of water-demanding plants assessment of their impact. Surface water (such as dasheen; figure 3.25a) that require management measures can then be designed irrigation or the deliberate retention of water on the slope in trenches or terraces—this to improve slope stability. This process is increases infiltration and soil pore water explained in chapters 5–7. pressures, thus reducing soil shear strength Summary: Assessing slope hydrology and • Cultivation of shallow-rooted plants (such drainage as banana and plantain) that add loading to the slope and disturb the soil structure • Shallower slopes at the base of hillsides (increasing soil permeability) without add- may be as, or even more, susceptible to ing root tensile strength landslides as the steeper slopes above because of the convergence of surface and • Planting certain vegetation species for the subsurface water. specific purpose of stabilizing slopes (bio- 1 0 8    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D FI G U R E 3 .24  Common drainage issues in unauthorized communities a. Unauthorized housing is often supplied b. Slope failure caused by lack of water c. A water tank constructed of a single with water delivered through plastic management from upslope unauthor- skin of blocks which failed and caused pipes. ized housing. significant downslope damage. Such structures have the potential to trigger slope instability. d. A drain that is incomplete and may e. Small footpath drain rendered f. Damaged roof guttering discharging thereby cause instability downslope. completely ineffective by routing water to poorly configured drain at the foot supply pipes along its length. of a retaining wall. g. Household septic tank discharging h. High-volume discharges from washing i. Shower and hand-washing water directly into the slope. machines. discharging onto the slope, leading to saturated soil and stagnant water. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 0 9 TAB L E 3 .8  Vegetation influences on slope stability STABILITY VEGETATION MECHANISM EFFECT DESCRIPTION Rainfall interception on foliage increases evaporative losses and reduces infiltration into the slope material Beneficial Uptake of soil water by roots reduces the water content of slope material and therefore reduces pore water pressures Roots increase soil permeability Hydrological Soil moisture depletion may cause desiccation cracking and increase soil permeability Adverse Stem flow and live or decaying roots can generate preferential flow paths within the slope material (macropores and soil pipes), thus increasing the concentration of water in certain locations, particularly if the water is directed to the soil-rock interface, which is a common zone of weakness Roots can provide soil reinforcement and increase soil shear strength Beneficial Tree roots may anchor into firm material at depth and have a buttressing effect in resisting Mechanical the shallow movement of soils Trees are subject to “wind throw” which exerts a force on the slope during high winds Adverse Large trees will significantly increase the loading on the slope engineering); for example, vetiver grass is Vegetation effects on slope stability are thus widely used for its extensive root network complex, being dependent on the nature of the and slope-stabilizing properties (fig- slope and vegetation species. For this reason, ure 3.25b). the relative influence of each of the factors in F IG U R E 3. 2 5  Examples of adverse and beneficial effects of vegetation on slopes a. Water-demanding plants, such as dasheen, the large-leafed plants on the right, may be cultivated in naturally saturated areas, or water may be retained on slopes for this purpose. b. Roots of vetiver grass can grow to some 3 m. 1 1 0    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D table 3.8 will vary from slope to slope. Conse- • The succession of plants on a particular quently, “it is not sufficient simply to classify part of a slope can indicate the location of a individual mechanisms, they must be quanti- previous landslide. fied. Only then can the net influence of vegeta- 3.5.6 Loading tion be clarified and its influence on stability be defined” (Greenway 1987, 192). Construction adds to slope loading, increases the shear stresses acting on the slope, and thus Vegetation as an indicator of past landslides contributes to destabilizing forces. The succession of plants on a particular part of Construction materials and loading a slope can indicate the location of an earlier slope disturbance—an abandoned cultivated In vulnerable communities, unauthorized area, the site of a fire, or a landslide. In the houses are typically enlarged in an incremental tropics, landslide scars and debris will revege- manner. Often, there is a progression from tra- tate within a short time if the soil depth is suf- ditional wooden structures to heavier concrete ficient and nutrients are available (for instance, construction (figure 3.27). This incremental from decomposition of the vegetation mixed construction increases slope loading in terms of into debris or from erosion). Figure 3.26 pres- the weight of the construction material. ents a model of post-landslide vegetation suc- Construction on former landslide zones cession for the Caribbean showing the rela- tionship between slope stability, soil organic A landslide significantly reduces the strength matter, and slope revegetation. of failed slope material—not just along the slip surface, but also within the failed mass. Con- Summary: Assessing vegetation cover struction on previously failed material is com- mon in rapidly developing unauthorized urban • Discussions with local botanical specialists areas in the tropics and may occur immedi- may help establish the net influence of veg- ately after a landslide or several years later etation and local planting practices on slope (figure 3.28). Rapid reconstruction on the site stability. of a landslide reflects the severe pressure for • The presence of certain species on slopes housing that can lead to residents discounting can indicate either natural or manmade the hazard, in full knowledge of past failure. In saturated conditions. the case of historic landslides, the majority of FI G U R E 3 .26  Model of post-landslide vegetation succession for the Caribbean newly exposed nonvascular plants mineral soil unstable pioneer trees residual forest pioneer shrubs soil landslide climbing ferns mature forest soil newly exposed grasses, herbs pioneer trees mineral soil pioneer trees stable residual forest pioneer shrubs mature forest soil 0.1 1 10 100 1,000 landslide age (years) Source: Walker et al. 1996. Note: Four plant succession pathways for landslides in a low-elevation forest in Puerto Rico. On unstable soils, erosion constantly resets succession (dotted lines). On stable soils, filled squares indicate age at which pre-landslide vegetation may reestablish. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 1 1 F IG U R E 3. 2 7  Examples of incremental construction a. Additional loading of a 55-degree slope with an b. Property enlarged by building outside the already high housing density increases landslide risk. existing walls. the community may be unaware of past slope 3.6 SCIENTIFIC METHODS FOR history and the associated potential hazard. In ASSESSING LANDSLIDE both cases, the effect of construction in such HAZARD locations is to reduce slope stability in all the ways discussed here, potentially reactivating a To assess the landslide hazard affecting a par- landslide or triggering new ones. ticular hillside community requires a method that can account for the roles of the different Summary: Assessing loading and former slope stability variables described in the pre- landslides vious section at the correct scale and over time. This assessment can indicate potential • Housing density and construction type can landslide hazard mitigation strategies such as be rapidly assessed from aerial photo- surface water management for intercepting graphs. rainfall runoff and household water, and • More detailed site surveys will reveal the reducing infiltration (the approach taken by interaction between loading and slope mate- MoSSaiC). rial. In section 3.4, physically based slope stabil- ity models noted as being particularly relevant • Areas of very old large landslides may have for MoSSaiC were those that represent slope become masked by dense vegetation growth mechanical processes and dynamic hydrologi- and subsequent construction. cal processes at local hillside/community • An integrated interpretation of local geol- scales. Many of the slope stability variables ogy, topography, variations in soil depth, described in section 3.5 are used as inputs to boulder locations, and vegetation can help physically based models, thus allowing their identify landslides that occurred before liv- relative roles in determining slope stability to ing memory. be analyzed. The community-based mapping 1 1 2    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D FI G U R E 3 .28  Examples of reconstruction on former landslide sites a. Unauthorized housing built on a preexisting b. Houses built on the site of a landslide that landslide within one year of the failure having affected the whole hillside approximately 90 taken place. years previously. and measurement of these variables is a particular slope. If surface water infiltration described in chapter 5. from rainfall and piped water supplies is the This section introduces three physically driving factor in slope failure, this form of based (scientific) methods for assessing land- simulation can allow the potential effective- slide hazard. ness of surface drainage to be investigated. The use of coupled hydrology-stability mod- • Coupled dynamic hydrology and slope els is an important part of the design and sci- stability models to simulate physical pro- entific justification of any drainage measures cesses affecting slope stability over time aimed at reducing the landslide hazard. Esti- (including dynamic hydrology), identify mating the impact of surface water infiltra- dominant landslide causes, and predict tion—and thus the effectiveness of potential landslide hazard (probability, magnitude, drainage measures—demands a numerical location) model that incorporates dynamic hydrology • Resistance envelope calculations to so the slope stability response can be simu- determine whether negative pore pressures lated over time. are required to maintain the stability of a Several numerical models are available that slope would allow such an analysis (see http://www. ggsd.com). One example is CHASM (Com- • Static analysis of retaining walls to deter- bined Hydrology and Slope Stability Model) mine the stability of retaining walls. software, which has been developed by the The above is not intended to be an exhaus- authors and used in numerous research and tive list of landslide hazard assessment meth- practical applications to date, including ods, but rather demonstrates the level of pro- MoSSaiC. The following overview of CHASM’s cess representation that is required and that structure and capabilities is based on this can be realistically achieved in the context of experience and is in no way intended as an MoSSaiC. endorsement. The overview may assist the MCU in discussions regarding the selection of 3.6.1 Coupled dynamic hydrology and appropriate slope stability models. It is beyond slope stability models the scope of this text to review the suitability Coupled dynamic hydrology and slope stabil- of all such potential models for particular ity models can allow the identification of applications. In any event, it is likely that local those processes that dominate the stability of engineers will be familiar with, and have CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 1 3 access to, other slope stability models that may the dynamic rainfall conditions for each be suitable for MoSSaiC interventions. hour of the simulation. Model configuration • The slip surface search mode is also defined, searching for the location of either a circu- The main features of CHASM are described in lar or noncircular slip surface with the low- Anderson et al. (1996, 1997) and Wilkinson, est factor of safety. Brooks, and Anderson (1998, 2000), among others. Figure  3.29 shows how a slope cross- Dynamic hydrology component section is represented in CHASM; the princi- ple equation set is given in section  3.7.4. The Within CHASM, infiltration during rainfall is simulation is configured as follows: calculated using Darcy’s Law; vertical flow in the unsaturated zone is computed using Rich- • The slope is divided into regular columns ards’ equation solved in explicit form inside and cells, the centers of which form compu- vertical columns. Within the integrated model tational points for the solution of equations structure, the hydrology scheme represents for slope hydrology. slope plan curvature (convexity and concav- • Each cell is assigned a material type, and ity) by varying the breadth of the columns (fig- the strength and hydraulic properties of ure 3.30). The pseudo-effect of the three- each material are specified (in this example, dimensional topography on water fluxes can there are three material types). thus be investigated and its impact on stability estimated (GCO 1984). • Vegetation, slope loading, and point water sources can be defined for specific surface Slope stability component cells. At the end of each simulation hour, the pore • Hydrological boundary conditions are pressure field generated by the hydrology defined—the initial estimated position of component is used as input to standard two- the water table, the initial moisture content dimensional stability analyses where the slip of each cell, the initial surface suction, and surface is located within the midplane of the three-dimensional structure. CHASM uses Bishop’s (1955) simplified circular method FI G U R E 3 .29  Representation of a slope cross-section for analysis with an automated search procedure (Wilkin- in CHASM software son, Brooks, and Anderson 2000), or Janbu’s noncircular method for estimation of the precipitation slope’s factor of safety (Nash 1987). Pore pres- evaporation slip search grid sures, both negative and positive, are incorpo- runoff rated directly into the effective stress determi- nation of the Mohr-Coulomb equation for soil shear strength. This allows derivation of the slip circle minimum factor of safety with temporal varia- slope profile for stability model tions arising from hydrodynamic responses and changes in the position of the critical slip soil 1 surface (Wilkinson 2001). modeled water table Other useful features for identifying hazard soil 2 drivers CHASM’s numerical scheme includes a sur- soil 3 face cover model, which allows investigation of the hydrological and geotechnical effects of vegetation on slope stability. Vegetation 1 1 4    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D affects slope stability through rainfall inter- ception, evapo-transpiration, changes in F IGUR E 3 . 3 0  CHASM representation of a natural hillslope hydraulic conductivity, root reinforcement, noncircular and surface loading—all of which are included slip search R ET in the model (Collison 1993; Wilkinson, Brooks, and Anderson 1998; Wu, McKinnell, and Swanston 1979). RO Piped water is often supplied to hillside I communities. In unauthorized communities, WT there is usually no drainage or sewerage provi- evaporation & rainfall Q transpiration interception sion, so gray water from sinks and bathrooms is discharged directly to the slope. Foul water drainage goes to a septic tank or pit latrine usually within a few meters of the property, R rainfall leaf ET evapotranspiration the outflow from which returns directly to the drip RO runo slope. It is possible within CHASM to assign stemflow I infiltration Q lateral flow leakage at defined points on the slope surface water uptake WT water table with specified flux rates by increasing the by roots effective rainfall to the grid columns where runo water leakage into the slope has been identi- increased fied. infiltration Unauthorized housing density can deep percolation approach 70 percent of the surface area of slopes—adding significant loading. Building Source: Adapted from Wilkinson et al. 2002. loads need to be taken into account when establishing comparative influences on slope stability. In Bishop’s method, loading is incor- porated by increasing the weight of the slices D.C., in 2010. The simulation time-step shown on which the buildings are located. here is toward the end of a 1-in-100-year, 24-hour rainfall event, in which the factor of Interpreting simulation results safety has fallen from approximately 1.32 to For each computation time-step of the simula- 1.28. Perched water tables are visible at the tion, the typical outputs of models such as interface between the upper two soil strata. By CHASM include the end of the storm, F is predicted to be approximately 1.25 before recovering as the • predicted slip surface location, water table drops. Although a landslide is not • pore water pressure and soil moisture fields predicted (F > 1), the weakest part of the slope throughout the slope, and can still be identified from the location of the slip circle. • factor of safety. Slope stability models with features similar These outputs can often be directly visual- to those outlined above, and that include the ized in the model’s graphic user interface or dynamic modeling of pore pressure conditions may simply be in the form of text files. Text file (both positive and negative), allow determina- outputs can be graphically represented using tion of the impact of rainfall as a landslide trig- standard software such as R, Matlab, or IDL. gering mechanism. Using a model with these Figure 3.31 presents the graphical representa- attributes, an assessment can be made of the tion of CHASM outputs using open source likely impact of surface water management as software developed by volunteers at the Ran- a means of contributing to improving slope dom Hacks of Kindness event in Washington, stability. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 1 5 PHYSICALLY BASED SLOPE STABILITY MODELS • Simulation of the physical processes affecting slope stability USAGE • Identification of dominant landslide causes • Landslide hazard prediction (probability, magnitude, location) SOURCE See http://www.ggsd.com for a comprehensive listing of slope stability software FURTHER See section 5.6.3 for CHASM application DISCUSSION 3.6.2 Resistance envelope method for which the slope may be expected to remain determining suction control stable (Anderson, Kemp, and Shen 1987). The resistance envelope method can be used In the resistance envelope method, several to determine whether negative pore pressures slip surfaces are assumed and the average are required to maintain the stability of a slope. shear strength required for equilibrium is The apparent significance of slope drainage determined (using an appropriate method of can be corroborated using resistance enve- analysis, such as Bishop 1955) along each of lopes to identify the controls on slope stability the surfaces, together with the corresponding (Chowdhury, Flentje, and Bhattacharya 2010; average normal stress. The average mobilized Fredlund 1980; Janbu 1977; Kenny 1967). shear strength is then plotted against the aver- Resistance envelope calculations can be used age effective normal stress, with each point on to show either the average negative pore pres- the plot representing a critical slip surface. sure required for the maintenance of stability Joining all these points together forms the or, conversely, the saturated conditions under resistance envelope, onto which the plot of the F IG U R E 3. 31  Outputs from a CHASM simulation Slope Factor of Safety and Precipitation 1.26 16 1.24 14 precipitation mm h−1 1.22 12 factor of safety 1.2 10 1.18 8 1.16 6 1.14 4 1.12 2 1.1 0 0 50 100 150 200 250 300 350 hours Source: Prototype visualization software created at Random Hacks of Kindness event 2010. 1 1 6    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D shear strength of the soil can be superimposed can reasonably be attributed to infiltration (Chowdhury, Flentje, and Bhattacharya 2010). controls. The methodology assumes negative pore pres- sures act directly in effective stress terms. Fig- 3.6.3 Modeling the impact of small ure 3.32 provides a generalized illustration of retaining walls the superimposition of the resistance envelope Many residents in vulnerable communities and the laboratory-determined soil strength seek to reduce landslide risk by constructing envelope for a case in which the slope is single-skin, reinforced block retaining walls dependent upon soil suction (negative pore (figure 3.34). Such walls are common because pressures) for stability. they can be constructed at the household level, Application of the method to a site in the require no community consensus or govern- Eastern Caribbean is illustrated in figure 3.33. ment permission, and can be built progres- Using two different pairs of values for the geo- sively as the resident accumulates funds to technical properties (effective cohesion, c', purchase materials. But even if they are expe- and effective angle of internal friction, Φ'), obtained from two separate sites on the slope, F IGUR E 3 . 33  Resistance envelope plots the results suggest that the slope must be shear strength kPa maintained at either 50 • marginal negative pore pressure (fig- 40 ure 3.33a; c' = 10 kPa, Φ' = 20 kPa), since for normal loads in excess of 50 kPa, the resis- 30 tance envelope shows marginally greater 20 lab results shear strength is required for stability than can be mobilized by the slope material (as 10 resistance envelope indicated by the laboratory shear strength 0 values used); or 0 10 20 30 40 50 60 70 normal load kPa 80 90 100 • very low positive pressures (figure 3.33b; a. The graph shows negative suction is required c' = 10 kPa, Φ' = 25 kPa). to bring the mobilized shear strength equal with the resistance envelope (for normal loads > 50 kPa; for material properties c' = 10 kPa, It is to be inferred that significant rainstorm Φ' = 20 kPa). events will, through lack of drainage provision on the slope, increase pore pressures beyond shear strength kPa 60 those limits, thus suggesting that instability 50 40 FI G U R E 3 . 32   Superimposition of resistance 30 and strength envelopes lab results 20 saturated strength S2 envelope 10 Fmin = shear strength, τ, kPa S1 dry resistance envelope resistance envelope 0 S2 0 10 20 30 40 50 60 70 80 90 100 Ur S1 normal load kPa S1 = strength available S2 = strength required b. Only a modest increase in pore pressure is Ur = suction required to maintain slope stability required to lower the mobilized shear strength to the resistance envelope (material properties, a (σ - Uw) c' = 10 kPa, Φ' = 25 kPa). Source: Anderson, Kemp, and Shen 1987. Source: Anderson, Kemp, and Shen 1987. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 1 7 RESISTANCE ENVELOPE METHOD USAGE To determine whether negative pore pressures are required to maintain slope stability SOURCE Resistance envelope calculation in Anderson et al. (1997) FURTHER See section 5.6.4 DISCUSSION F IG U R E 3. 34  Inadequate retaining wall unlikely to provide an effective landslide risk design reduction measure. The essential general sta- bility requirements for such structures would appear to be drainage to ensure the mainte- nance of unsaturated conditions behind the wall, and an avoidance of surcharging the slope immediately behind the wall. In reality, these two conditions are not likely to be met in such communities with unauthorized hous- ing. Alternative retaining wall designs incor- porating features to counteract overturning failure, such as wall backtilt and an extended a. Typical failure of modest retaining wall built wall toe, would also seem impractical in this by resident. context, given their increased costs over sim- ple walls and the greater construction control required to ensure structural integrity. Summary: landslide hazard assessment methods • Review slope stability software available either locally or online. • Use the resistance envelope method for assessing the role of negative pore pres- sures, only if there is adequate technical b. Retaining wall built by resident failed, with support for the analysis and interpretation lower part of wall displaced to rear of property. and if circumstances warrant that discrimi- nation. • Use retaining wall analysis software to gen- dient, are such structures effective? Given the erate local case studies to affirm the type of number of such retaining wall failures, it is structures that would be needed to enhance important to assess the stability of a typical slope stability. Assess whether such struc- structure so clearer guidance can be given to tures would be affordable and desirable at community residents. the community scale. For this purpose, a standard static hydrol- ogy retaining wall stability analysis can be undertaken (see, e.g., BSI 1994; Craig 1997; and MILESTONE 3: USACE 1989). The findings of such an analy- Presentation made to MoSSaiC sis, outlined in section 3.7.5, suggest that sim- teams on landslide processes and ple single-skin structures of the type com- monly constructed by residents are unlikely to slope stability software meet the stability criteria—and are equally 1 1 8    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D 3.7 RESOURCES 3.7.1 Who does what CHAPTER TEAM RESPONSIBILITY ACTIONS AND HELPFUL HINTS SECTION Know the types of landslides • Become familiar with the specific types of landslides that 3.3 addressed by MoSSaiC MoSSaiC seeks to address Funders and policy makers Coordinate with the MCU for any technical information required Understand the types of • Become familiar with the specific types of landslides that 3.3 landslides addressed by MoSSaiC MoSSaiC seeks to address Understand the factors that 3.4; 3.5 determine slope stability and the MCU associated assessment methods Coordinate with government task team for any technical information required Understand the types of • Become familiar with the specific types of landslides that 3.3 landslides addressed by MoSSaiC MoSSaiC seeks to address • Look at this chapter, field sites, and local reports of 3.4; 3.5 Understand the factors that landslides to appreciate all the possible triggering determine slope stability and the mechanisms associated assessment methods Helpful hint: Undertake site visits to landslide sites and identify types and potential localized causes. Be familiar with, and select • Review relevant slope stability assessment methods with 3.6 appropriate, scientific methods respect to software, expertise, and data likely to be for assessing local landslide locally available Government task hazards teams Brief the MCU and all task teams • Landslide assessment and engineering task team should Whole on (1) the scope of MoSSaiC with prepare and deliver presentation chapter respect to local landslide types; (2) landslide preparatory, aggravating, and triggering factors; and (3) the scientific basis for assessing slope stability, especially with respect to locally available expertise and software Coordinate with community task teams when appointed Community task • Look at this chapter, visit field sites (this is especially 3.5 When appointed, understand the teams important), and review local reports of landslides to variables that affect slope appreciate all the possible preparatory, aggravating, and stability triggering mechanisms Coordinate with government task teams CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 1 9 3.7.2 Chapter checklist SIGN- CHAPTER CHECK THAT: TEAM PERSON OFF SECTION 99Knowledge has been acquired of the subset of landslide types that MoSSaiC 3.3 seeks to address 99Knowledge has been acquired of relevant slope stability processes 3.4; 3.5 99Site visits to known and potential landslide sites to examine potential triggering mechanisms and suitability for MoSSaiC approach have been 3.3; 3.4; 3.5 undertaken 99Potential scientific tools for assessing landslide hazard have been examined 3.6 99Milestone 3: Presentation made to MoSSaiC teams on landslide processes and slope stability software 99All necessary safeguards complied with 1.5.3; 2.3.2 3.7.3 Rainfall thresholds for triggering θi = unsaturated moisture content (m3 m−3) landslides θs = saturated moisture content (m3 m−3) ψi = suction value at moisture content θi (m) The website developed by the Italian Istituto m = number of equal increments of θ from di Ricerca per la Protezione Idrogeologica θ = 0 to θ = θs (IRPI) contains a comprehensive worldwide j,i = summation indexes listing of rainfall threshold triggering relation- Mohr-Coulomb equation (Coulomb 1776) ships (http://wwwdb.gndci.cnr.it/php2/rain- fall_thresholds/thresholds_all.php?lingua=it). s = c' + ( σ − u ) tan φ' 3.7.4 CHASM principle equation set s = soil shear strength (kPa) The following equation sets are from Wilkin- c' = effective soil cohesion (kPa) son et al. (2002). See table 3.9. Φ' = effective angle of internal friction (degrees) σ = total normal stress (kPa) Richards’ equation (Richards 1931) u = pore water pressure (kPa) ∂θ ∂  ∂θ  ∂Κ Bishop stability equations (Bishop 1955) =− D  − ∂t ∂ z  ∂ z  dz ∑ ( c'l + ( P − ul ) tan φ' ) n θ = volumetric moisture content (m3 m−3) FS = i=0 ∑ W tan α n t = time (s) i=0 z = vertical depth (m) D = hydraulic diffusivity (m2 s−1) where Millington-Quirk equation (Millington and Quirk  1  P = W − ( c'l sin α − ul tan φ' sin α ) / mα 1959)  FS 0  m ∑ (( 2 j + 1 − 2i ) ψ ) j −2 and K i = K s (θ i / θ s ) p j =i m  tan φ'  ∑ (( 2 j − 1) ψ )j −2 mα = cos α  1 + tan α  FS0   j =1 p = pore interaction term Ki = unsaturated conductivity (m s−1) n = number of slices Ks = saturated conductivity (m s−1) 1 2 0    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D TAB L E 3 .9  Units for the parameters used in CHASM PARAMETER GROUP PARAMETER NAME SYMBOL/UNIT Slope height H (m) Feature geometry Slope angle α (degrees) Slope plan convergence/divergence radius C (m) Mesh resolution (width, depth, breadth) a w, d, b (m) Numerical Iteration period a t (s) Rainfall p (m s−1) Saturated hydraulic conductivity Ks (m s−1) Hydrological Initial surface suctionb ψt0 (m) Initial water table height b wt (% slope height) Suction-moisture curve ψ (m) –θ (m3 m−3) Effective angle of internal friction Φ' (degrees) Geotechnical Unsaturated/saturated bulk density γus, γs (kN m−3) Effective cohesion c' (kN m−2) Root tensile strength τr (kN m−2) Vegetation cover/spacing vc (%), vs (m) Leaf area index lai (m2 m−2) Aerodynamic resistancec ra (s m−1) Vegetation Canopy resistancec rc (s m−1) Canopy/trunk storage capacity cs, ts (m) Root depth/lateral extent Rd, Rl (m) Vegetation surcharge Sw (kN m−2) Net radiation Rn (W m−2) Atmosphericc Relative humidity Rh (%) Temperature T (0C) a. Determined according to Beven (1985) to maintain numerical stability in Richards’ equation. b. Initial surface suction and water table heights (defined as percentage of slope height measured to the toe of the slope) are assigned according to measured field conditions or hypothetical scenario. Richards’ equation is then iterated until steady-state conditions are attained or the required soil moisture conditions are reached. c. Atmospheric variables and canopy/aerodynamic resistance are required if the user wishes to determine soil evaporation and evapotranspiration using the Penman-Monteith equation. In the absence of this information, a sinusoidal function is used with the maximum evaporation rate defined at midday The sinusoidal function operates between 0600 and 1800 hours. During the remaining time, the respective evaporation rate is set to 1/100th of the midday maximum. Penman-Monteith equation (Monteith 1973) FS = factor of safety c' = effective soil cohesion (kPa) Rn + ρc pVPD / ra l = slice length (m) Ep = Δ+γ (1 + rc / ra) λ   α = slice angle (degrees) u = pore water pressure (kPa) Ep = potential evapotranspiration rate (m s−1) Φ' = effective angle of internal friction (degrees) ra = aerodynamic resistance (s m−1) W = weight of the soil (kPa) rc = canopy resistance (s m−1) Δ = slope of the saturation vapor pressure— temperature curve (kg m−3 K−1) CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 2 1 λ = latent heat of vaporization of water wall, groundwater included as a specified hor- (≈ 2.47 × 106 J kg−1) izontal water table position, unsaturated earth ρ = density of air (≈ 1.2 kg m−1) pressures acting above the saturated ground- γ = psychrometric constant (γ ≈ 66 Pa K−1) water level, and saturated earth pressures and VPD = vapor pressure deficit (kg m−1 s−2) direct hydrostatic pore water pressures acting cp = specific heat of air (J kg−1 K−1) below. Details of the specific methodology Rn = net radiation (W m−2) may be found in Blake (2003). No uplift water force on the base of the wall Root reinforcement equation (Wu, McKinnell, or at the front of the wall was considered. The and Swanston 1979; Wu 1995) active earth pressure was calculated using the Δc' = c'R = tR(cosθ tanΦ + sinθ) Coulomb coefficient method. Factors of safety c' = effective cohesion (kPa) against sliding, overturning, and bearing-limit- c'R = effective cohesion attributed to the root state retaining wall stability failure modes network (kPa) were determined. θ = angle of shear rotation (degrees) Earth pressures in front of retaining walls Φ = angle of internal friction (degrees) and the possibility of tension cracks in the tR = average tensile strength of the roots per retained material both need to be considered. unit area of soil (kPa) No passive earth pressures acting in front of the wall were included in this analysis, which 3.7.5 Static hydrology retaining wall is a common conservative assumption. In real- stability analysis ity, the wall stability will be increased slightly The following describes a simple retaining by this force although it cannot be relied upon wall stability analysis by Anderson et al. (2011). due to unplanned excavations in front of the A simple wall geometry was defined (fig- wall. Tension cracks resulting from the ure  3.35) with the following specifications: retained material cohesive properties were active earth pressure acting on the back of the included in the analysis, with their depth cal- culated using the method given in Craig (1997). Their effect is to reduce the stability benefits FI G U R E 3 . 3 5  A simple retaining wall geometry used for the of the cohesive element of the retained mate- retaining wall analysis rial. Similarly, no account was taken of any surface water filling these cracks and exerting detri- tension mental additional hydrostatic pressure on the cracks wall. Cohesion reduces the horizontal compo- 0.3m 0m 25˚ overturning nent of the total active earth pressure on the failure mode back of the wall (a stabilizing effect) while also 0.3m unsaturated earth resulting in adhesion between the wall and the water- pressures (above retained material. Thus, the effect of cohesion 0.6m table water table) 1.5m is to reduce the effectiveness of the wall weight depth 0.9m vertical wall (a destabilizing effect). scenarios Using these specifications, an analysis was 1.2m saturated earth undertaken for the following horizontal water pressures and table depths (with hydrostatic pore water 1.5m direct hydrostatic pore pressures pressure distribution) below the ground sur- (below water sliding failure face: 1.50 m (at base of wall—fully unsaturated mode table) retained material), 1.20 m, 0.90 m, 0.60 m, bearing failure mode 0.30 m, 0.00 m (at top of wall—fully saturated retained material). Source: Anderson et al. 2011. The stability analysis parameters and results are given in table 3.10. The results show 1 2 2    C H A P T E R 3 .   U N D E R S TA N D I N G L A N D S L I D E H A Z A R D TAB L E 3 .10  Results of an illustrative standard static hydrology retaining wall stability analysis WATER TABLE NO SURCHARGE 10 kN m−2 SURCHARGE DEPTH BELOW Overturning Sliding Bearing Overturning Sliding Bearing SURFACE (m) failure failurea failure failure failure failure 1.50 1.79 −1.74 4.47 0.22 0.55 0.58 1.20 1.72 −1.90 4.38 0.22 0.54 0.58 0.90 1.39 −2.65 3.89 0.21 0.50 0.57 0.60 0.90 −8.13 3.00 0.20 0.44 0.55 0.30 0.51 4.03 2.09 0.17 0.38 0.51 0.00 0.28 1.33 1.40 0.15 0.32 0.45 Source: Anderson et al. 2011. a. In the factor of safety calculation, while negative values are possible, such solutions have no physical meaning. Note: Parameter values used for the analysis: Wall unit weight: 23 kN m−3 (concrete blocks) Retained material unsaturated unit weight: 15 kN m−3 Retained material saturated unit weight: 19 kN m−3 Effective cohesion: 10 kPa Wall adhesion: 5 kPa (standard assumption of cohesion ÷2) Effective angle of internal friction (Φ): 25° Wall-backfill friction angle: 13° (standard assumption of Φ ÷2) Wall-foundation friction angle: 17° (standard assumption of 2 × Φ ÷3) Foundation bearing capacity: 400 kN m−2 Surcharge: 0 or 10 kN m−2 (it is usual to have a conservative assumption of 10 kN m−2 minimum to provide a margin of safety against unplanned loads, vehicle movement, etc.) that if there is a modest (10 kN m−2) surcharge, tion enhanced material shear strength is not the wall will be unstable for all failure modes accounted for. However, this is not considered and water table scenarios. Comparison with material to the broad conclusions given in the Hong Kong SAR, China, Geotechnical table 3.10. Control Office (GCO 1984) critical stability threshold factor of safety values (overturning: 3.7.6 References 1.50, sliding: 1.25, bearing: 3.00) shows that the Aleotti, P., and R. Chowdhury. 1999. “Landslide wall will meet these design thresholds provid- Hazard Assessment: Summary Review and New Perspectives.” Bulletin of Engineering Geology ing the material behind the wall remains and the Environment 58: 21–44. unsaturated. The overturning failure mode is critical, an observation in agreement with field Anderson, M. G., A. J. C. Collison, J. Hartshorne, D. M. Lloyd, and A. Park. 1996. “Developments evidence of overtilted retaining walls. This is in Slope Hydrology—Stability Modelling for explained partly by the fact that (beneficial) Tropical Slopes.” In Advances in Hillslope soil cohesion has a smaller effect on the wall Processes, ed. M. G. Anderson and S. M. overturning moment, since tension cracks Brooks, 799–821. 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CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 2 7 “How can we encourage developing countries to invest more in disaster risk reduction? We need to help governments make the choices of where to invest.” —Department for International Development, “Frequently Asked Questions on Disaster Risk Reduction” (2006) CHAPTER 4 Selecting Communities 4.1 KEY CHAPTER ELEMENTS 4.1.1 Coverage This chapter outlines the process for identify- (Management of Slope Stability in Communi- ing the communities most at risk from land- ties) projects. The listed groups should read slides so they can be prioritized for MoSSaiC the indicated chapter sections. AUDIENCE CHAPTER F M G C LEARNING SECTION    Principles for comparing landslide risk at various locations; data and expertise 4.1, 4.2, 4.3 required; how to design an appropriate community prioritization process   How to compare landslide susceptibility or hazard at multiple locations 4.4    How to compare the vulnerability of exposed communities 4.5   How to create a prioritized list of at-risk communities 4.6  How to create a base map for each selected community 4.7 F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors 4.1.2 Documents CHAPTER DOCUMENT TO BE PRODUCED SECTION Report on decision-making process, roles, and responsibilities for community selection 4.1, 4.2, 4.3 Report on outcomes of landslide susceptibility/hazard assessment and vulnerability assessment 4.4, 4.5, 4.6 concluding with a prioritized list of communities for engagement in MoSSaiC project Base maps for the selected communities 4.7 129 4.1.3 Steps and outputs STEP OUTPUT 1. Define the community selection process Agreed-upon • Identify available experts in government selection method • Determine availability of software and data and criteria, roles • Request permission to use data if necessary and responsibilities, • Design appropriate method for selecting communities timeline 2. Assess landslide hazard List or map of • Data acquisition: topography, soils, geology, land use, past landslides relative landslide • Data analysis: landslide susceptibility or hazard within the study area susceptibility of different areas 3. Assess exposure and vulnerability List or map of • Data acquisition: community locations, building footprints, housing/popula- relative tion density, census data or poverty data vulnerability of exposed • Data analysis: vulnerability of exposed communities to landslide impacts in communities terms of physical damage, poverty, or other criteria 4. Assess landslide risk List or map plus list • Data analysis: landslide susceptibility/hazard, exposure, and vulnerability data of most-at-risk combined to determine overall landslide risk for study area communities for possible risk • Data analysis: identify communities exposed to highest levels of landslide risk reduction measures 5. Select communities Prioritized • Conduct brief site visits of short-listed communities to confirm results community short list • Consult community liaison task team and other relevant local stakeholders to review list • Confirm prioritized community short list according to selection criteria 6. Prepare site map information for selected communities Hard-copy map • Data acquisition: most detailed maps and aerial photos of selected communities and aerial photo • Map preparation: assemble community maps/photos and print hard copies for use on site 4.1.4 Community-based aspects munities for implementation of landslide haz- ard reduction measures using MoSSaiC. This A critical part of the selection process is for community selection process identifies government task teams to visit short-listed (1) areas where slopes are susceptible to land- communities to confirm the likely landslide slides, (2) the exposure and vulnerability of risk and the suitability of a MoSSaiC project. communities to these potential landslide Community representatives can provide infor- events, (3) the overall landslide risk, and mation on local landslide history, socio- (4) the suitability of a MoSSaiC project for at- economic vulnerability, and community per- risk communities. ceptions of the risk; they should be consulted The sophistication of the methods used will during these visits. depend on local data and software availability, and the level of expertise of the government task teams. Outputs could range from a simple 4.2 GETTING STARTED prioritized list of communities to a detailed landslide risk map for a region or country. A 4.2.1 Briefing note variety of different approaches might be adopted in performing this task. Whatever The aim of this chapter is to provide a frame- method is used, community selection should work for developing a prioritized list of com- be justifiable in terms of the scientific ratio- 1 3 0    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S nale underpinning the landslide risk assess- spatially distributed analysis of risk over wide ment. areas). Once the communities have been selected, The MCU should oversee the development the mapping task team assembles the most- of the method for community selection and be detailed maps available for these communi- responsible for deciding the final list of prior- ties. These maps form the basis for the com- ity communities. A lead investigator should be munity-based landslide hazard and drainage selected to coordinate the multidisciplinary mapping exercise (described in chapter 5) and process of data acquisition and analysis. Dif- subsequent implementation of appropriate ferent task teams should work together to hazard reduction measures. combine their understanding of slope pro- cesses and landslide hazard, technical exper- Why a community selection process is needed tise in data management and/or GIS mapping, The aim of a MoSSaiC intervention is to reduce and experience in vulnerability or poverty landslide hazard in the most vulnerable com- assessment. munities. In any country or region, there may be 4.2.2 Guiding principles many communities at risk, and government The following guiding principles apply in awareness of these communities will vary. The selecting communities for MoSSaiC project MoSSaiC core unit (MCU) should agree on a interventions: process by which communities are selected for • Be realistic about the data, time, and exper- this type of landslide risk reduction project. tise available for the community selection Having a structured approach to commu- process. It is better to design a simple, low- nity selection also ensures that community tech, but achievable decision-making pro- inclusion, exclusion, and prioritization can be cess than to attempt to use software and justified to the communities, the government, techniques for which there is insufficient and donor agencies. Therefore, the selection expertise or poor quality data. process should make use of any relevant quan- titative data relating to landslide susceptibil- • The community selection process should ity/hazard and community vulnerability. It be transparent, regardless of the quality of should also be able to incorporate qualitative the data or the sophistication of the land- data such as local knowledge, reports from slide hazard and vulnerability assessment communities, and information from govern- methods, so that priorities and decisions ment ministries (such as public works, social can be justified to all stakeholders. This development, and emergency management). transparency assists in explaining decisions to residents in communities that may sub- Key activities, resources, and teams sequently not be selected, avoiding bias The community selection process primarily toward particular individuals or agendas in involves data acquisition and analysis. Data decision making, and enabling the project may be in the form of maps and lists of known to be more easily audited and evaluated. or suspected landslides; digital maps of land use, topography, drainage, soil, and geology; 4.2.3 Risks and challenges and data relating to vulnerability (such as cen- sus data at enumeration district level or bet- Limited available data ter). Depending on the scope of the study and the available data and expertise, the analysis The community selection process requires the may be carried out using spreadsheet or data- comparison of the landslide risk affecting mul- base software (to compile and compare data tiple communities. This may be done as a on a list of communities), or a geographic search for at-risk communities over a wide information system (GIS) (for mapping and area (with no prior knowledge of which com- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 3 1 munities may be identified), or may involve slide initiation; hazard maps additionally comparing known at-risk communities. Both convey the temporal probability of land- approaches require data—the type, quality, slide initiation. and availability of which will determine the community selection method used. Test the provenance and utility of other Whatever data are used in the community types of data, such as community vulnerability selection process, be transparent about their information, in a similar manner before source and quality when presenting results to including it in the risk analysis. decision makers and communities. 4.2.4 Adapting the chapter blueprint to Interpreting landslide hazard maps existing capacity When using preexisting landslide hazard Use the matrix opposite below to determine maps be aware how they were generated the availability of physical data (relating to because this affects how they should be inter- landslides), vulnerability data, software, and preted. the expertise of the government team. As described in chapter 3, several different 1. Assign a capacity score from 1 to 3 (low to factors can act together to cause landslides. high) to reflect existing capacity for each These factors can vary over very short dis- element in the matrix’s left-hand column. tances and also over time. The best landslide hazard maps are based on a combination of 2. Identify the most common capacity score as accurate, high-resolution digital maps of these an indicator of the overall capacity level. factors and records of past landslides. Devel- 3. Adapt the blueprint in this chapter in accor- oping such maps requires a good understand- dance with the overall capacity level (see ing of the processes that cause landslides and guide at the bottom of the opposite page). experience in using GIS and spatial data sets. A landslide hazard map based on inaccurate, incomplete, or low-resolution data, or on faulty scientific assumptions, can be mislead- 4.3 DEFINING THE COMMUNITY ing. SELECTION PROCESS Assess the provenance and utility of preex- isting landslide hazard maps in terms of the The community selection process comprises following: two integrated methods—a landslide risk assessment at multiple locations and the appli- • The data used to compile the map, and its cation of decision-making criteria for selecting quality and resolution—These data can communities. The selection process will be include environmental (preparatory) fac- constrained by the technical capacity for land- tors, triggering factors, and past landslides slide risk assessment and the scope of the proj- • The type of landslide represented— ect as defined by funders and government. MoSSaiC is directed toward rotational and For a given technical capacity and project translational slides in weathered materials scope, use the guidance in this section to iden- tify the following: • The expertise of the map maker and the method used—Methods include direct • A suitable approach to comparing levels of landslide mapping, semi-quantitative index landslide risk at multiple locations overlay methods, and spatially distributed • The criteria for community selection modeling of slope factor of safety • The data requirements for the community • The slope stability information conveyed by selection process the map—Landslide susceptibility maps show the relative spatial likelihood of land- • The roles of the MCU and task teams 1 32    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S EXISTING CAPACITY CAPACITY ELEMENT 1 = LOW 2 = MODERATE 3 = HIGH Local geotechnical expertise No local geotechnical experts Geotechnical engineers or Geotechnical engineers or and no local knowledge of academics with some academics with expertise in landslide processes or hazard experience of landslide hazard landslide hazard assessment in assessment assessment in the field or in the field and in using GIS using GIS Digital map availability No digital maps Some digital maps available or High-resolution digital maps at low resolution available Preexisting landslide suscepti- No (or poor quality) landslide Relevant landslide susceptibil- Good quality, high-resolution, bility, hazard, or risk maps susceptibility/hazard maps ity map available, sufficient relevant landslide susceptibil- resolution and quality ity/hazard map available GIS software expertise No software or trained staff GIS software available and GIS software and experienced experience with simple GIS staff analysis Landslide records No landslide records Some landslide records kept Comprehensive, geo-refer- separately by different enced landslide records agencies in different formats integrated and accessible for different purposes across multiple agencies Vulnerability data availability No data on community Data on proxies for vulnerabil- Vulnerability assessment vulnerability ity (e.g., census data for methods and data established calculating poverty indicators) Project safeguards Documented safeguards need Documents exist for some Documented safeguards to be located; no previous safeguards available from all relevant experience in interpreting and agencies operating safeguard policies CAPACITY LEVEL HOW TO ADAPT THE BLUEPRINT 1: Use this chapter Unless outside GIS expertise and data can be obtained, the community selection process should be based in depth and as a on reports and local knowledge (word of mouth) of landslide-prone areas and vulnerable communities. The catalyst to secure output will be a refined list of communities based on qualitative information sources only. The MCU needs support from to strengthen its capacity for community selection; this might involve the following: other agencies as • Using this book/chapter to gain an understanding of types of available community selection methods appropriate • Identifying colleagues in government or higher education with knowledge of landslides and community vulnerability assessment and considering their appointment as the lead investigator in the community selection process • Working with local commercial or higher education partners to access digital maps or GIS expertise 2: Some elements It might be possible to use GIS data to indicate relative risk across a wide area; this can be refined with local of this chapter knowledge. The expected output at this level will be a low-resolution risk map and a list of priority will reflect current communities. The MCU has strength in some areas, but not all. Elements that are perceived to be Level 1 practice; read the need to be addressed as above. Elements that are Level 2 will need to be strengthened, such as the remaining following: elements in depth • Receiving assistance or training in the use and application of GIS software and use them to further strengthen • Integrating such data and knowledge across ministries capacity 3: Use this chapter The MCU can likely produce and implement community selection using existing capacity. Detailed GIS- as a checklist based landslide risk mapping is possible without any additional training and can be refined with data on past landslides. The expected output will be a high-resolution landslide risk map and a community short list verified through field visits. The following would nonetheless be good practice: • Document the community selection methodology for future reference • Establish a landslide risk database and risk management planning tool CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 33 4.3.1 Approaches to comparing levels of causal factors and identifying zones of rela- landslide risk at multiple locations tive landslide susceptibility • Probabilistic methods (based on landslide The community selection process is founded inventories) for determining the likelihood on data acquisition and analysis involving a of landslide occurrence derived from previ- combination of fieldwork and computer-based ous events work to obtain a relative ranking of landslide risk. The aim is to undertake an appropriate • Bivariate and multivariate statistical form of landslide risk assessment to identify approaches (also requiring historical land- the communities with the highest risk. Two slide data) for indirectly identifying land- possible approaches to this risk assessment slide causal factors task are introduced below. The exact form the • Deterministic spatially distributed mod- landslide risk assessment will take depends on eling of physical slope stability processes local capacity and data. Sections 4.4–4.6 pro- (this is not the same as using site-specific vide greater information on the specific land- models such as CHASM [Combined Hydrol- slide hazard, vulnerability, and risk assessment ogy and Slope Stability Model], section 3.6). methods associated with these two approaches. GIS may also be used to determine the Field reconnaissance and risk ranking exposure of different elements (people, A low-tech approach to landslide risk compari- houses, public buildings, utilities, etc.) to the son among communities is to undertake a landslide hazard and to assess the physical, qualitative assessment of the relative hazard economic, and social vulnerability of these ele- and vulnerability of an existing list of commu- ments. Sources of information on exposure nities using rapid field reconnaissance meth- and vulnerability include land-use maps, maps ods. This approach entails having a team of of land and asset values, and geo-referenced landslide experts, engineers, or geotechnicians, census data containing socioeconomic infor- and vulnerability assessment experts visit each mation. community on the list. This team describes Table 4.1 indicates the main types of spa- landslide hazard, exposure, vulnerability, and tially distributed data that may be used to risk in relative terms or by using a numerical assess and map landslide risk at different spa- scoring system. An inventory of hazardous tial scales—from information on past land- slopes is thus established, and the relative land- slides, to environmental and triggering factors, slide risk to communities can be ranked. to data relating to elements at risk. In many cases, comprehensive data on past landslides Digital data and GIS analysis may not be available or may relate to types of landslide hazard not relevant to MoSSaiC A more technically demanding approach (such as rock falls or debris flows). Similarly, involves using digital spatial data and GIS. not all the environmental and triggering fac- This approach can be useful when there are tors and elements at risk in this table will nec- too many communities for field reconnais- essarily be applicable (such as lithology, seis- sance to be practical, and/or where is little mic data, and transportation network maps). prior knowledge about which communities If hazard, exposure, vulnerability, and risk are affected by landslides. If the digital spatial mapping exercises have been previously data are of sufficient quality, large areas can be undertaken as part of another study or project, assessed using this approach. it may be appropriate to incorporate such There are four main classes of GIS-based maps into the community selection process. landslide hazard assessment: Review these maps to confirm that they have a • Heuristic (expert-based) methods for com- sound basis and take into account the land- bining digital maps of potential landslide slide hazard types relevant to MoSSaiC. 1 3 4    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S TAB L E 4.1  Schematic representation of the basic data sets for landslide susceptibility, hazard, and risk assessment RISK IDEAL UPDATE DATA SCALEb HAZARD MODELc METHODd FREQUENCY (YEARS) Main type Layer 10......1......0.002(DAY) RSa S M L D H S D P S Q Landslide inventory Landslide Landslide activity inventory Landslide monitoring Requires results of heuristic, statistical, or deterministic hazard analysis Digital elevation model Slope angle/aspects, etc. Requires results of probabilistic hazard analysis Internal relief Flow accumulation Lithology Structure Environmental Faults factors Soil types Soil depth Slope hydrology Main geomorphology units Detailed geomorphology units Land-use types Land-use changes Rainfall Triggering Temperature/evapotranspiration factors Earthquake catalogues Ground acceleration Buildings Transportation networks Lifelines Elements at Essential facilities risk Population data Agriculture data Economic data Ecological data Source: van Westen, Castellanos Abella, and Sekhar 2008. Note:  = critical;  = highly important;  = moderately important;  = less important;  = not relevant. a. Usefulness of remote sensing for acquisition of data. b. Importance of the data layer at small (S), medium (M), large (L), or detailed (D) scales, related to feasibility of obtaining data at that particular site. c. Importance of the data set for heuristic (H), statistical (S), deterministic (D), or probablistic (P) models. d. Importance of the data layer for (semi-)quantitative (S) or qualitative (Q) vulnerability and risk analysis. Choosing a risk comparison approach more detailed descriptions of specific meth- ods and data requirements. The chosen Be pragmatic when deciding which approach method should be to use for analyzing and comparing land- slide risk among communities. Use this sec- • not overly ambitious—requiring skills, tion to identify the general data require- software, data, and time far beyond the ments for different approaches to landslide reasonable capacity of the government risk assessment. Sections 4.4–4.6 provide task teams; CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 3 5 • designed to provide enough information for If there is no regular use of wide-area data the purpose of the project, but not necessar- for landslide risk mapping, or if there is already ily a comprehensive quantitative analysis a long list of communities requesting help, of risk—in many cases, decision makers will then a bottom-up or list-driven approach may simply need a screening process for identi- be appropriate. This approach could be vul- fying and prioritizing communities; and nerable to political agendas to include certain communities on the list. On the other hand, • rigorous, in that, regardless of the govern- experienced users of wide-area digital maps ment’s technical capacity, there should be a and GIS software might formulate questions transparent method for community selec- in a top-down manner to derive a list of com- tion that provides the basis for justifying munities. Such an approach is perhaps more selections. politically objective, but requires considerable technical expertise and a good data set. In real- 4.3.2 Methods for community selection ity, a combination of the two methods may be To create an integrated community selection used to confirm the communities on the list. process, combine the chosen landslide risk • Example 1: A priori list-driven questions assessment approach with project-specific for bottom-up selection criteria for selecting communities. When choosing the landslide risk assess- 1. Where have landslides already occurred? ment approach and defining the community 2. How many houses are exposed, and is selection criteria, take the following influences housing density moderate to high? into account: 3. Are the exposed households physically • Obligations under the funding loan or grant and socioeconomically vulnerable? contracts to work in specific locations or meet certain criteria and safeguards 4. Based on the above, which communities are at greatest risk from landslides? • Community-driven demands for solutions to landslide issues 5. Would an intervention be cost-effective, and does it fit the project scope? • Scientific/technical interest in using cer- tain risk assessment methods • Example 2: GIS-based approach for wide- • Awareness and availability (or lack thereof ) area or top-down selection of digital data, GIS, or mapping methods 1. Where are the areas with the highest • Political agendas landslide susceptibility or hazard? Selection criteria 2. Within these landslide areas, where are the most-exposed communities? Begin by defining the questions that, when 3. Within these exposed communities, answered, will become the selection criteria. where is the greatest physical and socio- Each country will ask these questions and economic vulnerability? define their criteria differently depending on their expertise, priorities, and approach to 4. Based on the above, which communities the task. However, two broad criteria for are at greatest risk from landslides? community selection should always be met: 5. Where would an intervention be most the high level of landslide risk to a commu- cost-effective and appropriate? nity (hazard, exposure, and vulnerability) relative to other communities, and the appro- Figure 4.1 illustrates how these two types of priateness of MoSSaiC as a means of address- approach may be used individually or in con- ing that risk. junction. 1 3 6    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S FI G U R E 4.1  Top-down and bottom-up community selection methods Assessment Method: Top-down national search Method: Bottom-up local search criteria (wide area/GIS based) (list driven/reconnaisance based) Hazard Map of landslide susceptibility or Question: Where have landslides hazard zonation based on already occurred? • slope angle • Known landslides • soil types • Areas of slope instability • drainage density • Suspected future landslides • topography • Occurring during or after rain • previous rotational/translational • In soils not rock rainfall-triggered landslides • Rotational or translational Exposure Map of locations of houses and Question: How many houses are density of settlements showing affected, and is housing density • house locations or footprints moderate to high? • housing density and clustering • More than 10 houses in potential (footprint area of houses as a landslide area proportion of the ground • Houses clustered in potential surface) landslide area (housing density • population density comprising > 30% land cover) Vulnerability Map of socioeconomic Question: Are the affected vulnerability showing households low income? • settlement type (authorized, • Wooden or small concrete unauthorized, squatter) houses on small plots • building type (concrete/ • Lack of infrastructure (metaled wooden, high/low rise, etc.) paths/roads, drainage, lighting, • poverty (indicators, proxies) etc.) • High unemployment Landslide risk Create national list and refine Confirm top-down search and/or to communities using bottom-up local search create community short list MoSSaiC interventions involve the con- Regardless of the precise wording of the struction of strategically aligned networks of selection criteria, the aim should be to assess surface water drains. Thus, the greater the landslide susceptibility/hazard, the exposure housing density within the drainage network and vulnerability of communities to that haz- area, the greater the cost-effectiveness will be ard, the overall landslide risk, and the appro- in terms of the number of households benefit- priateness of MoSSaiC. Project-specific crite- ing from the intervention. To estimate the ria may be used to refine and prioritize the cost-effectiveness of a MoSSaiC intervention, community short list. take into account the number and density of Data sources and methods of analysis houses exposed to the landslide hazard as well as the potential damage and costs that could be Once the general landslide risk assessment avoided by reducing the likelihood of landslide approach and community selection criteria occurrence. Other cost factors to take into have been identified, consider the specific account might relate to the potential cost of sources of information that could help answer construction at that location (determined by these questions. Confirm how the information factors such as transportation of materials and will be analyzed—whether by simple qualita- ease of excavating slope material). tive field reconnaissance methods for ranking CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 37 or scoring landslide risk in communities or data, the more comprehensive the landslide with qualitative, semi-quantitative, or quanti- risk assessment will be. However, it is not tative methods using digital maps and GIS expected or required that every country have software. the complete suite of data listed here. Table 4.2 provides a wide-ranging, although Agreeing on the community selection process not exhaustive, list of potential data and analy- sis methods. Generally, the more data sources Each step in the community selection process and the better the quality and analysis of the should be defined and agreed upon by the TAB L E 4.2  Framework of potential data and analysis methods FORMAT POSSIBLE ANALYSIS METHOD INFORMATION SOURCE (LIST/HEURISTIC TO DIGITAL MAP) (QUALITATIVE TO QUANTITATIVE) Prior list of communities requesting assistance Residents reporting problems to List Qualitative assessment government Government ministers or agencies List Qualitative assessment reporting problems Landslide susceptibility and hazard assessment List Qualitative assessment Hard-copy map/aerial photos Qualitative assessment Records of previous landslide locations Digital map Incorporate within GIS-based qualitative or semi-quantitative landslide susceptibility or hazard analysis Local expert knowledge Qualitative assessment Wide-area landslide preparatory Hard-copy map Qualitative assessment factors (slope angles, soil types, land Digital map GIS-based: landslide susceptibility analysis use, drainage, etc.) GIS plus infinite slope model: quantitative hazard analysis Expert observations Expert-based qualitative or semi-quantita- Site-specific slope data and landslide tive hazard assessment expert or engineera Physical parameters Physics-based modeling (quantitative) Exposure and vulnerability assessment Site visits by community officer and Qualitative assessment Exposure: housing type and density engineera information Aerial photos and land-use maps Qualitative assessment Landownership maps Semi-quantitative assessment Site visits by engineera Qualitative assessment Physical vulnerability of elements at Records of previous damage Semi-quantitative assessment risk to damage by landslide Value of elements at risk Quantitative assessment Site visit by social scientist or community Qualitative assessment officera Census data Semi-quantitative or quantitative assess- ment of poverty Socioeconomic vulnerability Geo-referenced census data GIS-based semi-quantitative or quantita- tive assessment of poverty Poverty survey Various methods Geo-referenced poverty survey Map directly in GIS a. These data may be collected in the field as part of the community short list review or to confirm a wider landslide risk assessment. 1 3 8    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S MCU. The timeline, roles, and responsibilities indicate areas of relative landslide for undertaking the analysis should then be susceptibility, exposure, vulnera- set. bility, and risk (undertaken by GIS For the examples given above, the main technicians and engineers/geo- steps in the community selection process technicians) or could be defined as follows. b. Using advanced quantitative GIS • Example 1: A priori list-driven process for map analysis in conjunction with bottom-up selection spatially distributed numerical slope stability models to quantify —— Main data format: Soft data comprising landslide hazard, exposure, vul- lists of known landslide hotspots and nerability, and risk affecting differ- areas of concern (requiring input from ent areas (requiring experienced engineers, field technicians, community GIS analysts and specialists in development officers, census officers) numerical landslide modeling) —— Main steps: 2. Compare the results obtained with an 1. Conduct reconnaissance of listed com- ex ante list of at-risk communities, or munities, completing slope inventory generate a new list. forms to capture landslide hazard, 3. Confirm the community short list and exposure, and vulnerability factors. priorities for intervention using field- 2. Rank landslide hazard, exposure, and based reconnaissance methods as per vulnerability qualitatively using terms Example 1, based on expert judgment. such as low, medium, or high; or use a Agree on the method by which relative numerical scoring system. landslide risk will be assessed, then agree on 3. Confirm rankings using any available any further criteria for community selection. secondary sources of hazard data Such criteria should answer questions relating (knowledge of previous slides, aerial to whether a MoSSaiC-type intervention photos, maps relating to slope fea- would be appropriate, whether it would fit the tures), exposure (housing density and project scope or specific requirements from construction type), and vulnerability funders or the government, and whether it information (poverty surveys, census would be cost-effective. To make the decision- data). making process transparent, these criteria should be set before generating the prioritized 4. Prioritize communities on basis of list of communities. risk ranking or score. Once the list of eligible communities has • Example 2: GIS-based process for wide- been generated and confirmed via brief area or top-down selection reconnaissance of the sites, the task teams will need to carry out detailed mapping in —— Main data format: Digital spatial data each community to identify the specific relating to landslide preparatory and causes of landslides. These specific slope pro- triggering factors, past landslides, and cesses cannot be identified remotely from exposure/vulnerability of communities maps since they typically occur on scales of —— Main steps: 1–10 m, and are affected by human activity (construction, farming, etc.). The detailed 1. Conduct GIS analysis of landslide community-based mapping method is the risk: subject of chapter 5 and is the basis for the a. Using basic semi-quantitative GIS design of the physical landslide risk reduc- map analysis and index overlay to tion measures in chapter 6. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 3 9 4.3.3 Roles and responsibilities in Task teams community selection Members of the landslide hazard assessment and engineering team, mapping team, commu- The community selection process encom- nity liaison team, and technical support team passes a wide range of disciplines and stake- may all be involved in landslide risk data holder interests. Use the following overviews acquisition and analysis. Typical tasks include of roles and responsibilities to ensure the pro- the following: cess is scientifically grounded, rigorous, and transparent. • Review the data acquired and handle pre- liminary error checking MoSSaiC core unit • Process data into appropriate formats The MCU has the following responsibilities: • Conduct field reconnaissance or data analy- • Agree on the process for community selec- sis to determine landslide hazard, and the tion, who will be involved in decision mak- exposure and vulnerability of communities ing, and how the process will be run • Combine the results of hazard and vulner- • Agree on the criteria or thresholds for ability assessments to determine overall inclusion of communities landslide risk • Identify a lead investigator for the task of • Present the risk comparison results in a for- landslide risk data acquisition and analy- mat that is accessible for decision-making sis purposes • Ensure that existing government proce- • Maintain and update hazard, exposure, vul- dures and protocols are followed (e.g., with nerability, and risk data for future use (if regard to access to and sharing of sensitive required as part of the project) data) • For selected communities, generate base • Review the outcomes of the data acquisi- maps for use in detailed community-based tion and landslide risk analysis process landslide hazard and drainage mapping • Agree on a prioritized list of communities (see chapter 5) for detailed mapping and MoSSaiC proj- ects. 4.4 LANDSLIDE SUSCEPTIBILITY For the purposes of community selection, AND HAZARD ASSESSMENT the MCU could be augmented to include land- METHODS slide risk assessment experts from local higher education institutions, and representatives Different approaches can be used to assess from ministries and agencies responsible for relative landslide susceptibility or hazard utilities (water, electricity) and census data. depending on the data, expertise, and These stakeholders should perform the fol- resources available (see above and sec- lowing: tion  3.4). Following is a brief overview of • Advise on the technical aspects of landslide some commonly used assessment methods; risk assessment these are presented in order of increasing data requirements, complexity, and level of • Provide data held by their institutions or quantification: ministries • Field-based reconnaissance and heuristic • Advise on the reliability of data (expert) ranking/scoring of landslide haz- • Contribute to the decision-making process ard (qualitative results at a detailed scale) 1 4 0    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S • GIS-based index overlay of digital maps 4.4.1 Qualitative landslide hazard using a heuristic approach to give landslide assessment: Field reconnaissance and susceptibility (qualitative results over hazard ranking methods medium to regional scales) Qualitative slope stability assessment methods • GIS-based landslide susceptibility and involve the systematic classification of slopes hazard assessment using probabilistic, sta- in relative terms such as high, medium, or low tistical, or deterministic methods (semi- landslide hazard or using a relative rating quantitative and quantitative results par- derived from a numerical scoring system. ticularly suited to large and medium These methods are usually based on a combi- scales). nation of expert judgment and empirical evi- Regardless of whether a simple qualitative dence (local knowledge or records of past or in-depth quantitative method is used, it is landslides). They can be used as a means of important to distinguish between landslide initial assessment of slope stability in the field susceptibility and landslide hazard: or in combination with remote sensing, GIS, and mapping methods. • Landslide susceptibility relates to the type Field reconnaissance and hazard ranking and spatial distribution of existing or poten- methods can be used for community selection tial landslides in an area. Susceptibility in one of two ways: assessment is based on the qualitative or quantitative assessment of the role of pre- • As the primary method in a bottom-up (list- paratory factors in determining the relative driven) approach, where communities have stability of different slopes or zones. The been listed by government agencies and/or magnitude and velocity of existing or poten- community representatives as requiring tial landslides may be taken into account, assistance, and where there are insufficient but the frequency or timing will not be digital map data for a top-down/wide-area specified. assessment of landslide susceptibility or hazard • Landslide hazard is the probability of a landslide (qualitatively or quantitatively • As the second stage in a top-down approach, assessed) of a certain type, magnitude, and as a means of verifying and prioritizing the velocity occurring at a specific location. communities identified via wide-area GIS- Quantitative hazard assessment takes into based susceptibility or hazard mapping. account the role of the triggering event (of a known probability) causing the landslide. Similar methods are used for detailed com- munity-based slope feature mapping once a A comprehensive list of all the potential community has been selected for a MoSSaiC data on environmental factors related to slope intervention. This in-depth mapping process stability is given in table 4.3. The relevance of is fully described in chapter 5. these data to landslide susceptibility and haz- These methods are usually applied in com- ard assessment is described, and their applica- bination with an assessment of the exposure bility at different scales is indicated. It is not and vulnerability of the elements at risk (see expected that all of these data are available section 4.5) in order to arrive at an overall for—or even relevant to—the community landslide risk rating (section 4.6). Field recon- selection process. naissance and hazard ranking methods are Most of the methods introduced in this sec- also used in the development of a national tion can be applied to both landslide suscepti- slope stability database (or risk register) for bility and landslide hazard assessment; the use in landslide management. main difference is whether the landslide prob- One limitation of this type of approach is ability is estimated for a specific location. the difficultly in achieving consistent evalua- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 4 1 TAB L E 4. 3  Overview of environmental factors and their relevance to landslide susceptibility and hazard assessment DATA LAYER AND SCALE OF ANALYSIS GROUP TYPE RELEVANCE R M L D Slope gradient Most important factor in gravitational movements Slope direction Might reflect differences in soil moisture and vegetation Digital Slope length/shape Indicator for slope hydrology elevation Flow direction Used in slope hydrological modeling models Flow accumulation Used in slope hydrological modeling Internal relief Used in small-scale assessment as indicator for type of terrain Drainage density Used in small-scale assessment as indicator for type of terrain Rock types Lithological map based on engineering characteristics rather than stratigraphic classification Weathering Depth of weathering profile is an important factor for landslides Discontinuities Discontinuity sets and characteristics for rock slides Geology Structural aspects Geological structure in relation with slope angle and direction is relevant for predicting rock slides Faults Distance from active faults or width of fault zones is important factor for predictive mapping Soil types Engineering soil types, based on genetic or geotechnical classification Soil depth Soil depth based on boreholes, geophysics and outcrops, is crucial data layer in stability analysis Soils Geotechnical Grain size distribution, cohesion, friction angle, and bulk density are properties crucial parameters for slope stability analysis Hydrological Pore volume, saturated conductivity, PF curve are main parameters properties used in groundwater modeling Water table Spatially and temporal varying depth to groundwater table Soil moisture Spatially and temporal varying soil moisture content main component in stability analysis Hydrology Hydrologic Interception, evapotranspiration, through fall, overland flow, components infiltration, percolation, etc. Stream network Buffer zones around first-order streams, or buffers around eroding rivers Physiographic units Gives a first subdivision of terrain in zones, which is relevant for small- scale mapping Terrain mapping Homogeneous with respect to lithology, morphography, and Geomor- units processes phology Geomorphological Genetic classification of main landform building processes units Geomorphological Geomorphological subdivision of the terrain in smallest units, also (sub)units called slope facets Land-use map Type of land use/land cover is a main component in stability analysis Land-use changes Temporal varying land use/land cover main component in stability analysis Vegetation Vegetation type, canopy cover, rooting depths, root cohesion, characteristics weight, etc. Land use Roads Buffers around roads in sloping areas with road cuts often used as factor maps Buildings Areas with slope cuts made for building construction are sometimes used as factor maps Source: van Westen, Castellanos Abella, and Sekhar 2008. Note: R = regional; M = medium; L = large; D = detailed;  = highly applicable;  = moderately applicable;  = less applicable. 1 42    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S tions of landslide hazard. Different practitio- from such an event (see section 4.5 on vul- ners will inevitably make different judgments nerability assessment). of the same slope and will rank hazards differ- 3. Record observations consistently and ently across wide areas. In several countries, clearly, using a slope reconnaissance form numerical scoring systems have been devel- designed for this purpose. Sketch or take oped to enable even relatively inexperienced photos of key slope features and, if the data engineers and geologists to carry out consis- are to be added to a digital map, use a hand- tent and repeatable slope assessments. Exam- held global positioning system (GPS) ples of numerical scoring systems are receiver to record their location. At this described at the end of this subsection. stage, detailed mapping of the community General procedure for field reconnaissance of or measurement of slope parameters is not landslide hazard necessary; this will be carried out if the community is selected for a landslide miti- 1. Obtain any existing maps of the area and gation intervention (see chapter 5). secure permission to access the site if nec- 4. Make a judgment as to the level of landslide essary. Traverse the area on foot (figure 4.2) susceptibility—high, medium, low—and the and identify any features that indicate a likelihood of the occurrence of the hazard, landslide hazard. Consider slope angle, or use a numerical scoring system to derive material type and properties (soil forma- a hazard score. Different methods for doing tion, weathering and strength, permeabil- this are described below. ity), slope hydrology and drainage (conver- gence zones, drainage routes), vegetation, Frameworks for ranking landslide hazard loading, and existing or past landslides (as Due to the inherent subjectivity of qualitative described in chapter 3). methods, it is important to make the slope 2. Identify any elements exposed to the poten- assessment process as transparent as possible tial or existing landslide hazard and deter- by recording observations and the basis for mine their vulnerability (degree of damage) judgments clearly and systematically. Basic forms simply act as a record of observations; more sophisticated methods allow different FI G U R E 4.2  Field reconnaissance slope features to be numerically scored on the basis of their likely contribution to slope sta- bility/instability. A standard slope reconnais- sance form should be developed for this pur- pose (table 4.4). It could be adapted from existing forms used in other countries. Once the slope features have been recorded in the agreed-upon format, landslide hazard should be assessed in terms of potential land- slide type, likelihood, and magnitude. The likelihood of a landslide is usually described in terms of the expected frequency or return period, or in qualitative terms with respect to other slopes. An example of a landslide likeli- hood rating system is given in table 4.5. The magnitude of the potential landslide consists of at least two components: an esti- mate of the potential size of the failed area (or volume of ground displaced; see the following CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 43 TA BLE 4 .4  Typical sections of a slope reconnaissance form SLOPE FEATURE DESCRIPTION Slope angle • Gently sloping (< 15°) to very steep (> 45°) Topography • Concave/convex/planar/hummocky/complex/terraced Slope-forming • Degree of weathering as indicator of strength (from bedrock to residual soils and material colluvium) • Depth of soil to bedrock Erosion • Type: indistinct/rill/gully/piping/washout • Extent: isolated or small areas/multiple features/almost continuous area Geological • Outcropping of bedrock features • Presence of joints • Joint spacing: wide (massive)/medium (blocky)/close (fractured) Ground • Extent: isolated/substantial moisture • Location: base of slope/midslope/convergence zone/strata interface/other • Occurrence: only after rainy/wet season/all year Seepage • Extent: isolated/substantial • Location: bedding planes/joints/shear zone/strata interface/other • Water: clear/muddy Vegetation • Type (%): grass/shrub/forested/cultivated/other • Density: sparse/moderate/dense Site stability • Known: past landslide activity/landslide-prone area • Indicators: tilting of trees or structures/hummocky ground/tension cracks/other Adverse human • Slope excavation/loading/removal of vegetation/irrigation/mining/water leakage/ impact drainage failure Sketch • Slope cross-section indicating geometry, strata, geological features, seepage, ground moisture, vegetation, site stability indicators, adverse human impacts, and location of any elements at risk • Slope plan indicating the above features and location of previous landslides Landslide • Landslide type: fall/topple/slide/flow/complex hazard • Slope material: bedrock/unconsolidated material (see chapter 3) • Landslide likelihood (see table 4.5) • Landslide magnitude: estimate size of potential failure and potential distance of runout (Finlay, Mostyn, and Fell 1999) • Hazard score (if using numerical scoring system) equation given by Cruden and Varnes 1996), W = Maximum width between flanks of land- and some description of what will happen to slide perpendicular to length, L the failed material such as the distance/depth/ L = Minimum distance from landslide crown speed/volume of runout. to toe Volume of ground displaced = 1/6π × D × W × L Empirical methods for estimating the travel distance and depth of failed material require Where: few measurable parameters. If the landslide D = Maximum depth to slip surface below type is properly identified and the relevant original ground surface equations used, Wong and Ho (1996, 419) 1 4 4    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S TAB L E 4.5  Example of a landslide likelihood rating system INDICATIVE TOTAL ANNUAL HAZARD SCORE DESCRIPTION OF LIKELIHOOD PROBABILITY LEVEL The event is expected to occur and may be triggered 5 0.5 Very high by conditions expected within a 2-year period The event is expected to occur and may be triggered 4 0.5–0.2 High by conditions expected within a 2- to 5-year period The event will probably occur under adverse conditions 3 0.2–0.02 Moderate expected over a 5- to 50-year period The event could possibly occur under adverse 2 0.02–0.002 Low conditions expected over a 50- to 500-year period The event is unlikely to occur except under very 1 0.002–0.0002 Very low adverse circumstances over a 500- to 5,000-year period Source: Indicative measures of landslide hazard based on Australian Geomechanics Society 2000 and Ko Ko, Flentje, and Chowdhury 2004. assert that such an approach provides a “quick nities in developing countries. However, three and realistic assessment of the likely range” of case studies are presented below to exemplify runout distances and depths. An approach the general principles of this class of slope sta- such as that by Finlay, Mostyn, and Fell (1999) bility assessment. These principles are as fol- requires three parameters that can be readily lows: estimated in the field or modeled: initial slope • The aim of the field study should be clearly angle, the maximum depth to the potential slip defined, primarily so as to develop a priori- surface, and the height of the landslide crest tized list of slopes in specific communities above the base of the slope. See section 3.3.2 for a definition of these landslide features. but also potentially to lead to the establish- If a numerical scoring system has been ment of a national database of slopes, used, the values for landslide likelihood and observed landslides, and slope stabilization magnitude should be summed to give a total works. hazard score. Otherwise, the level of hazard • The data requirements and assessment should be described relative to other slopes method should be tailored to local condi- using terms such as high, moderate, or low, tions (slope types, landslide types, local and provide the rationale for their assessment. knowledge of landslides). Once community vulnerability to landslides has been assessed (section 4.5), the hazard • The assessment method should be formal- score or ranking is combined with the vulner- ized to enable the training of field techni- ability score or ranking to provide an indica- cians and the consistency of data collection tion of the overall landslide risk posed to each across field teams and over time. community. The following three case studies exemplify- Examples ing these principles are drawn from Hong Kong SAR, China; Australia; and the United The details of site-specific slope assessment States. methods and resulting slope inventories are rarely published by governments. In particu- • Example 1: Geotechnical Engineering lar, there do not appear to be examples of sys- Office, Hong Kong SAR, China. Hong Kong tematic field-based methods for qualitative SAR, China, is a world leader in terms of its assessment of slope stability in urban commu- establishment of a comprehensive slope CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 4 5 and landslide database, the assessment of Liang (2007) provides a helpful review of landslide hazard and risk, and management several of these methods, and of the slope of manmade and natural slopes. The New management framework developed in Priority Ranking System is used for assess- Hong Kong SAR, China (see above). ment of soil cut slopes, rock cut slopes, Included in the report’s appendixes are retaining walls, and fill slopes. For each landslide hazard reconnaissance forms slope type, a field team records the detailed used by the Ohio Department of Transpor- slope geometry, exposed slope materials, tation. While not directly applicable to slope protection and drainage, signs of urban landslides in developing countries, instability, engineering judgment as to the this report demonstrates the principles of hazard posed, and the location of facilities site-based assessment of slopes and the use (buildings and roads) with respect to the of this information in prioritizing expendi- slope. Technicians and engineers use com- ture on landslide risk reduction. putation sheets to assign numeric scores to each slope characteristic and derive insta- 4.4.2 Qualitative landslide susceptibility bility and consequence scores. Slopes can mapping: GIS index overlay methods then be prioritized for remediation mea- sures, maintenance, or monitoring (Cheng The stability of a slope is related to environ- 2009). mental factors such as slope angle, topogra- phy, drainage (on the surface and in the • Example 2: University of Wollongong, ground), soil type, geological characteristics, Australia. Ko Ko, Flentje, and Chowdhury land use, and vegetation cover. In many coun- (2004) report on a method for assessing the tries, there are digitized maps of these envi- stability of four classes of slopes: natural ronmental factors available at small (regional) slopes, embankments, rock slopes or rock scales of 1:250,000 to 1:100,000, medium cuttings, and soil cuttings. They include a scales of 1:50,000 to 1:25,000, and—some- sample field data sheet for recording the times—at large scales of 1:10,000. If GIS soft- characteristics of natural slopes and assign- ware and expertise are also available, it is pos- ing numeric scores to describe their influ- sible to analyze digital maps and produce ence on landslide hazard. Five categories of landslide susceptibility, hazard, or risk maps relative hazard are defined (from very high at these scales. The four main classes of GIS- to very low) which relate to the total score. based landslide assessment are heuristic A nominal landslide probability is then (expert-based), probabilistic, statistical, and identified based on the score and expert deterministic. judgment. This hazard rating can then be This subsection outlines the basic princi- combined with a consequence (vulnerabil- ples of GIS-based heuristic landslide suscepti- ity) score (also described in the paper) to bility mapping methods and presents related give an indication of the relative landslide case studies. These methods are closely related risk associated with a particular slope. The to the numerical scoring approach often used authors conclude that, by using this method, in field reconnaissance in that scores (an the careful observation and expert judg- index) are assigned to different slope, soil, ment of slope characteristics can provide a geology, drainage, and land cover characteris- rapid means for prioritizing slopes for more tics. These layers are then overlaid, and the detailed landslide assessment and risk influence of the various environmental factors reduction. weighted to reflect their importance in deter- • Example 3: U.S. Federal Highway Admin- mining slope stability. This procedure is com- istration. Several U.S. states have devel- monly called index-overlay analysis. GIS map- oped field-based slope assessment methods ping approaches enable the assessment of focusing on the risk to roads and road users. slope stability over continuous large areas, 1 4 6    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S rather than just considering individual sites. these are not reviewed here, as they can Because the GIS environment allows many represent a significant financial or time layers of information to be added, a landslide investment which may not be within the susceptibility/hazard map can be added to a scope of the project. vulnerability map to derive an overall risk 2. Convert the digital data layers into the cor- map. rect format for the chosen GIS platform. It With heuristic mapping approaches, may be necessary to geo-reference, trans- expert knowledge of the local environmental form, or reproject the data so that all the factors for landslides is essential. Ideally, if layers are in the same coordinate system the locations and types of previous landslides and geographical projection. Verify the are known and mapped, this information can accuracy and completeness of the data, and be used directly to derive appropriate weights make any necessary corrections. for the different environmental factors on each layer of the landslide hazard map. In 3. Use the elevation data to generate a digital many countries, a record of landslides is not elevation model in raster or vector format always kept or may be incomplete. In the (grid-based or triangular irregular net- absence of a landslide inventory, the analyst work). Use tools within the GIS environ- must apply local knowledge and expert judg- ment to derive key slope stability factors ment in assigning weights to the various envi- from the digital elevation model such as ronmental factors. This results in a qualita- slope angle, aspect, and length; internal tive map indicating relative landslide relief; and drainage routing. susceptibility. 4. Process other map layers to derive useful Limitations of GIS-based approaches are information. Geology maps can be reinter- related to the availability, quality, and scale of preted in terms of engineering geological the digital data and the expertise of the ana- classifications (relating to rock composition lyst. Keep in mind that landslide processes and strength). Soil depths and strengths can tend to be highly localized and cannot usually sometimes be inferred or approximated be captured at the wide-area scale. from maps of soil erosion and soil type. Note that a landslide susceptibility map Despite the importance of soil properties simply identifies the spatial variation of differ- for predicting slope stability, there are often ent ensembles of slope characteristics and very little direct data on soil strength, how landslide prone these slopes are in rela- hydrology, or depth over wide areas. In tion to each other. A landslide hazard map many cases, the limited data on soils will contains more information by indicating both need to be augmented by local knowledge the spatial and temporal likelihood of land- and by verifying soil characteristics at slide occurrence—that is, the location and tim- selected sites. ing of potential landslide events. 5. For each environmental factor, convert the General procedure for GIS index overlay range of values of the data in that layer into 1. Acquire any available digital data relating to an index that describes the relative contri- the environmental factors associated with bution to slope stability. Low index values slope stability, including elevation data (e.g., may be assigned where the characteristic of contour maps), geology, soil, and land-use the environmental variable is associated maps. If important data relating to a partic- with stable slopes (such as a strong soil or ular environmental factor are not available bedrock); high index values indicate an in a digital format but do exist in hard copy, association with less stable slopes (e.g., these may need to be digitized. Numerous weak soils). Index each factor (GIS layer) in field-based and remote-sensing methods this way—from flat land to steep slopes, exist for generating digital spatial data; shallow soils to deep soils, strong soils to CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 47 weak soils, established deep-rooting vege- • Cuba: National Landslide Risk Assess- tation to bare land, and so on. This process ment Project. Cuba is recognized as having is similar to numerical scoring systems a more comprehensive national risk man- applied in slope reconnaissance methods. agement strategy than many other coun- Within each environmental factor or layer, tries in the Caribbean region. However, normalize the index values from 0 to 1. because losses from landslides remain high, in 2004 the National Civil Defense organi- 6. Apply a weighting to each of the normal- zation of Cuba and the Institute of Geology ized indexed layers, and overlay them by and Paleontology initiated a new national combining them to derive an overall land- landslide risk assessment project. In the slide susceptibility map. The higher the total score, the more susceptible the terrain absence of a sufficient national landslide unit or grid cell is to landslides. Use experi- inventory, a qualitative approach was taken: ence and local knowledge to determine the application of spatial multicriteria eval- how important each class of environmental uation techniques, in a GIS environment, to factor is in influencing slope stability and to develop a national landslide risk index map. assign different weights to the layers Castellanos Abella and van Westen (2007) accordingly. Various methods have been report the development and implementa- developed for systematically assigning tion of this approach, which is briefly sum- weights; these include the following: marized below. • Direct methods, based on expert opin- Five landslide susceptibility and five vul- ion and field experience nerability indicators were digitally mapped at a cell size of 90 × 90 m. Each indicator • Pair-wise, using a comparison matrix in was standardized and weighted by experts which each environmental factor is according to its contribution to landslide taken in turn and compared with each susceptibility or vulnerability in order to other factor to assess the most signifi- produce a measure of landslide risk. Three cant contributor to slope stability within weighting methods were used (direct each pair weighting, pair-wise comparison, and rank • Ranking, ordering environmental fac- ordering), and the weights combined to tors according to their expected influ- produce a landslide risk index. The result- ence on slope stability and then normal- ing map is used by local authorities to target izing the ranked list between 0 and 1 high-risk zones that require further detailed landslide investigation so as to identify • Indirect methods, using statistical appropriate landslide risk management methods to give weights based on data strategies (figure 4.3). for previous landslides and the inferred causal factors. • Cuba: Medium-scale qualitative assess- The resulting index overlay map presents ment of landslide susceptibility. A second the relative landslide susceptibility of different helpful example from Cuba is the qualita- terrain units (in the case of vector maps), or tive assessment of landslide susceptibility grid cells (raster maps) at a resolution deter- in San Antonio del Sur, Guantánamo, at a mined by that for the original digital data and scale of 1:50,000. The first stage of the anal- any GIS transformation of that data. ysis was the preparation of a geomorpho- logical map from aerial photos and field- Examples work. The project identified 603 terrain The following examples, both from Cuba, mapping units of homogenous geomorpho- illustrate GIS-based landslide susceptibility logical origin, physiography, lithology, mor- assessment. phometry, and soil type. The resulting 1 4 8    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S FI G U R E 4. 3  Method for developing a national landslide risk index map for Cuba Goal Subgoals Indicators susceptibility hazard conditions slope angle index geology land use triggering factors earthquakes risk index rainfall vulnerability social population index economic production risk evaluation environmental protected areas housing national landslide physical transportation mitigation plan Source: Castellanos Abella and van Westen 2007. insight into local factors contributing to Probabilistic approaches landslides allowed for the development of Probabilistic approaches require a compre- weights for mapping landslide susceptibil- hensive inventory of past landslides—their ity. Again, three weighting methods were location with respect to environmental factors explored—direct weighting, pair-wise com- (topography, geology, soils, drainage, etc.) and parison, and rank ordering. This heuristic their timing with respect to triggering factors identification of local terrain mapping units (such as rainfall events). In many cases, they and related observations on slope also include information on the damage stability,enabled the generation of a qualita- caused, thus allowing the vulnerability of ele- tive landslide susceptibility map at a more ments at risk to be inferred. Some of the best detailed resolution than would have been examples of national landslide databases can possible with the conventional index-over- be found in Canada; Colombia; France; Hong lay method applied at the national scale Kong SAR, China; Italy; and Switzerland. (Castellanos Abella and van Westen 2008). Analysis of these data within a GIS setting 4.4.3 Semi-quantitative and quantitative (and often in combination with heuristic landslide susceptibility and hazard methods) can allow the prediction and map- mapping methods ping of future landslides in terms of mean recurrence interval, landslide density, and The third group of GIS-based landslide hazard exceedence probability. mapping methods are more data intensive and Statistical methods require higher levels of scientific expertise than the qualitative approaches described Statistical methods also require data on past above. Probabilistic, statistical, and determin- landslides—in this case, the role of individual istic modeling methods can provide semi- environmental factors, or combinations of quantitative or quantitative measures of land- factors, in contributing to slope failures is sta- slide hazard that include indicative or tistically evaluated. Thus, landslide suscepti- numerical predictions of landslide probability. bility can be indirectly inferred by applying These methods are briefly introduced here; these causal relationships over wide areas. teams with the requisite level of expertise are Bivariate statistical approaches, such as presumably already familiar with these meth- weights of evidence methods, consider each ods and their data requirements. causal map in turn in order to derive weight- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 4 9 ing values for that environmental factor. deterministic modeling of slope stability. These methods are widely employed in con- These methods are most appropriately applied junction with heuristic methods. Multivari- over small areas, such as river catchments or ate approaches use methods such as logistic subcatchments; and at detailed scales, since regression, artificial neural networks, and they require large amounts of good quality fuzzy logic to determine the relative contri- spatially distributed data relating to topogra- bution of all the causative environmental fac- phy, soil depth and strength, and hydrological tors in determining the landslide hazard for a properties. A digital elevation model is used to defined land unit. determine rainfall and surface water infiltra- Limitations of statistical methods include tion, groundwater levels, and pore water pres- the inherent generalization of landslide caus- sures. A typical distributed deterministic ative factors—the assumption that the same model uses a simple infinite slope stability combination of factors will cause landslides equation in conjunction with the two-dimen- throughout the study area. This limitation is sional hillslope hydrology calculations to magnified if the data on past landslides do not determine the factor of safety for each map- differentiate between landslide types, if the ping unit or grid cell. landslide data are incomplete, or if the envi- Examples of deterministic models include ronmental factor maps are not sufficiently the shallow landsliding model (SHALSTAB) detailed to capture localized variations. developed by Montgomery and Dietrich (1994) and available as an ArcScript for use in Deterministic approaches ArcView GIS; and the Stability Index Mapping Deterministic approaches address landslide (SINMAP) model developed by Pack, Tarbo- hazard in terms of underlying physical pro- ton, and Goodwin (1998), which is also avail- cesses. For engineering and geotechnical able as an ArcView GIS extension. applications, deterministic modeling is usually Figure 4.4 shows the results of such an anal- undertaken at the scale of individual slope ysis for the assessment of debris flow hazard in cross-sections. However, in a GIS environ- Tegucigalpa, Honduras. The spatial data for ment, the ability to represent slope parameters this study by Harp et al. (2009) included a dig- over a wide area allows spatially distributed ital elevation model (for deriving slope angle), F IG U R E 4 .4  Quantitative GIS-based hazard map for Tegucigalpa, Honduras Source: Harp et al. 2009. 1 5 0    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S a geological map (for deriving material The vulnerability of exposed elements is strength), and an inventory of debris flows expressed in terms of the potential degree of triggered by Hurricane Mitch in 1998. An infi- damage (or loss) with respect to the magni- nite slope stability model (based on the limit tude (or intensity) of a given landslide. equilibrium approach described in chapter 3) MoSSaiC projects are intended for the most- was used to predict the slope factor of safety physically and -socioeconomically vulnerable and hence determine the debris flow hazard communities. As with landslide hazard assess- for different hillslopes. ment, the scale of this assessment can vary Deterministic methods can also be applied from regional to detailed household level, and in the prediction of landslide runout—travel the data requirements, methodology, and out- distance, velocity, and depth of landslide puts will vary accordingly. Exposure is often debris. The development and application of considered in conjunction with, or as an inte- such approaches require extensive data and gral part of, vulnerability (Crozier and Glade significant expertise, and are therefore not 2005). necessarily appropriate for use in community Table 4.6 identifies the ways in which the selection. exposure and vulnerability of different ele- ments at risk may be represented at different spatial scales. Of particular relevance to 4.5 ASSESSING COMMUNITY MoSSaiC are data on buildings, population, VULNERABILITY TO and economic factors that describe the physi- LANDSLIDES cal and socioeconomic exposure and vulnera- bility of urban communities to landslides. Having identified the landslide susceptibility At medium mapping scales, the physical or hazard for a list of communities, or on a exposure and vulnerability of the community wider spatial scale using GIS-based methods, can be described simply in terms of how the next stage is to consider what the conse- many buildings (houses) might be affected by quences of a landslide event would be in terms a landslide event. At a more detailed scale, for of the exposure and vulnerability of different a given landslide location and magnitude, the elements (people and property) to that hazard. physical exposure and vulnerability of a The overall landslide risk is the combination house may be described in terms of how eas- of hazard, exposure, and vulnerability. ily it could be damaged. For example, if hit by Exposure describes the location of a par- a small landslide, a concrete house with good ticular element with respect to the potential foundations may be less likely to collapse landslide—whether it is on the upper or side than a wooden structure with poor founda- margins of the slide, within the failed mass, or tions. The physical vulnerability of people in the path of the debris. In selecting commu- within a community relates to the level of nities for potential MoSSaiC interventions, injury or loss of life; this is a very difficult both the number of houses exposed to each aspect of vulnerability to assess since it particular landslide hazard and the density of requires the combined spatial and temporal housing within that hazard zone (often prediction of both the landslide event and the expressed as the proportion of land coverage exposure of people to that event. by houses) must be noted. Housing density is The socioeconomic vulnerability of a com- particularly significant, because MoSSaiC munity to landslides is related to the ability of projects involve the construction of a network households to recover from a landslide. This of surface water drains to improve slope stabil- recovery might involve rebuilding part or all of ity and reduce the hazard to multiple house- a house, replacing possessions, finding a dif- holds. The greater the housing density, the ferent means of income (if tools or stock have more households will benefit from the drain- been lost), or moving to a different location. age intervention. While not synonymous with poverty, socio- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 5 1 TAB L E 4.6  Main elements at risk used in landslide risk assessment studies and their spatial representation at four mapping scales SCALE OF ANALYSIS ELEMENT Small Medium Large Detailed Buildings By municipality Mapping units Building footprint Building footprints • Number of buildings • Predominant land use • Generalized use • Detailed use • Number of buildings • Height • Height • Building types • Building types • Construction types • Quality/age • Foundation Transportation General location of Road and railway All transportation All transportation networks transportation networks networks, with general networks with detailed networks with detailed traffic density informa- classification, including engineering work and tion viaducts, etc., and traffic detailed dynamic traffic data data Lifelines Main power lines Only main networks Detailed networks Detailed networks and • Water supply • Water supply related facilities • Electricity • Wastewater • Water supply • Electricity • Wastewater • Communication • Electricity • Gas • Communication • Gas Essential By municipality As points Individual building Individual building facilities • Number of essential • General characterization footprints footprints facilities • Building as groups • Normal characterization • Detailed characterization • Buildings as groups • Each building separately Population By municipality By ward By mapping unit People per building data • Population density • Population density • Population density • Daytime/nighttime • Gender • Gender • Daytime/nighttime • Gender • Age • Age • Gender • Age • Age • Education Agriculture By municipality By homogeneous unit By cadastral parcel By cadastral parcel, for a data • Crop types • Crop types • Crop types given period • Yield information • Yield information • Crop rotation • Crop type • Yield information • Crop rotation and time • Agricultural buildings • Yield information Economic By region By municipality By mapping unit By building data • Economic production • Economic production • Employment rate • Employment • Import/export • Import/export • Socioeconomic level • Income • Type of economic • Type of economic • Main income types plus • Type of business plus activities activities larger-scale data larger-scale data Ecological Natural protected areas Natural protected area General flora and fauna Detailed flora and fauna data with international approval with national relevance data per cadastral parcel data per cadastral parcel Source: van Westen, Castellanos Abella, and Sekhar 2008. economic vulnerability is often related to the likely to live in landslide-prone areas than level of poverty: poorer households will find it wealthier households, and in houses that are more difficult to recover. In many ways too, less resilient to the physical impact of a land- socioeconomic vulnerability is closely related slide. Poverty assessments can sometimes pro- to the exposure and physical vulnerability of a vide an indication of a community’s vulnera- community since poorer households are more bility. 1 52    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S The following subsections outline two • The number of houses and people likely to broad approaches to assessing the potential be exposed to the landslide and debris consequences of landslides with a view to • The housing density (this helps with the determining which communities have the assessment of the possible cost-effective- greatest exposure and vulnerability. ness of constructing a drainage network) • Field reconnaissance and heuristic (expert- • The potential physical damage to individ- based) ranking/scoring of community and ual houses based on their construction type household exposure and vulnerability to (if there is sufficient knowledge of past landslides landslide impacts and the resilience of • GIS-based methods using land-use maps to structures to such impacts; figure 4.5) determine community exposure, and cen- • The cost of the potential landslide damage sus data to assess vulnerability (qualitative (if the approximate value of the elements at to semi-qualitative results over medium to risk is known). regional scales). Use these guidelines to identify a method- F IGUR E 4 . 5  Resilience of structures ology compatible with available data and depending on construction type expertise, and that can be interfaced with landslide hazard information in terms of its format (list or map) and spatial scale. 4.5.1 Field reconnaissance and vulnerability ranking methods Field reconnaissance and ranking methods were introduced in section 4.4.1 as a means for rapid assessment of landslide hazard by a team of experts. Similar methods can be applied to a. Minor landslide where the impact of the assess community exposure and vulnerabil- debris has damaged a concrete home. ity—either qualitatively (e.g., as high, moder- ate, or low), or quantitatively (using a numeri- cal scoring system). Hazard, exposure, and vulnerability measures can be combined to rank overall landslide risk. General procedure for field reconnaissance of vulnerability Specific procedures relating to the assessment of community exposure and vulnerability to landslide hazards are highlighted here; see section 4.4.1 for the general procedure for field reconnaissance. If a landslide hazard has been identified, the team should have already estimated the spatial extent of the landslide-prone area and the potential downslope extent of the failed material. On the basis of this assessment, esti- b. Minor landslide where the impact of the mate the physical exposure and vulnerability debris has destroyed a wooden home. in terms of the following: CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 5 3 Consider the overall socioeconomic vulner- slope assessment process as transparent as ability of the community using locally relevant possible by recording observations and the indicators such as basis for judgments clearly and systemati- cally. Basic forms can be used to record • the size of houses and plots, house con- observations; more sophisticated tools allow struction type, and ownership of vehicles; different community and household charac- • the presence or absence of basic infrastruc- teristics to be numerically scored on the ture such as publicly supplied piped water, basis of their likely contribution to exposure provisions for sanitation and waste disposal, and vulnerability. The task team should electricity, and paved roads and paths; and develop a standard community reconnais- sance form for this purpose. The typical sec- • evidence of unemployment, low levels of tions of a slope reconnaissance form that educational attainment, overcrowded hous- relate to vulnerability assessment are out- ing, and isolated or marginalized groups lined in table 4.7. (such as the elderly or disabled). Based on these observations, rank physical Semi-quantitative measures of socio- vulnerability to the potential landslide hazard, economic vulnerability (based on census data estimating how much physical damage could or community questionnaires) are outlined in be caused. This can be done either qualita- section 4.5.2; at this stage, on-site application tively (high, moderate, or low), or quantita- of such methods at the household level would tively (from 0 to 1—no loss to total loss), using be time consuming, and may be more appro- a scoring system such as that illustrated in priate once the selection of individual commu- table 4.8. nities has been confirmed. Similarly, for areas of the community potentially exposed to landslide hazard, Frameworks for ranking vulnerability to develop a qualitative or quantitative scoring landslides system to indicate the socioeconomic vulner- Given the inherent subjectivity of qualita- ability. tive methods, it is important to make the TA BLE 4 .7  Typical sections of a slope reconnaissance form that relate to vulnerability assessment VULNERABILITY COMPONENT DESCRIPTION • Number of houses on landslide-prone area Exposure of elements to • Number of houses in potential landslide runout zone landslide hazard • Density of houses exposed to the landslide hazard • Number of houses likely to be lost Physical vulnerability of • Number of houses likely to be significantly damaged elements to landslide hazard • Number of houses likely to need minor repairs • Number of households likely to need relocating Various possible measures including: • Financial resources/level of poverty (quality of housing, ownership of possessions) • Presence/absence of basic infrastructure Socioeconomic vulnerability • Level of unemployment (adults not at work) • Level of education (children not at school) • Level of overcrowded housing • Existence of marginalized groups 1 5 4    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S Data sources TAB L E 4.8  Example of a numerical scoring system for landslide damage to houses At regional and medium scales, the number of buildings per area may be derived from census SCALE OF DISTANCE (m) information or from land-use maps (identify- LANDSLIDE (m3) < 10 10–50 > 50 ing urban or semi-urban residential areas); < 10 2 0.3 0.2 0.1 and at larger scales, individual building foot- 10 –10 2 3 0.4 0.3 0.2 prints may be indicated. Since the most vul- 103–104 0.6 0.5 0.4 nerable communities are often unauthorized > 10 4 1.0 0.9 0.8 or informal settlements, it is likely that maps of Source: Dai, Lee, and Ngai 2002. buildings will be out of date. In such cases, aerial photos may be used supplement this Note: Damage is indicated on a scale of 0 (no loss) to 1 (total loss) depending on landslide scale and information. At the scales required for the proximity. community selection process, the physical vulnerability of communities may simply be 4.5.2 GIS-based mapping methods for derived as the likely number of buildings to be vulnerability assessment affected by a landslide (and assuming equal damage). GIS software is designed for the overlay of dig- For the purpose of community selection it ital spatial data, the analysis of that data, and may be helpful to use poverty as an indicator the generation of combined maps. Thus, if the for comparing the relative socioeconomic vul- location of communities is available as a digital nerability of communities (although it is rec- map, this information can be used in conjunc- ognized that poverty and vulnerability are not tion with landslide susceptibility or hazard synonymous). In many countries, poverty or maps to determine exposure to landslides. The welfare indicators have been derived that use number or density of buildings within these information from surveys or the national cen- landslide zones can be used as a proxy for the sus. Poverty surveys and census data are often physical vulnerability of communities and the geo-referenced to allow mapping of different likely cost-effectiveness of a drainage inter- levels of aggregation such as at the level of vention; the socioeconomic vulnerability (or municipal and enumeration districts. It is resilience) of communities can be represented sometimes possible to map this information at by some form of poverty measure. the community and street-level scales—the Vulnerability may be expressed in qualita- scale of the potential landslide hazard and mit- tive terms (such as high, medium, or low), igation measures. semi-quantitative terms (e.g., using a poverty index), or quantitative terms (such as the Frameworks for assessing poverty number of houses likely to be damaged and the estimated value of the damage). Quantitative The most straightforward poverty measures measures are often used to indicate direct simply consider household income and con- damage, but it is less easy to quantify indirect sumption expenditure as indicators of the damage, such as the social, emotional, long- level of welfare. More sophisticated measures term economic damage to individuals and the incorporate other indicators. For example, wider community. Thus, semi-quantitative Human Development Index (HDI) of the poverty indicators are often used as a proxy for United Nations Development Programme is a vulnerability to direct and indirect damage. composite of income, education, and health It is helpful if the spatial scale and level of measures designed to facilitate comparison of quantification of the vulnerability assessment deprivation and development levels nationally is matched to the scale and output format of and globally. Locally derived poverty indica- the hazard mapping exercise to enable calcu- tors may also be available that have been tai- lation of the overall landslide risk. lored to the specific characteristics of a par- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 5 5 ticular region or country. Table 4.9 illustrates and present either as a list or import into GIS the typical components of a locally derived to create a map. poverty index. These measures can be applied both in the field (using a household questionnaire), or 4.6 ASSESSING LANDSLIDE RISK using GIS (by acquiring geo-referenced cen- AND CONFIRMING sus data at the least aggregated, most detailed, COMMUNITY SELECTION level possible). The required census variables may initially be processed in the census data- Landslide risk is a product of the level of land- base software using available search and slide susceptibility or hazard and the vulnera- query protocols. For more complex analysis, bility of the elements exposed to damage by export the data to a spreadsheet. Finally, sort that hazard (the potential landslide conse- the list of communities according to socio- quences). The previous two sections have out- economic vulnerability (poverty in this case) lined a range of methods for deriving landslide TA BLE 4 .9  Typical components of a locally derived poverty index MAXIMUM ITEM CLASSIFICATION SCORE SCORE FOR ITEM Wall type Brick/block/concrete 3 Wood and concrete 2 3 Wood 1 Wattle/tapia/makeshift 0 Toilet type WC to sewer/cess pit 1 1 Pit latrine/none 0 Light source Electricity/gas 1 1 Kerosene/none 0 Possessions TV, telephone, video, stove, refrigerator, washing 0.5 each machine 4 Car/pick-up 1 No. persons <1 3 per 1–1.99 2 bedroom 3 2–3 1 3.01 or more 0 Education Tertiary/university 5 of head of Secondary complete 4 household Secondary incomplete 3 5 Primary complete 2 Primary incomplete 1 None 0 No. of 1 3 employed to 0.49–1 2 total no. of 3 persons 0.25–0.5 1 < 0.25 0 Maximum total score: 20 Source: Government of St. Lucia 2004. 1 5 6    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S susceptibility or hazard, exposure and vulner- ability in qualitative, semi-quantitative, and TAB LE 4 .10  Example of a risk rating matrix quantitative terms; in list or map-based for- OVERALL PHYSICAL AND SOCIOECONOMIC mats; and using field reconnaissance or GIS HAZARD VULNERABILITY RATING processing of digital spatial data. This section RATING Very high High Medium Low Very low brings these outputs together to derive an Very high 5 5 4 3 2 assessment of landslide risk to enable selec- High 5 4 4 3 2 tion of the most appropriate communities in Medium 4 4 3 2 1 which to initiate MoSSaiC projects. Low 3 3 2 1 1 Very low 2 2 1 1 1 4.6.1 Combining the hazard and vulnerability information Depending on the approach taken for assess- ing landslide hazard, expose and vulnerability, A team of landslide experts/engineers or use one of the following methods to combine geotechnicians and a social scientist or com- these assessments and derive the overall land- munity development practitioner should visit slide risk to communities. each of the short-listed communities and use rapid field reconnaissance to confirm the Field reconnaissance methods selection. Complete the reconnaissance forms and assess the overall landslide risk when on site in each 4.6.2 Confirming selected communities community—assigning both hazard and vul- The task team should present the results of the nerability ratings in qualitative terms or risk comparison and analysis to the MCU according to a numerical scoring system. Com- along with the following information to sup- bine these ratings or scores to give the land- port the decision-making process: slide risk rating using a matrix such as that in • Executive summary table 4.10. Once all the communities on the list have —— A list or table of the communities in rank been visited and assessed in this way, review order of landslide risk together with the the completed reconnaissance forms and rank hazard, exposure, and vulnerability rat- the communities in order of landslide risk. ings or scores (derived from field recon- naissance results or GIS maps) GIS-based methods —— Maps of the landslide hazard, exposure, An alternative to a risk rating matrix is to vulnerability, and risk assessments if GIS overlay GIS-generated hazard and vulnera- methods have been applied bility maps to produce a composite landslide risk map. Different weights may be assigned • Appendixes to the hazard and vulnerability maps accord- —— Supporting materials detailing the data ing to the agreed-upon community selection acquisition and analysis process and pro- criteria. viding the rationale behind qualitative To identify a community short list, review heuristic (expert-based) judgments the attributes of the risk map and sort the com- munities by overall risk. Compare the risk —— Key reconnaissance data sheets or sub- assessment with local knowledge, known sidiary maps developed as part of the landslides, and past events and ask whether risk assessment process the results are realistic and reasonable or whether the method needs refining. Abstract a The MCU should review the list and decide short list of high-risk communities from the how well each of the priority communities GIS for final verification. meets the selection criteria and whether they CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 5 7 are within the scope of the project. Some of the vention against the criteria decided in sec- more technical aspects of this review may tion 4.3.2 (table 4.11). require further discussion with experts on the Finally, the MCU should report, agree, and task team. Other information (or pressures) sign off on the community short list with the from communities and their political repre- government and the project funding agency. sentatives may need to be tested against the results of the risk analysis to justify the final MILESTONE 4: list of prioritized communities. Process for community selection For each of the communities on the priority list, the MCU should provide a short summary agreed upon and communities justifying its suitability for a MoSSaiC inter- selected TAB L E 4.11  Sample justification for community selection JUSTIFICATION FOR DECISION SUITABLE FOR COST- COMMUNITY MoSSaiC EFFECTIVE NOTES Selected for MoSSaiC • A vulnerable community with multiple households exposed to landslide hazards (rotational or translational slides in weathered materials) A Yes Yes • A community-based drainage intervention is potentially appropriate for reducing the hazard • Housing density is high giving a low drain length, and construction cost, per house Selected for MoSSaiC • A vulnerable community exposed to landslide hazards (rotational or translational slides in weathered materials) as a result of surface water runoff Yes, if from roads above the community and from households combined with B Yes • A suitable location for a road drainage intervention that would protect road drainage intervention adjacent houses and the road, combined with a community-wide drainage intervention • Per house cost could potentially be high, but this would be offset by preventing loss of road (a high-cost event) Not selected for MoSSaiC • A moderately wealthy community exposed to multiple small landslide hazards (rotational or translational slides in weathered materials) in cut slopes behind houses C Yes No • Low housing density, so a community-wide drainage intervention would have a high cost per house • A more cost-effective solution would be education and enforcement of regulations relating to cut slopes, drainage, and retaining structures at the household level Not selected for MoSSaiC • Landslide hazard is caused by, and/or only affects, one house (low exposure) • The landslide hazard relates to physical processes not targeted by MoSSaiC D No No approach • An appropriate risk reduction approach would be relocation of the household, or a localized engineering intervention such as a retaining wall; not a community-based or community-wide MoSSaiC drainage intervention 1 5 8    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S 4.7 PREPARING A BASE MAP FOR Topographic, or contour, maps provide a DETAILED COMMUNITY useful starting point for preparing the base MAPPING map, since the scale and coordinate system are known and topographic units can be recog- nized. Many topographic maps also include Once the list of prioritized communities has land-use information and the locations of been confirmed, the mapping task team should houses, roads, paths, and drainage lines—thus compile all the spatial data available to pro- providing a head start in the detailed mapping duce a composite base map for each commu- of a community (figure 4.6b). A base map that nity. These maps will be used to identify the includes these features as vectors (points, precise localized slope processes and trigger- lines, and polygons) is usually quite clear and ing mechanisms that contribute to the land- easy to interpret; such a document is also very slide hazard in each community. This detailed easy to annotate. community mapping is undertaken in the next stage of the project (chapter 5). 4.7.2 Supporting data The base map is used both as a guide in Maps of geology, lithology, and soils can pro- locating and understanding these slope pro- vide useful supplementary data in support of cesses, and as a template to which detailed field observations and slope stability calcula- observations can be added by the community tions. In general, however, they should not be mapping team and the residents. The anno- included in the base map owing to the sheer tated base map is thus a working document in volume of information they would add. Aerial the identification of landslide causes and and satellite photos can similarly supplement potential solutions. It may be used as an input the base map, providing information on the for physically based analysis of slope stability location of houses, paths, and—sometimes— and to communicate slope stability concepts drainage routes; but the density of their infor- and project aims to the community. And, after mation and the solid coloration of these raster many revisions, it will provide the template for images can make annotation difficult (fig- the detailed drainage design and work pack- ure 4.6c). On the other hand, aerial photos are ages for construction. a very useful tool for engaging residents in dis- cussing landslide and drainage issues. 4.7.1 Useful features If field reconnaissance forms have been It is useful to work from a geo-referenced map used in the rapid assessment of landslide haz- of the community. Such a map will make it ard and vulnerability (as described in this easier to analyze the cause/effect relationships chapter), this information should be added to between slope features, processes, and land- the base map or included in the supplemen- slide triggering mechanisms, and will allow tary material. measurements to be made, other maps to be overlaid, and GPS locations to be identified. 4.7.3 Sources of spatial data Base maps should be at the most detailed If field reconnaissance was the main method- resolution possible to permit identification (or, ology for community selection and there are later, addition) of individual features such as no digital maps, photocopy and scale up any houses, paths, and drainage patterns (fig- available hard-copy maps of each community ure 4.6a). The area covered by each base map as necessary. should encompass the topographic unit within Where GIS-based mapping was used in which the community resides (i.e., the hillside the community selection, print out a high- or drainage subcatchment), since this is the resolution base map of each community. Ide- greatest area over which potential landslide ally, the base map should comprise GIS layers mechanisms and associated environmental with vector data (points, lines, and polygons) factors may operate. showing contours, roads, paths, drains, and CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 5 9 F IG U R E 4 . 6  Generating the base map from a topography map and an aerial photo a. A community base map prepared from the original topographic map (b) and updated using an aerial photo (c). b. A topographic map may be available. In this c. An aerial photograph of the community can be example, the main roads and some of the houses used in updating existing digital maps to create in the community are also shown. the base map and as a supplementary resource for the community mapping process. Source: Reproduced with permission of the Chief Surveyor, Ministry of Physical Planning, St. Lucia. houses. Try not to include raster layers, such Depending on the quality of the survey con- as aerial photographs or digital elevation ducted and whether the plans are geo-refer- models, or layers with soils, geology, and enced, such information can be a useful part of lithology; these data can be provided as sup- the base map. However, maps and information plementary maps. consolidated from government or other A final source of information for the base sources may not be up to date. Before these can map may be surveys and plans generated for be added, significant on-site verification and previous community projects, such as the con- further relevant detail may be needed; this struction of paths and other infrastructure. process is outlined in section 5.4. 1 6 0    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S 4.8 RESOURCES 4.8.1 Who does what CHAPTER TEAM RESPONSIBILITY ACTIONS AND HELPFUL HINTS SECTION Agree to the community • Become familiar with potential community selection 4.3.2; 4.6 selection process criteria approaches Funders and Coordinate with the MCU and policy makers government task team Agree to the list of prioritized • Review the report from the community selection team communities Build the community selection • Identify task team members from relevant government 4.2; 4.3 team ministries and other agencies Coordinate with the government • Review available software and existing data on landslide 4.3 task team susceptibility or hazard and community vulnerability Agree on and communicate the • Identify an appropriate assessment method process for community selection • Modify the project step template (section 2.6) MCU • Review the task team report 4.6 Finalize the prioritized list of • Finalize community selection against agreed-on selection communities criteria and report to government and funders and policy makers Coordinate with funders and policy makers • Review available software and existing data on landslide 4.4; 4.5 Agree on and communicate the susceptibility or hazard and community vulnerability process for community selection • Identify an appropriate assessment method • Modify the project step template (section 2.6) Assess landslide susceptibility or • Data acquisition and application of selected methodology 4.4 hazard Assess community exposure and • Data acquisition and application of selected methodology 4.5 Government task vulnerability teams • Combine hazard and vulnerability data to indicate 4.6 Generate a prioritized list of relative risk at-risk communities • Confirm list with site visit and rapid reconnaissance • Write report for the MCU Report to the MCU Prepare the community base • Acquire all relevant spatial data to assist in the mapping 4.7 map within the selected communities CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 61 4.8.2 Chapter checklist SIGN- CHAPTER CHECK THAT: TEAM PERSON OFF SECTION 99Capabilities, personnel, data, and software identified 4.3 99Appropriate method specified for selecting communities 4.3.2 99Areas of landslide hazard identified and ranked 4.4 99Most vulnerable communities identified and ranked 4.5 99Overall landslide risk to communities determined and priority communities 4.6 identified 99Milestone 4: Process for community selection agreed upon and communities 4.3.2; 4.6.2 selected 99Base maps for the short-listed communities prepared 4.7 99All necessary safeguards complied with 1.5.3; 2.3.2 4.8.3 References Dai, F. C., C. F. Lee, and Y. Y. Ngai. 2002. “Landslide Australian Geomechanics Society. 2000. Risk Assessment and Management: An “Landslide Risk Management Concepts and Overview.” Engineering Geology 64: 65–87. Guidelines.” http://australiangeomechanics. Department for International Development. 2006. org/admin/wp-content/uploads/2010/11/ “Frequently Asked Questions on Disaster Risk LRM2000-Concepts.pdf. Reduction.” http://webarchive.nationalarchives. Castellanos Abella, E. A., and C. J. van Westen. gov.uk/+/http://www.dfid.gov.uk/Media-Room/ 2007. “Generation of a Landslide Risk Index News-Stories/2006-to-do/Frequently-Asked- Map for Cuba Using Spatial Multi-Criteria Questions-on-Disaster-Risk-Reduction-/. Evaluation.” Landslides 4: 311–25. Finlay, P. J., G. R. Mostyn, and R. Fell. 1999. —. 2008. “Qualitative Landslide Susceptibility “Landslide Risk Assessment: Prediction of Assessment by Multicriteria Analysis: A Case Travel Distance.” Canadian Geotechnical Journal Study from San Antonio del Sur, Guantánamo, 36 (3): 556–62. Cuba.” Geomorphology 94 (3–4): 453–66. Harp, E. L., M. E. Reid, J. P. McKenna, and J. A. Cheng, P. F. K. 2009. “The New Priority Ranking Michael. 2009. “Mapping of Hazard from System for Man-Made Slopes and Retaining Rainfall-Triggered Landslides in Developing Walls.” Special Project Report SPR4/2009, Countries: Examples from Honduras and Geotechnical Engineering Office, Government Micronesia.” Engineering Geology 104 (3–4): of Hong Kong Special Administrative Region. 295–311. http://hkss.cedd.gov.hk/hkss/eng/download/ SIS/cnprs/SPR%204_2009.pdf. Ko Ko, C., P. Flentje, and F. Chowdhury. 2004. “Landslides Qualitative Hazard and Risk Crozier, M., and T. Glade. 2005. “Landslide Hazard Assessment Method and Its Reliability.” Bulletin and Risk: Issues, Concepts and Approach.” In of Engineering Geology and the Environment 63: Landslide Hazard and Risk, ed. T. Glade, M. G. 149–65. DOI 10.1007/s10064-004-0231-z http:// Anderson, and M. Crozier, 1–40. Chichester, www.springerlink.com/content/ UK: Wiley. eqa4jf2jq95p7mfa/fulltext.pdf. Cruden, D. M., and D. J. Varnes. 1996. “Landslide Types and Processes.” In Landslides: Liang, R. Y., 2007. “Landslide Hazard Rating Investigation and Mitigation, Transportation Matrix and Database.” Final report, FHWA/ Research Board Special Report 247, ed. A. K. OH-2007/18, U.S. Federal Highways Turner and R. L. Shuster, 36–75. Washington, Administration and Ohio Department of DC: National Academies Press. Transportation. 1 62    C H A P T E R 4 .   S E L E C T I N G CO M M U N I T I E S Montgomery, D. R., and W. E. Dietrich. 1994. “A van Westen, C. J., E. A. Abella, and L. K. Sekhar. Physically-Based Model for the Topographic 2008. “Spatial Data for Landslide Susceptibility, Control on Shallow Landsliding.” Water Hazards and Vulnerability Assessment: An Resources Research 30: 1153–71. Overview.” Engineering Geology 102 (3–4): 112–31. Pack, R. T., D. G. Tarboton, and C. N. Goodwin. 1998. “The SINMAP Approach to Terrain Wong, H. N., and K. K. S. Ho. 1996. “Travel Stability Mapping.” Paper submitted to 8th Distance of Landslide Debris.” In Landslides, Congress of the International Association of vol. 1, ed. K. Sennest, 417–22. Rotterdam: Engineering Geology, Vancouver, September Balkema. 21–25. http://hydrology.usu.edu/sinmap/. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 63 “Community participation has been recognized as the additional element in disaster management necessary to reverse the worldwide trend of exponential increase in disaster occurrence of and loss from small- and medium-scale disasters.” —Lorna P. Victoria, Director, Center for Disaster Preparedness, Philippines (2009, 1) CHAPTER 5 Community-Based Mapping for Landslide Hazard Assessment 5.1 KEY CHAPTER ELEMENTS 5.1.1 Coverage This chapter illustrates how to work with MoSSaiC (Management of Slope Stability in communities to develop a map of slope drain- Communities) process. The listed groups age and landslide hazard for use in the should read the indicated chapter sections. AUDIENCE CHAPTER F M G C LEARNING SECTION     The community mapping process 5.4   How to assess if a MoSSaiC intervention is suitable 5.5, 5.6    How to develop an initial drainage plan for landslide hazard reduction 5.7 F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors 5.1.2 Documents CHAPTER DOCUMENT TO BE PRODUCED SECTION Community slope feature map 5.4 Slope process zone map 5.5 Initial drainage plan 5.7 Priority matrix of slope zones and proposed drainage interventions 5.7 165 5.1.3 Steps and outputs STEP OUTPUT 1. Identify the best form of community participation and mobilization MCU agrees on • Review and determine the most suitable form of community participation appropriate • Identify available community liaison experts in government community participation strategy 2. Include key community members in the project team Key community • Identify existing or new community representatives members included • Hold initial discussions with community representatives to brief them on mapping and project rationale 3. Plan and hold a community meeting First community • Take advice from government and community representatives on location and meeting held style of meeting • Compile a community base map from existing maps, plans, and aerial photos (see section 4.7) to bring to the meeting 4. Conduct the community-based mapping exercise; this will entail a considerable Community slope amount of time in the community feature map • Talk with residents in each house to begin the process of engagement, knowledge sharing, and project ownership • Observe and discuss wide-scale and localized slope features and landslide hazard • Add local knowledge and slope feature information to the base map 5. Qualitatively assess the landslide hazard and potential causes Slope process • Use the community slope feature map to identify zones with different slope zone map (relative processes and landslide hazard landslide hazard) • Evaluate the role of surface water infiltration in contributing to the landslide hazard 6. Quantitatively assess the landslide hazard and the effectiveness of surface Determination of water management to reduce the hazard viability of • Use physically based software or simpler means to assess the likely contribu- MoSSaiC approach tion of surface water to landslide hazard • Assess whether reducing surface water is likely to reduce landslide hazard 7. Identify possible locations for drains Initial drainage plan • For each slope process zone, determine the most appropriate surface water and prioritization management approach matrix • Prioritize the zones according to relative landslide hazard 8. Sign off on the initial drainage plan: organize a combined MCU-community Initial drainage plan walk-through and meeting to agree on the initial drainage plan sign-off This chapter provides guidelines for involving with sign-off on the initial drainage plan. The and engaging the community; a step-by-step final drainage plan for landslide hazard reduc- description of how to develop a community tion is designed in chapter 6. slope feature map; principles for identifying slope process zones and assessing landslide 5.1.4 Community-based aspects hazard; and examples of quantitative, physi- The chapter outlines different processes for cally based methods for confirming landslide community participation and how to work hazard and slope drainage processes. Mile- with community members to produce a map stone 5 is achieved at the end of this chapter of slope drainage and landslide hazard. 1 6 6    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T 5.2 GETTING STARTED ment of landslide hazard reduction measures. The initial community slope feature map is 5.2.1 Briefing note eventually developed into a formal drainage plan (chapter 6) detailing drain alignments, What is community-based mapping for household connections, and other related landslide hazard assessment? works for reducing landslide hazard. Community-based mapping is a central ele- In contrast, traditional community-based ment of MoSSaiC. It allows identification of (participatory) landslide hazard mapping the natural and human causes of slope insta- approaches are typically used to provide infor- bility at a sufficiently detailed scale for poten- mation to residents and authorities so that tial landslide hazard reduction measures to be construction can be limited in hazardous loca- determined. tions, disaster preparedness improved, and The starting point is the mapping of detailed vulnerability reduced. These landslide hazard slope features (at scales of 10–50 m) and stabil- maps are usually seen as an output from the ity history based on community residents’ exercise rather than an input for designing knowledge and careful observations by engi- hazard reduction measures. neers or landslide experts. By mapping slope Similarly, wide-scale (regional or country- features at this scale, zones of different slope based) landslide hazard maps usually deliver stability processes and relative landslide haz- information that provides only general guid- ard can be identified. An initial assessment is ance as to areas of landslide susceptibility or then made of the role of surface water infiltra- hazard. Such maps do have a role to play in tion in contributing to the landslide hazard, MoSSaiC, and chapter 4 reviews how they can allowing the potential effectiveness of surface be generated and used in selecting communi- water drainage in reducing the landslide haz- ties where MoSSaiC projects might be rele- ard to be evaluated. Scientific methods are vant. However, the information contained in used to confirm and refine the landslide haz- these maps is not resolved at a sufficiently fine ard assessment. Finally, possible locations of scale to capture the detailed physical causes or new surface drains are discussed with the triggers of potential landslides (as described in community, and an authorized stakeholder chapter 3). They thus cannot provide enough signs off on the prioritized zones and initial information to design physical landslide haz- drainage plan. ard mitigation measures in communities. Community-based landslide hazard map- Landslide processes at the community scale ping is a two-way learning process. Engaging with individuals in the community enables the Understanding the mechanisms that trigger synthesis of their detailed local knowledge of landslides, and the scale at which they operate, the slope with scientific and engineering provides the scientific basis for mitigating knowledge of slope processes. During these landslide hazard. As outlined in chapter 3, discussions, community awareness of slope landslide hazard results from a combination of processes and of good and bad slope manage- preparatory factors relating to slope geometry, ment practices is also likely to be raised. soil and geology, vegetation, surface water and groundwater regimes; and triggering mecha- Why is such a detailed map necessary? nisms such as rainfall and seismic events. Mapping landslide hazard at the community Tropical regions are especially susceptible to level is a vital component of the overall land- landslides because of high-intensity and high- slide hazard reduction process described in duration rainfall events, the rapid rate of section 1.2. weathering, and resulting deep soils (often on Community-based mapping is very much steep slopes). Rainfall is the main landslide the start of the MoSSaiC process in a particu- trigger in the tropics, and preliminary evi- lar community, and an input to the develop- dence suggests that climate change could pro- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 6 7 duce more intense precipitation events in • identify zones of past, present, and poten- regions such as the Caribbean, thus increasing tial future landslide hazard; the probability of landslides (Knutson et al. • provide information about the local topog- 2010). raphy (~30 m scale) and mechanisms con- Even without climate change, anthropo- tributing to slope instability such as drain- genic activities are increasing landslide risk in age and poor construction practices (~10 m some of the most vulnerable communities. scale); These activities include altering slope geome- try with earthworks (cut and fill), changing • contain sufficient information to allow a slope vegetation, loading slopes with buildings scientific assessment of landslide hazard and infrastructure; all of which can cause vari- (using data such as slope angle, basic soil ations in surface water and groundwater characteristics, vegetation cover, and regimes. The pressure of development on both sources of household water as inputs to land and population results in the poorer, most slope stability models); vulnerable sections of society living on the • be sufficiently accurate to allow the provi- most-marginal, landslide-prone hillsides. sional alignment of new drains to be plotted; The scales at which the preparatory and anthropogenic factors operate were summa- • be comprehensive, incorporating informa- rized in chapter 3 (table 3.6). At the hillside tion from residents and measurements scale (100–1,000 m), geographic information made on the ground; and system– (GIS-) based mapping techniques can be used to identify zones of increased • be clear, so that residents, engineers, and landslide hazard or susceptibility by overlay- decision makers can understand and cor- ing and indexing topographic, soil/geology, rectly interpret it. and vegetation maps. But to predict landslide To meet these criteria, community-based hazard so as to inform a community-based mapping and landslide hazard assessment landslide risk reduction strategy requires that must be carried out carefully and rigorously. certain parameters be resolved at the house- hold scale (1–10 m). In densely populated 5.2.2 Guiding principles communities, it is vital to identify the effects The following guiding principles apply in of highly localized surface water regimes, community-based mapping and landslide haz- manmade structures, and cut slopes. The sur- ard assessment: face- and groundwater regimes in such loca- tions will vary over short time scales in • Recognize the importance of full and response to rainfall events and the addition of repeated consultation and discussion with household water to the slope. These physical community residents; recognize the value parameters need to be modeled in a fully of their knowledge of slope features and dynamic way (i.e., over time) to reveal the processes, and be aware of different con- precise mechanisms determining the stability cerns, perceptions of risk, and competing of the slope, and hence how slope stability agendas. can be improved. • Ensure that the wider topographic controls What information should be on the map? on drainage, soil depth, and slope stability are identified; be aware of potential con- Detailed community-based mapping of slope nections between features in one part of the features provides information for determining slope and the related landslide hazard in the local slope destabilizing mechanisms and another. the potential for rainfall-triggered landslides. A well-constructed community slope feature • When considering small-scale instability map will affecting individual houses, be alert to 1 6 8    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T potential pressure from owners to solve Engage the community in the science of their specific problems; do not neglect look- landslide risk reduction from the very begin- ing for wider causes and solutions. ning of the project, using illustrations to help explain slope processes and good slope man- • Construct maps carefully and clearly to agement practices. This builds trust and ensure all relevant information is captured encourages those within the community to bid and available for future reference. Each on the possible works. mapping stage builds on the information The slope feature map should be the prod- from the previous map to develop an accu- uct of several visits to the community, not just rate drainage plan and work packages for a single two- to three-day mission. Repeated construction. visits test initial thoughts, encourage the maxi- • Undertake repeated community walk- mum number of community residents to par- throughs to ensure adherence to all of the ticipate, and provide the best opportunity for above principles. securing information critical to the formula- tion of landslide mitigation measures. • Ensure that all relevant safeguards are addressed. Learning by doing The community-based mapping process is an 5.2.3 Risks and challenges integral part of community and government Mapping topographic features at the necessary training in good practice for landslide risk resolution reduction. The government task teams will need to be open to what they can learn from Identifying major topographic features is a community residents and from one another. critical element of the walk-through and field Team members with technical or engineering survey processes. It is likely that the existing backgrounds will have to adapt their typical plans and maps incorporated in the commu- data acquisition and mapping approaches to nity base map (as described in section 4.7) will incorporate community knowledge. Project not be resolved at sufficient detail to reliably managers and supervisors of construction indicate zones of water convergence or diver- works might need to identify new ways to gence on the slope. Identification of topo- involve community residents and contractors. graphic hollows at a scale of ~30 m is integral Conversely, team members with roles in com- to the MoSSaiC mapping process, and time munity development will need to familiarize must be spent in carefully identifying such fea- themselves with some of the more technical tures, since they are likely to control soil water aspects of the mapping process. flow and pore pressure changes, and thus Connecting with key community members landslide hazard. Spending time in the community throughout Spending sufficient time with the community the process encourages key members of the Community members can provide a signifi- community to own the project—and, more cant amount of information regarding the importantly, to own the methodology. Their drainage conditions that prevail on the slope engagement thus becomes a significant train- during heavy rain. Repeated efforts should be ing opportunity, in that they may thus become made to talk to as many residents as possible. advocates for MoSSaiC and potential trainers Choose times when the majority of residents themselves. Identify respected residents in the are at home, such as early evenings, weekends, community to champion MoSSaiC. and public holidays. Try to visit the commu- Challenges of community engagement nity during heavy rainfall to observe drainage patterns and issues, and to discuss these with Communities should not be seen as idealized residents. entities with homogenous views, abilities, or CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 69 vulnerabilities. Recognize that some residents This section introduces some general com- may have diverging agendas. munity participation principles and identifies Residents’ attitudes toward participating in specific principles and practices related to a community-based hazard mapping exercise MoSSaiC. Comprehensive guidelines on com- are likely to be influenced by their perception munity participation for development and of risk (chapter  8). In communities where disaster risk reduction are often available from landslides have occurred, residents may some- international development agencies and prac- times be less receptive to mitigation measures titioners such as nongovernmental organiza- than the general public since they are likely to tions (NGOs). have a sense of powerlessness (Lin et al. 2008). Although residents may correctly identify 5.3.1 Community participation: slope surface processes and features, their Principles interpretation of the importance of these in An important MoSSaiC project objective is to determining slope stability may be incomplete. achieve behavioral change among all stake- Local knowledge thus must be integrated with holders regarding landslide risk reduction in scientific and expert knowledge. communities. To this end, community resi- dents should be enabled to participate in the 5.2.4 Adapting the chapter blueprint to complete process of mapping, drainage existing capacity design, contracting, construction, and main- Use the matrix opposite to assess the quality of tenance; and government task teams should core mapping data (the base map) for each be prepared to spend significant time on site community, and government capacity to com- with the community. MoSSaiC project steps bine scientific and community-based knowl- and expenditure profiles should demonstrate edge of local landslide processes. This informa- government commitment to a high level of tion will guide the process of community-based community engagement. Previous experi- mapping for landslide hazard assessment. ence shows that the majority of total project expenditure can be within the community in 1. Assign a capacity score from 1 to 3 (low to the form of construction materials and labor high) to reflect existing capacity for each costs. element in the matrix’s left-hand column. Determine the most appropriate form of 2. Identify the most common capacity score as participation an indicator of the overall capacity level. Approaches to community participation can 3. Adapt the blueprint in this chapter in accor- be defined as instrumental, collaborative, or dance with the overall capacity level (see supportive. The Active Learning Network for guide at the bottom of the opposite page). Accountability and Performance in Humani- tarian Action describes these approaches as follows (ALNAP 2003): 5.3 DECIDING ON HOW TO • Instrumental approaches regard commu- WORK WITHIN A nity participation as a means of achieving COMMUNITY project objectives; while these approaches can build community capacity, this is not a Before community engagement is instigated, project objective in itself. the MoSSaiC core unit (MCU) and the govern- ment task teams should understand different • Collaborative approaches are based on forms of community participation and the exchange of resources throughout the proj- community-based foundation for MoSSaiC ect cycle in order to achieve a shared objec- projects (section 1.4.3). tive. With this type of approach, the govern- 1 70    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T EXISTING CAPACITY CAPACITY ELEMENT 1 = LOW 2 = MODERATE 3 = HIGH MoSSaiC core unit (MCU) and No existing plans or maps of Some plans or maps available, Geo-referenced digital plans government resources for the selected communities but with incomplete or or maps available with all developing community base low-resolution data necessary information maps at the household scale (contours, house locations, paths, roads, drainage lines) Government capacity for • Limited government activity Significant number of Established community- engagement with communi- in community development community-based projects government liaison and track ties in development or or disaster risk management undertaken, but no formal record of successful projects disaster risk management • No government agency with agency has overall mandate for working in/with responsibility communities Capacity and structure of No formal community Community-elected represen- Active community-based communities structure or community- tatives or community-based organizations with elected based organizations organizations, but generally members and good accep- inactive or with limited tance within community and influence by government MCU and government task No experience in direct Some experience in direct Prior experience in direct team experience in landslide mapping or assessment of mapping of slope processes mapping of slope processes hazard assessment and surface slope processes related to but limited or no experience and the use of scientific water management landslide hazard in landslide hazard assessment methods/models for assessing landslide hazard Project safeguards Documented safeguards need Documents exist for some Documented safeguards to be located; no previous safeguards available from all relevant experience in interpreting and agencies operating safeguard policies CAPACITY LEVEL HOW TO ADAPT THE BLUEPRINT 1: Use this chapter The MoSSaiC core unit (MCU) needs to strengthen its resources prior to starting the community-based in depth and as a mapping and landslide hazard assessment process. This might involve the following: catalyst to secure • Holding discussions with the community liaison task team to identify any previous community project in support from the area that may help in establishing a dialogue with the community other agencies as appropriate • Talking with the community to see if there is a natural community spokesperson who could be a focus for engagement, but taking note of the risks and challenges in community engagement mentioned above • Talking with commercial or academic partners to ascertain their willingness to share in or collaborate on slope stability analysis • Approaching all relevant agencies to acquire their safeguard documents and distill them into a coherent working document for community engagement 2: Some elements The MCU has identified strength in some areas, but not all. Elements that are perceived to be Level 1 need of this chapter to be addressed as above. Elements that are Level 2 will need to be strengthened, such as the following: will reflect current • If there is limited expertise in map/plan production, advice could be sought from a commercial or practice; read the academic partner or relevant agency remaining elements in depth • If relevant safeguard documents are available but not collated, the MCU should systematically integrate and use them to them further strengthen • If there is limited expertise in community engagement, seek advice from nongovernmental organizations capacity or other agencies with experience in this area 3: Use this chapter The MCU is likely to be able to proceed using existing proven capacity. It would nonetheless be good as a checklist practice for it to document relevant experience in community-based projects and related safeguards. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 7 1 ment or agency aims to build the capacity of • community knowledge and expert knowl- the community and also to learn from it. edge, There is no expectation of existing commu- • project scope and community perceptions nity structures (formal leadership or com- of risk, and munity-based organizations), and collabo- ration for specific tasks may be through • policy constraints and community decision- informal delegation or development of for- making powers. mal partnerships. Consider culture and social organization • Supportive approaches recognize existing The United Nations notes that “Disaster risk or potential capacity within a community— reduction projects, policies and programs will the government or agency provides techni- be meaningful and successful only if the inter- cal, financial or material support for the ests of the whole community are taken into community to initiate and undertake its consideration” (UN 2008, v). Different cul- own project. tures and communities will have different MoSSaiC is most closely aligned with the experiences and expectations of participation collaborative approach, but the MCU and in community-based projects. Consider the community liaison task team should also seek potential effect on participation of local beliefs, and support existing community capacity language, and history; and aspects of social where possible. organization such as ethnic composition, gen- Putting a particular participatory approach der relations, relationships between different into practice involves a series of activities. The generations, and social hierarchies. ladder of participation (table  5.1), originally Also consider the participation of less- developed by Arnstein (1969), is a helpful way prominent or vocal groups (which may include of describing the type of participation and the women, the elderly, children and youth, peo- role of community residents in project activi- ple with disabilities, and the poorest resi- ties. dents), and varying levels of participation The MCU and the community liaison task within the community due to different levels team should decide on a participation strategy of interest or knowledge. that allows an appropriate (and realistic) bal- Ensure that the participation strategy is ance between culturally and socially appropriate, and that TA BLE 5 .1  Types of community participation TYPE OF PARTICIPATION COMMUNITY ROLE Local initiatives Conceives, initiates, and runs project independently; agency participates in the community’s projects Interactive Participates in the analysis of needs and in program conception, and has decision-making powers Through the supply of Supplies materials and/or labor needed to operationalize an intervention materials, cash, or labor or cofinances it; helps decide how these inputs are used Through material incentives Receives cash or in-kind payment from agency By consultation Asked for views on a given subject, but has no decision-making powers Through the supply of Provides information to agency in response to questions, but has no information influence over the process Passive Informed of what is going to happen Manipulative Participation is simply a pretense Sources: Pretty 1995; World Bank 2010. 1 7 2    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T less-prominent groups are empowered and strategy a sensitive and positive policy of inclu- included in the project. sion and empowerment for all residents, including women. Such inclusion should go Consider gender relations beyond a “token” approach that, for example, Genuine inclusion of gender considerations is simply mandates a certain number of women likely to result in more sustainable projects serve on a particular committee. (UNISDR 2008). More broadly, equality is Table 5.2 provides a practical gender-sensi- widely regarded as essential in reaching the tive risk assessment checklist (UN 2009), ultimate goal of development—the well-being much of which is relevant to MoSSaiC’s com- of all people (Klasen 1999). In this regard, it is munity-based approach to landslide hazard useful to understand and apply a strategy of gender mainstreaming. The United Nations Economic and Social Council defines gender F IGUR E 5.1  Access and control over resources in Ethiopia by mainstreaming as women and men …the process of assessing the implications for a. Women women and men of any planned action, including legislation, policies or programmes, credit in all areas and at all levels. It is a strategy for meetings access making women’s as well as men’s concerns information sources control and experiences an integral dimension of the boys design, implementation, monitoring and girls evaluation of policies and programmes in all adult men political, economic and societal spheres so adult women that women and men benefit equally and storage tank inequality is not perpetuated. The ultimate roof goal is to achieve gender equality donkey/ox cart (UNECOSOC 1997). bicycle water containers Women have a critical role to play in all tap stand aspects of community-based projects. Women 0 1 2 3 4 5 6 7 8 9 10 bring different skills and expertise to the table, score as a participant in a Pacific community case a. Men study observed: credit Women are great at implementing and organ- meetings ising and they advise the chiefs. The women information sources are the very strong part of the village because boys they take care of their families. They make girls sure the kids are safe and the water is clean adult men (Gero, Meheux, and Dominey-Howes 2010, adult women 36). storage tank roof Frequently, however, men dominate, given donkey/ox cart their control of nearly all resources available at bicycle the household level (University of Warwick water containers 2002) (figure 5.1). tap stand Experience has shown that gender main- 0 1 2 3 4 5 6 7 8 9 10 streaming is often difficult to realize (UN score 2002) and cannot be achieved without explicit Source: University of Warwick 2002. commitment to the strategy and systematic Note: A maximum of 10 points was allocated between women and men to efforts to implement it. represent their relative access to, and control over, each resource listed. A score of 10 indicates that that sex has sole access to/control over a particular resource; The MCU and community liaison task team a score of 5:5 would indicate that women and men enjoy equal access/control. should incorporate into the participation CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 73 reduction. Consider adapting this list and nity walk-throughs, and construction of prior- incorporate it into the community-based map- ity ranking matrixes. ping and landslide hazard assessment pro- This subsection describes some of the prac- cesses in this chapter. tices for initiating and sustaining community engagement in MoSSaiC projects. Section 5.3.3 5.3.2 Community participation: Practices describes specific points of engagement dur- Typical practices for community participation ing the community-based mapping process. in project initiation and design may include The MCU and community liaison task team informal and formal communication such as should use this guidance to translate their meetings, focus groups, and interviews; and principles and strategies for community par- practical activities such as mapping, commu- ticipation into practice. All government task TAB L E 5.2  Checklist for gender-sensitive risk assessment STEP GENDER-SENSITIVE ACTION 1. Identifying • Identify and implement strategies that are socially and culturally sensitive to the context to actively engage risks women and men from the communities in local risk identification • Map the available community organizations that can ensure the participation of both men and women, and involve them in consultation on hazards, including collecting and sharing information and assessing risk • Determine the risks faced by men and women separately in each region or community • Include women’s traditional knowledge and perception in the analysis and evaluation of the characteristics of key risks • Involve women and men equally in the process to review and update risk data each year, and include information on any new or emerging risks 2. Determining • Ensure the active engagement of men and women in vulnerability analysis (by engaging men’s and women’s vulnerabilities organizations and setting schedules that enable the participation of both men and women) • Conduct gender analysis for the identification of gender-based inequalities between men and women • Map and document the gender-differentiated vulnerabilities (physical, social, economic, cultural, political, and environmental) • Ensure the inclusion of gender-based aspects of age, disability, access to information, mobility, and access to income and other resources that are key determinants of vulnerability identification • Identify and include women’s needs, concerns, and knowledge in the community vulnerability assessments conducted for all relevant natural hazards 3. Identifying • Acknowledge and assess women’s and men’s traditional knowledge capacities • Ensure the capacities of all women’s groups, organizations, or institutions are assessed along with those of men • Identify the specific functions, roles, and responsibilities carried out by women and men and build these into the analysis • Identify the gender-specific support mechanisms for women to get involved in risk management programs and actions (e.g., mobility and child care issues) • Identify mechanisms to enhance the existing capacities of both men and women, and ensure that capacity- building programs incorporate measures to enable women’s participation • Recognize the equal importance of the capacities and authority of women and men empowered to conduct risk assessment programs or train other members of the community • Actively engage women’s organizations to assist with capacity building • Identify female role models to advocate for gender-sensitive risk assessment 4. Determine • Involve both women and men in the development of hazard and risk maps acceptable • Collect and analyze gender-differentiated data for assessing acceptable levels of risk levels of risk • Ensure that hazard maps include the gender-differentiated impacts of risk • Ensure that hazard maps include gender-differentiated vulnerability and capacity Source: UN 2009. 1 74    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T teams should be briefed on the participation localized controls that exist with respect to principles and practices before engaging with landslide hazard. the community. Involve community leaders Sensitize communities and government task Identify those residents with leadership roles teams in the community; this may require repeat The MoSSaiC community-based mapping visits to the community. While some leaders process starts with discussions between two are elected and thus immediately known, lead government task teams (the community others may have leadership roles that ema- liaison task team and the landslide assessment nate solely from informal social networks and engineering task team) and community within the community, which can take time residents. The government teams need to lis- to understand. Community engagement has ten to and understand residents’ concerns very specific challenges. In some locations, regarding landslides, and learn what residents communities may be relatively well orga- consider the main causes of the landslide risk nized with elected persons representing the (figure  5.2). They should allow residents to community’s interests to local social inter- freely discuss issues related to maintenance of vention funds, government agencies, and drains and the practice of discharging both NGOs. Even with relatively clear structures, rain and gray water onto slopes. In this way, though, leadership roles—and those who fill they become sensitized to the specific charac- those roles—can change as projects move teristics of the community as well as to the from concept to implementation and deliv- landslide hazard. ery. Understand community risk perception and agendas FI G U R E 5.2  Listening to community residents is important Community representatives can greatly assist in providing information on slope features relating to landslide hazard. However, it can be a challenge to ensure that the advice received from such representatives is truly objective—particularly since landslide haz- ard reduction measures (such as drains), aimed at protecting the community as a whole, can seem to benefit certain individual properties more than others. Community information should be assessed and moder- ated through a number of mechanisms prior to any final decisions on drainage interven- Conversely, the mapping process allows the tions being made. government task teams to raise community To ensure that the interests of all groups awareness about the potential causes of land- within the community are heard and that slides and therefore what the possible solu- information is triangulated, use a variety of tions might be. This process should be under- participatory activities such as the following: taken in such a way that the resulting • Informal discussions with community resi- community slope feature map can be used to dents while mapping, stopping for lunch identify zones of relatively high landslide haz- breaks, or walking through the community ard and indicate major surface drainage lines in wet season conditions. Community resi- • Formal discussions by the whole commu- dents are thereby sensitized to the highly nity at community meetings CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 75 • Focus groups with separate constituencies (gender, age, ethnic group) or mixed con- F IGUR E 5. 3  Engaging community representatives and guides in identifying stituencies slope features and landslide issues • Discussions with the community’s govern- ment representatives (and other politicians) Engage the community in understanding landslide hazard reduction Maintaining community engagement through- out the project develops trust and is critical for developing residents’ understanding of land- slide hazard causes and solutions. Ensure the mapping process is interactive and takes place over a number of visits to present residents with on-site access to the government task teams and the opportunity leaders of community-based organizations to understand—and contribute to—the fol- whom they would recommend as a guide. Also, lowing: seek out community members who have had experience working alongside government • Assessment of different zones of slope pro- ministries or agencies on other projects. Such cesses and landslide hazard individuals can be a critical link in facilitating • Identification of different types of drainage rapid project acceptance and delivery. intervention in different landslide hazard Visit each house zones With the assistance of the community repre- • Installation of roof guttering and connec- sentatives or guides, the next step is to have tion of wastewater pipes from houses to house-by-house discussions with as many res- drains idents as possible. The community base map 5.3.3 Community knowledge and (prepared in section 4.7) and any additional participation in the mapping process maps or aerial photos should be used to allow residents to add their knowledge of slope fea- Identify community members to guide the tures and slope history. Aerial photos in par- initial community walk-through ticular are a useful focal point. The full techni- Gaining acceptance within communities is a cal details of the mapping process are very important process. At an early stage in presented in section 5.4. community engagement identify one or two House-by-house visits are a crucial part of respected members of the community who are the MoSSaiC mapping process for several rea- willing to accompany the government task sons: teams during community mapping and act as • Conversations allow residents to convey guides (figure 5.3). Ask the guides to start by their priorities—explaining in their own showing the task team the layout of the com- words and in their own way the risks that munity and hillside, and point out any known they face from landslides. areas of landslides and drainage issues. Select people who have lived in the com- • The science of the problem can be explained munity for a while, who are familiar with its and discussed with residents (figure 5.4), layout and history, and who are respected and with direct reference to visible slope fea- trusted by other community members. A good tures (as opposed to a meeting held at a starting point is to ask community leaders or remote venue). 1 76    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T The government task teams thus should FI G U R E 5.4  Discussing slope stability and spend a considerable amount of time in the drainage hazards around residents’ houses community talking to residents. This part of the process may take at least two to three weeks and involve visits on weekends and eve- nings. Create informal focus groups Informal group discussions should be held in tandem with house-by-house visits (fig- ure  5.5), perhaps with a group of residents who have expressed particular interest in the project or with community members who would otherwise be marginalized or less vocal at formal community meetings. • Conversations build trust and allow the project to be fully explained and appreci- ated. F IGUR E 5. 5  Informal group discussion held at an accessible location • Residents have the opportunity to express their desire to be involved in the project (or not) without community peer pressure dynamics that vulnerable groups could find inhibiting at a community or more formal meeting. • Time taken with conversations allows con- tact details such as cell phone numbers to be exchanged when offered. Such informa- tion is valuable, as it allows follow-up for project management and accountability through a two-way flow of information. For focus group meetings, assemble a selec- • Informal conversations reveal the workings tion of base maps and aerial photographs of of the community and provide an important the community. These materials will enable context for the MCU to consider with residents to identify their houses and to mark regard to how it undertakes the bid process relevant surface water issues or indicate any and project implementation. areas of instability they can recall. A poster explaining the science of surface water man- • Conversations provide a means of sensitiz- agement for landslide hazard reduction can ing residents to good practices regarding aid in this discussion. drainage, regardless of whether the partic- ular interventions ultimately form part of Hold formal meetings in or near the community the project. Community meetings should take place at sev- eral stages in the project (figure 5.6). These • These interactions yield information on the may be timed best time to hold community meetings. • before the mapping process begins—to raise • Being invited into residents’ homes allows awareness of the project and what to expect; team members to learn more about the real context of risk as it is perceived and experi- • after the initial period of conversations enced in the home. with residents—once a preliminary version CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 7 7 • a question and answer session. F IG U R E 5 . 6  Local community hall used as venue for hearing residents’ views During these meetings, be clear about the project process, what can and cannot be achieved, and provide any known timelines. Such information, and its accuracy, is critical, as it establishes appropriate expectations for project delivery. Often, the community will have had experience with past projects that failed in this aspect, with promises of delivery that were not met. MoSSaiC programs must set accurate expectations, given the level of community engagement that is sought. of the community slope feature map has 5.4 COMMUNITY SLOPE FEATURE been developed (using the method MAPPING described in section 5.4); • after the qualitative landslide hazard This section describes the technical aspects of assessment, based on the interpretation of the community mapping process—what ques- the slope process zones (section 5.5); and tions to ask residents and the slope features to look for and record. Begin by identifying hill- • after the quantitative landslide hazard side scale slope processes, then walk from assessment, to discuss and agree on an ini- house to house to understand and map local- tial drainage plan to reduce the landslide ized slope stability controls. Researching and hazard (sections 5.6 and 5.7). understanding slope processes at the house- Community meetings provide an opportu- hold scale is a central element in landslide nity for everyone to express their views, for hazard mapping and assessment. information to be shared, and for community Use the items in the following checklist to dynamics to be appreciated more comprehen- capture, and later augment, key slope features sively. Elected representatives, community rep- and the relative location of housing structures. resentatives, the MCU, the government task • Essential items teams, and the media should all attend. Con- —— Base map (from section 4.7) sider advertising meetings through a variety of —— Marker pens and pencils approaches, including informal communica- —— Camera tion within the community (generally the most —— Magnetic compass effective in vulnerable communities) and flyers. —— Surveyor’s measuring tape The initial community meeting should • Additional items if available include —— Abney level • an appropriate welcome; —— Global positioning system (GPS) receiver —— Aerial photo of community • a brief introduction to the project by the MCU or government task team leader out- 5.4.1 Hillside scale: Mapping overall lining the scope of the project (i.e., landslide topography and drainage hazard reduction), the process, and the The first stage of the mapping process is to expected timeline for implementation; determine the hillside scale controls on slope • an opportunity to listen to community rep- stability. With the assistance of a community resentatives’ and residents’ views; and representative, the mapping team should walk 1 78    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T through the community to become familiar with the overall topography, main patterns of F IGUR E 5.7  Community base map and supplementary aerial photograph water movement, and any variations in slope angle and material. Mark these features on the base map (generated in section 4.7; see fig- ure 5.7a) and add, confirm, or correct the posi- tions of houses, paths, drainage lines, and other key structures. Use a compass to take bearings or a GPS receiver to record coordinates; if available, use an aerial photograph (figure 5.7b) to help with navigation and mapping. Topography and natural drainage Topography affects drainage, soil formation, and slope stability over scales as localized as a. A typical community base map compiled from existing contour data 20–50 m. It can be difficult to recognize topo- and building footprints extracted from a recent aerial photo. Contours graphic features at this scale for several rea- may be interpolated and are best used as a general guide to topographic sons: variations (convergent/divergent zones and drainage patterns). See figure 5.18 for an example of this map with slope process features added. • Vegetation can mask the view over even very short distances. • Unauthorized housing can give a false impression of the topography. • Contours on topographic maps may be interpolated from coarser resolution sur- veys, thus smoothing out these features (note the relatively straight and evenly spaced contours depicted in figure 5.7a). The topography of a slope should be described in terms of its constituent convex, b. An aerial photograph of the community can help with identifying concave, or planar (straight) elements, in plan structures and other landmarks. and section (figure 5.8) at a scale of ~20–50 m. Source: Reproduced with permission of the Chief Surveyor, Ministry of Physical In particular, the mapping team should be Planning, St. Lucia. careful to identify concave topographic ele- ments and associated slope processes. • Concave downslope profile (concave in A downslope increase in soil depth can have section). Soil depth is often related to a broadly counterintuitive effect: steeper topography. Where the slope profile is con- slopes, higher up the hillside, can exhibit cave in section (types 7, 8, and 9 in fig- stability because of their shallower soils or ure  5.8), it is common for soil depth to exposed rock (figure 5.10a), while relatively increase downslope (figure 5.9). This is due shallow slopes further downslope may, in to the erosion or mass wasting of soils from certain circumstances, prove less stable due upper slope sections and the deposition of to the accumulation of deeper soils (fig- this material on lower slopes. The depth ure 5.10b). and relative lack of strength of accumulated soils (colluvium) makes them particularly • Topographic convergence zones (concave prone to landslides (section 3.5.3). in plan). Areas of the hillside that are con- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 79 F IG U R E 5 . 8  Topographic elements to be F IGUR E 5.10  Soil depth and stability distinguished and identified in the field profile form rectilinear convex concave straight 1 4 7 plan form convex 2 5 8 concave 3 6 9 Source: Parsons 1988. cave in plan (types 3, 6, and 9 in figure 5.8) a. Steep slopes can be stable if the depth to are especially important to identify since bedrock is very shallow. they serve to focus and concentrate both overland and subsurface flow, and lead to relatively higher pore water pressures in the soil. Convergence zones can also have relatively deep soil because of the accumu- lation of eroded material from the hillside above. This topographic control of pore water pressure and soil formation gener- ates areas of increased landslide suscepti- bility that are often associated with hillside hollows. b. Shallow slopes can be unstable if fed by significant subsurface water flow from upslope convergent topography. FI G U R E 5.9  Example of a tropical hillslope profile illustrating Although one or two specialized, algo- common weathering features rithm-based approaches are available for shallow determining topographic convergence (see, weathering pro le deep e.g., Quinn et al. 1991; and Quinn, Beven, and weathering pro le Lamb 1995), they are likely to be insufficiently weathering resolved for the spatial scale of such features colluvium grades in dense urban communities. V/VI III/IV Ask the community about soil depths—how I/II deep house foundations are, whether they are on bedrock, and what soil conditions were notional scale encountered during construction. Look for 0 500m evidence of erosion and accumulation such as Source: Fookes 1997. exposed bedrock and loose, mixed, or washed soils and stones. 1 8 0    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T Look for seepage zones slope and from top to bottom. Although con- The combination of deep soils and concen- tour maps may give an impression of slope trated water flow in topographic convergence angle, contours may be interpolated, or aver- zones can mean that the ground is wet even in aged over a hillside, and thus can be mislead- the absence of rain. Zones of saturation or ing. An Abney level will give a more accurate seepage of water from the soil provide impor- indication of slope angle changes (see fig- tant evidence of how the slope drains. Some- ure 3.16). times seepage can be observed where there is Be careful: slope angles can be misleading no obvious topographic hollow (figure  5.11). in terms of landslide hazard. Residents can The reasons for this may include a subsurface often associate landslide hazard with steeper drainage pattern that differs from the surface slopes. While this may be true in many cases, it drainage pattern; a change in slope material is important to ascertain whether shallow properties (an interface between soil or rock slopes may in fact pose a greater landslide risk. with differing hydraulic conductivities); or a As an example, the upper slopes in a com- point source of water such as a burst water munity may comprise rock and could be as pipe, septic tank, or household wastewater steep as 45 degrees, while the lower shallower pipe. Ask residents if there are places where slopes might be 20 degrees and comprise a sig- the soil is always wet even when it has not nificant amount of residual and colluvial rained. Look for plants that like wet condi- (accumulated) soil overlying bedrock. If these tions, mossy or mildewed rocks and concrete, shallow slopes lie within a hillslope hollow, saturated soils, or running water emerging at a water (both surface and subsurface) from the point in the soil surface. steeper slopes will be concentrated and will infiltrate the lower slopes. This circumstance Observe slope angles may lead to increased pore pressures and a potentially greater landslide risk on the lower Observe the shape of the slope in terms of 20 degree slopes than on the higher 45 degree slope angle, and how this varies across the slopes. Look carefully at lower, shallow slopes FI G U R E 5.11  Seepage occurring in dry Be sure to map all areas of the hillside with weather conditions where there is no sign of a zone of topographic convergence equal emphasis. Shallow slopes should be seen as areas of potential landslide risk for the rea- sons given above. Look for alterations to natural drainage The development of communities on slopes will inevitably alter the natural drainage pat- tern, either through the deliberate construc- tion of drains or as an unintended consequence of human activities. Look for existing main drains (ones that affect more than one house- hold plot) and determine whether they follow and augment natural drainage routes or change the drainage pattern. Note where drains start and finish, what condition they are in, and whether they connect to other drains or natural ravines. Ask the community how deep the water is in the drains when it rains heavily, and if the drains overflow or leak. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 8 1 It is common for unauthorized construc- runoff, causing water to flow alongside or tion to cause concentrated water flows at spe- under the drain instead of into it (figure 5.12b). cific locations. These point source discharges Summary: Hillside scale features can cause erosion and flooding, and potentially increase landslide risk. When mapping exist- Table 5.3 summarizes hillside scale features to ing drains, look for sections of drain that are include in the community slope feature map. unfinished, unconnected, or broken and to note the effect of the resulting point source 5.4.2 Household scale: Mapping the discharges on slope drainage and stability. detail Houses can create significant point water Once the broad slope characteristics have been sources by discharging gray water (bathroom captured, the mapping team should begin to and kitchen wastewater) and black water (sep- investigate the household-scale influences on tic waste) onto the slope, and rainwater from slope stability and evidence of any potential roofs. Where there is a piped water supply to instability. This stage of the mapping process houses this can significantly increase the vol- provides a vital opportunity to meet residents; ume and impact of household water dis- discuss drainage and slope stability issues; and charges. Note the presence of piped water and listen to concerns, priorities, and ideas. Do not evidence of broken or leaking water supply rush this stage, as it is a significant opportunity pipes. to encourage community ownership of the Other structures that change the flow of project while ensuring that any landslide haz- water on slopes are paths and steps (which can ard reduction measures are appropriate both form a preferential flow path for surface water scientifically and socially. runoff, figure 5.12a), and retaining structures Identify the location of each house or walls that can block and divert surface and subsurface flow. Sometimes poorly con- Identify each house on the community map structed drains can act as a barrier to surface and verify that its position is correctly mapped F IG U R E 5 .1 2  Looking for natural and altered slope drainage a. An eroded earth footpath also acts as a drainage b. A drain built in a natural drainage channel with route and causes the lower concrete path to flood. high side walls prevents surface runoff entry. 1 82    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T TAB L E 5. 3  Hillside scale features to mark on slope feature map LOOK FOR ASK ABOUT CAUTION MAP Zones of different Hollows and ridges topography; see Where the water flows Vegetation, structures, figure 5.8 Water convergence, when it rains, where the and contour maps can natural drainage routes, soil is wet even when be misleading. seepage there’s no rain, if drains Human influence can Drainage routes and Main drains, unfinished overflow, whether there change the natural convergence zones; see drains, flow along paths, is a piped water supply… slope and drainage figure 5.8 barriers to drainage, point water sources How deep the soil is, Exposed rock, disturbed The terms people use what the soil is like soils and stones, to describe slope Differences in soil and (strong, soft, clayey, evidence of erosion and materials and their bedrock sandy, stony, disturbed, accumulation properties will vary etc.) Shallow slopes may be Changes in slope angle Zones of different slope more landslide prone and soil/rock evidence angle than steep ones (using a GPS receiver, or by taking compass F IGUR E 5.13  Potential landslide hazard bearings from known fixed points). Take note driver: Cutting platforms to build houses of the location of the house relative to overall topographic and drainage features already mapped. Bear in mind the influences these features are likely to have at the household level, such as whether the household is likely to experience flooding or slope instability, or to contribute water to neighbors farther downslope. It is sometimes helpful to use an aerial pho- tograph for verification. If residents show an interest, the photo can be a good visual tool for initiating discussion on drainage or landslide issues. Note local slope geometry and material In constructing houses on steep slopes, resi- dents may have altered the slope geometry by cutting into the slope or building and back- filling retaining structures (figure 5.13). Look for evidence of altered slope geometry in the and if there are variations or strata. Home- form of steep cut slopes, flat terraced areas owners can provide useful information about (like steps in the slope), and retaining walls. Is the nature of the slope material if they con- there any evidence of weakness or failure of structed the houses themselves. Ask how deep these slopes and structures? the foundations are, what the slope material is If there is an exposed (unvegetated) cut like at different depths, and how deep it is to slope, ascertain if the material is soil or rock, the bedrock. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 8 3 Map drainage at the household level F IGUR E 5.14  Potential landslide hazard driver: Household roof and gray water Having noted the location of a house with discharged directly onto slopes respect to the overall slope topography and drainage patterns, try to establish whether there is any evidence of how these factors may have an impact at the household scale. Incor- porate into the map areas that exhibit • saturation or seepage—evidenced by water- demanding plants, moss, mildewed con- crete, saturated soil, water flowing from cut slopes, damp or flooded foundations; • overland flow (surface runoff )—flattened vegetation and grasses, debris and rubbish carried and deposited by surface flows, eroded soils, undermined buildings and paths; • natural, manmade, or diverted drainage routes—concrete and earth drains, enhanced flow paths such as footpaths, a. Water-demanding plants (dasheen, center) blocked drainage routes; and indicate saturated soil near gray water outflow. • point water sources—leaking water pipes, household water. Identify where the household gray water goes Vulnerable unauthorized communities may have a piped water supply but typically no drainage provision. This situation represents a potentially significant landslide hazard driver that should be carefully reviewed throughout the community, since unmanaged surface water b. Stagnant water on the lower slopes of a can be a major trigger for slope instability. populated hillside indicates soil saturation. Some households may discharge gray water directly onto the slope (figure 5.14), while oth- ers will discharge water into a functional con- crete block drain. Both cases should be indi- cated on the community slope feature map. Potential drainage hazards Households in vulnerable communities will often undertake unauthorized construction work—that is, works that do not comply with planning regulations, structural design prac- c. Shower and laundry water goes straight into the ground. tices, and building codes. Note: Map all sources of household water; a Map any evidence of such structures that MoSSaiC intervention should capture as much of this could affect slope drainage or stability. For water as possible. example, poorly constructed or single-skin 1 8 4    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T (single-block-thick) water tanks that could for a long time—as they will typically recall the easily fail, causing not only flood damage but timing, location, and impact of any past land- also slope instability downslope (figure 5.15). slides and major rainfall events. Such events have a significant effect on residents, and first- hand recollections tend to be precise, making FI G U R E 5.15  Potential landslide hazard them particularly valuable. driver: Failure of poorly designed and constructed water storage structure Evidence of slope movement: Slope features Typical indicators of slope movement include the following: • Undulating or unusual slope profile indica- tive of previously disturbed material • Cracks in the slope (tension cracks), which would indicate recent movement • Unsorted slope materials—soils, stones, boulders, and debris mixed together • Minor slope movement, which could pre- Summary: Household-scale contributors to cede a larger landslide event (figure 5.16). instability Table 5.4 summarizes household-scale con- Larger-scale indicators, such as unusual tributors to slope instability to include in the topography over a whole hillside, are not community slope feature map. always discernible at ground level and can sometimes be identified on aerial photos and 5.4.3 Indicators of slope stability issues accurate topographic maps. Local knowledge of past landslides Evidence of slope movement: Structures Talk to as many residents as possible—espe- Identify and record significant cracks in struc- cially those who have lived in the community tures that indicate slope movement. Try to dis- TAB L E 5.4  Household-scale contributors to slope instability to mark on slope feature map LOOK FOR ASK ABOUT CAUTION MAP Steep-cut slopes, stepped or terraced How the homeowner has constructed the Altered slope geometry slopes, retaining structures house, how deep the foundations are, whether bedrock was The terms people use encountered, what the to describe slope Evidence of deep or Exposed soil and rock soil structure was like materials and their shallow soils properties will vary Main drains, unfinished drains, flow along paths, What happens when it Try to get residents to Water coming from barriers to drainage, rains, where the water be precise about depths upslope evidence of seepage flows from/to, if the or quantities of water ground is always wet Be aware of disputes Household water even when it hasn’t between neighbors Point sources of water sources, leaking pipes, rained about drainage and drainage downslope flooding hazards CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 8 5 leaning. Take note of ruined houses and try to F IG U R E 5 .1 6  Evidence of minor slope find out why they were abandoned: were they movement damaged by previous slope movement? Reported landslide problems If a landslide problem is reported at a particu- lar house, try to determine the cause and scale of the problem. Use the evidence collected at the hillside and household scales (described in sec- tions 5.4.1 and 5.4.2) to look for potential causes of instability such as It is important to map such areas on the • topographic and drainage convergence, drainage hazard plan. • deep or weak soils, • drainage and point sources of water, • landslide problems on the same hillside, tinguish between poor construction and • structural clues, and ground movement, since it is the latter that is • evidence of slope movement. of significance here. Cracks in concrete structures (figure  5.17) Try to ascertain the scale of the unstable may be caused by zone: • historic land movement; • Is the problem localized to the house and augmented by local factors such as drainage • current land movement; from the house or from a point source far- • past seismic events; ther up the slope? • poor construction, shallow foundations, or • Is the problem part of a wider drainage or poorly compacted fill material; or slope stability issue that could affect more than one house? • a combination of all or some of the above. It is important to distinguish between these Determine whether this is truly a landslide causes when developing the slope feature map. issue or if it has another cause. For example, is Look for evidence of structures (such as the reported problem the result of buildings, fences, and retaining walls), trees • undermining of structures through soil ero- and utility poles having been displaced, or sion or flooding due to uncontrolled surface water runoff; or F IG U R E 5 .1 7  Cracks in a wall: Past slope instability or poor construction? • poor construction practices such as cutting a slope too steeply, not compacting the fill/ foundation material sufficiently, not con- structing deep enough foundations, or not using enough cement or reinforcement. Determine whether the cause is an acute (sudden onset) destabilizing event that should be immediately addressed at the source. For example, has there been a sudden change in conditions, such as a burst pipe or rapid exca- vation of the slope for construction? 1 8 6    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T Summary: Evidence of instability level or similar instrument) and the location of slope features and structures (using a compass Table 5.5 summarizes slope instability evi- for triangulation, or a GPS receiver). Try to dence that should be sought when construct- make the map as accurate as possible in terms ing the community slope feature map. of the locations, orientation, and scale of the following (figure 5.18): 5.4.4 Finalizing the community slope feature map • Houses Improve map accuracy • Paths and roads (concrete and unmetaled) • Natural drainage channels and flow paths Augment the map with detailed information • Existing drains on slope angles and topography (using Abney • Other key landmarks or features. TAB L E 5.5  Slope instability evidence to mark on slope feature map LOOK FOR ASK ABOUT CAUTION MAP Undulating or uneven Recollections of Try to obtain several Past landslides and topography, cracks in landslides, recent corroborating accounts evidence of movement the ground changes in the slope, when cracks appeared, have they changed, Poor construction can Cracks, leaning what did this coincide Structural indicators of also result in cracks or structures with (rainfall, earth- instability subsidence quakes, construction…) Localized causes and Erosion and flooding When, how this Household-scale wider causes—use the may be reported as occurred indicators of instability map for evidence landslides FI G U R E 5.18  Example of a community slope feature map showing household-level detail Nb. piped water supplied but no sewerage water from road (cracked drains)... evidence of GPS 001 provision, some houses have roof gu ering - no drains cracks in road bedrock outcrop Retaining walls GPS 002 - no weep holes in GPS 003 dra ept erc 0m) ial int ° (~7 ent 70 pot oute: r residual soil up to 4m deep built on failed material (approx depth > 6m) multiple minor failures GPS 004 wooden in cut slopes (Oct ’09) houses drainage lines tension cracks previously failed material and seepage convergence zones N (>1m deep) ...saturated contours changed due previous landslides with no de ned drainage to landslide debris cut slopes (>50°) channel ravine Note: See original base map (figures 4.6 and 5.7), subsequent slope process zone map (figure 5.21) and initial drainage plan (figure 5.32). CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 8 7 It is important that the slope feature map be • Additional evidence of seepage that was not accurate since it will form the basis of the ini- previously visible tial drainage plan (section 5.7) and be used to • Additional comments, recollections, and indicate the scope of the construction works observations from residents that the rain- (e.g., potential drain lengths and alignments— fall event may prompt chapters 6 and 7). Once this drainage concept has been agreed upon in principle, more pre- Evaluate the effect of publicly supplied piped cise measurements may be taken for the pur- water pose of preparing work packages and contracts and for developing the final drainage plan for If houses are provided with an affordable (and implementation. reliable) piped water supply but no drains, this can significantly increase the volume of water Repeat the survey at least three times infiltrating the slope and reduce slope stability. Even for the most experienced mapping team, In densely populated urban areas, the total it will not be possible to identify or appreciate annual water supply to a community can all the slope features relating to landslide haz- sometimes equate to the total annual rainfall— ard and drainage issues in a particular commu- effectively doubling the volume of water the nity in just one or two visits. slope receives. Undertake the mapping process over the Note whether there is a piped water sup- course of at least three walk-through surveys. ply and if households are discharging gray In particular, develop a comprehensive under- water directly onto the slope. Use an aerial standing of the relationship between the photo or the community slope feature map topography, soil water convergence, and other (to which house locations should now have slope processes based on direct observations been added) to estimate the potential scale of and information obtained from as many resi- the household gray water contribution—the dents as possible. denser the housing stock, the greater the pro- portion of surface water derived from house- Visit during rainfall holds. Rainfall events can reveal additional drainage Other effects of piped water supply to features, providing important information for include on the map include the following: understanding potential landslide causes and • Locations of burst or leaking water pipes configuring landslide hazard reduction mea- sures. If at all possible, the mapping team • Locations where water supply pipes have should visit the community during or immedi- been laid in existing drainage routes affect- ately after heavy rainfall to confirm that rele- ing drain capacity or causing an obstruction vant drainage processes have been included in (figure 5.19) the map. During rainfall events, observe whether surface water runoff follows the drainage lines 5.5 QUALITATIVE LANDSLIDE that have already been mapped and/or HAZARD ASSESSMENT whether there are additional flow routes. Look for the drains that are flowing (noting those 5.5.1 Landslide hazard assessment for that are flowing near, at, or over capacity) and MoSSaiC projects areas of uncontrolled surface water flow or flooding. Also note the following: The community slope feature map (figure 5.18) should now contain sufficient information to • Flows along footpaths and roads allow a qualitative assessment of the landslide • Areas of flow convergence and concentra- hazard. This section provides guidelines for tion the initial assessment of the dominant slope 1 8 8    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T FI G U R E 5.19  Piped water supplied to unauthorized communities a. Water meters allow an estimation of the volume b. Water supply pipes may have been laid in supplied to the community. drains for ease of installation, thus reducing drain capacity. • Engineers, works supervisors, and contrac- stability controls within a community. In par- tors will need a basis for understanding the ticular, the landslide assessment and engineer- design and specification of the works. ing task team should evaluate the extent to which slope instability is dominated by sur- • Decision makers involved in funding proj- face water infiltration. This will indicate ects and government agencies will have to whether a MoSSaiC project to improve surface be able to justify community activities and water management might be effective in expenditures. improving slope stability. Section 5.6 provides scientifically based tools and methods to assist The qualitative landslide hazard assessment in making this assessment. process Importance of justifiable measures Figure 5.20 illustrates a typical workflow and Providing a scientifically based justification related decisions in the interpretation of the for landslide hazard reduction measures is community slope feature map. The aim is to important for several reasons: evaluate the relative degree of landslide haz- ard and the potential causes and solutions, • Any physical works claiming to reduce thus allowing identification of cases where landslide hazard (i.e., reduce the likelihood MoSSaiC interventions are likely to be appro- of landslide occurrence) should be targeted priate. at the specific causes of the landslide haz- ard. 5.5.2 Identify landslide hazard zones • To facilitate community participation, Begin by identifying the various slope pro- there should be an explanation of the sci- cesses, landslide hazards, and drainage zones ence behind the proposed intervention. within the community. From this, produce a CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 8 9 F IG U R E 5 . 2 0  The qualitative landslide hazard assessment process COMMUNITY- Community slope feature map BASED MAPPING completed (SECTIONS 5.3, 5.4) Yes  Slope process zones identified CASES WHERE A MoSSaiC Yes INTERVENTION IS NOT LIKELY TO BE APPROPRIATE  There is evidence of landslide Landslide hazard is likely to be susceptibility No  low Yes  More than one or two households are likely to be exposed and vulnerable to Individual households might landslide hazard, and housing require standard engineering density is sufficiently high to No  measures for localized make a communitywide stabilization of slope landslide hazard reduction project relevant Yes QUALITATIVE LANDSLIDE  HAZARD The landslide hazard is not due Acute (sudden) destabilizing ASSESSMENT to an obvious isolated or events should be addressed (SECTION 5.5) sudden event (e.g., burst pipe, No  immediately (e.g., fix broken slope excavation) pipes, retain excavations) Yes  Initial map interpretation The landslide hazard type and suggests the type of landslide is rotational or translational in No  mechanisms are different (such as rock falls, debris flows, lahars) weathered material Yes  Initial map interpretation The landslide hazard may be suggests surface water dominated by other causes infiltration is a dominant No  (such as earthquakes or regional mechanism for landslide hazard groundwater rise) Yes  A MoSSaiC project is likely to be effective in reducing PHYSICALLY landslide hazard in this BASED LANDSLIDE community HAZARD ASSESSMENT Carry out quantitative (SECTION 5.6) physically based landslide hazard assessment to confirm this assessment 1 9 0    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T slope process zone map, based on the commu- review observations of the influence of surface nity slope feature map and confirmed by addi- water infiltration including the following: tional field observations. • Topographic controls on drainage Slope process zones typically take the fol- lowing forms: • Natural flow paths and alterations of these paths • Steep rocky slopes with no soil, relatively low landslide hazard, but significant gener- • Seepage ation of surface runoff to the slope below • Condition and location of drains (good, (from houses and during rainfall) broken, unconnected, poorly constructed, • Moderate slope angle, midslope position, leaking, insufficient capacity, blocked) receiving surface runoff from the slope • Household-scale influence on drainage pat- above, with significant topographic conver- terns gence, deep soils, and high landslide hazard • Piped water supply • Lower slope locations, with shallower angles and deep soils, relatively low land- • Previous rainfall-triggered landslides slide hazard, but issues with saturated soils • Observed effects of rainfall on the slope. and flooding due to drainage from slopes above Interpret the influence of surface water • Known areas of previous instability infiltration on slope stability for each of the slope process zones and add to the zone • Areas with no soil water convergence and description as shown in the right-hand col- perceived low landslide hazard umn of table 5.6. • Ravines and natural channels with steep If the interpretation of the slope feature banks prone to undercutting and landslides map and slope process zones is that surface during heavy rainfall runoff events (poten- water is a dominant mechanism for landslide tial for increased channel discharge if new hazard, this suggests a MoSSaiC drainage proj- drains are built farther up the slope). ect would be appropriate. In table 5.6, every zone except Zone D would benefit from some Figure 5.21 presents a typical slope process form of improved surface water management zone map and an interpretation of the slope to reduce landslide hazard. features shown in terms of the associated The decision to implement a MoSSaiC proj- landslide hazard. ect should only be taken if sufficient scientifi- cally based justification can be provided. 5.5.3 Identify the dominant landslide Therefore, this initial landslide hazard assess- mechanisms ment should be tested using the tools described Many different and often highly localized pro- in section 5.6. cesses can be involved in determining land- slide hazard (chapter  3). Unauthorized con- struction of high-density housing on slopes 5.6 PHYSICALLY BASED changes local drainage and surface water infil- LANDSLIDE HAZARD tration processes and may increase the land- ASSESSMENT slide hazard. For each slope process zone, and for the 5.6.1 Models slope as a whole, experts in the landslide assess- ment and engineering task team should have A range of quantitative, physically based mod- identified the physical processes likely to affect els can be used to provide the scientific justifi- slope stability (figure 5.21). The team should cation for a MoSSaiC project. It is important CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 9 1 F IG U R E 5 . 2 1  Example of a slope process zone map with supporting observations and interpretations 1 0 10 80 ZONE E ZONE B ZONE D 60 ZONE C ZONE A LOWER SLOPE ZONE F cross-sections for analysis 60 slope process/drainage zones 100 previous landslides FIELD OBSERVATIONS AND INTERPRETATION OF THE INITIAL INTERPRETATION OF ZONE SLOPE FEATURE MAP RELATIVE LANDSLIDE HAZARD Planar slope topography with multiple cut slopes and Moderate landslide hazard—poten- several associated minor slides tial for further cut slope failures A Dense housing with incomplete or broken surface water drains Highly convergent topography with previous major High landslide hazard—likely landslide and deep accumulation of debris. Some houses reactivation of existing landslide rebuilt on debris. debris by rainfall and surface runoff B Higher-density housing adjacent to debris—multiple cut (several houses exposed); multiple slopes, incomplete or broken drains and retaining walls smaller failures of cut slopes and retaining walls also likely Significant surface runoff and seepage Small-scale convergent zones due to alteration of Moderate landslide hazard—poten- topography and drainage by house construction tial reactivation of failed material in Multiple small slides and tension cracks multiple minor slides behind C individual houses Dense housing with incomplete drains and highly altered natural drainage pattern leading to convergence at multiple locations Steep planar topography with very shallow soils/ Relatively low landslide hazard bedrock outcrops D Significant surface runoff (including runoff from road and roofs) but relative stability Small-scale convergent zones aggravated by cut slopes Moderate to high landslide hazard— and altered drainage in cut slopes and wider convergent E zone adjacent to lower footpath Minor cut slope failures exacerbated by discharge of roof water into soil and poorly designed drains Lower slope—deep soils saturated by infiltration of Moderate to high landslide hazard— water from upslope likely triggering of new landslides at F Tension cracks indicate instability base of slope due to high pore pressures in saturated material 1 92    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T TAB L E 5.6  Interpreting the influence of surface water infiltration on slope stability for different slope process zones FIELD OBSERVATION AND INTERPRETATION OF INFLUENCE OF SURFACE WATER ZONE SLOPE FEATURE MAP INFILTRATION Planar slope topography with multiple cut slopes and Household water and incomplete several associated minor slides drainage network directly affecting A Dense housing with incomplete or broken surface water slope stability at several locations drains Highly convergent topography with previous major Significant surface water runoff landslide and deep accumulation of debris. Some houses from upper slope area and road rebuilt on debris. likely to be causing saturation of B Higher-density housing adjacent to debris—multiple cut previous landslide debris slopes, incomplete or broken drains and retaining walls Highly altered drainage network and Significant surface runoff and seepage household water causing localized instability and flooding Small-scale convergent zones due to alteration of Household water and incomplete topography and drainage by house construction drainage network directly affecting Multiple small slides and tension cracks slope stability in areas of conver- C gence Dense housing with incomplete drains and highly altered natural drainage pattern leading to convergence at multiple locations Steep planar topography with very shallow soils/ Surface water infiltration probably bedrock outcrops not an issue for slope stability D Significant surface runoff (including runoff from road and roofs) but relative stability Small-scale convergent zones aggravated by cut slopes Household water and incomplete and altered drainage drainage network directly affecting E Minor cut slope failures exacerbated by discharge of slope stability at several locations roof water into soil and poorly designed drains Partial reactivation of previous failures observed during rainfall Lower slope—deep soils saturated by infiltration of Surface water infiltrating upper F water from upslope slopes is likely to be a significant Tension cracks indicate instability cause of instability that the selected model can account for the MoSSaiC project with available expertise, roles of surface water infiltration and pore data, and software. water pressure in slope stability, and be used to It is worth noting that in the field of hydrol- confirm whether improved surface water man- ogy, many models are, as Lin et al. (2006) state, agement is likely to reduce landslide hazard. either “too good to be real” (the model is over- Table 5.7 identifies two types of scientific simplified and fails to reflect reality) or “too models that are relevant for assessing land- real to be good” (detailed input data require- slide hazard drivers. Chapter 6 introduces four ments render the model impractical). Models additional calculations for the quantitative are inevitably a compromise between the assessment of surface water runoff, piped search for perfection, the complexity of real water supply, roof water interception, and slopes, and the perennial availability of only at required drain dimensions. best partial data. The models identified in this The models outlined in this section will book seek to achieve that balance but should require some level of technical knowledge. be viewed alongside alternative quantitative The MCU should identify models that balance procedures depending on local conditions of the need for scientific justification of a data availability and expertise. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   1 93 TA BLE 5 .7  Quantitative physically based landslide hazard assessment models appropriate for use as part of MoSSaiC BOOK MODEL PURPOSE EXAMPLE SOURCE SECTION Simulation of the physical processes See http://www.ggsd.com for a 3.6.1; 5.6.3 affecting slope stability comprehensive listing of slope Slope stability software Identification of dominant landslide stability causes model Landslide hazard prediction (probabil- ity, magnitude, location) Assessment of the role of negative Resistance envelope calculation in 3.6.2; 5.6.4 Resistance pore water pressure (matric suction) in Anderson, Kemp, and Lloyd (1997, envelope controlling slope stability 14–20) Note: For each purpose, many alternative tools may be applicable. 5.6.2 Data for slope stability models • Additional laboratory and field measure- ments—e.g., detailed survey of slope cross- Physically based slope stability software such section using a total station or similar as CHASM (Coupled Hydrology And slope equipment, sampling and shear box testing Stability Model), which was introduced in sec- of soils. tion 3.6.1, is designed to enable assessment of the stability of a slope and to identify the Figure 5.22 shows a typical slope selected underlying hydrological and geotechnical pro- for stability analysis. Note the density of veg- cess controls. etation and housing which obscures the slope Whatever form of slope stability analysis is features and ground surface. Engineers and used, it is likely that three groups of input data technicians should not be deterred by this will be needed: slope cross-section configura- apparent complexity. Much of the initial data tion, soil and weathered slope material geo- required for landslide hazard analysis is often technical and hydraulic properties, and readily estimated during the community sources of water added to the slope. mapping stage. For a more detailed discus- For each group of data, table 5.8 lists typical sion of each of these parameters, see sec- parameters required for slope stability analy- tion 3.5. sis. These data will need to be estimated, col- lected, or measured in three ways: 5.6.3 Using slope stability models Various slope stability assessment methods • Community mapping process—e.g., slope were introduced in chapter 3. Deterministic angles and distances along the cross-sec- models based on limit equilibrium methods tion selected for analysis, evidence of soil were highlighted as an accessible and appro- and water table depths, weathering grades priate tool for use at the community scale. of exposed materials Such models can help engineers identify the • Desk study—review of previous reports current slope stability state, the dominant and scientific or engineering texts; e.g., physical mechanisms causing instability, and local rainfall records, water supply records, the potential effectiveness of slope drainage typical soil geotechnical and hydraulic measures. The following four steps (after Hol- characteristics for relevant weathering combe et al. 2011) have been successfully grades applied in using CHASM for this purpose: 1 9 4    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T TAB L E 5.8  Typical input parameters and their measurement for slope stability analysis PARAMETER SIMPLE ESTIMATION METHOD MORE PRECISE MEASUREMENT METHOD Slope Abney level measurement Detailed topographic survey profile Contour maps Existing high-resolution digital elevation models geometry SLOPE CROSS-SECTION (e.g., generated using LiDAR) CONFIGURATION Soil On-site inspection of any exposed soils and Search for any previous detailed reports from depths bedrock geotechnical engineers that might give borehole and strata Talk with residents who may have knowledge of data from the area soil strata depths, especially if they have carried Carry out bore-hole analysis out excavations for house construction Depth to On-site inspection of any seepage from the slope Search for any previous reports that might contain water Talk with residents who may have knowledge of field determinations of depth to water table table depth to water table Material On-site inspection to identify material weathering Search for any previous reports of the area that SOIL AND WEATHERED SLOPE MATERIAL strength grade as a guide to relative material strength. might contain laboratory or field determinations of GEOTECHNICAL AND HYDRAULIC Comparison with grade-strength relationships in soil strength in terms of cohesion (c') and phi (Φ') research or engineering reports/textbooks (see figure 5.27) See Fookes (1997); GCO (1982) Take samples of the material and carry out shear PROPERTIES box testing in a laboratory. Material On-site inspection to identify material weathering Search for any previous reports of the area that hydraulic grade as a guide to relative material permeability might contain laboratory or field determinations of properties Comparison with grade-permeability relationships in hydraulic conductivity (Ksat) and suction-moisture research or engineering reports/textbooks curves See Ahmad, Yahaya, and Farooqi (2006); Carter and Idealized curves can be found in many standard Bentley (1991) soil science or engineering textbooks (Anderson et al. 1985; van Genuchten 1980) Piped On-site inspection and information from residents Obtain water company data on average supply per water to estimate relative contribution of piped water household over a specific time period; multiply by SOURCES OF WATER ADDED TO SLOPE compared with rainfall the number of households in the community to Aerial or satellite photographs to enable calcula- obtain the total amount of water supplied to the tion of housing density, and hence potential slope for that period contribution of piped water Rainfall Use records of a specific rainfall event known to Obtain rainfall intensity/duration/frequency data to have caused landslides in the local area allow design storms to be specified (e.g., 1-in-100- year 24-hour event with an intensity of 12 mm/h) regardless of the software selected, the steps FI G U R E 5.2 2  Typical slope selected for stability analysis described here should assist in the model application. Step 1: Build the input files for the simulation On the plan, identify the location of slope cross-sections selected for analysis. Two sec- tions have been identified in the example in figure 5.23. Section X1-X2 encompasses several houses in an area identified during the map- ping process to be potentially susceptible to a single large landslide. Y1-Y2 represents part of the slope in which there was drainage conver- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 9 5 F IG U R E 5 . 2 3  Zone E of the example community with two slope cross-sections marked for analysis X1 road concrete house concrete + wooden house wooden house roads, paths, or steps existing landslides Y1 cross-sections for analysis Y2 N X2 ravine approx 50 m Note: See figure 5.21. —— If CHASM software is used, these data gence and several cut slopes that showed signs are encapsulated in the geometry input of instability. The following considers the file. example of section X1-X2. b. Define the material geotechnical and a. Draw the slope cross-section. hydraulic properties. —— Draw the slope cross-section to scale by —— Define the properties required by the reading contours from an accurate topography map or by using field mea- model for each of the material types surements and applying trigonometry. identified in the slope cross-section. —— Identify how many material types are —— If CHASM software is used, the data present (ranging from weathering grade requirements are as follows: saturated VI to grade I material—i.e., residual and unsaturated bulk density, saturated soils to bedrock, figure 3.18) based on moisture content, cohesion, angle of observations, residents’ knowledge, internal friction, and suction-moisture local expert knowledge, and previous curve coordinates. These data are encap- reports. sulated in the soil input file. —— Estimate the depth and angle of the dif- c. Define the boundary conditions. ferent material strata—again using —— In dynamic hydrology models, the observations, residents’ knowledge, local hydrological boundary conditions rep- expert knowledge, and previous reports. resent the initial conditions and the Draw the strata on the cross-section. behavior of the water at the edge of the —— Estimate the depth to the water table in model domain. Boundary conditions a similar way and add to the cross-sec- can include initial surface suction con- tion. ditions, rainfall, point water sources, 1 9 6    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T evaporation rates, and groundwater flow. F IGUR E 5. 24  Model configuration and predicted location of landslides —— Rainfall conditions should be defined for road slip surface of 2nd landslide each simulation time-step according to 80 m the particular scenario to be tested. Typ- slip surface of 1st landslide ically, the modeler will define an initial profile from contours soil dry period to allow the model hydrology actual profile with cut slopes to become numerically stable, and then 40 weathered impose a design storm of a known inten- ravine material sity, duration, and return period. estimated water table See chapter 3 (section 3.6.1) for further guidance. bedrock Y Y 1 2 0 Step 2: Run the model to simulate current 0 40 80 120 m stability conditions X X 1 2 Simulate the effect of the chosen rainfall event on the stability of the slope. If possible, first run a rainfall scenario that is known to have Limit equilibrium slope stability models do caused previous landslides at this location. not account for the dynamics of landslide run- Verify that the model represents the slope pro- out. Landslide runout (travel distance) can be cesses realistically by carrying out a back anal- estimated using empirical relationships (see Fin- ysis—examining water table changes, pore lay, Mostyn, and Fell 1999 for a simplified method water pressure patterns, and factor of safety for cut slope failures) or local expert knowledge. response. If the simulations do not appear Step 4: Run simulations for different drainage physically realistic, check the input data and scenarios account for any uncertainties (see sec- tion 5.6.5). If the model indicates that the slope has an Once satisfied with the model behavior, run unacceptable level of landslide hazard (in a sequence of rainfall events of increasing terms of probability or magnitude), the next intensity or duration to determine the associ- step is to try to identify measures that might ated factor of safety. A factor of safety of less reduce this hazard. than 1 implies potential slope failure. Record Based on the earlier qualitative assessment the minimum frequency rainfall event that is of the role of surface water infiltration for the predicted to cause a landslide and the position relevant zone of the community (table 5.6), run of the resultant failure surfaces (figure 5.24). the model with different surface water man- agement options: Step 3: Plot predicted landslides on the map • Interception of rainfall runoff, repre- If the analysis is carried out using CHASM or a sented as a percentage reduction in rain- similar limit equilibrium-based model, the fall—based on an estimation of how much slope and any landslides are likely to be repre- runoff could be intercepted by new drains sented in two dimensions (i.e., a cross-section of the slope). Mark the location of the crest • Rainwater capture from roofs, also repre- and toe of any predicted landslides on the sented as a percentage reduction in rainfall— community map and estimate the width of the based on the area of roofs covering the slope main body of the landslide (figure 5.25) using (e.g., if houses cover 50 percent of the slope, field observations of topographic or geological then assume that completely effective rain- features that would constrain the landslide water capture will reduce the rainfall reach- geometry. ing the slope surface by 50 percent) CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 9 7 F IG U R E 5 . 2 5  Predicted landslide locations and estimated runout X1 road concrete house concrete + wooden house wooden house e roads, paths, or steps slid d 2nd lan existing landslides Y1 e cross-sections for analysis slid 1st land predicted landslides X1-X2 predicted houses lost predicted houses damaged and possessions lost Y2 N X2 ravine approx 50 m Note: House construction types and locations allow very basic estimation of impact. • Capture of household gray water (piped 1-in-10-year 24-hour rainfall on the factor of water), represented by a reduction in the safety at cross-section X1-X2, where F ≤ 1 indi- volume of water discharged onto the slope cates slope failure for the no intervention case. from household point water sources. Surface water management in this example increases the factor of safety to 1.1 (marginally Compare the change in the factor of safety stable); that is, to make the slope fail would for each of the surface water management sce- require a 1-in-100-year rainfall event. narios. Figure 5.26 illustrates the effect of a 5.6.4 Analyzing the role of pore water pressure FI G U R E 5.26  Predicted improvements in the factor of safety for different drainage interventions Negative soil pore water pressures can help maintain slope stability in certain soils found 1.25 1-in-10-year rainfall event in the tropics. Loss of negative pore pressures factor of safety (F) 1.20 due to rainfall infiltration can therefore poten- 1.15 tially reduce slope stability. It is important to 1.10 understand the response of a particular soil to 1.05 infiltration to assess whether the stability of a 1.00 slope requires the maintenance of negative 0.95 pore pressures or whether the slope is stable 0 100 200 300 for a certain level of positive pore pressures. time (hours) Resistance envelopes allow such a determina- roof water + 50% surface water interception tion to be made (for method, see section 3.6.2), roof water interception no intervention (equivalent to 1-in-100-year thereby helping the team determine whether event with roof water interception) surface water management is an appropriate strategy for improving slope stability. 1 9 8    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T 5.6.5 Uncertainty in physically based —— The process of dividing a slope profile landslide hazard assessment into a mesh of discrete elements and solving physics-based equations at dis- There are limitations and uncertainties associ- crete time-steps results in an approxi- ated with the application of slope stability mation of physical reality. models and resistance envelopes: “In soil —— Physics-based equations incorporated mechanics the accuracy of computed results into a dynamic model will often exhibit never exceeds that of a crude estimate, and the rounding errors. principle function of the theory exists in teach- ing us what and how to observe in the field” —— Interactions between model compo- (Terzaghi 1936, 13). Some of these issues are nents and sensitivities to different described below (after Christian, Ladd, and parameters are not always known or pre- Baecher 1994; Malkawi, Hassan, and Abdulla dictable. 2000; Sidle, Pearce, and O’Loughlin 1985). Acknowledging sources of uncertainty is a • Representation of slope parameters (espe- central element in correctly interpreting phys- cially with respect to the slope material) ically based numerical models. Be careful not —— A high degree of natural anisotropy and to overinterpret simulation results. Physically heterogeneity in soil and weathered based numerical models rely on spatial and material properties (i.e., bulk density, temporal data that may be difficult to acquire, strata depth and geometry, geotechnical so assumptions of both data input and model and hydraulic parameters) means that the structure have to be made. Thus, as Fellin et al. precise spatially distributed values for (2004, 14) note, “results from the most sophis- these properties cannot be fully known. ticated contemporary models will remain ‘crude estimates.’” —— Each modeler will configure soil param- Two specific areas of uncertainty of which eters differently given different methods the landslide assessment and engineering of data collection, analysis, and interpre- task team should be aware are discussed tation. below: uncertainty in soil parameters and • Representation of physical processes uncertainty associated with model formula- tion. —— Static slope stability analysis methods do not account for dynamic slope hydrology. Uncertainty in soil parameters —— Temporal changes such as the effects of Soil properties lack uniformity, even within soils of the same type or weathering grade. deforestation or downslope creep on soil Figure 5.27 shows variations in material strength are difficult to estimate and strength properties (cohesion and angle of incorporate. internal friction) which have been measured —— Detailed knowledge of the principle fac- using a shear box and classified by weathering tors leading to failure may be lacking, grade. This plot was derived by consolidating especially with respect to local factors data from numerous materials reports from a affecting pore water conditions. small island state in the Caribbean, and shows the degree of variability that can exist within —— Postfailure deformation, movement, and single material weathering grades. deposition of the failed material (run- The cohesion and angle of internal friction out) are difficult to represent. values throughout a slope can only be deter- —— Most landslide models represent three- mined at a small number of locations com- dimensional phenomena in two dimen- pared to the number of potential cells a model sions. is capable of representing (0.1 percent repre- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    1 9 9 F IG U R E 5 . 2 7  Example of heterogeneity in angle of internal friction and cohesion, classified by weathering grade 100 Grade I cohesion range 100–7,000 kPa 80 cohesion (kPa) 60 Grade V Grade II 40 Grade III 20 Grade IV Grade VI 0 0 10 20 30 40 50 60 angle of internal friction (degrees) Grade I Grade III Grade V exponential regression of c and Grade II Grade IV Grade VI Ф mean values for each grade Note: For weathering Grades IV, V, and VI, the boxes represent 2 standard deviations from the respective grade means. sentation would be a high value). Uncertainty F IG UR E 5. 2 8  Number of geotechnical in model parameters must be recognized if engineers selecting various friction angles as models are used for inferential purposes (see characteristic for a given set of soil strength Anderson and Bates 2001 for a more substan- data tive discussion on model validation). 50 A second source of uncertainty in soil prop- erties derives from the fact that experts will 40 interpret soil data differently when selecting 30 parameters for stability analysis. In a study by number Fellin et al. (2004), a set of four soil strength 20 values, determined from four different sam- ples of the same soil type and location, were 10 given to 90 geotechnical engineers. Each engi- neer was asked to select the characteristic 0 25 26 27 28 30 32 34 35 shear strength parameters to use in a stability friction angle (degrees) analysis. The friction angle deemed to be char- Source: Fellin et al. 2004. acteristic ranged from 25 degrees to 35 degrees (figure 5.28), while the range in cohesion was from 0 to 27 kN m−2 (with a modal group of a specific formulation and approximation of 10 kN m−2). Thus, even with soil data available, the processes it seeks to represent. Even if the the interpretation and final selection of a input data for a slope stability model are parameter value can differ quite appreciably specified exactly, the predictions of that among experts. model can be expected to deviate from reality for the reasons given at the beginning of this Uncertainty associated with model formulation subsection. Increasingly complex models are being devel- There are many choices to be made in oped for geotechnical analysis. However model design, including which failure mecha- complex a slope stability model is, it remains nisms to employ, what space-time resolution 2 0 0    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T to use, and how to represent unsaturated soil water conditions. There can thus be multiple F IGUR E 5. 2 9  Effect of soil parameter variability on CHASM simulation results feasible versions of reality (see Beven 2006 for a full discussion of this issue) and many mod- a. Factor of safety els from which to choose. Moreover, modelers 3,000 almost never declare a model to be invalidated, 2,500 since most models have enough adjustable 2,000 frequency parameters to fit the available observed data. 1,500 The modeler must then distinguish between an apparent fit, based on artificial manipula- 1,000 tion of an overparameterized model, and one 500 based on an accurate representation of process 0 (NRC 1990). 0.0 0.5 1.0 1.5 2.0 factor of safety Representing uncertainty b. Failed mass Data and model uncertainty can be repre- 6,000 sented in simulations by repeatedly running 5,000 the model using a range of input parameters values to reflect parameter uncertainty. In frequency 4,000 slope stability modeling, such multiple real- 3,000 izations yield a distribution of factor of 2,000 safety values and related outputs (fig- 1,000 ure 5.29). For a given test slope and a sophisticated 0 0 50 100 150 200 representation of uncertainty relating to all mass × 103 (kg) the model parameters, Rubio, Hall, and Ander- son (2004) showed that CHASM yielded a fac- c. Depth of slip surface tor of safety distribution in the range of 1.0— 7,000 1.8. Significantly, the variance in the effective 6,000 angle of internal friction dominated the vari- 5,000 ance in factor of safety (accounting for 89 per- frequency 4,000 cent of the variance). Thus, while individual 3,000 components of these models (such as the 2,000 unsaturated zone water retention, or the 1,000 Bishop slope stability submodels in CHASM) 0 are generally well understood, their emergent 0 1 2 3 4 5 6 behavior may be more difficult to diagnose. depth (m) The MCU, in general, and the landslide Source: Hamm, Hall, and Anderson 2006. assessment and engineering task team, in particular, must be aware of the issues 5.6.6 Interpreting physically based entailed in slope stability model selection, landslide hazard assessment results data uncertainty, and the associated model outcome interpretation. It might be useful to For MoSSaiC, the objective of using physically hold a workshop at which colleagues can based slope stability assessment methods is to contribute relevant data sources, understand confirm the degree of landslide hazard affect- data uncertainty, appreciate the consequen- ing a specific zone of the community and to tial uncertainty in numerical modeling, and investigate the main causes and potential solu- share experiences in running software (fig- tions. In particular, these assessment methods ure 5.30). should be used to confirm or reject the hypoth- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 0 1 measures as a means of reducing that hazard. F IG U R E 5 . 30  Slope stability modeling Table 5.9 summarizes this approach. workshop for landslide assessment and This landslide hazard assessment process is engineering task team an iterative one. The simplest approach is to take a known major storm event, run the slope stability model for that event, and then again with 75 percent, and again with 50 percent, of recorded rainfall levels. Simply put, the result- ing change (potential increase) in the factor of safety will provide a broad indication of whether such reductions in surface water infiltration would be likely to result in a sig- nificant reduction in landslide hazard. If the simulations indicate no apparent reduction in hazard (no increase in the factor of safety), this esis that surface water infiltration is the domi- would suggest that a MoSSaiC intervention nant destabilizing influence, thereby demon- would probably not be appropriate. Con- strating the potential effectiveness of rainfall versely, a significant increase in the factor of interception and surface water management safety when effective rainfall is reduced would TA BLE 5 .9  Summary of the physically based landslide hazard assessment process LOOK FOR METHOD CAUTION UNCERTAINTY Select a method that Be aware of uncertain- Quantitative, physically Ask government depart- accounts for the ties due to the way the based methods, models, ments, agencies, relevant slope processes model represents (or and expertise already consultants, and (landslide type, material omits) physical available locally colleges or universities type, hydrological processes processes) Make sure that the Be aware of natural Acquire data on slope Slope data that can real- method or model parameter variability, geometry, soil strata, istically be acquired for selected is realistic in sampling, and measure- water table, soil the available methods terms of data availabil- ment errors (or biases) properties, water supply and models ity and level of and differences in (see table 5.8) expertise expert opinion Assess stability with Be aware of the effect Represent uncertainty respect to different that the results of this by applying the method The current slope stabil- conditions; use rainfall analysis could have or model several times ity state and the events ranging from when made known to with varying input physical processes that those expected to occur local residents, parameters; be honest have the greatest every year to more landowners, govern- in communicating the influence on stability intense or longer-dura- ment representatives, level of uncertainty in tion events with lower and the media; use model results return periods appropriate safeguards. Represent uncertainty The potential effective- Account for the likely To incorporate these in the effectiveness of ness of surface water effect of rainfall runoff surface water manage- surface water manage- management for interception (by drains ment approaches, it ment measures by reducing landslide and roof guttering) and may be necessary to applying the method or hazard (look for reduction in household use a proxy (such as model several times improved slope stability, gray water added to the reducing rainfall input with varying reductions lower water table in the slope by a certain percentage) in rainfall and point model) water sources 2 02    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T indicate that a MoSSaiC intervention could be • Household-scale features and influences on appropriate. slope processes (local slope geometry— The landslide assessment and engineering cuts, fills, and retaining structures, house- task team should communicate the results of hold-scale drainage lines and point water the quantitative landslide hazard assessment sources, evidence of previous or potential clearly to the MCU so that nonexperts can landslides) understand and make decisions about the • Quantitative landslide hazard assessments project. Be transparent about uncertainties in (slope stability modeling, analysis of the the specific values of slope factor of safety or effect of piped water and rainfall, assess- percentage changes in stability for different ment of suction control). drainage interventions. Importantly, identify the overall trends in the model results to con- Building on the initial qualitative landslide vey whether surface water infiltration is a sig- hazard assessment process outlined in fig- nificant driver for the landslide hazard, and ure 5.20, figure 5.31 consolidates and presents whether drains would be likely to improve the complete landslide hazard assessment and slope stability. decision-making process described in this If physically based simulations support a chapter. MoSSaiC intervention, continue to use the The final phase of the community-based model to determine the specific impact of sur- landslide hazard mapping process described face water management. Chapter 6 details the in this subsection entails the following: components of such an intervention: the vari- • For each of the slope process and landslide ous configurations of contour (intercept) hazard zones in the community, confirming drains and downslope drains; and the installa- the potential surface water management tion of downpipes, guttering, gray water drain option likely to be most effective in improv- pipes, and related infrastructure. Once a ing the slope stability and drainage issues detailed drainage design has been undertaken, within each hillside zone the simulations can be rerun with more pre- cise rainfall reduction figures that reflect • Sketching potential new drain locations on anticipated rainfall capture data. an initial drainage plan and taking photos of these locations • Assigning priorities to the various drainage 5.7 PRIORITIZE ZONES FOR interventions based on relative landslide DRAINAGE INTERVENTIONS hazard and likely effectiveness If the quantitative, physically based landslide • Gaining consensus from all stakeholders on the initial drainage plan. hazard analysis indicates that a MoSSaiC proj- ect is appropriate, the next step is to prioritize zones of the community for specific drainage 5.7.1 Assign a potential drainage measures. The landslide assessment and engi- intervention to each zone neering task team should integrate all the Each landslide hazard and drainage zone will information generated by the mapping and require a slightly different intervention to modeling processes described in this chapter: reduce landslide hazard; some zones may not • Hillside-scale slope features and processes need any intervention at all. (topography, slope angles, locations of The community needs to understand the deeper soils versus bedrock, convergence rationale behind the identification of the dif- zones, major natural and altered drainage ferent zones, and therefore the purpose and lines, evidence of past or potential land- suitability of the different categories of inter- slides) vention proposed for each zone. Some areas of CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 0 3 FI G U R E 5. 3 1  Complete community-based landslide hazard assessment process for MoSSaiC interventions COMMUNITY- Community slope feature map completed BASED MAPPING (SECTION 5.3, 5.4) Yes  Slope process zones identified Yes CASES WHERE A MoSSaiC INTERVENTION IS  NOT LIKELY TO BE APPROPRIATE There is evidence of landslide susceptibility No  Landslide hazard is likely to be low Yes  More than one or two households are likely to be Individual households might require standard exposed and vulnerable to landslide hazard, and housing No  engineering measures for localized stabilization of density is sufficiently high to make a communitywide slope landslide hazard reduction project relevant Yes QUALITATIVE  LANDSLIDE HAZARD Acute (sudden) destabilizing events should be ASSESSMENT The landslide hazard is not due to an obvious isolated or No  addressed immediately (e.g., fix broken pipes, (SECTION 5.5) sudden event (e.g., burst pipe, slope excavation) retain excavations) Yes  Initial map interpretation suggests the type of landslide is The landslide hazard type and mechanisms are No  rotational or translational in weathered material different (such as rock falls, debris flows, lahars) Yes  The landslide hazard may be dominated by other Initial map interpretation suggests surface water No  causes (such as earthquakes or regional groundwa- infiltration is a dominant mechanism for landslide hazard ter rise) Yes  PHYSICALLY BASED The landslide hazard may be complicated by LANDSLIDE HAZARD Slope stability and pore water pressure analysis confirms multiple aggravating factors (human influences, ASSESSMENT that surface water infiltration is a dominant mechanism No  previous earthquakes, groundwater change, (SECTION 5.6) for landslide hazard deforestation, construction) Yes  Possible locations for intercept and down-slope drains Constructing new surface water drains is not likely can be identified and an initial drainage plan agreed with No  INITIAL to be feasible in this community the community ASSESSMENT OF SLOPE DRAINAGE Yes FEASIBILITY  (SECTION 5.7) Milestone 5  Calculations confirm the effectiveness of new drains to The landslide hazard may not be addressed by intercept surface water runoff and convey runoff, No  surface water management alone roof-water and household water off the slope Yes DRAINAGE DESIGN  (CHAPTER 6) A MoSSaiC project is likely to be effective in reducing landslide hazard in this community  Final drainage plan agreed upon 2 0 4    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T the community will appear to benefit directly 5. Construction of rip-rap to protect natural from large-scale interventions (e.g., construc- channels or gabion baskets to retain steep tion of main drains); others will see less con- sections of slope struction activity, even though they might still benefit from the overall reduction in surface Referring to the above example categories, water infiltration. The project rationale should table 5.10 illustrates how different drainage thus be reiterated: the intervention is designed interventions may be appropriate in different to improve drainage and reduce landslide haz- slope process zones for improving slope stabil- ard for the whole community and slope, ity. rather than for individual houses. 5.7.2 Draw an initial drainage plan It might be appropriate to consider several categories of intervention for a particular Go back into the community with the slope community. Be sure to describe these catego- process zone map and summary of potential ries clearly and simply, so they are readily dis- drainage measures and, in each zone, identify tinguishable from one another and easily possible locations for any new drains. Draw understood by community residents. Follow- these on a fresh plan of the community (fig- ing are some examples: ure  5.32) and take photographs of key loca- tions to enable easy identification of the drain- age routes or any potential problems. Be fully 1. Construction of contour (intercept) drains aware of safeguards regarding landownership, to capture surface water runoff compensation for trees or land, and any other 2. Construction of downslope drains to con- relevant issues. vey water off the slope Drawing potential drain locations on pho- tographs is especially useful in fostering dis- 3. Repair of existing drains cussion with community residents and in pre- 4. Installation of roof guttering and gray water sentations at community meetings. Figure 5.33 pipes to capture water from houses presents an annotated photo that should be FI G U R E 5. 32  Example of an initial drainage plan 0 12 0 10 80 ZONE E ZONE B ZONE D60 ZONE C ZONE A possible downslope drains LOWER SLOPE ZONE F possible intercept drains existing drains 60 slope process/drainage zones 100 previous landslides CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 0 5 linked to the initial community drainage plan F IG U R E 5 . 33  Proposed midslope intercept using GPS coordinates or descriptions of the drain alignment precise location. 5.7.3 Assign priorities to the different zones To assist in decision making and budgeting, each of the zones and interventions should be assigned a priority rank based on the relative landslide hazard and potential effectiveness of the proposed intervention. Table 5.11 illus- trates a helpful way of summarizing this infor- TA BLE 5 .1 0  Illustrative slope process zones and associated potential drainage measures FIELD OBSERVATION AND INTERPRETATION DESCRIPTION OF EFFECTIVE DRAINAGE ZONE OF SLOPE FEATURE MAP INTERVENTIONS (CATEGORIES 1–5) Planar slope topography with multiple cut Rationalization of household drainage network slopes and several associated minor slides to prevent convergence at cut slope locations A (1, 2, 3) Dense housing with incomplete or broken surface water drains Roof water capture (4). Highly convergent topography with previous Fixing road drain (3); interception of surface major landslide and deep accumulation of water runoff on upper slope area (1) debris; some houses rebuilt on debris Rationalization of household drainage network B Higher-density housing adjacent to debris— to prevent convergence at cut slope locations multiple cut slopes, incomplete or broken (1, 2, 3, 4) drains and retaining walls Significant surface runoff and seepage Small-scale convergent zones due to alteration Rationalization of household drainage and of topography and drainage by house chaotic drainage network to prevent conver- construction gence at cut slope locations (1, 2, 3) C Multiple small slides and tension cracks Roof water capture (4) Dense housing with incomplete drains and highly altered natural drainage pattern leading to convergence at multiple locations Steep planar topography with very shallow Drainage would not significantly improve soils/bedrock outcrops stability but could be implemented to reduce D flooding (1, 2) Significant surface runoff (including from road and roofs) but relative stability Small-scale convergent zones aggravated by Rationalization of household drainage and cut slopes and altered drainage chaotic drainage network to prevent conver- E Minor cut slope failures exacerbated by gence at cut slope locations (1, 2, 3) discharge of roof water into soil and poorly Roof water capture (4) designed drains Lower slope—deep soils saturated by Interception of surface water in upper slopes infiltration of water from upslope is likely to lower the water table in this zone Tension cracks indicate instability and hence improve stability; existing ravine F channel subject to erosion, flooding, siltation, and meandering—requires channelization and protection due to projected increased discharge from new drains (5) Note: See section 5.7.1 for descriptions of example drainage intervention categories 1–5 2 0 6    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T TAB L E 5.11  Illustrative prioritization of different drainage interventions in each of the zones ZONE CATEGORY OF INTERVENTION A B C D E F 1. Construct intercept drains to capture surface water runoff      2. Construct downslope drains to convey the water off the slope      3. Mend or repair existing drains and connections     4. Install roof guttering and gray water pipes to capture water from     houses 5. Construct rip-rap to protect channels or gabion baskets to retain  slopes Minor or no intervention needed  Priority High Very high High Low Medium Medium Note: See figure 5.21 and tables 5.6 and 5.10 for descriptions of the zones. mation as a matrix of zones, intervention nity, the implementing agency, and all stake- types, and priorities (this is derived from infor- holders. This vital part of the process should mation presented in figure 5.21 and tables 5.6 be conducted in the same manner as the previ- and 5.10). This priority matrix should be ous discussions. Because the map and the pro- clearly communicated to the community and posed intervention and priority matrix have to the rest of the task teams and the MCU in been developed with the involvement of all the context of the slope process zone map, ini- stakeholders, there should at this point be no tial drainage plan, and landslide hazard assess- surprises. Be sure to include a community ment process. walk-through during this phase of the discus- Additional benefits to the community sions so that details can be identified and the should be considered (such as potential for plan annotated or adjusted accordingly. reduced flooding, short-term employment, or Once all stakeholders have agreed on the improved environmental health). These bene- map and the intervention, the next stage is to fits may be deemed as, or more, important as formulate a detailed drainage design and to the potential reduction in landslide hazard. generate work packages; this is the subject of chapter 6. 5.7.4 Sign-off on the map and the proposed intervention MILESTONE 5: Organize a community meeting to discuss and Sign-off on prioritized zones and finalize the landslide hazard reduction and drainage prioritization plan with the commu- initial drainage plan CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 0 7 5.8 RESOURCES 5.8.1 Who does what CHAPTER TEAM RESPONSIBILITY ACTIONS AND HELPFUL HINTS SECTION Knowledge of community • Become familiar with the process used for community 5.3 engagement principles and engagement Funders and practices policy makers Coordinate with the MCU and government task teams • Review and determine the most suitable form of 5.3 Identify the best form of community participation community participation and • Identify community liaison experts; such individuals are mobilization (principles, practices, already likely to be part of the community task team, but and specialists) there may be other specialist colleagues or NGOs that can offer additional advice Coordinate with community MCU liaison task team Understand whether a MoSSaiC • Review a summary of the slope stability assessment 5.7 project is scientifically justified in • Review the slope process zone map and initial drainage a community plan Coordinate with landslide assessment and engineering task team Sign off on initial drainage plan • Identify key community residents to assist 5.3.2 Include key community members Helpful hint: Give time to residents who help in this way in mapping team at the start of a project. They can become strong advocates of MoSSaiC and help ensure positive uptake. • Take advice from the community as to where they would 5.3.3 Hold community meetings to like such meetings held and what venue is likely to attract mobilize community the greatest number of attendees Helpful hint: Repeat this several times. New information is 5.4 acquired on each visit perhaps from different residents, Undertake walk-through surveys and new drainage details are observed. Repeat visits build Government task trust and community ownership. teams Construct community slope • Construct the map on site so relevant details are 5.4.4 feature map captured Assess whether a MoSSaiC Helpful hint: Speak to relevant geotechnical colleagues in 5.3; 5.6 project is appropriate other agencies to assist as required. • Identify hillside zones requiring different surface water 5.7 Assign different surface water management approaches management approaches as appropriate Helpful hint: Communicate the zoning concept to residents to ensure expectations are correctly set. Coordinate with community task teams Community task Contribute local knowledge to • Become familiar with MoSSaiC approach and local 5.3.3 teams drainage hazard mapping context Coordinate with government task teams 2 0 8    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T 5.8.2 Chapter checklist SIGN- CHAPTER CHECK THAT: TEAM PERSON OFF SECTION 99Base map drawn 4.7 99Community representatives and community groups approached for an initial 5.3 discussion 99Plans made for a community meeting, and all stakeholders, elected officials, 5.3 and media invited; comments from the Q&A session recorded 99High percentage of residents visited during the community slope feature mapping process to gain as much local information as possible regarding 5.4 drainage and landslide issues 99Main drainage lines, topographic convergence, evidence of instability, and previous landslides identified and incorporated into a slope process zone map; 5.5 landslide hazard and role of surface water infiltration qualitatively assessed 99Quantitative or scientifically based methods applied to confirm landslide hazard and dominant slope mechanisms; surface water management identified as an 5.6 effective way to reduce landslide hazard in the different slope process zones 99Appropriate drainage measures identified and prioritized, and an initial 5.7 drainage plan drawn up 99Milestone 5: Sign-off on prioritized zones and initial drainage plan 5.7 99All necessary safeguards complied with 1.5.3; 2.3.2 5.8.3 References Arnstein, S. 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Washington, DC: World Geotechnics 31 (7): 529–36. Bank. 2 1 0    C H A P T E R 5 .   CO M M U N I T Y- B A S E D M A P P I N G F O R L A N D S L I D E H A Z A R D A S S E S S M E N T “During the past three decades policy statements by all major agencies have included risk reduction as a pre-condition and an integrated aspect of sustainable development… but when it comes to practical implementation, comparatively little has been done.” — C. Wamsler, “Mainstreaming Risk Reduction in Urban Planning and Housing: A Challenge for International Aid Organizations” (2006, 159) CHAPTER 6 Design and Good Practice for Slope Drainage 6.1 KEY CHAPTER ELEMENTS 6.1.1 Coverage This chapter discusses the delivery of MoSSaiC ground. The listed groups should read the indi- (Management of Slope Stability in Communi- cated chapter sections. ties) landslide risk reduction measures on the AUDIENCE CHAPTER F M G C LEARNING SECTION    Principles for general alignment of drains 6.3   Methods for estimating drain discharge and designing drain size 6.3    Drain functions and locations affecting detailed drain alignment 6.4   Drain construction specifications: materials and details 6.5   Approaches to capturing household water 6.6   Producing the final drainage plan and estimated cost 6.7 F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors 6.1.2 Documents CHAPTER DOCUMENT TO BE PRODUCED SECTION Proposed and final drainage plans 6.3–6.7 Table of cost estimates for drainage construction 6.7 213 6.1.3 Steps and outputs STEP OUTPUT 1. Identify the location and alignment of drains Proposed drainage • Use the slope process zone map and initial drainage plan as a starting point; apply plan (drain drainage alignment principles to identify potential drain network alignment alignments and dimensions) • Refine alignment details on site 2. Estimate drain discharge and dimensions • Calculate surface water runoff and household water discharge into proposed drains • Calculate required drain size 3. Specify drain construction and design details Full drain specification 4. Incorporate houses into the drainage plan List of quantities • Identify houses to receive roof guttering, gray water pipes, water tanks, and needed for hurricane straps household connections • Determine how household water will be directed to the drains (via pipes connected by concrete chambers or small drains) 5. Produce final drainage plan Final drainage plan • Include all drain alignment and household connection details on the plan and cost estimate • Estimate total project cost from unit costs 6. Stakeholder agreement on plan Sign-off on the • Meet with the community and refine the plan final drainage plan • Complete checks regarding relevant safeguards • Submit plan for formal approval 6.1.4 Community-based aspects and household water infiltration have been confirmed as the main contributors to land- This chapter takes the outputs of the commu- slide hazard. For such drainage interventions nity-based mapping process (slope process to be effective and stay within budget requires zone map and initial drainage plan) and devel- an understanding of the localized causes of the ops a detailed drainage plan for implementa- landslide hazard, and careful design and speci- tion in the community. Residents with knowl- fication of the works. Drainage should be edge of the community, hillslope layout, and designed to intercept and control surface local construction practices can contribute water flows generated by rainfall and domes- valuable information and ideas at this stage. tic water usage, thus reducing the infiltration The community agrees to the final drainage of water into the slope material and improving plan before sign-off by the MoSSaiC core unit slope stability. (MCU). The community-based mapping process and landslide hazard assessment described in chapter 5 provides the foundation for this 6.2 GETTING STARTED design process. Experienced engineers and technicians will need to refine or revise the ini- 6.2.1 Briefing note tial drainage alignments, estimate the volume of water likely to be entering the new drains, Drainage design for landslide hazard reduction define the required drain size and design for Improving surface water drainage can increase construction, identify household drainage slope stability in communities where rainfall measures, and estimate overall project cost. 2 1 4    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E The importance of good design • inform residents of good slope manage- ment and landslide hazard reduction prac- A good drainage design will achieve the fol- tices; lowing: • be the focal point of a holistic approach to • Interception of rainfall runoff from the landslide risk reduction for governments slope surface and roofs and international development agencies; and • Capture of gray water from houses • be included in broader poverty reduction, • Controlled flow of all intercepted/captured disaster risk reduction, and climate change surface water in a network of drains adaptation programs. • Reduced landslide hazard. 6.2.2 Guiding principles Good design will also minimize the need for The following guiding principles apply in land-take, the potential for drain obstruction slope drainage design: by debris, and ongoing maintenance. • Be as precise as possible in specifying drain- Even if the government has little experi- age alignment and design in terms of type, ence in designing and implementing drainage size, and materials. Conduct supplemen- works in vulnerable unauthorized communi- tary surveys of any complicated drainage ties, there are likely to be relevant local design lines within the community as necessary. and construction standards or specifications for drains. Entities such as nongovernmental • Apply relevant engineering and construc- organizations (NGOs), local contractors, and tion standards and protocols. community residents with construction skills • Be as precise and realistic as possible in the also may be able to identify examples of good initial estimate of quantities so the overall practices in drainage design. These sources of project budget can be estimated. information should be reviewed by the land- slide assessment and engineering task team, • Deliver a holistic presentation of the proj- and appropriate standards and specifications ect (plan and budget) for approval by the selected. Drain effectiveness in reducing land- MCU and the government agency in charge slide hazard depends on adhering to such of implementation. standards and specifications. Accurate specifi- • Ensure that all relevant safeguards are cation of these details also ensures accurate addressed, especially regarding drain align- estimates of the total project budget for deci- ment, with both landowners and commu- sion-making, financial, and management pur- nity residents. poses. The final drainage plan will need to meet appropriate standards, provide adequate 6.2.3 Risks and challenges construction specifications and cost estimates, Design for easy drain maintenance and be approved before work packages can be drawn up and contracts awarded. Although the importance of drain mainte- nance is widely recognized by funders, gov- Additional benefits ernments, and communities, it is rarely under- Besides reducing landslide hazard in a tar- taken. The need for cleaning and structural geted and cost-effective manner, a commu- maintenance should be explicitly factored into nity-based program of surface water manage- drainage design and on-site construction deci- ment can sions. Drains can, to some extent, be designed to be self-cleaning and therefore easier to • reduce localized flooding and soil erosion; maintain. In particular, shallow flow gradients • improve the community’s environment; should be avoided, and contour (intercept) CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 1 5 drains should be designed to keep flow veloci- and downpipes that should be connected ties generally high (to limit sediment deposi- directly to lined drains,or to properly covered tion). Areas of drain constriction, such as nar- containers for rainwater harvesting (with row culverts or abrupt changes in alignment, overflow pipes into drains). Gray water outlets should be avoided so debris does not accumu- (e.g., sinks and showers) should also be con- late and cause the drain to overflow. Well- nected to the drainage network if there is no designed drains that have been constructed other provision for household drainage. Soak- and finished to a good standard, kept clear of aways should be avoided if possible since they debris, and regularly inspected for damage act as a point water source by directly adding will afford a greater level of protection to com- water to the slope material. munities and have a longer design life than If there are no new drains adjacent to a poorly designed and constructed drains. house, connections can be made using readily available materials and appropriate technol- Prioritizing locations for drain construction to ogy, such as wide diameter plastic pipes con- reduce landslide hazard nected by a sequence of concrete chambers. Donors and governments cannot build drains MoSSaiC has also developed a type of drain for all houses in all communities. Even in the suitable for use in locations where a shallow vulnerable landslide-prone communities trench can be excavated in the soil. The trench selected for MoSSaiC projects, it is not possi- is lined with sturdy polythene sheeting (such ble from a budgetary or political standpoint to as sunlight-stable greenhouse polythene fund every drainage intervention that might be sheeting) held in place by a wire mesh. The beneficial. For each of these communities, the mesh is formed to the shape of the drain by slope process zone map, initial drainage plan, hand and secured with U-shaped pegs made and drainage prioritization matrix developed from steel reinforcing rods. These materials in chapter 5 should enable broad priorities to can be purchased for less than 10 percent the be established. Once the design and specifica- cost of similarly sized concrete drains; are tion of the drainage plan is complete, the cost much cheaper to transport and easy to carry; of these interventions can be estimated. Deci- and, apart from some short instruction in their sion makers should use this information— assembly, require no previous construction along with the relevant local safeguards and experience. protocols—to allocate the project budget in a In some high-priority zones of the commu- transparent and justifiable way. nity, these household-level drainage measures may be included as part of the project. Because Household rainwater and gray water it is not feasible or affordable to provide such management measures for every house, including examples In unauthorized communities and among the of these methods in the final drainage plan will wider public, there may be little awareness of encourage residents to adopt low-cost or other how simple, low-cost improvements in house- appropriate technology solutions on a self- hold drainage can reduce landslide hazard. Yet help basis. Such solutions offer certain techni- the adoption of such drainage and slope man- cal, political, and financial advantages, and agement practices can ensure the sustainabil- play a role in the overall improvement of sur- ity of MoSSaiC projects and be highly cost- face water management. effective. One means of encouraging adoption is to demonstrate simple household-scale sur- 6.2.4 Adapting the chapter blueprint to face water management practices that can be existing capacity used in conjunction with standard drain con- Use the matrix opposite to assess the capac- struction methods. ity of the MCU and the government task Throughout the project, residents should teams (or collaborating government agency) be made aware of the need for roof guttering to deliver a final drainage plan at a profes- 2 1 6    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E sional level in accordance with relevant engi- 6.3 PRINCIPLES AND TOOLS FOR neering design standards. This plan will GENERAL ALIGNMENT OF include a drainage design that affords best DRAINS possible landslide hazard reduction, com- plete with construction specifications and cost estimates for the development of work The initial drainage plan should already indi- packages. cate potential drain locations, identified on the basis of slope zone processes, dominant surface 1. Assign a capacity score from 1 to 3 (low to water issues, and possible types of surface water high) to reflect the existing capacity for management. The landslide assessment and each of the elements in the matrix’s left- engineering task team (assisted by an experi- hand column. enced engineer, if necessary) must develop this plan into a fully specified drainage design that 2. Identify the most common capacity score will capture as much surface water as possible, as an indicator of the overall capacity given budget and site constraints. level. This section provides guidance on princi- 3. Adapt the blueprint in this chapter in accor- ples for designing main drain alignments— dance with the overall capacity level (see intercept (contour) drains and downslope guide on next page). drains, methods for estimating the discharge of surface water runoff from specific slope sec- EXISTING CAPACITY CAPACITY ELEMENT 1 = LOW 2 = MODERATE 3 = HIGH Experience in designing No practical experience in Some experience with drain Sound experience in all drainage networks on slopes, designing surface water drains construction on slopes or aspects of designing drainage calculating slope surface water for slopes knowledge of drain design networks on slopes—engi- and drain capacity, applying calculations neering expertise and engineering design standards, understanding of slope and writing specifications for hydrology drain construction Experience in developing No experience in drawing site Experience in drawing site Experience in drawing site accurate and detailed site plans at large scale/high plans at large scale/high plans at large scale/high plans at a large scale and high resolution, or in incorporating resolution or in using resolution and in using GIS/ resolution, and in incorporat- other mapped data geographic information CAD software to incorporate ing other mapped data system/computer-assisted relevant mapped data (features such as drain design (GIS/CAD) software to alignment and design, paths, combine spatial data and and houses) into these plans produce maps Guidelines available on local No guidelines available, and Some guidelines and examples Comprehensive guidelines and drain design and construction few examples of good of good practices are available several examples of good standards and specifications practices practices are available Information on unit costs of No information or procedures Some information and Standard unit costs for construction, procedures for available, and limited procedures for quantity construction and quantity quantity estimation, and experience in estimating estimation, and some estimation procedures expertise in estimating community project costs experience in estimating available, and sound experi- community-based project community project costs ence in community-based costs available project cost estimation Project safeguards Documented safeguards need Documents exist for some Documented safeguards to be located; no previous safeguards available from all relevant experience in interpreting and agencies operating safeguard policies CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 1 7 CAPACITY LEVEL HOW TO ADAPT THE BLUEPRINT 1: Use this chapter The MCU needs to strengthen its capacity before developing a final drainage plan. This might involve the in depth and as a following: catalyst to secure • Hiring an experienced engineering technician from the commercial sector to estimate slope surface water support from flows and drain capacity other agencies as appropriate • Hiring an experienced geographic information system/computer-assisted design (GIS/CAD) technician to develop the final drainage plan • Developing standard drain design, construction, and cost estimation practices from those documented in this book and from drain designs available in similar countries • Seeking advice from donors, the private sector, or other sources on project cost estimation practices • Approaching all relevant agencies to acquire their safeguard documents and distill them into a coherent working document for designing construction projects in communities 2: Some elements The MCU has strength in some areas, but not all. Elements that are perceived to be Level 1 need to be of this chapter addressed as above. Elements that are Level 2 will need to be strengthened, such as the following: will reflect current • If there is no substantive experience in community-based projects and generation of relevant unit costs practice; read the (e.g., for double handling of materials), these could be acquired from similar projects undertaken by NGOs remaining or in other countries, and this book used as a guide elements in depth and use them to • If there is limited expertise in producing detailed site plans or using GIS/CAD, advice could be sought further strengthen from a commercial partner or relevant agency capacity • If relevant safeguard documents are available but not collated, the MCU should systematically integrate them into the implementation process 3: Use this chapter The MCU is likely to be able to proceed using existing proven capacity. It would be good practice nonethe- as a checklist less for the MCU to document relevant experience in developing drainage designs, estimating project costs, and applying related safeguards. tions (for example, above a proposed intercept • Channel slope. Ensure that each drain sec- drain) and gray water from houses, and calcu- tion has a sufficient channel slope (grade) lation of drain dimensions. in the planned direction of flow (i.e., avoid- The design of the drainage network and ing reverse flows), and that the elevation of drain alignments is an iterative process sum- the drainage network outflow is above that marized in figure 6.1. of the receiving water body. 6.3.1 Drainage alignment patterns and • Capacity. Ensure that each drain section principles has sufficient capacity for calculated dis- charges from surface water runoff, house- In identifying the overall drainage alignment hold gray water, and subsidiary connecting pattern, adhere to the following general prin- drains; and that the combined drainage net- ciples: work discharge into the receiving water • Capture. Ensure that as much surface body will not cause flooding downstream. water, roof water, and gray water are cap- The revised drainage alignment design tured by the drainage network as possi- should take into account actual on-site condi- ble. tions, including the following: • Connectivity. Ensure that each drain sec- • Conditions that may restrict drain con- tion connects with and discharges into struction or reduce drain effectiveness and another drain, and that the entire drainage functionality network discharges into an appropriate receiving water body (such as a river, reten- • Existing drains that may need to be tion basin, main drain, or the sea). repaired, replaced, or eliminated 2 1 8    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E FI G U R E 6 .1  Iterative design process for developing final drainage plan Effective drainage measures for COMMUNITY- Slope process zones reducing landslide hazard MAPPING AND LANDSLIDE   HAZARD ASSESSMENT Initial drainage plan and drainage zone priority matrix (CHAPTER 5)  Design alignment pattern for  Design detailed drain align- network (section 6.3)  ments (section 6.4)  Account for details on site: • Functionality of drain Calculate: • Existing drains • Surface water discharge • Footpaths DRAIN • Roof water discharge • Landslides ALIGNMENT AND • Piped water discharge DESIGN PROCESS (ITERATIVE;  SECTIONS 6.3, 6.4, 6.5) Calculate drain sizes for given drainage alignment Draw proposed drainage plan  Specify drain construction: materials and details (section 6.5)  Design household measures and connections to drains INCORPORATION based on prioritized roof water  Account for details on site OF HOUSEHOLD WATER INTO PLAN and piped water discharge  (SECTION 6.6) calculations  SIGN-OFF OF Draw final drainage plan and estimate project cost FINAL DRAINAGE PLAN   (SECTION 6.7) Community sign-off Decision maker sign-off • Existing footpaths with or without drains Idealized drain alignment • Proposed new footpaths to be included in An idealized surface water drainage network the project comprises regularly spaced intercept (con- tour) drains connecting with a downslope • Areas requiring additional protection such drain in a herringbone pattern (figure 6.2). as existing landslides or channels prone to Local conditions, such as slope topography undercutting and bank failure. and the existing layout of houses and paths, are likely to make such an idealized configura- More detailed alignment issues associated tion impractical. Use the following four exam- with different drain types are described in sec- ples of slope drainage patterns to help confirm, tion 6.4. adjust, or augment the initial drainage plan CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 1 9 F IG U R E 6 . 2  Idealized hillside drainage plan F IGUR E 6. 3  Generalized alignment for use showing intercept and downslope drains with top-of-slope intercept drains top of slope top of slope main intercept drain flow lines 3W radius stepped typical drainage channel pattern within community main drain baffle wall at toe of slope Note: Lines orthogonal to contours (flow lines) Note: Lines orthogonal to contours (flow lines) indicate likely surface and subsurface water flow indicate likely surface and subsurface water flow paths. paths. and ensure that drains are aligned for best pos- F IGUR E 6.4  Intercept drain built on a sible capture of surface water given the topog- slope with few restrictions to alignment raphy and on-site conditions. Linear drain alignment and easy access In locations where there is easy access to the hillside and few restrictions to drain align- ment, a configuration similar to that shown in figure 6.2 may be possible. This design can be augmented with an intercept drain running across the upper section of the slope. Fig- ure 6.3 shows such an alignment with a major top-of-slope intercept drain (figure 6.4), and a complementary herringbone drain alignment downslope. This configuration can be very downslope drain and together create an inter- effective in managing surface water on steep cept zone across the slope (figures 6.6 and 6.7). but otherwise accessible slopes. Currently inactive landslide sites Complex topography and difficult access In many unauthorized hillside communities, Vegetation, buildings, topography, landowner- there may be sites where landslides have ship issues, boundaries, and other restrictions occurred and that subsequently appear to have may prevent the alignment of a single uninter- stabilized. The community mapping process rupted intercept drain across the entire slope completed in chapter 5 should have identified (figure 6.5). such sites. In such cases, it may be appropriate to Even if there is no evidence of current design several separate drains along a particu- movement, there is no assurance that—given lar contour that each connect to a different reduced soil strength, post-landslide topogra- 2 2 0    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E FI G U R E 6 .5  Drain alignment complexities F IGUR E 6. 6  Network of small intercept drains intercepting surface water along entire uppermost contour of slope top of slope multiple intercept drains l nne a. Vegetation, a previously built footbath (with underdesigned slip drain) and topography cha restrict the alignment of a new intercept drain. r rive g stin exi F IGUR E 6.7  Downslope drain b. Undulating topography needs to be carefully surveyed, especially when aligning an intercept drain, so as to achieve self-cleaning gradients. phy, and associated subsurface flow patterns (such as soil pipes)—the landslide will not be reactivated by future rainfall events. It is thus important to align drains to minimize water inflow to these failed sites. The alignment shown in figure 6.8 can be used to good effect in such circumstances (figure 6.9). Currently active landslide sites (progressive failure) Some hillsides exhibit progressive failures— the continued, imperceptibly slow movement This drain is designed to receive water from the of material following a landslide-triggering main intercept drain, and a minor intercept event. Progressive failures are commonly asso- drain (center right) under construction. ciated with, but not restricted to, slope materi- als with high clay content. The community mapping process should since this can affect the alignment of main have identified sites of progressive slope fail- drains around the unstable area and may also ure and noted observations from residents require well-maintained minor drains to drain about periods of slope movement. Ascertain- the slide itself. Main drains should not be built ing that a landslide is still active is important, on or across progressive landslides or unstable CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 2 1 Figure 6.10 illustrates a drain alignment F IG U R E 6 . 8  Drain alignment to minimize designed to prevent water flow into the slide surface and immediate subsurface water flow area (to the left of the drain) from upslope, and into previously failed material drain the progressive slide material at the mid- top of slope point of the slide as well as immediately downslope. align drain to F IGUR E 6.10  Drain alignment for site of intercept surface progressive failure runoff above landslide main intercept top of slope drain landslide intercept drain to protect original drainage landslide zone route landslide zone Note: Lines orthogonal to contours indicate likely surface and subsurface water flow paths and minor drain to reduce emphasize the importance of the drain in preventing saturation of landslide increased pore water pressures within the landslide. zone main drain at toe of slope F IG U R E 6 .9  Drain aligned to intercept Note: Lines orthogonal to contours (flow lines) surface water and routed around a major indicate likely surface and subsurface water flow paths. A comparatively high-density drain network preexisting landslide can help prevent downslope water ingress to a failed site; consider aligning drains above, within, and immediately downslope of the failed material. 6.3.2 Calculating drain flow and drain dimensions Estimate the potential volumes of surface water runoff, roof water, and gray water that will be discharged into the new drains. Use local engineering protocols to select an appro- Crest of preexisting landslide is toward upper priate design rainfall intensity (i.e., with a center. specified probability or return period) to esti- mate surface water and roof water runoff. From these estimations, determine the material, since slope movement could cause required drain capacities and dimensions. cracking and leakage—potentially discharging This drain alignment-dimension design pro- drain water into the unstable material. How- cess is iterative and involves the steps ever, minor drains that start within the failed described in figure 6.11. mass and remove water from the area can be Methods that may be used to calculate the used to good effect. Low-cost drains made of discharge into drains, and hence the required flexible materials, such as those introduced in drain size, are summarized in the following sections 6.5.2 and 6.5.3, might be appropriate. sections; see table 6.1. 2 2 2    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E FI G U R E 6 .11  Iterative process for designing drain alignments and dimensions • Design alignment pattern for network • Design detailed drain alignments (sec- (section 6.3): tion 6.4) • Sketch possible drain locations using drainage  patterns and principles in section 6.3  • Account for details on site: • Functionality of drain—intercept or • Modify using detailed guidance in section 6.4 downslope or connecting; main drain or subsidiary drain  • Existing drains—main downslope drainage • Calculate: routes, drains that could be repaired and • Surface water discharge using the rational incorporated into the network method • Footpaths—with existing drains, or where • Roof water discharge from households by  new drains and paths can be built at the estimating roof area  same time • Gray water discharge from households using • Landslide areas that need protection from water company data surface water  • Calculate drain sizes for given drainage alignment using the Manning equation. • Revise and refine the alignment: • If the required intercept drain size is too large for the proposed alignment, look for another intercept drain location further upslope, or divide the network into smaller subcatchments, or consider increasing drain slope to increase discharge • If the required downslope drain size is too large for the proposed alignment, divide network into smaller subcatchments and increase the number of downslope drains • For any adjustments to the alignment, recalculate surface water and household discharge into the drain • After completing any required revisions, draw the proposed drainage map (section 6.4)  Specify drain construction: materials and details (section 6.5) 6.3.3 Estimating surface water discharge return period of 1 in 100 years) will be more expensive than designing small drains for The amount of water flowing over a slope sur- annual or high-frequency events. face during rainfall (surface water discharge) • Designing large drains for low-frequency, depends on the intensity and duration of rain- high-duration rainfall events may effi- fall, rate of infiltration into the soil, slope ciently remove surface water from a hillside steepness, and surface cover. The capacity of a community but cause flooding downstream drainage network should be designed to unless the drain flow velocity is reduced or accommodate surface water discharge cap- water is stored. tured by intercept drains for a specified rain- fall event. The optimal design rainfall return • The money spent in constructing a high- period should be chosen based on local engi- capacity drain might be otherwise spent on neering standards and expert engineering building a number of smaller drains (WHO judgment on the following issues, among oth- 1991). ers: Surface water discharge can be estimated • Designing large drains for a low-frequency, using the rational method; a simple approxi- high-intensity rainfall event (e.g., with a mation widely used for calculating peak dis- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 2 3 TA BLE 6 .1  Calculations for estimating discharge into drains and drain size CHAPTER CALCULATION PURPOSE IMPLEMENTATION SECTION Surface water Calculation of surface water See the online calculator for the runoff runoff discharged (m3/s) from rational method, http://www. 6.3.3 specific area of the slope for lmnoeng.com/Hydrology/ specific rainfall event rational.htm Roof water Calculation of percentage of rainfall intercepted by roofs; used to estimate the effectiveness of 6.3.4 roof guttering for removing water from the slope and the discharge Calculation can be developed as a entering drains simple spreadsheet model using equations to account for housing Piped water supply Calculation of piped water density, roof area, average piped supplied to houses and dis- water supply to houses, and charged to slope; used to rainfall intensity estimate effectiveness of 6.3.4 household drains for removing gray water from the slope and the discharge entering drains Drain size Calculation of the required Online calculators for prismatic cross-sectional area for a drain to channels are at http://onlinecalc. accommodate a specific sdsu.edu/onlinechannel15.php 6.3.5 discharge on a given slope and http://www.calculatoredge. gradient com/new/manning.htm#velocity charge in small urban drainage areas (<  80 Where: hectares). The method uses a runoff coeffi- Q = Peak flow (cf/s or m3/s) cient to account for the difference between k = Conversion factor (1.008 for imperial or rainfall and the resulting surface water runoff 0.00278 for metric) due to variations in land use (table 6.2), which C = Runoff coefficient (see table 6.2) is a proxy for a number of processes including i = Rainfall intensity (in/h or mm/h) infiltration, temporary storage, and other A = Upslope contributing drainage area losses (see Premchitt, Lam, and Shen 1986 for (acres or hectares) evidence of surface cover effects on slope dis- charge). Because these processes are not Estimate the potential surface water dis- explicitly accounted for, the rational method charge from areas of the slope above proposed (equation 6.1) does not allow calculation of the intercept drains to determine the required timing of peak discharge (also known as the capacities of intercept and downslope drains. time of concentration). It also assumes con- Perform the following steps to apply the ratio- stant rainfall intensity across the drainage area nal method: and over time. These simplifying assumptions Step 1: Contributing area (A) do not significantly affect discharge estima- tions for small, steeply sloping drainage areas • Calculate the area of the slope that will dis- with no flood storage; but for larger catchment charge surface water runoff into the pro- areas (> 80 hectares), engineers should use posed intercept drain (the contributing area). other calculation methods. • Use a contour map to estimate the bound- aries of the contributing area. Assuming Q = k C i A (6.1) 2 2 4    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E TAB L E 6.2  Values of runoff coefficient C for the rational method LAND USE C LAND USE C Business: Lawns: Downtown areas 0.70–0.95 Sandy soil, flat, 2% 0.05–0.10 Neighborhood areas 0.50–0.70 Sandy soil, average, 2–7% 0.10–0.15 Sandy soil, steep, 7% 0.15–0.20 Heavy soil, flat, 2% 0.13–0.17 Heavy soil, average, 2–7% 0.18–0.22 Heavy soil, steep, 7% 0.25–0.35 Residential: Agricultural land: Single-family areas 0.30–0.50 Bare packed soil Multi units, detached 0.40–0.60 Smooth 0.30–0.60 Multi units, attached 0.60–0.75 Rough 0.20–0.50 Suburban 0.25–0.40 Cultivated rows Heavy soil, no crop 0.30–0.60 Heavy soil, with crop 0.20–0.50 Sandy soil, no crop 0.20–0.40 Sandy soil, with crop 0.10–0.25 Pasture Heavy soil 0.15–0.45 Sandy soil 0.05–0.25 Woodlands 0.05–0.25 Industrial: Streets: Light areas 0.50–0.80 Asphaltic 0.70–0.95 Heavy areas 0.60–0.90 Concrete 0.80–0.95 Brick 0.70–0.85 Parks, cemeteries 0.10–0.25 Unimproved areas 0.10–0.30 Playgrounds 0.20–0.35 Drives and walks 0.75–0.85 Railroad yard areas 0.20–0.40 Roofs 0.75–0.95 Source: http://water.me.vccs.edu/courses/CIV246/table2.htm. Note: The designer must use judgment to select the appropriate coefficient value within the range. Generally, larger areas with permeable soils, flat slopes, and dense vegetation should have the lowest coefficient values. Smaller areas with dense soils, moderate to steep slopes, and sparse vegetation should be assigned the highest coefficient values. surface water will run over the slope at Step 2: Rainfall intensity (i) 90  degrees to contours, sketch flow lines • Use past rainfall records to identify the on the map to identify the area of slope intensity, duration, and frequency of differ- above the drain that will contribute sur- ent rainfall events. face water runoff. • Select the maximum rainfall intensity for • Conduct a site visit to verify the boundaries which the drains are to be designed. of the contributing area. Step 3: Runoff coefficient (C) • If calculating discharge from house roofs separately, be sure to subtract the roof area • Select a runoff coefficient from table 6.2 from the slope area so as not to double that best represents the contributing area count roof water (see section 6.3.4). land use. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 2 5 • If there is more than one distinct type of Step 1: Proportion of rainfall intercepted by land use, subdivide the area accordingly roofs and assign appropriate values of C to each • Calculate the total contributing area of the subarea. slope that will discharge water into the pro- • If the area has been subdivided according to posed drain. different values of C, recalculate A for each • Estimate the area of the slope covered by area. Multiply A and C for each subarea, houses by using geographic information add the results together, and divide by the system/computer-assisted design (GIS/ total area to obtain a weighted value of C for CAD) to directly measure the building foot- the entire contributing area. prints, or estimating the average house size Step 4: Peak discharge (Q) and multiplying this by the number of houses on the slope. Use the rational method to calculate peak sur- • Divide the total house footprint area by the face water discharge from the contributing slope area to obtain the proportion of the area. slope over which houses directly intercept 6.3.4 Estimating the discharge from rainfall on their roofs. houses • Multiply the result by the rainfall for the Each household can affect the amount of chosen design event (see section 6.3.3) to surface water on a slope in two ways: (1) by calculate the potential maximum roof intercepting rainfall on roofs and either dis- water capture and subsequent discharge charging it directly onto the slope, collecting into drains. it, or directing it into drains; and (2) by dis- • Be careful not to double count the roof charging gray water and septic waste onto water contribution in estimating surface the slope. water discharge (section 6.3.3). If the housing density is high, the propor- tion of rainfall intercepted by roofs will be cor- Step 2: Water supply respondingly high. If there is piped water sup- • Obtain water company data on average sup- ply, this can result in a significant increase in ply per household over a specific time surface water discharge—in some cases, period. amounting to as much as that generated by rainfall. • Multiply the average supply by the number If the project scope includes installing roof of households in the community to obtain guttering, gray water pipes, and connections to the total amount of water supplied to the the new drains, the resulting discharge should slope for that period. be accounted for in drain capacity calcula- • Convert from volume to equivalent depth tions. The importance of household water (e.g., mm/day), and compare with the aver- capture also needs to be established both as age rainfall rate for the equivalent time part of the justification for the intervention period to determine the significance of piped and as a way of changing slope management water supply in adding water to the slope. perceptions and practices. Use the following steps to estimate house- • Estimate how much water is lost from pipes hold water contributions to surface water. through leakage and how much will be This method can be applied to the whole com- added to the slope as septic waste. (The munity to estimate an average discharge for water company should be able to provide the area or specific contributing area dis- an estimate of these figures.) The remain- charges into different drains. ing supply represents the maximum vol- 2 2 6    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E ume that could be captured from houses as sequence of calculations can be entered into a gray water and discharged into the drains. spreadsheet to allow multiple iterations to be carried out until the correct drain size is iden- 6.3.5 Estimating dimensions for main tified. A typical sequence of steps using an drains online calculator is as follows. Use the predicted surface water discharge Step 1: Define an initial trial drain size and and, if relevant, the estimated household water channel slope discharge to determine appropriate dimen- sions (cross-sectional areas) for the main • Select a channel width and flow depth and intercept and downslope drains. Typically, the assume a vertical side slope for a typical dimensions of the smaller subsidiary or house- open box drain. hold drains can be determined by rule of • Define the channel slope based on the pro- thumb, experience, or local knowledge. How- posed drain alignment identified in the ever, if drain size calculations are needed in field (channel slope = vertical channel rise/ order to conform with local engineering horizontal channel run). design standards or building codes, then these protocols should be followed. Step 2: Select a value for Manning’s constant (n) The Manning equation (6.2) is a semi- empirical equation that is the most commonly Typical values of finished and unfinished con- used to calculate uniform steady-state flow of crete channels are 0.012 and 0.014, respectively. water in open channels. Step 3: Use an online calculator to determine the maximum drain discharge V = (k/n) × R2/3 × S1/2 (6.2) • Enter the values from Steps 1 and 2 into an Where: online calculator. V = Velocity (ft/s or m/s) • Calculate maximum drain discharge Q. k = Constant (1.485 for imperial units, or 1.0 for metric) Step 4: Identify the required drain size R = Hydraulic radius (ft or m) • Compare the maximum drain discharge S = Channel slope (ft/ft or m/m) with the estimated discharge from slope n = Manning’s constant defined for different surface runoff and from households (sec- channel materials tions 6.3.3 and 6.3.4) and the flow entering from any other drains. Drain discharge can be calculated using equation (6.3), in which flow velocity is esti- • Repeat the process with different realistic mated by the Manning equation (6.2). drain sizes and gradients until the required discharge can be accommodated by the Q = A × V (6.3) drain. Where: 6.3.6 Example to demonstrate intercept Q = Discharge (ft3s−1 or m3s−1) drain effectiveness A = Channel cross-sectional area (ft2 or m2) In this example, the rational method was used V = Flow velocity (ft s−1 or m s−1) to calculate surface water discharge upslope of a proposed intercept drain location. The drain This calculation can be applied iteratively was subsequently constructed (figure 6.12a). to identify the drain cross-sectional area Several households adjacent to the drain then required to accommodate a specified dis- connected their downpipes and gray water to charge. A number of online calculators are the drain. During a storm event, a resident noted available for this calculation. Alternatively, the the flow depth in the drain and observed the CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 2 7 flow velocity (figure 6.12b). These observations Step 2: Estimate the total drain discharge enabled estimations to be made of the total drain • Flow depth of 5 cm was observed in a 30 cm discharge for the 12-hour storm and of the actual wide section of the intercept drain with a proportion of rainfall captured by the drain. drain slope angle of approximately Step 1: Calculate the total rainfall delivered to 4 degrees and Manning’s n of 0.018 (unfin- the slope ished concrete with minor debris) • Total rainfall was 84 mm over 12 hours on • Using the Manning equation, estimate flow an area of 20,000 m2. velocity and discharge: V = 1.646 m/s, and Q = 0.024 m3/s (24 L/s) • Determine the rainfall delivered to the slope (before runoff ): • Assuming constant rainfall, the total drain discharge for the 12-hour storm is approxi- Q = 0.084 m × 20,000 m2 mately 1,036,800 L. Q = 1,680 m3 (1,680,000 L) Step 3: Compare total drain discharge to total rainfall F IG U R E 6 .1 2  Estimating observed drain flows The percentage of actual rainfall estimated to be captured by the drain is approximately (1,036,800/1,680,000) × 100 = 62 percent. Step 4: Estimate surface water runoff from the slope using the rational method • Apply the rational method using an average rainfall intensity of 7 mm/h (84 mm over 12 hours), a slope area of 20,000 m2, and a run- off coefficient of 0.6. • Assuming constant rainfall intensity, the steady-state surface water discharge from the slope is estimated to be 0.023352 m3/s, and the estimated total surface runoff is 1,008,806 L in 12 hours. • The percentage of rainfall estimated by the a. Main downslope drain conveys flow from an rational method to be converted into sur- intercept drain. face water runoff is (1,008,806/1,680,000) × 100 = 60 percent. This calculation allows two conclusions to be drawn: that the intercept drain is effective (capturing approximately 62 percent of total rainfall, Step 3), and that the rational method closely predicts the observed drain flow (com- paring the results of Steps 2 and 4). 6.3.7 Example to demonstrate the impact of drain channel slope on flow capacity b. Resident indicates maximum flow depth reached during a previous day’s storm. Steeper channel slopes increase the flow con- veyance of drains. Without proper design, 2 2 8    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E drains with steep channel slopes are often overbuilt—too large for likely flow rates—and F IGUR E 6.13  Impact of drain gradient on flow velocity and discharge construction materials are wasted. The impact of drain channel slope on flow 25 4.5 velocity and discharge is accounted for in the 4.0 Manning equation. The following example 20 3.5 flow velocity (m/s) assumes a concrete drain with an internal discharge (m3/s) 3.0 dimension of 45 cm wide by 40 cm deep and 15 2.5 Manning’s n of 0.012. Figure 6.13 shows that 2.0 for a 5 degree drain channel slope (typical of 10 1.5 an intercept drain running across a slope), the 5 1.0 maximum drain flow velocity is 6.78 m/s for a 0.5 maximum discharge of 1.24 m3/s. On a slope of 45 degrees, a downslope drain of the same 0 0 0 10 20 30 40 50 dimensions has much greater maximum flow drain gradient (degrees) velocity: 22.89 m/s and a maximum discharge of 4.12 m3/s—more than three times that of the same size intercept drain. The calculated flow Drain channel Drain discharge slopeDrain discharge capacity compared velocities and drain discharges for each drain Velocity capacity to 5° drain channel channel slope plotted in figure  6.13 appear Degrees Gradient (m/s) (m3/s) slope (%) below the figure. 5 0.09 6.78 1.24 100 10 0.18 9.71 1.75 141 6.3.8 Example to demonstrate the impact 20 0.36 13.73 2.47 199 of household water 30 0.58 17.43 3.14 253 40 0.84 20.98 3.78 305 The potential impact of household water (and 45 1.00 22.89 4.12 332 hence the effectiveness of comprehensive household water management) can be demon- strated using the example of a typical Eastern Caribbean hillside community with the fol- be reduced by approximately 45 percent. This lowing characteristics: example is illustrated in figure 6.14. Figure 6.15 shows the impact of publicly • Slope area = 7,000 m2 supplied piped water on the amount of surface • Average house footprint = 60 m2 water added to the slope as the number of houses grows. As housing density increases, so • Housing density = 30 percent of slope sur- does the effectiveness of roof guttering as a face means of reducing surface water—the larger • Annual average rainfall = 1,868 mm the roof area, the greater the percentage of rainfall intercepted. • Daily average piped water consumption per house = 450 L Calculating the total water supplied to the 6.4 DRAIN TYPES AND DETAILED slope shows that the publicly supplied piped ALIGNMENTS water effectively adds the equivalent of another 40 percent of annual average rainfall. Once the general alignment and provisional However, if all the rainfall intercepted by roofs dimensions of the main drains have been is captured, this reduces the effective rainfall determined, the next task is to confirm the volume by 30 percent; if, in addition to captur- exact alignment of each drain on site, taking ing roof water, 50 percent of household waste into account different drain types and func- water is captured, the total surface water can tions. In addition to the overall distinction CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 2 9 often involve several of the detailed alignment F IG U R E 6 .1 4  Effect of household water issues described in this section. Finally, in drainage in a typical community designing the detailed drain alignment, wider, 3,000 accessible drain sections may need to be incor- porated to allow for the installation of debris surface water added to slope with 30% housing density (mm per year) 2,500 traps. The following questions apply to the align- 2,000 ment of all types of drains: 1,500 • Is there enough space between houses, paths, and other structures or obstacles to 1,000 safely build a drain with adequate capacity? • Can the ground be excavated to a sufficient 500 depth or constructed in such a way that the 0 top of the drain walls will be flush with the no household 100% roof water slope surface, thus allowing surface water drainage and 50% piped runoff to enter the drain? If this is not pos- water capture sible, the drain may cause flooding and total piped water added to slope slope instability by blocking or concentrat- ing surface water flows. total rainfall added to slope • Does the proposed alignment have smooth Note: See text for values of input parameters. bends, or will structures or obstacles mean that the drain alignment has abrupt changes in direction? Sharp bends can result in tur- between intercept and downslope drains, this bulent flow, accumulation of debris, or section considers detailed alignment issues overtopping during high flows. associated with drains beside footpaths, exist- ing drainage lines that might require repair, • Does the drain alignment capture signifi- and drains across or above landslides. Drains cant sources of water from surface runoff connecting households to the main drains will and from tributary drains? F IG U R E 6 .1 5  Potential effectiveness of household drainage measures 4,000 surface water added to slope 3,500 3,000 2,500 (mm/year) 2,000 1,500 1,000 500 0 0 10 20 30 40 50 60 70 housing density (as percentage of slope area) total rainfall and piped water added to slope 100% roof water and 50% piped water capture Note: See text for values of surface water inputs. 2 3 0    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E • Does the drain alignment allow households to easily connect roof water and gray water F IGUR E 6.17  Main cross-slope intercept to the drain? drain constructed on a 35 degree slope angle • Are all the proposed drains connected so as to discharge the water safely off the slope without causing flooding or instability problems elsewhere? • Can large drainage areas be divided into subcatchments with separate drainage net- works to avoid the need for very large or very deep drainage channels? • Would the proposed alignments pose any significant construction or access chal- lenges, such as transport of materials to site, access for excavation and disposal of debris, or close proximity to houses? • Have the community, landowners, or indi- vidual households raised objections to drains being constructed in certain loca- tions? Safeguards are very important; ensure that all stakeholders understand and of topographic convergence and landslide agree to the drain alignment (figure 6.16). hazard. More generally, intercept drains can be used to capture surface water before it infil- trates soils in the upslope areas; this water FI G U R E 6 .16  Drain alignment must be correctly specified in communities could otherwise contribute to shallow subsur- face groundwater flows, serving to increase soil water pore pressures downslope. Ideally, two or more levels of surface water intercep- tion should be considered across the whole slope so that as many houses as possible are protected from uncontrolled surface water flows. In aligning intercept drains, ask the follow- ing questions: • Has the community mapping process iden- Getting the approval of residents and other tified zones of drainage convergence, stakeholders is especially important for detailed drain alignment when, as in this case, increased landslide hazard, or high housing the alignment passes close to houses and may density that could be protected by an inter- also cross informal pathways used by residents. cept drain? • Are there zones of exposed bedrock and high surface runoff above these conver- 6.4.1 Intercept drains gence or landslide zones? Aligning inter- Intercept, or contour, drains can play a major cept drains along the interface between role in reducing landslide risk (figure  6.17). exposed bedrock (upslope) and soil They can be very effective in preventing sur- (downslope) can be a very effective way of face water from upper slopes reaching zones maximizing surface water capture as long CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 3 1 as the upslope drain sidewall is flush with the slope surface to allow runoff to enter F IGUR E 6.18  Poor practice: Downslope drain construction begun at top of hillside the drain. rather than base of slope • Is there potential for two or more levels of intercept drains across the hillside? • Is there a proposed downslope drain or existing drainage channel of sufficient capacity to which to connect the intercept drains? If not, the concentrated flow of water from the intercept drain could cause problems elsewhere. • Will the proposed alignment of an intercept drain provide a sufficient channel gradient Beginning construction at the bottom of the and associated flow velocity and discharge slope and working upslope prevents concentra- tion of flow and erosion at unconstructed capacity? On steep, highly vegetated slopes, sections, as is starting to occur here. it can often be difficult to establish a line of sight or identify minor topographic features that will affect the channel slope of a pro- 6.4.3 Footpath drains posed intercept drain; it may be necessary Providing access to and within vulnerable com- to clear undergrowth and survey the pro- munities is often a priority for poverty reduc- posed drain alignment. tion and community development projects. 6.4.2 Downslope drains Quite frequently, however, the focus is restricted to building footpaths or steps without consider- Properly aligned downslope drains can take ing drainage provision, which should be an advantage of existing natural channels or sur- integral part of good footpath or road design. face flow paths that are active during heavy Existing or planned footpaths should be rainfall. Capitalizing on natural channels and incorporated into the overall community flow paths also enables the capture of tribu- drainage network for several reasons, includ- tary inflows that drain other areas of the slope. ing the following: Thus, a single downslope drain may have a • Paths, tracks, and roads can act as preferen- large catchment area and convey significant tial flow paths for surface runoff and can discharges (figure 6.18). generate concentrated flows of water dur- In aligning downslope drains, ask the fol- ing heavy rain. lowing questions: • Conversely, footpaths may have developed • Can major downslope drains be aligned on along minor natural drainage routes where the hillside to take advantage of existing community members have adopted these natural channel flows? convenient, less-vegetated routes for access. • Would such an alignment capture signifi- • Footpaths may follow a similar pattern to cant inflows from tributary drainage paths the idealized drainage pattern, with routes (including proposed new intercept drains), across the slope (along contours) and down and can these be clearly identified? the slope. • Can the proposed alignment help in manag- • The construction of a drain along an exist- ing water affecting zones of higher land- ing path may be relatively straightforward slide hazard (such as saturated areas and in terms of landownership issues and in areas of known instability)? getting construction materials to the site. 2 32    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E It is best to construct footpaths, footpath • Provision for culverts where drains need to drains, and culverts simultaneously, as this connect across footpaths. enables surface water capture to be holistically designed (figure  6.19). The decoupling of In aligning footpath drains, ask the follow- access provision from surface drainage design ing questions: is not uncommon, perhaps partly because • Are there existing drains along footpaths drainage and access are typically provided by that could be used or improved as part of different development projects or agencies. If the overall drainage network? there is provision for footpath construction in conjunction with the MoSSaiC project, two —— Do they have sufficient capacity, or are drain alignment and design issues should be they prone to blocking or overflowing? incorporated at this stage: Particularly note discharge capacities adjacent to steps and through culverts. • Provision for widening and stepping down the drain at the base of a long run of foot- —— Does the camber on the path direct path steps to reduce flow velocity water into the drain? If not, can a small upstand be constructed along the side of the path to redirect the water across the path into the existing drain? FI G U R E 6 .19  Examples of footpath and —— Can the drain be connected to the wider footpath drains being constructed drainage network? simultaneously —— Is there any evidence that the commu- nity can keep such drains clean on a reg- ular basis? Footpath drains can easily become blocked with vegetation debris, garbage, soil, and stones. • Are there footpaths that require better drainage? —— Is there enough space to build a drain? —— Can proposed footpath drains be linked to existing or proposed main drains? 6.4.4 Incomplete existing drainage In vulnerable communities, there may be existing drains that are incomplete, uncon- nected, broken, or blocked (figure  6.20). In some cases, these drains may be contributing to landslide hazard or flooding problems by discharging water onto unstable/marginally stable slope zones. The most likely such cir- cumstance is where a footpath or access inter- vention has previously been completed with- out an accompanying comprehensive drainage plan. The community slope feature mapping process should have identified such issues. At this stage, revisit the existing drains to determine if they can be repaired, extended, CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 33 F IG U R E 6 . 2 0  Incomplete and damaged drains a. Poor design: a newly constructed drain has no b. Old drain construction with no downslope planned outflow discharge management. The management of the discharge. discharge can serve to increase landslide risk. and connected to the proposed new drains. If unstable because of oversteepening of the this is not possible, the flow entering these old slope at the crest of the slide, and house foun- drains should be captured upslope and dations may be undermined. Houses on or diverted into the proposed drainage network. below the unstable area may be affected by In this regard, ask the following questions: progressive ground movement and subsid- ence, or endangered by further slope failure. • Are there locations where incomplete If water is contributing to the ongoing drains discharge onto the slope rather than connect to existing drains? movement or potential reactivation of land- slides in these areas, it may be possible to • Are there locations where existing improve the stability of the slope using appro- downslope drains discharge into broken priate drainage (figure 6.21). In determining drainage structures? whether to install a drain above a landslide to stabilize the slope, ask the following questions: By channeling water to a specific slope location, both of these conditions can increase • Examine how the water flow is channeled slope instability. They should be directly above the unstable area—does it flow onto addressed as part of the intervention. the failed material, and does it have a clearly defined channel? 6.4.5 Drains above landslides to stabilize the slope • Could the water be captured above the exist- ing failed material and channeled across and Areas of existing slope instability can be diffi- down the slope away from the area? cult to stabilize in certain cases and may con- tinue to threaten surrounding houses. Areas • Is there stable material above the failed above the active landslide zone can become zone that would allow drain construction? 2 3 4    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E organic material such as leaves and wood) at FI G U R E 6 .2 1  Drain construction above a key locations in the drain to prevent blockages. failed slope Typical locations for debris traps include points where debris is deposited due to reduced flow velocities (such as changes from steep to shallow channel slopes), or immedi- ately upstream of culverts. At debris trap locations, the drain design should include the following: • Easy access to the debris trap from a path or road to allow removal of debris • Widening of the drain section to accommo- Careful alignment can significantly reduce water flowing to potentially unstable hillside date the accumulation of debris without areas. causing the drain to overflow. Debris traps of varying designs are used 6.4.6 Incorporating debris traps into around the world. On steep hillsides in Hong drain alignment Kong SAR, China, for example, there are typi- cally two styles of trap at the point the drain Drains are likely to become blocked with enters a culvert. Figure 6.23 shows an example debris unless they are appropriately designed where consideration has been given both to and subsequently kept clean and well main- trapping debris and to ease of access for debris tained (figure 6.22). In heavy rainfall, a blocked removal. drain can overflow and contribute to landslide Good debris trap design must be accompa- hazard or flood houses. Debris traps are nied by a realistic plan for drain maintenance designed to collect debris (stones, garbage, and that identifies both government and commu- FI G U R E 6 .2 2 Postconstruction F IGUR E 6. 2 3  Debris trap in an urban area maintenance: Keeping drains free of debris of Hong Kong, SAR, China CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 3 5 nity responsibilities. A particular issue is gov- 6.5 DRAIN CONSTRUCTION ernment provision of solid waste collection SPECIFICATIONS: MATERIALS from communities, since debris removed AND DETAILS from drains and traps must be properly dis- posed of. The drainage work extent and construction Too often, low-income communities are specifications will be determined by the expected to maintain their drainage systems required capacity and function of each drain with minimal assistance, either as a result of section, and constrained by project budget and wishful thinking on the part of municipal on-site conditions. Options for drain design authorities or by default, because the munici- pality simply does not have the resources or and construction specifications should be capacity to maintain the system it has explained to all stakeholders to help establish installed. Rather, what the community needs reasonable expectations and avoid the need is support to enable it to carry out its part of for major revisions of the drainage plan. the work more effectively (WHO 1991, 53). Factors affecting drain construction speci- fication include the following: In considering the use and placement of • Drain size and alignment. The size, shape, debris traps, ask the following questions: and channel slope should be designed to • Are there locations in the proposed drain- give the required discharge capacity, and age alignments, or along existing drains, take into account space available for drain that will be vulnerable to blockage by construction and the effect of flow velocity. debris? Steep smooth channels with small cross- sectional areas and high flow velocities are • Is there enough space to widen the drain at likely to be self-cleaning (i.e., limit the these locations to accommodate a debris deposition of debris), but may be suscepti- trap? ble to channel erosion and increase flood- • Are these locations easy to access for clean- ing downstream. Conversely, low-gradient ing and removing debris from the commu- wide channels can cause debris to accumu- nity? late at low flows. • Is there a realistic plan for regularly clean- • Drain function and features. Intercept ing and maintaining debris traps? drains will have slightly different features (such as weep holes and lower channel 6.4.7 Proposed drainage plan slopes) than downslope drains, which Develop the first version of the final drainage might need to include steps to reduce flow plan, showing the alignments of all main velocities on steep sections, and baffle walls intercept and downslope drains, plus smaller to prevent overtopping. drains (along footpaths and connecting households). Use the on-site knowledge • Maintenance and safety issues. Open gained from developing the community slope drains with regular debris traps are gener- feature map, the slope process zone map, and ally easy to inspect for damage and to keep the initial drainage plan (chapter 5 and fig- clean and free of mosquitoes. Closed drains ure 6.24), and take into account the drainage may seem more aesthetically pleasing and alignment principles outlined in this chapter. take less space, but are more easily blocked, Figure 6.25 illustrates the draft final drainage are difficult to maintain, and capture less plan based on figure 6.24. Table 6.3 summa- surface runoff. Covered sections should be rizes some of the key issues to account for in restricted to culverts and locations where this final plan. safe access across the drain is required. 2 3 6    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E FI G U R E 6 .24  Example of an initial drainage plan 0 12 0 10 80 ZONE E ZONE B ZONE D60 ZONE C ZONE A possible downslope drains LOWER SLOPE ZONE F possible intercept drains existing drains 60 slope process/drainage zones 100 previous landslides FI G U R E 6 .2 5  Example of a draft final drainage plan 120 N 0 10 approx 50m 80 32 66 63 64 65 33 60 35 67 30 39 34 62 60 61 31 36 68 29 27 38 37 69 40 59 28 44 58 70 25 26 41 43 24 54 42 45 57 56 23 46 55 47 53 22 49 51 52 48 50 21 20 1 19 16 15 2 17 3 18 10 12 14 existing drains 7 8 13 4 6 9 11 60 proposed new drains 5 or existing drainage 100 lines needing repair • Construction material. For MoSSaiC proj- section 6.5.1) or robust polythene sheeting ects, the purpose of surface water drains is (for small low-flow drains, section 6.5.2). to reduce surface water infiltration into slopes—thus, all drains should be lined and To optimize the project budget, it may be made watertight (with weep holes where appropriate to include low-cost construction necessary) using concrete (for main drains, methods in some locations; other elements of CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 37 TAB L E 6. 3  Drainage alignment summary for use in developing final drainage plan LOOK FOR SIGNIFICANCE ACTION: DRAINAGE ALIGNMENT DESIGN Zones of topographic Topographic convergence concentrates Plan an intercept drain above such zones and connect to convergence water downslope and can cause slope a downslope main drain away from the area to an instability appropriate receiving water body. Zones of former slope Such zones imply the potential for future Plan to capture water above such zones and route drains instability instability or ongoing progressive (slow- around unstable material. moving) failures. Natural drainage These channels may have a large enough Map and incorporate these channels or drains into the channels or existing capacity to remove water discharged from plan if discharge capacity is sufficient. More than one downslope drains new drains downslope drain may be required in order to serve the whole community. Plan the spacing of downslope drains such that houses and intercept drains can be connected. Existing footpath Footpath drains can often intercept and Map and incorporate these drains into the plan if drains convey significant surface water discharges discharge capacity is sufficient. Make adequate provision and may be in close proximity to houses for any culverts needed to cross footpaths, as these can (making household water connections restrict flow and are often liable to blockage and severe easy) flow capacity reductions. Unconnected or Sections of drain that discharge concen- If these drains present a hazard, divert flows to other damaged drains trated, uncontrolled flows onto the slope drains or incorporate into the new drainage network can cause flooding, erosion, and landslide (indicating sections for repair). hazards Potential routes for Intercept drains are a critical element in Examine the hillside holistically—design a drainage intercept drain capturing upslope water and preventing pattern that best utilizes surface water interception water flow into topographic convergence routes. Note that the effect of a single cross-slope zones intercept drain can be achieved with several shorter intercept drains (see section 6.3.1). Wide, smooth There should be enough space to Estimate the surface water discharge into main drains, and drainage routes construct drains with adequate capacity to calculate the required drain dimensions to accommodate accommodate the estimated discharge, the flow. Avoid aligning the drain where there is not without sharp bends where overtopping enough space (e.g., between densely built houses). If the can occur potential routes are too narrow, consider subdividing the catchment and building several smaller drains. Proximity of houses to Roof water and gray water from houses Plan the drain alignments to optimize the number of planned or existing can represent a significant proportion of households that can be connected to the drainage drains the surface water in a community network. the drainage design will call for more conven- struction used in MoSSaiC projects—concrete tional construction methods. Factors such as main drains constructed according to standard drain size, function, and maintenance will engineering specifications, and smaller low- determine which form of construction is cost drains constructed using appropriate and appropriate. For example, main drains will readily available local materials. almost certainly need to be constructed from reinforced concrete due to their high dis- 6.5.1 Reinforced concrete block drains charge and often high velocities (especially on Drains that will have large discharge volumes, steep slopes). Small household drains with high flow velocities, or debris-laden flows lower flows could be constructed using pre- must be robustly constructed to ensure their cast concrete drain elements or lower-cost durability and reliability. Government engi- materials. neers may be accustomed to constructing rub- Use this section to identify key design ele- ble wall drains for large-scale projects (fig- ments for the two main types of drain con- ure 6.26), but these can be expensive and not 2 3 8    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E 6.5.2 Low-cost, appropriate technology FI G U R E 6 .2 6  Rubble wall as part of drain for drain construction construction Low-cost solutions that use appropriate local materials can engage community members in contributing ideas and construction knowl- edge, raise awareness of good slope drainage practices, and be a valuable means of fostering project sustainability. While the advantages of reinforced concrete block drains include a durable structure and proven design proto- cols, low-cost approaches can be appropriate for low drain discharges and flow velocities in the following circumstances: • For connecting small numbers of houses to main drains • In less accessible locations, such as upper slopes, where materials for concrete drains cannot be transported or carried As rubble wall structures are generally expensive, it is a good practice to review alternatives such as concrete block construc- tion carefully. F IGUR E 6. 2 7  Example of concrete block drain design a. Typical section of reinforced concrete block drain 10 mm rendering compacted granular backfill always appropriate for community-based drainage projects. For MoSSaiC projects, rein- 12 mm dia. principle forced concrete block drains (also called steel bars at 0.3 m 200 mm O.C. 150 mm concrete U-drains or open drains) are often the most 0.3 m block (all cores filled with concrete) suitable option for main intercept and 150 mm concrete base 1 layer # 65 BRC downslope drains, footpath drains, and many compacted base of the secondary (tributary) drains. Although there are different standard designs for reinforced concrete block drains b. Typical section of reinforced concrete block drain for around the world, the essential elements of intercepting water across a slope excavation, a compacted base, steel reinforce- specification as above (for typical block drain) plus the following design specification: ment, cast concrete invert, concrete block sidewalls with weep holes, and a compacted weep holes—distance to be determined on site (typically 3 m spacing) granular backfill are likely to be similar (fig- ure 6.27). One construction specification for MoSSaiC projects is that the tops of the drain sidewalls should be flush with the slope sur- face to enable surface water to flow into the drain. The design and construction of con- crete drains should be carried out in conjunc- tion with that of other structures, such as Note: Each country can be expected to have a slightly different standard design footpaths, that may be part of a MoSSaiC to suit local conditions and material availability. project. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 3 9 • On unstable slope sections that need sur- drain construction methods are more likely face drainage but where slope movement to be adopted as a self-help measure by may be reactivated. individual households. • Speed and flexibility of construction. A low-cost, appropriate technology drain Unlike concrete block drains, the plastic- construction method was developed by govern- lined drains can be quickly constructed or ment task teams and community residents dur- dismantled. New drains can be installed ing a MoSSaiC project in St. Lucia. The drain relatively easily to accommodate slope consists of a shallow trench lined with durable movement on progressive slides or the con- polythene sheeting (typically sunlight-stable struction of new houses or paths (fig- polythene) which makes the drain water tight ure 6.29). and prevents infiltration. To keep it in place, the polythene is overlaid with a light-weight steel- Certain communities in the Eastern Carib- wire mesh molded to the shape of the drain and bean have been sufficiently engaged with anchored to the ground with U-shaped pegs MoSSaiC projects to use their own initiative made by bending lengths of reinforcing rod. These materials cost considerably less than F IGUR E 6. 2 9  Installation of plastic-lined those required for constructing a reinforced drain concrete block drain of equivalent size. Beyond its cost-effectiveness, some of the advantages of this drain construction method include the following: • Ease of transport. Materials can readily be carried to sites that are difficult or prohibi- tively expensive to transport materials to for concrete block drain construction (fig- ure 6.28). • Rapid uptake. Low cost, and the ease of a. Low-cost drain being installed by residents. transport of materials, means that such F IG U R E 6 . 2 8  Shipping construction material to site can be expensive Shipping sand and cement can add significantly to the cost of conventional drain construction in more remote island locations. Here, material is being shipped some 18 miles on an inter- b. Completed drain, with household gray water island ferry to reach the community. connections. 2 4 0    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E and construct low-cost drains in appropriate 6.5.3 Combining different drain locations that supplement, and connect to, the construction approaches main drainage network (figure 6.30). Such ini- tiatives are evidence of a community taking It might be premature to expend funds on the ownership of good slope management prac- construction of concrete block drains unless tices for landslide risk reduction. there is sufficient evidence that doing so will improve slope stability. Where the slope is extensive and multiple signs of instability are present, a possible solution is to use a combi- FI G U R E 6 . 30  Community innovation and nation of drain construction approaches: skills at work after project completion • Construct concrete block drains upslope of unstable slope sections to intercept surface runoff and discharge water safely off the slope. • Use low-cost or temporary drains (such as that discussed in section 6.5.2) across active areas of the landslide or previously failed material (figure 6.31). This latter approach allows an assessment to be made of stability improvement that sur- face drainage affords in complex landslide zones without expending all available funds at the initial stage. F IGUR E 6. 3 1  Combination of block drain and low-cost drain Community residents selected the location, excavated a trench, and constructed a low-cost These drains were used in a former landslide drain to capture surface water and convey it to area, the lower portion of which was poten- a main concrete drain. tially still unstable. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 4 1 6.5.4 Construction design details F IGUR E 6. 32  Number of days slope surface is saturated per year with and Define the construction specification for each without household water capture drain section in the final drainage plan accord- number of days soil saturated ing to the drain alignment, size, function, and 140 construction type. Incorporate additional total rainfall and during example year 120 piped water added to slope drain construction design details using 100 table 6.4 as a guide. 80 60 40 100% roof water and 20 50% piped water capture 6.6 INCORPORATING 0 HOUSEHOLD WATER 0 10 20 30 40 50 60 70 housing density CAPTURE INTO THE PLAN (as percentage of slope area) Note: Annual rainfall = 1,868 mm, slope area = In areas of high housing density, the capture 7,000 m2, slope surface saturated hydraulic and controlled drainage of water from houses conductivity, Ksat = 1 x 10−7 m3 s−1, average house footprint = 60 m2, monthly average water supply per is a vital element of the final drainage plan for house = 2,887 gal. landslide hazard reduction, as discussed in section 6.3.8. Household water consists of roof water (rainfall that is intercepted by roofs and chambers for connecting multiple pipes or runs off ) and gray water (wastewater from small household drains. A detailed house-by- kitchens, washing machines, washbasins, and house survey of actual guttering lengths and showers—i.e., any wastewater except that from parts will be undertaken during the prepara- the toilet, which is termed black water or sep- tion of work packages (chapter 7) after sign-off tic waste, and which should not be discharged of the final drainage plan. into surface drains constructed as part of a MoSSaiC project). 6.6.1 Houses requiring roof guttering Increasing the housing density and volume Roof guttering can be an effective way of inter- of publicly supplied water discharged onto a cepting rainwater and reducing surface water slope can result in a corresponding increase in runoff in order to improve slope stability. The the number of days the soil is saturated per added benefits to the household include the year, if there is no drainage (figure 6.32). This opportunity to harvest rainwater for domestic level of saturation is significantly reduced by use (see section 6.6.2) and a reduction in the capturing roof water and gray water. negative effects associated with uncontrolled Having confirmed the alignment of drains roof water runoff (protecting house founda- within the community, determine which tions from erosion, increasing the service life houses need to be connected to drains—priori- of the roof and walls, and reducing problems tizing zones where household water signifi- with damp and flooding). cantly contributes to surface water infiltration Identify how many houses require roof gut- and slope instability. Use the guidance in this tering as part of the project and indicate their section to identify the components that are inclusion on the final drainage plan. Use the required for each house (such as roof gutter- following questions as a guide: ing, water tanks, gray water pipes, drain con- • Is the house in an area where surface water nections, and hurricane straps). This process and household water are significantly con- is illustrated in figure 6.33. tributing to the landslide hazard? Estimate the quantity and cost of materials assuming a unit cost per house for each of the • Is there a problem with stagnant water or prioritized houses and the approximate num- erosion of the foundations caused by water ber of shared components, such as concrete from the roof or a neighbor’s roof? 2 42    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E TAB L E 6.4  Construction design details related to aspects of drain alignment LOOK FOR WHERE ACTION: DRAIN CONSTRUCTION DESIGN Locations where • On steep drain gradients with • For existing drains and footpaths, the drain drains could be high flow velocities (especially depth can often be increased by building an overtopped where there are steps or bends upstand. in the channel) • Baffle walls can be added where drains join • Where drains connect (especially to prevent any flow jumping the connection. if the angle of the drain • Make sure that bends in drains have a connection is high—e.g., a right sufficient radius for the flow velocity, and angle) ensure sufficient freeboard (including the use • Drains adjacent to footpath of baffle walls where necessary) to contain steps where the tread of the the superelevation of the water surface. step is too low • Avoid the use of chambers or enclosed • Where debris could accumulate drains where possible. and block the drain • Incorporate debris traps (and widen the drain). Locations where • Culverts • Widen and deepen existing culverts and flow could be • Existing drains that are under- drains to accommodate the flow. Maintain constricted sized steep drain gradient through culverts to prevent blockage. • Where drain size cannot be increased, flow should be diverted into new drains. Locations where • All drains • Construct the top of drain sidewalls flush surface water with the slope surface. This ensures surface could be water flow capture and prevents potential prevented from undermining of the sidewall by erosion. Use entering the drain well-compacted fill to make up any overexcavation along channel sides. • To maximize subsurface soil water flow capture, include weep holes on the upslope channel side. This helps to ensure flow does not undermine the drain. Locations where • Bare soil on slopes adjacent to • Provide a sloping apron adjacent to the surface water the drain channel, particularly for stepped channels, to runoff and drain • High-velocity turbulent drain return any out-of-channel splashing to the flows could erode flows (steep, stepped drains, channels. the slope or especially at bends in the • Include additional reinforcement in the cause damage to channel) construction design. the drain • Natural drainage channels into • Steps in channels should be sloping, not which the main drains discharge horizontal. Multiple small steps should be and where the increased flow designed, rather than a few large steps. could erode the channel sides • Rip-rap can be used to armor the sides and base of natural channels, and gabion baskets or rubble walls can be designed to protect and retain steep channel sides. Safeguards • Housing proximity to drains • Ensure, where possible, that drainage channels are not placed too close to housing structures and that considerations of channel design are viewed within the context of all relevant safeguard require- ments. Source: Hui, Sun, and Ho 2007. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 43 FI G U R E 6 . 33  Process for incorporating household water capture F IGUR E 6. 3 4  Retrofitting roof guttering into the drainage plan Proposed drainage plan  Account for details on site; identify number of houses requiring • Roof guttering Design household measures • Water tanks (if included in and connections to drains project) based on prioritized roof  • Gray water pipes water and piped water  • Direct connections to drains discharge calculations • Indirect and shared connec- tions to drains (connection chambers) • Hurricane straps (if included in project)  Draw final drainage plan and estimate project cost (section 6.7)   Harvesting for drinking water Community sign-off Decision maker sign-off Rainwater harvesting installations that are designed to provide drinking water typically comprise the following major components: • Is there already guttering on part of the roof? catchment area (usually a roof ), guttering, • How easy would it be to fit roof guttering prestorage filtering, storage in a tank, and (figure 6.34)? poststorage treatment. Figure 6.36 illustrates typical systems for filtering and purifying roof • How will the downpipes connect to the water for human consumption. main drainage network? Use section 6.6.4 to The cost of a small water tank is typically identify the most appropriate means of con- only half that of a complete system (fig- nection. ure 6.37); there are additional recurrent costs to the homeowner to maintain, clean, and 6.6.2 Rainwater harvesting replace filters and other components. These set-up and maintenance costs will likely be Providing water for washing and cleaning prohibitive for MoSSaiC projects (and resi- The harvesting of rainwater captured by the dents) unless the project objectives include roof can be a major priority for some commu- provision of rainwater harvesting for drinking nities if there is no public water supply, or if water and there is associated funding for this the supply is interrupted on a regular basis and purpose. for long periods (figure 6.35). Roof guttering is Assessment of quantities an inexpensive way of collecting significant volumes of water for household use for wash- If the project provides for installing household ing and cleaning purposes. Homeowners may water tanks in conjunction with roof gutter- already be collecting rainwater from part or all ing, identify which households will benefit of their roof area using a drum (ideally covered most and determine whether to provide a with a fine mesh to prevent mosquitoes) or a standard domestic water tank or connect the modern domestic water tank. roof guttering to an existing tank. For each 2 4 4    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E FI G U R E 6 . 35  Rainwater harvesting a. Many communities have unreliable water b. Providing water tanks as part of a MoSSaiC supplies and have to make what provision they can intervention to those residents most in need can to harvest rainwater. be a cost-effective means of rainwater harvesting. FI G U R E 6 . 36  A system for filtering and purifying water for human consumption a. Rainwater harvesting for drinking water can be a b. Filtration unit running costs can generally only relatively expensive installation because of the be justified in the most deserving of cases. filtration systems required. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 4 5 6.6.3 Gray water capture F IG U R E 6 . 37  Cost components of small domestic rainwater harvesting system Providing communities with a piped public postfilter water supply can mean that water from houses 8% (a point water source, in slope hydrology gutter tank labor terms) can be a significant source of surface 30% 16% runoff and infiltration into the slope if left unmanaged (figure 6.38). Drainage design should account for house- hold gray water by making provision for houses to be connected to the main drains prefilter 8% wherever feasible. If homeowners are chang- ing the layout of their home, it is important to tank materials 38% discuss ways in which they plan to connect new bathrooms and kitchens to the drain. Source: University of Warwick 2003. Note: A small system is here considered to be 600 L. Costs are based on fieldwork in southern Uganda. F IGUR E 6. 3 8  Capturing gray water from showers and washing machines house identified for roof guttering provision, ask the following questions: • If the house is already harvesting roof water: —— Is the water being harvested from the whole roof? If not, the roof guttering will need to be configured to do so, or to deliver excess water directly to a drain. —— Is there adequate overflow connection from the tank to a drain? If not, such a connection will need to be made (see section 7.5.6). —— Are there sufficient measures for pre- venting mosquitoes breeding in the tank? • If roof water is not currently being har- vested: —— Would the homeowner like to be able to harvest rainwater from the roof? —— Would the homeowner be willing or able to provide a drum or tank for collecting water? —— Would the household benefit from being In the lower photograph, gray water discharges provided with a water tank as part of the to a former landslide on which the house has project? If so, is there a way of prioritiz- been rebuilt. ing the neediest households? 2 4 6    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E Identify how many houses require gray then by pipe to the drain, or construction of a water connections as part of the project and small drain to connect to the main drain. indicate their inclusion on the final plan. Use If the homeowner has already made some the following questions as a guide: provision for drainage (earth drains, trenches, concrete-lined drains), use the following ques- • Is the house in an area where surface water tions to help decide how to incorporate these and household water are significantly con- drains into the plan: tributing to the landslide hazard? • Can the existing drains be connected to the • Has the house already been selected for proposed drains? roof guttering installation? If so, it is likely to also require gray water connection to the • Do they need to be improved to prevent drains. leakage? • What form of connection is most appropri- • Do they need to be extended to connect ate? Use section 6.6.4 to identify the most with the proposed drains? appropriate means of connection. • Is the current capacity sufficient to cope 6.6.4 Connection to the drainage with additional flow from new roof gutter- network ing or gray water connections? • Can a low-cost method of drain construc- Once it has been decided which houses should tion be used? (See section 6.5.2.) receive roof guttering, water tanks, and gray water connections, determine the method for • Are there preexisting connections to drains connecting the downpipes, water tank over- (roof guttering, water tank overflow, gray flows, and gray water pipes to the drainage water)? network (figure 6.39). Household connection • Is the homeowner willing and able to make options include direct pipe connections, con- the necessary improvements? (This should nection by pipe to a concrete chamber and be encouraged as a form of in-kind contri- bution to the project.) If there are no connections: FI G U R E 6 . 39  Gray water and roof water connections to block drain • How far is it to the nearest existing or pro- posed drain? • Can the house be connected directly to the drain? • If it is too far or too complicated to connect pipes directly, is it appropriate to route the pipes via concrete connection chambers or a minor new drain? Direct drain connections Houses can be connected to existing or pro- posed block drains simply and inexpensively if the drain is adjacent to the house (figure 6.40a). Connections can sometimes be retrofitted to cross footpaths (figure 6.40b), but this is not ideal from either a hydraulic standpoint or in terms of residents’ safety when using the foot- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 47 F IG U R E 6 .4 0  Household connections to main drains a. Connection of household roof water to a nearby b. Provision should be made for household water main drain. connections before a footpath is constructed. c. It is important to tidy up residents’ makeshift gray water connections when drains have been built. path. If new footpaths are to be constructed as chambers can be connected via pipes to a main part of the project, allow for household con- drain. nections to be integrated into the design. Assessment of quantities Pipes and connection chambers On the final drainage plan, indicate how roof Concrete chambers can be used to collect guttering and gray water from each house will water from several downpipes and gray water be connected to the drainage network. Esti- pipes in cases where the distance between mate the costs of materials required based on houses and drains prohibits direct connec- approximate unit costs per length of drain or tions. The water can then be routed to the concrete chamber. A detailed quantity survey main drain in a single large pipe. Concrete and preparation of work packages should be chambers can serve to collect water from sev- undertaken once the plan has been approved eral houses (figure 6.41), and a sequence of (chapter 7). 2 4 8    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E FI G U R E 6 .41  Concrete chambers connecting water from multiple houses to a single collection point with an outflow pipe to a main drain 6.6.5 Hurricane strapping F IGUR E 6.42  Fragile roof structure Roofs are an important part of a surface water management strategy, especially in communi- ties with high housing densities. In countries affected by tropical cyclones, the roof must be structurally sound and able to withstand not just heavy rainfall but also hurricane-force winds. Retrofitting roofs with hurricane straps should be included in the project wherever possible (figure 6.42). Comprehensive retrofitting using a range of building ties on the structure strengthens a Roof structures are typically relatively fragile, house’s structural frame to create a continuous with galvanized sheeting nailed to joists and load path (IBHS 2002). A continuous load wall plates. path is a method of construction that uses a system of wood, metal connectors, and fasten- ers such as nails and screws to connect the they are rarely seen as a priority in vulnerable structural frame of the house together from households. Typical installations on a modest- roof to foundation (figure 6.43). The house is sized house should involve the fitting of some thus more likely to withstand a hurricane 16–20 hurricane straps to the joists and rafters event and remain intact. Hurricane straps are (figure 6.44). There are a variety of hurricane the primary means of strengthening the roof of straps available; product selection will depend most one- or two-story structures. Although on local availability and house structural the straps are inexpensive and easy to install, details. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 4 9 6.7 SIGNING OFF ON THE FINAL FI G U R E 6 .43  Hurricane strapping ties DRAINAGE PLAN Roof to top plate connection: Fastens the roof to the top of the The process for signing off on the final drain- wall age plan will typically include the following Top plate to stud connection: Ties steps: the top of the wall to the wall • Drawing up the final drainage plan studs • Estimating project costs Floor to floor • Revising the plan according to the project connection: Ties budget the second story to the first story • Reviewing the plan (MCU, government task teams) Stud to mudsill connection: Fastens • Consulting with the community and other the wall studs to the stakeholders, and incorporating any revi- bottom of the wall (mudsill) sions into the plan Mudsill to foundation • Signing off on the plan with the community connection: Anchors the bottom of the and decision makers. wall (mudsill) to the foundation The MCU should set a realistic schedule for Source: Image courtesy of Simpson Strong-Tie Company Inc. this process and support the task teams in completing each step. Build in sufficient time for consultation with the community and use a variety of participatory approaches to allow F IG U R E 6 .4 4  Roof hurricane strap different groups to contribute their opinions on the drainage plan (such as formal meetings and informal conversations). Keeping to the advertised schedule builds community trust and engagement. 6.7.1 Drawing the final drainage plan and estimating costs The final drainage plan should include the fol- lowing: • The project name; community name; date; plan revision number; names of those involved in designing and drawing the plans; and any names or logos of funders, government ministries, and other agencies involved (according to local protocols) • Proposed drain locations, lengths, con- struction types, and internal dimensions (calculated for main drains and estimated for minor drains) 2 5 0    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E • Houses with identification numbers or plan and estimated costs have been approved, names to allow cross-reference to a list of the cost estimates for each item will be fully households requiring roof guttering, gray specified for preparation of work packages water pipes, and connections to drains (and (chapter 7). provision of water tanks and/or hurricane straps, if included in the project) 6.7.2 Community agreement Display the drainage plan (figure 6.45) at suit- • Connection chamber locations able locations within the community, such as • Debris trap locations at bars and shops (figure 6.46a). Walk through the community with the plan to obtain further • Any other relevant details for estimating feedback from community members and other project costs stakeholders or decision makers (figure 6.46b). • Reference to any relevant supplementary Members of the government and community plans or documents. task teams involved in community liaison, design of the drainage plan, and implementa- Estimate the total project cost based on the tion of the proposed works should be part of proposed drain lengths, dimensions, and con- this community visit, and should be prepared struction types, and the approximate quanti- to answer any issues residents may wish to dis- ties of each of the household drainage compo- cuss. Convene a community meeting to dis- nents. Obtain local unit costs for each cuss, refine, and agree on the plan. Govern- component, and use these to calculate total ment and community task team members project cost. Table 6.5 shows how a spread- should attend the meeting, together with sheet for calculating initial project costs could members of the MCU and relevant stakehold- be organized. Once the proposed drainage ers. TAB L E 6.5  Initial costs for drain construction and for household water connections a. Drain construction CROSS-SECTION APPROXIMATE UNIT TOTAL ITEM FOR CONSTRUCTION DIMENSIONS LENGTH (m) COST COST New main concrete block drains New minor concrete block drains Existing drains to make-good New soft engineered drains Total b. Household water connections APPROXIMATE UNIT TOTAL ITEM FOR CONNECTION NUMBER (n) LENGTH (m) COST COST Roof guttering n houses — Water tanks n houses — Hurricane straps n houses — Gray water pipes — Connecting pipes — Connection chambers n items — Household drains — Total CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 5 1 FI G U R E 6 .45  Extracts from a final drainage plan for agreement with stakeholders and sign-off 33 6.1 63 64 FINAL DRAINAGE PLAN 35 67 N 39 62 60 8.1 30extract) (example 4.1 34 61 31 36 68 38 5.1 29 3.4 27 4.2 6.2 7.1 69 37 5.2 40 59 44 58 8.2 28 25 70 LEGEND (example extract from plan) 26 41 43 3.3 24 54 existing drains (including those needing 45 56 42 57 repair) 4.3 23 7.3 46 55 7.2 53 proposed new drains (see table for 47 22 49 52 calculated or estimated dimensions) 51 3.2 6.3 3.1 48 50 proposed soft engineered drains 21 20 3.2 concrete connection chambers 1 19 1.2 5 houses (numbered for identification) 16 15 2 1.3 17 2.3 3 18 1.4 2.2 10 12 1.1 14 7 8 13 4 2.1 11 approx 50m 6 9 PROPOSED DRAINS FOR (example extract from plan) 5 internal Drain Item dimensions (m) Length (m) w h DRAINAGE GROUP 1 1.1 intercept drain and connection from connection chambers to drain 0.3 0.3 25 1.2 make good existing drain and continue to join drain 3.2 0.6 0.6 61 1.3 minor drain to capture runo and household water 0.3 0.3 37 1.4 soft engineered intercept drain to capture surface runo 0.3 0.3 16 DRAINAGE GROUP 2 2.1 make-good path drain 0.3 0.3 42 2.2 main downslope drain to existing concrete drain 0.6 0.6 30 2.3 soft-engineered drain to intercept runo behind house 0.3 0.3 11 DRAINAGE GROUP 3 3.1 downslope drain (incl. pipe connection from house 2) 0.4 0.4 112 3.2 main downslope drain (along existing drainage route) 0.6 0.6 87 3.3 main intercept drain to connect footpath drain to 3.2 0.75 0.75 68 3.4 make-good path drain 0.3 0.3 50 DRAINAGE GROUP 4 4.1 main intercept drain above concrete path 0.4 0.4 105 4.2 main downslope drain (reroute to avoid house 41) 0.6 0.6 45 4.3 main drain along existing drainage channel (connect 3.2) 0.75 0.75 130 2 52    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E 6.7.3 Formal approval and next steps FI G U R E 6 .46  Community involvement in finalizing the drainage plan Once the final community consultation pro- cess is completed, submit the plan to the rele- vant authorized ministry for formal approval. In conjunction with the process for obtain- ing formal approval for the plan, identify issues regarding access from one property to another, landownership, the provision of pipe work requiring neighbor permissions, and so on. Review and comply with relevant safeguards and obtain residents’ or landowners’ agree- ment to relevant aspects of the proposed drain a. Displaying the plan within the community is important. alignment or construction process. Submit the final approved drainage plan to the landslide hazard and engineering team or other implementing agency responsible for developing work packages (chapter 7). MILESTONE 6: Sign-off on final drainage plan b. Walk though the community with the plan and have as many on-site discussions as possible. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 5 3 6.8 RESOURCES 6.8.1 Who does what CHAPTER TEAM RESPONSIBILITY ACTIONS AND HELPFUL HINTS SECTION Understand drainage alignment • Review principles of drainage design for surface water 6.3 principles and drain types capture in communities Ensure the final drainage plan • Identify local experts in drainage design for consultation 6.2 meets required engineering and/or incorporation into the landslide assessment and design standards engineering task team MCU Ensure the community is fully • Identify local community development experts for 1.3.3 consulted with on the final consultation and/or incorporation into the community drainage plan liaison task team Coordinate with government task team Understand and apply methods • Review equations and online tools 6.3.2–6.3.8 for estimating slope surface Helpful hint: It is useful to have one individual assigned water discharge and household this important task, so that his or her knowledge base is water discharge built up with regard to available estimation methods and Understand and apply methods approaches. to calculate drain dimensions for design discharges Draw first version of final • Confirm and refine drain locations on site 6.4 drainage plan to indicate drain • Identify both conventional and low-cost engineering alignment and construction construction materials and design details details • Incorporate local construction practices into the design • Use the slope process zone map and calculations of 6.6 Optimize the number of houses household water capture to identify areas where Government task that can be linked to drains household drainage will be most beneficial teams • Incorporate all drain construction and household 6.7.1 Develop the final drainage plan connection details into the plan and cost estimate • Estimate quantities and costs (drain lengths, household connection components) • Discuss draft plan on site with residents and at a 6.7.2 Discuss proposed plan with the community meeting community • Display the plan at a suitable location in the community Coordinate with community task teams • Secure formal stakeholder agreement and decision-mak- 6.7.3 Secure approval of final drainage er approval plan Helpful hint: To ensure safeguard compliance, obtain any necessary written agreements from stakeholders. Community task • Identify local slope water management and construction 6.5 Contribute local construction teams good practices and collaborate with government knowledge and practices engineers to incorporate them into the drainage plan Contribute local knowledge to • Facilitate community feedback to the final drainage plan 6.7 the final drainage plan prior to formal sign-off Coordinate with government task teams 2 5 4    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E 6.8.2 Chapter checklist SIGN- CHAPTER CHECK THAT: TEAM PERSON OFF SECTION 99The landslide assessment and engineering task team has sufficient capacity or 6.1.3 support from an expert/consultant for developing the final drainage plan 99An appropriate drainage alignment pattern identified, discharge into drains 6.3 estimated, and drain dimensions calculated 99Detailed drain alignments confirmed on site and drain dimensions revised if 6.4 necessary 99Proposed drainage plan drawn up 6.4 99Drain construction types and details specified 6.5 99Low-cost, appropriate technology engineering approaches to drain construc- 6.5.2 tion considered 99Houses for roof guttering, water tanks, and hurricane straps identified, and 6.6 connections to drains designed 99Final drainage plan prepared 6.7.1 99Quantities and costs estimated 6.7.1 99Plan discussed and revised in conjunction with community and stakeholders 6.7.2 99Milestone 6: Sign-off on final drainage plan 6.7.3 99All necessary safeguards complied with 1.5.3; 2.3.2 6.8.3 Local designs for concrete drains, countries. See, for example, information from catchpits, and baffles the Geotechnical Engineering Office, Civil Engineering and Development Department, This section provides examples of typical Hong Kong SAR, China, available online at design drawings for surface water drains. http://www.cedd.gov.hk/eng/publications/ Reinforced concrete block drains are well manuals/index.htm. suited to MoSSaiC projects. The materials are Several commonly used drain types are dis- generally readily available and can be carried cussed below, along with conceptual sketches by hand over short distances, and the method and useful guidance on design issues of construction is familiar to local contractors. (table  6.6). This information provides a con- Typical drawings are shown in figure 6.27. text in which to review and refine local drain It is helpful to compile a set of design draw- designs. ings to accompany the final drainage plan and to guide estimation of project costs. Such drawings will be required in the development of work packages for contractors (chapter 7). TAB LE 6. 6  Illustrative drawings for drain design First, try to identify examples of relevant DRAIN TYPE/DESIGN DETAILS FIGURE drainage design drawings from other local Reinforced concrete block (downslope) 6.27 projects that use local expert knowledge and Reinforced concrete block (intercept) 6.27 experience, and will be familiar to community- based contractors. These could include con- U-channel 6.47 ceptual drainage plans or detailed construc- Baffle wall junction 6.48 tion design drawings for specific drain types Debris trap 6.49 and components. Stepped channel 6.50 To supplement local designs, refer to simi- Catchpit junction 6.51 lar types of surface water drains used in other CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 5 5 F IG U R E 6 .47 U-channel Impervious surface This dimension varies to suit fall on channel 1 20 Dimensions of U-channel min. H/2 Nominal size of Thickness t Thickness b channel H (mm) (mm) (mm) Design depth 225–600 150 150 H /2 H 675–1,200 175 225 b t H t Source: GCO 1984. Reproduced with permission of the Head of the Geotechnical Engineering Office and the Director of the Civil Engineering Department, Hong Kong SAR, China. Note: U-shaped channels are used for small drains in many countries. Construction requires the casting of concrete U-shaped drain sections prior to installation. Some on-site instruction may be needed to familiarize contractors and laborers with this process (WHO 1991). The figure shows typical specifications commonly used in Hong Kong SAR, China. F IG U R E 6 .4 8  Baffle wall junction Min. d + 450 mm measured from lowest invert of the stepped channel Varies but > h/2 d = s + H/2 10 1 300 mm h/ 2 b h SECTION A-A 600 mm Concrete apron t A A Baffle wall 5H H t 600 mm Concrete apron PLAN Source: GCO 1984. Reproduced with permission of the Head of the Geotechnical Engineering Office and the Director of the Civil Engineering Department, Hong Kong SAR, China. Note: A downslope drain can be connected to a cross-slope drain at the base of a slope by using (1) a baffle wall at the downslope side to prevent overtopping and (2) a concrete apron on the immediate upslope section of the downslope drain to contain and divert any splash back into the drain. 2 5 6    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E FI G U R E 6 .49  Typical debris/sand trap Cover slabs if required Inlet Max. design water level 300 min. 1 in F 300 min. h 300 D + 150 min. 0.25D 375 min. 375 min. D Fall 0.25D 1 in 40 Outlet 50 thick perforated face slab Graded stone filter lower layer size 150 mm, upper layer size 40-75 mm SECTIONAL ELEVATION L 750 min. A W B A SECTIONAL PLAN 25 x 16 m.s. flat bar 16 dia. m.s. bar at 100 c/c 150 dia. holes W SECTION A-A Note : (1) All dimensions in millimetres. (2) Normally for drains of 900 mm dia. and below. For bigger drains and steep terrain, sand trap should be specially designed. (3) Size Depth : < 750 Width : > 3B Length : L = 4.8D0.67 h0.5 F-0.5 > 4B (4) Graded stone filter should be crusher run granite aggregate. (5) Capacity DWL to be according to size and nature of catchment, providing detention time not less than 5 minutes for max. design flow of inlet. Source: GCO 1984. Reproduced with permission of the Head of the Geotechnical Engineering Office and the Director of the Civil Engineering Department, Hong Kong SAR, China. Note: Debris traps can be combined with a catchpit and sand/sediment trap. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 5 7 F IG U R E 6 . 5 0  Stepped channel A Top inner edge of channel Design channel depth, D α B Fall between 1:10 and 1:50 A 300 mm max. B Longitudinal Section Masonry facing on cement mortar or concrete apron Finished 500 mm 500 mm slope profile Min. fall Min. fall 1:10 1:10 D W/2 300 mm max. /2 W B T W T Section A - A Nominal size T (mm) B (mm) D (mm) W (mm) 300 80 100 350 375 100 150 540 450 100 150 575 525 100 150 615 600 100 150 650 675 125 175 740 750 125 175 775 900 125 175 850 Source: GCO 1984. Reproduced with permission of the Head of the Geotechnical Engineering Office and the Director of the Civil Engineering Department, Hong Kong SAR, China. Note: Stepped channels are used to reduce flow velocity, especially in downslope drains. The example in the photo is in Hong Kong SAR, China. 2 5 8    C H A P T E R 6 .   D E S I G N A N D G O O D P R A C T I C E F O R S LO P E D R A I N AG E FI G U R E 6 .51  Catchpit junction Varies Step irons to be 125 125 provided if height of catchpit exceeds 1500 125 thick wall and slab suitably reinforced Fall Arrangement of openings to suit min. site conditions 1 in 50 300 Concrete blinding SECTION A-A U-channel Step channel Concrete benching 125 Channel 250 A A Varies 250 Arrangement to openings to suit site condintions 125 125 125 Varies PLAN Source: GCO 1984. Reproduced with permission of the Head of the Geotechnical Engineering Office and the Director of the Civil Engineering Department, Hong Kong SAR, China. Note: Catchpits can be used to connect downslope and intercept drains. 6.8.4 References Premchitt, J., H. F. Lam, and J. M. Shen. 1986. “Rainstorm Runoff on Slopes.” Special Projects GCO (Geotechnical Control Office). 1984. Geotech- Division Report SPR 5/8699, Geotechnical nical Manual for Slopes. 2nd ed. Hong Kong Control Office, Hong Kong Government. Government. University of Warwick. 2003. “Roofwater Harvesting Hui, T. H. H., H. W. Sun, and K. K. S. Ho. 2007. for Poorer Households in the Tropics. Inception “Review of Slope Surface Drainage with Report. Domestic Roofwater Harvesting Research Reference to Landslide Studies and Current Programme R7833.” School of Engineering, Practice.” GEO Report 210, Geotechnical University of Warwick, Warwick, UK. Engineering Office, Government of Hong Kong Special Administrative Region. Wamsler, C. 2006. “Mainstreaming Risk Reduction in Urban Planning and Housing: A Challenge IBHS (Institute for Business & Home Safety). for International Aid Organizations.” Disaster 2002. Is Your Home Protected From Hurricane 30: 151–77. Disaster? A Homeowner’s Guide to Hurricane Retrofit. Tampa: IBHS. WHO (World Health Organization). 1991. Surface Water Drainage for Low Income Communities. Geneva: WHO. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 5 9 “The quality of site supervision has a major influence on the overall performance and efficiency of construction projects. Inadequate supervision is believed to be one of the major causes of rework.” —S. Alwi, K. Hampson, and S. Mohamed, “Investigation into the Relationship between Rework and Site Supervision in High Rise Building Construction in Indonesia” (1999, 1) CHAPTER 7 Implementing the Planned Works 7.1 KEY CHAPTER ELEMENTS 7.1.1 Coverage This chapter provides guidance on contracting Emphasis is placed on the critical role of site and constructing MoSSaiC (Management of supervisors, working in partnership with com- Slope Stability in Communities) drainage works munity contractors. The listed groups should in communities to improve slope stability. read the indicated chapter sections. AUDIENCE CHAPTER F M G C LEARNING SECTION   How to prepare work packages 7.3    Importance of site supervision during construction 7.5.1   Good practices in construction 7.6   Practices to be avoided in construction 7.7    Ensuring works are completed to the required standard 7.8 F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors 7.1.2 Documents CHAPTER DOCUMENT TO BE PRODUCED SECTION Bill of quantities 7.3.1 Work packages 7.3.2 Materials procurement plan 7.3.3 Schedules of construction defects and outstanding works 7.8 2 61 7.1.3 Steps and outputs STEP OUTPUT 1. Prepare work package and request for tender documentation Work packages for • Prepare a bill of quantities for the planned works implementation of drainage • Incorporate appropriate contingency and any double-handling costs (i.e., where intervention to material has to be delivered to sites where access is difficult and requires the reduce landslide establishment of a storage site between delivery and construction site locations) hazard • Decide on work package size that maximizes community engagement and meets procurement requirements • Prepare design drawings and plans to accompany each work package • Identify an appropriate plan for procuring materials depending on the community contracting approach, community capacity, and project procure- ment requirements 2. Conduct the agreed-upon community contracting tendering process Briefing meeting • Identify potential contractors from the community and provide briefing on for contractors proposed works and work packages, emphasizing the need for good construc- held; community tion practice contracts awarded • Invite tenders from contractors, providing assistance or training on how to submit a tender document • Evaluate tenders, award contracts, and brief contractors on safeguards 3. Implement construction Briefing meeting • Select experienced site supervisors for community held; construction • Authorize start of construction and meet with the community to discuss the under way construction process and introduce site supervisors • Closely supervise the works to ensure good construction practices; clear communication among contractors, supervisors, community, and the MoSSaiC core unit; and timely disbursement of funds for procurement of materials and payment of contractors/laborers 4. Sign off on completed construction Construction • Identify outstanding works completed and • Arrange for any necessary repairs or minor modifications signed off on • Sign off on completed construction and pay withholding payments to contractors 7.1.4 Community-based aspects basic drainage infrastructure has not kept pace with rapid unauthorized housing construction. The chapter involves the selection and super- Community-based development projects often vision of contractors from within a community include drain construction to address flooding to construct the planned drainage works and and environmental health problems. MoSSaiC improve slope stability. has much in common with such projects (e.g., taking a community-based approach, using appropriate construction methods, and build- 7.2 GETTING STARTED ing local capacity) but with the vital additional requirement that the drains reduce the land- 7.2.1 Briefing note slide hazard. There are thus two key ingredi- ents for effective implementation of MoSSaiC Drainage construction for landslide hazard drainage works: high-quality construction that reduction adheres to the design specification and a com- Poor drainage is a common issue for vulnerable munity-based approach to engaging and work- urban communities where the provision of ing with contractors from the community. 2 62    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S MoSSaiC drainage works are based on a works that allows the community contractors formally agreed-upon drainage plan that spec- and the government task teams to work ifies drain alignments, designs, and construc- together effectively (figure 7.1). tion details (chapter 6). This plan is designed to address local landslide mechanisms, specifi- F IGUR E 7.1  MCU meeting to agree on cally, the infiltration of rainfall and household responsibilities during construction process water into the slope material (chapters 3 and 5). Implementing the planned works requires technical understanding of the rationale for the drain alignment and design, and skill in constructing drains and installing household connections that function as intended—allevi- ating the landslide hazard without creating additional hazards or drainage problems. MoSSaiC drainage works should be imple- mented using an appropriate form of commu- nity contracting to engage contractors and laborers from within the community to imple- ment the drainage works. Community con- The process for delivering effective drain- tracting can be broadly defined as “procure- age for landslide hazard reduction should ment by or on behalf of a community” (de Silva facilitate the following: 2000, 2). During this stage of the project, site supervisors play a vital role in both delivering • Construction procurement using an appro- high-quality construction and encouraging priate form of community contracting— community engagement. Hands-on site super- developing work packages from the drainage vision allows contractors to contribute their plan, preparing a bill of quantities, running a detailed knowledge of the hillside and local tendering process, and awarding contracts construction practices, while providing to contractors from the community instruction on detailed construction issues • Clear communication and feedback among and good construction practices. There should government engineers, site supervisors, be clear processes for evaluating the works contractors, and community residents— and disbursing contractor payments to ensure explaining the procurement and contract- that design and construction specifications are ing processes to all stakeholders, providing met. training for community task teams (depend- Implementation processes and good practices ing on the forms of construction procure- ment and community contracting selected), Using a community-based approach to deliver and providing formal and informal ways for good-quality drainage works in vulnerable community residents to participate urban communities requires coordination among government and community task • High-quality, hands-on supervision by teams. Government engineers and site super- experienced technicians and/or engi- visors may not be used to working with infor- neers—briefing contractors on drainage mal contractors in unauthorized communities design and construction specifications, set- and will need to adapt to this environment. ting out drain alignments on site, day-to- Similarly, contractors and laborers in commu- day site supervision during construction to nities may be unfamiliar with formal construc- ensure specifications are met and problems tion sector processes and practices. The resolved, reporting to the MCU on prog- MoSSaiC core unit (MCU) should therefore ress, and signing off on completed works to establish a process for implementing the allow contractors to be paid. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 63 A good site supervisor–contractor relation- tional capacity and project funding and pro- ship is important for delivering sound con- curement requirements, but the following struction and slope stability management general characteristics and goals can be recog- practices. Knowledge of such practices can nized (de Silva 2000, 3): come from traditional classroom training, but • Community members are involved in iden- is more likely to be developed on site during tifying needs and selecting a project. construction through practical experience and • Community participation is encouraged knowledge sharing. Site supervisors should be throughout project identification, prepara- familiar with good construction practices, tion, implementation, operations and main- help contractors achieve high-quality con- tenance, and is usually done through an struction, contribute to the learning experi- elected community project management ence of contractors and laborers, and mini- committee. mize any points of potential disagreement • Communities provide contributions in the between residents and contractors during form of labor, cash and/or materials. Their construction. In this regard, site meetings with contributions promote community owner- ship and hopefully eventual subproject sus- contractors (figure 7.2) are vital in setting out tainability. the works, reinforcing good practices, and building contractor confidence. MoSSaiC projects share these broad char- acteristics and goals in that they promote com- Community contracting munity participation and ownership through- A key element of the MoSSaiC approach is out the mapping and drainage design stages contracting works out to community-based (to which community members contribute contractors and laborers. This chapter intro- time and knowledge), and maintenance of duces the concept of community contracting completed works (also involving some form of for construction works, but does not cover dif- community contribution). A distinction of ferent procurement approaches and processes. MoSSaiC is that communities are not neces- Community contracting can take many sarily required to contribute labor, cash, or forms, depending on community organiza- materials for construction. For MoSSaiC projects, skilled contractors and laborers from within the community are F IG U R E 7. 2  Contractor site meeting contracted and remunerated for delivering good-quality drainage works that meet the required design and construction specifica- tions for reducing landslide hazard. This ensures that a substantial portion of external funding is retained in the community, and the self-esteem of contractors is built through the experience of completing for- mally contracted works. Community mem- bers not directly involved in construction can make in-kind contributions (e.g., by pro- viding secure storage for materials, water, and access across properties to the construc- tion site). An extensive study of 800 urban infrastruc- ture projects in India, Pakistan, and Sri Lanka in which the construction component was contracted to the community found that their overall performance was comparable to, or 2 6 4    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S better than, conventional microcontracts • Continue to communicate the purpose of the awarded to external contractors using a tradi- drainage intervention (to capture surface tional bid evaluation process (Sohail and Bald- and household water to reduce landslide win 2004). Additionally, hazard) as the basis for the drain alignment the performance of these [community part- and construction design. This understand- nered] projects in terms of socioeconomic ing is especially important for contractors elements was likely to far exceed that of con- and supervisors, as it will help guard against ventional microprojects. For example, the deviations from drain designs and construc- number of community labor days generated tion specifications, or poor construction by microcontracts injects significant money practices that may make drains ineffective. into the local economy (Sohail and Baldwin 2004, 201). • Stress the importance of supervision as a critical component in achieving a high- Table 7.1 shows the rank ordering of a quality drainage intervention and in main- number of performance indicators and their taining community engagement during associated yardsticks from the Sohail and construction. Baldwin study. This information can provide the MCU with initial guidance on which • Ensure that all relevant safeguards are project delivery components are most impor- addressed with both landowners and com- tant to monitor and keep on track during munity residents, especially those regard- implementation. ing drain alignments. 7.2.2 Guiding principles 7.2.3 Risks and challenges The following guiding principles apply in Project interruptions implementing planned works: Interruptions to projects because of protracted • Ensure that roles and responsibilities are institutional procedures or cash flow prob- agreed on, well defined, communicated, lems can be very damaging to morale. The and acted on. MCU and government task teams should be • Operate a transparent process for commu- proactive in preventing potential delays and nity contracting that builds confidence and offsetting their impact by making clear to the capacity for all involved. communities and contractors TAB L E 7.1  Yardsticks for selected community-based performance measures PERFORMANCE INDICATOR YARDSTICK Accuracy of preliminary technical estimates ± 5% Cost growth (final contract cost/initial contract cost) ± 9% Proximity of engineers’ estimated cost and initial contract cost ± 12% Time growth (final contract duration/initial contract duration) ± 20% Lead time (time required to commence works/contract duration) ± 20% Proximity of engineers’ estimated cost and final contract cost ± 25% Time between tender invitation and start of contract 20 days Time from approval stage to tender inviting (or equivalent) stage 50 days Time to start operation and maintenance after the contract is completed 65 days Source: Sohail and Baldwin 2004; data are from a survey of 800 community-based microprojects. Note: Shaded items indicate the components that are potentially most important for the MCU to monitor during implementation. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 6 5 • the time frame relating to the availability of struction practices. For their part, site supervi- funds, sors also have a pay incentive to see works completed quickly. It is therefore important to • the specific purpose of funds, and stress the critical nature of design details and • the precise point at which works can be good practice to all parties. allowed to proceed. Questionable practices Setting realistic expectations and following It is well known that any form of construction through with project delivery during the map- can be associated with questionable or corrupt ping and drainage design phases (chapters 5 practices associated with project planning and and 6) will reassure the community that the prebid stages, contract award and project works will actually be undertaken if they are implementation, and monitoring of the works. appropriate. Provision of mobilization funds The World Bank (2010) details a number of for all contractors is likely to be an important such activities and practices (listed in sec- prerequisite to a successful and timely project tion 7.10.4) that the MCU should be mindful of start. during implementation of the drainage works. Inadequate contractor briefing 7.2.4 Adapting the chapter blueprint to Ensuring that community contractors are ade- existing capacity quately briefed and supervised is one of the The effectiveness of a MoSSaiC project in most critical elements of a MoSSaiC project. reducing landslide hazard ultimately rests in Community-based contractors will ideally what is delivered on the ground. Use the put together teams of laborers and skilled matrix opposite to assess the capacity of the workers from within the community. The suc- MCU and the government and community cess in reducing landslide hazard rests on the task teams for implementing the planned quality of the construction that they deliver. drainage works. Initially, however, these teams may not have a 1. Assign a capacity score from 1 to 3 (low to clear understanding of the project rationale. It high) to reflect the existing capacity for is vital that contractors and their teams be each of the elements in the matrix’s left- briefed on the overall drainage plan, the pur- hand column. pose of the work package they are contracted to deliver, and the reasons for specific design 2. Identify the most common capacity score requirements and details in that package. If as an indicator of the overall capacity level. possible, contractors should be shown exam- 3. Adapt the blueprint in this chapter in ples of good and bad construction practices in accordance with the overall capacity level other communities and locations. (see guide at the bottom of the opposite Poor supervision and rushed work page). Good design can be diluted by poor site super- vision and by contractors wishing to speed up construction times to be paid sooner. Contrac- 7.3 PREPARING WORK PACKAGES tors should be made aware that completed works will be evaluated for construction qual- In preparation for tendering and construction, ity before payments are made. the drainage plan (chapter 6) should be broken Contractors’ desire to speed completion down into itemized components (materials, can be moderated by adequate (and often parts, and labor, and their associated costs—a close) supervision of works to ensure that bill of quantities), and manageable units of enthusiasm to complete the work program is work (work packages) to be undertaken by accompanied by an appreciation of good con- contractors. 2 6 6    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S EXISTING CAPACITY CAPACITY ELEMENT 1 = LOW 2 = MODERATE 3 = HIGH Government/community No previous experience with Some experience with Existing proven capacity in experience and organizational community contracting community contracting, but community contracting of base for contracting not related to construction construction construction works to community-based contractors Site supervision of No experienced site supervi- Experienced site supervisors Availability of experienced construction works in sors for community-based for drain construction, but no supervisors for community- vulnerable communities construction experience of community- based drain construction based construction Local construction practice Few (or no) construction good Construction guidelines Existing documents showing guidelines and documents practice documents available, but no distinction local good construction between good and poor practice construction practices Audit and accounting process Relatively immature account- Experience with accounting Transparent accounting and ing and auditing process for and auditing for community auditing processes that community contracting contracting, but no processes encourage good construction for encouraging good practice (e.g., linking disburse- construction practice ments to contractors to approval of completed works) Project safeguards Documented safeguards need Documents exist for some Documented safeguards to be located; no previous safeguards available from all relevant experience in interpreting and agencies operating safeguard policies CAPACITY LEVEL HOW TO ADAPT THE BLUEPRINT 1: Use this chapter The MCU needs to strengthen its resources prior to allowing construction to proceed. This might involve in depth and as a the following: catalyst to secure • Hiring experienced site supervisors from the commercial sector support from other agencies as • Using best practice documentation in this book to supplement available information that might be appropriate available regionally • Developing a suitable accounting and auditing policy, including a payment schedule, that is sufficiently resolved to the community contractor level rewards good practice • Approaching all relevant agencies to acquire their safeguard documents and distill them into a coherent working document for community-based contracting and construction 2: Some elements The MCU has strength in some areas, but not all. Elements that are perceived to be Level 1 need to be of this chapter will addressed as above. Elements that are Level 2 will need to be strengthened, such as the following: reflect current • If there is limited supervision experience, a senior supervisor could be recruited practice; read the remaining • If relevant safeguard documents are available but not collated, the MCU should systematically integrate elements in depth them into the implementation process and use them to • If the local audit process is insufficiently resolved, the process should be refined to incorporate features further strengthen such as contractor final withholding payments to encourage quality construction capacity 3: Use this chapter The MCU is likely to be able to proceed using existing proven capacity. It would be good practice, as a checklist nonetheless for the MCU to document relevant prior experience in community-based construction and related safeguards. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 6 7 A work package should have the following forms the basis for the specification of the characteristics (based on Wideman 2012): works in the work package RFT documents and contracts. • Have a defined size and duration, limited to To create work package RFT documents, relatively short periods of time the information from a bill of quantities is • Be able to be realistically estimated in terms combined with detailed construction specifi- of quantities and costs of works cations (a specified bill of quantities), and terms and conditions for construction. Con- • Produce measurable outputs (deliverables) tractors use these specified quantity estimates • Entail a large enough scope of work that and associated construction activities to price could be competitively bid for and con- the work for which they are bidding. tracted for by itself (the test of reasonable- Estimate quantities ness) The final drainage plan includes an estimate of • Be distinguishable from, but integrate with, the total project cost based on approximate other work packages. drain lengths and the number of houses for Work packages should be prepared by an roof water and gray water capture (chapter 6). engineer or quantity surveyor who is part of To create a detailed bill of quantities, the the landslide assessment and engineering or drainage plan needs to be further broken down technical task team, or who has been appointed into appropriate component parts (units) for by the MCU for this task. construction. The engineer or quantity surveyor should Measure and record the lengths of each use this section to guide the preparation of type of new drain section, culvert, and repairs work packages and request for tender (RFT) to existing drains (distinguished by drain documents—preparing a bill of quantities, size, design, and construction specifications), identifying work packages, and preparing and itemize drain components such as debris detailed construction design requirements traps. for each work package. This process should To obtain a bill of quantities for the capture be undertaken in accordance with the cho- of household roof and gray water, complete a sen form of construction procurement and detailed survey of each house selected in the community contracting for the project, drainage design phase (section 6.6). This task which affects the size (value) of contracts; should be performed by a surveyor or some- the tendering process; and roles/responsi- one familiar with the MoSSaiC methodology bilities of the government, community, and to ensure that proper connections are made contractors. between houses and existing or proposed drains. Table 7.2 lists the main items to include 7.3.1 Prepare a bill of quantities in the survey of each house. Ideally, the sur- The bill of quantities is a document containing veyor should also sketch a plan view of each an itemized breakdown of the quantity and house and mark details such as where the roof costs of materials, parts, and labor required for might need preparation for the works (fig- a construction project. Costs are estimated ure 7.3); the length of guttering; and the loca- based on approximate local costs for deliver- tions of downpipes, water tanks, and drain ing a unit of a certain type of work, such as connections. constructing a meter of reinforced concrete Obtain accurate estimates of all the compo- block drain. nents needed for roof water management, The bill of quantities serves two purposes— including brackets, connectors, and other fix- it provides a detailed breakdown of project ings (figures  7.4 and 7.5). Underestimation of costs for the MCU (against which the project quantities can result in work delays and loss of budget and progress can be managed), and project momentum (figure 7.6). 2 6 8    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S TAB L E 7.2  Items to include when surveying houses identified for household water capture COMPONENT ITEM DISCUSS WITH HOUSEHOLD, MEASURE, AND RECORD Preparation of Galvanized roofing Time allowances for trimming irregular galvanized roofing roof Replacement joists Lengths of joists to be repaired or replaced to allow fitting of facia boards and guttering Facia boards Lengths of facia board to be repaired or replaced prior to affixing roof guttering Roof water Guttering and • Lengths required capture downpipes • Estimated number of connectors and brackets to support gutters and downpipes during heavy rainfall events. • Where downpipes will be located in order to connect with water-tanks and drains • Connections to existing rainwater drums or tanks, and make the necessary provision for overflow into the nearest drain Water tanks (if • Water tank locations allocated to this house) • Connections to downpipes • How overflows will be connected to drains Gray water Pipes from kitchen and Length of piping required to capture gray water from kitchen capture bathroom sinks, washing machines, bathroom washbasins, and showers Drain Pipes and connection Confirm form of connection, quantity of parts, and location connections chambers or small (ensure that connections are of sufficient gradient to drains maximize flow rates) Hurricane Roof to top plate Ideally, enough straps should be included to allow the roofing strapping connections material to be attached at every joist Develop a spreadsheet with a page for every FI G U R E 7. 3  Modifications to roof structure for roof guttering installation house to detail the quantities of each item required (figure 7.7); include a master sheet that sums the quantities for all the houses. Add a contingency (usually 10 percent) to allow for unforeseen additional works or costs. F IGUR E 7.4  Downpipe installation detail CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 69 F IG U R E 7. 5  Roof guttering and downpipe F IGUR E 7. 6  Connection of downpipe to components drain awaits purchase of a connecting section FI G U R E 7.7  Spreadsheet to assist in developing bills of quantities Household name Fill in cells colored blue Household number Task Item Item cost Quantity No.lengths Remainder Total Cost Fascia board replacement 1"x8"x12' fascia board ft 0 0 ft 0.00 2"x6"x14' rafter ft 0 0 ft 0.00 2"x6"x16' rafter ft 0 0 ft 0.00 2"x6"x18' rafter ft 0 0 ft 0.00 2"x6"x20' rafter ft 0 0 ft 0.00 hurricane strap items - - 0.00 Install guttering 6"x13' guttering ft 0 0 ft 0.00 support bracket items - - 0.00 joint bracket items - - 0.00 stop end items - - 0.00 angle (D/M & PF angle) items - - 0.00 Connect guttering to downpipe running outlet items - - 0.00 112° bend items - - 0.00 92° bend items - - 0.00 6"x13' down pipe ft 0 0 ft 0.00 down pipe clips items - - 0.00 down pipe connector items - - 0.00 shoe items - - 0.00 Connect downpipe to drain connection pipes ft 0 0 ft 0.00 Connect wastewater to drain 1.5" elbow connector items - - 0.00 General 1lb bag screws items - - 0.00 rawl plugs items - - 0.00 Total 0.00 2 70    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S Confirm quantities and update the plan • Cost of materials per meter of drain (con- sider relevant construction methods, mate- The detailed drain alignments, the houses to rials, and drain dimensions) be connected, and the location of pipes and • Cost of roof guttering, pipes, water tanks, connection chambers should be confirmed and hurricane straps (include all fittings, with householders and all other relevant screws, nails, etc., and materials such as stakeholders (figure 7.8). Update the approved facia boards for repairing roofs) drainage plan with these details. The inven- tory of items needed to connect each house • Cost of transporting materials to the site (if should be appended to the plan as a separate there is no access by road, materials may document. The combined document, consist- need to be double handled—carried to a ing of the approved plan and the complete storage point and then again to the site) quantity schedule, is the definitive working • Cost of labor document to use in generating work packages. 7.3.2 Define work packages Use realistic unit costs Government ministries that regularly under- The MCU should determine the most appro- take or contract out construction works will priate contract size and structure for the cho- often have a standard list of unit costs. The sen community contracting process. In some unit costs selected by the engineer or quantity cases, work packages can be relatively small so surveyor for a MoSSaiC project should be that as many community-based contractors as adjusted appropriately to account for antici- possible can be awarded contracts for the pated fluctuations in the cost of construction works. For typical interventions in the Eastern materials and on-site conditions (such as poor Caribbean, contracts have been let for con- access by road), and to ensure that there is struction of approximately 100 m of reinforced profit for the community contractor. concrete block drains. Similarly, the installa- Particular unit costs relevant to MoSSaiC tion of household roof water and gray water interventions may include the following: connections and related items may be split into work packages involving approximately 20–30 houses. FI G U R E 7.8  Confirming with residents connection of households to drains Creating a large number of small work packages can maximize the number of com- munity residents (serving as contractors and laborers) benefiting from the short-term employment opportunity, but this approach creates a higher administrative and supervi- sory burden than if a smaller number of higher- value contracts were awarded. Balancing the larger number/lower-value work package option against smaller number/ higher-value work packages needs careful evaluation. In the former case, the provision of adequate on-site supervision for a large num- ber of contractors, perhaps all starting on the same day, poses a major demand on supervi- sory staff. However, engaging larger numbers of community contractors can help create a very positive atmosphere that encourages postproject maintenance and behavioral CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 7 1 changes with regard to surface water manage- ing agency, or individual appointed by the ment at the household scale. MCU; a construction committee formed by the Comply with relevant government or fund- community; or individual contractors from ing agency regulations regarding the value and within the community. In the latter two cases, issuance of contracts. In certain circum- the MCU may have oversight of procurement stances, regulations may permit contracts through the approval of contractors’ accounts below a certain value to be fast tracked through and verification on the ground of both material the tendering process. Designing work pack- delivery and construction. ages that fall below that value maximizes the It is important that the process for procur- number of contracts to be awarded (if this is ing materials meets project funder require- considered manageable and appropriate) and ments while remaining community based. It minimizes project lead times—an important should balance the need for upward account- performance indicator for community-based ability to donors and downward accountability construction projects (table 7.1). to those for whom the project is intended. 7.3.3 Prepare a plan for procurement of 7.3.4 Prepare detailed construction materials specifications The project engineer or quantity surveyor For each work package, list the relevant con- should develop a plan for procuring materials struction specifications and include any for construction based on the bill of quantities appropriate design drawings. Use table 7.3 as a and the form of community contracting being guide for preparing construction specifica- used. This plan should include the following tions for typical drainage components and information: refer to the examples of drain design drawings • For project management and RFT docu- in section 6.8.3. ments: These specifications should be used to inform potential contractors of the details of —— Required standards for products and the construction work required, and thus services guide the bids they submit; they should also —— Approved local suppliers form part of the terms of reference for work package contracts. —— Purchasing procedures and responsibili- ties 7.3.5 Compile documents for each work package • For project management and discussion with contractors once contracts are The following documents should be prepared awarded: and included in the RFT for each work pack- age; upon award, these documents will be —— Recommended unit costs issued to the contractors as part of their con- —— Anticipated transportation and storage tracts: costs and requirements • Description of the scope of work required —— Recommended schedules for delivery and contract duration ( just in time/daily/weekly) • Quantity estimates and a detailed descrip- —— Monitoring and security of materials on tion of associated construction activities site (based on the specified bill of quantities, sec- tion 7.3.1); note that cost estimates should not Depending on community capacity and proj- be provided to potential contractors ect procurement requirements, the responsibil- ity for procurement of materials may lie with a • The final drainage plan and the location of government task team member, an implement- the work package (section 7.3.2) 2 7 2    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S TAB L E 7. 3  Requirements and specifications to be developed for work packages CONSTRUCTION COMPONENT SPECIFICATION RATIONALE Dimensions Correct drain capacity, sidewalls flush with slope surface to allow inflow of surface water Reinforced Depth of excavation Strong foundations and prevention of concrete block undermining drains Reinforcement spacing Strength of structure, preventing leaks and Cement mix maximizing drain lifetime Finishing Locations and design of stepped Correct flow velocity (therefore correct sections capacity), prevention of stagnant water Downslope drains Location and height of upstands Prevent overflow (raised drain walls) Gradient Sufficient to ensure flow and prevent Intercept drains stagnant water Weep holes on upslope wall of drain Allow inflow to drain Debris trap locations Prevent blockage Covered sections and grills Allow pedestrian access to houses All drains Culvert design and gradient Sufficient gradient/capacity, self-cleaning to prevent blockage Location of connections Allow drains/pipes to connect Concrete Dimensions Sufficient capacity and gradient for flow to connection Inflow and outflow pipes drain chambers Covering/debris traps Prevent blockage Design of minor soil retaining Ancillary retaining structures Appropriate additional protection of slopes, structures Design of gabions drains, and ravines from erosion or landslides Design of rip-rap in natural channels Roof guttering Access to roofs Allow safe access for installation Specification of how all required Provide assurance that safeguards are Safeguards safeguards are of be met complied with, and thus that proposed design/construction can proceed • Requirements for procurement of materi- withholding of payment until poor work is als, parts, and labor (section 7.3.3); note that corrected) depending on the form of community con- • Annexes to the terms of the contract relat- tracting, contractors may not be responsi- ing to safeguards (such as procurement ble for procuring materials procedures, environmental requirements • Construction specifications and design for soil disposal, landownership issues, etc.) drawings (section 7.3.4) • Annexes to the terms of the contract relat- • Guidance relating to good and bad con- struction practices (sections 7.5, 7.6, and 7.7) ing to the financing schedule (advances/ mobilization sum, contingencies, final pay- • Instructions to bidders on how to submit a ment upon satisfactory completion, or tender CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 73 7.4 THE TENDERING PROCESS F IGUR E 7.9  On-site meetings with potential community contractors A typical community contracting tendering process involves three main activities: solicit- ing potential contractors and requesting that they tender for the works, providing guidance on how to submit tenders, and evaluating ten- ders and awarding contracts. This process, and the roles and responsibilities of those evaluat- ing and awarding contracts, must be clearly defined, publicly transparent, and fair. 7.4.1 Identifying contractors from the On-site meetings with potential community contractors can help convey good practice, community encourage inexperienced contractors to It is important to have a clear, comprehensive, participate, and share local knowledge relevant to construction practice or site well-advertised, and transparent process for details. soliciting potential community contractors and inviting them to tender. Sources of names of potential contractors with formal bidding processes and require- include the following: ments. • Residents approaching government task teams for work during mapping and drain- On-site briefing age design stages • Word of mouth within the community For each work package, potential contractors should be shown the following on site: • Community meetings • Where proposed drains start and finish, • Lists of community contractors previously drain dimensions and form of construction, engaged by government agencies. how they will connect to other drains, the specific construction requirements (exca- 7.4.2 Briefing potential contractors vation issues, weep holes, stepped falls, cul- Invite potential contractors to a project brief- verts, access to properties, etc.) ing led by the person or team that drew up the work packages and the person in charge of the • Which houses are to have roof water and gray water connections to main drains, how tendering process. There could be several they are to be connected, and any ancillary components to the briefing: construction requirements (e.g., hurricane • On-site briefing—a comprehensive walk- straps, water tanks, water tank overflow through of the proposed works on site in pipes). the community (figure 7.9) While on site, encourage potential contrac- • Detailed briefing—explaining the specific tors to consider the following: terms of the RFT documents and contracts, the process by which tenders will be evalu- • How materials will be transported to the ated and contracts awarded, and how con- site and where they will be delivered (fig- tracts will be managed ure 7.10a) • Assistance and guidance—given to contrac- • If double handling of materials will be nec- tors wishing to submit bids but unfamiliar essary 2 74    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S • Where materials will be stored (on site and • Where soil from excavation will be taken off site if necessary) • How roofs will be accessed for installation • Where cement will be mixed and water of guttering obtained (figure 7.10b); this location should • Any issues that might have been overlooked provide access to an adequate water supply, in the work package specifications storage space, and reasonable proximity to both material delivery and construction • Any local best practices and experience that sites, while not interrupting preexisting could be incorporated into the work pack- pathways residents would be expected to age specifications. use regularly Detailed briefing • Where fabrication of construction compo- nents will take place (shaping of reinforce- Inform contractors of the following: ment, construction of formwork, etc.) • The process by which tenders should be submitted, and how contracts will be awarded FI G U R E 7.1 0  Some issues to address during • The form of contract that will be issued on-site briefing • The inclusion of a contingency sum (often 10  percent), against which authorization for expenditure would be given separately in a written variation order • The procedure for materials procurement • The terms for final payment and require- ment for completion of works to a satisfac- tory standard • The withholding of payments if works are unsatisfactory • Any other contract terms specific to gov- ernment practice or funding agency requirements; for instance, if double han- dling and storage of materials are required, conditions relating to agreed-on proce- a. Consider how materials will be transported dures for storage site selection may need to on site. be included in the contracts (figure 7.11) Assistance and guidance Attempt to gauge the level of support needed to enable contractors to submit bids. Support may be necessary when contractors • have limited experience with formal con- tracting, • are unfamiliar with the relevant terminol- b. Plan where cement mixing can take place. ogy, CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 75 compounded by the fact that the institutional F IG U R E 7.1 1  Double handling of materials framework that supports the construction can require temporary storage industry in the majority of developing coun- tries is very weak and underdeveloped. For the above reasons, the project procure- ment plan may allow the disbursement of start-up (mobilization) funds to contractors. Additionally, contractors may wish to assist each other by pooling resources for common tasks such as purchasing materials and pay- ing for laborers to manually transport materi- als on site. Contractor collaboration is a potentially powerful process in facilitating capacity building among community mem- bers in project initiation, delivery, and imple- mentation. If the procurement of materials is to be the responsibility of the contractors (rather than an agency or individual appointed by the MCU, or a community construction committee) guidance should be provided on cost and price structures. In preparing tenders, potential • need help in completing the required ten- contractors will need to consider the price der documents, they are likely to pay for materials and there- • require assistance in interpreting an fore likely costs for construction work (Ogun- awarded contract, or lana and Butt 2000). Cost estimates should also account for potential fluctuations in mate- • are not able to read or write. rial prices due to factors such as material shortages, charges for transportation to the Assess the level of assistance needed during site, or changes in supplier (typically, some 60 the contractor briefing process. The process of percent of construction materials are imported offering assistance and guidance should be in the developing world—Nordberg 1999) Ide- transparent, open to all potential contractors, ally, the contractor needs to have an integrated and without breaching any contracting and view of the relationship between estimating, procurement protocols. The process should tendering, budgeting, and cost control. avoid the perception that one contractor is being favored over another. 7.4.3 Evaluating tenders and awarding While there can be many benefits in using contracts small-scale community-based contractors, The process for evaluating tenders and small contracting enterprises have certain lim- awarding contracts will vary from project to itations such as their ability to obtain credit project depending on government and fund- and financial resources (Larcher 1999). In ing agency requirements, the form of com- many cases, a contractor’s size and turnover munity contracting chosen, and the value (or may be below the level required for achieving size) of the contracts. In most cases, submit- a credit rating, thus preventing access to loans ted tenders will be evaluated by a tenders for construction mobilization (i.e., procuring board on the basis of proposed costs and the materials and employing laborers at the start technical skill or expertise of the contractors. of construction, before receiving any pay- The evaluation may also take into account ments for completed works). This is often wider project objectives such as building 2 76    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S local capacity and providing short-term employment. For small projects or urgent F IGUR E 7.12  Contractor signing on site with implementing agency representative works, contracts can often be awarded to nominated contractors as single-source (no bid) contracts, providing approval is received from the funding agency. 7.4.4 Contractors and safeguard policies Throughout the processes leading to contract award (figure 7.12), the MCU and all the asso- ciated MoSSaiC teams should be aware of all relevant safeguards, including those detailed in table  7.4 (see also 1.5.3 and 7.10.4). These safeguards are included for guidance only; dif- ferent countries, funding agencies, and legal systems can be expected to have other or dif- fering requirements. The MCU should agree on a mechanism for communicating safe- guards to contractors, which should be rein- forced by the site supervisor. TAB L E 7.4  Illustrative safeguard checklist for contractors WHAT CONTRACTOR SAFEGUARD ILLUSTRATIVE TRIGGER SHOULD DO Natural • Is there the potential to cause significant conversion (loss) Alert the site supervisor habitats or degradation of natural habitats? Disputed • Is the project situated in a disputed area? Seek assurance from the areas • Has landownership been established and permission government task team granted in writing if required? Involuntary • Are the works likely to lead not only to physical relocation, Avoid these issues resettlement but to any loss of land or other assets resulting in the during construction following: • Relocation or loss of shelter • Loss of assets or access to assets • Loss of income sources or means of livelihood, regardless of whether affected people must move to another location Questionable • Contractor’s claim for costs beyond the common labor cost Ensure honest submis- (corrupt) raise and inflation rates sions are always made practices • Materials and equipment used and workmanship not as specified; paperwork not consistent with items delivered • Contractors providing false information to project inspec- tors on progress of work or inspectors being coerced to approve progress payments or certify conformance with building permits • Inaccurate as-built drawings being presented or accepted Source: http://go.worldbank.org/WTA1ODE7T0. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 7 7 7.5 IMPLEMENTING THE WORKS: • contractors are unlikely to have been in ON-SITE REQUIREMENTS regular work and may need technical assistance and advice from site supervi- 7.5.1 Importance of site supervision sors, • laborers are likely to have been unemployed Experienced, trained site supervisors should for a considerable time or may only have oversee implementation of the works, provid- limited construction experience, ing technical advice for contractors, interpret- ing the construction design specifications on • a large number of people are likely to be site, and ensuring good-quality construction. employed simultaneously as work com- Good supervisors can help identify and mences, and address problems such as a lack of skills among • residents often request additional works to contractors and laborers, unclear construction be undertaken once works have com- design specifications, incorrect choice of con- menced. struction methods and equipment, and diffi- cult site conditions. Use the following sections as a prompt for The quality of site supervision has a major training site supervisors for MoSSaiC projects influence on the overall performance and and as a guide to implementing the drainage efficiency of construction projects. Inade- works. quate supervision is believed to be one of the major causes of rework. Therefore, experi- Selecting the site supervisor enced and well-trained supervisors have an The site supervisor should be experienced in important role in minimising the amount of rework due to construction defects (Alwi, the technical aspects of drainage construction Hampson, and Mohamed 1999, 1). and the supervision of small contracts. If pos- sible, he or she will also have worked with Data on the inverse relationship between informal contractors in vulnerable urban com- the costs of poor-quality construction (rework) munities. and funds spent on training (percentage of Ideally, the supervisor will have been total project cost) demonstrate that training of involved in the community-based mapping site supervisors and contractors is cost-effec- and drainage design process. This involve- tive (figure 7.13). ment will help ensure that the supervisor is Trained site supervisors should be used for conversant with the rationale for the landslide community-based construction projects such hazard reduction and drainage plan, which is as MoSSaiC in which useful for two reasons: • Adjustments or adaptations of construction details are likely to be required during the F IG U R E 7.1 3  Importance of training in reducing rework costs course of construction (figure 7.14), and these will need to take into account the 3.5 slope processes and contribute to reducing the landslide hazard. % rework costs 3.0 2.5 • During construction, the supervisor will probably be the most regular point of con- 2.0 tact between the community and govern- ment task teams and the MCU. The super- 1.5 0.6 0.8 1.0 1.2 1.4 visor should be willing and able to answer % training costs residents’ questions and resolve minor Source: Alwi, Hampson, and Mohamed 1999. issues related to the works (such as ensur- ing access to houses during construction). 2 78    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S FI G U R E 7.1 4  Clear markings help remove F IGUR E 7.15  Site supervisor is critical to issues of ambiguity for site supervisor project success and to ensuring good construction practice Spraying paint marker positions on the ground helps ensures clarity of alignment details. The site supervisor should make daily visits to the site during the initial stages of construc- Meeting with the community before the start tion to address the following: of construction • Resolve any ambiguity contractors may From their involvement in the slope feature have in establishing drain alignments mapping and discussions concerning the draft and final drainage plans, the community • Resolve any unforeseen issues with resi- should already be aware of the timetable for dents commencement of the drainage works. Once a • Demonstrate a hands-on approach, which site supervisor has been appointed, it is good will help build trust among contractors and practice for that individual to meet on site community residents alike with community residents in both formal and informal contexts. The supervisor can explain • Set a standard of engagement for those details of the timing of the construction and working for the contractors, who are likely other issues that may concern residents, such to have been unemployed for some time as materials storage and temporary access to and in need of clear guidance properties during construction. • Be alerted early on to any potential contin- The MCU should make known to commu- gency drawdown nity residents who the primary point of con- tact will be during construction—often this • Ensure that contractors only employ the will be the site supervisor. Supervisor-com- number of laborers required; the project’s munity contact is an important element in start-up might attract a large number of securing continued, positive community residents, some of whom are not employed engagement (figure 7.15). on the project but might wish to be so (fig- ure 7.16). Supervising construction start The contractors should be informed of the 7.5.2 Beginning construction: Excavation proposed site supervision program: who the and alignment requirements supervisor will be, how to contact the supervi- sor, and how often the supervisor will be on During the initial phase of drain excavation site. It should be stressed to the contractors and construction, the following design and and supervisor that construction quality is construction details will need to be deter- critical to the overall performance of the inter- mined on site in the context of the work pack- vention in reducing landslide hazard. age contract and the ground conditions. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 79 • Smoothing the alignment of bends or junc- F IG U R E 7.1 6  Supervision issue: Large tions in the drain; these should not be numbers of residents engaging with sharply angled or water will overshoot or contractors damage the drain, and there should be suf- ficient depth and width to accommodate increased flows • Incorporating asymmetry of the ground slope conditions in drain cross-sections; reinforcement and drain side walls will need to be adapted (for example, figure 7.17 shows higher reinforcement on the upslope side of the intercept drain) F IGUR E 7.17   Example of detailed alignment issue encountered at construction Construction commencement location start Construction of a drain should typically com- mence at the planned furthermost downslope location of the drain. Starting excavation and construction at the highest elevation of a drain may concentrate and direct water to those areas of the hillside lacking drains, thus increasing the potential for soil erosion and landslides. Heavy rainfall can also overdeepen the already excavated drain routes, resulting in the need for more materials (to construct larger drains commensurate in size with the newly eroded and overdeepened trench), or excessive backfilling of completed drains (which can create preferential subsurface flow paths and erosion alongside the drains). Detailed alignment issues Supervisors and contractors will likely have to make minor adjustments to drain alignments, Channel gradient issues excavation, and preparation of reinforcement or formwork according to detailed site and In the context of the work package specifica- ground conditions. tions and the above issues related to drain Minor on-site adjustments to the drainage alignment, the supervisor and contractors will design may involve the following: need to make on-site judgments as to the appropriate depth and gradient of excavation, • Removing or avoiding obstacles to drain and the detailed locations of any required excavation, such as tree roots and boulders drain steps. Drain channel gradients should • Adjusting the alignment according to minor ensure sufficient flow velocity, especially topographic variations that would other- through culverts, and limit the build-up of wise affect drain gradient and flow capac- debris; but should not be so steep as to cause ity; this is especially relevant with intercept overtopping, erosion of the drain, and flooding drains designed to run cross-slope further downslope. 2 8 0    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S Specific on-site requirements relating to Drain wall drain channel gradient include the following: Construct the top of drain side walls flush with • Creating steps in the drains with steep the ground surface (on both sides of downslope channel gradients to slow flow velocity drains and on the upslope side of intercept especially where the drain changes direc- drains) (figure  7.19). This construction detail tion or where two drains join (steps reduce needs to be stressed to residents and contrac- the risk of overtopping due to excess flow tors. Where there is inadequate design and site velocity) supervision, it is not uncommon for sidewalls to be constructed above ground level, thereby • Making intercept and downslope drains preventing surface water from entering the self-cleaning by establishing drain channel drain. gradients that maintain adequate flow velocity and thus reduce the deposition of Incorporate weep holes debris (figure 7.18) Weep holes allow water to enter drains by cap- • Ensuring that finished invert levels will turing subsurface (infiltrated) water from the prevent standing water or an incorrect flow uppermost soil horizons. Weep holes on the direction upslope sidewall of an intercept drain are 7.5.3 Ensure that water can enter drains especially important. If they are excluded, subsurface flow may, as a consequence, pass Casting of the base of the drains and construc- under the drain base and erode drain founda- tion of block work side walls is a critical phase tions on the downslope side. of drain construction. If construction is too Discuss weep hole provision with the con- hasty or poorly supervised, the result can be an tractor since the spacing of vertical reinforce- ineffective drain that fails to capture surface ment rods needs to be accommodated at the runoff—and therefore to reduce landslide haz- start of drain construction. ard. Ineffective drain construction can be Weep holes can be formed in several ways, avoided by the contractor adhering to the fol- the most common of which are by leaving gaps lowing construction guidance. in block construction (figure 7.20a), using a FI G U R E 7.1 8  Self-cleaning stepped drains Ensuring stepped drains that self-clean is a vital element of good practice and needs to be carefully supervised on site because ground conditions may not always make that easy to achieve. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 8 1 F IG U R E 7.1 9  Finished drain wall height F IGUR E 7. 2 1  Drain construction providing same as adjoining ground surface for eventual connection with gray water pipes When the finished drain height is the same as that of the adjoining ground surface, water can enter the drain from the side slopes. Here, the drain walls are the correct height, and surface water will be able to enter the drain once the backfill has been added and compacted. Inexperienced contractors often construct drain side walls to a finished level above that of the ground surface. half block (figure 7.20b), and inserting plastic can result in concentrated discharge from piping (figure 7.20c). unconnected downpipes, kitchens, and bath- rooms, eroding the soil, damaging unfinished Construct drains before installing roof guttering drains, and potentially increasing local flood- and house connections ing or landslide hazards. If household water (gray water and roof water) is to be connected to the drain via pipes or 7.5.4 Capture household roof water minor household drains, make provision for Prepare and repair roofs these connections during construction (fig- ure 7.21). A careful and comprehensive survey of any Install roof guttering after drains are com- required roof work should have been under- pleted. Installation prior to drain construction taken during preparation of the bill of quanti- FI G U R E 7.20  Weep hole formation a. Weep holes should be incorporated in b. Weep hole formed by a half block c. Weep hole formed by small plastic concrete block drain construction on the laid orthogonal to the drain wall. pipe. upslope side, to allow the capture of subsurface flow. 2 82    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S ties and the work packages (sections 7.3.1 and nection to water tanks, drains, or concrete 7.3.2). Omission of these details from the sched- chambers with piped connections to drains. ule of works can result in cost overruns, poten- Once the downpipe locations have been tial difficulty in acquiring additional materials, determined, install the roof guttering so that and delays in completion of the works. water will flow along the guttering to the Carry out minor roof repairs and prepara- downpipes with sufficient velocity to prevent tions (figure 7.22a and b) such as the following: overtopping during major rainfall events. Brackets and other fittings should be aligned • Repairing or replacing facia boards and the to ensure flow in the correct direction (fig- ends of joists ure 7.23). • Trimming galvanized roof sheets to ensure that the roof guttering is able to capture all the roof water F IGUR E 7. 2 3  Newly installed roof • Reattaching galvanized sheeting to joists guttering where fixings have been lost. It may be decided that it is impractical or uneconomical to repair certain roof structures within the constraints of the project budget (figure 7.22c). If such a decision is reached, the reasons for not installing roof guttering need to be discussed with the resident(s) concerned and with the community more widely, in the context of the agreed project and budget pri- orities. Roof guttering may require the reversal of Install roof guttering existing guttering to create flow directions that are efficient for downpipe and main drain Attach roof guttering to sound facia boards. connections. Identify downpipe locations that allow con- FI G U R E 7. 2 2  Issues involved in roof repair c. Some roof structures may require complete replacement. The decision to undertake such extensive works needs to be carefully assessed in terms of community and government expecta- tions regarding levels of household support being provided. a and b. Make minor roof repairs to allow the installation of guttering, downpipes, and hurricane straps. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 8 3 7.5.5 Connect household water to drains ure 7.24). It is good practice to do the follow- ing: Each house receiving roof guttering and gray • Bury connection pipes wherever possible to water connections must be connected to the prevent damage. drainage network. Potential connection options should have been identified during the • Securely attach connection pipes to the drainage design process (section 6.6.4) such as drain wall at the pipe discharge point to direct pipe connections, connection by pipe to prevent potential disconnection during a concrete chamber and then by pipe to the times of high flow rates. drain, or construction of a small drain to con- Construct concrete chambers for connecting nect to the main drain. drainage pipes All household guttering and piped connec- tions to drains need to be watertight. Supervi- Concrete connection chambers should be con- sors should inspect roof guttering, downpipes, structed when the roof guttering is installed to and all other pipes during and after rainfall to ensure that the planned locations are viable ensure that they are performing properly and with respect to the final location of downpipes. are securely fitted. It is not usually difficult to Connection chamber location, design, and remedy small problems. If left untreated, how- construction should ever, loose connections can leak, damage walls • ensure a sufficient gradient on the pipe out- and foundations, and result in erosion and fall to the drain for self-cleaning; flooding. • incorporate as large an outflow pipe as pos- Direct connections sible, or use two smaller pipes to ensure suf- In some cases, downpipes and gray water ficient capacity; pipes can be connected directly to drains (fig- F IG U R E 7. 24  Household roof water connections to main drains Care needs to be taken to ensure that household roof water connections to main drains are sufficiently rigid and deliver rapid flow rates to encourage self-cleaning. 2 8 4    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S • incorporate a cover or debris trap to mini- 7.6.1 Cast concrete in good weather mize blockages and enable cleaning; and The base of the drain should be cast in good • be carefully finished with a skim of cement weather, allowing sufficient time for the con- to prevent leakage (figure 7.25). crete to set before there is a flow in the par- Install water tank overflows tially constructed drain. Rainwater discharge over a drain base that has not set can easily Whether the resident already collects rain- erode the mix and waste valuable materials water, or a new water tank is being provided and construction time (figure 7.27). as part of the project, an overflow pipe needs • Estimate the time needed for excavation, to be fitted to the tank and connected to a preparation, material delivery, and carrying drain (figure 7.26). The routing of the over- materials to the site. flow can dictate tank location and therefore which downpipe is best connected to the • Use these estimates to break up the required tank. works into tasks that can be managed real- istically and completed each day, in accor- dance with weather conditions. 7.6 IMPLEMENTING THE WORKS: • Anticipate the possibility of overnight rain- GOOD PRACTICES fall. The following guidelines provide examples of • Take high temperatures into account; con- good practices beyond the construction crete can set too quickly and crack if it is not requirements previously outlined. properly shaded and kept damp. FI G U R E 7.25  Concrete connection chambers Concrete connection chambers are an efficient way of collecting roof water in high-density housing areas. When finished, pipes should be covered over to prevent them from causing an obstruction, and chambers should be fitted with a removable cover. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 8 5 F IG U R E 7. 2 6  Connecting water tank overflow pipes to nearby drains Rainwater harvesting to water tanks should be accompanied by the provision of an overflow to a nearby main drain. F IG U R E 7. 2 7  Examples of drain bases a. A well-constructed drain base cast in good b. Erosion of a newly cast drain base: reinforce- weather conditions. ment is exposed and water may eventually break though the base. 2 8 6    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S 7.6.2 Store materials securely • Keep records of all materials purchased, such as open bills, receipts, and delivery Identify a secure on-site location for storing records. materials and minimizing the risk of theft. • Ensure that material is sent from the storage • Time the purchase and delivery of materi- location to the site only when it is needed. als to coincide with planned construction • Ensure that materials released can be used tasks so that there is not too much material within the working day; this reduces the on site at any one time; be sure to take pos- likelihood of theft. sible delays in delivery into account. • Coordinate with residents to find a trusted 7.6.4 Provide access for residents individual who can store the materials Excavation and construction of drains can lead securely, for example, at a shop, community to temporary problems with access to paths center, house, or backyard. and houses. Contractors need to keep the • Use a locked container if there is no suitably goodwill of residents and be sensitive to any secure alternative. unavoidable disruption caused. • Store materials in more public areas if they • Create temporary access for residents when will be used within the working day. drains are being constructed (figure 7.28). • If the final design has not made provision 7.6.3 Keep an inventory for access across a drain, consider using contingency funds to construct a step over Inventory control by those in charge of pro- the drain. curement and by contractors helps prevent theft, and is useful in resolving potential dis- • Because extensive sections of covered drain putes between and among residents, laborers, will not capture surface flows and may and contractors regarding material usage. become blocked with debris, limit covered FI G U R E 7.28  Providing adequate temporary access to houses during construction CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 8 7 sections only to what is necessary for can be difficult to rectify (both politically and access. financially), this section identifies drainage design details and related construction prac- 7.6.5 Minimize leakage from pipes tices that should be avoided. Ensure that roof guttering, downpipes, and all Getting drainage design and construction piped connections to drains are watertight to details correct helps prevent unnecessary avoid damaging houses and creating concen- additional construction costs due to wasted trated flows that could increase localized soil materials or the need for rework, ensures that erosion, flood, or landslide hazards. Be aware drains function as intended, and can improve of the locations of existing drainage or water the physical environment for residents (e.g., by supply pipes to avoid causing damage during reducing localized flooding, deposition of construction. eroded materials and debris, standing water, and waterlogged soils). Site inspections in • Ensure drainage pipe connections are Hong Kong SAR, China (reported by Hui, Sun, watertight (figure 7.29). and Ho 2007), highlight some examples of • Check for leaks in existing water supply inadequate attention given to surface drainage and gray water pipes and household stop design and construction details construction taps. details (table 7.5). Figure 7.30 illustrates several such drainage problems commonly found in • Ensure that excavation and construction do unauthorized communities not cause new leaks in existing pipes. • Ask the water company to reroute pipes 7.7.1 Wasted materials and no surface that cross the proposed alignment of new water capture drains. Contractors may perceive drain sidewall con- struction design to be similar to that of small soil-retaining structures, thus incorrectly F IG U R E 7. 2 9   Using sleeving to join building above the level of the slope surface drainage pipe sections and preventing surface water runoff from entering the drain. Stress to contractors that drain sidewalls must be flush with ground level to capture hillslope surface flow along its length. Contractors should avoid building drain block work above ground level since this • wastes materials; • renders the drain largely ineffective in cap- turing surface water; and • can result in flow occurring along the out- side of the drain, causing flooding 7.7 IMPLEMENTING THE WORKS: downslope while potentially undermining PRACTICES TO BE AVOIDED the drain (figure 7.31). 7.7.2 Restricted capacity of footpath The desire for community workers to be paid drains quickly, together with poor site supervision, can sometimes lead to poor construction. The flow capacity of drains adjacent to steps in Steps should be taken at the outset to avoid a footpath is determined by the point of mini- such circumstances. Since poor construction mum drain depth in line with the back of the 2 8 8    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S TAB L E 7.5  Examples of frequently overlooked drainage design and construction details DETAIL DESCRIPTION Sharp bends Presence of sharp bends in drainage channels with no baffle walls provided to control potential splashing Inadequate capacity Inadequate capacity of downstream drainage provisions to cater to discharge from the slope (e.g., large channels discharging into smaller- sized channels), hence resulting in overflow Wrong fall Drainage channels with an as-built fall in a direction opposite design intent Obstructions in drain Presence of obstructions in drainage channels leading to reduction in drainage capacity Sidewalls too high Inadequate construction of drainage channels with the tops of sidewalls being above the adjacent ground level, leading to erosion along the side of the channel Lack of upstands Lack of upstands at the downhill side of road/pavement to minimize the chance of uncontrolled discharge of surface runoff to the downhill slope at low points or vulnerable locations Lack of intersecting drains Lack of intersecting drains along a long sloping road/pavement, which may act as a conduit to reduce accumulated discharge at certain points down the road/pavement and avoid surface erosion or flooding Channels constructed close to Drainage channels constructed close to mature trees necessitate mature trees removal of some tree roots, with the attendant risk of adverse impact on tree health as well as possible damage to the channels by tree root action in due course Undersized drainage channels Undersized drainage channels that can lead to splashing, overflow, and hence erosion of the slope surface alongside the drainage channels No debris/silt traps Absence of trash grill or debris/silt traps at inlets to main culverts/ drainage channels, making them vulnerable to blockage, especially where the site setting involves major surface runoff during heavy rainfall leading to scouring and washout debris in the upstream/uphill area Poor debris/silt trap design Inappropriate detailing of trash grill/debris screens at drainage inlets, which are liable to lead to turbulent flow and splashing Inadequate protection of Inadequate protection of headwalls at inlets to cross-road culverts cross road culverts headwalls against water ingress into the road embankment leading to wetting of the ground and potential subsurface erosion and ground movement (hence possible cracking of the culverts and consequential leakage which can affect the downhill slope) Insufficient downslope Inadequate number of drainage discharge points provided drainage points Undersized connection Undersized drain connection chambers can be prone to blockage chambers Poor footpath/drain design Presence of a concrete stairway adjoining drainage channel that is liable to act as an interceptor and prevent surface runoff from getting into the channel Poor connecting drain design Poor detailing at the connection between existing drainage provision and the new slope drainage systems Absence of intercept drains Absence of intercept drains or inadequate sizing of intercept drains for slopes with sizeable surface catchments Source: Hui, Sun, and Ho 2007. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 8 9 FI G U R E 7. 3 0  Illustrations of frequently overlooked drainage design and construction details natural drainage obstructed UPV pipe sharp obstructing drain bend channel too inadequate close to tree drain backfill capacity not compacted household water wrong fall drain side wall discharged onto too high hillside drain undermined surface water not and cracked no drainage at back captured by drain of retaining wall water flow along footpath uncontrolled discharge onto hillside pipe obstructing uncontrolled drain discharge onto road no debris trap inadequate culvert capacity Source: Hui, Sun, and Ho 2007. Reproduced with permission of the Head of the Geotechnical Engineering Office and the Director of the Civil Engineering Department, Hong Kong SAR, China. footpath tread. Once this flow depth is F IG U R E 7. 31  Drain built with exceeded, water will flow onto the steps and inappropriately high sidewalls down the footpath. Typically, footpath drain capacity is less than 50 percent of perceived capacity (figure 7.32). Footpath drains should be designed and constructed to account for the tread depth of footpath steps where this is feasible; other- wise, depth compensation must be made such that the minimum drain depth is considered adequate. This design detail is significant in heavy rainfall, and can make the difference between High sidewalls prevent inflow and encourage a safe footpath and one swamped with so flow alongside and under the drain. Drain finished height should be in line with that of much water it is too hazardous to use. the adjacent ground surface. 2 9 0    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S 7.7.4 Construction detailing notes FI G U R E 7. 32  Identify maximum drain capacity adjacent to footpath steps Site supervision and final construction detail- ing are important in achieving landslide haz- ard reduction. The MCU should consider pro- viding contractors and supervisors with copies of sections 7.6 and 7.7, incorporating additional local good practices as applicable. 7.8 SIGNING OFF ON THE COMPLETED WORKS This capacity may be less than it first appears and result in water overtopping the drain and The landslide assessment and engineering flowing down footpath steps. task team and/or engineer appointed by the MCU should ensure that each work package is completed satisfactorily before works are signed off on and final payments made to con- 7.7.3 Hazardous access for residents tractors. This process involves confirming that During and after drain construction, residents there are no works outstanding from the con- may be affected by access issues where new tract and there are no construction defects. drains cross footpaths. Although it is good Minor additional works may also be identified practice to provide steps or grills over drains, beyond the scope of the original contract. these should be carefully designed so as not to Construction defects could include the fol- cause a further hazard: lowing: • Grills where a path passes over a drain can • Unauthorized deviations from the design or be a hazard to young children unless the construction specification spacing of the bars is sufficiently small (fig- • Use of substandard materials ure 7.33). • Where concrete slabs are used to bridge • Poor workmanship drains for access, they should be textured to • Problems with the original design and spec- prevent the surface from becoming slippery ification of the works. during heavy rain. Site supervisors should advise the engineer of any issues during construction such as the need for minor changes in drain alignment or FI G U R E 7. 33  Some construction practices can pose dangers to small children design due to conditions on site. Community residents should also be given the opportunity to comment on the works and suggest small additions that may reasonably be required, such as access across drains. Outstanding works and defects due to con- tractor error should be corrected before final payment. However, contractors should not be penalized for deficiencies in the original design and construction specification. Rather, additional works required due to redesign or unforeseen works should be agreed upon with CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 9 1 contractors and paid for using the contingency 7.9 POSTCONSTRUCTION sum, or a further single-source contract issued. BIOENGINEERING The engineer and site supervisor should prepare a schedule of construction defects and outstanding works for each work package and Although MoSSaiC is focused on appropriate identify remedial actions required for comple- surface water drainage to reduce landslide tion; table 7.6 provides an example template. hazard, other related interventions and prac- Additional works may also be specified and a tices such as bioengineering can potentially payment schedule agreed upon. Discuss this add value (Anderson 1983; Florineth, Rauch, schedule on site with contractors and agree on and Staffler 2002; Howell 1999a; Lewis, Salis- a time frame for completion. Provide copies of bury, and Hagen 2001; Stokes et al. 2007). the this schedule to the contractor, site super- While specific plants can sometimes increase visor, engineer, and community leaders. the strength of slope materials, a particular Once the works are completed, the con- benefit of bioengineering is in reducing slope struction is signed off on by the authorized erosion. Erosion is the detachment and trans- engineer, and final payments are released to port of material particles by rainfall and flow- contractors. ing water (or other agents), and involves a dif- ferent set of physical processes from those MILESTONE 7: associated with slope stability (as defined in chapter 3). In some communities, residents Sign-off on completed erroneously regard erosion as synonymous construction with landslides. It can be appropriate to dis- cuss these two slope processes with residents, TA BLE 7. 6  Example of an informal schedule of construction defects and outstanding works CONSTRUCTION DEFECTS, OUTSTANDING WORKS, AND REQUIRED REMEDIAL WORKS COMMUNITY: DATE: REPORTING TECHNICIAN/ENGINEER: CONTRACTOR: LOCATION DESCRIPTION OF PROBLEM AND DESIGN (NUMBER ON PLAN) REFERENCE NUMBER OF PHOTO RATIONALE AND PRIORITY DRAWING 12 Complete connection of main Prevention of flooding of i drain to footpath drain above existing landslide area bakery 18 Complete drain by House 15: link Essential to avoid flooding of ii drains above and below already Property 16 constructed; 30 m reinforced concrete block drain required Install house downpipe connec- Essential to prevent erosion 23 iii tions to main drains of path 27 Realign drain to ensure reverse Site instructions given May 21 iv flow of drain into existing ravine 30 Install concrete slab over drain to Additional works identified v provide access to Houses 2 and 7 by community and approved by authorized project engineer 2 92    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S and explain that appropriate slope vegetation management can help reduce both erosion and F IGUR E 7. 3 4  Typical development of plant communities under a bioengineering and maintenance program landslide hazard. Reducing soil erosion can also assist in reducing the amount of debris deposited in drains during heavy rainfall events. A. At the end of the first This section provides a short introduction growing season, planted grasses to bioengineering and how it can be part of have established throughout the site, with shrubs and trees good slope management practice in communi- growing at regular intervals. ties. A discussion with a local plant or forestry specialist would assist the landslide assess- ment and engineering task team in reviewing B. After five growing seasons, the potential for supplementing the drainage the shrubs and trees have intervention with bioengineering where hous- developed a full canopy and shaded out the grasses ing density permits. underneath. Erosion is now possible on the unprotected 7.9.1 What is bioengineering? surface. Bioengineering is commonly defined as the use of any form of vegetation as an engineering C. After pruning and thinning, the grasses have regrown. This is material (i.e., one that has quantifiable charac- now an ideal plant community teristics and behavior). Bioengineering mea- for engineering purposes. Large trees are rooting deeply, but sures use two distinct components: living have been pollarded so their components (live species), and nonliving or weight does not surcharge the structural components such as dead stakes, slope. Grasses provide a dense surface cover to prevent erosion. cribwalls, and timber. These two component types may be used alone or in combination Source: Howell 1999a. (Campbell et al. 2008). Soil bioengineering applications require careful planning, since both engineering • Uptake of soil water by roots reduces the practices and ecological principles need to water content of the slope material and be applied. Most natural plant communities therefore reduces pore water pressures. do not have the desired engineering proper- ties for slope stabilization or surface erosion • Vegetation intercepts rainfall, thus reduc- protection because species have not evolved ing surface water infiltration. specifically for those purposes (Howell 1999a); this underscores the importance of • By intercepting rainfall and reducing sur- careful planning. An ideal plant community face water runoff, vegetation can reduce configuration has to be both engineered and soil erosion. maintained as the vegetation grows (fig- In some cases, vegetation can act to reduce ure 7.34). the stability of a slope by the following mecha- 7.9.2 The effect vegetation on slope nisms: stability • Large trees increase slope loading. Some plants can have a significant role in sta- • Trees are subject to “wind throw,” which bilizing and protecting slopes. Plant roots can exerts a force on the slope during high reinforce the slope by adding tensile strength winds. and anchoring slope materials (figure 7.35). In terms of slope hydrology, there are three main • Stem flow and live or decaying roots can positive hydrological effects: generate preferential flow paths into and CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   2 93 that do not provide adequate stabilization or F IG U R E 7. 35  Lateral root spread surface protection. When considering bioengineering to sup- plement a MoSSaiC drainage intervention, talk to community residents about local vege- tation management practices, the removal of vegetation from slopes, whether they grow subsistence crops or crops to sell, and the ben- efits and disadvantages of different planting schemes. Involve local plant experts and engi- neers in identifying plants that have a positive effect on slope stability and provide protection from soil erosion. Refer to studies and guidance notes on bio- engineering to inform the discussion on the most appropriate planting scheme for the community. Comprehensive processes for selecting bioengineering approaches are given by Howell (1999b; see table 7.7) and Campbell The extent of lateral root spread in this red et al. (2008); major reviews of bioengineering cedar can help reinforce upper soil layers; species with a larger tap root would reinforce practice can be found in Barker (1995), Camp- the slope at depth. bell et al. (2008), Coppin and Richards (1990), and Gray and Sotir (1996); Wilkinson et al. (2002) provide modeling evidence of slope types for which vegetation increases or within slope material (macropores), decreases landslide risk. It is beyond the scope increasing the concentration of water in of this book to provide species information or certain locations. specific planting guidance, as local climatic • Some cultivated species, such as banana conditions will play a significant role in this and plantain, contribute to slope loading regard. while developing only very limited root sys- In many cases, grasses and shrubs may pro- tems. vide a good bioengineering solution for com- munities. Some grass species, such as vetiver, There are acknowledged limitations to bio- have extensive root networks and can provide engineering. Campbell et al. (2008, 13) sum- both soil strength and surface protection. They marize these: “although the benefits of vegeta- can also trap loose slope material and reduce tion to prevent soil erosion are well established, sedimentation in surface drains. Grasses need its ability to stabilise slopes subject to shallow significant sunlight to become established and failures is less well proven, and certainly less will not easily survive in a community of other well quantified.” plants, so any shrubs and trees should be kept thinned and pruned for the grasses to continue 7.9.3 Vegetation and urban slope to thrive. Because long grass can provide an management ideal environment for insects, rats, and other In areas of unauthorized housing, vegetation is pests in urban areas, due care and consider- commonly removed for house construction, ation are needed in planning their use in any potentially increasing landslide hazard and community bioengineering intervention. soil erosion. The slope may subsequently be Figure 7.36 illustrates different vegetation kept clear of vegetation or planted with crops covers for four slopes. Vegetation manage- 2 9 4    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S TAB L E 7.7  Decision aid for choosing a bioengineering technique START PREVIOUS/ SLOPE SLOPE MATERIAL SITE POTENTIAL FUNCTION ANGLE LENGTH DRAINAGE MOISTURE PROBLEM REQUIRED TECHNIQUE Armor, reinforce, Damp Erosion, slumping Diagonal grass lines Good drain Dry Erosion Armor, reinforce Contour grass lines 1. Downslope grass lines & vegetated stone pitched > 15 m Drain, armor, Damp Slumping, erosion rills or reinforce Poor 2. Chevron grass lines and vegetated stone pitched rills Armor, reinforce, Dry Erosion, slumping Diagonal grass lines > 45° drain 1. Diagonal grass lines or Good Any Erosion Armor, reinforce 2. Jute netting and randomly planted grass Drain, armor, 1. Downslope grass lines or Damp Slumping, erosion < 15 m reinforce 2. Diagonal grass lines Poor 1. Jute netting and randomly planted grass or Armor, reinforce, Dry Erosion, slumping 2. Contour grass lines or drain 3. Diagonal grass lines 1. Horizontal bolster cylinders & shrub/tree planting or Armor, reinforce, Good Any Erosion 2. Downslope grass lines & vegetated stone pitched rills or catch > 15 m 3. Site grass seeding, mulch & wide mesh jute netting Drain, armor, 1. Herringbone bolster cylinder & shrub/tree planting or Poor Any Slumping, erosion reinforce 2. Another drainage system and shrub/tree planting 1. Brush layers of woody cuttings or 2. Contour grass lines or Armor, reinforce, 30°–45° Good Any Erosion 3. Contour fascines or catch 4. Palisades of woody cuttings or 5. Site grass seeding, mulch & wide mesh jute netting < 15 m 1. Diagonal grass lines or 2. Diagonal brush layers or Drain, armor, Poor Any Slumping, erosion 3. Herringbone fascines and shrub/tree planting or reinforce 4. Herringbone bolster cylinders & shrub/tree planting or 5. Another drainage system and shrub/tree planting 1. Site seeding of grass and shrub/tree planting or Good Any Erosion Armor, catch 2. Shrub/tree planting Any Drain, armor, 1. Diagonal lines of grass and shrubs/trees or Poor Any Slumping, erosion < 30° catch 2. Shrub/tree planting < 15 m Any Erosion Armor, catch Turfing and shrub/tree planting Planar sliding or Support, anchor, 1. Large bamboo planting or Base of any slope shear failure catch 2. Large tree planting SPECIAL CONDITIONS Planar sliding, shear Site seeding of shrubs/small treesb Anya Anya Anya Anya Reinforce, anchor failure > 30° Any Any rocky material Debris fall Reinforce, anchor Site seeding of shrubs/small trees Any loose sand Good Any Erosion Armor Jute netting and randomly planted grass Any rato mato Poor Any Erosion, slumping Armor, drain Diagonal lines of grass and shrubs/trees 1. Large bamboo planting or Armor, reinforce, Gullies ≤ 45° Any gully Erosion (major) 2. Live check dams or catch 3. Vegetated stone pitching Source: Howell 1999b. Note: “Any rocky material” is defined as material into which rooted plants cannot be planted, but seeds can be inserted in holes made with a steel bar. “Any loose sand” is defined as any slope in a weak, unconsolidated sandy material. Such materials are normally river deposits of recent geological origin. “Any rato mato” is defined as a red soil with a high clay content. It is normally of clay loam texture, and formed from prolonged weathering. It can be considered semilateritic. Techniques in bold type are preferred. a. Possible overlap with parameters described in the rows above. b. May be required in combination with other techniques listed in the rows above. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 9 5 FI G U R E 7. 3 6  Four vegetation covers typically found on hillsides housing vulnerable communities Slopes with acceptable vegetation cover from a slope stability Slopes for which bioengineering improvements could be perspective considered in order to reduce landslide risk a. Low-density housing with b. Vegetation comprising c. Natural vegetation cleared d. Marginally stable slope minimum disturbance to the mostly grasses and medium and crops grown on a with essentially no vegeta- slope. Care needs to be shrubs on a shallow slope previously failed slope tion. This slope would taken to ensure maintenance with minor slope failures. (dasheen, indicating damp benefit from grass and shrub of this mixed cover, should conditions). Care needs to be planting to assist landslide other houses be built. taken that more mature risk reduction. vegetation is not removed, drainage is adequate, and surface cover is maintained. ment, especially on slopes similar to those F IGUR E 7. 37  Bioengineered slope in Hong shown in c and d of figure 7.36, can help limit Kong SAR, China the amount of rain and surface water infiltrat- ing the hillslope, thereby reducing landslide risk. Figure 7.37 illustrates sound bioengineer- ing practice on a steep slope in the absence of housing structures; the grasses exhibit an excellent water shedding quality, which helps maintain slope stability. 2 9 6    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S 7.10 RESOURCES 7.10.1 Who does what CHAPTER TEAM RESPONSIBILITY ACTIONS AND HELPFUL HINTS SECTION Confirm community contracting • Define and facilitate an appropriate contracting approach in 7.2 approach for implementation of the accordance with funder/government procurement requirements drainage works and government/community capacity • Define and facilitate the tendering process 7.3; 7.4; 7.8 Ensure that processes for procure- • Identify appropriate work package size (value) ment of works and materials and standards for construction meet • Authorize an engineer and/or quantity surveyor to prepare work funder/government requirements package specifications and be responsible for signing off on MCU completed works • Select a committed site supervisor 7.5.1 Ensure that adequate site supervision Helpful hint: This is a pivotal role in construction quality, so choose processes are in place a committed person is likely to be respected by contractors and community/government task team members. Coordinate with government task teams • Prepare a specified bill of quantities for the planned works and a 7.3 plan for procurement of materials Prepare work packages • Identify work packages according to contract size and number agreed with the MCU • Create RFT documents Issue RFTs and brief potential • Hold briefing meeting with potential contractors and provide 7.4.1; 7.4.2 contractors on required works, good guidance and assistance with tendering process practices, and safeguards Facilitate the tender evaluation and • Adhere to tendering procedures, ensuring transparency 7.4.3 contract award in accordance with Helpful hint: Typically, more contractors will want work than can be selected community contracting employed. Try to ensure that the contracting process is as positive approach as possible for all potential contractors. Government task teams Facilitate site supervision and • Provide training for site supervisors 7.5; 7.6; 7.7 communication among community • Ensure day-to-day presence of supervisor on site to deliver residents, contractors, and good-quality works government task teams Coordinate with community task teams • Ensure comprehensive snagging is recorded and completed prior 7.8 to sign-off Helpful hint: Spend time on site with government task team Sign off on completed construction members and key residents to ensure, as far as possible, that all snagging is identified and competed. Once the project has been closed, contractor remobilization even for small tasks can be time consuming. Coordinate with the MCU and • Participate in agreed-upon community contracting process 7.2 government task teams on the community contracting process Understand the planned works, good • Attend briefing by government task teams on scope of work 7.4 construction practices, appropriate packages, good construction practices, and safeguards safeguards, and tender for works • Submit tenders for work packages • Construct drains and install household roof water and gray water 7.5; 7.6; 7.7 connections Community task teams • Adhere to site supervision and good practice guidelines Implement contracted works Helpful hint: Avoid material waste (and consequent income loss) by following design specifications and not overconstructing—seek advice from the site supervisor on details that require on-site design decisions. Complete construction to required • Address construction defects and complete any outstanding works 7.8 specifications to the satisfaction of the authorized project engineer Coordinate with government task teams CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 9 7 7.10.2 Chapter checklist SIGN- CHAPTER CHECK THAT: TEAM PERSON OFF SECTION 99A specified bill of quantities and a plan for procurement of materials have 7.2; 7.3.3 been completed 99A specified bill of quantities and a plan for procurement of materials have 7.3 been completed 99Work packages and request for tender documents have been drawn up and 7.3.5; 7.4 potential contractors briefed on how to tender 99Contract details include construction specifications and design drawings, and 7.3 adequate provision for mobilization and contingencies 99A site supervisor has been selected and trained, and contractors briefed on 7.5; 7.6; 7.7 good construction practice 99A schedule of construction defects and outstanding works has been drawn up 7.8 and acted on 99Milestone 7: Sign-off on completed construction 7.8 1.5.3; 2.3.2, 99All necessary safeguards complied with 7.10.4 7.10.3 Low-cost appropriate construction F IGUR E 7. 3 8  Choosing a debris trap methods location Debris trap construction The following method can be used to con- struct a low-cost debris trap suitable for instal- lation in modest-sized, well-maintained drains in vulnerable communities. 1. Choose a location for the debris trap that can be easily accessed for debris removal (figure 7.38). 2. Acquire reinforcing rods, an angle iron, and all necessary welding equipment. 3. Mark the location and angle of the trap against the drain side walls; measure and cut the angle iron on which the trap grill will rest. 4. Drill holes in the drain sidewalls to place reinforcing rods that will support the angle iron. 6. Position all vertical reinforcement bars and weld in position (figure 7.39). Weld the 5. Cut the reinforcing rods to fit the depth of handle so the finished trap can be easily the holes and the angle iron width. Cut removed by sliding up the angle iron; this vertical and horizontal reinforcement bars will make it easier to maintain the drain to length. not just upstream of the trap, but also in the culvert under the footpath as necessary. 2 9 8    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S —— 16-gauge mesh (the drain shoulder FI G U R E 7. 39  Welding in-situ and should be approximately 50 cm wide) completion of debris trap —— Sunlight-stable polythene (200 micron or equivalent; allow for sufficient over- lap of sheets) —— 10 m measuring tape —— Sand for sand blinding (if necessary) —— Galvanized wire to tie mesh sections together —— Reinforcing rods to create U-shaped clamps 2. Excavate drain trench and shoulders. 3. Where the base of the drain is on a combi- nation of stony material and soil, sand blind the drain base. 4. Estimate the length and width of plastic How to construct a low-cost drain and mesh required. Installing low-cost drains that use appropriate 5. Sand blind the drain shoulder where nec- local materials can engage the community in essary. developing good slope management practices 6. Cut the mesh to the overall drain width. and provide hands-on training for supervisors, contractors, and laborers. 7. Starting at the downslope end of the drain Contractors and residents can use the fol- and working upslope, position and mold lowing method (figure 7.40) to construct a sim- the mesh to the drain and then remove. ple low-cost drain in locations with low drain discharges and flow velocities, such as in the 8. Lay plastic lining in the drain starting at following circumstances: the lowest elevation and working upslope (so sheets overlap and shed water without • For connecting small numbers of houses to leaking) (figure 7.40b). main drains 9. Overlay the plastic with the mesh (fig- • In less accessible locations, such as upper ure 7.40c). slopes, where materials for concrete drains cannot be transported or carried 10. Anchor the plastic and the mesh on the drain shoulders with appropriate nails­­­ • On unstable slope sections that need sur- (e.g., ~30 cm long U-shaped clamps made face drainage, but where slope movement from reinforcing rods). may be reactivated 11. Tie the mesh sections together with galva- 1. Assemble materials and tools: nized wire (figure 7.40d). —— Pickaxes, shovels, and a wheelbarrow 12. Make steps in the drain where appropriate for excavating the drain trench (figure 7.40e). —— Scissors to cut polythene 13. Connect house waste pipes to the finished —— Wire cutters to cut mesh drain. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    2 9 9 FI G U R E 7.40  Construction of low-cost drain a. Community leaders, residents, local b. Laying plastic lining on sand blinded c. Overlaying with galvanized mesh. contractors, and site supervisors assemble base. on site to begin construction of a low-cost drain. d. Tying mesh lengths with galvanized e. Forming a step down in the drain. f. Finishing the drain with a cement skim wire. on the drain base. 14. Modify the drain design as required or as • Information leaked to a private owner or materials allow; this might include lining buyer about land needed for a public project the drain with a skim of cement (fig- • Projects approved without proper permits ure 7.40f ). or designs 7.10.4 Questionable or corrupt practices • Projects prepared for bidding without com- in construction ment by the public or responsible local offi- cials The MCU, and all stakeholders involved in construction, should apply relevant project • Project specifications that limit the number safeguards (such as those in section 1.5.3), and of bidders avoid questionable or corrupt practices includ- • Deviation from standard bidding documents ing the following (World Bank 2010). • Direct contracting of bids without proper Planning and prebid justification • Inflated cost estimates, including for land • Restricted advertising, insufficient notice, purchases and/or inadequate time for preparing bids 3 0 0    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S • Advance release of bid information to one • Delayed or superficial evaluation; delayed bidder publication of evaluation report • Bids accepted after the submission deadline • Failure to disqualify companies impugned in evaluation reports Contract award and project implementation 7.10.5 References • Bid evaluation committee has conflict-of- interest ties with bidders Alwi, S., K. Hampson, and S. Mohamed. 1999. “Investigation into the Relationship between • Amending evaluation criteria after receipt Rework and Site Supervision in High Rise of bids Building Construction in Indonesia.” In Proceedings of the 2nd International Conference • Company presenting competing bids on Construction Process Reengineering, 189–95. July, Sydney. http://eprints.qut.edu. • Government allowing bid evaluation report au/4161/1/4161_1.pdf. to be revised or reissued Anderson, M. G. 1983. “The Prediction of Soil • Government imposing subcontracting Suction for Slopes in Hong Kong.” CE3/81, requirements on prime contractor Geotechnical Control Office, Hong Kong Government. • Staff members involved in contract award Barker, D. H., ed. 1995. Vegetation and Slopes: participating in contract supervision Stabilisation, Protection and Ecology. London: Thomas Telford Publishing. • Contract variations and change orders approved without proper verification Campbell, S. D. G., R. Shaw, R. J. Sewell, and J. C. F. Wong. 2008. “Guidelines for Soil • Contractor claims for costs beyond the Bioengineering Applications on Natural Terrain common labor cost raise and inflation rates Landslide Scars.” GEO Report 227, Geotechnical Engineering Office, Government of Hong Kong • Materials and equipment used and work- Special Administrative Region. manship not as specified; paperwork not Coppin, N. J., and I. G. Richards. 1990. Use of consistent with items delivered Vegetation in Civil Engineering. London: CIRIA/ Butterworths. • Contractors providing false information to project inspectors on progress of work, or de Silva, S., 2000. Community-Based Contracting: A Review of Stakeholder Experience. Washington, inspectors coerced to approve progress DC: World Bank. payments or certify compliance with build- ing permits Florineth, F., H. P. Rauch, and H. P. Staffler. 2002. “Stabilization of Landslides with Bio- • Inaccurate as-built drawings presented or Engineering Measures in South Tyrol/Italy and accepted Thankot/Nepal.” In INTERPRAEVENT 2002 in the Pacific Rim, 2002, Matsumoto/Japan, vol. 2, Monitoring 827–37. Matsumoto, Japan. • Staff responsible for oversight have con- Gray, D. H., and R. B. Sotir. 1996. Biotechnical and Bioengineering Slope Stabilisation: A Practical flicts of interest Guide for Erosion Control. New York: Wiley. • Control systems are inadequate, unreliable, Howell, J. 1999a. “Roadside Bio-Engineering— or inconsistently applied Reference Manual.” Department of Roads, Government of Nepal. • No follow-up undertaken regarding indica- tions, suspicion, or accusations of corrup- Howell, J. 1999b. “Roadside Bio-Engineering—Site Handbook.” Department of Roads, Government tion of Nepal. • Lack of confidentiality on accusations of Hui, T. H. H., H. W. Sun, and K. K. S. Ho. 2007. corruption “Review of Slope Surface Drainage with CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 0 1 Reference to Landslide Studies and Current Engineers—Engineering Sustainability 157(4): Practice.” GEO Report 210, Geotechnical 193 –201. Engineering Office, Government of Hong Kong Stokes, A., J. Spanos, J. E. Norris, and E. Special Administrative Region. Cammeratt, eds. 2007. Eco- and Ground Larcher, P. 1999. “Construction: Is There a Place for Bio-Engineering: The Use of Vegetation to Small-Scale Contracting Enterprises?” Urban Improve Slope Stability. Proceedings of the First Forum 10: 75–89. International Conference on Eco-Engineering. Lewis, L., S. L. Salisbury, and S. Hagen. 2001. “Soil Developments in Plant and Soil Science vol. 103. Bioengineering for Upland Slope Dordrecht, the Netherlands: Springer. http:// Stabilization.” Washington State www.springerlink.com/content/978-1-4020- Transportation Center, University of 5592-8/#section=291629&page=1. Washington. http://www.wsdot.wa.gov/eesc/ Wideman, M. 2012. “Project Management of cae/design/roadside/rm.htm. Capital Projects—An Overview.” http://www. Nordberg, R. 1999. “Building Sustainable Cities.” maxwideman.com/papers/capitalprojects/ International Union for Housing Finance. breakdown.htm. http://www.housingfinance.org/publications/ Wilkinson, P. L., M. G. Anderson, D. M. Lloyd, and others-publications. J. P. Renaud. 2002. “Landslide Hazard and Ogunlana, S. O., and K. Butt. 2000. “Construction Bioengineering: Towards Providing Improved Project Cost Feedback in Developing Decision Support through Integrated Model Economies: The Case of Pakistan.” http://www. Development.” Environmental Modelling and irb.fraunhofer.de/CIBlibrary/search-quick- Software 7: 333–44. result-list.jsp?A&idSuche=CIB+DC8938. World Bank. 2010. Safer Homes, Stronger Sohail, M., and A. N. Baldwin. 2004. “Community- Communities. A Handbook for Reconstructing Partnered Contracts in Developing Countries.” after Natural Disasters. Washington, DC: World Proceedings of the Institution of Civil Bank. 3 02    C H A P T E R 7.   I M P L E M E N T I N G T H E P L A N N E D W O R K S “…people are generally not well prepared to interpret low probabilities when reaching decisions about unlikely events… People underestimate both the probability of a disaster and the accompanying losses.” —H. Kunreuther and M. Useem, “Principles and Challenges for Reducing Risks from Disasters” (2010, 6–7) CHAPTER 8 Encouraging Behavioral Change 8.1 KEY CHAPTER ELEMENTS 8.1.1 Coverage This chapter presents communication and Stability in Communities) landslide hazard capacity-building strategies for achieving behav- reduction practice and policy. The listed groups ioral change in MoSSaiC (Management of Slope should read the indicated chapter sections. AUDIENCE CHAPTER F M G C LEARNING SECTION   Steps involved in behavioral change 8.3   How learning by doing can build capacity 8.3    Ways to communicate 8.4; 8.5    Ways of building local capacity 8.6    Postproject maintenance options 8.7.1     Mapping the behavioral change strategy 8.7.2 F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors 8.1.2 Documents CHAPTER DOCUMENT TO BE PRODUCED SECTION Communication strategy 8.5 Capacity-building strategy 8.6 Behavioral change strategy 8.7.2 305 8.1.3 Steps and outputs STEP OUTPUT 1. Understand how new practices are adopted Assessment of • Use the steps in the ladder of adoption and behavioral change model to aspects of identify communication and capacity-building needs in each community and behavioral change in government to be addressed by communication • Understand stakeholder perceptions and the role of community participation and capacity- building activities 2. Design a communication strategy Communication • Review existing resources and methodologies for designing a communication strategy strategy • Identify communication purposes and audiences • Select forms of communication and design messages 3. Design a capacity-building strategy Capacity-building • Review knowledge into action approaches strategy • Identify levels of capacity, capacity requirements, and activities for building capacity 4. Plan for postproject maintenance Project • Understand the need for incorporating maintenance into drain design and maintenance project planning options 5. Map out the complete behavioral change strategy Map of capacity- • Map the agreed-upon behavioral change strategies and associated actions building strategies 8.1.4 Community-based aspects cies. To achieve such behavioral change, MoSSaiC projects deliver landslide hazard The chapter outlines the process by which mitigation measures that are scientifically communities adopt new risk reduction behav- based, grounded in community participation, ior. It develops communication and capacity- and supported by ex ante landslide mitigation building strategies to encourage behavioral policies. change with respect to landslide hazard man- During project implementation, two com- agement practices in vulnerable urban com- plementary mechanisms can encourage com- munities. munities and governments to adopt effective The chapter also describes how MoSSaiC’s landslide risk reduction practices and policies: community-based approach encourages behav- the development of a clear and comprehensive ioral change in government task teams, the communication strategy, and the building of MoSSaiC core unit (MCU), and decision mak- local capacity. These mechanisms target ers as they gain new knowledge, build their behavioral changes, and should be developed capacity, and change practices and policies. and applied from the start of a MoSSaiC proj- ect. Communication strategy 8.2 GETTING STARTED A communication strategy is a well-planned 8.2.1 Briefing note series of actions aimed at achieving certain objectives through the use of communication A fundamental medium-term objective of methods, techniques, and approaches (FAO MoSSaiC is to change urban landslide risk 2004). Developing a communication strategy management perceptions, practices, and poli- entails clearly identifying (and segmenting) 3 0 6    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E audiences, defining messages, determining the 8.2.2 Guiding principles means of communication best suited to the local context, and integrating the strategy into The following guiding principles apply in the process of project implementation. encouraging behavioral change: Communication strategies for disaster risk • Recognize that it takes time and strategic reduction (DRR) may explicitly address risk implementation of MoSSaiC projects to perception and understanding in order to start to change the landslide risk reduction encourage a change in risk reduction behavior. behavior of communities and governments. However, “concern does not mean under- Behavioral change involves changing per- standing, and under­ standing does not neces- ceptions, motivations, capabilities, and sarily lead to action” (World Bank 2010). Com- actions to enable new practices to be munication strategies should thus be adopted. Communication and capacity- developed and applied in conjunction with building strategies are an important part of other behavioral change strategies such as the behavioral change process. community participation and empowerment (Paton 2003). In community participatory • Clearly communicate project messages to projects such as MoSSaiC, the communication set expectations about the project scope, strategy facilitates interaction among stake- process, and outputs. These messages holders and provides the common ground by should be backed up by timely project deliv- which project objectives can be achieved (Bes- ery to maintain trust among project stake- sette 2004). holders. Building capacity • Incorporate the communication strategy into the community participation process. DRR capacity building refers to actions that The MCU and the government task teams develop the skills and societal infrastructures should be aware of local social and cultural within communities or organizations to reduce conditions and how their interactions with the level of disaster risk. These actions include the community will be interpreted. training and education, public information, transferring technology or technical expertise, • Plan capacity-building activities that both strengthening infrastructure, and enhancing translate new knowledge into action and organizational abilities (UNISDR 2004). action into new knowledge (learning by Capacity building and communication doing). This second, less formal, aspect of overlap in their aim to increase knowledge and capacity building is a key part of MoSSaiC change behavior. However, as already noted, projects for communities and government DRR knowledge and technology do not auto- teams. matically translate into action or increased • Project messages and new capabilities for capacity (Paton 2003). Capacity building landslide risk reduction can be lost with should go beyond traditional approaches that government staff turnover. The MCU emphasize education and training in the class- should develop communication and capac- room, and include on-the-job learning and ity-building strategies for government task informal knowledge sharing (CADRI 2011). teams (as well as communities) to avoid MoSSaiC encourages a learning-by-doing project disruption due to staff turnover and approach to build the capacity of individuals, to sustain new capacities over the long communities, and governments to understand term. and address rainfall-triggered landslide haz- ards. Learning by doing enables community • Policy champions are important in keeping and government teams to develop new knowl- landslide hazard mitigation on the govern- edge, skills, and expertise as they implement ment agenda. This support can provide a the project. policy and funding environment for longer- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 0 7 term project continuity and behavioral answering such questions as “When is the change at both the community and govern- project going to start?” is key. ment levels. Relevant forms of communication and capacity 8.2.3 Risks and challenges building Risk perception In reaching community residents and the wider public with project messages, People generally underestimate the probabil- project managers should be wary of “one- ity of disasters, the associated risks, and the size-fits-all” solutions that appear to solve all accompanying losses. They also have a ten- problems by using media products. Past dency to estimate risks based on their own experience indicates that unless such instru- experience rather than on information con- ments are used in connection with other approaches and based on proper research, veyed by experts. One outcome is an overin- they seldom deliver the intended results vestment in prevention after a disaster has (Mefalopulos 2008, 20). occurred—prevention is then undertaken too late (Kunreuther and Useem 2010). Defining a Media such as TV, radio, newspaper articles, sound communication strategy therefore and static forms of awareness raising (posters, requires an understanding of people’s percep- leaflets, and displays) should thus be com- tions and behavioral biases. bined with personal contact and community participation in a way that is locally appropri- Clear project messages ate. Having a clear set of project messages for Similarly, DRR capacity-building activities stakeholders is essential. Community resi- should be case specific and adapted to local dents, government task teams, decision mak- conditions at three interrelated levels: individ- ers, funders, and the wider public will need to ual, organizational, and institutional/societal know about the MoSSaiC approach and proj- (the enabling environment) (CADRI 2011). For ect implementation process (such as project MoSSaiC projects, a combination of formal steps, time frames, roles and responsibilities, and informal activities should be designed to procurement, training, and maintenance) in equip individuals, communities, government varying levels of detail. task teams, and the MCU to deliver landslide Messages for each audience need to be hazard reduction measures. At the level of the developed and delivered ahead of the time societal/institutional enabling environment, they will be needed so that they influence, the aim should be to show that such measures rather than simply record, events. A lack of both work and pay so as to provide an evidence harmonized and clear communication may base for changing broader landslide risk mean projects exhibit poor coordination, reduction practices and policies. insufficient lesson learning, high rates of High staff turnover duplication, and poor integration with related projects in communities. While the MCU may interface with key gov- ernment officials and elected officials at the Timing of media reports time of project initiation, there is every pros- The local media can want a project news item pect that, through the project period, there before there is anything of substance to report. could be significant turnover among the staff Additionally, unless there is clear communica- responsible for project delivery and those sup- tion, expectations among those who pick up porting the project indirectly. Personnel on project news items could run ahead of proj- changes can result in loss of project owner- ect delivery. It is critical to ensure that reported ship, understanding, and capacity as well as timelines are as accurate as possible when potentially delaying project delivery. The communicating with the media; correctly MCU should develop clear project messages 3 0 8    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E and mechanisms for bringing new staff outcome should be reduced landslide hazard onboard and up to speed. (physical mitigation measures) and increased resilience to landslide risk (awareness and 8.2.4 Adapting the chapter blueprint to avoidance, or mitigation, of future landslide existing capacity hazards). Some specific aspects of behavior Successful communication and capacity- change associated with MoSSaiC follow. building strategies for landslide hazard reduc- • At the household level. Residents have tion do not follow an easily specified formula greater confidence in adapting how they but should be developed according to local build on, drain, bioengineer, and maintain conditions. Use the capacity guides from pre- their part of the hillside, dedicating money vious chapters (each relating to a MoSSaiC and time to appropriate landslide mitiga- project step) to identify the following: tion measures and slope management. • Critical points for communication among • At the community level. Communities rec- stakeholders during project implementa- ognize the importance of drain mainte- tion nance in reducing landslide risk, and act on • Areas that need capacity building in order that recognition by advocating for, and to deliver effective landslide hazard reduc- becoming involved in, a postproject main- tion measures. tenance strategy (section 8.7.1). • At the government level. Practitioners and Use the matrix on the next page to assess policy makers have a greater ability to existing capacity for delivering the necessary address small-scale everyday landslide haz- communication and capacity-building activi- ards, which reflect an accumulation of ties. disaster risk, and anticipate the capacity to 1. Assign a capacity score from 1 to 3 (low to deal with medium- and large-scale land- high) to reflect the existing capacity for slide events (Bull-Kamanga et al. 2003). each of the elements in the matrix’s left- Use this section to understand how people hand column. adopt new risk reduction behavior and how 2. Identify the most common capacity score as two crosscutting issues—risk perception and an indicator of the overall capacity level. the knowledge into action learning process— affect communication and capacity-building 3. Adapt the blueprint in this chapter in accor- strategies for behavioral change. dance with the overall capacity level (see guide on page 311). 8.3.1 The behavioral change process UNICEF (2008, 1) notes The global experience of the development 8.3 ADOPTION OF CHANGE: community has demonstrated that Commu- FROM RISK PERCEPTION TO nity-based Disaster Risk Reduction (CBDRR) BEHAVIORAL CHANGE efforts approached from a social and behav- iour change perspective ensure that the poorest, most vulnerable and marginalised MoSSaiC uses a combination of community communities understand the simple and and government teamwork, scientific meth- practical actions required to protect lives and ods, and the delivery of hazard reduction mea- personal assets in the case of natural disas- sures on the ground to reduce urban landslide ters. risk (chapters 2–7). If it is to be sustainable, landslide risk reduction needs to be embedded The process of adopting innovation (behav- in urban slope management practice and pol- ioral change) can be seen as a series of steps in icy by communities and governments. The a “ladder of adoption” (Mefalopulos and Kam- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 0 9 EXISTING CAPACITY CAPACITY ELEMENT 1 = LOW 2 = MODERATE 3 = HIGH MCU and government Behavioral change strategies Some success in behavioral Experience with successful understanding of the not considered in previous change by raising disaster risk DRR behavioral change using a behavioral change process community-based DRR awareness through media range of formal and informal with respect to DRR in projects campaigns and formal communication and capacity- communities classroom training courses building activities MCU and government Little experience with Small number of ad hoc Previous successful high- experience with community- community-based DRR community campaigns profile campaigns led by an based DRR awareness awareness campaigns on undertaken by different experienced government campaigns which to build government agencies agency or specialized team Community interaction with Little evidence of community Community residents willing Community residents available the media—persons willing interaction with the media to talk to the media but with who may have participated in and able to communicate little prior experience other community programs disaster risk problems and and would be willing to solutions to the wider public articulate the project vision Media relationship with No substantive media Government has previously Government uses professional government production houses; media outsourced a limited number media outlets that are functions on an ad hoc basis of media campaigns respected by the general public MCU and government No experience with commu- Some experience with formal Effective use of a range of experience in using different nity participation and and informal communications appropriate formal and forms of communication as associated forms of commu- with communities informal communications as part of the community nication an integral part of community participation process participation projects MCU and government No local venues suitable for Some MCU members have Well-frequented conference experience in delivering training government or participated in courses at venue for training that is known formal capacity-building community teams; very different venues; limited MCU to the MCU and community training courses (classroom- limited MCU experience in experience in course residents alike; MCU members based education, training course management and management have previously run and workshops, and conferences) delivery attended training courses MCU and community DRR capacity-building Some experience of, and Experience with successful experience of, and openness activities perceived to be openness to, delivering and informal capacity-building to, informal capacity-building based on formal knowledge participating in informal DRR approaches that have helped activities (on-the-job training, transfer (classroom-based capacity-building activities changed DRR perceptions, learning by doing) for DRR education and training) practices, and policies Engagement of policy champi- Senior government officials A senior government official One or more senior govern- ons for advocating communi- have an administrative rather has offered to support ment officials are active ty-based DRR policies than advocacy approach to community projects, but advocates of the MoSSaiC community projects perhaps not in an advocacy approach and support DRR sense policy change Project safeguards Documented safeguards need Documents exist for some Documented safeguards to be located; no previous safeguards available from all relevant experience in interpreting and agencies operating safeguard policies longera 2004; World Bank 2011). These generic in table 8.2. This model can be used to under- steps, and the associated MoSSaiC context, are stand capacities and gaps in the process of outlined in table 8.1. adoption of MoSSaiC by individuals, commu- Movement from awareness to adoption is nities, government teams, and decision makers. often explained in terms of factors affecting For example, a small number of successfully how people are motivated, form intentions, implemented MoSSaiC projects can encourage and then act to reduce the risk. These three decision makers to commit resources to more classes of behavior change factors are outlined projects and increase the outcome expectancy 3 1 0    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E CAPACITY LEVEL HOW TO ADAPT THE BLUEPRINT 1: Use this chapter The MCU needs to strengthen its capacity in order to deliver strategies that encourage behavioral change. in depth and as a This might involve the following: catalyst to secure • Spending considerable time in a community to find champions for the vision support from other agencies as • Advocating to the government and identifying a policy champion appropriate • Seeking advice from government public information agencies, local media consultants, and local nongovernmental organizations (NGOs) on effective forms of communication • Seeking advice from donors, NGOs, and government agencies on appropriate capacity-building strategies for both communities and government practitioners • Using MoSSaiC resources as a training platform adapted to local conditions 2: Some elements The MCU has strength in some areas, but not all. Those elements that are perceived to be Level 1 need to of this chapter will be addressed (as above). Elements that are Level 2 will require strengthening, such as the following: reflect current • Where there is limited experience of different forms of communication appropriate for community- practice; read the based DRR, seek advice from local media, NGOs, and relevant government agencies to identify culturally remaining elements relevant, acceptable, and effective forms of communication in depth and use them to further • Where there is limited experience of DRR capacity building within communities and government, strengthen capacity assemble examples of, and resources for, delivering both formal and informal activities 3: Use this chapter The MCU is likely to be able to proceed using existing proven capacity. It would be good practice as a checklist nonetheless for the MCU to document relevant prior experience in communications and capacity building for community-based DRR. of government teams and other communities; and outcome expectancy; community partici- while visits to finished projects and on-the-job pation and capacity-building activities may be training can increase self-efficacy. more effective in changing self-efficacy, prob- A combination of behavioral change strate- lem-focused coping, or trust (Paton 2003). gies is needed to facilitate change in all of these The MCU should use the ladder of adop- factors and encourage effective landslide risk tion and behavior change model to identify reduction. Communication and provision of strengths and gaps in the process of behavior information can help change risk perceptions change for each MoSSaiC stakeholder group. TAB L E 8 .1  Steps in the ladder of adoption and associated MoSSaiC context STEP IN THE LADDER OF ADOPTION MoSSaiC CONTEXT 1. Awareness of the problem • Risk perception and critical awareness of local landslide hazards, risks, and drivers 2. Interest in the specific problem • Personal interest in the idea that urban landslide hazard can often be reduced 3. Knowledge/comprehension of how to • Understanding of the MoSSaiC vision, science, and project process for urban change the situation landslide hazard reduction 4. Attitude affecting tendency to accept • Acceptance at the community level and adopt an innovation • Decision to accept, fund, and initiate the MoSSaiC approach in a particular country 5. Legitimization within local norms and • Adaptation of MoSSaiC at the community level (bottom up) as well as by funders context and within government (top down) 6. Practice putting knowledge into action • Delivery of landslide hazard reduction measures on the ground in communities before adopting 7. Adoption of new approach—behav- • Improved landslide hazard reduction and slope management practices within ioral change communities and government Source: Mefalopulos and Kamlongera 2004. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 1 1 TA BLE 8 . 2  Behavior change factors: From motivation to action PHASE FACTOR 1. Motivating Risk perception: What is the hazard, and does it pose a threat? factors (often Critical awareness of hazard: How much do I think/talk about the hazard compared collectively with other hazards? referred to as risk perception) Hazard anxiety: How much destruction and death can the hazard cause? (This can also be a demotivating factor, as people seek to reduce anxiety by ignoring the hazard.) 2. Intention Outcome expectancy: Will my actions be effective in reducing the problem? formation factors Self-efficacy: Do I have the capacity to act effectively? or beliefs Problem-focused coping: Will I try to confront this problem? Response efficacy: Are there enough resources (technical, financial, physical, social, and political) to allow me to confront this problem? 3. Moderating Timing of hazard activity: What is the frequency/predictability/interval since the factors affecting last event? conversion of Sense of community; perceived responsibility: What are people’s attachments to intentions into places and other people? actions Response efficacy: What is the actual availability of resources? Normative beliefs within a community: What are the community experiences, perceptions, beliefs, trust in authorities, degree of participation/empowerment? Source: Paton 2003. 8.3.2 Understanding stakeholder ently: “What counts is not what it is, but what perceptions people perceive it to be” (FAO 2004, 15). One The first steps in the ladder of adoption way of understanding stakeholder perceptions (table 8.1) and behavior change motivation fac- is to identify common ground, blind spots, and tors (table 8.2) deal directly with risk percep- knowledge that is hidden to one or another of tion. Risk perception is commonly thought of the parties. as a combination of what people know about a The Johari Window is a tool that enables risk and how they feel about it. Communica- these aspects of perception to be explored tion and capacity-building strategies should through dialogue and knowledge exchange account for both dimensions of risk percep- (figure 8.1). Use the four windows of percep- tion, as well as how different stakeholders per- tion to identify potentially differing percep- ceive the project as a whole. tions held by communities, government offi- This subsection explains that perceptions cials, funding agencies, and other relevant of different stakeholder groups will differ, and stakeholders. Consider perceptions relating to that vulnerability and uncertainty can play a motivations to reduce landslide risk, inten- role in shaping these perceptions. Make sure tions to act, the translation of intentions into different stakeholder perceptions of risk—and behavior, and factors that modify these inten- of the project—are recognized before develop- tions (as discussed in section 8.3.1). Be aware ing appropriate communication and capacity- of differences in community and government building strategies (sections 8.4–8.6). or funder perceptions of urban landslide risk and the project scope and benefits. Windows of perception Develop the communication and capacity- building strategies in such a way as to increase Different stakeholders are likely to perceive open knowledge areas (table 8.2) and posi- landslide risk and MoSSaiC projects differ- tively influence people’s motivations, inten- 3 1 2    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E FI G U R E 8 .1  The Johari Window for increasing common ground and knowledge among stakeholders WE KNOW WE DON’T KNOW They tell us 1. Open knowledge or THEY KNOW (feedback) 3. Their hidden knowledge common ground  We tell them (information) We learn together   THEY DON’T 2. Our hidden knowledge 4. Unknown or blind spot KNOW Source: Luft and Ingham 1950. tions, and behavior regarding landslide risk —— The bad thing is not going to happen. reduction. —— If the bad thing does occur, it will affect oth- ers and not me. Vulnerability and risk perception —— If the bad thing does affect me, the effects Vulnerability is related to the capacity to antici- will be minimal (FM Global 2010, 7). pate a hazard, cope with it, resist it, and recover from its impact. It is determined by a mix of • Procrastination. Procrastination is the physical, environmental, social, economic, tendency to postpone taking actions that political, cultural, and institutional factors require investment of time and money. (Benson and Twigg 2007). Although MoSSaiC • Short-term focus. This is the difficulty of is primarily concerned with reducing landslide computing benefit-cost trade-offs. hazards in vulnerable communities, there is a need to account for the influence of vulnerabil- • Hyperbolic discounting. Hyperbolic dis- ity on risk perception and the adoption of new counting is putting too much weight on slope management practices: immediate considerations rather than on the long-term benefits of investing in miti- The poorer people become, the more their gation. vulnerability to a variety of hazards increases and the more difficult it becomes to play one off against another to achieve security. Peo- The MCU and government task teams ple have to balance extremely limited should be aware of the potential effects of vul- resources to deal with threats like homeless- nerability on community perceptions of land- ness, landlessness, illness, and unemploy- slide risk and the project. Communication and ment. In general, people are unlikely to capacity-building strategies should be devel- change or adapt their living patterns and oped that address these risk perceptions and activities to reduce their vulnerability to nat- ural hazard, if it increases their vulnerability demonstrate that landslide hazard can often to other more pressing threats (Maskrey be reduced. Thus, a secondary benefit of 1992, 2). MoSSaiC can be increased community resil- ience (reduced vulnerability) stemming from a The effects of vulnerability on risk percep- greater capacity to understand, anticipate, and tion and the motivation to reduce landslide mitigate landslide hazards. risk can include the following behavioral biases (FM Global 2010): Uncertainty and risk perception • Deniability. Deniability is the belief that Risk perception and risk reduction behavior bad things will not happen: are affected by how experts, decision makers, CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 1 3 and those at risk (in this case, communities) interpreted. Encourage transparency in com- interpret uncertainty about that risk. A grow- munication between experts and other stake- ing source of uncertainty is arguably a shared, holders so that the possibilities of over- or common uncertainty about the results of haz- underprediction of landslide risk can be ard and risk modeling predictions, leading to a accounted for in community selection and the hesitation to invest in ex ante DRR. design of landslide mitigation measures. Increasingly complex hazard and risk mod- els, combined with uncertainty in model 8.3.3 Combining knowledge and action parameters, have resulted in disaster risk pre- Traditional risk communication and capacity- dictions with greater and greater uncertainty building strategies both tend to emphasize bounds. A consequence is that decision mak- transfer of knowledge from experts or deci- ers and the public may learn from one expert sion makers to laypeople. However, as the lad- that there is little to be concerned about for a der of adoption (steps 3–6) and behavior particular risk, and from another that the very change factors in section 8.3.1 indicate, knowl- same risk is of major significance (Kunreuther edge must be combined with action in order to and Useem 2010). Seemingly conflicting mes- change stakeholder perceptions and practices. sages are compounded by the fact that It is now well known that traditional knowl- the concepts, nature and implications of sci- edge transfer approaches can be ineffective entific uncertainty are not well understood unless balanced by other forms of communica- by policymakers and/or society… This causes tion and capacity-building activities (CADRI confusion when it comes to confidence in the 2011; World Bank 2010). Dialogue-based com- work that physical scientists produce (Mal- munication and learning by doing or action amud and Petley 2009, 167) learning are thus a fundamental part of com- and further uncertainty when deciding how to munity participatory approaches such as act. MoSSaiC. These messages and associated uncertain- Use this subsection to understand how ties will be processed in different ways by each knowledge and action can be combined to stakeholder—ignoring the message, trying to encourage behavioral change and to guide the find more information to reduce their uncer- inclusion of learning by doing in project com- tainty, or accepting the message that is most munication and capacity-building strategies. compatible with existing risk perceptions or Conventional knowledge transfer and disaster biases. risk reduction For example, among decision makers and politicians, uncertainty can generate a falsely Gaillard and Mercer (2012, 2) note that “the optimistic (biased) confidence that a cata- field of DRR is a battlefield of knowledge and strophic event will “not happen in my term of action, which often results in poor outcomes office” (Kunreuther and Useem 2010). Vulner- in terms of actual reduction of disaster risk for able communities may discount messages those most vulnerable.” Conventional West- about uncertain disaster risks in light of their ern-style education emphasizes written experience of more pressing threats such as knowledge as the precursor and only effective unemployment or illness (Maskrey 1992). basis for action (Crookall and Thorngate Such interpretations of risk are perhaps most 2009). The one-way transfer of knowledge is important for low-probability uncertain evident in top-down DRR policies that focus events because, unlike high-probability events, on classroom-based training, education, and personal experience is likely to be absent public awareness campaigns to increase (McNabb and Pearson 2010). knowledge and encourage behavioral change. The MCU and government task teams Yet it is understandably difficult for local deci- should be aware of uncertainties in model pre- sion makers, practitioners, and community dictions and how these uncertainties might be residents to turn scientific knowledge into 3 1 4    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E hazard reduction actions (GNDR 2011). The MoSSaiC projects involve learning by knowledge and practices identified at interna- doing: combining local and scientific knowl- tional and national scales are simply not trick- edge about slope stability; encouraging ling down fast enough to achieve DRR on the funders, governments, and communities to ground (Wisner 2009). develop and apply MoSSaiC in the context of Community-based DRR has, in part, local expertise, practices, and policies; and emerged as a response to conventional top- generating new knowledge through the pro- down approaches—focusing on vulnerability cess of putting MoSSaiC into action (table 8.3). rather than hazard reduction and emphasiz- MoSSaiC communication and capacity- ing community participation, local knowl- building strategies should include activities edge, appropriate technologies, and practical designed to enable or encourage participants actions. This approach addresses many of the to do the following (Crookall and Thorngate limitations of top-down national DRR poli- 2009, 19): cies, but usually cannot address the hazard • “[A]pply new knowledge to a practical situ- component of landslide risk. Even at the local ation” (knowledge into action) government level, “the knowledge base required to identify landslide prone areas is • “[G]enerate understanding, learn new often either nonexistent or fragmentary” skills, and gain new knowledge from a con- (UNU 2006). crete experience” (action into knowledge) Given the limitations of either purely top- • “[M]ake connections between actions and down or bottom-up approaches in addressing related knowledge” (integrating action and urban landslide risk, it is now recognized that knowledge). a combination of these approaches is required. Landslide risk reduction necessitates the inte- Use table 8.3 as a guide to review for each gration of different disciplines so that scien- stakeholder group what works locally in terms tific knowledge of the hazard is combined of knowledge into action and action into with local knowledge and appropriate actions knowledge activities. Use this review to inform (Malamud and Petley 2009); “we must avoid the development of communication and romanticising indigenous knowledge, and capacity-building strategies. combine it with scientific knowledge” (Pelling 2007, 16). Similarly, conventional top-down communication and capacity development 8.4 COMMUNICATION PURPOSE methods should be balanced by more informal AND AUDIENCE dialogue and participatory-based methods. A communication strategy is typically devel- Learning by doing oped by defining the purpose of communica- “Knowledge and action are closely inter- tion and identifying audiences, messages, and twined,” note Crookall and Thorngate (2009, appropriate forms of communication. 17), and the process of adopting new DRR Designing the strategy is an art, not a sci- behavior requires both to be present. Learning ence, and there are many ways of approaching by doing integrates learning, action, and reflec- the task. Table 8.4 presents five questions that tion; and is carried out during, rather than can help the MCU and communications task prior to, project implementation (IFRC 2008). team in organizing the necessary information Learning by doing goes beyond conventional and developing a strategy. classroom-based knowledge into action activi- Use this section to identify the purposes ties and public awareness education by empha- and key audiences of the communication strat- sizing action as a means for learning and gen- egy; use section 8.5 to help identify specific erating new knowledge. communication tools and messages. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 1 5 TAB L E 8 . 3  Knowledge and action as part of the adoption of the MoSSaiC process STAKEHOLDER KNOWLEDGE INTO ACTION ACTION INTO KNOWLEDGE Community task teams— • Detailed knowledge of slope history and • Residents involved in the process see the residents, leaders, and features (drainage, cuts/fills, soil depth, signs direct results of good slope management local contractors of instability) contributes to mapping and practices and simple measures in their own landslide hazard reduction design process households • New information about slope stability is • Good construction practices and new skills are provided by government generated and shared among site supervisors, • Contractors from within the community are engineers, and contractors engaged and apply existing skills MCU and government task • Engineering and technical knowledge is • Government team members develop new teams—engineering and increased and applied to design of landslide local knowledge and practices while working science practitioners hazard reduction measures on site and with local contractors in the • Site supervisors are briefed and oversee communities delivery of physical mitigation works MCU and government task • Knowledge of community context and dynam- • Learning the science from other team members teams—community ics is applied to enable community participa- and integrating community mobilization skills development practitioners tion in the project with hazard reduction agenda MCU, politicians, and • Decision makers, funders, and MCU briefed on • Project reports provide new evidence base for funding agencies MoSSaiC vision and the science of landslide policy change and innovation for adopting the hazard reduction approach more widely • Existing project management skills employed in new ways Academic researchers and • Application and development of landslide • Refinement of approach to landslide re- private sector consultants theory in the field search—experience of working with end users results in new priorities, scientific methods, and ways of communicating TA BLE 8 .4  Questions to guide the design of a MoSSaiC communication strategy QUESTION ACTION Are there resources already available Review existing methods and toolkits for communication in a for communication? development, DRR, or community participation context (e.g., IFRC 2010; Mefalopulos 2008; UNICEF 2008) What are the purposes or functions Review the MoSSaiC vision and foundations (chapter 1) and of the communication strategy? behavior change process (section 8.3.1), and identify communica- tion requirements (see section 8.4.1) Who are the audiences and Identify MoSSaiC stakeholders (table 1.16 and chapter 2); identify messengers? communication requirements and strength, frequency, and directions of communication flows (see section 8.4.2) How and when can these audiences Based on communication purposes and audiences, identify be best engaged? appropriate modes (written/verbal/visual, and one-/two-way), channels (face to face or mediated), tools, and timing (see section 8.5) What are the key messages for each Based on communication purposes and audiences, design audience? messages with appropriate content, language, and presentation style (see section 8.5). 3 1 6    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E 8.4.1 Defining communication purposes Each stakeholder can act as a messenger or and functions audience (or both) in a communication net- work with information flowing in one or many For MoSSaiC projects, the communication directions at different times during the proj- strategy serves the following purposes: ect. The characteristics of each audience should determine the form of communication • Raising awareness and changing percep- selected to suit the purpose of that communi- tions about urban landslide hazard risk cation: • Facilitating community participation, The importance of defining your target understanding, interaction, and trust groups cannot be overstated. Knowledge, among stakeholders beliefs, and customs often vary widely from one group to another and the ways in which • Providing information and managing knowledge is acquired are not the same in expectations about project implementation each community. Even within a given target and outcomes group, it’s important to learn how to segment (IDRC 2012, 2). • Generating new knowledge as part of a learning-by-doing approach The MCU should compile a list or commu- nication network diagram of audiences and • Encouraging the adoption of new landslide messengers. For each audience, consider per- risk management behavior. ceptions, motivations, and intentions regard- As the World Bank (2010, 327) notes, ing landslide risk and the potential for adopt- Well-designed communication cam­ paigns ing new risk reduction behavior (section that address individuals as members of a local 8.3.1); the cultural, political, and social con- community—and not as power­ less members text; and local factors that might affect com- of an unmanageably large group—can munication and limit behavior change (table empower them to act. This treatment can help 8.5). Use tools like the Johari Window (fig- make a global phenom­ enon personally rele- ure  8.1) and baseline studies to help under- vant and immediate, and accentuate the local and individual ownership of the solutions. stand stakeholder (audience and messenger) perceptions. This analysis will help identify The MCU should review the purposes that communication requirements in terms of communication will serve and use these pur- appropriate forms of communication and poses to guide the development of the commu- messages (section 8.5). nication strategy. 8.4.2 Identifying audiences 8.5 FORMS OF COMMUNICATION MoSSaiC stakeholders include the following: AND PROJECT MESSAGES • Project funders Forms of communication can be classified in • Politicians and government decision makers terms of modes, channels, and tools: • MCU and government task teams • The basic modes of communication are written, verbal, and visual; and one way • Community task teams (including individ- (information transfer) or two way (consul- ual residents) tation or dialogue). • Landowners. • Communication channels are either face- Additional audiences may include the gen- to-face (direct) or mediated (indirect), and eral public, regional MoSSaiC user groups, and either target specific individuals or groups, the scientific community. or diffuse audiences. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 1 7 TA BLE 8 . 5  Examples of local factors affecting communication FACTOR EFFECT ON COMMUNICATION Community • There may be views regarding who should have assistance that are embedded within perceptions social groups and not in accord with likely project recommendations • Perceptions regarding landslide risk and mitigation measures may vary from one community to another, thus requiring different messages • Government agencies and staff may not initially be seen as trustworthy Social behavior • Where a community is highly polarized by criminality or other factors; this situation could make project acceptance difficult to achieve Perceptions of • Cultural differences in the perception of time could affect project time frames (e.g., timing where a laissez faire attitude is prevalent) Government • Different parts of established government bureaucracies may send different messages messages regarding DRR priorities and practices Political • Communities might move faster than government in recognizing the need for DRR agendas • DRR may be low on the current government agenda, but high on that of the political opposition parties History • Project fatigue among residents may mean that motivational messages need to be stronger than simply justifying the science of the intervention Gender • Women may be the day-to-day decision makers in the household, but have less exposure to certain communication methods Landownership • Project messages need to take into account local landownership protocols Meetings • Views expressed in meetings may reflect dominant rather than majority views and could reflect special, undeclared, interests Stakeholder • Critical stakeholders may not be reached by some forms of communication (e.g., availability landlord residing overseas) • Different communication tools are appro- to achieve project objectives and encourage priate for different modes and channels of behavioral change. Communication tools communication as illustrated in table 8.6. should be used as part of the overall project process rather than as stand-alone outputs MoSSaiC projects need to use a wide range (e.g., landslide maps, posters, leaflets, or a TV of communication modes, channels, and tools documentary). TA BLE 8 . 6  Examples of communication tools by mode, channel, and purpose MODE, CHANNEL, PURPOSE TOOL One-way communication to provide • Leaflets, posters, information packs information indirectly with no feedback • Newsletters, project updates mechanism • Reports, documents, protocols • Exhibitions, demonstration of technologies • Mass media (TV, radio, newspapers) Two-way communication to seek information • Site visits and feedback indirectly or face to face • Consultation documents, surveys • Formal public meetings, presentations Two-way communication and dialogue to • Interactive mapping, workshops, and training activities facilitate mutual exchange, understanding, • Consensus-building meetings, mediation and stakeholder participation • Various community participatory tools Source: Burgess and Chilvers 2006. 3 1 8    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E Direct two-way communication (consulta- and the media (TV and radio), are introduced tion and dialogue) is particularly important for in sections 8.5.2–8.5.5. These forms can be community participation and learning by used to support community participation and doing during community selection and map- learning by doing, and are the primary means ping, drainage design and construction, and of providing information to a wider and more postproject maintenance. These forms of com- dispersed audience. munication are summarized in section 8.5.1 Use table 8.7 to assist in deciding what with respect to project audiences. forms of communication are best suited to Selected examples of indirect forms of com- each stakeholder audience and purpose, after munication, using written and visual materials reviewing sections 8.5.1–8.5.5. Determine TAB L E 8 .7  Deciding which forms of communication to use for each stakeholder audience WHO (AUDIENCE) WHEN AND WHY (PURPOSE) HOW (FORM) Funders Throughout project: • Project proposals and reports • Fulfill formal reporting requirements • Invited site visits • Raise awareness • Informal briefings on project impact • Advocate for policy change Politicians and Especially at key project milestones: • Site visits by government officials recorded and government decision • Fulfill formal reporting requirements reported by the media makers • Briefings to elected community constituency • Raise awareness representatives • Seek public endorsement • Advocate for policy change • Cabinet briefings MCU, government task Especially at early project stages: • Training materials for formal classroom-based and teams • Create familiarity with MoSSaiC approach on-site training • Provide technical information • Formal and informal interaction with community teams and residents • Generate new knowledge • Facilitate engagement with community • Practical experience and dialogue with community • Change DRR practice Community task teams, Throughout project: • Community meetings community residents, • Raise awareness • Demonstration homes landowners • Provide technical and project information • Posters and leaflets • Facilitate participation in project • TV, newspaper, and radio coverage • Generate new knowledge • MoSSaiC certification of key community contractors • Change DRR behavior • Knowledge transfer among communities General public Throughout project, especially at construc- • TV, newspaper, and radio coverage tion/completion phases: • Leaflets available on request • Provide information • Raise awareness Regional MoSSaiC user At project completion: • Workshops groups and regional • Provide information • Conferences stakeholders • Facilitate knowledge sharing • Short write-ups of case studies • Internet community of practitioners Academic and Throughout project: • Publication of research papers in academic and professional community • Peer review and dissemination of science, professional journals (science, engineering, methods, and project outcomes • Presentation at academic conferences social science) • Collaborative research CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 1 9 whether these forms of communication will wins… In a dialogue, there is no attempt to gain be considered appropriate and trustworthy by points, or to make your particular view pre- their audiences. Identify key messages for vail.” each audience and which forms of communi- Specific tools for this form of communica- cation will convey those messages most effec- tion include the following: tively (section 8.5.6). • Consultation documents, surveys, site visits 8.5.1 Direct communication, • Formal meetings, presentations consultation, and dialogue Direct two-way communication encourages • Interactive mapping, workshops, and train- behavioral change by allowing stakeholders to ing activities understand one another’s perceptions, collab- • Consensus-building meetings, mediation orate on project activities, and learn from each other (see table 8.8 for examples). Boham • Community participation tools such as col- (1996, 2) notes that “In a dialogue, nobody is lective mapping, priority ranking, and trying to win. Everybody wins if anybody observation walks TAB L E 8 .8  Examples of direct two-way communication tools for use throughout the MoSSaiC project process MoSSaiC PROJECT ACTIVITY TOOL Building the MCU government • Formal meetings to present the project concept to government decision makers and task teams (chapter 2) agencies and to consult on the selection of MCU and government task team members • Consensus-building and planning meetings within the MCU and the government task teams to agree on project steps Understanding landslides • Education/training on landslide risk for landslide assessment and engineering task team (chapter 3) • Presentation of landslide information by experts to all stakeholders throughout the project Selecting communities • Consultation among the MCU, government task teams, local government agencies, and (chapter 4) communities to collect basic landslide risk information • Site visits and consensus-building meetings to agree on community selection Community-based mapping • Formal meetings and presentations to raise community awareness of landslide risk and (chapter 5) MoSSaiC project • Consultation with community to identify representatives • Community participation tools (observation walks, mapping, and priority ranking) to identify landslide hazards and solutions • Informal (on-site) training of government task teams Drainage design • Education/training on drainage design for landslide assessment and engineering task team (chapter 6) • Consensus-building meetings and focus groups to agree on a drainage plan with government decision makers and the community • Formal meeting/presentation of drainage design to community and government decision makers Implementation of works • Formal (classroom-based) and informal (on-site) training for local contractors and site (chapter 7) supervisors and (if relevant) community teams involved in procurement • Mediation between residents and those working on site • Invited site visits for government decision makers and funders Postproject maintenance and • Consultation and consensus building on approach to maintenance evaluation (chapter 9) • Formal project completion ceremony for all project stakeholders • Site visits, focus group meetings, and consultation with all stakeholders to determine project impact and lessons learned 32 0    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E Using direct two-way communication for • Turn off mobile phones and stay present MoSSaiC projects throughout meetings These communication tools are used through- • Respect opinions and include all partici- out the MoSSaiC project to facilitate collabo- pants ration among key government and community • Remember that active listening can be as stakeholders. To understand and apply these important as speaking tools, the MCU and government task teams should review their use in the context of their • Be frank and answer questions honestly specific purpose for MoSSaiC; see table 8.8 as a • Keep explanations brief and easy to under- guide. stand Delivering project messages • Provide practical guidance on community The approach that the MCU and the govern- actions ment task teams adopt for communicating • Use flipcharts, maps, leaflets, and other with communities will determine the extent to visual interactive tools as a means of shar- which they are accepted and trusted by them ing information. and how effective project messages will be in encouraging behavioral change: Identify the best means of notifying com- Any strategy intended to effect change in a munities about project meetings and site vis- community should be discussed with, under- its—e.g., word of mouth, communication via a stood and agreed upon by the community, since the primary decision-makers about community leader or representative or by an what and how to change are the very people individual who is paid to make community who are going to be affected by the change announcements. (FAO 2004, B1). 8.5.2 Community demonstration sites Consider local customs, norms, and and show homes resources that will guide the approach to two- In many vulnerable communities, the best way communication in communities. Take form of communication is highly visual and guidance from the community liaison task based on demonstration. Visits to sites of past team and community representatives to iden- hazard events and demonstration of successful tify ground rules for government task teams hazard mitigation measures is a powerful way engaging with communities. In this regard, of changing perceptions about how to tackle note the following (IFRC 2008 and Mefalopu- hazards effectively. Demonstration sites, los 2008): example infrastructure, and show homes in • Agree on the timing, location, and purpose communities provide tangible evidence that of meetings and site visits with community can help governments and communities envis- representatives beforehand age what they might have the capacity to do in similar situations (self-efficacy). Combining • Chose meeting venues that are accessible to demonstration sites with information materi- the community als and training allows people to understand • Start and finish meetings and site visits and adopt risk reduction behavior. promptly MoSSaiC demonstration sites and show homes • Respect cultural formalities and language Completed MoSSaiC projects provide the in addressing individuals and groups context for demonstrating urban landslide • Be aware of unspoken messages conveyed hazard solutions such as surface water drain- by body language and conduct age networks, houses with roof guttering, CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   32 1 rainwater tanks, and gray water connections • Collection of gray water from kitchens and to drains. When viewed in the context of past bathrooms landslides at similar sites, demonstration • Connection of all household water into sites enable community residents and invited lined drains visitors to see practical examples of how landslide hazard can be reduced by house- • Use of low-cost drain construction where holds. appropriate During the community mapping and drain- • Monitoring of groundwater levels, if appro- age design phases, and guided by the govern- priate (see chapter 9) ment task teams, community residents should select a potential show home by agreement • Monitoring of any cracks in the house (see with the owner. Ensure that the householder chapter 9). has a genuine commitment to the concept and Use table 8.9 to help identify the use of to the exposure within the community it could demonstration sites and show homes as part of bring. Equip the show home with the follow- the project communication strategy. ing drainage features as an integral part of the wider community drainage intervention (fig- Delivering project messages ure 8.2): Demonstration sites and show homes can • Guttering and downpipes to drain the roof change the perceptions and motivations of FI G U R E 8 .2  Show homes a. Show home located prominently within b. Signage posted on the show home’s c. Show home erected by a commercial a community; note gray water pipes property helps reinforce the message of company is in a prominent roadside connected to a new drain. good surface water management. location for maximum impact. TA BLE 8 .9  Example uses of demonstration sites and show homes during the MoSSaiC project process MoSSaiC PROJECT ACTIVITY LOCATION PURPOSE (AND KEY AUDIENCE) Understanding landslides Sites of previous • Raise awareness of MoSSaiC landslides approach and good/poor landslide Selecting communities hazard reduction practices Drains and show (government stakeholders and homes in communi- community representatives) Community-based mapping ties with completed • Provide context for training (site MoSSaiC projects Drainage design supervisors and contractors) Implementation of works New drains and show • Raise awareness of good landslide homes in current hazard reduction practices Postproject maintenance and evaluation MoSSaiC project (community residents) 32 2    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E communities by demonstrating that house- • Transmitting information more rapidly, holds have the capacity to manage roof and realistically, and accurately than verbal gray water effectively and contribute to land- messages slide mitigation. Such example infrastructure MoSSaiC information materials can also change perceptions of contractors and government stakeholders about the Appropriate written and visual information impact and effectiveness of relatively low-cost, materials should accompany and support simple measures for mitigating landslide haz- other forms of communication to project ards. stakeholders, especially communities. The The visibility of the house and the accom- community slope feature map and drainage panying drainage and pipework is vital for this plans are central to the project and can be a to be an effective communication tool. A draw- helpful visual tool for communicating slope ing of the house could subsequently be incor- processes, hazardous locations, the rationale porated into posters, which may then be used for drainage routes, and the construction pro- by the media for further promotion. cess. Written and visual tools should also be Some commercial housing providers used in explaining urban slope stability pro- exhibit show homes (figure  8.2c). With gov- cesses, what the MoSSaiC project process is, ernment support, encourage local commercial how slope drainage and good slope manage- firms to partner with the project so that ment practices can help, and why and how MoSSaiC drainage interventions can be given drains should be maintained. Such tools additional visibility. This measure could also should allow an appreciation of the commu- help in advocating the inclusion of sound nitywide approach to slope stability as well as household-scale slope drainage practices in personal actions and responsibilities. building codes. The frequent absence of legally Use table 8.10 as a guide in using written binding building codes and mandatory con- and visual tools in communities throughout struction standards means show homes have a the project. potentially highly influential role to play in the Delivering project messages communication strategy for landslide hazard reduction. The local cultural and educational context will determine the relative efficacy of different 8.5.3 Written and visual materials for written and illustrated media in vulnerable communities communities. The MCU should determine Materials that provide information in a com- whether written media such as maps, posters, bined written and visual format can be a pow- cartoons, and leaflets are likely to be effective. erful way of communicating. Communication Consider levels of literacy, formality/informal- tools such as photographs, maps, graphs, dia- ity of language used, and the balance of writ- grams, and cartoons can help audiences under- ten and visual material. Where appropriate, stand risks and risk reduction behavior in the use images or illustrations of familiar locations following ways identified by Lundgren and in the community to show relevance and McMakin 2009: encourage ownership. Pretest materials with community representatives to ensure they are • Providing information in a memorable way culturally relevant and appropriate. • Clarifying abstract or complicated concepts Communication tools should be matched to message and purpose, as these examples illus- • Revealing patterns and trends that would trate: otherwise be hidden • Fliers and meeting invitations should be • Encouraging comprehension and problem personal and to-the-point to generate inter- solving CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   32 3 TA BLE 8 .1 0  Examples of written/visual materials to be used during the MoSSaiC project process MoSSaiC PROJECT ACTIVITY MATERIAL PURPOSE FOR COMMUNITIES Community-based mapping Posters/leaflets on MoSSaiC Raise community awareness of project and slope stability MoSSaiC and of urban landslide causes and solutions Community plans for use during Provide opportunity for residents mapping process to contribute knowledge to and participate in project Drainage design Poster-size plan of drain locations Provide information and opportu- displayed at meetings and in nity for community involvement in prominent community location design of planned works Implementation of works Leaflets on slope drainage, slope Raise community awareness of management, and drain mainte- good practices for landslide risk Postproject maintenance and nance practices reduction evaluation est in the project and provide at-a-glance ering points. Posters can provide a focal information about how to participate. point for meetings, training, TV reports, and endorsement and advocacy of the proj- • Leaflets and fact sheets can be used to pro- ect by policy champions (figure 8.5). vide detailed information that can be read and reread by people at home. 8.5.4 TV, radio, and newspaper coverage • Maps can either be stylized to convey sim- Local and national TV, radio, and newspapers ple project concepts, or accurate and realis- can be used to disseminate risk information tic to convey exact spatial scale and co-loca- and messages to project stakeholders and the tion of features. wider public. The content, messages, and • Posters should be designed to attract audi- effect of media coverage depend on who sets ence attention and convey one or two mes- the agenda. For example, official government sages simply and legibly from a minimum messages may focus on mitigation and reas- distance of 1 meter away. surance, while media outlets can be drawn to Use these materials to reinforce other forms disaster impacts and drama (Höppner et al. of communication during the project: 2010). News coverage will often tend to be event • Distributing fliers or meeting invitations based and may be initiated by the media or by provides the opportunity for residents to government risk managers. Governments may ask questions and engage with the project, commission risk communication campaigns regardless of whether the leaflet is actually with sustained media coverage using a variety read or not (figure 8.3). of formats (such as news items, discussion • Leaflets and small versions of posters can forums, documentaries, and human interest be used during house-to-house conversa- stories) to generate interest, influence percep- tions and on-site training to help explain tions, and change behavior. the science and to show good construction MoSSaiC media coverage and slope management practices (fig- ure 8.4). Media coverage can be appropriate for MoSSaiC projects as a way of communicating • Obtain permission to display posters in information about the project itself and about prominent locations such as shops and bars, urban landslide risk reduction. Ensure that community centers, or other natural gath- there is a member of the MCU or communica- 32 4    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E FI G U R E 8 . 3  Meeting invitation and project flier given to community residents at project start Community meeting 6pm, 12th September Improving slope stability and drainage in our community You are invited to the community anding slopes Understanding opes slo s centre to talk with leaders of the Government Risk Reduction initiative a affected affect af f affe ffe ff fe fec f ec ec cted ted ctee by changes in: about how to improve slope stability 1 slope geometry - and drainage in this community. e.g. making it steeper rai infall f ll rainfall The following proposed project plan slope loading - 2 e.g. building a house will be discussed: rock soil the strength of the soil - e.g. adding water and/or Phase 1. Pilot project - providing removing vegetation 3 drainage to improve slope stability in the most at-risk area (10 houses) 1 Water from roofs wa Phase 2. Extend main drains in whole 2 Water from ground surface te r l eve l in ground rises community and connect households 3 Un-lined drains and gullies (100 houses) 4 Water from household plus foul water Organised by the Community Committee What can be done by each household: Improving use guttering to catch rainwater on the roof drainage to direct all roof and grey water into lined drains make slopes keep main drains clear of debris safer report cracks and leakage in drains report leakage in piped water supplies ...you may think of other ways of reducing the water going into the slope... FI G U R E 8 .4  Example of a leaflet or small poster to use in informal conversations with residents MoSSaiC www.mossaic.org 5 Steps to safer slopes when you build on the slopes Management of Slope Stability in Communities water tank roof-guttering Water from roofs Water poured Build drains next to paths downpipe onto ground and connect drains Water from taps kee to each other & leaking pipes p wa te waste water pipe r o slo p es *Monitor water 5 levels in slope en th of tube Make drains watertight drain with plastic * or concrete drain th tpa foo Debris & Channel all water to drains: rubbish Roof water Keep drains clear of rubbish Waste water Over-steepened and vegetation slope Close housing Vegetation * MoSSaiC can provide further information on i) easy-to-install, low-cost Things to avoid... removed plastic drainage and on ii) water-level monitoring. Please ask for details. plastic drainage and on ii) water-level monitoring. Please ask for details. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   32 5 F IG U R E 8 . 5  Using posters to convey project messages Improving slope stability through better drainage ... Roof guttering Drain above house collect water for storage catch surface water connect to downpipes from upslope and nearest drain Mellisa Charles' house Household waste water pipes connect to nearest drain standpipe STAR drainage system connect to main drains easy to install low cost a. Design a poster illustrating good slope drainage b. Display the poster prominently on the wall of a practice. community shop, bar, or meeting place. c. The displayed poster is here filmed for inclusion d. A senior government official uses the poster to in a TV documentary on MoSSaiC. explain the intervention during a training course for government staff. tions task team who is experienced in working content of coverage before inviting the media. with the media, or seek assistance from Use table 8.11 to guide the use of media cover- another government agency or approved age during the project. media outlet. Delivering project messages Identify windows of opportunity in the project process (meetings or milestones) and Radio and TV interviews are likely to be activities such as mapping and construction requested by the media at initial project stages, and human interest stories that will lend including the decision to fund the project and themselves to media coverage. Consult with the selection of communities. At these early government task teams and community repre- stages, it is important to manage expectations sentatives to agree on the message, scope, and by giving clear information about what the 32 6    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E TAB L E 8 .11  Examples of media coverage during the MoSSaiC project process MoSSaiC PROJECT ACTIVITY TV, RADIO, AND NEWSPAPER COVERAGE PURPOSE FOR WIDER AUDIENCE Selecting communities Press release to announce MoSSaiC Information and transparency, and to raise project in selected communities awareness of the MoSSaiC approach Community-based mapping Tell community and science stories Raise awareness of local landslide causes Drainage design and solutions Implementation of works Postproject maintenance and Recap community and science stories and Change perceptions of, and motivations evaluation show evidence of effectiveness for, urban landslide risk reduction project is designed to achieve and how com- F IG UR E 8.7  Opening frame of a MoSSaiC munities will be selected. TV documentary Arrange for media presence during con- struction and interview leading community figures who are actively engaged in the project (figure 8.6). Media presence within a commu- nity adds momentum to a project and builds a sense of ownership among community resi- dents. For live interviews especially (which do not allow for subsequent editing), have a clear message—say who the project participants are and what the project is doing to reduce the landslide hazard. A documentary focusing on the project can be a powerful means of raising public awareness, TV documentaries can be used by govern- and of giving a strong sense of ownership to ments to raise awareness of and report on the community and to those engaged in project outcomes (figure 8.7). Ensure that supervising and managing the project. there is footage of community engagement, Source: Government of St. Lucia. particularly during mapping and construction. FI G U R E 8 .6  Media filming during construction a. Filming community contractors during low-cost b. A community resident (also a contractor) drain construction. Media presence in such explains the project to a local TV station. Having circumstances is usually positively received by community members tell the story can be more vulnerable communities. powerful than project managers doing so. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   32 7 The TV program can be repeated when subse- address the communication gaps between quent MoSSaiC projects start in new commu- these various actors. Potential solutions nities. The advantages and associated risks of include adopting new paradigms to combine this programming style should be reviewed hazard and vulnerability reduction approaches before a program is commissioned (table 8.12). and developing new knowledge exchange General guidelines for imparting messages to mechanisms, ways of communicating scien- the media include the following: tific information and uncertainty, multidisci- plinary collaborations, and action-research • Keep it simple; use words people under- approaches (Malamud and Petley 2009). stand. MoSSaiC takes a multidisciplinary • Be clear and avoid detailed explanations. approach to delivering community-based, sci- ence-based, and evidence-based landslide risk • Describe, simply, what the project does, not reduction measures. This specific collabora- how it works. tion of DRR researchers, practitioners, and • Describe the differences the project will policy makers lends itself to dissemination of make to the local community. project research and results in professional and academic circles. • Give a human story—explain what the proj- Publishing an article in a local professional ect will do for an individual. magazine or academic journal, with key proj- ect participants as coauthors, can be a good Many organizations provide comprehen- communication channel for the following rea- sive media guidelines for community develop- sons: ment and DRR projects—see, e.g., UNDP • Academic journals require papers to be (2012) peer reviewed, thus providing feedback and 8.5.5 Scientific and professional critical evaluation of the project, opportu- publications nities to learn, and subsequent credibility once accepted for publication. There is a gap between DRR knowledge and action—and between researchers, policy mak- • Articles in local publications will be read by ers, different academic disciplines, and related colleagues in government and private com- professions such as engineering (Gaillard and panies who may be participants in deci- Mercer 2012). Efforts are being made to sions relating to MoSSaiC. TA BLE 8 .1 2  Factors for the MCU to consider when commissioning a TV documentary ADVANTAGE RISK • Very much a “gold standard” as far as media • Another organization may be in charge of the recognition is concerned overall message sent • Likely to have a long shelf life • There is no guarantee that all elements of • Professionally produced MoSSaiC will be covered • By being filmed in a familiar location/context, a • Production costs for a professional media house locally produced documentary can raise can be high awareness that landslide hazard can be addressed • It may not be possible to capture the full impact in similar communities of the intervention, e.g., drains flowing during • Could attract the attention and endorsement of major storm events a prominent and respected person • Dominant, rather than representative, views may • Can be used in subsequent team training be expressed by those community residents who volunteer to participate 32 8    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E • Articles may reach a different audience dictions and the performance of previous than those for TV and radio programs. interventions; and • Any article will have a reasonably long shelf • an example of risk reduction community life, and thus be an accessible resource for a action: a real-life example involving com- period of time likely exceeding that of a munity residents. radio interview, for example. • Other construction initiatives are typically 8.6 WAYS OF BUILDING LOCAL showcased in local professional maga- CAPACITY zines—an article on MoSSaiC would raise awareness of the relationship between con- struction and landslide hazard. Capacity building for changing landslide risk reduction behavior involves more than just the • Having a tangible item (an article reprint) transfer of new knowledge about how to means copies can be shared with commu- understand and reduce landslide hazards in nity residents; this may be the first time communities. MoSSaiC projects should build they have seen their community featured in and develop “the abilities, relationships and such a key way. This will add to residents’ values” of governments and communities feeling of being valued, which is so impor- (UNEP 2002). Developing landslide risk tant in a community-based project. reduction abilities requires a combination of 8.5.6 Finalizing project messages activities that put knowledge into action and generate new knowledge through action The communication strategy is finalized by (learning by doing). These abilities, or techni- designing messages for the various stakehold- cal capacities, must be supported by the devel- ers. In this regard, “[k]eep in mind your mes- opment of functional capacities—funding and sage should—inform the head, impact the policies, collaboration among government heart and move feet into action!” (IFRC 2010, agencies, and community participation. 47). In behavior change terms, capacity-build- Design messages that persuade stakehold- ing activities can influence risk perceptions, ers to support a community-based approach to belief in the ability to address the risk (effec- landslide risk reduction. The messages should tiveness of actions, availability of resources, explain and expectation of positive outcomes), sense of responsibility, and empowerment. Table 8.13 • one main point: community-based land- identifies the capacity requirements for slide mitigation works and pays, in many MoSSaiC projects to influence landslide risk cases; reduction behavior at the individual, organiza- • what is being proposed: management of tional/group, and institutional levels. surface water in the community; Similar principles underpin MoSSaiC capacity-building and communication strate- • why it is worth doing: to achieve a reduc- gies. Both should involve a balance of one-way tion in landslide hazard; (information and knowledge transfer) and • the actions required by the community: two-way (dialogue and interactive learning by active participation throughout the project, doing) and formal and informal activities. especially regarding community mobiliza- Examples of capacity-building approaches tion and construction; and tools are presented in table 8.14. The MCU should use the capacity guides • the logic and research upon which it is from the previous chapters to identify specific based: evidence that the intervention technical and functional capacities that need should work, including slope stability pre- building or developing. Engage relevant stake- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   32 9 TA BLE 8 .1 3  MoSSaiC capacity requirements at individual, organizational, and institutional levels LEVEL WHO IS INVOLVED CAPACITY REQUIREMENT Individual • Community residents and • Scientific and local knowledge on landslide hazard contractors causes and solutions • Government task team • Experience in how to reduce landslide hazards members • Confidence in ability to act effectively • MCU Organizational • Community leaders; • Sense of shared responsibility and project ownership community as a whole • Processes and protocols to enable multidisciplinary/ • MCU agency approach • Government decision • Experience in working as a team to deliver solutions makers on the ground • Regional user groups • Community of practitioners Institutional/ • Government decision • Evidence for investing in ex ante landslide hazard societal makers reduction (enabling • Funders • Policy processes for enabling MoSSaiC projects and environment) sustaining project outcomes • DRR researchers • Research informed by policy and practitioner needs TA BLE 8 .1 4  Examples of capacity-building tools by learning mode MODE TOOL Knowledge transfer (knowledge into action) • Formal classroom-based workshops and training • Presentations • One-way communication Learning by doing (action learning, or action into • Interactive mapping, workshops, and training knowledge) activities conducted on site during project implementation • Various community participatory tools Knowledge exchange and mutual learning • Conferences • Peer-to-peer learning, mentoring, and coaching • Communities of practitioners holders in assessing these requirements, and For many MoSSaiC project roles, it is impor- use this section to identify appropriate capac- tant to both develop an individual’s capacity ity-building activities for individuals, teams, and provide mechanisms for accountability as and decision makers. they carry out their responsibilities. Supervi- sion, coaching, mentoring, and accountability 8.6.1 For individuals to peers can help fulfill these two require- Recognize and engage the expertise and skills ments. For example, site supervisors should individuals already have by inviting their par- provide impromptu training and instruction to ticipation and assigning appropriate roles and contractors and workers during construction; responsibilities. Provide training in a group engineers can mentor technical staff or train- setting (see section 8.6.2) to enable the devel- ees; and members of the MCU should support opment of new skills, knowledge, and confi- the government task team members. dence and to allow individuals to take on new Acknowledge the achievements of individ- responsibilities. uals who have completed high-quality work, 33 0    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E attained new skills or knowledge, or played an important role in the project. One way to do F IG UR E 8.9  MoSSaiC training in the Eastern Caribbean this is to devise a formal recognition (certifica- tion) process for individuals (section 8.8.3). The MCU should have the certification pro- cess formally approved by the government or an appropriate body, since the legal and administrative basis for awarding certificates or for formal recognition can differ from coun- try to country. Certification should be formally recorded for the individual. This builds self-esteem among those in vulnerable communities and of government task team members, and pro- vides a tangible form of recognition that should help in medium-term capacity building (figure 8.8). 8.6.2 For teams Create training courses for the MCU and for the government and community task teams. This training is best achieved through a com- bination of classroom-based and on-site The MCU-led training comprised both in-class instruction (figure 8.9). Where feasible, course and on-site sessions. instructors should include community resi- dents and contractors who have received for- 8.6.3 For politicians mal recognition for their skills and knowledge. Make site visits an integral part of training. Politicians need information. They need facts Include active participation by attendees in about a project to understand the rationale exercises that relate to the preparation of the and to be able to convey this information to the community slope feature map, slope process media (figure 8.12a) and to government and zoning map, and each stage in the develop- community groups, as opportunities arise. ment of the final drainage plan (figures  8.10 Demonstrate evidence of project effectiveness and 8.11). by organizing site visits where politicians can FI G U R E 8 . 8  Community surveyor and contractor receive MoSSaiC certification CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   33 1 F IG U R E 8 .1 0  Building team capacity F IG UR E 8.12  Building political capacity a. Ensuring a media presence when politicians and community members talk about the intervention on site is helpful in promoting the vision of community-based interventions more widely. b. Showing politicians a completed interven- tion on site helps build potential political champions. Government technical personnel work together to produce community slope feature maps and review completed construction. see results for themselves (figure 8.12b). The added benefits of site visits are that politicians see structures in place and talk with commu- FI G U R E 8 .11  Combined slope process zone map and initial drainage plan nity residents, who may then take the opportu- nity of reinforcing messages on related com- munity needs. Site visits with politicians build capacity by fostering interaction among the core stake- holders (government staff and community residents), and often stimulate immediate fol- low-on actions such as cabinet briefings and advocacy, instigated by the participating poli- ticians. 8.6.4 For communities Community participation is the main mecha- nism for building DRR capacity in communi- ties. Chapter 5 introduces some general com- 332    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E munity participation principles and identifies • Share the science and rationale for the specific principles and practices related to intervention (figure 8.13a). MoSSaiC. The MCU should also review guide- • Discuss the prioritization of certain areas lines on community participation for develop- and the location of drains. ment and DRR from international develop- ment agencies and practitioners (see, e.g., • Encourage the community to participate in ALNAP 2003; Mansuri and Rao 2003; Maskrey decision making. 1992; World Bank 2010). • Provide supervision and on-the-job train- Consider how the approach to community ing for contractors. participation is related to capacity for behavior change—from awareness, interest, knowledge, • Create opportunities through site visits and and attitudes, to legitimization, practice, and local media for community residents to be adoption of new landslide hazard reduction heard by politicians, decision makers, and behavior. Identify the balance needed between the wider public. providing information and formal training and • Award certificates to residents and contrac- empowering the community to take part in tors. identifying, designing, implementing, and maintaining landslide mitigation measures. • Get community residents to assist in the training of government staff and members Dialogue and exposition of landslide haz- of other communities for subsequent proj- ard mitigation measures and project processes ects (figure 8.13b). can build trust between community and gov- ernment. Government task teams should spend a significant proportion of their time in 8.6.5 For all user groups communities to build local capacity during the Organize a stakeholder conference to share mapping, design, and construction phases of best practices after several MoSSaiC interven- the project. Specific capacity-building activi- tions have been undertaken. Report on issues ties to be engaged in include the following: that might have arisen during the project, and • Learn from the community and gain local receive community residents’ reactions to the knowledge. process. Such a meeting should build trust FI G U R E 8 .13  Building community capacity a. During implementation is one of the best times b. Community members who have also been to engage with community residents and for them community contractors on MoSSaiC projects to engage with each other as they discuss project should be used wherever possible to provide progress and assist in minor elements of redesign on-site instruction to help build capacity and as the construction takes place. further develop individual self-esteem. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   333 across a wide constituency and thus be a sig- tices learned during project implementation nificant capacity-building exercise. For some and to embed these in their everyday activities. residents, it will be the first time they have This includes maintaining the infrastructure attended a conference or workshop, giving provided during the project as well as initiat- them increased levels of self-esteem. ing new projects. Hold discussions on site as well as in a con- Postproject maintenance of the drainage ference environment (figure 8.14), as informal infrastructure is critical to the success of the dialogue captures valuable insights into how MoSSaiC intervention. Maintenance allows project delivery might be improved. infrastructure to function according to the purpose for which it was designed and con- F IG U R E 8 .1 4  Building regional capacity: In structed. Many studies have shown that timely conferences and on site maintenance delivers cost-effective benefits (World Bank 1994), and disregarding mainte- nance “can cause larger expenditures in the future, it can also impose an additional, imme- diate, cost to users” (Rioja 2003, 2282). Use this section to develop a plan for main- taining drainage infrastructure as part of the overall strategy for behavioral change. Finally, integrate the communication and capacity- building strategies into the project plan and identify key outcomes for evaluating the level of behavioral change. 8.7.1 Encouraging adoption of good drain maintenance practices Three strategies for postproject maintenance can contribute to the overall behavioral change strategy: designing and constructing drains with ease of maintenance in mind, assigning maintenance responsibilities, and involving the community. Promote good drain design and construction supervision 8.7 FINALIZING THE INTEGRATED Drains can be designed and constructed so BEHAVIORAL CHANGE that maintenance is made easier—e.g., by STRATEGY reducing the likelihood of siltation or blockage by debris, creating access points for drain Both communities and governments need to cleaning, restricting access where drains go adopt new practices and policies if urban land- through people’s properties (to prevent tres- slide hazards are to be tackled effectively and passers), and controlling flow velocities to sustainably. Integrating communication and limit erosion or scouring of the drain or over- capacity-building strategies into the MoSSaiC topping in high flows. project process can help change people’s per- Modest structural design details can result ceptions, awareness, and knowledge, as well as in significant maintenance savings. Small their motivations and capacity to act. drains flowing under paths should be designed The final step in the ladder of adoption is to increase flow velocity and be self-cleaning for stakeholders to continue to use the prac- by having smooth alignments and increased 33 4    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E gradient. Conversely, baffle walls, steps, and creating new drains across the hillside that rip-rap should be used to reduce flow veloci- could provide access routes for criminals and ties on steep sections of the drain and prevent create new insecurities for residents (fig- damage. Debris and silt traps should be incor- ure  8.15b). Such incidents cannot necessarily porated into the drain design at locations be eliminated, but can be moderated by incor- where the flow gradient or velocity changes, porating suitable design details such as new resulting in sediment or debris being depos- fences to prevent unauthorized access to sec- ited, such as prior to vulnerable culverts, and tions of drain that cross people’s properties. in locations that are easy to access for cleaning However, incorporating drain design fea- and debris removal. tures that limit the need for maintenance is not To ensure that maintenance features are sufficient in itself. The rapid construction of correctly implemented, site supervision new houses after a project (figure 8.16a) and should be sufficiently rigorous in monitoring without attention to building controls, drain- construction details. For example, a contractor age, or good slope management practices also may decide to change the designed drain align- can limit the effectiveness of MoSSaiC project ment to work around problems on site. This drains. It is not always possible to ensure that can have the effect of rendering a drain or cul- adequate household drainage connections are vert more prone to blockage, uncontrolled planned for or made in such cases. This is flows, or damage postproject. equally true when houses are rebuilt in unsuit- Be aware of negative behavior that could able locations, such as on former or existing result from the construction of new drains or landslide areas (figure 8.16b). affect their functioning. For example, without Assign maintenance responsibility adequate access to waste disposal facilities, residents may use new drains to dump their In some cases, maintenance issues may not be garbage (figure 8.15a). Consider the effect of effectively addressed at the project conceptu- FI G U R E 8 .15  Unintended consequences of drainage interventions a. Roadside and hillside drains can become the b. This intercept drain, when completed, was location of choice for dumping garbage. regularly used by criminal groups for rapid access to and escape from adjoining properties. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   33 5 this would inevitably take the project F IG U R E 8 .1 6  Absence of building controls beyond the standard donor funding time can lead to inappropriate construction frame. • Institutional donors. Donor project audits repeatedly indicate the necessity of mainte- nance, but consider it the responsibility of the funding recipient to “own” the issue. As a consequence of this ambiguity, the responsibility for postproject maintenance of infrastructure in communities often remains ill defined (ILO 2005). This lack of ownership has an adverse effect on the medium- and a. In unauthorized communities, a house can be built in a few days; overall housing density can long-term effectiveness of such projects. increase significantly in a relatively short time MoSSaiC projects should therefore review period. practical ways for maintenance responsibili- ties to be assigned, which may include the fol- lowing: • Residents maintain roof guttering and household connections, clean drains adja- cent to their property, and report any dam- age to the implementing agency. • A community resident takes on the role of cleaning principle drains. • The government contracts with a commu- nity member to clean drains and inspect for damage. • The government contracts with a local company for drain cleaning. • The government contracts with the public b. Repair on a house built on a landslide site works agency to inspect drains for damage experiencing subsidence. and make repairs. Encourage structural inspections and community clean-up days alization stage. Part of the reason may lie in information given to different stakeholder Undertaking structural maintenance helps groups, which can result in ambiguity as to maximize construction design life. The struc- where responsibility for maintenance lies: tural integrity of drains, roof guttering, and household connections should be regularly • Communities. Residents may be told main- inspected by residents to identify—and tenance will be their responsibility post- report—cracks, leaks, general degradation, or project, but are not given a framework in damage that could compromise the effective- which to mobilize the community (and ness of the drainage in reducing landslide haz- secure real commitment) for such activity. ard (figure 8.17). • Government. Staff rarely include a mainte- If drains are not designed for easy mainte- nance strategy in project proposals, since nance (figure 8.18a) or maintenance responsi- 33 6    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E FI G U R E 8 .17  Importance of promoting community clean-up days Without regular cleaning, this drain became blocked only six months after it was built. bilities are not clearly agreed upon (fig- dynamic can be negative if they are not well ure 8.18b), drains can become blocked. supported by the community. This latter risk Encourage residents to be proactive in may be mitigated to some degree by encourag- organizing community clean-up days. These ing leading community residents (including events can be reasonably effective, but are MoSSaiC certified contractors) to take respon- rarely comprehensive; moreover, the social sibility for the events (figure 8.19). FI G U R E 8 .18  Debris traps should be installed and cleared regularly a. Debris blocking a drain that feeds a culvert under b. Debris trap installed by a community during a the road. When it rains heavily, the blocked culvert MoSSaiC project. Installed correctly, such traps causes the drain to overflow, and the steep road prevent drain blockage further downslope, but a becomes unsafe for pedestrians. A debris trap process for maintenance must be agreed upon. would prevent the culvert from becoming blocked. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   337 F IG U R E 8 .1 9  Debris collection and disposal a. MoSSaiC certified contractor takes the lead in b. Removing vegetation that may block the drain. organizing and participating in a community clean-up day. • Complex or multidisciplinary problems 8.7.2 The integrated behavior change need to be tackled strategy • Problem solving requires reflection, dia- Outcome mapping can be used to plan, moni- logue, communication, and teamwork. tor, and evaluate behavior change initiatives by focusing on (1) the perceptions and motiva- Outcome mapping uses a matrix to identify tions of specific actors (individuals, groups, the integrated strategy for achieving a specific and organizations), and (2) the environments project outcome—in this case, landslide risk that enable two-way learning, participation, reduction behavior change. Strategies and accountability. Outcome mapping can designed to achieve this outcome are divided overcome some of the issues of planning and into those targeted at specific individuals, measuring the effectiveness of behavior groups, or organizations and those focused on change strategies (Twigg 2007). It is applied the environment in which these stakeholders best in projects where the following pertains operate. Strategies are then subdivided as to (Jones and Hearn 2009): whether they cause change directly, persuade people, or provide support to achieve the out- • Stakeholders are working in partnership come. (See Earl, Carden, and Smutylo 2001 for • Capacity building is an important aspect of detailed guidelines.) the project Outcome mapping is a helpful tool for inte- grating communication and capacity-building • Understanding of social factors is critical strategies for encouraging behavioral change. • Knowledge needs to be promoted and pol- The distinction between stakeholders and icy influenced environments is similar to the three capacity 33 8    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E levels (individual, organizational, and institu- building strategies. Use the resulting matrix as tional/societal). The classification of strategies a means for monitoring and evaluating behav- as causal, persuasive, or supportive approxi- ioral change outcomes. mately mirrors the distinctions between vari- ous communication tools (one-way informa- tion sharing and two-way consultation and MILESTONE 8: dialogue) and between capacity-building tools Communication and capacity- (knowledge transfer, learning by doing, and learning networks). building strategies agreed upon Use table 8.15 as a guide for summarizing and implemented and integrating communication and capacity- TAB L E 8 .15  Mapping the integrated behavioral change strategy FOCUS EFFECT MoSSaiC EXAMPLE Causal • Initiate/fund MoSSaiC project • Cause a direct effect • Select MCU, government, and community task teams • Produce an output • Select communities • Prepare maps, studies, and reports Persuasive • Communication: dissemination of information, consulta- • Increase knowledge tion, demonstration sites Individuals, • Transfer technology/skills • Capacity building: formal training and workshops, on-the- groups, or job training • Expert driven and single purpose organizations • Change perceptions and intentions Supportive • Communication: community participation, dialogue • Sustained/frequent involvement that • Capacity building: participation, learning by doing, encourages learning/skill development certification • Based on support from instructors, supervisors, mentors, and peers • Produce self-sufficiency Causal • Agree on project steps, protocols, and collaborations • Change the physical or policy environment among government ministries • Incentives and rules • Implement physical works for landslide mitigation in communities Persuasive • Evidence for community-based landslide risk reduction Stakeholder • Disseminate information • Communication: mass media, advocacy, site visits environment • Change perceptions of wider public and • Capacity building: government task team interaction with decision makers community to build trust and empowerment Supportive • Community of practitioners • Develop collaborations and networks for • South-South collaboration, knowledge transfer, and user groups support Source: Earl, Carden, and Smutylo 2001. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   33 9 8.8 RESOURCES 8.8.1 Who does what CHAPTER TEAM RESPONSIBILITY ACTIONS AND HELPFUL HINTS SECTION Funders and • Use evidence of completed interventions to promote 8.4; 8.6.3 Promote behavioral change policy landslide risk mitigation makers Coordinate with the MCU • Understand risk perceptions 8.3; 8.4; 8.6 • Develop a communication strategy Clear communication to all stake- • Develop a clear message on the purpose of the interven- holders and to the wider public via tion, how it is to be undertaken, how community engage- appropriate media ment will occur, and realistic timelines Helpful hint: If project timelines are given, ensure they are met; failure to meet stated delivery times can lead to a lack of project support within the community. MCU • Identify on-site learning opportunities 8.6 Ensure that all stakeholders have the opportunity to build capacity • Recognize and give responsibilities to those who adopt the project and add value to it Postproject maintenance strategy • Develop a postproject maintenance strategy 8.7.1 • Map the behavioral change strategy and associated 8.7.2 Develop behavioral change strategy actions Coordinate with government task teams Community awareness • Hold community meetings to sensitize residents 8.5.1 • Discuss the show home concept within the community 8.5.2 Consider establishing a show home and seek to identify a home that could be used Develop project promotional material • Create posters and similar materials to raise awareness 8.5.3 Develop project media message • Engage the media, along with key community members 8.5.4 Government • Take opportunities to learn and apply new knowledge 8.6 task teams Capacity building and skills on site • Consider certification for key community individuals • Deliver facts to policy makers relating to the interven- 8.6.3 Communication with government tions that can be used to promote behavioral change • Seek to implement the postproject plan developed by 8.7.1 Postproject maintenance the MCU • With government task teams, discuss risk perceptions, 8.3.2 Awareness of risk perceptions project expectations, and factors that could moderate project uptake • Provide guidance on appropriate communication tools 8.5 • Engage in dialogue with government task teams and Involvement in two-way communica- Community other community residents, and attend meetings tion process task teams • Help select demonstration sites and show homes within the community • Participate in certification process and training courses 8.6.1 Adopt new practices for landslide risk where appropriate reduction • Follow guidelines on household drainage and drain 8.7.1 maintenance 3 4 0    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E 8.8.2 Chapter checklist SIGN- CHAPTER CHECK THAT: TEAM PERSON OFF SECTION 99Stakeholder perceptions and communication and capacity needs understood 8.4.2; 8.5 99Community representatives consulted about proposed communication and 8.5; 8.6 capacity-building activities 99House suitable as a community show home identified, if relevant 8.5.2 99Posters explaining project’s science created, if relevant 8.5.3 99Opportunity created for TV/radio interview at project start, if relevant 8.5.4 99Funds available to produce a short project documentary, if relevant 8.5.4 99Placing an article about the project in a local professional journal considered, if 8.5.5 relevant 99Communication strategy finalized 8.4; 8.5 99Capacity-building strategy developed 8.6 99Postproject maintenance strategy created 8.7.1 99Integrated behavioral change strategy reviewed by the MCU 8.7.2 99Milestone 8: Communication and capacity-building strategies agreed upon and 8.7.2 implemented 8.8.3 MoSSaiC certification • Recognition of individuals who have dem- onstrated a consistently high standard of The following provides guidelines for a contribution to a MoSSaiC project MoSSaiC certification process that could be adapted to suit local conditions. • Promotion and dissemination of best prac- tices Basis of the certification program • Stimulation of innovation and diversity in Certification entails evaluation of work per- MoSSaiC-related activities formed by a given individual on a MoSSaiC intervention. Consideration of an individual Benefits of certification for MoSSaiC certification is generally based By providing a standard for judgment of an on a recommendation from an MCU mem- individual engaged in a MoSSaiC project, the ber, a community member, or some other certification process publicly assures the com- person with sufficient knowledge of the role petence of the individual and provides a refer- the individual has played in the MoSSaiC ence of standing independent of educational project. provider or employer. Objectives of certification Assessment Certification of an individual associated To become certified, an individual must be with MoSSaiC-related activities is an impor- assessed on his or her demonstration of the tant element in assuring quality and the following: maintenance of standards. Certification • Effective communication with all rele- helps stakeholders, professional societies, vant stakeholders. Stakeholders may and potential employers identify specific include, but not be limited to, community individuals who meet the minimum criteria. members, government officials, MoSSaiC The primary objectives of the certification team personnel, and others engaged in the process are as follows: project in an official capacity. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 4 1 • Understanding of the impact of low-cost Assessments.” Science and Public Policy 33 (10): community-based landslide risk reduc- 713–28. tion within his or her particular spe- CADRI (Capacity for Disaster Reduction cialty. Examples of such specialties are Initiative). 2011. “Basics of Capacity low-cost drain construction, site survey Development for Disaster Risk Reduction.” United Nations, Geneva. work, site construction, and supervision. Crookall, D., and W. Thorngate. 2009. “Acting, • Delivery of high-quality work. Knowing, Learning, Simulating, Gaming.” Simulation Gaming 40: 8–26. • Taking the initiative in his or her area of specialization. Earl, S., F. Carden, and T. Smutylo. 2001. Outcome Mapping: Building Learning and Reflection into • Consistency of performance and commit- Development Programs. Ottawa: International ment throughout the project. Development Research Centre. http://web.idrc. ca/openebooks/959-3/. The above generic attributes recognize the broad nature of the potential skills an individ- FAO (Food and Agriculture Organization of the United Nations). 2004. “Participatory ual may possess and practice on a MoSSaiC Communication Strategy Design.” Document activity. ID 188865. http://www.fao.org/docrep/008/ y5794e/y5794e00.htm. 8.8.4 References FM Global. 2010. “Flirting with Disasters: Why ALNAP (Active Learning Network for Companies Risk It All.” http://www.fmglobal. Accountability and Performance in com/assets/pdf/P10168.pdf. Humanitarian Action). 2003. Participation by Crisis-Affected Populations in Humanitarian Gaillard, J. C., and J. Mercer. 2012. “From Actions—A Handbook for Practitioners. London: Knowledge to Action: Bridging Gaps in Disaster Overseas Development Institution. http://www. Risk Reduction.” Progress in Human Geography alnap.org/publications/gs_handbook/gs_ doi:10.1177/0309132512446717. handbook.pdf. GNDR (Global Network of Civil Society Benson, C., and J. Twigg. 2007. “Tools for Organizations for Disaster Reduction). 2011. If Mainstreaming Disaster Risk Reduction: We Do Not Join Hands: Views from the Guidance Notes for Development Frontline—Local Reports of Progress on Organisations.” ProVention Consortium, Implementing the Hyogo Framework for Action, Geneva. with Strategic Recommendations for More Effective Implementation. Teddington, UK: Bessette, G. 2004. “Involving the Community: A GNDR. Guide to Participatory Development Communication.” Southbound in association Höppner, C., M. Buchecker, and M. Bründl. 2010. with the International Development Research “Risk Communication and Natural Hazards.” Centre, Penang, Malaysia. Cap Haz-Net. WP5 Report, Berne, Switzerland. Bohm, D. 1996. “On Dialogue.” Schouten & IDRC (International Development Research Nelissen, Zaltbommel, the Netherlands. http:// Centre). 2012. “Developing a Communications sprott.physics.wisc.edu/chaos-complexity....../ Strategy.” http://web.idrc.ca/uploads/user- dialogue.pdf. S/11606746331Sheet01_CommStrategy.pdf. Bull-Kamanga, L., K. Diagne, A. Lavell, E. Leon, F. IFRC (International Federation of Red Cross and Lerise, H. MacGregor, A. Maskrey, M. Meshack, Red Crescent Societies). 2008. “VCA Training M. Pelling, H. Reid, D. Satterthwaite, J. Guide: Classroom Training and Learning-by- Songsore, K. Westgate, and A. Yitambe. 2003. Doing.” IFRC, Geneva. “From Everyday Hazards to Disasters: The —. 2010. Advocacy for Disaster Risk Reduction Accumulation of Risk in Urban Areas.” Training Course: Facilitator’s Guide. http:// Environment and Urbanization 15 (1): 193–203. drrinsouthasia.net/downloads/Publications_ Burgess, J., and J. Chilvers. 2006. “Upping the Case_Studies/IFRC/Advocacy%20for%20 Ante: A Conceptual Framework for Designing DRR%20Trg.%20Kit/Facilitators%20 and Evaluating Participatory Technology Guide%20Advocacy%20Trg.%20Kit.pdf. 3 42    C H A P T E R 8 .   E N CO U R A G I N G B E H AV I O R A L C H A N G E ILO (International Labour Organization). 2005 Paton, D. 2003. “Disaster Preparedness: A Social- “Community Contracting and Organisational Cognitive Perspective.” Disaster Prevention and Practices in Rural Areas: A Case Study of Management 12: 210–16. Malawi.” http://www.ilo.org/wcmsp5/groups/ Rioja, F. K. 2003. “Filling Potholes: Macroeconomic public/@ed_emp/@emp_policy/@invest/ Effects of Maintenance versus New documents/publication/wcms_asist_8030.pdf. Investments in Public Infrastructure.” Journal Jones, H., and S. Hearn. 2009. “Outcome Mapping: of Public Economics 87 (9–10): 2281–304. A Realistic Alternative for Planning, Monitoring Twigg, J. 2007. “Characteristics of a Disaster and Evaluation.” Overseas Development Resilient Community: A Guidance Note.” Institute, UK. http://www.odi.org.uk/ https://practicalaction.org/docs/ia1/ resources/docs/5058.pdf. community-characteristics-en-lowres.pdf. Kunreuther, H., and M. Useem. 2010. “Principles UNU (United Nations University). 2006. and Challenges for Reducing Risks from “Landslides. Asia Has the Most; Americas, the Disasters.” In Learning from Catastrophes, ed. Deadliest; Europe, the Costliest; Experts Seek H. Kunreuther and M. Useem. Upper Saddle Ways to Mitigate Landslide Losses; Danger Said River, NJ: Wharton School Publishing. Growing Due To Climate Change, Other Luft, J., and H. Ingham. 1950. “The Johari Window, Causes.” News Release MR/E01/06/rev1. a Graphic Model of Interpersonal Awareness.” UNDP (United Nations Development Programme). In Proceedings of the Western Training 2012. Communicating for Results: Reaching the Laboratory in Group Development. Los Angeles. Outside World. http://web.undp.org/comtoolkit/ Lundgren, R. E., and A. H. McMakin. 2009. Risk reaching-the-outside-world/outside-world- Communication—A Handbook for tools.shtml. Communicating Environmental, Safety, and UNEP (United Nations Environment Programme). Health Risks. Hoboken, NJ: Wiley. 2002. Capacity Building for Sustainable Malamud, B. D., and D. Petley. 2009. “Lost in Development: An Overview of UNEP Translation.” Public Service Review: Science and Environmental Capacity Development Activities. Technology 2: 164–67. www.unep.org/Pdf/Capacity_building.pdf. Mansuri, G., and V. Rao. 2003. Evaluating UNICEF. 2008. “Conference on Community-based Community-Based and Community-Driven Disaster Risk Reduction.” November 26–28, Development: A Critical Review of the Evidence. Kolkata. www.unicef.org/india/Conference Development Research Group. Washington, CommunitybasedDisasterRiskReductionreport. DC: World Bank. pdf. Maskrey, A. 1992. “Defining the Community’s Role UNISDR (United Nations Office for Disaster Risk in Disaster Mitigation.” Appropriate Technology Reduction). 2004. “Hyogo Framework for Magazine 19 (3). http://practicalaction.org/ Action 2005–2015: Building the Resilience of practicalanswers/product_info.php?products_ Nations and Communities to Disasters.” id=214. UNISDR, Geneva. http://www.unisdr.org/wcdr. McNabb, M., and K. Pearson. 2010. “Can Poor Wisner, B. 2009. “Local Knowledge and Disaster Countries Afford to Prepare for Low- Risk Reduction.” Keynote presentation at the Probability Events?” In Learning from Side Meeting on Indigenous Knowledge, Catastrophes, ed. H. Kunreuther and M. Useem. “Global Platform for Disaster Reduction,” Upper Saddle River, NJ: Wharton School Geneva, June 17. Publishing. World Bank. 2010. Development and Climate Mefalopulos, P. 2008. Development Communication Change. World Development Report. Sourcebook—Broadening the Boundaries of Washington, DC: World Bank. Communication. Washington, DC: World Bank. —. 2011. “Mainstreaming Adaptation to Climate Mefalopulos, P., and C. Kamlongera. 2004. Change in Agriculture and Natural Resources Participatory Communication Strategy Design: A Management Projects. Engaging Local Handbook. Southern African Development Communities and Increasing Adaptive Community, Centre of Communication for Capacity.” Guidance Note 2 http://siteresources. Development. Rome: Food and Agriculture worldbank.org/EXTTOOLKIT3/ Organization of the United Nations. Resources/3646250-1250715327143/GN2.pdf. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   3 43 “‘What gets measured is what counts.’ This focus on outcomes helps policymakers choose the best options for serving poor people. It helps the providers know when they are doing a good job. And it helps clients judge the performance of both.” —World Bank, Making Services Work for Poor People (2004, 108) CHAPTER 9 Project Evaluation 9.1 KEY CHAPTER ELEMENTS 9.1.1 Coverage This chapter provides a framework for MoSSaiC for an evidence base for ex ante landslide risk (Management of Slope Stability in Communi- reduction. The listed groups should read the ties) project evaluation and highlights the need indicated chapter sections. AUDIENCE CHAPTER F M G C LEARNING SECTION    Importance of project evaluation 9.2   Development of key performance indicators 9.4–9.5 F = funders and policy makers  M = MoSSaiC core unit: government project managers and experts  G = government task teams: experts and practitioners  C = community task teams: residents, leaders, contractors 9.1.2 Documents CHAPTER DOCUMENT TO BE PRODUCED SECTION Key performance indicator list for immediate project outputs 9.4 Key performance indicator list for medium-term project outcomes 9.5 An agreed-upon evaluation framework 9.4, 9.5 345 9.1.3 Steps and outputs STEP OUTPUT 1. Agree on key performance indicators (KPIs) for immediate project outputs List of project • Develop and agree on a list of KPIs that comply with donor/government needs output KPIs for and MoSSaiC output measures evaluation 2. Agree on KPIs for medium-term project outcomes List of project • Develop and agree on a list of project outcome measures that allow evalua- outcome KPIs for tion of landslide hazard reduction, project costs, and behavioral change evaluation 3. Undertake project evaluation Project evaluation • Agree on responsibilities for short- and medium-term data collection and the report project evaluation process • Carry out the evaluation 9.1.4 Community-based aspects continuation, or scaling-up of a given project or policy. The chapter outlines how community mem- bers can contribute to postproject evaluation Evaluation of a MoSSaiC project provides and the evidence base for community-based the evidence base for ex ante landslide risk landslide hazard reduction. reduction (which is one of the three founda- tions of MoSSaiC) by demonstrating whether community-based landslide risk reduction 9.2 GETTING STARTED works and pays, and what the most appropri- ate practices and policies are. This evidence 9.2.1 Briefing note base comprises three levels and time frames of project evaluation information: Evaluation aims • Standard key performance indicators Project evaluation aims to “determine the rel- (KPIs). Have the requirements of the evance and fulfillment of objectives, develop- funders and other stakeholders been met? ment efficiency, effectiveness, impact and sus- tainability” (OECD 2002, 21). Evaluation is • Short-term MoSSaiC outputs and KPIs. carried out both during and after projects (for- Have MoSSaiC milestones been met using matively and summatively, respectively) as fol- appropriate community- and science-based lows (World Bank 2007): methods? • Formative evaluations focus on project • Medium- and longer-term MoSSaiC out- implementation and improvements, regard- comes. Are there continuing benefits from less of whether the assumed operational the project in terms of reduced landslide logic corresponds to actual operations and hazard and adoption of effective urban what immediate consequences each imple- landslide risk reduction practices and poli- mentation stage produces. cies by communities and government (i.e., behavioral change)? • Summative evaluations focus on out- comes and impacts at the end of the proj- In addition to these three levels or time ect (or after a particular project stage) to frames, MoSSaiC project evaluations should determine the extent to which antici- consider three categories of effectiveness— pated outcomes were produced (the con- technical and physical (reducing the hazard), sequences and results of the project)— cost, and behavioral change (including risk enabling an assessment of the creation, reduction awareness and capacity). 3 4 6    C H A P T E R 9.   P RO J E C T E VA L U AT I O N Evaluation is of interest to the intended based on technical efficiency (inputs, activi- beneficiaries in communities; government and ties, and immediate outputs). Medium- and community task teams participating in the long-term outcome and impact evaluation is project; the MoSSaiC core unit (MCU) and the seldom built into risk reduction projects agency with a contractual or legal responsibil- (World Bank 2003); and, in many cases, ade- ity to report on results to the funding source; quate baseline data are not collected. This sit- development funders, policy makers, and uation has two consequences: first, it is diffi- practitioners; and scientific researchers. cult to find adequate measures of success on which a project may be evaluated after just Designing the evaluation process two or three years following completion. Sec- Project managers frequently view audits as ond, longer-term project impact evaluations complex, time consuming, expensive, and not are rarely, if ever, instigated (Benson and always focused on answering the right ques- Twigg 2004). tions (Baker 2000). In this regard, Easterly Project evaluation design should be driven (2002, 53) notes that by project objectives in order to determine …vast sums of money and unbelievable levels whether short-term outputs are effective in of technical complexity have been expended generating medium-/long-term outcomes, to make Monitoring and Evaluation…into a and whether those outcomes are consistent functional tool… Moreover, bureaucracies with stakeholder needs and project objectives can manipulate quantitative indicators of (McDavid and Hawthorn 2005) (figure 9.1). performance to achieve “success” without The MoSSaiC evaluation process is of great- real quality improvements. (This is different from evaluation for the sake of learning les- est potential benefit if, as with the project sons for future practice.) delivery mechanism, its scope is locally formu- lated. It should be designed with objectives, This form of project evaluation tends to outputs, and outcomes in mind and to enable lead to a short-term view of project success lessons to be learned for future practice (East- FI G U R E 9.1  Links between project objectives and overall project success social value of outcomes cost-benefit analysis/net social value needs environment social value actual outcomes of inputs effectiveness (1) program objectives inputs activities outputs relevance technical efficiency cost-effectiveness effectiveness (2) adequacy Source: McDavid and Hawthorn 2005. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   3 47 erly 2002). This evidence base is important if • Costs incurred in reducing the landslide the perceptions of individuals, governments, hazard (in conjunction with the outcomes and major international funding agencies are of the technical/physical evaluation) to be changed regarding community-based • Costs of not undertaking the intervention landslide risk reduction. (potential cost of a landslide) Evaluating technical and physical effectiveness • Proportion of project money spent on con- (landslide hazard reduction) struction materials and labor. MoSSaiC employs scientific methods to Evaluation of capacity-building, awareness, and assess landslide hazard and drainage issues behavioral change affecting communities and to determine if improved drainage will increase slope stabil- The emphasis on community engagement and ity. Drainage interventions are then designed the development of a government team to on this basis. An evaluation of a MoSSaiC design and implement landslide risk reduction intervention should demonstrate the level to means that MoSSaiC can build capacity. This which landslide hazard has potentially been capacity building may occur through hands- reduced. Hazard reduction can be deter- on experience, the use and development of mined through existing skills, or some form of training. Addi- tionally, the project may employ (or attract) • the use of slope stability calculations and the media and demonstrate good slope man- models, agement practices to the wider public. The • observations relating to rainfall events and aim is to generate a culture of awareness of the effectiveness of drains, landslide causes and of appropriate measures that can reduce this hazard. Over time, with • observations relating to subsequent slope the ongoing implementation of projects in dif- stability, and ferent communities, a degree of behavioral • comments from residents. change will become embedded in the approach to landslide risk. Evaluating cost-effectiveness To evaluate the capacity-building and A central premise of MoSSaiC is that it is often behavioral change achievements of a MoSSaiC more cost-effective to reduce landslide hazard project, the following indicators are relevant: in communities than it is for a government to • Involvement of key government technical respond to a landslide and for the community and managerial staff to recover from one (Anderson and Holcombe 2006). This cost-effectiveness extends to the • Involvement of community contractors, method of landslide hazard reduction—the residents, and leaders appropriate use of slope surface drainage to • Training of government staff, contractors, reduce the landslide hazard for as many house- or community leaders on site and in the holds as possible. The use of existing govern- classroom ment personnel and the engagement of con- • Adoption of good slope management and tractors from the community should maximize landslide hazard reduction practices and the proportion of project money spent on the policies by government in subsequent inter- ground. ventions Evaluation of the cost-effectiveness of a MoSSaiC intervention involves monetizing all • Adoption of good slope management and the costs and benefits associated with the proj- landslide hazard reduction practices by ect. In that context, three core costs are to be communities and contractors after the determined: project is completed 3 4 8    C H A P T E R 9.   P RO J E C T E VA L U AT I O N • Media uptake and presentation of the 9.2.3 Risks and challenges approach Evaluation seen as low priority • Comments from project participants. Project evaluation is rarely seen as a priority 9.2.2 Guiding principles during project implementation, and record- keeping for KPIs or evaluation purposes fre- The following guiding principles apply in proj- quently takes a backseat to more immediate ect evaluation: and pressing issues. But without project evalu- ation, performance and progress cannot be • Agree on MoSSaiC project evaluation measured; data collection to this end is vital. A objectives with stakeholders at the start of member of the government task teams must be the project. Make sure KPIs directly relate given responsibility for coordinating project to these objectives over short, medium, and evaluation in terms of securing agreement on longer time frames. KPIs, developing a template for recording rel- • Where possible, integrate the collection of evant data, and recording the data in a timely project performance data into the project manner. process rather than creating separate (or Sustaining project data capture over the duplicate) activities. For example, data medium term is another challenging issue, and collected during community selection, must be addressed so that the true project detailed community mapping, landslide impact can be demonstrated. It may be appro- hazard assessment, and drainage design priate to initiate a formal assessment of ongo- (landslide hazard, exposure, and vulnera- ing impact on government capacity and the bility) can also be used as baseline data for extent of behavioral change. Other data relat- evaluating postproject changes in land- ing to the physical effectiveness of the mitiga- slide risk and surface water flows. Simi- tion measures should be collected as and when larly, capacity assessments, studies of risk major rainfall events occur months—or even perception, and the behavior change strat- years—after project completion. egy map (discussed in chapter  8) can be Responsibility for acquiring and maintain- revisited after the project to evaluate ing postproject evaluation data might best be changes. given to and overseen by an agency with an existing mandate for disaster risk manage- • Establish responsibilities for project evalu- ment, community vulnerability reduction, or ation both during and after the project. The geological and geotechnical surveys, or with a responsibility for medium- and long-term local university research program. postproject evaluation (or monitoring) may need to reside with a local agency that Top-down evaluation already has a mandate or research program Development and disaster risk reduction for disaster risk assessment and manage- (DRR) project evaluations remain predomi- ment. nantly top down, designed to provide informa- • Ensure the collection and evaluation of tion to headquarters staff and donors. What is project performance data are transparent certain is that and open to independent or external audit- evaluations need to go far beyond “bureau- ing. Adhere to funder and government safe- cratic” reports presenting financial accounts guards for evaluation and monitoring. and “physical” achievements of projects, Invite independent review of the project such as those required by many funding orga- evidence base to establish credibility and nizations. In fact, this kind of reporting tends learn lessons for future practice. to encourage and allow precisely the dis- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 4 9 torted presentations of achievements that 9.3 DATA REQUIREMENTS FOR emphasize successes and minimize failures PROJECT EVALUATION (Platteau 2004, 243). Impediments to data collection KPIs are metrics, or data, used for project eval- uation that relate project objectives and inputs The time and resources allocated to project to the resulting outputs and outcomes. evaluations are usually very limited, leading to • Inputs. Inputs are the funds, time, and overemphasis on selective field evidence. Data resources required for the project. can be further skewed by the methods used and perceptions of those involved in both • Outputs. Outputs are the immediate results acquiring and providing the data. For example, of project implementation such as number “agency evaluation teams dominated by exter- of persons employed, meters of drain con- nal specialists—often men—appear to be com- structed, or number of houses with roof mon” (Benson and Twigg 2004, 115). guttering installed. Organizations may not want to provide infor- • Outcomes. Outcomes are the longer-term mation that shows that a program was ineffec- results of the project such as reduction in tive. Nonetheless, the MCU should promote the landslide probability, reduced cost of land- importance of evaluation regardless of potential slides, or improvements in slope manage- outcome; as the World Bank (2004, 106) notes: ment practice. There are impediments to collecting such information [data and information to facili- 9.3.1 MoSSaiC project evaluation data tate the evaluation]. Provider organizations often do not want to acknowledge their lack To achieve a holistic evaluation of the MoSSaiC of impact (even if it does not affect their pay program, the MCU should develop a plan for directly), but knowing when things are not acquiring KPI data and evidence relating to working is essential for improvements. Fur- three categories—technical/physical effective- ther, it is necessary to know not just what ness, cost-effectiveness, and behavioral change works but also why—to replicate the program and increase the scale of coverage. (including risk reduction awareness and capacity)—over two postproject time frames: 9.2.4 Adapting the chapter blueprint to • At project completion (outputs) existing capacity • Over the medium term—three to five years Use the capacity scoring matrix opposite to after project completion (outcomes). assess the capacity of the MCU and govern- Data within these categories (table 9.1) ment task teams to carry out evaluation during facilitate construction of three KPI clusters, and immediately after the project. Identify introduced in sections 9.4 and 9.5: potential capacity for medium- to long-term postproject evaluation of outcomes. • Typical donor-focused KPIs. The MCU should ascertain if there are any donor KPI 1. Assign a capacity score from 1 to 3 (low to requirements for the MoSSaiC project high) to reflect existing capacity for each of (table 9.2). the elements in the matrix’s left-hand col- umn. • Detailed MoSSaiC KPIs for project out- puts. The MCU should create an agreed- 2. Identify the most common capacity score as upon list of output KPIs relevant to the spe- the overall capacity level. cific project (table 9.3). 3. Adapt the chapter blueprint in accordance with this overall capacity level (see guide at • KPIs for MoSSaiC project outcomes. The the bottom of the opposite page). MCU should create a list of outcome KPIs 3 5 0    C H A P T E R 9.   P RO J E C T E VA L U AT I O N EXISTING CAPACITY SCORE CAPACITY ELEMENT 1 = LOW 2 = MODERATE 3 = HIGH Experience of project Limited awareness of project Project evaluation not Value of project evaluation evaluation in previous DRR or evaluation requirements and routinely undertaken, but well recognized and under- community-based projects methods some experience in require- taken on a routine basis ments and methods Level of community participa- Low level of community Good level of community High level of community tion and ownership of project engagement; little apparent engagement and some interest engagement; willingness to interest in evaluation in taking part in project output evaluate and monitor project evaluation outputs and outcomes Existing precedent within No precedent within govern- Postproject evaluations Government agency or unit government for postproject ment for postproject undertaken on ad hoc basis responsible for evaluation and evaluation evaluation monitoring of DRR projects Culture of data acquisition for No culture of data acquisition Occasional attempts at Relevant databases systemati- project evaluation for project evaluation systematic data acquisition but cally maintained; consultants no coordinating agency engaged to report on impact of major projects Experience with cost-effec- No previous relevant experi- Some examples of cost-effec- Previous experience undertak- tiveness and cost-benefit ence in undertaking cost- tiveness analysis but not in the ing both cost-effectiveness analyses for DRR and commu- effectiveness or cost-benefit context of community-based and cost-benefit analyses nity-based projects analyses or DRR projects relevant to MoSSaiC Project safeguards Documented safeguards need Documents exist for some Availability of documented to be located; no previous safeguards safeguards from all relevant experience in interpreting and agencies operating safeguard policies CAPACITY LEVEL HOW TO ADAPT THE CHAPTER BLUEPRINT 1: Use this chapter The MCU needs to strengthen its resources prior to designing and implementing the project evaluation. This in depth and as a might involve the following: catalyst to secure • Using this book to develop a brief training course for MCU and government task team members on the support from rationale for MoSSaiC project evaluation other agencies as appropriate • Integrating project evaluation data acquisition into the community participation process • Searching within government for expertise and data collection processes relevant to MoSSaiC project evaluation • Developing a suitable cost-effectiveness evaluation method 2: Some elements The MCU has strength in some areas, but not all. Those elements that are perceived to be Level 1 need to be of this chapter addressed (as above). Elements that are Level 2 will require strengthening, such as the following: will reflect current • Negotiating the collection of relevant data from other government departments practice; read the remaining • Discussing project outputs and outcomes at community meetings and establishing a postproject evalua- elements in depth tion plan and use them to • Confirming where responsibility for postproject evaluation lies within the government and how it will be further strengthen undertaken capacity 3: Use this chapter The MCU is likely to be able to proceed using existing proven capacity. It would be good practice nonethe- as a checklist less for the MCU to document relevant experience with project evaluation and related safeguards. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 5 1 TA BLE 9.1  Data needed to evaluate outputs and outcomes by category of evaluation EVALUATION FOR PROJECT COMPLETION FOR MEDIUM-TERM OUTCOMES AND CATEGORY OUTPUTS IMPACT Community slope feature map, slope Not applicable process zone map, prioritization matrix, and final drainage plan Hazard assessment (rainfall recurrence Slope stability performance (slope Technical/ intervals, slope stability analysis simula- monitoring, landslide inventory, rainfall physical tions) data) Drainage design and construction Drain performance and maintenance (observed) Improved community environment, environmental health, and other physical benefits (resident feedback) Total cost of intervention Actual or potential cost of landslide (for use in cost-benefit analysis) Budget spent on the ground Ongoing use of local personnel for design Cost and construction (observed) Other benefits to community (capable of being monetized), both short and long term (for use in cost-benefit analysis) Government personnel involved/trained Ongoing use and adoption of experience, Capacity, Contractors involved good practice, and skills (observed/ awareness, stakeholder feedback) and behavioral Community residents involved change Media uptake Peer-reviewed professional papers written on projects and associated mechanisms for data collec- Before the project tion and analysis (table 9.4). During the community mapping process 9.3.2 Community knowledge and project (chapter 5), the government task teams should evaluation data have recorded indications given by residents Communities can provide valuable informa- on the maximum water levels experienced tion for all three categories of MoSSaiC project during times of heavy rainfall, areas of stag- evaluation: nant water, flooding of property, previous landslide impact on property, and other issues • Contributing local knowledge of slope fea- to be addressed in designing interventions tures before the intervention (chapter 5) (figure 9.2). • Monitoring structural cracks, water table After the project levels, and drain performance after the intervention (sections 9.5.3, 9.5.4, and 9.5.5) After the project, first-hand comments and observations should be sought from residents • Observing and commenting on conditions on the impact of interventions to supplement in the community before and after an inter- other evidence of project outcomes (sec- vention (sections 9.5.6 and 9.5.7). tion 9.5). Of particular value is information on These and similar observations are a major the depth of flow in the constructed drains fol- contribution to evaluation and performance lowing heavy rainfall (figure 9.3). measures, and community engagement is a Seek and record residents’ views, such as prerequisite to determining the project’s holis- the following, that reflect their post-interven- tic benefits. tion experiences: 3 52    C H A P T E R 9.   P RO J E C T E VA L U AT I O N FI G U R E 9.2  Residents showing issues to be F IGUR E 9. 3  Maximum observed flow level addressed by MoSSaiC interventions in a MoSSaiC drain during Hurricane Tomas a. Resident indicating maximum observed flood levels prior to intervention. • “The rain was heavy, heavy but the slope held—there were no landslides at all” (com- munity resident) • “The health of children has improved as there is less stagnant water” (community resident). b. Resident in area of slope instability adjacent to his home prior to a MoSSaiC intervention. Use pre- and postproject questionnaires to quantify or monetize benefits (and problems) resulting from the project; see section 9.7.5. Look for evidence of increased awareness and understanding of landslide causes and solutions and changes in slope management practices; see chapter 8 and section 9.5.8. 9.4 PROJECT OUTPUTS: EVALUATING IMMEDIATE IMPACT 9.4.1 Typical key performance indicators c. Resident indicating occurrence of stagnant water before intervention. At the start of a project, the implementing agency, the government, and—potentially—the donor agency need to agree on a set of appro- • “If it were not for the MoSSaiC drains, peo- priate KPIs. KPI specification is typically a ple would have perished” (government offi- donor requirement for funds awarded and will cial) tend to focus on immediate, easily identifiable project outputs rather than longer-term out- • “The drains worked perfectly and there comes. This focus enables the progress and were no landslides” (community resident) “success” of a project to be tracked during CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 5 3 implementation and at completion. Table  9.2 major donors (including the World Bank) presents a sample set of KPIs that may be have always made provisions for them (World Bank 2004, 106). selected for a MoSSaiC project. 9.4.2 Output key performance indicators The MCU should assemble a list of for MoSSaiC projects MoSSaiC-specific project outputs to be While typical KPIs can provide a checklist for reported on at the completion of an interven- project progress and completion, it is impor- tion (table 9.3). These outputs will probably be tant to recognize what is actually happening more comprehensive than the potential KPIs on the ground. Standard outputs such as those requested by donors. listed in table 9.2—a map, a report, the number of personnel involved—do not tell the full story. Indicators need to be adopted that allow 9.5 PROJECT OUTCOMES: evaluation of MoSSaiC’s effectiveness in using EVALUATING MEDIUM-TERM science- and community-based methods (out- PERFORMANCE puts) to reduce landslide hazard in the most vulnerable communities (outcomes): Measures beyond the immediate project com- Good evaluation is the research necessary to pletion benefits (outputs) need to be consid- assign causality between program inputs and ered in order to achieve a holistic picture of real outcomes. It should be directed at the project performance. Possible indicators of full impact of programs—not just the direct benefits accruing over one to five years after outputs of specific projects. But few evalua- project completion (outcomes) are given in tions have been done well, even though most table 9.4. TA BLE 9. 2  Typical donor-focused key performance indicators for project outputs EVALUATION CATEGORY TYPICAL KPI OUTPUT For each community Community-based mapping of slope features Community slope feature map relating to landslides and slope processes Assessment of landslide hazard processes Slope process zone map, prioritization matrix, scientific report Technical/ Design of an appropriate drainage intervention Final drainage plan physical Generation of work packages and contracts Contracts for community-based contractors and laborers Construction of drains Drains Installation of household gray water and roof Roof guttering, etc. water connections For the project Cost of construction materials and labor Monetary value Cost Cost of other items in project budget Monetary value Government personnel able to implement Number of personnel in teams landslide hazard reduction in communities Capacity, Contractors from communities employed in Number of contractors and laborers awareness, construction of drains for landslide hazard and behavioral reduction change Community residents aware of good slope Days spent in community, number of management practices meetings 3 5 4    C H A P T E R 9.   P RO J E C T E VA L U AT I O N TAB L E 9. 3  Detailed MoSSaiC key performance indicators for project outputs EVALUATION CATEGORY MoSSaiC KPI OUTPUT Use of scientific methods for assessing landslide Scientific rationale and model hazard results Use of appropriate engineering methods for Design drawings and calculations designing drains Drain construction and supervision of works to an Good construction practices, Technical/ acceptable standard good-quality drains—e.g., no leaks physical Acceptable standard of connection of households or uncontrolled flows to drains Improvement of drainage and slope stability issues Number of houses/people for whole community (not just a few houses) benefiting directly and indirectly Improvement in water supply to most vulnerable Number of water tanks installed households Benefit to community in terms of employment Number of person/weeks of employment Proportion of budget spent on construction Percentage of budget materials and labor Cost Final project costs in relation to original budget Percentage of budget Comparison of project cost with potential Project cost as percentage of community relocation costs potential community relocation cost Government personnel, contractors, or community Number receiving certification members receiving certification for involvement and skills Capacity, Evidence of residents providing free project input In-kind contribution awareness, in terms of design, construction, and materials and behavioral change Evidence of uptake of good slope management Independent and appropriate practices and self-help in communities installation of drains/gutters, etc. Evidence of media interest and promotion Number of interviews, posters, news items, etc. 9.5.1 Observed slope stability • poor maintenance or disconnection of household roof guttering and gray water MoSSaiC interventions are designed to reduce pipes, and the risk of rainfall-triggered landslides. How- ever, it is difficult to establish what would have • construction of new houses with no con- happened to a particular slope if a drainage nection to drains. intervention had not been carried out; this is the counterfactual problem in arguing for risk Therefore, evidence of postproject slope reduction. stability must be collected, particularly in rela- Because such interventions cannot com- tion to high levels of rainfall, but also with a pletely eliminate landslide hazard, there is the view to other causes as an indication of the residual likelihood of instability on such slopes effectiveness (or limitation) of each interven- that may be triggered by tion. • more extreme rainfall events, Landslides in adjoining areas • poor drain maintenance (blocked, over- Areas immediately adjacent to intervention flowing, or broken drains), areas can serve as a control group of slopes, CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 5 5 TA BLE 9.4  MoSSaiC key performance indicators for project outcomes EVALUATION CATEGORY MoSSaiC KPI OUTCOME (EVIDENCE BASE) Slope stability during and after high rainfall • Observed slope stability (section 9.5.1) events • Rainfall data and landslide inventory (section 9.5.2) • Household crack monitoring (sec- Technical/ tion 9.5.3) physical • Water table monitoring (sections 9.5.2 and 9.5.4) Drain performance • Recorded drain flows (section 9.5.5) Benefits to the community in terms of • Observations, community feedback, improved community environment formal survey (section 9.5.6) Actual or potential costs of a landslide • Cost-benefit analysis (section 9.5.7) Cost Benefits to the community in terms of employment, improved access, reduced damage to houses Capacity, Ongoing use of local personnel for design • Observed good/bad slope management awareness, and construction practices and behavioral Ongoing use and adoption of experience, • Stakeholder feedback change good practice, and skills • Formal survey (section 9.5.8) Evidence base used to infer what might have happened if an intervention had not been undertaken. For The following information should be recorded example, following heavy rainfall, an area in over a one- to five-year period after the project which a MoSSaiC intervention had been com- ends: pleted remained stable; in contrast, the adjoin- ing hillside area 50 m away experienced a • The observed stability of the drainage inter- major landslide, resulting in the loss of houses vention area (the community), during and and relocation of families (figure 9.4). after rainfall events that would have been F IG U R E 9.4  Landslide in an area immediately adjacent to a slope successfully stabilized by a MoSSaiC intervention 3 5 6    C H A P T E R 9.   P RO J E C T E VA L U AT I O N expected to (or actually did) trigger land- event, this demonstrates the degree of pro- slides in the region/country tection provided by the drainage interven- tion. • The effect of such rainfall events on the sur- Figure 9.5 illustrates the return periods for rounding/adjacent hillside different cumulative rainfalls for a location in • Any other evidence of slope stability/insta- St. Lucia in October 2008. As the table shows, bility within the drainage intervention area while the 24-hour rainfall on October 11 had a and the surrounding/adjacent hillside that low return period, the 15-day cumulative rain- may be the result of physical or human fac- falls for each of the days in the period Octo- tors other than rainfall. ber 10–21 amounted to a > 1-in-50-year event. Sources of information include the follow- The figure plots the accumulated rainfall totals ing: to obtain a clear idea of the respective return periods. A number of landslides were trig- • Government. Agencies will typically be gered in the period when the cumulative contacted by communities when landslides 15-day rainfalls exceeded the 1-in-50-year occur and will send engineers or techni- event; notably, no landslides were triggered on cians to inspect or remedy the damage. hillsides where drainage interventions had • Meteorological agencies. These can pro- been completed. vide rainfall data and associated recurrence Estimate before and after recurrence interval interval estimates. Using data related to specific return period • Communities. Residents usually have a rainfall events gives an indication of interven- sound and detailed knowledge of the effects tion performance (table 9.5). of rainfall events. A slope stability back-calculation can be • Photographs and measurements of the used to estimate what the effect of the rainfall physical disturbance. These should be event would have been in the absence of drain taken as close to the time of the event as construction. The results can also be com- possible, before vegetation growth masks pared to any calculations undertaken prior to the landslide, or residents begin to recon- the drainage intervention as part of the land- struct houses on the failed material. slide hazard assessment (chapter 6). 9.5.2 Rainfall and slope stability Additional rainfall information information Satellite imagery relating to major rainfall The following information should be obtained events such as hurricanes is a useful data over a one- to five-year time frame: source to accompany quantitative rainfall data, especially if there are associated calculations • Rainfall intensities, volumes, and durations of rainfall intensity (figure 9.6). Hurricanes for events that would be expected to (or can cause substantial long-term damage to actually) trigger landslides in the region/ infrastructure and set economies back many country years, particularly those of small island devel- • Rainfall intensities, volumes, and durations oping states. Associating hurricane tracks and for hurricanes and tropical storms or events rainfall intensities with the effectiveness of that have > 1-in-1-year return periods implemented project elements, such as hurri- cane strapping and drainage, is useful for Calculate rainfall magnitude and frequency benchmarking medium-term outcomes. Detailed rainfall intensities, volumes, and Evidence base durations for major storms are needed to esti- mate the return period of an event. If a slope Collect the following data to assess the effec- has proved stable for a particular rainfall tiveness of landslide hazard mitigation proj- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 5 7 F IG U R E 9. 5  Daily and cumulative rainfall with associated return periods for a location in St. Lucia, October 2008 500 450 400 350 rainfall (mm) 300 250 200 150 100 50 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 October 2008 cumulative observed rainfall 24 hours 5 days 7 days 15 days DATES WHEN CUMULATIVE OBSERVED RAINFALL EVENT THRESHOLDS RAINFALL > THRESHOLD EVENT 1-in-5-year 5-day event each day: October 10–13 1-in-5-year 7-day event each day: October 10–15 1-in-5-year 15-day event each day: October 7–24 1-in-50-year 15-day event each day: October 11–21 except October 19 ects for major storm events affecting countries too common in vulnerable communities with or whole regions: unauthorized housing, as residents construct homes in conditions of marginal slope stabil- • Rainfall data and recurrence interval rain- ity, using limited technical equipment, no spe- fall event data from the relevant meteoro- cific design criteria, and no reference to a logical office building code (if available): • Remote sensing imagery and rainfall inten- sity calculations associated with major Failure to comply with codes is a major cause storm events (from the National Oceanic of vulnerability in buildings. Often perverse and Atmospheric Administration, National incentives make it more attractive for admin- Hurricane Center, or similar agency) istrators, architects, builders, contractors and even homeowners to circumvent construc- • Consultant reports containing rainfall event tion standards (UN-Habitat 2009, 3). data (intensity, duration, and frequency) A consequence is that, in vulnerable commu- 9.5.3 Cracks in houses nities, residents do not always appreciate the Cracks in concrete structures can provide use- impact of poor construction on the movement ful clues to the stability of a slope. They are all of structures. 3 5 8    C H A P T E R 9.   P RO J E C T E VA L U AT I O N TAB L E 9.5  Landslides reported pre- and post-project with respect to major rainfall events in the Eastern Caribbean RAINFALL IMPACT Post-MoSSaiC 2006 2007 2008 2010 111 mm, 132 mm, 340 mm, 533 mm, NUMBER OF 1-in-4-year 1-in-5-year 1-in-100-year > 1-in-500-year COMMUNITY HOUSEHOLDS Pre-MoSSaiC 24-hour event 24-hour event 15-day event 24-hour event None reported; None reported; Major slides at reactivation of St. Lucia 1 55 landslide in None reported None reported low rainfall rates landslide in adjoining area adjoining area Major slide and Minor slide Minor slide evacuation of St. Lucia 2 None reported within within 100 homes in community community adjoining area 428 St. Lucia 3 Major slide None reported None reported None reported Modest slides St. Lucia 4 affecting None reported None reported None reported properties Retaining wall St. Lucia 5 20 failures and None reported None reported significant slides Major previous slide with several lost St. Lucia 6 60 None reported houses; subsequent minor landslides Landslide potentially St. Lucia 7 30 None reported threatening highway Landslides with St. Lucia 8 40 None reported two houses lost Landslide with St. Lucia 9 21 None reported one house lost Landslide and St. Lucia 10 20 collapsed None reported retaining wall Dominica 1 72 Major slides None reported None reported n.a. Note: n.a. = not applicable. Blank cells indicate that the project had not been implemented at the time of the rainfall event. Major rainfall events that triggered landslides in St. Lucia and/or Dominica were as follows:’: • 2006: September 2–3 • 2007: Hurricane Dean, August 16–18 • 2008: October 9–24 • 2010: Hurricane Tomas, October 30 (rainfall data for Castries, St. Lucia) Although structural cracks may be the first residents often inappropriately attribute indication of slope movement, there are a vari- these changing conditions to slope instabil- ety of reasons for cracks: ity. • Shallow foundations in deep residual soils • Too little cement in the mix, insufficient can move when soil water conditions change; reinforcement, poor design, and other ele- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 5 9 distinguish types of crack behavior and FI G U R E 9.6  Benchmarking major rainstorms with satellite imagery causes: • Static: not increasing in width, and hence not a cause for concern • Cyclic: the crack opens and then partially closes, following a cyclic pattern, likely due to shrinking and swelling of the soil caused by seasonal changes in soil water condi- tions on the slope • Progressive: a steady increase in width over time, which may suggest that there is ground movement (slope instability) and that the foundations are inadequate to pro- tect the structure (figure 9.7). 9.5.4 Surface and subsurface water MoSSaiC drainage interventions are designed to capture surface water and reduce infiltra- tion into slope materials in order to improve Source: Image courtesy of National Aeronautics and Space Administration. slope stability. The twofold effect on slope hydrological processes should be a reduction in both unmanaged surface water runoff and ments of poor construction can result in the moisture content of slope materials in inappropriate or uneven loading on a struc- landslide-prone locations. Changes in surface ture. water flows and saturated soils can be observed by residents, and subsurface water levels can • Most buildings experience cracking natu- be monitored with simple methods. rally at some point during their service life. Interpreting the causes of erosion and It is important to attempt to distinguish saturation between cracks in buildings caused by land movement, poor construction, or a combina- Residents are often concerned about surface tion of both. Building cracks are frequently a water flows or the emergence of groundwater cause of concern to residents, but are rarely around their house causing soil erosion and investigated in a systematic manner that fos- affecting house foundations (figure 9.8a). ters risk reduction or reassures residents. Although erosion is not a landslide process, it can indicate inadequate surface water man- Evidence base agement and lead to oversteepening at the Monitoring the changes in structural crack base of slopes. Saturated conditions can be width helps determine the cause of cracking caused by a shallow (near-surface) water table and the remedial work that should be speci- emerging locally at the soil surface as return fied. Because crack monitoring takes time, it is flow, and can potentially lead to soil erosion essential to begin at the earliest opportunity and undermining of foundations (figure 9.8b). and continue throughout the period of inspec- Evidence base tion and investigation. Cracks in structures can be monitored Use the slope process map (chapter 5) to iden- simply and inexpensively using crack moni- tify the locations of surface water flows and toring gauges (see section 9.5.3) in order to saturation prior to the project. Revisit these 3 6 0    C H A P T E R 9.   P RO J E C T E VA L U AT I O N FI G U R E 9.7  Assessing and monitoring F IGUR E 9. 8  Surface and subsurface water structural cracks undermining stability of house structures a. Cracks in structure attributable to poor construction (insufficient pile depth). a. Surface water. b. Subsurface water. cate postproject slope hydrology conditions on a plan of the implemented drainage works. Consider monitoring water tables close to properties in the following locations: • Where saturated soils occur • In areas prone to instability • Downslope of intercept drains. b and c. Worsening of cracks attributable to a progressive landslide which continued to move For example, figure 9.9 shows a 20 degree over a four-year period, finally resulted in a slope, upslope of which is a zone of significant complete loss of property. topographic convergence. Despite the shallow nature of the topography, the water table is close to the soil surface and is the cause of locations after project completion to deter- instability. Note the presence of dasheen, a mine if the slope hydrology has changed. Indi- potential indicator of near-surface saturated CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   3 61 F IG U R E 9.9  Convergence of water upslope F IGUR E 9.10  Drain performance results in slope instability and property destruction on shallow slope soil water conditions (see section 3.5.5). The water table depths in such an area could be monitored to ascertain whether, over time, an upslope drainage intervention has had a bene- ficial effect in lowering the water table. a. Discharge in a stepped drain during a major storm event indicates adequate capacity. Water tables can be monitored simply, effi- ciently, and inexpensively using low-tech piezometer systems (section 9.7.4). These sim- ple piezometers take the place of costly auto- mated monitoring and data-logging devices. Where community participation in the project has been high, residents may carry out moni- toring themselves after some basic instruction. 9.5.5 Drain performance Drain performance should be carefully moni- b. Resident notes maximum depth of observed tored after project completion. Government flow in a recently constructed drain during a engineers and community task teams should storm event. organize site visits during major storm events to check drain capacity (figure 9.10a). Addi- tionally, residents can be asked to indicate, 9.5.6 Environmental health benefits record, or recollect observed maximum flow depths in drains relating to the project (fig- In poorly drained areas with inadequate sani- ure 9.10b). tation, urban runoff mixes with excreta, The following comprises the evidence base spreading pathogens around communities and for drain performance: increasing health risks from various water- borne diseases (Parkinson 2003) (figure 9.11). • Depth of flow during and after heavy rain- These circumstances allow the transmission fall of a number of significant diseases, including • Rainfall data (intensity, volume, and dura- diarrheal diseases and malaria (table 9.6). tion) for extreme events Stagnant water also provides a breeding ground for the Aedes aegypti and Aedes albop- • Evidence of blockages or overflowing ictus mosquitoes that spread dengue fever. • Evidence of cracks and leaks Dengue fever is endemic to most tropical 3 62    C H A P T E R 9.   P RO J E C T E VA L U AT I O N countries, and cases have increased in many the potential negative health effects of insecti- regions in recent years. Similarly, there has cides. also been an increase in the number of cases of Residents in some communities with the more severe dengue hemorraghic fever in MoSSaiC interventions have noted that their Latin America and the Caribbean (figure 9.12). children’s health has improved due to less The primary method of controlling Aedes stagnant water and that the number of mos- aegypti is by eliminating breeding habitats quitoes has been reduced. By improving sur- (figure 9.13). This may be achieved by effective face water drainage and reducing stagnant drainage, emptying containers of water, or water, it is possible that MoSSaiC projects can adding insecticides or biological control agents reduce the number of suitable habitats for the to these areas. Reducing areas of stagnant mosquitoes that spread dengue fever. Evi- water is the preferred method of control, given dence of the effect of MoSSaiC on environ- FI G U R E 9.11  Stagnant water and disease transmission: The health consequences of poor drainage People urinate and Stagnant water provides defecate into water, Mosquito disease breeding place for owing to unavailability vectors breed in schistosomiasis snail host of latrines standing water Stagnant water Schistosomes penetrate contaminates skin of person standing in shallow water stagnant water Stagnant water contaminates aquifer water supply Source: Cairncross and Ouano 1991. TAB L E 9.6  Transmission routes of water-related diseases CLASSIFICATION TRANSMISSION ROUTE EXAMPLE OF DISEASE TRANSMITTED Waterborne Through ingestion of pathogens in • Diarrheal diseases drinking water • Enteric fevers, such as typhoid • Hepatitis A Water washed Through incidental ingestion of • Diarrheal diseases pathogens in the course of other • Trachoma activities; results from having insuffi- • Scabies cient water for bathing and hygiene Water based Through an aquatic invertebrate host; • Guinea worm results from repeated physical contact • Schistosomiasis with contaminated water Water-related Through an insect vector that breeds in • Malaria (parasite) and yellow fever (virus) insect vector or near water Source: Zwane and Kremer 2007. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   3 63 mental health issues is currently anecdotal, F IG U R E 9.1 2  Laboratory-confirmed dengue but could be investigated further. hemorraghic fever in the Americas prior to 1981 and 1981–2003 9.5.7 Economic appraisal: Project value for money Economic appraisal refers to various analytic methods that investigate whether projects and programs deliver value for money. The scope of an economic appraisal can range from cal- culation of simple measures of the economy, efficiency, and effectiveness of a project to analysis of the costs and benefits of that proj- Source: Centers for Disease Control and Prevention, ect over its lifetime. Ideally, an economic http://www.cdc.gov/Dengue/epidemiology/index. html. appraisal should be carried out both during the project planning phase and as part of the evaluation of the completed project. A particular challenge in assessing the F IG U R E 9.1 3  MoSSaiC and mosquito direct benefits of DRR lies in the fact that such breeding habitats benefits occur in the future as avoided costs rather than as a continual flow of positive ben- efits: the benefits are not tangible; they are…disas- ters that did not happen. So we should not be surprised that preventive policies receive support that is more often rhetorical than substantive (Annan 1999, 3). It is vital that economic appraisal of landslide a. MoSSaiC interventions can help control mosquito habitats by removing areas of risk reduction projects be carried out, not only stagnant water drainage. as a means of ensuring accountability, but in order to build the evidence base for ex ante landslide mitigation. Economic appraisal of MoSSaiC projects Economic appraisal of MoSSaiC projects must consider whether the project budget has been spent in the right way and on the right things— whether the project has been efficient and effective. For example, a particular MoSSaiC project may use resources very economically and efficiently and build a substantial network of well-constructed drains in a community. However, if the drains are in the wrong loca- tion or are unnecessary (not an appropriate solution to the landslide hazard), then the project will not have met its objective of reduc- b. A discarded old freezer is a perfect habitat for mosquito breeding. ing landslide risk and will not be cost-effective or physically effective. Another project may be 3 6 4    C H A P T E R 9.   P RO J E C T E VA L U AT I O N very effective in reducing the physical land- inputs, outputs, outcomes, and objectives, and slide hazard, but in an inefficient way by over- where these measures are the same for multi- spending on materials and other inputs. This ple projects. The value for money of each proj- would lead to the conclusion that the project ect is demonstrated in relation to comparable has been effective in meeting a key outcome, projects. This approach is not appropriate for but not in a cost-effective manner. assessing complex projects with multiple This subsection outlines two possible interrelated objectives, or for interproject approaches to the economic appraisal of com- comparisons where the performance metrics pleted MoSSaiC projects: are different for each project. • Simple measures of project value for money Cost-benefit analysis based on the monetary costs of producing Governments and donors might agree that the desired number of units of project out- mitigation is a good idea, but to answer the puts and/or outcomes in order to meet the question “will it pay?” requires evidence of the project objectives likely returns on investment made in the proj- • Cost-benefit analysis, which seeks to quan- ect. Cost-benefit analysis provides a frame- tify all of the costs and benefits of the proj- work for monetizing the present and future ect in monetary terms, including items for costs and benefits associated with different which the market does not provide a satis- projects—either at the project appraisal stage factory measure of economic value or as an ex post assessment. While the simple cost-efficiency and cost-effectiveness ques- Simple measures of project value for money tions described above consider projects in The MCU should use the generic questions on relation to each other, cost-benefit analysis project economy, efficiency, and effectiveness allows the absolute value of projects to be in table 9.7 to create a list of questions directly quantified. related to MoSSaiC project evaluation (mea- Cost-benefit analysis of specific DRR proj- sured in terms of inputs, expenditure, outputs, ects has consistently found that mitigation and outcomes). pays. In general, for every $1 invested, between This approach to appraising project value $2 and $4 are returned in terms of avoided or for money is straightforward to understand reduced disaster impacts (Mechler 2005; and use. It works well where there are a small Moench, Mechler, and Stapleton 2007). number of clearly defined and measurable Although such statements can make a con- TAB L E 9.7  Simple questions to help measure MoSSaiC project value for money MEASURE OF VALUE GENERIC QUESTION MoSSaiC PROJECT EVALUATION EXAMPLE Economy Have project resources been Has the method of procurement of materials used carefully to minimize (sand, cement, reinforcement, etc.) enabled expenditure, time, or effort? the selection of the cheapest supplier? (The cheapest supplier is not necessarily the best supplier.) Efficiency Has the project delivered the How many dollars (input) did it cost to required outputs for a minimum construct a meter of drain (output), and is this input of cost, time, or effort; or unit cost higher or lower than it should have obtained maximum benefit been (given environmental factors such as the from a given level of input? need to carry materials to the site)? Effectiveness Have the project outputs and Are the new drains and roof gutters capturing outcomes enabled project the anticipated proportion of rainwater and objectives to be met as fully as surface water runoff? Has slope stability been possible? improved? CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 6 5 vincing case for risk reduction, they should be of landslide hazard reduction, this requires treated with caution (Twigg 2004), as studies calculation of the probability of landslide are few and far between—at least in the pub- occurrence with and without intervention. lished literature—and are usually presented as These calculations can be made using a statements of fact without explaining how the physically based slope stability model to calculations were made. As Twigg (2004, 358) determine the rainfall return frequency notes, “The readiness with which publications required to trigger a landslide. on disasters repeat such assertions should per- 3. Discount all expected future landslide haps be worrying, as it suggests that little sub- costs into present values according to stantiated data is available.” how far into the future they are expected Because such studies are relatively scarce, to occur. The present value depends on the especially in developing countries and with discount rate and project lifetime specified respect to landslide risk reduction, investment (i.e., how long the project infrastructure in DRR remains low in the face of numerous will continue to provide a reduction in competing development opportunities (Ben- landslide hazard). son and Twigg 2004). Use the following steps as a guide in under- 4. Use cost-benefit analysis decision crite- taking a cost-benefit analysis of a MoSSaiC ria to determine project value for money. project. Standard criteria include the benefit-cost ratio, the net expected present value of the 1. Monetize the costs and benefits of the project, and the internal rate of return. project. If these are given in physical or The benefit-cost ratio of a landslide risk welfare terms, different methods can be reduction project is the ratio of the cost of used to convert them to monetary values. the initial investment in hazard reduction For DRR projects, the main physical bene- to the difference in the net expected value fits are the avoided future disaster costs of landslide costs before and after the proj- (rebuilding, relocating, and replacing pos- ect (the benefit in terms of avoided costs). sessions). Thus, the cost of landslides with The net expected present value is simply and without the project, and the difference the project benefits minus the costs. It is between the two scenarios, should be cal- positive where the project results in a culated. To determine these costs, the reduction in future landslide costs (and nature of the anticipated landslide hazard potential additional benefits to the com- (type and magnitude) needs to be known at munity) that outweigh the cost of the a spatial scale relating to the landslide haz- intervention. Conversely, the net expected ard reduction project. This allows identifi- present value could be negative if the proj- cation of elements exposed to the hazard ect has the effect of increasing the land- (such as houses) and estimation of the likely slide hazard or if a landslide destroys part damage caused (the landslide cost). There of the project. may also be less tangible environmental, welfare, and social benefits to the commu- An example of a MoSSaiC project cost- nity. In some analyses, a value of life benefit analysis is given in section 9.7.5. A assumption is made to account for potential helpful review of general cost-benefit analysis loss of life; assigning such values can be tools and resources can be found at the controversial, and they are generally uti- ProVention Consortium website (http://www. lized in wide-area studies where multiple preventionweb.net/files/8088_WP1highres1. hazards and risk reduction projects are pdf ). being compared. The results of cost-benefit analysis should 2. Estimate the probability of landslide be used in the context of other project infor- costs occurring in the future. In the case mation when evaluating the project as a whole: 3 6 6    C H A P T E R 9.   P RO J E C T E VA L U AT I O N The question often left for us to ponder when nity-organized events to clear the drainage reviewing Cost-benefit Analysis (CBA) on a network and debris traps particular hazard mitigation project is not what values we place on the moneterized • Fewer cut slopes excavated at the rear of impacts but rather how large or small are properties these compared to the “value” of the non- monetized impacts. CBA alone cannot • An increased general awareness among the answer this question, but human experience majority of residents of the need for good and reflection can (Ganderton 2005). drainage practices, such as the prompt reporting of leaking water supply pipes to 9.5.8 Adoption of good landslide risk the water company reduction practices Government evidence One of the key objectives of MoSSaiC is to At the government level, decision makers encourage individuals, communities, and gov- should seek to embed the above practices into ernments to adopt practices that reduce urban larger-scale infrastructure and community landslide hazards. Chapter 8 outlined the pro- development projects. Evidence of adoption cess of behavioral change in terms of a ladder can include the following: of adoption (from perception and awareness, • Using appropriate scientific methods for to knowledge and action, and finally to adop- assessing slope stability prior to construc- tion of MoSSaiC), factors affecting motiva- tion on landslide-prone slopes tions and intentions to act, and strategies for communicating and capacity building. The • Including the provision of adequate drain- resulting behavioral change strategy was sum- age in road and footpath construction proj- marized in the form of an outcome map (sec- ects on slopes tion 8.7.2). • Including specific contractual require- Use this outcome map to evaluate whether ments for drain cleaning and maintenance the planned outputs (communication, capac- when new infrastructure is constructed ity-building activities) have been delivered. To evaluate the effectiveness of the behavioral • Incorporating slope stability assessment change strategy, look for evidence of adoption and drainage standards into planning pro- of good landslide risk reduction practices (dis- tocols and other policy instruments cussed in this section) and policies (sec- • Generating awareness and providing train- tion 9.5.9) during and after the project. ing for government practitioners involved Community evidence in activities that may affect slope stability. Evidence of communities adopting good land- slide risk reduction practices might typically 9.5.9 Development of new landslide risk involve the following: reduction policies Evidence-based policy making is becoming • Installation of drains around houses using more central to development funding and poli- the residents’ own resources cies. Policy makers are increasingly asked “to • Installation of roof guttering and adoption explain not just what policy options they pro- of roof water harvesting by residents pose, and why they consider them appropri- ate, but also their understanding of their likely • Reduction in the dumping of garbage in effectiveness” (Segone 2008, 28). This drains approach requires a move from opinions • Maintenance and cleaning of drains around (which rely on ideals, speculation, or the selec- homes and, more widely, during commu- tive use of evidence) to evidence from project CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 6 7 evaluations, academic research, and experi- interventions having actually worked (World ence (figure 9.14). Bank 2003, 212). The cycle of interactions among govern- F IG U R E 9.1 4  Dynamics of policy making ment, communities, and international agen- cies can be used as a platform for behavioral technical capacity evidence change, as shown in figure 9.15, which depicts based six steps from the formation of the MCU evidence influenced (step  1) through the recognition of on-the- opinion ground projects by agencies (step 4) and the based move to a wider acceptance of preventative policies and implementation (step 6). This political process cycle is reflected in the project sequence and Source: Segone 2008. structure of this book: starting with establish- ing government teams (chapter 2), moving to understanding and implementing landslide The move from opinion to evidence, and hazard reduction measures through commu- the adoption of new evidence-based policies, nity participation (chapters 3–8), and ending tends to be both strategic and incremental. with the development of the evidence base The evidence base is developed through a through project evaluation (chapter 9). cycle of pilot projects, project evaluation, rec- The MCU, project decision makers, and ognition of project performance and value by funders should use this subsection to identify policy makers and funders, increased policy how MoSSaiC can provide an evidence base commitment to the initiative, and the resourc- for ex ante landslide risk reduction and to ing of similar initiatives. This strategic incre- evaluate how effective the project has been in mental approach can create favorable condi- influencing policy. tions for reform over the longer run, thus The MCU should present MoSSaiC project enabling behavioral change in the institutional progress, outputs, and outcomes to policy and policy environment (Lavergne 2004, 2005; makers in a way that answers their questions World Bank 2004). In contrast, incremental and enables them to make evidence-based but nonstrategic temporary work-arounds decisions. Specific actions that can help sup- cannot create conditions for policy change. port evidence-based policy are listed in The objective has to be that of striking a sen- table 9.8. sible trade-off between comprehensive and Evaluating MoSSaiC influence on policy incremental reforms—seeking early wins for stakeholders and supporting policy champi- Evidence that could be recorded as policy ons and cross-agency teams that can bring uptake might include the following: along others of like mind (World Bank 2004). • Inclusion of MoSSaiC in government disas- MoSSaiC projects and evidence-based policy ter risk management planning documents MoSSaiC projects provide policy makers with (e.g., Government of St. Lucia 2006, 26–27) both the scientific basis for landslide hazard and promotion in regional disaster risk reduction in communities and the evidence of management forums effective solutions delivered on the ground: • Community-to-community knowledge To change the perceptions of individuals, as transfer (figure 9.15, step 3) well of those of Governments regarding the most cost-effective way of reducing risk, is • Interest, visits, and support from new best achieved when there is clear evidence of donors (step 4) 3 6 8    C H A P T E R 9.   P RO J E C T E VA L U AT I O N FI G U R E 9.15  Process of strategic incrementalism Gov ern 1 Formation of the MCU 2 me Government/social intervention fund/ nt community project 1 3 Community-to-community knowledge transfer es 4 International development agencies 2 nci engage with community evidence base ge 5 la 5 All stakeholders involved in proposals Internationa 6 Evidence base for agencies to shift to 6 3 preventative policies and funding 4 6–1 Policies and funding y nit Commu 2–5 MoSSaiC community focus Source: Anderson at al. 2010, based on Segone 2008. TAB L E 9.8  Requirements for achieving evidence-based policy in ex ante disaster risk reduction CATEGORY GENERIC REQUIREMENT MoSSaiC REQUIREMENT Require the publication of the evidence Provide project outputs from community base for policy decisions selection, mapping, hazard assessment, and drainage design (chapters 4–6) Evidence- Require departmental spending bids to Provide supporting evidence from previous based provide a supporting evidence base MoSSaiC interventions, including evidence policy of value for money and results of cost- require- benefit analysis (chapter 9) ments Provide open access to information leading Communicate project information through to more informed citizens and interest community participation and mass media, groups and encourage empowerment of stake- holders (chapters 5 and 8) Encourage better collaboration across Encourage collaboration of the MCU and internal services government task team members (chapter 2) Facilitating Cast external researchers more as partners Encourage inclusion of academics and better than as contractors researchers in the MCU or government task evidence teams (chapter 2) use Integrate analytical staff at all stages of the Provide opportunities for the MCU and policy development process government task teams to present the project to decision makers (chapter 2) Source: Nutley, Davies, and Walter 2002. • An enlarged group of stakeholders (govern- 9.5.10 Finalizing the project evaluation ment, donors, social funds) working process together and submitting a new proposal for MoSSaiC interventions (step 5) The MCU should decide with government decision makers and funders who will be • Evidence of donors themselves promoting responsible for project evaluation both during and proposing MoSSaiC interventions and after the project. The responsibility for (step 6). medium- and long-term postproject evalua- CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   3 69 tion (or monitoring) may need to reside with a DRR can deal with current climate variability local agency that already has a mandate, or and be the first line defence against climate change, being therefore an essential part of research program, for disaster risk assessment adaptation. Conversely, for DRR to be suc- and management. cessful, account needs to be taken of the shifting risks associated with climate change, MILESTONE 9: and ensure that measures do not increase vulnerability to climate change in the Evaluation framework agreed medium to long-term (Mitchell and van Aalst upon and implemented 2008, 1). “Climate proofing” is shorthand for the identification and reduction of risks posed to 9.6 ADDRESSING LANDSLIDE development projects by climate variability RISK DRIVERS OVER THE and change. Today the need for climate proof- LONGER TERM ing is greater than ever as risk drivers change (see section 9.6.3) and increase the hazard, The drivers of landslide risk relate to the hazard exposure, and vulnerability of communities (the landslide event) and the vulnerability of and regions to climate-related disasters. exposed elements (such as people, communi- Climate proofing in the most vulnerable ties, and infrastructure) to damage by that haz- communities requires urgent attention ard event. Since the primary aim of MoSSaiC is because the destruction of, or damage to, to identify and reduce physical landslide hazard unauthorized housing is one of the most com- drivers affecting the most vulnerable urban mon and serious impacts of many extreme- communities, the evaluation process (sections weather events (Parry et al. 2009). Unauthor- 9.3–9.5) is concerned with project effectiveness ized housing is often not constructed to in reducing landslide hazard and improving withstand such events even under current cli- slope management practices over short- and matic conditions: medium-scale time frames. …property is built at a substandard level and This section considers MoSSaiC as a poten- does not conform even to minimal building tial contributor to holistic policy responses to codes and standards. This widespread failure landslide risk and trends in landslide risk driv- to build enough weather resistance into ers (both physical and societal) over longer existing and expanding human settlements is time scales: the main reason for the existence of an adap- tation deficit… The evidence suggests • DRR under present and future climate sce- strongly that the adaptation deficit continues narios to increase because losses from extreme events continue to increase. In other words, • Risk transfer through insurance at individ- societies are becoming less well adapted to ual and national scales current climate. Such a process of develop- ment has been called “maladaptation” • “No regrets” landslide risk management (UNFCCC 2007, 99). given uncertain trends in risk drivers. MoSSaiC can contribute to a planned har- 9.6.1 Disaster risk reduction and climate monization and alignment of incentives of cli- proofing mate change adaptation in developing coun- DRR and climate change adaptation policies tries. Table 9.9 sets out key elements of are, to some extent, complementary even MoSSaiC that can be regarded as contributing though they have been evolving independently to climate proofing in vulnerable communi- until recently: ties. 370    C H A P T E R 9.   P RO J E C T E VA L U AT I O N TAB L E 9.9  Summary of MoSSaiC elements contributing to climate proofing ELEMENT OF MoSSaiC METHODOLOGY THAT CURRENT ISSUE RELATING TO LANDSLIDES IN COULD CONTRIBUTE TO WIDER CLIMATE- VULNERABLE COMMUNITIES PROOFING AGENDA Rainfall-triggered landslide hazard Frequent landslides triggered by low-intensity or Rainfall-triggered landslide hazard reduced through low-duration rainfalls; potential for major landslide surface water management in vulnerable commu- events with high-intensity/-duration, low-frequen- nities cy rainfall events Surface water management issues on slopes Absence of roof water capture and surface water Household roof and gray water capture and drainage leading to rapid rainfall runoff, surface surface water management, reducing landslide haz- water infiltration, saturated soils, and localized ard and potentially improving environmental flooding health issues by reducing stagnant water Water supply issues Piped water supply issues, but limited capture of Integrated rainwater harvesting and storage for use rainwater by households provides reliable supply for washing/cleaning when piped water is unavailable Damage to houses by extreme rainfall events (e.g., hurricanes) Roof and house structures vulnerable to damage Retrofitting of hurricane straps increases the by strong winds likelihood of roofs staying intact in storm events, ensuring continued rainwater capture Public awareness of landslide hazard causes and solutions Need for awareness of good slope management Community engagement throughout the MoSSaiC practices and how to reduce landslide hazards at project helps deliver better understanding of the community scale landslide risk and good slope management and construction practices Landslide risk reduction policy Lack of policy regarding landslide risk reduction in MoSSaiC methodology discussed by international vulnerable communities agencies in the context of contributing to climate proofing (World Bank 2010a) encourages govern- ments to consider community-based policies and approaches to landslide risk reduction 9.6.2 Connecting hazard reduction and Despite recognition of the importance of insurance risk prevention, there is still comparatively little practical implementation of risk reduc- The aim of a holistic landslide risk reduction tion measures on the ground in developing strategy should be to reduce the degree to countries (Wamsler 2006). Successful which vulnerable communities and govern- MoSSaiC projects thus represent a significant ments have to bear, or cope with, the impact of opportunity to reduce overall landslide risk landslides; since “what cannot be prevented or and the risk burden on communities and gov- insured, has to be borne” (World Bank 2010b, ernments. 154). Landslide hazard, exposure and vulnera- This section considers how hazard reduc- bility reduction, and risk transfer strategies tion initiatives such as MoSSaiC might be con- can each contribute to a reduction in the level nected to risk insurance for households in vul- of risk carried by communities and govern- nerable communities, and how ex ante ments. Some of these preventative, insurance, government investment in risk reduction and coping mechanisms are highlighted in might reduce the resource gap for ex post table 9.10. disaster risk financing (figure 9.16). CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   37 1 TAB L E 9.10  Holistic context of prevention, insurance, and coping strategies of individuals, communities, and governments RISK REDUCTION MEASURE INDIVIDUAL/HOUSEHOLD COMMUNITY GOVERNMENT Prevention Investment to protect assets Community training programs Public works in support of and participation in risk mitigation measures mitigation construction Self-insurance Owning financial and Local borrowing Adequate physical and social nonfinancial assets infrastructure Market insurance Property and catastrophe Microfinance Sovereign budget insurance insurance and catastrophe bonds Coping Running down stocks of Interhousehold transfers and Disaster aid funds, social human and physical resources private remittances investment projects by social funds, and other cash-based safety nets Source: World Bank 2010b. Note: MoSSaiC is focused on preventative measures (highlighted). F IG U R E 9.1 6  Generalized impact of MoSSaiC interventions on reducing the burden of coping remaining landslide risk after hazard reduction …after exposure and/or vulnerability reduction …after risk transfer (self and market insurance) without MoSSaiC intervention with MoSSaiC intervention …remaining risk (coping) (hazard reduction) total landslide risk: f(hazard, exposure, vulnerability) Challenges of insuring households in vulnerable whose costs are up front and payoffs far communities off. • The most vulnerable require direct and Household risk from disasters, including land- immediate assistance after a disaster— slides, can theoretically be transferred through schemes that pool losses will not suffice. the insurance market. However, increasing the disaster resilience of vulnerable households Table 9.11 summarizes these constraints through schemes that aim to spread risks faces from the standpoints of government, insurers, major constraints: and households. Insurance solutions can only support effec- • The most socioeconomically vulnerable tive adaptation where they are implemented households have income profiles that are alongside measures to reduce disaster risk and far below minimum acceptable thresholds increase societal resilience. If not embedded in and virtually no capacity to save. a comprehensive risk reduction strategy, • The budgets of these most vulnerable insurance may actually encourage risk-taking households clearly have many demands behavior, potentially leading to greater fatali- that are more pressing than insurance, ties and damage. 37 2    C H A P T E R 9.   P RO J E C T E VA L U AT I O N TAB L E 9.11  Design issues and challenges for linking risk reduction and insurance CHALLENGE GOVERNMENT INSURANCE HOUSEHOLD Generic (apply • Commit to cover upfront • Commit to engage in dialogue • Upfront costs/affordability to all) program development costs about risk reduction • Perception of risk • Manage perception of risk and • Design innovative longer-term • Perception of benefit (particu- benefits (long term) versus costs insurance tools applicable in larly given time scales of benefit) • Coordinate with postdisaster developing country context • Availability of postdisaster assistance to avoid disincentives • Design tools to address moral assistance • Build institutional capacity hazard Awareness • Develop appropriate dissemina- • Develop appropriate dissemina- • Engage in insurance literacy raising and risk tion channels for risk information tion channels for risk information programs information • Need tools to build ability to understand risk information Risk pricing (i.e., • Address equity issues to ensure • Need high-resolution risk analysis • Upfront costs of risk reduction a price signal to affordability of and access to • Lower transaction costs (expense versus relatively small potential incentivize risk insurance for vulnerable/poorer and time for verification of risk premium adjustment reduction) communities in high-risk areas and loss in developing countries) Enabling • Governance • Potential limits to competitive- • Understanding of DRR and conditions and • Legal frameworks ness and implications for insurance regulation actuarial soundness of insurance • Availability of technical assistance • Monitoring and enforcement programs (adaptation support) Financing risk • Establish funds or invest in ex • Upfront costs • Potential of risk reduction for reduction ante risk reduction measures that • Need close collaboration with insurance coverage (exchange of are independent of election public sector to coordinate risk work time devoted to risk cycles or other political reduction compatible with reduction measures for insurance considerations (to overcome insurance programs, risk coverage) barriers, i.e., no reward for information catastrophe avoided) • “Who pays versus who benefits”; insurer may see little direct benefit from investment Risk reduction • Voluntary participation in • Competitive market conditions • Need knowledge of appropriate as a prerequisite insurance programs with may work against incentives if risk reduction techniques and for insurance prerequisite of ongoing DRR not coordinated with public options sector Source: Adapted from UNFCCC 2009. Linking climate proofing and household Development Foundation in St. Lucia offered a insurance hurricane-resistant home improvement pro- gram for low-income earners. The program A major challenge for disaster-prone low- trained local builders in safer construction, income countries is to develop instruments offered small loans to families wishing to with adequate incentives (inevitably entailing upgrade their homes, and provided the ser- subsidies) that will make it possible for the vices of a trained building inspector who poor to participate in disaster risk mitigation approved materials to be purchased and veri- programs such as climate proofing and insur- fied that minimum standards were met. Low- ance. income homeowners who strengthened their It is worth noting the experience of an homes through the program could obtain insurance program that ran in St. Lucia for six property insurance underwritten by a regional years (OAS 2003). The National Research and subsidiary of a U.K.–based insurance company CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   373 and established through a local broker. The Landslide risk reduction and macrofinancing insurance plan covered major natural disas- disasters ters. Figure 9.17 shows the management struc- ture of the loan process and associated insur- Insurance is just one of several financial ance scheme. instruments used by governments to fund The insurance scheme was mandatory for disaster relief and recovery. Table 9.12 lists a recipients of the home improvement loans. variety of other ex ante and postdisaster Full coverage with a 2 percent deductible was financing instruments available to govern- specified in the policies. Premium rates ranged ments. Disaster financing is especially from 0.60 percent for concrete block homes to demanding for developing countries because 1.05 percent for homes made of timber. there can be a shortfall, known as a resource Between 1996 and November 2002, 345 loans gap, between the disaster costs and the funds were disbursed within this program, with an available to the government to rebuild and average loan size of approximately $4,100 (in provide relief and assistance with the recovery 2002 dollars) (OAS 2003). efforts (Mechler et al. 2010). These resource The program is noteworthy because it is a gaps are often greatest immediately after a rare example of targeting insurance to the disaster when funding needs are urgent and most vulnerable households, coupling home high, but funds and financial assistance have improvement for natural hazard mitigation not yet been mobilized (Ghesquiere and Mahul with property insurance cover. The home 2007). improvement conditionality of the scheme off- A country’s resource gap is calculated by set the reported “catch-22” insurance position identifying the probability (or annual recur- for natural hazard cover alone—namely, that rence interval) of a disaster event in which net natural hazard insurance premiums are usu- losses exceed all available financial resources ally very high, as only those likely to make fre- (figure 9.18). For some developing countries, a quent claims consider insuring themselves resource gap can be created by a disaster event against them. High premiums associated with with as high a probability of occurrence as 1 in hazard cover alone lead to one of two possi- 15 years (Mechler et al. 2010). bilities: the customer decides that the insur- The frequency and impact of disaster events ance is too expensive and does not insure the determine whether it is more effective for gov- property, or the insurance companies decide ernments to invest in risk reduction or risk there will be no profit in underwriting hurri- financing. Generally, risk prevention is more cane damage at a premium customers are will- cost-effective for high-probability events with low to medium-size losses, while risk financ- ing to pay and decline to offer the business. ing targets less frequent, higher-impact events Being mindful of the possible constraints (Mechler et al. 2010). For countries prone to mentioned above, funders and governments rainfall-triggered landslides and where high- could consider combining an insurance frequency events can trigger a resource gap, it scheme with MoSSaiC projects to create a is conceivable that a national program on comprehensive landslide risk management MoSSaiC projects could contribute to disaster plan in which resilience at a national scale. • preventative measures are provided (or encouraged) through MoSSaiC projects; 9.6.3 Anticipating future disaster risk scenarios • insurance is available for participating In chapter 1, a number of policy issues and households, assuming a model analogous to trends were identified that affect urban land- that outlined in figure 9.17; and slide risk in developing countries, including • should a landslide occur, the government the speed of conventional DRR uptake, the would manage a damage repair program. rate of societal change and urbanization, and 374    C H A P T E R 9.   P RO J E C T E VA L U AT I O N FI G U R E 9.17  Model used in St. Lucia for hurricane-resistant home improvement program for low-income earners Initial contact (receptionist) First interview Interview and loan application (loans/building officers) Site visit Environmental guidelines (loans/building officers) Siting criteria Construction details Minimum building standards Select builder and prepare drawings Design standards (building officer) Review file and environmental guidelines (unit head) Minimum building standards Standards met Loan approval (unit head, executive director, loan committee or board, depending on size of loan) Loan disbursement Construction phase Disbursements Site visits (accountant) (building officer) Minimum building standards Certification of completion and environmental guidelines (building officer) Standards met Loan completion Insurance coverage (accountant) Loan payment (accountant/loan officer) Closure of loan (accountant) Source: OAS 2003; reproduced with permission of the OAS General Secretariat. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   375 TA BLE 9.1 2  Sources of postdisaster financing PHASE Relief Recovery Reconstruction (1–3 months) (3–9 months) (+9 months) Donor assistance (relief) Postdisaster financing Budget reallocation Domestic credit External credit Donor assistance (reconstruction) Tax increase Budget contingencies Ex ante financing Reserve fund Contingent debt facility Parametric insurance CAT bonds Traditional insurance Source: Ghesquiere and Mahul 2007. F IG U R E 9.1 8  Hypothetical calculation base for the resource gap a. Loss function: Financing needs 0.10 10-year event 0.08 probability 0.06 0.04 0.02 100-year event 200-year event 0 0 2,000 4,000 6,000 8,000 10,000 12,000 losses in local currency units b. Financing sources: Financing supply 12 international bonds 10 borrowing from IFIs marginal cost 8 resource 6 domestic bonds gap and credit 4 diversion 2 grants 0 amount available Source: Mechler et al. 2010. Note: IFI = international finance institution. The resource gap is the shortfall between the cost of a disaster and the funds available to the government to rebuild and provide relief and assistance with the recovery efforts. 376    C H A P T E R 9.   P RO J E C T E VA L U AT I O N possible trends in other human or physical landslide risk drivers. A society may be chang- F IGUR E 9.19  Media recognition of the world’s urban population crossing the ing more quickly than DRR policies can be 50 percent mark adopted—e.g., in terms of rapid urbanization and a consequent growth in slum populations, leading to the development of communities on landslide-prone slopes, all of which are pow- erful drivers in a cycle of risk accumulation. Because property on landslide-prone slopes is cheaper to rent, the most vulnerable live in these areas. Further, because unauthorized houses can be built in a matter of days, people can move to urban areas faster than planning authorities can respond. DRR policies need to take different risk sce- narios into account. Scenarios are “plausible descriptions of possible future states of the world…not a forecast; rather each scenario is one alternative image of how the future can unfold” (IPCC 2011). Identifying future disaster risk scenarios involves thinking about and cre- Source: The Economist May 5, 2007. atively exploring what is happening now (trends that make headlines—figure  9.19) and projecting what the future holds (Rayner and • Maximum increase in landslide risk driv- Malone 1997). However, “in creating scenarios, ers. This scenario entails an increased researchers often extrapolate from the present number of high-intensity landslide-trigger- to posit a future that is ‘more of the same’” ing rainfall events driven by climate change, (Rayner and Malone 1997, 332). The future more high-density vulnerable housing cre- world of many current DRR approaches is ated by urban population growth, and essentially today’s world but more so: more mainstreaming, more knowledge transfer, more technology (largely of the same sort), more F IGUR E 9. 2 0  Conceptual diagram of a scenario funnel integration of multihazard mapping. History suggests that such an approach might be unre- alternative alistic. Mahmoud et al. (2009, 800) note that futures the simplest baseline future is that of an “offi- cial future,” a “business as usual” scenario of a widely accepted future state of the world. Most decision makers will not accept future alternatives unless the official future is ques- tioned. With respect to urban landslide risk, it is possible to define a set of different but plausi- ble alternative future scenarios (figure 9.20) relating to possible trends in human and phys- ical landslide risk drivers. The following two today time future horizon scenarios—which are physically, socially, and politically plausible—illustrate possible oppo- Source: Mahmoud et al. 2009. site extremes of a set of scenarios: CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   37 7 absence of planning and construction regu- resilience (limiting the currently observed lation and enforcement (all of which could landslide risk accumulation). be expected to further increase the cur- rently observed landslide risk accumula- Between these two extremes, various sce- tion). narios for landslide risk drivers could be envis- aged, modeled, and analyzed to identify differ- • Minimal increase, or even a decrease, in ent strategies to address future risk. MoSSaiC landslide risk drivers. This scenario contributes to those strategies by addressing assumes no change (or a reduction) in the current landslide hazard drivers and offsetting number of high-intensity landslide-trigger- potential future increases in those drivers, and ing rainfall events, housing density limits provides governments and communities with enforced on landslide-prone slopes, and the science, community, and evidence bases implementation of physical and socio- for effective landslide risk reduction over the economic measures to improve household long term. 378    C H A P T E R 9.   P RO J E C T E VA L U AT I O N 9.7 RESOURCES 9.7.1 Who does what CHAPTER TEAM RESPONSIBILITY ACTIONS AND HELPFUL HINTS SECTION Funders and Awareness of the importance of • Familiarity with the need to have measures of both 9.2.1 policy makers project evaluation project outputs and project outcomes Establish project KPIs • Agree on KPIs for both project outputs and outcomes 9.4 Helpful hint: Talk to other agencies and government 9.2.4 departments to see if project evaluation is already being Agree upon an agency to review carried out. There could be an opportunity to collaborate, project outcomes or for an existing arrangement to incorporate MoSSaiC evaluation needs. MCU • Discuss feasible arrangements with relevant agencies to 9.5 Develop project outcome ensure a project outcome schedule can be created and a schedule body made responsible for a medium-term evaluation Helpful hint: A specialist group (perhaps a college research 9.5.7 Arrange for a cost-benefit group, or an appropriate branch of government) may be analysis to be undertaken willing to undertake this task. • Observe changes in slope stability 9.5.1; 9.5.2 Develop database system for recording project outcomes • Acquire rainfall information associated with major storms Government task to show stability (or otherwise) of interventions teams Coordinate with community task teams • Provide commentary on drain performance during rainfall 9.3.2 Community residents contribute • Monitor cracks in structures and water table levels Community task to project evaluation teams • Describe conditions before and after the intervention Coordinate with government task teams 9.7.2 Chapter checklist SIGN- CHAPTER CHECK THAT: TEAM PERSON OFF SECTION 99KPIs for short-term project outputs identified and agreed upon 9.4 99KPIs for medium-term project outcomes identified and agreed upon 9.5 99Data collection roles and responsibilities agreed upon for all KPIs 9.4; 9.5 99Milestone 9: Evaluation framework agreed upon and implemented 9.5.10 99Policy for addressing landslide risk drivers over the longer term reviewed 9.6 99All necessary safeguards complied with 1.5.3; 2.3.2 9.7.3 Installing crack monitors sign of a serious defect affecting the building’s serviceability or structural stability. Monitor- Most masonry and concrete buildings crack at ing changes in crack width over time will estab- some time during their service life. The appear- lish if the crack is static, progressively opening, ance of a crack is a symptom of distress within or opening and closing following a cyclic pat- the fabric of the building. Often the cracking is tern of movement. This information is essen- of little consequence, but it could be the first tial in diagnosing the cause of the crack. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N   379 Simple gauges (figure 9.21a) allow monitor- ing of horizontal and vertical movement across F IGUR E 9. 2 1  Crack monitoring gauge and crack record charts a crack on a flat surface using two partially overlapping plates. The bottom plate is cali- brated in millimeters; the top plate is transpar- ent and marked with a hairline cross-shaped cursor. The gauge is preset at zero with four pegs. The pegs are removed after the gauge is fixed across the crack. As the crack opens, or if vertical movement occurs, the cursor moves relative to the calibration scale. Ideally, the gauge should be fixed with a. Callipers are used with the crack monitoring screws or rawl plugs and adhesive, as there is gauge to increase measurement resolution. the risk of tampering if screws alone are used. On some surfaces, only adhesive can be used; the adhesive must fully cure before the four plugs are removed. Once the gauge is set in place, the crack’s opening or closing can be monitored, and results recorded on a crack record sheet (fig- ure 9.21b). 9.7.4 Installing and using simple piezometers A simple piezometer can be used to measure the depth of the free water table below the b. Crack record charts. ground surface. The device consists of a tube Source: Avongard, www.avongard.co.uk. with holes in it, placed in a narrow borehole. Water enters the piezometer until it reaches the same level as that in the soil. To install a piezometer, perform the follow- Installing piezometers in an array may ing steps: allow determination of a groundwater surface (figure 9.22c). 1. Drill a hole in the soil 1–3 m deep, using a To read the piezometer, perform the fol- power soil auger (figure 9.22a). A hand-held lowing: power auger may be sufficient to insert a • Lower a piece of tubing into the piezometer piezometer to a depth of 1–2 m in residual and blow into it until bubbling is heard; this soils. In heavy clay soils, a more powerful indicates the water level in the piezometer. auger may be required. • Record the length of tubing used (remem- 2. Put a plastic piezometer tube in the bore ber to subtract the above-ground distance); hole; 2 inch plastic tubing can be used for this is the depth of the water table. the piezometer. Drill holes, typically toward the lower third of the tube at 10 cm Take and record regular readings from the spacing, to allow water to flow into the piezometer over a period of months, particu- tube. The holes can be drilled on site (fig- larly over the wet season. The readings can be ure 9.22b). used to ascertain any apparent reduction in 3. Cover the top of the piezometer to prevent water levels that could be attributed to surface rain from infiltrating. drainage works undertaken upslope. 3 8 0    C H A P T E R 9.   P RO J E C T E VA L U AT I O N 9.7.5 Cost-benefit analysis FI G U R E 9.2 2  Installing piezometers The components of the integrated model of landslide risk assessment, risk reduction, and cost-benefit analysis used in a MoSSaiC inter- vention are shown in figure 9.23. This cost- benefit analysis approach is illustrated using the example of Holcombe et al. (2011), the slope stability analysis for which can be found in section 5.6.3. Landslide hazard and drainage scenarios Two landslide scenarios were tested using CHASM (Combined Hydrology and Slope Sta- bility Model) (see figures 5.25 and 5.26): • Failure of the entire slope (cross-section X1-X2) a. Drilling for a piezometer installation. • Failure of multiple small cut slopes (cross- section Y1-Y2) (Holcombe et al. 2011). Prior to the construction of new drains, a rainfall event with a probability of 1 in 10 years was predicted to cause landslides along section X1-X2 which would affect a large part of the slope (figure 5.27), while a 1-in-5-year event was predicted to trigger smaller slides in multiple cut slopes along section Y1-Y2. b. Drilling holes in piezometer tube. After constructing new drains and captur- ing household water, less water was available for infiltration into the slope. Thirty-five per- cent of rainfall was known to be intercepted by roofs and conveyed to new drains, while approximately 50 percent of the remaining rainfall was estimated to be removed from the slope in the form of surface water runoff inter- cepted by drains. This was reflected in the slope stability simulations by reducing the water added to the slope, and an improvement in slope stability was demonstrated (fig- ure 5.28). The predicted probability of the two landslide scenarios was reduced to 1 in 100 years for the entire slope (cross-section X1-X2) and 1 in 50 years for smaller failures in cut slopes (cross-section Y1-Y2). c. Setting out piezometer array. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 8 1 FI G U R E 9.23  Components of an integrated model of landslide hazard and risk assessment TRIGGERING MECHANISM DATA a rainfall: intensity, duration, frequency HAZARD ASSESSMENT CHASM: Physically based Combined SLOPE DATA Hydrology and Slope Stability Model slope geometry and surface drainage: angles, heights, lengths, convergence soils and geology: HAZARD PARAMETERS strata, depth, strength, and hydraulic probability, location, parameters runout depth and distance surface cover and loading: vegetation, structural loading, point DATA ON ELEMENTS AT RISK DAMAGE ASSESSMENT water sources houses: Identification of exposed elements construction material, location and estimation of vulnerability INTERVENTION SCENARIO EXPOSURE & VULNERABILITY surface water drainage network, PARAMETERS roof guttering connections DIRECT PROJECT COSTS & BENEFITS n elements affected, damage (0–1) direct project costs cost of materials GOVERNMENT DATA cost of labor LANDSLIDE RISK: per scenario Project contract data, costs and direct landslide costs p(hazard), elements exposed, funding policies for postdisaster ( = benefits when landslide avoided) degree of damage rehabilitation, discount rate cost of temporary accommodation cost of rebuilding cost of replacing possessions COST-BENEFIT ANALYSIS: per scenario HOUSEHOLD SURVEY: direct and indirect benefits, revealed and stated net present value of costs, preference approaches for community INDIRECT PROJECT BENEFITS benefit-cost ratio willingness to pay for risk reduction or tangible benefits (monetized): accept risk (WTP/WTA) work missed water bills intangible benefits (not monetized): input data travel time to work intermediate time repairing house from damage outputs and inputs mosquitoes models, methods, improved environment and results b Source: Holcombe et al. 2011. Note: (a) Landslide risk assessment and cost-benefit analysis of risk reduction, (b) monetization of project costs and benefits. Monetizing project costs and benefits to the debris, and savings in water bills through har- community vesting of rainfall from roofs. The value of The expected damage to houses of different indirect benefits was assessed using stated and construction types was calculated from pre- revealed preference methods (via a household dicted magnitude and location of landslides. questionnaire) to determine willingness to pay The direct benefits of the landslide mitigation for benefits and willingness to accept compen- project were calculated from the probability of sation for landslides. These benefits comprise avoided future costs, expressed in today’s val- a substantial part of the overall project benefit. ues using a process of discounting and a dis- To determine costs and benefits, informa- count rate of 12 percent. tion was collected from the community Indirect benefits to the community, relating regarding direct and indirect costs and bene- to improved drainage and installation of roof fits associated with the intervention. This guttering, included improved access (less information was gathered using a question- flooding and fewer debris-blocked paths), naire designed with the help of residents from shorter travel times to work, reduction in another community who were knowledgeable minor damage to homes from flooding and about MoSSaiC—and who distributed the 3 82    C H A P T E R 9.   P RO J E C T E VA L U AT I O N questionnaires and helped residents to com- Baker, J. L. 2000. Evaluating the Impact of plete them. Development Projects on Poverty: A Handbook A sample questionnaire that may be for Practitioners. Washington, DC: World Bank. http://siteresources.worldbank.org/ adapted can be found in Holcombe et al. INTISPMA/Resources/Impact-Evaluation- (2011). The specific information that needs to Handbook--English-/impact1.pdf. be captured by the questionnaire will depend Benson, C., and J. Twigg. 2004. “Measuring on the cost-benefit analysis method used. Mitigation Methodologies for Assessing Natural Seek expert guidance from those knowledge- Hazard Risks and the Net Benefits of able in this field to guide the design of a cost- Mitigation—A Scoping Study.” ProVention benefit model appropriate to the local cir- Consortium, Geneva. cumstances and likely data availability. It is Cairncross, S., and E. A. R. Ouano. 1991. Surface outside the scope of this book to provide Water Drainage for Low-income Communities. guidance beyond illustrating the potential Geneva: World Health Organization and United outcomes of a cost-benefit analysis (section Nations Environment Programme. Cited in 9.5.7); for more information on a MoSSaiC Parkinson 2003. application of cost-benefit analysis, see Hol- Easterly, W. 2002. “The Cartel of Good Intentions: combe et al. (2011). The Problem of Bureaucracy in Foreign Aid Cartel of Good intentions.” Working Paper 4, Results and discussion Center for Global Development, Washington, DC. http://papers.ssrn.com/sol3/papers. The resulting benefit-cost ratio of the land- cfm?abstract_id=999981. slide hazard reduction project was estimated Ganderton, P. 2005. “Benefit–Cost Analysis of to be 1.7:1 without drain maintenance (assum- Disaster Mitigation: Application as a Policy and ing a seven-year drain design life), rising to Decision-Making Tool.” Mitigation and 2.7:1 with proper maintenance (conservatively Adaptation Strategies for Global Change 10: 445– assuming a 20-year design life). 65. The findings of this study should be taken Ghesquiere, F., and O. Mahul. 2007. “Sovereign only as a basis for encouraging further design Natural Disaster Insurance for Developing of appropriate cost-benefit analysis models for Countries: A Paradigm Shift in Catastrophe this type of project, and not as a general confir- Risk Financing.” Policy Research Working Paper 4345. World Bank, Washington, DC. mation of any specific form of intervention. The findings are based on a study undertaken Government of St. Lucia. 2006. “Landslide in a small community of 25 houses in the East- Response Plan.” http://web.stlucia.gov.lc/nemp/ plans/LandslidePlan.pdf. ern Caribbean. The hope is that by illustrating these results from a single small-scale proto- Holcombe, E. A., S. Smith, E. Wright, and M. G. type cost-benefit analysis, the MCU is encour- Anderson. 2011. “An Integrated Approach for Evaluating the Effectiveness of Landslide aged to consider cost-benefit analysis of fur- Hazard Reduction in Vulnerable Communities ther MoSSaiC projects. in the Caribbean.” Natural Hazards. doi:10.1007/ s11069-011-9920-7. 9.7.6 References IPCC (Intergovernmental Panel on Climate Anderson, M. G., and E. A. Holcombe. 2006. Change). 2011. “Definition of Terms Used “Sustainable Landslide Risk Reduction in within the DDC Pages.” http://www.ipcc-data. Poorer Countries.” Proceedings of the Institution org/ddc_definitions.html. of Civil Engineers—Engineering Sustainability 159: 23–30. Lavergne, R. 2004. “Debrief—Tokyo Symposium on Capacity Development, February 4–6, 2004.” Annan, K. A. 1999. “UN Report of the Secretary- Presentation prepared for Canadian General on the Work of the Organization International Development Agency staff. General.” Assembly Official Records Fifty- Fourth Session Supplement No. 1 (A/54/1). —. 2005. “Capacity Development under http://www.un.org/Docs/SG/Report99/intro99. Program-Based Approaches: Results from the htm. LENPA Forum of April 2005.” CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 8 3 Mahmoud, M., Y. Liu, H. Hartmann, S. Stewart, T. Parkinson, J. 2003. “Drainage and Stormwater Wagener, D. Semmens, R. Stewart, H. Gupta, D. Management Strategies for Low-Income Urban Dominguez, F. Dominguez, D. Hulse, R. Letcher, Communities.” Environment and Urbanization B. Rashleigh, C. 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Malone. 1997. “Zen and the Art Countries: Manual. Bonn: Deutsche Gesellschaft of Climate Maintenance.” Nature 390: 332–34 fuer Technische Zusammenarbeit (GTZ) GmbH. Segone, M. 2008. “Evidence-Based Policy Making and the Role of Monitoring and Evaluation Mechler, R., S. Hochrainer, G. Pflug, A. Lotsch, and within the New Aid Environment.” In Bridging K. Williges. 2010. “Assessing the Financial the Gap: The Role of Monitoring and Evaluation Vulnerability to Climate-Related Natural in Evidence-Based Policy Making, ed. M. Segone, Hazards: Background Paper for the World 16–45. UNICEF. http://www.unicef.org/ceecis/ Development Report 2010 ‘Development and evidence_based_policy_making.pdf. Climate Change.’” Policy Research Working Twigg, J. 2004. “Disaster Risk Reduction: Mitigation Paper 5232, World Bank, Washington, DC. and Preparedness.” Development and Emergency Mitchell, T., and M. van Aalst. 2008. “Convergence Programming Good Practice Review 9. of Disaster Risk Reduction and Climate Change UNFCCC (United Nations Framework Convention Adaptation: A Review Paper for DFID.” UK on Climate Change). 2007. “Investment and Department for International Development, Financial Flows to Address Climate Change.” London. http://www.preventionweb.net/ http://unfccc.int/resource/docs/publications/ files/7853_ConvergenceofDRRandCCA1.pdf. financial_flows.pdf. Moench, M., R. Mechler, and S. Stapleton. 2007. —. 2009. “Adaptation to Climate Change: “Guidance Note on the Costs and Benefits of Linking Disaster Risk Reduction and Disaster Risk Reduction.” Prepared for Insurance.” Paper submitted to the UNFCCC UNISDR Global Platform on Disaster Risk for the 6th Session of the Ad Hoc Working Reduction High Level Dialogue, June 4–7. Group on Long-Term Cooperative Action under Nutley, S., H. Davies, and I. Walter. 2002. “Evidence the Convention, Bonn, June 1–12. http://unfccc. Based Policy and Practice: Cross Sector Lessons int/resource/docs/2009/smsn/ngo/163.pdf. from the UK.” Working Paper 9, Economic and UN-Habitat. 2009. Planning Sustainable Cites: Social Research Council, UK Centre for Global Report on Human Settlements 2009. Evidence Based Policy. http://www.unhabitat.org/documents/ OAS (Organization of American States). 2003. GRHS09/FS5.pdf. “Safer and Environmentally Sustainable Wamsler, C. 2006. “Mainstreaming Risk Reduction Low-Income Housing in the OECS through in Urban Planning and Housing: A Challenge Property Insurance and Home Retrofit for International Aid Organizations.” Disaster Programs.” World Bank Contract #7122427, 30: 151–77. OAS, Washington, DC. World Bank. 2003. Strategic Communication for OECD (Organisation for Economic Co-operation Development Projects: A Toolkit for Task Team and Development). 2002. Glossary of Key Leaders. http://siteresources.worldbank.org/ Terms in Evaluation and Results Based EXTDEVCOMMENG/Resources/ Management. Paris: OECD. toolkitwebjan2004.pdf. 3 8 4    C H A P T E R 9.   P RO J E C T E VA L U AT I O N —. 2004. Making Services Work for Poor People. —. 2010b. Safer Homes, Stronger Communities. World Development Report. Washington, DC: A Handbook for Reconstructing after Natural World Bank. Disasters. Washington, DC: World Bank. —. 2007. Introduction to Development Evaluation. Zwane, A. P., and M. Kremer. 2007. “What Works in International Program for Development Fighting Diarrheal Diseases in Developing Evaluation Training. http://www.worldbank.org/ Countries? A Critical Review.” World Bank oed/ipdet/modules/M_01-na.pdf. Research Observer 22 (1): 1–24. —. 2010a. Natural Hazards Unnatural Disasters: The Economics of Effective Prevention. Washington, DC: World Bank. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 8 5 Glossary Abney level. A low-cost instrument used in Bill of quantities. Document containing an topographic surveying to measure slope angle itemized breakdown of the works to be carried in degrees and percentage of grade. The instru- out in a unit price contract, indicating a quan- ment consists of a fixed sighting tube, a mov- tity for each item and the corresponding unit able spirit level connected to a pointing arm, price. and a protractor scale. Building code. A set of standards that specify Acceptable risk. The level of risk loss a soci- the minimum acceptable level of safety for ety or community considers acceptable given buildings or structures. existing social, economic, political, cultural, technical, and environmental conditions. Capacity building. A complex concept that conveys the process by which individuals, Anisotropy. Variation of a physical property groups, and organizations build their knowl- depending on the direction in which it is mea- edge, abilities, relationships, and values in sured. order to solve problems and achieve develop- ment objectives. The impact of capacity build- As Low As Reasonably Practicable ing may thus be seen at different scales—in (ALARP). ALARP risks are those in which the individuals, households, communities, and cost of further risk reduction measures would governments. be grossly disproportionate to the benefits they would deliver. Catchpit. A structure linking inflow and out- flow drains (similar to connection chambers). Baffle. An upstand in the drain intended to reduce flow velocity and water surface super- Catalytic people. In the context of MoSSaiC, elevation on drain bends (likely overtopping). existing staff working in government or rele- vant local agencies who understand the Behavioral change. A change in attitudes and MoSSaiC vision and show an aptitude and a practices of individuals and groups (in the case willingness to participate in its delivery. of MoSSaiC, the desired behavioral change is the adoption of good slope management prac- Certification. The achievement by an indi- tices and policies by communities and govern- vidual against a previously agreed schedule of ments alike). performance, signed off on by government 387 representatives. The term may be varied in dif- surface and surface water, and thus to higher ferent countries for legal or other reasons. downslope pore water pressures. Community. A group of households that iden- Cost-benefit analysis. A systematic calcula- tify themselves in some way as having a com- tion of project cost-effectiveness in terms of mon interest or needs as well as physical space. the balance between the net present value of A social group that resides in a specific locality. project costs and project benefits (discounted over the project lifetime). Project costs and Community engagement. Informing, collab- benefits must be “monetized” (assigned a mon- orating with, involving, consulting, and etary value) for inclusion in the calculation. empowering community members. Direct shear test. A widely used method for Community meeting. Meeting of community determining the shear strength of soils (in residents to discuss any aspect relating to a terms of cohesion and angle of internal fric- project. Such meetings can be formal or infor- tion), first used by Coulomb in 1776. mal, depending on the nature of the commu- nity and what works best for the residents in Disaster risk management. An understand- terms of timing and venue. ing of what processes and factors contribute to risk, sufficient that management of the risks Community contracting. Procurement by or can be undertaken. on behalf of a community. While there are many different models of community con- Divergence (of a slope). When viewed in tracting, a common feature is that they seek to plan, orthogonals to the ground contours give the community varying degrees of control diverge in the downslope direction. This situa- over investment and implementation, which it tion is conducive to the divergence of subsur- is hoped will encourage ownership and sus- face and surface water, and thus to lower tainability. downslope pore water pressures. Connection chamber. A reinforced concrete Double-handling costs. Additional costs vault (with height, width, and depth of incurred when construction materials cannot between 300–500 mm each) allowing inflow be delivered directly to site due to limited from one or more pipes carrying household access. The material is instead manually trans- gray water and roof water, and outflow via a ported between the point of delivery, an inter- single pipe to a nearby main drain or another mediate storage site, and the construction site. connection chamber. The top of the chamber is usually flush with the ground surface and Elements at risk. Such as people, communi- covered with a concrete slab that can be ties, agricultural areas, roads, facilities (e.g., removed to allow access for maintenance and hospitals, schools), utilities (e.g., water mains, cleaning. power lines, power stations), economic/indus- trial infrastructure (factories, mines). Consequences. The outcome of an event such as a landslide hazard occurring. Dependent on Erosion (soil). The gradual wearing away of the exposure and vulnerability of the elements soil by an agent such as water or wind, and its at risk (e.g., people, houses, infrastructure). loss, particle by particle. Convergence (of a slope). When viewed in Evidence-based policy. A policy process that plan, orthogonals to the ground contours con- helps make better-informed decisions by put- verge in the downslope direction. This situa- ting the best available evidence at the center of tion is conducive to the concentration of sub- the policy process. 3 8 8    G LO S S A RY Exposure. The location of elements at risk Hurricane strapping. Typically, galvanized with respect to a specific hazard. strapping bars of various shapes to affix roof timbers to wall plates to ensure the stability of Ex ante measures. Measures taken before a the entire roof structure during high winds. disaster in the expectation that they will either prevent, or significantly reduce the impact of, Intercept drain. A drain running almost par- a possible disaster. allel to slope contours (but with a slight down- slope gradient) to capture water flowing down Ex post measures. Measures taken after a the slope. disaster has occurred to seek to make good all related damage caused by the disaster. Key performance indicators (KPIs). Quan- titative and qualitative measures of project Factor of safety. The ratio of shear strength outputs and outcomes used to evaluate the (acting so as to resist slope failure) of a soil to progress of success of the project. the shearing force (tending to induce slope fail- ure) experienced by slope material. A factor of Landowners. Those who “own” the land safety < 1 indicates potential slope instability. upon which MoSSaiC project construction takes place. Note that landownership may be Focus group. A small number (typically difficult to establish, landowners may not around 10) of individuals who provide infor- reside within country, and landownership may mation during a directed and moderated inter- be disputed—refer to any relevant safeguards. active group discussion. The purpose is to sub- ject ideas to review by the group in order to Landslide hazard. The probability of occur- determine the viability of those ideas. rence of a landslide of a specific type and mag- nitude in a particular location. Geographic information system (GIS). Any system that captures, stores, analyzes, man- Landslide risk. A function of landslide haz- ages, and presents data that are linked to their ard, exposure, and vulnerability—communi- geographical location. ties with relatively high landslide risk will be those where high landslide hazard coincides Gray water. Gray water is all nonseptic waste with high-level exposure (e.g., dense housing) from houses, typically including water from and high socioeconomic vulnerability. washing machines, showers, and kitchen sinks. Landslide susceptibility. The propensity of an area to experience landslides—the inherent Hazard. A process that has the potential to instability of a slope. cause damage (e.g., landslide). Low-cost drain. Non–concrete block drains Hazard map. A map showing areas affected constructed using polythene and galvanized by a particular hazard, such as landslides. mesh for lining an excavated drain trench. Espe- cially useful for small drains conveying low-vol- Herringbone drainage. A drainage pattern ume or low-velocity flows, and where the deliv- that is frequently used to drain hillsides, most ery of cement and blocks may be difficult. commonly for cut-slopes in highways. It com- prises a central downslope drain with feeder MoSSaiC core unit (MCU). The main man- intercept drains running to either side. agement coordinating body for MoSSaiC interventions, comprising within-country Heterogeneity. Exhibiting diverse (non- “catalytic” individuals from different govern- homogeneous) properties. ment ministries, agencies, and related bodies. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 8 9 Mitigation. The lessening of the adverse interact with different government team impact of hazards or disasters. members over the course of a MoSSaiC project and should be able to identify “who is respon- Point sources. Sources of water that have a sible for whom about what.” specific point of discharge onto a hillslope, such as gray water discharge from a house or Resilience. The ability of a community or an unlined drain. society potentially exposed to hazards to resist, absorb, adapt to, and recover from the Preparatory factors. Factors that can have a stresses of the hazard event. Often referred to potential role in slope instability. as the converse of vulnerability. Project outcomes. Medium-term, post- Resistance envelope. A means of assessing implementation results of a project. the threshold soil water conditions for stabil- ity, typically used to determine whether the Project outputs. Results of a project that are maintenance of negative pore pressures is measurable at the immediate point of project required for a slope to remain stable. This completion. technique also enables the likely slope failure depth to be identified. Project step template. The document that sets out the initial project steps for a MoSSaiC inter- Resolution. The accuracy at which a given map vention and which the MCU has the responsi- scale can depict the location and shape of map bility of refining to suit local conditions. features; the larger the map scale, the higher the possible resolution. As map scale decreases, res- Rainfall threshold. A threshold measure of rain- olution diminishes and feature boundaries must fall (typically duration and depth or intensity) be smoothed, simplified, or not shown at all. It is that, if exceeded, has been shown empirically to the size of the smallest feature that can be repre- be associated with the occurrence of landslides. sented in a surface. For example, small areas may have to be represented as points. Rational method. A widely used equation to estimate water discharge, being a product of Retrofitting. Reinforcement or upgrading of rainfall intensity, hillslope contributing area, existing structures to make them more resis- and a runoff coefficient. tant and resilient to hazards. Recurrence interval. Time between hazard Risk. With respect to disasters, a function of events of similar size in a given location based the hazard, exposure, and vulnerability. A on the probability that the event will be measure of the likelihood of damage. equaled or exceeded in a given period (typi- cally a year). Thus a 30-year event is one that is Risk analysis. The process of hazard, expo- likely to occur once every 30 years. sure, and vulnerability identification and risk estimation. This may be qualitative—landslide Reporting lines. The way people participat- probability, exposure, and vulnerability of ing in a project are organized. Individuals exposed elements expressed in relative terms; responsible for a specific aspect of project semi-quantitative—indicative probability or delivery should be assigned to a supervisor or relative vulnerability; or quantitative—numer- line manager to ensure that they are fully sup- ical probability and loss measures. ported (technically and operationally) and accountable in their role. Clear reporting lines Risk drivers. Factors that serve to promote a are particularly important for community- potential increase in the level of risk (e.g., rain- based projects. Community residents will fall, discharge of water onto hillslopes). 3 9 0    G LO S S A RY Scale (of maps and plans). The scale of a map Unacceptable risk. The level of risk that soci- or plan is defined as the ratio of a distance on ety is not prepared to accept. the map to the corresponding distance on the ground. Scales are often qualified as small Unauthorized housing. Housing not in com- scale, typically for large regional maps, or large pliance with current regulations concerning scale, typically for county maps or town plans. landownership, land-use and planning zones, or construction. Safeguards. Requirements, protocols, guid- ance notes, etc., from funding agencies, gov- Vulnerability. The potential degree of dam- ernments, and other such bodies that define age or loss experienced by the exposed ele- ways of working that the MCU, and all con- ments for a given landslide event, usually cerned with a MoSSaiC intervention, should expressed on a scale of 0–1 (no damage to total both take note of and adhere to wherever they loss). With respect to urban landslides, dam- are deemed or shown to be relevant. age can be thought of as direct or indirect, physical (loss of life, homes, or property), or Shear strength. The resistance to deforma- socioeconomic (loss of livelihoods, loss of tion by continuous shear displacement of soil assets). particles along a surface of rupture. Vulnerable community. With respect to Show home. A home within a community in MoSSaiC, a community that can be considered which drainage provision is configured to pro- likely to be significantly physically and socio- vide an example of good practice to the rest of economically damaged by a landslide. It will the community. have low resilience to such an event and will find it difficult to recover. Poverty may be used Squatter housing. Housing occupying land as an indicator of vulnerability and resilience. illegally. Different countries will be expected to apply different measures to assess vulnerability to Stakeholders. Groups who have any direct or identify and prioritize communities for indirect interest in the MoSSaiC intervention, MoSSaiC projects. or who can affect or be affected by the imple- mentation and outcomes, including such Weathering. The physical and chemical alter- groups as those undertaking, managing, ation of minerals into other minerals by the reporting on, affected by, promoting, and fund- action of heat, water, and air. ing the interventions. Weathering grades. A scale describing the Strategic incrementalism. An approach to level of weathering of a rock mass, typically changing practice and policy that is incremental. divided into six classes (fresh rock being grade  I; fully weathered soil being grade Tolerable risk. A risk that society is willing to VI). live with so as to secure certain benefits in the confidence that it is being properly controlled, Work package. The complete specification of kept under review, and further reduced as and works to be completed by a contractor. This when possible. should specify the detailed nature of the works to be undertaken with clear indication of Triggering event. A natural (e.g., rainfall, extent marked on the ground on site, as well as seismic, volcanic) or human-induced (e.g. on the drainage plan. Design drawings and slope loading, slope cutting) event that results similar specifications should be included as in the occurrence of a landslide. part of the package. CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 9 1 Index Figures and tables are indicated by f and t, fol- adapting the MoSSaiC blueprint to existing lowing the page numbers. capacity, 309, 311 adoption of change, 309–15, 311t behavioral change process, 309–11, 312f A combining knowledge and action, 314–25 Abney level, 103, 104f, 387 learning by doing, 315, 316t “acceptable risk,” 13–14, 15f, 387 stakeholder perceptions, 312–14 accumulation of risk, 10 vulnerability and risk perception, 313 Active Learning Network for Accountability and briefing note, 306–7 Performance in Humanitarian Action, building local capacity, 307, 329–34, 330t 170 communities, 332–33, 333f adapting the MoSSaiC blueprint to existing examples by learning mode, 330t capacity individual expertise and skills, 330–31, behavioral change, 309, 311 331f community-based mapping, 170, 171 politicians, 331–32, 332f drainage design, 216–17 teams, 331, 332f implementation of planned works, 266, 267 user groups, 333–34, 334f landslide hazards, 85, 86 communication forms and project messages, prioritizing of communities at risk, 132, 133 317–29. See also communication project evaluation, 350, 351 communication strategy, 306–7, 315–17, 316t project inception, 58–60 community-based aspects, 306 advocacy task team, 69–71, 71f defined, 387 Alwi, S., 260 finalizing integrated strategy, 334–39 Anderson, M. G., 114 adoption of good drain maintenance angle of internal friction, 99-100, 105, 117, 120-23, practices, 334–35 195t. See also shear strength assignment of maintenance responsibility, anisotropy, 199, 387 335–36, 336f anthropogenic contributors to landslide risk, integration of strategy, 338–39, 339t 27–28, 28f, 168 structural inspections and community Ardizzone, F., 97 clean-up days, 336–37, 337f Arias, A., 90, 91t guiding principles, 307–8 Arnstein, S. R., 172 high staff turnover, 308–9 As Low As Reasonably Practicable (ALARP), 14, key elements, 305–6 387 project inception creating platform for, 58 risks and challenges, 308–9 B who does what, 340 baffles, 255, 255–59f, 387 benefit-cost ratio 18f, 19f 27f, 353, 382f. See also Barker, D. H., 294 cost-benefit analysis base map, 140, 159-60, 160f, 169, 178. See also bill of quantities, 268–69, 269–70f, 269t, 387 community-based mapping bioengineering 292-294, 295t, 296f behavioral change, xxviii, 305–43 Binswanger-Mkhize, H. P., 42 3 93 Bishop, A. W., 101, 114, 116 adapting the MoSSaiC blueprint to existing Bishop method, 100 capacity, 132, 133 Bishop stability equation, 120 base map preparation for detailed community black water. See septic waste mapping, 159–60, 160f Blake, J. R., 122 briefing note, 130–31 Brooks, S. M., 114 combining hazard and vulnerability Buchanan, J. M., 61 information, 157 budget constraints, 7 community-based aspects, 130 building code, 227, 323, 370, 387 confirming selection, 156–58, 157t guiding principles, 131 C interpreting landslide hazard maps, 132 Campbell, S., 294 key elements, 129–30 capacity building. See also adapting the MoSSaiC landslide susceptibility and hazard blueprint to existing capacity assessment methods, 140–51, 142t defined, 387 deterministic methods, 150–51 government capacity, 34 field reconnaissance and hazard ranking local capacity, 309, 329–34 methods, 141–46, 143f, 144–45t Caracas, República Bolivariana de Venezuela, GIS-based qualitative landslide unauthorized housing in, 25 susceptibility mapping, 146–49, Caribbean. See Latin America and the Caribbean 155–56 Caribbean Catastrophe Risk Insurance Facility, 19 probabilistic approaches, 149 catalytic people, xxv, 4, 43, 387 semi-quantitative and quantitative, 149–51 catchpits, 255, 255–59f, 387 statistical methods, 149–50 categories of disasters, 9, 9t psychological barriers of, 6–7 certification process for MoSSaiC, 341–42, 387 risks and challenges, 131–32 CHASM (Combined Hydrology and Slope selection process, xxvi, xxix, 44–45, 132–40, Stability Model), 113–15, 114–16f, 120, 135t 121t, 134, 194, 196, 201, 201f bivariate and multivariate statistical Chowdhury, F., 146 approaches, 134 clean-up days, 336–37, 337f choice of risk comparison approach, 135– climate change, 23 36 climate proofing, 370, 371t, 373 comparison of risk at multiple locations, cohesion, 99-100, 105, 117, 120-23, 195t. See also 134–36 shear strength data and analysis methods for, 137–38, 138t communication deterministic spatially distributed briefing key leaders about MoSSaiC, 47 modeling, 134 clear project messages for stakeholders, 308 digital data and GIS analysis, 132, 134 community demonstration sites and show field reconnaissance and risk ranking, 134 homes, 321–23, 322f, 322t, 391 heuristic methods, 134 community involvement methods, 174–75 MCU agreement to, 138–39 defining communication purposes and methods for, 136–39, 137f functions, 317 probabilistic methods, 134 delivering project messages, 322–24, 325f short-term planning of, 7 direct communications, 320–21, 320t situational barriers of, 6–7 examples of communication mode, channel, size of cities and, xxiii and purpose, 318t vulnerability assessment, 151–56, 152t finalizing project messages, 329 defined, 12 focus groups, 177, 177f, 389 exposure, 151 forms and project messages, 317–29 field reconnaissance and vulnerability in government-community partnerships, 34 ranking methods, 153–54, 154– identifying audiences, 317, 318t, 319t 55t meetings. See community meetings GIS-based mapping for, 155–56 MoSSaiC information materials, 323 who does what, 161 relevance, 308 community-based approach, 3, 4f, 26t, 29–34. See scientific and professional publications, 328– also community engagement; specific 29 topics timing of media reports, 308 behavioral change, 306 TV, radio, and newspaper coverage, 324–28, communities at risk, prioritizing of, 130 327–28t, 327f community-based mapping, 166, 169–70 written and visual materials for communities, coping mechanisms, 30, 31t 323–24, 324t, 326f definition of community, xxiii, 388 communications task team, 69, 70f drainage design and good practice, 214 communities at risk, prioritizing of, 2, 3f, 129–63 government-community partnerships, 34 3 9 4    I N D E X implementation of planned works, 262 collaborative approaches, 170, 172 landslides as community issue, 4, 23 community-based mapping requiring, 166, mapping. See community-based mapping 169–70 MoSSaiC’s approach to, 5–6, 32–33 defined, 388 teams. See community task teams how to work within a community, 170–78 community-based mapping, xxvi–xxvii, 165–210, avoiding bias and considering interests of 204f all groups, 175–76 adapting the MoSSaiC blueprint to existing community leaders’ involvement, 47, 175 capacity, 170, 171 culture and diversity, 172–73 base map preparation for detailed mapping, formal meetings, 177–78, 178f 159–60 gender relations, 173–74, 173f, 174t briefing note, 167–68 house-by-house discussions, 176–77, 177f community-based aspects, 166, 169–70. See informal focus groups, 177, 177f also community engagement interactive process, 176 community knowledge and gaining listening to residents, 175 acceptance, 176–78 practices and communication methods, connecting with key community members, 174–75 169, 175 types of participation, 170, 172, 172t defined, 167 instrumental approaches, 170 guiding principles, 168–69 mapping. See community-based mapping identification of landslide hazard zones, 189– practices, 174–76 91, 192f, 193t principles, 170–74 information to be included, 168 selection of community. See communities at key elements, 165–66 risk, prioritizing of physically based landslide hazard assessment, stakeholders, 44, 44t 191–93, 194t, 202t supportive approaches, 172 pore water pressure, 88, 99-101, 105-108, 114- community leaders’ involvement, 47, 175 20, 198 community liaison task team, 67, 68f, 140, 174 purpose of, 167, 168 community meetings, 177–78, 178f, 388 qualitative landslide hazard assessment, 188– community task teams, xxx–xxxi, 5t, 43, 71–74, 75f 91, 190f concave downslope profile, 179, 180f repeating survey, 188 concrete drains. See drainage design and good risks and challenges, 169–70 practice scientifically based justification, 189 connection chambers, 248, 249f, 284, 285f, 388 slope features, 178–88, 187f consequences, 388. See also cost-benefit analysis; accuracy of map, 187–88 fatalities and losses alterations to natural drainage, 181–82, 182f damages exceeding 1 percent of GDP, 41f evidence of slope movement, 185–87, 186f outputs and outcomes as evidence of hillside scale, 178–82, 179f, 183t effectiveness, 34, 35t, 390 household drainage, 184–85, 184–85f unintended, 335, 335f household-scale contributors, 182–85, construction task team, 73, 73–74f 185t, 187f contracts, tendering process, 276–77 local knowledge of past landslides, 185 convergence zones, 179–80, 180f, 388 local slope geometry and material, 183–84, Coppin, N. J., 294 183f corruption, 300–301 seepage zones, 181, 181f cost-benefit analysis, 18–19, 18–19f, 365–67, 381–83, slope angle. See slope angle 382f, 388 slope stability issues, 185–87, 187t Craig, R. F., 122 slope stability models, 194–98, 195–98f, Crozier, M. J., 21 195t. See also CHASM Cruden, D. M., 91 (Combined Hydrology and Cuba’s National Landslide Risk Assessment Slope Stability Model) Project, 148–49, 149f topography and natural drainage, 169, 179, cultural differences, 172–73 179–80f timing of visits and meetings with residents, D 169, 188 debris traps, 235–36, 235f, 335 topographic features to be identified at clearing, 336–37, 337–38f necessary resolution, 169 construction, 298–99, 298–300f zones for drainage interventions, 203 demonstration sites and show homes, 321–23, community clean-up days, 336–37, 337f 322f, 322t, 391 community contracting, 264–65, 264f, 265t, 388 Department for International Development (UK), community engagement 128 benefits of, xxi–xxii, 2, 4, 4f, 32–34, 33t de Regt, J. P., 42 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 9 5 desk studies, 194 currently active landslide sites, 221–22, Dietrich, W. E., 150 222f disaster risk, 7–25 currently inactive landslide sites, 220–21, “acceptable risk,” 13–14, 15f 222f categories of disasters, 9, 9t estimation of house discharge, 226–29 definition of risk, 11–14 estimation of main drain dimensions, 227 future scenarios 374, 376-78, 377f estimation of surface water discharge, increases in costs of, 8, 8–9f 223–26, 225t increases in number of, 7–8, 8f idealized alignment, 219–20, 220f insurance, 19–20, 19f impact of household water, 229, 230f landslide risk, 9–10. See also landslide hazards intercept drain effectiveness, 227–29, management. See disaster risk management 228–29f (DRM) linear drain alignment and easy access, records of disasters, 9 220, 220f disaster risk management (DRM), 11–14, 14f patterns and principles, 218–22 assessment, 12. See also science-based approach alterations to natural drainage, 181–82, 182f benefits of, xxi, 2, 18 assignment of maintenance responsibility, catastrophe risk models, 18 335–36, 336f definition of, 11–12, 388 briefing note, 214–15 disaster risk insurance, 19–20, 19f capacity, 218 evidence of project’s effectiveness. See channel slope, 218 evidence base of effectiveness community-based aspects, 214 exposure, defined, 12 community slope feature map as part of, 167 hazard, defined, 11–12 connectivity, 218 influences on, 14–23 drain specifications, 236–42, 240–42f, 243t international advocacy groups, 15f drain performance, 362, 362f national and local studies, 21 drain types, 229–36, 231f social funds, 21–23, 22f downslope drains, 232, 232f UN disaster response organizational footpath drains, 232–33, 233f framework, 16f incomplete existing drains, 233–34, 234f process and steps involved, 12–13, 13t incorporating debris traps, 235–36, 235f recent influences on, 14–23 intercept drains, 227–29, 228–29f, 231–32, reduction (DRR), 13, 307. See also disaster risk 231f, 389 mitigation placement above landslides to stabilize top-down evaluation, 349–50 slope, 234, 235f science-based approach. See science-based easy drain maintenance, 215–16, 334–35 approach effectiveness of drains, xxv shift from ex post to ex ante policies, 14–17 gray water management, 216, 246–47, 246f. vulnerability, defined, 12 See also gray water management disaster risk mitigation guiding principles, 215 benefits of, 2, 3f, 18–19, 18–19f household water capture, 218, 242–50, 282–84 definition of mitigation, 390 connection to drainage network, 247–48, need for evidence of benefits of, 17–19. See also 247–49f evidence base of effectiveness hurricane strapping, 249, 250f, 389 psychological barriers to, 6–7 rainwater harvesting, 244–47, 245–46f scope of, 13 roof guttering, 242, 244, 244f, 282, 283f situational barriers to, 6–7 importance of good design, 215 divergence of a slope, 388. See also slope angle key elements, 213–14 Dominica, impacts of community-based risk local designs for concrete drains, catchpits, reduction program in, 34, 35t and baffles, 255, 255–59f double-handling costs, 226, 271, 274, 275, 388 locations chosen to reduce landslide hazard, 216 double or triple wedge analysis, 100 low-cost drains, 298–301, 389 downslope proposed drainage plan, 236, 237f, 238t concave downslope profile, 179, 180f reinforced concrete block drains, 238–39, 239f drains, 232, 232f risks and challenges, 215–16 drainage design and good practice, xxvii, 213–59 signing off on final drainage plan, 250-51 adapting the MoSSaiC blueprint to existing community agreement, 251, 252–53f capacity, 216–17 formal approval, 253 alignment of drains, 217–29, 219f slope stability and, 107–8 calculation of drain flow and dimensions, who does what, 254 222, 223f, 224t zones for interventions, 203–7 complex topography and difficult access, assigning intervention to each zone, 203, 220, 221f 205 3 9 6    I N D E X assigning priorities to different zones, G 206–7, 207t gender relations, 173–74, 173f, 174t drawing initial drainage plan, 205–6, geoscience, 20. See also science-based approach 205–6f GIS-based mapping drain types. See drainage design and good definition of GIS, 389 practice for landslide susceptibility assessment, 95–96, drainage plan 97f, 132, 134, 146–49 initial, 178, 188, 203, 205–7, 205f for vulnerability assessment, 155–56 proposed, 207, 219f, 236, 237f, 238t spatial scale, 21, 28, 84 final, 188, 204f, 215-16, 219f, 236, 237f, 250-52, Glade, T., 21 252f “good Samaritan” approach, 7, 61, 61t DRM. See disaster risk management Goodwin, C. N., 150 Dumsi Pakha, potential applicability of MoSSaiC government principles and methods to, 41, 41f capacity building, 34 -community partnerships, 34 E expertise, engaging in risk reduction earthquakes, 87–91 measures, xxi, 2, 4, 4f Easterly, W., 42, 347 task teams, xxx, 5t, 34, 43, 65–71, 66t, 75f, 175, economic effects of disasters, 8, 8–9f. See also 307, 313 consequences; cost-benefit analysis Gray, D. H., 294 elements at risk, 20, 135t, 152t, 388. See also gray water management, 25, 108, 115, 182, 184, 188, vulnerability 198, 216–18, 240f, 246–47, 246f, 282, 282f, 389. El Salvador earthquakes, 89, 91f See also drainage design and good practice Emergency Events Database (EM-DAT), 9 Green, R., 29 engineering task team. See landslide assessment Guatemala City, aid distribution in, 29, 30f and engineering task team environmental factors. See slope angle; slope H stability; soil parameters Hampson, K., 260 environmental health benefits, 362–64 Harp, E. L., 150 erosion, 144t, 179–82, 292, 388. See also landslide hazards. See also landslide hazards hazards; slope stability catastrophe modeling for, 18 evaluation. See project evaluation defined, 11–12, 389 evidence base of effectiveness, xxii, 3–4, 4f, 6, drivers of, 22 17–19, 22, 26t, 34, 35t, 388 HDI (Human Development Index), 155 ex ante measures, 14–17, 389 helplessness in face of risk, 7 ex post measures, 14–17, 389 herringbone drainage, 219, 220f, 389 exposure High, C., 21 defined, 12, 389 Holcombe, E. A., 194, 381 landslide risk, 83, 151 holistic awareness of slope processes, 84–85 Holmes, John, xxxviii F Honduras, debris flow hazard in, 150–51, 150f factor of safety, 99–100, 114, 115, 197–98, 198f, Hong Kong SAR, China 201–3, 201f, 389 “acceptable risk” defined in, 14, 15f failure surface, of a landslide, 99, 100, 197 bioengineered slope in, 296f fatalities and losses, 9–10, 10–11f, 23, 83, 87–91, 120, debris traps, use of, 235, 235f 167–68 Geotechnical Control Office on retaining wall damages exceeding 1 percent of GDP, 41f adequacy, 123 Fell, R., 145 Geotechnical Engineering Office, example Fellin, W., 200 of field reconnaissance and hazard field reconnaissance and hazard ranking methods, ranking methods, 145–46 134, 141–46, 143f, 144–45t, 153–54, local preparatory factors and landslides in, 93 154–55t site inspections finding inadequate drainage, Finlay, P. J., 145 288, 290f Flentje, P., 146 house-by-house discussions, 176–77, 177f flooding, 31t, 35t, 185t, 185-88, 206t, 230, 238, 280, housing 282, 289t, 292t, 371t connection of household water to drains, focus groups, 177, 177f, 389 284–85, 284–85f footpath drains, 232–33, 233f, 289–90, 291f cracks in houses, 358–60, 361f, 379–80, 380f funders density, 29, 151 advocacy landscape, 15f estimation of house discharge, 226–29 key role of, xxix household drainage, 184–85, 184–85f social funds, 21–23, 22f household water capture, 218, 242–50, 282–84 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 9 7 impact of household water, 229, 230f wasted materials and no surface water unauthorized housing, 10, 24, 25t, 28, 108, capture, 288, 290f 109f, 391 preparation of work packages, 266–73, 391 Howell, J., 294 bill of quantities, 268–69, 269–70f, 269t, Human Development Index (HDI), 155 387 hurricanes. See also disaster risk compilation of documents, 272–73 Hurricane Allen’s impact on St. Lucia defining work packages, 271–72 economy, 40, 41f. See also St. Lucia detailed construction specifications, 272, Hurricane Mitch debris flows, 151 273t Hurricane Tomas over Eastern Caribbean, 103f procurement plan, 272 risk management components of, 18–19, 18–19f processes and good practices, 263–64, 263f hurricane strapping, 249, 250f, 389 project interruptions, 265–66 hydraulic conductivity, 102, 106, 115, 195t questionable practices, 266 hyperbolic discounting of risk, 7, 313 risks and challenges, 265–66 signing off on completed works, 291–92 tendering process, 274–77 I briefing potential contractors, 274–76, implementation of planned works, xxvii–xxviii, 274–76f 261–302 evaluating tenders and awarding adapting the MoSSaiC blueprint to existing contracts, 276–77 capacity, 266, 267 identifying contractors, 274 briefing note, 262–65 questionable or corrupt practices, 300– community-based aspects, 262 301 community contracting, 264–65, 264f, 265t, 388 safeguard policies, 277, 277f, 277t debris trap construction, 298–99, 298–300f who does what, 297 drainage construction, 262–63 India good practices, 285–88 potential applicability of MoSSaiC principles access for residents, 287, 287f and methods to, 41, 41f casting concrete in good weather, 285, urban infrastructure projects in, 264–65 286f inspections inventory control, 287 site inspections finding inadequate drainage, reduced leakage from pipes, 288, 288f, 288, 290f 289t structural inspections and community clean- secure storage of materials, 287 up days, 336–37, 337f guiding principles, 265 insurance inadequate contractor briefing, 266 Caribbean Catastrophe Risk Insurance key elements, 261–62 Facility, 19 low-cost appropriate construction methods, connecting hazard reduction and, 371–74, 298–301 372–73t, 372f, 376t on-site requirements, 278–85 disaster risk, 19–20, 19f capture of household roof water, 282–84 insured losses, 8f, 9t, channel gradient issues, 280–81, 281f intercept drains, 227–29, 228–29f, 231–32, 231f, connection of household water to drains, 389 284–85, 284–85f International Union of Geological Sciences drain effectiveness, 281–82 Working Group on Landslides, 13 drain walls, 281, 282f Italian Istituto di Ricerca per la Protezione excavation and alignment requirements, Idrogeologica (IRPI), 120 279–81, 280f Italy, direct landslide mapping in, 97, 98f roof guttering, 282, 283f site supervision, 278–79, 278–79f water tank overflows, 285, 286f J weep holes, 281–82, 282f Janbu, N., 101, 114 poor supervision and rushed work, 266 Johari Window, 312–13, 313f, 317 postconstruction bioengineering, 292–96 decision aid for choosing technique, 295t K definition of bioengineering, 293, 293f Keefer, D. K., 90 vegetation’s effect on slope stability, 293– key performance indicators (KPIs), 346, 350, 351, 94, 294f 354, 354–56t, 389 practices to be avoided, 288–91, 290f, 292t Knutson, T. R., 23 hazardous access for residents, 291, 291f Ko Ko, C., 146 questionable or corrupt practices, 300–301 Konietzky, H., 106 restricted capacity of footpath drains, Kosugi, K., 106 289–90, 291f Kunreuther, H., 304 3 9 8    I N D E X L small retaining walls, inadequacy of, 117– laboratory and field measurements, 194 18, 118f, 122–23, 122f land-locked developing countries, 40 seismic events, 89–91, 91f landowners, 73–74, 389 slope movement and landslide material, 85–87 landslide assessment and engineering task team, slope stability and. See slope stability 68, 68f, 140, 201–2, 202f, 203, 291 susceptibility, 95, 96t, 140, 141 landslide hazards, xxv–xxvi, 81–127, 141 types of landslides, 85–92. See also rotational accumulation of risk, 10 slides; translational slides adapting the MoSSaiC blueprint to existing understanding landslide processes, 82–83 capacity, 85, 86t who does what, 119 aggravating factors, 93, 94t landslide risk drivers assessment of, xxvi definition of landslide risk, 389 community-based mapping for. See Eastern Caribbean, 35–36, 40f community-based mapping longer term, 370–78 scientific methods for, 112–18 MoSSaiC targeting, 23–25, 40f briefing note, 82–83 physical, 22, 26-27 community-based aspects, 82 science-based approach, 28 as community issue, 4. See also communities urbanization, 2, 10, 23-25, 89, 108, 374 at risk, prioritizing of; community- vulnerability and, 22 based approach Latin America and the Caribbean. See also specific as component of landslide risk, 83 countries construction on former landslide zones, 111, Caribbean Catastrophe Risk Insurance 113f Facility, 19 coupled dynamic hydrology and slope Caribbean regions vulnerable to natural stability models, 113–15 disasters, 36, 41f dynamic hydrology component, 114 Eastern Caribbean typical communities and interpreting simulation results, 115 risk drivers, 35–36, 40f model configuration, 114 housing density in, 29 slope stability component, 114 La Red studies of disasters, 9 defined, 389 MoSSaiC development in, 10–11 direct landslide mapping, 97–98 pilots, 35–41, 40t empirical rainfall threshold modeling, 98–99, rainfall-triggered landslide risk in, 9 99f learning by doing, xxiii, 169, 307, 314-17, 319, 329, fatalities and losses associated with, 9–10, 330t, 339t 10–11f, 23, 83, 87–91, 120, 167–68 lessons learned geometry and features of landslides, 87, 88f in disaster risk management, xxv GIS-based susceptibility mapping, 95–96, 97f, failure to apply from past disasters, 7 132, 134 from World Bank natural disaster projects, guiding principles, 83–84 17–18, 17t holistic awareness of slope processes, 84–85 limit equilibrium method, 99-101 identifying, xxvi, 10–11, 84–85 loading and slope stability, 111–12, 112f instability and. See slope stability logframe format, 45, 47t key elements, 81–82 Londell, M. K., 61 lack of awareness of risk, 7 low-cost drains, 298–301, 389 as management issue, 4 Lundgren, R. E., 323 mapping of. See community-based mapping; mapping M physically based slope stability modeling, macrofinancing disasters, 374, 376f 99–101 Mahmoud, M., 377 preparatory factors and triggering Malone, E. L., 30 mechanisms, 87–91, 93, 94t, 102f, management issue, landslide hazards as, 4. See 390 also government expertise, engaging in probability, 95 risk reduction measures rainfall and earthquakes, 87–91 mapping reduction practices, 367–69 community-based. See community-based regional policies and, 84 mapping risks and challenges, 84–85 direct landslide mapping, 97–98 science-based approach, 20, 83, 84t, 112–18. See GIS-based landslide susceptibility mapping, also CHASM (Combined Hydrology 95–96, 97f, 132, 134, 146–49 and Slope Stability Model) landslide hazard map, 147, 389 resistance envelope method for national risk maps, 21 determining suction control, resolution of maps, 21, 67, 132, 149, 169, 390 116–17, 117f task team, 67, 67f, 140, 159, 178 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    3 9 9 wide-area landslide hazard mapping, 21, 167 premises, 4f Maskrey, A., 21, 54 project inception, xxv, 55–79. See also McMakin, A. H., 323 MoSSaiC teams; project inception media purpose of, xxi timing of media reports, 308 risks and challenges, 6–7 TV, radio, and newspaper coverage, 324–28, science based, 3, 4f, 26–29. See also science- 327–28t, 327f based approach Meyer, R. J., 17–18 teams and tasks, 5t. See also MoSSaiC teams Miles, S., 29 vision, xxv, 3, 4–5, 4f, 11 Millington-Quirk equation, 120 MoSSaiC core unit (MCU). See MoSSaiC teams models MoSSaiC teams, xxv, 42–44, 65–71 catastrophe risk models, 18 advocacy task team, 69–71, 71f CHASM. See CHASM (Combined Hydrology capacity building, 331, 332f and Slope Stability Model) communications task team, 69, 70f coupled dynamic hydrology and slope in communities selection process, 140 stability models, 113–15 community liaison task team, 67, 68f, 140, 174 physically based landslide hazard assessment, community task teams, xxx–xxxi, 5t, 43, 71–74 191–93, 194t, 196f community residents’ responsibilities, shallow landsliding model (SHALSTAB), 150 71–72, 72f slope stability models, 134, 194–98, 195–98f, construction task team, 73, 73–74f 195t landowners, 73–74, 389 Stability Index Mapping (SINMAP) model, developing and engaging, 58 150 government task teams, xxx, 5t, 34, 43, 65–71, threshold modeling, 98–99, 99f 66t, 175, 307, 313 uncertainty associated with model integration of teams and tasks, 5t, 74–77, 75f, formulation, 200–201 76–77t Mohamed, S., 260 landslide assessment and engineering task Mohr-Coulomb equation, 114, 120 team, 68, 68f, 140, 201–2, 202f, 291 Montgomery, D. R., 150 mapping task team, 67, 67f, 140 mosquito breeding habitats, 364f MoSSaiC core unit (MCU) MoSSaiC (Management of Slope Stability in in communities selection process, 138–40, Communities) 158, 158t adapting the blueprint, xxiv, xxx, 5, 6, 22, 42 community participation, 174 applicability to locations outside of Eastern defined, 389 Caribbean, 41, 41f establishment of, 57, 60–65 briefing key leaders about, 47 expertise and building capacity, 60, 60t certification, 341–42, 387 in-country management practice, 61 commencing intervention with, 42–47 membership of, 65, 66t community based, 3, 4, 4f, 23, 29–34. See also missions of, 61–65, 63f community engagement policy entrepreneur role, 61, 62t context for, xxii–xxiii, xxv, xxix, 22 role of, xxix–xxx, 43, 56–57, 62–65 designed for effectiveness, 22 template of teams, steps, and milestones, 76–77t Eastern Caribbean typical communities and technical support task team, 69, 69f, 140 risk drivers, 35–36, 40f who does what, 48, 66t, 78 evidence based, xxii, 3–4, 4f, 6, 22, 34 Mostyn, G. R., 145 foundations of, xxv, xxix, 1–2, 4f, 26, 26t. See also community-based approach; N evidence base of effectiveness; Nandi, A., 95 science-based approach National Research and Development Foundation, framework and components, xxv, 22–23, 373 34–35, 36–40t getting started, 2–7, 42–48. See also project inception O briefing note, 2–5 on-site requirements, 278–85 guiding principles, 6 Ordinary method of slices, 100 risks and challenges, 6–7 Ostrom, E., 61 unique aspects of MoSSaiC, 5–6 outcomes. See project outcomes landslide risk and, 10–11 outputs. See project outputs management and government role, 4 outputs and outcomes as evidence of P effectiveness, 34, 35t, 390 Pack, R. T., 150 overview, 25–26 Pakistan, urban infrastructure projects in, 264–65 pilots, 35–41, 40t past landslides 4 0 0    I N D E X construction on former zones, 111, 113f immediate impact and project outputs, 353– drainage in areas of, 220–21, 222f 54, 354–55t failure to apply lessons learned from, 7 impediments to data collection, 350 local knowledge of, 185 key elements, 345–46 records of, 9 longer term, addressing landslide risk drivers Pelling, M., 21 over, 370–78 Periperi (southern Africa) studies of disasters, 9 anticipating future disaster risk scenarios, physically based landslide hazard assessment, 374–78, 377f 191–93, 202t connecting hazard reduction and piezometers, 380, 381f insurance, 371–74, 372–73t, 372f, piped water. See publicly supplied piped water 376t planned works, implementation of. See disaster risk reduction and climate implementation of planned works proofing, 370, 371t, 373 point sources, 181, 182, 185t, 186, 390 medium-term performance, 354–69, 355t policies cracks in houses, 358–60, 361f development of new landslide risk reduction drain performance, 362, 362f policies, 367–69, 368–69f economic appraisal, 364–67 regional policies, 84 environmental health benefits, 362–64, safeguard policies, 45, 46t, 64–65, 391 363f, 363t in tendering process, 277, 277f, 277t good landslide risk reduction practices, shift from ex post to ex ante policies, 14–17 367–69 policy entrepreneur role, 61, 62t policy makers, observed slope stability, 355–57, 356f, 356t and ex ante policies, 14 project value for money, 365, 365t and MoSSaiC projects, 368 rainfall and slope stability information, in MoSSaiC team reporting structure, 75f 357–58, 358f, 359t, 360f key role of, xxix surface and subsurface water, 360–62, 361f pore water pressure, 99-100, 105, 117, 120-23 piezometers, 380, 381f analysis of, 198 risks and challenges, 349–50 postconstruction bioengineering. See technical and physical effectiveness, 348 bioengineering top-down evaluation, 349–50 postfailure slope stability, 92, 93f value for money 364-66 poverty indicators, 155–56, 156t who does what, 379 Prater, C. S., 61 project inception, xxv, xxix, 55–79 preparatory factors. See landslide hazards briefing note, 56–57 probabilistic approaches, 95, 134, 149 community-based approach, 56, 62–64 procrastination, 7, 313 defining project scale, 42, 42–43t procurement. See preparation of work packages guiding principles, 57 project evaluation, xxviii–xxix, 345–85 key elements, 55–56, 57t adapting the MoSSaiC blueprint to existing logframe, creation of, 45, 47t capacity, 350, 351 MoSSaiC core unit (MCU). See MoSSaiC adoption of good landslide risk reduction teams practices, 367 platform for behavioral change, 58 aims of evaluation, 346–47 quality of project management, 58, 64 briefing note, 346–49 relevance of project documents, 58 capacity-building, awareness, and behavioral risks and challenges, 57–58 change, 348–49 safeguard policies, 45, 46t, 64–65, 391 community-based aspects, 346 schedule for delivery, 58 cost-benefit analysis, 365–67, 381–83, 382f scope of project, 62 cost-effectiveness, 348 teams. See MoSSaiC teams crack monitors, 379–80, 380f project outcomes, 27f, 33, 34, 35t, 47t, 346, 350, data requirements for, 350–53, 352f 352-55, 365 390 community knowledge and information, project outputs, 35, 40, 45, 350, 353, 354, 355t 352–53, 353f project step template, 76–77t, 390 MoSSaiC program data, 350–52 psychological barriers to landslide mitigation designing evaluation process, 347–48, 347f measures, 6–7 development of new landslide risk reduction publicly supplied piped water, evaluation of,188, policies, 367–69, 368–69f evidence base, 356–57, 369t 189f community evidence, 367 government evidence, 367 Q finalizing project evaluation process, 369–70 qualitative landslide hazard assessment, 188–91, guiding principles, 349 190f CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    4 0 1 R seepage zones, 181, 181f rainfall seismic events, 89–91, 91f slope stability and, 101–2, 357–58 septic waste, 182, 226, 242 assessment of rainfall events, 102 Shakoor, A., 95 empirical rainfall threshold modeling. See shallow landsliding model (SHALSTAB), 150 rainfall threshold Sharma, R. H., 106 triggering landslide disasters and fatalities, shear box, 94t, 106f 107, 194, 195, 199 9–10, 10–11f, 23, 83, 87–91, 120, 167– shear strength, 99-100, 114, 120, 391 68 shear surface. See slip surface rainfall threshold, 95, 98–99, 120, 390 show homes, 321–23, 322f, 322t rainwater harvesting, 244–47, 245–46f site supervision, 278–79, 278–79f, 291 Random Hacks of Kindness event (Washington, situational factors D.C.), 115 as barriers to landslide mitigation measures, rational method, 223, 224, 225t, 227, 228, 390 6–7 Rayner, S., 30 as determinants of vulnerability, 12 records of disasters, 9 slip surface, 99 regression methods, 96 slope angle, 103–4, 104f, 144t, 181 reporting lines, 74, 75f, 390 slope drainage. See drainage design and good resilience of structures, 153, 153f, 390 practice resistance envelope method, 116–17, 117f, 198, 390 slope hydrology, 88–89, 107–8 resolution of maps, 21, 67, 132, 149, 169, 390 slope instability classification, 87t resource gap, 371. 374, 376f slope stability retaining walls, 117–18, 118f, 122–23, 122f calculations, 100, 100f retrofitting, 244f, 247, 249, 390 CHASM. See CHASM (Combined Hydrology Richards, I. G., 294 and Slope Stability Model) risk, definition of, 11–14, 390 community-based mapping, 178–88. See also risk drivers. See landslide risk drivers community-based mapping risk management. See disaster risk management continuum and discrete element models, 101 (DRM) direct landslide mapping, 97–98 roof guttering, 242, 244, 244f, 282, 283f GIS-based landslide susceptibility mapping, root reinforcement equation, 122 95–96, 97f, 132, 134, 146–49 loading, 111–12, 112f rotational slides, 27, 84t, 85, 87, 87f, 87t, 90f, 91, 92, material types and properties, 104–7 108f, 100, 108, 137t, 158t, 190t, 204t hydrological properties, 105–7, 106f geotechnical properties, 99-101, 105. 117, S 120 safeguards, 45, 46t, 64-5, 73, 74, 136, 205, 215, 231, soil formation, 104, 105f 243t, 273t, 277, 300, 391 weathering and strength, 104–5, 106f St. Lucia medium-term performance, 355–57 drain construction method in, 240–41, 240– models, 134, 194–98, 195t 41f observed slope stability, 355–57, 356f, 356t economic losses from disasters in, 40 over time, 91–92, 92t hurricane damage in, 18–19, 18–19f, 40, 41f overview of assessment methods, 93–95, 94t hurricane-resistant home improvement physically based modeling, 99–101 program, 373, 375f postfailure, 92, 93f impacts of community-based risk reduction processes and their assessment, 93–101, 94t program in, 34, 35t project evaluation, 357–58 progressive slides in, 92f rainfall and, 101–2 rotational slides in, 90f empirical rainfall threshold modeling, translational slides in, 90f 98–99 “Samaritan’s dilemma,” 7, 61, 61t slope angle and, 103–4, 104f, 144t, 181 Samoa, economic losses in disasters in, 40 slope hydrology and drainage, 100–101, 107–8, San Salvador and coping with disasters, 29–30 107–8f scale of maps and plans, 391. See also community- urban slope drainage, 108 based mapping variables, 101–12 science-based landslide risk assessment, xxi, 4f, vegetation and, 108–11, 110f, 110t, 114–15 20–21, 26–29, 26t, 27f slums. See urbanization anthropogenic contributors to risk, 27–28, 28f small island developing states (SIDS), 8, 36, 40 landslide hazard, 112–18 social funds, role of, 21–23, 22f in landslide risk management, 20, 83, 84t socioeconomic vulnerability, 12, 151–52, 155–56, local risk drivers, 28 156t mapping for. See community-based mapping soil parameters. See also cohesion; angle of scientific and professional publications, 328–29 internal friction. 4 02    I N D E X Mohr-Coulomb equation for soil shear in model formulation, 200–201 strength, 114, 120 in physically based landslide hazard slope stability, 104, 105f assessment, 199–200 uncertainty in, 199–200, 200f in soil parameters, 199–200, 200f Sotir, R. B., 294 risk perception and, 313–14 Southeast Asia, rainfall-triggered landslide risk United Nations in, 9 capacity assessment methodologies of UNDP, Spector, S., 42 60 squatter housing, 391 on culture and community interests as Sri Lanka, urban infrastructure projects in, elements of project success, 172 264–65 disaster response organizational framework, Stability Index Mapping (SINMAP) model, 150 16f stakeholders, 44, 44t, 308, 312–14, 391. See Economic and Social Council’s definition of also communication; community gender mainstreaming, 173 engagement “Global Assessment Report on Disaster Risk statistical methods, 149–50 Reduction,” 80 strategic incrementalism, 368-69, 369f, 391 Human Development Index (HDI), 155 supervision. See site supervision International Strategy for Disaster Reduction, surface and subsurface water, 29, 89f, 360–62. See 23 also drainage design and good practice; risk assessment recommendations from, gray water management 20–21 estimation of surface water discharge, 223–26 UNICEF on behavioral change process in susceptibility, 95, 96t, 140–51, 142t Community-based Disaster Risk defined, 389 Reduction, 309 GIS-based landslide susceptibility mapping, on vulnerability of Eastern Caribbean, 36, 40 95–96, 97f, 98f, 132, 134, 146–49 University of Wollongong, Australia, example of hazard assessment methods, 140–51, 142t field reconnaissance and hazard ranking sustainability of MoSSaiC projects, xxii–xxiii, 64 methods, 145–46 Svekla, W., 29 urbanization, 23–25, 24f, 374 slope drainage and, 108, 109f T vegetation and slope management, 294–96, Tarboton, D. G., 150 296f Task teams. See advocacy task team; U.S. Federal Highway Administration, example of communications task team; community field reconnaissance and hazard ranking liaison task team; community task teams; methods, 146 government task teams; landslide assessment Useem, M., 304 and engineering task team; user groups, 75–76, 75f, 333–34, 334f mapping team; technical support task team technical support task team, 69, 69f, 140 V Tegucigalpa, Honduras, debris flow hazard in, Varnes, D. J., 85, 91 150–51, 150f value for money, in projects. See project evaluation temporal vulnerability, 12 vegetation threshold modeling, 98–99, 99f restricting alignment of drains, 220, 221f tolerable risk, 391 slope stability and, 108–11, 110–11f, 110t, 114–15, top-down approach, 25 144t, 293–94, 294f balancing with bottom-up approach, 61–62 urban slope management and, 294–96, 296f negative aspects of, 17 Venture Philanthropy Partners, 60 topography Victoria, Lorna P., 164 alignment of drains in complex topography, vulnerability 220, 221f of community to landslides, 151–56, 391. convergence zones, 179-80f See also communities at risk, mapping features, 169, 179, 179–80f prioritizing of slope reconnaissance form, 144t defined, 12, 83, 391 translational slides, 27, 84t, 85–86, 87f, 87t, 90f. drivers of landslide risk, 22 100, 132, 137t, 158t, 190t, 204t unauthorized housing, 24, 25t triggering events, 135t, 391. See also rainfall Twigg, J., 21, 366 W Wamsler, C., 16, 212 U weathering features, 104–5, 106f, 179–80, 180f, 391 “unacceptable risk,” 391. See also “acceptable risk” Wharton School of the University of unauthorized housing. See housing Pennsylvania, 18 uncertainty wide-area landslide hazard mapping, 21, 167 CO M M U N I T Y- B A S E D L A N D S L I D E R I S K R E D U C T I O N    4 0 3 Wilkinson, P. L., 114, 120, 294 Making Services Work for Poor People, 344 women. See gender relations natural disaster projects, 17, 17t work packages. See preparation of work packages Safeguard Policies, 45 World Bank World Development Report’s overview of assessment of economic impact of natural MoSSaiC, 25–26 disasters, 36 on communication campaigns, 317 Y on housing tenure in low-income countries, 24 Yunus, M., xxix 4 0 4    I N D E X ECO-AUDIT Environmental Benefits Statement The World Bank is committed to preserving endangered forests and natural resources. 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