78723 Issue #12 December 2012 Projecthighlights Destruction of a house caused by a rainfall-triggered landslide in an urban community - Castries, Saint Lucia. Management of Slope Stability in Communities (MoSSaiC) in Saint Lucia The Challenge: affected by heavy rains and hurricanes. Even “everyday� low magnitude rainfall events can trigger devastating Reducing Landslide Risk landslides. For the city’s inhabitants, this has meant In many developing countries, landslide risk is frequent loss of property and livelihoods, and even increasing as unauthorized housing is built on already loss of lives. As with any disaster risk, this also means landslide prone hillslopes surrounding urban areas. that the island is constantly under threat of reversing This risk accumulation is driven by growing population, whatever economic progress and improvements to increasing urbanization, and poor and unplanned livelihoods it has made. Yet, by taking a community- housing settlements, which result in increased slope based approach to landslide risk management, Saint instability for the most vulnerable populations. In Lucia has shown that even extreme rainfall events, addition, the combination of steep topography of such as Hurricane Tomas in October 2010, can be volcanic islands in the Eastern Caribbean and the weathered by urban hillside communities. climate patterns of heavy rains and frequent cyclonic Saint Lucia’s success in addressing landslide haz- activity, are also natural conditions contributing to the ards in urban communities is a result of the innova- high level of landslide risks. tive and solution-oriented engagement of community members, landslide researchers, and government prac- The Project: titioners and policy-makers. The Management of Slope Community-Based Risk Reduction Stability in Communities (MoSSaiC) approach was es- tablished by researchers from the University of Bristol The Caribbean island of Saint Lucia is a success story committed to providing a community-based and scien- in the long-running efforts to mitigate disaster risk tific approach for delivering landslide hazard reduction since the government began introducing low-cost measures on the ground. Following a successful pilot community-based interventions for vulnerable hillside study in 2004, the government of Saint Lucia funded communities. Castries, the capital of Saint Lucia, is the MoSSaiC projects in five vulnerable communities in most populated city and surrounded by mountainous which the community members became the lead project topography and is inhabited by populations commonly managers to reduce their landslide risk. www.worldbank.org/lcrdrm www.gfdrr.org Projecthighlights Research, development, and implementation continued ground, and an evidence base demonstrating that such an with the support of government agencies, international investment both pays and works. development partners, and in close collaboration with the MoSSaiC is science-based: World Bank’s Disaster Risk Management (DRM) Team. Under ■■ Localized physical causes (often poor drainage) the World Bank-sponsored Second
 Disaster Management of landslide hazard are identified. Project, the government and project committee identified ■■ Appropriate mitigation measures are designed six more vulnerable communities to implement the MoSSaiC approach. Each of the communities received technical, to address these causes. ■■ Scientific methods are used to justify solutions. financial and project management support to install drainage systems, rainwater harvesting techniques and catchments to divert rainfall from saturating the soil and foundations to MoSSaiC is community-based: ■■ Community residents are engaged in identifying landslide homes that instigate landslides. MoSSaiC continues to work with the World Bank
 and risk causes and solutions. communities to develop a handbook and online resources to ■■ Contractors and workers from the community are make the
approach more widely available and useful to the employed in constructing drainage solutions. general population and related ministries. The Global Facility ■■ Government managers and practitioners form teams with for Disaster Reduction and Recovery (GFDRR) is financing the the necessary expertise to work with communities and production, publication and dissemination of these materials, deliver mitigation measures. which are expected in early 2013. ■■ The vision is shared and championed in communities and by governments. An Innovative Approach to Landslide MoSSaiC is evidence-based: Hazards ■■ Appropriate physical works are delivered to reduce Current policies for landslide risk reduction often focus on landslide hazard. vulnerability reduction without always investigating ways ■■ MoSSaiC design standards and trainings are used to to address the landslide hazard. The MoSSaiC approach maintain rigorous and effective quality. explicitly addresses landslide hazard reduction. It is based on the MoSSaiC vision that (i) disaster risk management pays, Communities Tackle the Causes (ii) engaging existing government expertise for risk reduction of Landslide Risk can build capacity, embed good practice and change policy, and (iii) ensuring community engagement from start to finish MoSSaiC is designed to address a very significant subset of can enable community ownership of solutions. The MoSSaiC landslide types: rotational and translational slides in soils approach aims to lay sustainable foundations for community- that are principally triggered by rainfall, but which are ex- based landslide risk reduction. These foundations are a acerbated by rapid urbanization. Often, the most socioeco- scientific base for reducing landslide hazard, a community- nomically vulnerable inhabit these landslide-prone slopes— based approach for delivery of mitigation measures on the thus increasing their exposure to landslide hazards and SCIENCE-BASIS COMMUNITY-BASIS Slope mapping of landslide hazard factors: Assessment of each landslide hazard: • local slope geometry and surface drainage • type, likelihood, location & magnitude • soils and geology • dominant landslide causes • surface cover and loading Community: Slope mapping of exposure and vulnerability factors: Assessment of vulnerability to each landslide • leaders • local slope geometry and surface drainage hazard: • organizations • soils and geology • potential losses due to each landslide • residents • surface cover and loading • behavioural change • contractors Government: Landslide risk for each community (hazard, exposure and vulnerability) Landslide risk • management management: • experts • prioritise communities • technicians • design landslide hazard reduction interventions • practitioners EVIDENCE-BASIS Implement hazard reduction measures: Evaluate inputs and outcomes: • community engagement • technical/physical effectiveness • construction • cost-effectiveness • maintenance • behavioural change The MoSSaiC Architecture: A holistic structure combining the three core scientific, community, and evidence components. 2 Projecthighlights Typical urban hillside community in Saint Lucia. Discussing the surface water and slope stability issues and potential drainage solutions at a community meeting. sometimes increasing the hazard itself. MoSSaiC focuses on totaling over 50 centimeters in just 24 hours. However, none the most economically, socially, and physically vulnerable of of the vulnerable hillside communities that implemented these urban hillside communities. MoSSaiC interventions experienced any landslides at all. Before During the initial project steps, community residents and the intervention, those same community slopes had frequently government technical teams create detailed maps of slope fea- shown signs of instability, even during much lower magnitude tures such as previous landslides and altered slope geometry rainfall events of less than 10 centimeters in 24 hours. (cut and fill), loading (buildings), drainage, and vegetation. En- gineering judgment and scientific tools are used to interpret Cost-benefit – ‘it pays’ the effect of such features on slope stability and confirm local landslide causes. Typically, the dominant instability mecha- Governments and donors agree that disaster mitigation is a nism in these densely constructed communities is infiltration good idea, but the question always remains ‘does it pay?’ This of rainfall and household water into slope material. Based on answer requires evidence of the likely returns on investments that information, drains are designed to intercept overland made in the communities. A particular challenge in assess- flow of rainfall and capture household water (roof water and ing the direct benefits of disaster risk management lies in the grey water), thus reducing landslide hazard. Finally, these pub- fact that such benefits occur in the future as avoided costs, lic works are bid out to local contractors in the community. rather than as a continual flow of positive benefits. It is there- MoSSaiC’s activities engage community participation in fore vital that economic appraisal of landslide risk reduction a holistic approach in every step of the project including plan- projects be carried out, not only as a means of ensuring effec- ning, executing, and maintaining surface water management tiveness, but also in order to build a case for low-cost, high- on high-risk slopes. Contractors and workers are from the benefit landslide risk mitigation. communities and trained on MoSSaiC design standards. They To start to build such an evidence base, a pilot cost-benefit gain short-term employment, capacity building and work ex- analysis was undertaken for one of the MoSSaiC communities perience in effective slope drainage construction practices. in St Lucia. Slope stability modeling showed that prior to the As a result, the vision for proactive landslide risk manage- intervention a 1 in 5 year rainfall event would be likely to trig- ment is shared, championed, and owned by the communities ger multiple small landslides. Rainfall running off roofs and themselves, not only by the government or implementing grey water from kitchens and bathrooms significantly contrib- agency. At the same time, the community becomes a class- uted to this problem. After constructing new drains and captur- room for the government teams to develop their expertise, and establish good technical and managerial practices with Natural disasters such as respect to landslide hazard. Hurricane Tomas impose large costs The Results: on Saint Lucia’s economy by seriously Stable Hillslopes – ‘it works’ impacting tourism and agriculture, According to Françoise Clottes, World Bank Country Director for the Caribbean, “natural disasters such as Hurricane Tomas with particularly severe effects on the impose large costs on Saint Lucia’s economy by seriously most vulnerable communities and impacting tourism and agriculture, with particularly severe effects on the most vulnerable communities and households.� households. For Saint Lucia, the most damaging feature of Hurricane Tomas —Françoise Clottes, World Bank Country Director for the was the torrential and sustained rainfall that it brought— Caribbean. 3 Projecthighlights [During Hurricane Tomas] the water was as high and gushing as I never seen before. The timing of the drains being installed was so right, just before the storm, as no landslides occurred as they did before. —Eldrena St. Luce, Community Leader, Morne du Don – Castries, Saint Lucia. Example of drain to collect and redirect surface water runoff to prevent soil saturation and landslides. ing household water, less water was able to infiltrate the slope; Learning by Doing 35 percent of rainfall was intercepted by roofs and conveyed to new drains, while approximately 50 percent of the remain- The transfer of science into practice is both complex and moves ing rainfall was estimated to be removed from the slope from in both directions. In consequence, MoSSaiC’s community- surface water runoff being intercepted by drains. This reduced based approach is that of “learning by doing� for all involved. the modeled probability of landslides by an order of magnitude In addition to mitigating landslide risk, a core advantage for (from 1 in 5 years to 1 in 50 years). The expected reduction in all participants includes the rapid and highly focused educa- damage to houses of different construction types was calcu- tion and training. Community residents and government teams lated from predicted magnitude and location of landslides be- alike broaden their knowledge and skill-base with enthusiasm fore and after the intervention. This study showed that directly because they can see the results that directly affect security. addressing the physical causes of the landslide hazards in such Familiarity with the science of hazard reduction is an integral communities can have a benefit-cost ratio of 2.7:1 – a low-cost, part of the learning process; so much so that community mem- high impact approach to landslide risk reduction. bers are subsequently able to participate in technical training and provide instruction to government staff. As communities and governments adopt the methodology Complete Community Engagement and MoSSaiC blueprint and by making adaptations that are rel- The MoSSaiC initiative demonstrates that community engage- evant to local conditions (political, social, and physical), coun- ment and active participation - from project initiation through to try ownership will follow. For that to happen, governments and post-project workshops – is effective in reducing landslide risk donors will need to be policy entrepreneurs—identifying what and building community capacities and awareness. Community works and what pays when it comes to urban landslide risk re- members and local contractors can apply their experience and duction, and making “smart� links between science, social sci- local knowledge with MoSSaiC design standards to integrate ence, and behavioral sciences. landslide hazard mapping and drainage design. In addition to re- While a community-based methodology may be suitable ducing landslide hazard, many residents learn good construction in terms of effective landslide hazard mitigation, there is every practices through their involvement in drainage construction and possibility of continued accumulation of landslide risk, driven on-site guidance from engineers and experienced local contrac- by the trend of increasing urbanization. The poorest are mov- tors. Communities also manage the procurement of materials, ing to the least expensive land surrounding urban areas—often lead community meetings, and post-project maintenance. This the most landslide-prone slopes. This trend, coupled with a level of community participation is a direct result of their initial substantial, unregulated housing stock, presents a major chal- engagement in the mapping process and involvement throughout lenge in many countries, including small island developing the project. Finally, because governments have adapted and en- states such as Saint Lucia. The MoSSaiC approach to reduce couraged the community-based approach to landslide mitigation, urban landslide hazards has the potential to decrease landslide donors continue to support the scaling up of MoSSaiC throughout risk accumulation, but it now requires a concerted program of the islands of the Caribbean. dissemination and adoption of its methodology. Disclaimer: The findings, interpretations, and conclusions expressed herein are those of the author(s) and do not necessarily reflect the views of the Executive Directors of the International Bank for Reconstruction and Development, The World Bank 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 informa- tion 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.