55027 Water Working Notes Water Working Notes Note No. 25, June 2010 Water and Climate Change: impaCts on groundWater resourCes and adaptation options Craig Clifton Rick Evans Susan Hayes Rafik Hirji Gabrielle Puz Carolina Pizarro Water Working notes are published by the Water Sector Board of the Sustainable Development Network of the World Bank Group. Working Notes are lightly edited documents intended to elicit discussion on topical issues in the water sector. Comments should be e-mailed to the authors. Table of ConTenTs Acknowledgements ................................................................................................................................................................................................. vi Abbreviations and Acronyms .........................................................................................................................................................................vii Executive Summary.................................................................................................................................................................................................. ix 1. Introduction............................................................................................................................................................................................................ 13 1.1 Groundwater in World Bank regions ................................................................................................................................13 1.2 Climate change .............................................................................................................................................................................14 1.3 About this report ..........................................................................................................................................................................15 2. Climate Change, Hydrological Variability and Groundwater .......................................................................................... 17 2.1 Fundamental concepts ............................................................................................................................................................17 2.1.1 Groundwater and the hydrologic cycle .......................................................................................................17 2.1.2 Climate change and hydrologic variability.................................................................................................18 2.2 Impacts of climate change on groundwater ..............................................................................................................18 2.2.1 Recharge ..........................................................................................................................................................................18 2.2.2 Discharge.........................................................................................................................................................................22 2.2.3 Groundwater storage...............................................................................................................................................23 2.2.4 Water quality .................................................................................................................................................................23 2.3 Impacts of non-climatic factors ..........................................................................................................................................24 2.4 Implications for groundwater dependent systems and sectors.....................................................................25 2.4.1 Rural and urban communities............................................................................................................................25 2.4.2 Agriculture ......................................................................................................................................................................25 2.4.3 Ecosystems .....................................................................................................................................................................25 2.5 Uncertainties and knowledge gaps .................................................................................................................................26 2.6 Groundwater vulnerability to climate change at a World Bank regional scale......................................26 3. Adaptation to Climate Change ................................................................................................................................................................ 29 3.1 Introduction.....................................................................................................................................................................................29 3.2 Adaptation options for risks to groundwater dependent systems from climate change and hydrological variability ....................................................................................................................................................31 3.2.1 Building adaptive capacity for groundwater management ............................................................32 3.2.2 Managing groundwater recharge ...................................................................................................................32 3.2.3 Protecting groundwater quality........................................................................................................................32 3.2.4 Managing groundwater storages ....................................................................................................................36 3.2.5 Managing demand for groundwater .............................................................................................................36 3.2.6 Management of groundwater discharge ....................................................................................................36 3.3 Managing for increased groundwater recharge.......................................................................................................38 iii Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options 3.4 Examples of adaptation to climate change and hydrological variability from developing countries.................................................................................................................................................................39 3.4.1 Managed aquifer recharge ...................................................................................................................................39 3.4.2 Groundwater protection: adaptations and challenges for a low atoll ......................................42 3.5 Discussion .........................................................................................................................................................................................43 3.5.1 Avoiding adaptation decision errors ..............................................................................................................43 3.5.2 Evaluation of adaptation options .....................................................................................................................44 3.5.3 Barriers to introduction of adaptations.........................................................................................................44 3.5.4 Economic considerations ......................................................................................................................................44 4. Examples of Adaptation Measures....................................................................................................................................................... 47 4.1 Introduction.....................................................................................................................................................................................47 4.2 Case study comparison ............................................................................................................................................................47 4.2.1 Establishing the context ........................................................................................................................................47 4.2.2 Identifying and analyzing risk .............................................................................................................................49 4.2.3 Evaluating and treating risks ...............................................................................................................................50 4.2.4 Stakeholder engagement .....................................................................................................................................50 4.2.5 Monitoring and review ...........................................................................................................................................51 4.2.6 Observed success factors and barriers for adaptation ........................................................................52 4.3 UK case study summary ...........................................................................................................................................................53 4.4 USA case study summary........................................................................................................................................................55 4.5 Australian case study summaries .......................................................................................................................................57 4.5.1 Management of the Gnangara Mound, Western Australia ..............................................................57 4.5.2 Hawkesdale Groundwater Management Area, Victoria .....................................................................59 5. Conclusion ............................................................................................................................................................................................................... 61 6. Recommendations ............................................................................................................................................................................................ 63 7. Glossary of Terms................................................................................................................................................................................................ 65 8. References ................................................................................................................................................................................................................ 73 Figures Figure 1.1: Reported Countries with Groundwater Depletion...........................................................................................14 Figure 2.1: The Hydrologic Cycle...........................................................................................................................................................17 Figure 2.2: Global Estimates of Climate Change Impact on Groundwater Recharge..........................................20 Figure 2.3: Summary of Climate Change Impacts on Recharge under Different Climatic Conditions.....21 Figure 2.4: Simulated Change in Recharge per Unit Change in Rainfall under a Double-CO2 climate change Scenario in Western Australia (Green et al., 1997) ...............................................................21 Figure 2.5: Change in Rainfall Versus Change in Recharge for Murray Darling Basin, Australia.....................22 Figure 2.6: Schematic Representing the Loss of Fresh Groundwater Resources Due to Saltwater Intrusion in Coastal Aquifers .....................................................................................................................24 iv Table of Contents Figure 3.1: Coping Range and Adaptation to Human-Induced Climate Change (redrawn from Willows and Connell, 2003) ..................................................................................................................29 Figure 3.2: Conceptualization of Adaptation of a Groundwater Dependent System to Climate Change and Variability (redrawn from Smit et al., 2000) .............................................................30 Figure 3.3: Classification of Adaptation Options (redrawn from Burton, 1996) .......................................................31 Figure 3.4: Groundwater Adaptation Options, Based on Groundwater Processes and Location in the Landscape .....................................................................................................................................................32 Figure 3.5: Examples of Managed Aquifer Recharge (MAR) Approaches....................................................................41 Figure 3.6: Cross section of Sand Dam Structure (from Foster and Tuinhof, 2004) ...............................................42 Tables Table 1.1: Groundwater use in World Bank Regions .................................................................................................................14 Table 2.1: Projected Impact of Global Warming for Primary Climate and Hydrologic Indicators.................19 Table 2.2: Preliminary Assessment of Vulnerability of Groundwater in World Bank Regions to Climate Change.......................................................................................................................................................................27 Table 3.1: Adaptation Options: Building Adaptive Capacity................................................................................................33 Table 3.2: Adaptation Options: Managing Groundwater Recharge................................................................................34 Table 3.3: Adaptation Options: Protecting Groundwater Quality ....................................................................................35 Table 3.4: Adaptation Options: Managing Groundwater Storages .................................................................................36 Table 3.5: Adaptation Options: Managing Demand for Ground.......................................................................................37 Table 3.6: Adaptation Options: Managing Groundwater Discharge ..............................................................................38 Table 3.7: Adaptation Options: Managing Increased Groundwater Recharge ........................................................39 Table 4.1: Context for the Four Adaptation Case Studies ......................................................................................................48 Table 4.2: Case Study Overview ­ Identifying and Analyzing Risk...................................................................................49 Table 4.3: Case Study Overview ­ Evaluating and Treating Risk........................................................................................51 v aCknowleDgemenTs The World Bank is grateful to the Government of the Neth- es Assessment Centre (IGRAC), particularly Dr. Neno Kukuric, erlands for financing the production of this report. Peter Litire, Slavek Vasak and Jac van der Gun; Stephen Fos- ter (IAH, GW-MATE); Peter Dillon (CSIRO Australia, Chairper- This abbreviated report was drawn by Rafik Hirji (Task Team son of the IAH Commission on MAR); Peta Döll (University Leader) with the support of Gabrielle Puz and Carolina Piz- of Frankfurt); Ricky Murray (South Africa); Matthew Rodell zaro of ETWWA, World Bank, from the larger report drafted (NASA); Tom McMahon (University of Melbourne, Australia) by Craig Clifton, Rick Evans and Susan Hayes of SKM, Austra- and Professor Yongxin Xu (University of the Western Cape, lia as part of a contract for the World Bank ESW on Climate South Africa; UNESCO Chair in Hydrogeology). Change and Water. Case studies were compiled by Ian Holman and Keith Weatherhead (Cranfield University, UK), The larger report by SKM report was also reviewed by the Steve Sagstad (Brown and Caldwell, USA) and Greg Hoxley following World Bank staff: Maher Abu-Taleb, Vahid Alavian, (SKM, Australia). Tracy Hart, Gabrielle Louise Puz, Douglas Olson, Halla Qad- dumi, and Rafik Hirji. The authors wish to thank the following for their helpful reviews and input: Phil Commander (Department of Water, Approving Manager: Julia Bucknall, Sector Manager, ETWWA Western Australia); the International Groundwater Resourc- DisClaimer This volume is a product of the staff of the International permission may be a violation of applicable law. The Bank for Reconstruction and Development/The World International Bank for Reconstruction and Develop- Bank. The findings, interpretations, and conclusions ment/The World Bank encourages dissemination of its expressed in this paper do not necessarily reflect the work and will normally grant permission to reproduce views of the Executive Directors of The World Bank or portions of the work promptly. the governments they represent. 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Copying pubrights@worldbank.org. and/or transmitting portions or all of this work without vi abbreviaTions anD aCronyms AAA Advisory and analytic activities GMA Groundwater Management Area ACRA Country Adaptation to Climate Risk Assess- GNI Gross National Income ment GPG Global public good ADWR Arizona Department of Water Resources GRAPHIC Groundwater resource assessment under the AFR Africa Region pressures of humanity and climate changes AMCOW African Minister's Council on Water GSS Gnangara Sustainability Strategy AOGCM Atmospheric-Ocean General Circulation Model GWSP Global Water System Project AS/NZS Australian Standards/New Zealand Standards HadCM3 Hadley Centre Coupled Model, Version 3 ASR Aquifer Storage and Recovery IAH International Association of Hydrogeologists ASTR Aquifer Storage, Treatment and Recovery IBRD International Bank for Reconstruction and De- AWS Assured Water Supply velopment CAP Central Arizona Project IDA International Development Association CAS Country Assistance Strategy IFC International Finance Corporation CC Climate Change IGRAC International Groundwater Resources Assess- CDM Clean Development Mechanism ment Centre CEIF Clean Energy for Development Investment IHP International Hydrological Programme Framework IOD Indian Ocean Dipole CF Carbon Finance IPCC Intergovernmental Panel on Climate Change COP Conference of the Parties IPO Interdecadal Pacific Oscillation CO2 Carbon dioxide IWSS Integrated Water Supply System CPIA Country Policy and Institutional Assessment km Kilometer CSIRO Commonwealth Scientific and Industrial Re- LCR Latin America and the Caribbean search Organization (Australia) MAR Managed Aquifer Recharge DEC Development Economics Department MCA Multi-Criteria Analysis DPL Development policy lending MCE Multiple Criteria Evaluation EAP East Asia and the Pacific MDG Millennium Development Goals ECA Europe and Central Asia MIGA Multilateral Investment Guarantee Agency ECHAM4 Fourth-generation atmospheric general cir- ML Mega liter culation model developed at the Max Planck MNA Middle East and North Africa Institute for Meteorology (MPI) MOSES Met Office Surface Exchange Scheme ENSO El Nińo-Southern Oscillation NAO North Atlantic Oscillation ESMAP Energy Sector Management Assistance Pro- NAPA National Adaptation Programme of Action gram NVB Newer Volcanic Basalt 4AR Fourth Assessment Report (IPCC) ODA Official Development Assistance FAR First Assessment Report (IPCC) PCL Port Campbell Limestone GCM General Circulation Model PCMDI Program for Climate Model Diagnostics and GDE Groundwater Dependent Ecosystem Intercomparison GDP Gross domestic product PPIAF Public-Private Infrastructure Advisory Facility GEF Global Environment Facility ppm parts per million GHG Greenhouse gases PPP Public-Private Partnership GL Giga liter PRSP Poverty Reduction Strategy Paper vii Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options PSDI Palmer Drought Severity Index TAR Third Assessment Report (IPCC) RCM Regional Climate Model UK United Kingdom SADC South African Development Community UNDP United Nations Development Programme SAR Second Assessment Report (IPCC) UNEP United Nations Environment Programme SAR South Asia Region UNESCO United Nations Educational, Scientific and Cul- SCCF Special Climate Change Fund tural Organization SD Statistical Downscaling UNFCCC United Nations Framework Convention on Cli- SEA Strategic Environmental Assessment mate Change SKM Sinclair Knight Merz USA United States of America SRES Special Report on Emissions Scenarios WA Western Australia SSA Sub-Saharan Africa WBG World Bank Group STP Sewage treatment plant WGHM WaterGAP Global Hydrology Model SWAp Sectorwide approach WDR World Development Report TA Technical assistance viii exeCuTive summary Adaptation to climate impacts on groundwater re- They provide a significant opportunity to store excess water sources in developed and developing countries has during high rainfall periods, to reduce evaporative losses not received adequate attention. This reflects the often and to protect water quality. However these opportunities poorly understood impacts of climate change, the hidden have received little attention, in part because groundwater nature of groundwater and the general neglect of ground- is often poorly understood and managed. water management. Many developing countries are highly reliant on groundwater. Given expectations of reduced supply in many regions and growing demand, pressure on reducing vulnerability through groundwater resources is set to escalate. This is a crucial adaptation problem and demands urgent action. Groundwater plays a critical role in adapting to hy- This report addresses the impacts of climate change on drologic variability and climate change. Groundwater groundwater and adaptation options. It is an abbreviated options for enhancing the reliability of water supply for do- version of a larger report prepared by Sinclair Knight Merz mestic, industrial, livestock watering and irrigation include (SKM)1 for the World Bank as a special paper for the Water (but are not exclusive to): Anchor flagship Climate Change and Water. The larger re- port will also form one of several thematic papers for the ˇ Integrating the management of surface water and new global groundwater governance project that is under groundwater resources ­ including conjunctive use of preparation by the World Bank. both groundwater and surface water to meet water demand. Integrated management aims to ensure that the use of one water resource does not adversely im- The importance of groundwater in a pact on the other. It involves making decisions based changing climate on impacts for the whole hydrologic cycle. ˇ Managing aquifer recharge (MAR) ­ including build- The Earth's climate is projected to become warmer ing infrastructure and/or modifying the landscape to and more variable. Increased global temperatures are intentionally enhance groundwater recharge. MAR is projected to affect the hydrologic cycle, leading to changes among the most promising adaptation opportunities in precipitation patterns and increases in the intensity and for developing countries. It has several potential ben- frequency of extreme events; reduced snow cover and efits, including storing water for future use, stabilizing widespread melting of ice; rising sea levels; and changes in or recovering groundwater levels in over-exploited soil moisture, runoff and groundwater recharge. Increased evaporation and the risk of flooding and drought could adversely affect security of water supply, particularly surface 1 Sinclair Knight Merz (SKM). 2009. Adaptation options for climate water. Due to these pressures, as well as global population change impacts on groundwater resources. Victoria. Australia. The growth, demand for groundwater is likely to increase. larger report: (a) characterizes the impact of current and projected hydrologic variability and Climate Change on groundwater, (b) develops a Methodology for Assessing Vulnerability and Risk in Compared to surface water, groundwater is likely to be Groundwater Dependent Water Systems to Hydrological Variability much more compatible with a variable and changing and Climate Change and (c) presents four developed nation case studies from Australia, Europe, and the United States. The methodol- climate. Relative to surface water, aquifers have the capac- ogy for assessing vulnerability and risk developed under the larger ity to store large volumes of water and are naturally buff- report was omitted in the abbreviated report in order to avoid ered against seasonal changes in temperature and rainfall. confusion with the methodology presented in the flagship report. ix Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options aquifers, reducing evaporative losses, managing saline tion may warrant introducing fees/charges for ground- intrusion or land subsidence, and enabling reuse of water use, so that an appropriate level of cost recovery waste or storm water. is met. An economic assessment of adaptation options ˇ Land use change ­ changing land use may provide an op- should factor any initial and ongoing costs, and means for portunity to enhance recharge, to protect groundwater financing these. It must also take into account the local eco- quality and to reduce groundwater losses from evapo- nomic environment, which can vary significantly between transpiration. Changes in land use should not result in and within nations. adverse impacts to other parts of the environment. Groundwater is also vulnerable to climate change and adaptation can start now hydrological variability. Potential climate risks for ground- water include reduced groundwater recharge, sea water in- In many cases, adaptations to reduce the vulnerability trusion to coastal aquifers, contraction of freshwater lenses of groundwater dependent systems climatic pres- on small islands, and increased demand. Groundwater can sures are the same as those required to address non- also be affected by non-climatic drivers, such as population climatic pressures, such as over-allocation or overuse growth, food demand and land use change. Active consid- of groundwater. Such `no regrets' adaptations can be eration of both climatic and non-climatic risks in groundwa- implemented immediately in areas where water resources ter management is vital. are already stressed, regardless of concerns about the un- certainty of climate change projections and assessments of impact on groundwater and surface water resources. effective decision making Successful examples of groundwater adaptation to Effective, long term adaptation to climate change and climate change and hydrologic variability exist in both hydrologic variability requires measures which protect developed and developing nations. A list of available ad- or enhance groundwater recharge and manage water aptation options is included in this report. Adaptation case demand. Adaptation to climate change can't be separated studies from three developed nations (England, America from actions to improve management and governance and Australia) are also provided. of water reserves (e.g. education and training, information resources, research and development, governance and in- stitutions). recommendations Adaptation needs to be informed by an understand- To improve the Bank and client country capacity for and ing of the local context, and of the dominant drivers uptake of groundwater adaptation, the following next steps (and their projected impact) on groundwater resources are recommended: in the future. Adaptations must be carefully assessed to ensure investment in responses to climate change and 1. Support adaptation case studies in developing na- hydrological variability is proportional to risk and that they tions ­ adaptation case studies from three developed do not inappropriately conflict with other social, economic, nations were reviewed in the current report. As part resource management or environmental objectives. Ad- of the global groundwater governance project and aptations should not add further pressures on the global the Bank's sector analysis on groundwater governance climate system by significantly increasing greenhouse gas project, a series of case studies and evaluations are emissions. recommended to be prepared for developing coun- tries. Possible case study countries could include: Peru, Adaptation options need to be economically viable. In India, Kenya, Mexico, Morocco, Tunisia, South Africa, some cases the cost and benefits of an adaptation op- Tanzania and Yemen. The following transboundary x Executive Summary aquifers might also be considered to be part of these ning for MAR should be coupled with demand case studies: management strategies. ˇ Capacity building in groundwater management ˇ the Nubian sandstone aquifer system ­ this aqui- and planning. This may include activities such fer is located in north-eastern Africa and spans the as groundwater resource assessments to bet- political boundaries of four countries: Chad, Egypt, ter understand the resource, establishing and Libya and Sudan; populating groundwater databases, increasing ˇ aquifers that span across the fourteen countries the level of hydrogeological expertise by estab- in the South African Development Community lishing or improving accessibility to groundwater (SADC). training institutions, a manual for groundwater management to outline minimum good practice These case studies would provide policy and operational standards etc. guidance (lessons and experiences) to water resource man- ˇ More integrated management of water resources. agers in similar settings on improving groundwater gover- This may include conjunctive water use and as- nance and conceptualizing and implementing adaptation sessing the impacts of existing or proposed infra- programs. As a minimum the case studies should focus on structure to identify any potential inefficiencies or examples of MAR, improved management of groundwater adverse impacts that may be treated to achieve storage, conjunctive use, planning and management of optimal use of water resources. groundwater and surface water and reform of water gover- nance. The case studies should cover a range of biophysical 3. Disseminate knowledge - Information from this re- and institutional settings and be representative of different port and developing country case studies should be kinds of experienced climate change or climate risk impact. disseminated to World Bank staff as part of the overall sector analysis on Climate Change and Water. 2. Promote groundwater management and develop- ment opportunities ­ identify and integrate oppor- 4. Collaborate with programs and partner agencies tunities to manage and develop groundwater in future with specialized knowledge--including: water sector programs to improve the reliability of water supply for multiple uses and protection of eco- ˇ Groundwater Resources Assessment under the systems. This may include supporting: Pressures of Humanity and Climate Change (GRAPHIC)--the GRAPHIC project is hosted by IHP ˇ Assessment of the suitability of MAR ­ to deter- UNESCO, IGRAC and GWSP and focuses on under- mine the potential viability for MAR. This assess- standing the impacts of climate change and other ment should identify areas of current water stress pressures for groundwater, globally; (i.e. need), water availability (e.g. excess wet sea- ˇ International Association of Hydrogeologists (IAH), son surface flows, treated waste water), potential and storage, and the likelihood that groundwater qual- ˇ International Groundwater Resource Assessment ity will be suitable for the required use/s. Any plan- Centre (IGRAC) xi 1. inTroDuCTion There is understandable concern about the potential 1.1 groundwater in world bank regions impacts of human-induced climate change on water re- sources. While at a global level rainfall should increase due Groundwater and soil moisture collectively account for over to increased evaporation, this change will be unevenly 98% of global fresh water resources, with more than two distributed and many regions are projected to receive billion people dependent on groundwater for their daily substantially less rain (IPCC, 2007). When combined with supply (Hiscock, 2005). Groundwater is a major source of increased temperatures, the retreat of glaciers, rising sea water for agriculture and to meet basic human needs in levels and increasing demand for fresh water from rapidly developing countries. growing populations, the pressure on water resources is set to escalate. While not the dominant source of water in any of the six World Bank regions, groundwater is the major source in sev- Concern about climate change and water resources has eral countries (Table 1.1). Groundwater is most intensively translated into an impressive array of studies of potential developed in the World Bank's Middle East ­ North Africa impacts and adaptations. However, in comparison to sur- and Latin America-Caribbean regions. face water resources, the level of attention paid to ground- water, particularly in developing countries, has been limited. The hidden nature of groundwater, its resilience in the face This reflects the hidden nature of groundwater, the general of short-term climatic variability and the difficulty in mea- neglect of its management, as well as uncertainties about suring it, have, among other factors, contributed to its poor the potential impacts of climate change. management and the growing stress on groundwater re- sources. In many countries, even developed countries with This report ­ Water and Climate Change: Impacts on robust surface water management arrangements, ground- groundwater resources and adaptation options--has been water use is unregulated and poorly planned and managed. prepared as a special paper for the World Bank flagship on Unsustainable management has resulted in the depletion Climate Change and Water. The flagship covers Climate of groundwater in both developed and developing nations Change and Water issues from a broad and multi-sectoral (Figure 1.1). Usage often exceeds average annual recharge. perspective. This report is an abbreviated version of a larger In some North African and Middle East nations, water use report prepared by SKM for the World Bank2. The larger re- exceeds recharge by a factor of three (IGRAC, 2004; http:// port will also form one of the thematic papers for the global igrac.nitg.tno.nl/ggis_map/start.html). groundwater governance project that is under preparation by FAO and the World Bank. Pressures on surface water resources are intensifying, due to growth in population, increased demand for food, pollution and (in some regions) climate change. As this occurs, these pressures are increasingly being referred to groundwater 2 The larger report: (a) characterizes the impact of current and and the need for improved management grows. projected hydrologic variability and Climate Change on ground- water, (b) develops a Methodology for Assessing Vulnerability and Risk in Groundwater Dependent Water Systems to Hydrological Groundwater also plays an important role in sustaining a Variability and Climate Change and (c) presents four developed wide range of terrestrial, aquatic and marine ecosystems. nation case studies from Australia, Europe, or the United States. For some ecosystems, there is a highly specialized depen- The methodology for assessing vulnerability and risk developed dency on groundwater; for example for habitat, water sup- under the larger report was omitted in the abbreviated report in order to avoid confusion with the methodology presented in the ply or survival during drought (e.g. Hatton and Evans, 1998; flagship report. Clifton and Evans, 2001). 13 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options table 1.1: groundwater use in World Bank regions Groundwater use as % of total water use Examples of countries where >50% of water Average % use across Maximum recorded is sourced from World Bank region region1 percentage of use groundwater East Asia and Pacific 19 79 Mongolia Europe and Central Asia 22 83 Georgia, Lithuania. Latin America and the Caribbean 32 96 Barbados, Bolivia, Jamaica. Middle East and North Africa 41 78 Iran, Libya, Tunisia. South Asia 26 35 - Africa 18 54 Botswana, Mauritania, Namibia. Source data: IGRAC 1 Where data available. Figure 1.1: reported Countries with groundwater depletion Source: IGRAC Global Groundwater Information System: http://igrac.nitg.tno.nl/ggis_map/start.html 1.2 Climate change climatic conditions, with impacts on hydrological cycles evident at some locations (IPCC, 2007). Global change sce- Atmospheric concentrations of carbon dioxide and other narios anticipate further large increases in greenhouse gas greenhouse gases are increasing. There is a growing body emissions over the course of this century, with consequenc- of evidence that this is already contributing to changes in es for climate including increased surface temperature, 14 Introduction changes in the amount and pattern of precipitation and in- This report also proposes the scope of subsequent phases creased potential evaporation. The nature of these changes which will be supported under the new global ground- is projected to vary across the globe. The critical threats to water governance project and will (a) identify, assess and groundwater (and dependent systems) from these changes begin to implement adaptation options for improving the is reduced availability of groundwater, due to reduced resilience of groundwater systems in selected developing groundwater recharge, increased demand or groundwater nations and (b) disseminate project outputs to World Bank contamination (Section 2.2). The implications for socio-eco- staff working in water supply, irrigation and water resources nomic and environmental conditions in vulnerable regions management. could be very serious. There is a `basic need to identify the sensitivity of groundwater to climate variability and change' The target audience is technical and non technical water (GRAPHIC, 2008). Adaptation is required to address the risks supply, irrigation, water resources and environmental spe- faced and improve the resilience of groundwater depen- cialists from the Bank, other institutions and client nations. dent communities and environments. This report is structured as follows: 1.3 about this report Section 1: Introduction ­ briefly summarizes the context, pur- pose and scope of the project This report is a special paper for the Water Anchor flagship Climate Change and Water. Its overall objective is to devel- Section 2: Climate change, hydrological variability and ground- op an analytical framework for improving the resilience of water ­ a review of the linkages between groundwater and groundwater dependent communities and environments climate, the impacts of climate change on groundwater in the face of threats from increasing demand, unsustain- resources, and implications for groundwater dependent able management and reduced availability due to climate systems. A discussion of the existing knowledge status and change. A broader goal of the paper is also to promote and identified data and knowledge gaps is also included. elevate the role of groundwater in integrated water resourc- es management (IWRM). Sectionr 3: Adaptation options ­ a review and assessment of adaptation options to improve the resilience of ground- The analysis of the impacts of climate change on ground- water systems to risks posed by hydrological variability and water and adaptation was planned to be carried out in climate change. two phases. The first phase is reported here. It includes a literature review of the current and projected impact of Section 4: Case studies ­ a summary of three case examples hydrologic variability and climate change on groundwater where groundwater adaptation options have been em- and of adaptation options for groundwater resources. A ployed. methodology for assessing vulnerability and risk to hydro- logic variability and climate change in groundwater depen- Section 5: Conclusion dent water systems has also been developed and is part of the larger report. Several case studies have been prepared, Section 6: Recommendations which outline adaptations to improve the resilience of groundwater systems to climate change and hydrological variability in Australia, the United States of America and the United Kingdom. 15 2. ClimaTe Change, hyDrologiCal variabiliTy anD grounDwaTer 2.1 fundamental concepts to evaporate, sublimate and transpire. Water is transported from the atmosphere back to the Earth's surface as precipi- 2.1.1 Groundwaterandthehydrologic tation, falling as either rain or snow. cycle The hydrologic cycle (Figure 2.1) represents the continu- Exchange of atmospheric water to groundwater can occur ous movement of water between the atmosphere, the via infiltration of rainfall or snowmelt through the soil pro- Earth's surface (glaciers, snowpack, streams, wetlands and file. Water may also run off the Earth's surface and infiltrate oceans) and soils and rock. The term groundwater refers to groundwater via stream channels and wetlands. The to water in soils and geologic formations that are fully process by which water from the surface enters the ground- saturated. water system is called recharge. The hydrologic cycle is driven by solar energy which heats Loss of groundwater to the atmosphere occurs through the Earth's surface and causes water from the Earth's surface the process of evapotranspiration. This includes direct Figure 2.1: the hydrologic Cycle CONDENSATION Forms clouds Solar Energy PRECIPITATION EVAPORATION from surface water bodies EVAPORATION and transpiration from From oceans vegetation Human use PUMPING from aquifers Source: http://www.pvwma.dst.ca.us/hydrology/images/hydrologic_cycle.jpg 17 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options evaporation of shallow groundwater and transpiration Atlantic Oscillation (NAO) and the Interdecadal Pacific Oscil- by vegetation. Groundwater may also flow into streams, lation (IPO). The presence of, and degree of influence from, springs, wetlands and oceans, or be pumped from wells these and other natural phenomena will vary between for human use. The process by which water is lost from countries and even watersheds. groundwater is called discharge. The difference between recharge and discharge determines the volume of water in Variations in climate will induce hydrologic change. groundwater storage. Table 2.1 summarizes the variations in climate and hydrol- ogy that are projected to occur due to global warming. Any variations in climate have the potential to affect re- The potential impacts of these changes for groundwater charge, discharge and groundwater quality, either directly resources are discussed in subsequent sections. or indirectly. An example of a direct impact would be reduced recharge due to a decrease in precipitation. Sea water intrusion to coastal aquifers due to increased temper- 2.2 impacts of climate change on ature and subsequent sea level rise represents an indirect groundwater influence on groundwater quality. 2.2.1 Recharge Groundwater quantity and quality can also be affected by Groundwater recharge3 can occur locally from surface water and land use change. Examples include changes to water bodies or in diffuse form from precipitation via the groundwater pumping regimes, damming of rivers, clearing unsaturated soil zone (Döll and Fiedler, 2008). Precipitation of woody vegetation and conversion of dryland agriculture is the primary climatic driver for groundwater recharge. to irrigation. Temperature and CO2 concentrations are also important since they affect evapotranspiration and thus the portion 2.1.2 Climatechangeandhydrologic of precipitation that may drain through the soil profile to variability aquifers. Other factors affecting groundwater recharge include land cover, soils, geology, topographic relief and Climate change is "an altered state of the climate that can aquifer type. be identified by change in the mean and/or variability of its properties and that persist for an extended period, typi- The only global scale estimates of climate change im- cally decades or longer" (Bates et al., 2008). It may be due pacts to groundwater recharge are those developed to "natural internal processes or external forcings, or to per- by Döll and Florke (2005). Based on calculations from sistent anthropogenic changes in the composition of the the global hydrological model WGHM (WaterGAP Global atmosphere or in land use" (IPCC, 2007). Hydrology Model), they estimated diffuse recharge (1961­ 1990 baseline) at the global scale with a resolution of 0.5° Over the past 150 years global mean temperatures have by 0.5°. They then simulated the impacts of climate change increased with the rate of warming accelerated in the past for 2050s under a high (A2) and low (B2) greenhouse gas 25 to 50 years. It is considered very likely that this change is emission scenario. Other scenarios (e.g. 2030 time frame, largely attributed to anthropogenic influences (in particular A1B greenhouse gas emissions) were not modeled in this increased CO2 concentrations from burning of fossil fuels) work and therefore cannot be reported here. and that global warming will continue in the future (IPCC, 2007). Climate also varies in response to natural phenomena, on 3 The focus of this section is on natural recharge, not artificial seasonal, inter-annual, and inter-decadal scales. Examples recharge. Artificial recharge occurs due to excess irrigation or via intentional enhancement of recharge. The latter is commonly of these natural phenomena include the El Nino Southern known as managed aquifer recharge (MAR). MAR is discussed Oscillation (ENSO), the Indian Ocean Dipole (IOD), the North further in Section 3.4.1. 18 Climate Change, Hydrological Variability and Groundwater table 2.1: projected impact of global Warming for primary Climate and hydrologic indicators Variable Projected future change* Temperature Temperatures are projected to increase in the 21st century, with geographical patterns similar to those ob- served over the last few decades. Warming is expected to be greatest over land and at the highest northern latitudes, and least over the Southern Oceans and parts of the North Atlantic ocean. It is very likely that hot extremes and heat waves will continue to become more frequent. Precipitation On a global scale precipitation is projected to increase, however this is expected to vary geographically-- some areas are likely to experience an increase and others a decline in annual average precipitation. Increases in the amount of precipitation are likely at high latitudes. At low latitudes, both regional increases and decreases in precipitation over land areas are likely. Many (not all) areas of currently high precipitation are expected to experience precipitation increases, whereas many areas of low precipitation and high evapora- tion are projected to have precipitation decreases. Drought-affected areas will probably increase and extreme precipitation events are likely to increase in fre- quency and intensity. The ratio between rain and snow is likely to change due to increased temperatures. Sea level rise Global mean sea level is expected to rise due to warming of the oceans and melting of glaciers. The more optimistic projections of global average sea level rise at the end of the 21st century are between 0.18­0.38 m, but an extreme scenario gives a rise up to 0.59 m. In coastal regions, sea levels are likely to also be affected by larger extreme wave events and storm surges. Evapo-transpiration Evaporative demand, or potential evaporation, is influenced by atmospheric humidity, net radiation, wind speed and temperature. It is projected generally to increase, as a result of higher temperatures. Transpiration may increase or decrease. Runoff Runoff is likely to increase at higher latitudes and in some wet tropics, including populous areas in East and South-East Asia, and decrease over much of the mid-latitudes and dry tropics, which are presently water stressed. Water volumes stored in glaciers and snow cover is likely to decline, resulting in decreases in summer and autumn flows in affected areas. Changes in seasonality of runoff may also be observed due to rapid melting of glaciers and less precipitation falling as snow in alpine areas. Soil moisture Annual mean soil moisture content is projected to decrease in many parts of the sub-tropics and generally across the Mediterranean region, and at high latitudes where snow cover diminishes. Soil moisture is likely to increase in East Africa, central Asia, the cone of South America, and other regions with substantial increases in precipitation. *Relative to 1990 baseline. Source: IPCC (2007), World Bank (2009) According to the results of Döll and Florke (2005), re- ˇ significant decreases in groundwater recharge (by charge--when averaged globally for the 2050s--will in- more than 70%) for north-eastern Brazil, the western crease by 2%. This is less than the projected increases of 4% part of southern Africa and areas along the southern and 9% for annual precipitation and runoff. Geographical rim of the Mediterranean Sea variations in Döll and Florke's (2005) 2050 recharge projec- ˇ increased groundwater recharge (by greater than 30%) tions (Figure 2.2) include: across large areas, including the Sahel, Northern China, Western US and Siberia 19 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options Figure 2.2: global estimates of Climate Change impact on groundwater recharge Impact of climate change on long-term average annual diffuse groundwater recharge. Percent changes of 30-year averages groundwa- ter recharge between 1961­1990 and the 2050s (2041­2070), as computed by WGHM applying four different climate change scenarios (climate scenarios computed by the climate models ECHAM4 and HadCM3, each interpreting the two IPCC greenhouse gas emissions scenarios A2 and B2). Source: Döll and Florke (2005). ˇ potentially significant decreases in groundwater re- has not been incorporated into Döll and Florke's (2005) charge for Australia, USA and Spain, although results modeling. Also, their method only represents diffuse re- vary significantly between climate models in these charge--recharge from rivers or other surface waters were areas.4 not accounted for. These global estimates identify regions where groundwater Changes in the magnitude of groundwater recharge is potentially vulnerable to climate change. However, they will not always be in the same direction as precipitation are not appropriate for scaling down to a country or wa- changes. Recharge is not only influenced by the magni- tershed scale. Precipitation and groundwater systems can tude of precipitation, but also by its intensity, seasonality, vary significantly between watersheds and this variability frequency, and type (Figure 2.3). Other factors, for example changes in soil properties or vegetation type and water use can also affect recharge rates. van Roosmalen et al. (2007) concluded that changes to groundwater recharge rates 4 This is relative to 1961­1990 recharge rates which in many cases may be very low. Uncertainties associated with projected change were highly dependent on the geological setting of the in precipitation from global climate model models also apply here. area. 20 Climate Change, Hydrological Variability and Groundwater Figure 2.3: summary of Climate Change impacts on recharge under different Climatic Conditions High latitude regions Temperate regions Arid and semi-arid regions Recharge may occur earlier due to warm- Changes to annual recharge will vary de- In many already water stressed arid and er winter temperatures, shifting the spring pending on climate and other local condi- semi arid areas, groundwater recharge is melt from spring toward winter.In areas tions. In some cases little change may be likely to decrease.However where heavy where permafrost thaws due to increased observed in annual recharge, however the rainfalls and floods are major sources of temperatures, increased recharge is likely difference between summer and winter recharge, an increase in recharge may to occur recharge may increase be expected. E.g., alluvial aquifers where recharge occurs via stream channels, or bedrock aquifers where recharge occurs via direct infiltration of rainfall through fractures or dissolution channels. Source: Holman et al, 2001; Döll and Florke, 2005; van Vliet, 2007; Dragoni and Sukhija, 2008. During high intensity rainfall events the infiltration capacity the effects of climate change on groundwater recharge of soils may quickly be exceeded, resulting in increased run- in the Gnangara Mound, Western Australia, by modeling off and stream flow with less rain infiltrating to groundwater the impacts of increased atmospheric concentrations of (Acreman, 2000). More frequent and longer droughts may CO2 on rainfall and potential evapotranspiration regimes. lead to soil crusting and hydrophobic soils, such that during They found that the magnitude and even the direction precipitation events overland flow increases and ground- of change in recharge depends on the local soil, vegeta- water recharge decreases (Döll and Florke, 2005). In areas tion and climatic region and that ratios of the change where groundwater is recharged from surface water bodies in recharge to change in rainfall ranged from ­0.8 to 0.6 or via preferential pathways such as macropores and joints, (Figure 2.4). higher intensity rainfall is likely to lead to more groundwater recharge (Döll and Florke, 2005; van Vliet, 2007). Figure 2.4: simulated Change in recharge per unit Precipitation changes during the major recharge season are Change in rainfall under a double-Co2 climate change likely to be more significant than annual changes. Yet this will scenario in Western australia (green et al., 1997) also be influenced by antecedent conditions on a seasonal and inter-annual scale. More frequent droughts or reduced 1 Grass 1 rainfall during summer months can result in larger soil mois- ture deficits, and consequently recharge periods may be short- 2 Grass 2 ened (Acreman, 2000; Holman, 2006; Döll and Florke, 2005). Vegetation This may be exacerbated by increased temperatures and Type evapotranspiration, although the effects of climate change on 3 Tree 3 transpiration from vegetation is uncertain (Section 2.2.2). 4 Tree 4 In high latitude regions, recharge may occur earlier as warmer winter temperatures shift the spring melt from Med. Fine Sand Clay Sand Sand Loam Loam spring toward winter (van Vliet, 2007). Where permafrost thaws due to increased temperatures, increased recharge is ­0.5 ­0.0 0.5 1.0 likely to occur (Dragoni and Sukhija, 2008). d(Recharge)/d(Rainfall) The ratio of change in groundwater recharge to Grasses 1 and 2 represent perennial grasses, Trees 1 and 2 represent change in rainfall is not 1:1. Green et al. (1997) simulated pine and eucalypt canopies. Reproduced from GRAPHIC (2008). 21 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options For the Hawkesdale region in south-eastern Australia, SKM 2.2.2 Discharge (2007) modeled the impacts of climate change on ground- The impacts of climate change on groundwater discharge water recharge under different land cover, depth to water are less well understood. In part this reflects the difficulties table, geological and climatic conditions. The latter included in measuring discharge, and thus a lack of data to quantify capturing natural inter-decadal variations in climate, in ad- discharge processes (van Vliet, 2007). Historically groundwa- dition to anthropogenic climate change (further details are ter assessments have also been focused on understanding provided in the larger report). Across their modeled sce- how much water enters the groundwater system and if this narios, ratios of the change in recharge to change in rainfall is suitable for human use. Less consideration has been giv- ranged from 0 to 0.87. Where rainfall fell below the thresh- en to the ecosystems groundwater supports, such as terres- old required to negate runoff and evapotranspirative losses, trial vegetation and groundwater flow to springs, streams, zero recharge was observed to occur. wetlands and oceans. Sandstorm (1995) studied a semi-arid basin in Africa and For evapotranspiration, direct climate change impacts in- concluded that a 15% reduction in rainfall could lead to clude: (1) changes in groundwater use by vegetation due a 45% reduction in groundwater recharge. In the Murray to increased temperature and CO2 concentrations, and (2) Darling Basin (Australia) Crosbie et al. (2009) also concluded changes in the availability of water to be evaporated or trans- that the percentage change in groundwater recharge was pired, primarily due to changes in the precipitation regime. greater than the percentage change in rainfall, by a fac- tor of approximately 2.2 (Figure 2.5). Furthermore Crosbie Whilst CO2 is likely to be a significant factor in the water et al. (2009) found that even when there is no change in balance, the extent of its impact is still uncertain (Kurijt rainfall, the increase in temperature caused an increase in et al., 2008). Experimental evidence shows that elevated the vapour pressure deficit, which resulted in an increase in atmospheric CO2 concentrations tend to reduce stomatal evapotranspiration and hence a decrease in recharge. The opening in plants, and that this leads to lower transpiration decrease in recharge manifested itself as reduced discharge rates (Bethenod et al., 2001; Kurijt et al., 2008). In a study for to streams and hence reduced streamflow. This has very the Netherlands, Kruijt et al. (2008) concluded that the com- significant implications. bined effects of CO2 on evapotranspiration ranged between a few percent for short crops to about 15% for tall rough vegetation, and that this was of a `comparable but opposite Figure 2.5: Change in rainfall Versus Change in magnitude to predicted temperature-induced increases in recharge for murray darling Basin, australia evapotranspiration'. 200 Increased duration and frequency of droughts (due to in- 150 creased temperatures and increased variation in precipita- Change in Recharge (%) tion) is likely to result in greater soil moisture deficits. Where 100 soil water becomes depleted, vegetation may increasingly depend on groundwater for survival (if groundwater occurs 50 in proximity to the root zone). During dry periods this may lead to increased evapotranspiration from groundwater. 0 Indirect impacts associated with land use change may also ­50 affect groundwater evapotranspiration. For example, refor- estation for CO2 capture may draw on shallow groundwater ­100 and lower water tables (Dragoni and Sukhija, 2008). ­30 ­20 ­10 0 10 20 Change in Rainfall (%) Groundwater flow to surface water bodies will be driven Source: Crosbie et al., 2009. by relative head levels between groundwater and surface 22 Climate Change, Hydrological Variability and Groundwater water. Consequently the affects of climate change are in- 2.2.4 Waterquality direct; through alterations to recharge and other discharge In many areas, aquifers provide an important source of mechanisms (e.g. evapotranspiration). If groundwater falls freshwater supply. Maintaining water quality in these aqui- below surface water levels, groundwater discharge may no fers is essential for the communities and farming activities longer occur (and vice versa). In semi-arid and arid regions, dependent on them. Both thermal and chemical properties the dependence on groundwater to maintain baseflow in of groundwater may be affected by climate change. In shal- permanent streams is likely to be greater during periods of low aquifers, groundwater temperatures may increase due extended drought. In temperate areas where higher winter to increasing air temperatures. In arid and semi-arid areas recharge is projected (e.g. UK) it is conceivable that some increased evapotranspiration may lead to groundwater watersheds could sustain higher baseflows during sum- salinization (van Vliet, 2007). In coastal aquifers, sea level mer, even if summers become warmer and drier (Acreman, rise and storm surges are likely to lead to sea water intru- 2000). sion and salinization of groundwater resources. Changes in recharge and discharge (see above) are likely to change the Groundwater pumping also forms a mechanism for ground- vulnerability of aquifers to diffuse pollution (van Vliet, 2007). water discharge. Projected increases in precipitation vari- ability are likely to result in more intense droughts and Ranjan et al. (2006) assessed the impact of sea level rise on floods, affecting the reliability of surface water supplies the loss of fresh groundwater resources in coastal aquifers. with respect to both quantity and quality. Human demand Their study included coastal areas in the following five re- for groundwater is therefore likely to increase to offset this gions: Central America, Southern Africa, Northern Africa/Sa- declining surface water availability and, where available, will hara, around the Mediterranean, and in the Southern Asia. become a critical facet for communities to adapt to climate Climate change impacts were simulated for a high (A2) and change (Foster, 2008). low (B2) emissions scenarios and accounted for changes in groundwater recharge, as per the conceptual model Large volumes of groundwater, often of acceptable qual- provided in Figure 2.6. With the exception of the Northern ity, discharge to oceans in near shore environments. This Africa/Sahara region, Ranjan et al. (2006) found that a long- discharge process, and the capacity for recovery of ground- term trend of increasing loss of fresh coastal groundwater water, is currently poorly understood (Dragoni & Sukhija, resources was likely in all studied regions under both high 2008). and low emissions scenarios. Small islands and coral atolls, where sea level rise leads to contraction of fresh ground- 2.2.3 Groundwaterstorage water lenses, are particularly vulnerable (Kundzewicz & Döll, 2008). Groundwater storage is the difference between recharge and discharge over the time frames that these processes In areas where rainfall intensity is expected to increase, pol- occur, ranging between days to thousands of years. Stor- lutants (pesticides, organic matter, heavy metals etc) will age is influenced by specific aquifer properties, size and be increasingly washed from soils to water bodies (IPCC, type. Deeper aquifers react, with delay, to large-scale 2007). Where recharge to aquifers occurs via these surface climate change but not to short-term climate variability. water bodies, groundwater quality is likely to decline. Where Shallow groundwater systems (especially unconsolidated recharge is projected to decrease, water quality may also sediment or fractured bedrock aquifers) are more respon- decrease due to lower dilution (IPCC, 2007) and in some sive to smaller scale climate variability (Kundzewicz and cases may also lead to intrusion of poorer quality water Döll, 2008). The impacts of climate change on storage from neighboring aquifers (van Vliet, 2007). will also depend on whether or not groundwater is re- newable (contemporary recharge) or comprises a fossil Taylor et al. (2008) assessed the impact of increased heavy resource. rains on the water quality of spring discharge in Kampala, 23 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options Figure 2.6: schematic representing the loss of Fresh groundwater resources due to saltwater intrusion in Coastal aquifers P ET Freshwater level Sea level Interface 3 Recharge Salt water Fresh water Interface 2 Groundwater ow Interface 1 Freshwater loss Increases in recharge shifts the saltwater interface seaward. Decreases in recharge and/or increases in sea level will result in landward movement of the salt water interface. Source: Ranjan et al. (2006). Uganda. They concluded that increased heavy rainfall groundwater use associated with population growth has events would lead to more frequent, episodic deterioration also been a factor, particularly in arid and semi-arid areas in bacteriological quality of spring discharges, derived from where water is scarce. Future global population growth is rapid flushing of inadequately contained fecal matter in the expected to place groundwater resources under greater area. In areas where groundwater levels rise, waste stored stress. underground in the unsaturated zone may become satu- rated and contaminate the groundwater resource. Land use change also affects groundwater resources. The degree and magnitude of impact will depend on local con- ditions. In a small Sahelian catchment in Niger, Seguis et al. 2.3 impacts of non-climatic factors (2004) found that the transition from a wet period under a `natural' land cover (1950) to a dry period under cultivated Whilst climate change is likely to have adverse impacts on land cover (1992) resulted in a 30 to 70% increase in runoff. the quantity and quality of groundwater resources, in many Recharge in this catchment occurred preferentially through areas this will be dwarfed by the non-climatic impacts ponds, and thus the increased runoff caused a significant including growth in the global population, food demand and continuous water table rise over the same period. In (which drives irrigated agriculture), land use change, and this catchment, Seguis et al. (2004) concluded that the socio-economic factors that influence the capacity to ap- impacts of land use change were more important than propriately manage the groundwater resource. drought. Historically, in both developed and developing nations, In a south-western Uganda catchment, clearing of vegeta- groundwater demand has been poorly managed. Low in- tion has led to a 90% reduction in yields from local ground- vestment in groundwater investigations and management water springs (Mutiibwa, 2008). The clearing has been during the 20th Century, a time of intensive groundwater driven by population growth and the need to cultivate and use for agricultural crop production, has placed ground- settle land. Loss of vegetation cover has resulted in less water under stress (Hiscock and Tanaka, 2006). Increased interception and infiltration of rainfall, and increased runoff. 24 Climate Change, Hydrological Variability and Groundwater The dominant recharge mechanism is direct infiltration of people to use unsafe water resources or walk long distances rainfall and therefore changes in the rainfall-runoff relation- for water (Kongola, 2008). This has associated impacts for ship have resulted in a significant reduction in groundwater human health and the capacity (time) to earn an income or recharge. gain education. A range of technical and socio-economic factors have con- The livelihoods of rural populations are largely dependent tributed to the current condition of groundwater resources, on land, water and the environment with limited alterna- and these will influence their management in the future tives compared to their urban counterparts. Reduced water also. Inadequate information to inform groundwater alloca- availability can cause severe hardships. Drying up of pasture tion; lack of qualified personnel; increasing contamination and drinking water to livestock can wipe out herds of live- of water resources from agriculture, industries and mining; stock that are sources of income, family security and food. uncontrolled groundwater abstraction; lack of land use Small scale irrigation enterprises, usually reliant on shallow planning; inadequate financial capacity and a lack of educa- groundwater, may also fail (Kongola, 2008). tion and awareness amongst stakeholders are just some of the challenges that must be overcome (Kalugendo, 2008). Where increases in heavy rainfall events are projected, Muttibwa (2008) concluded that the appropriate manage- floods can wash away sanitation facilities, spreading waste ment of groundwater resources required not only a techni- water and potentially contaminating groundwater resourc- cal and financial capacity, but also `political goodwill'. es. This may lead to increased risk of diarrheal disease (Tay- lor et al., 2008). The risk of such contamination is likely to be greater in urban areas due to higher population density and 2.4 implications for groundwater concentration of source pollutants. In coastal regions, sea dependent systems and sectors water intrusion may limit the capacity of communities to cope with already large and rapidly expanding populations Groundwater dependent systems comprise those com- (Ranjan et al., 2006). munities, industries and environments that rely on ground- water for water supply. Dependence on groundwater in developing countries is high, due to either water scarcity 2.4.2 Agriculture or a lack of safe drinking water from surface water supplies. Globally, irrigated agriculture is the largest water use sector Climate change and other pressures may compromise the (Kundzewicz et al., 2007). In areas where the availability of availability and quality of groundwater resources with sig- groundwater is reduced, irrigation may become unviable, nificant implications for human and environmental health, particularly if demand for drinking water supply in the livelihoods, food security and social and economic stability. area (a higher priority) cannot be met. Alternatively, irriga- Degradation of groundwater will also increase the suscepti- tion may need to occur on an opportunistic basis during bility of poor communities to extreme events (Ranjan et al., periods of water availability or adopt alternative water re- 2006). sources (such as recycled waste water), or technologies and methods for increased water use efficiency. In areas where groundwater availability increases, agriculture may benefit. 2.4.1 Ruralandurbancommunities However shallow rising water tables may also cause prob- Shallow wells often provide an important source of drinking lems such as soil salinization and water logging. water for rural populations in developing nations. Increased demand and potentially increased severity of droughts may cause these shallow wells to dry up. With limited alterna- 2.4.3 Ecosystems tives for safe drinking water supplies (surface water may The impact of climate change is likely to accentuate the be absent or contaminated and deeper wells may not be competition between human and ecological water uses, economically feasible), loss of groundwater would force particularly during periods of protracted drought (Loaiciga, 25 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options 2003). Environmental implications include the reduction Florke, 2005). Whilst providing an indicator of potentially or elimination of stream baseflow and refugia for aquatic vulnerable regions, this global mapping in not suitable for plants and animals, dieback of groundwater dependent assessing vulnerability at national or watershed scales. Infor- vegetation, and reduced water supply for terrestrial fauna. mation and data at a sub-regional and groundwater basin In areas where salinization occurs, e.g. coastal regions, salt level are required for operational and investment purposes. sensitive species may be lost. Other sources of groundwater contamination may also adversely affect ecosystems. Watershed case studies on global climate change are a mat- ter of concern (Varis et al, 2004); however in many locations they will be constrained by a paucity of meaningful data. 2.5 uncertainties and knowledge gaps Many developing nations are data poor, and there are also many uncertainties and limitations associated with down- Quantifying impacts of climate change on groundwater scaling global climate models to this scale. There is a need is difficult and is subject to uncertainties in future climate for better database management and dissemination of in- projections (particularly precipitation) and the relative influ- formation for water resource managers. ence of other factors, e.g. vegetation response to change in carbon dioxide. Studies of climate change impacts on Current understanding of climate change impacts is poor. groundwater recharge have largely focused on quantifying However there are a number of organizations beginning to the direct impacts of changing precipitation and tempera- enhance the understanding of climate change impacts on ture patterns, assuming other parameters remain constant groundwater resources. This includes UNESCO's initiative (Holman, 2006). Few studies have addressed indirect cli- Groundwater Resources Assessment under the Pressures mate effects such as change in land use, vegetation cover of Humanity and Climate Changes (GRAPHIC), with which and soil properties (Holman, 2006; Jacques, 2006). Natural the International Groundwater Resource Assessment Centre climate variability is also often ignored with the focus typi- (IGRAC) and the International Association of Hydrogeolo- cally being on anthropogenic climate change impacts only. gists (IAH) Commission on Climate Change are partners. Whilst knowledge of climate change impacts for ground- To focus solely on the direct impacts of climate change aris- water is advancing, there does not appear to be any coordi- ing from temperature and precipitation is to neglect the nated approach for developing responses (adaptation). potentially important role of societal values and economic pressures in shaping the landscape above aquifers (Holman, GRAPHIC (2008) discuss additional knowledge and data 2006). To obtain more realistic predictions of hydrologi- gaps relevant to groundwater and climate change. cal response to the future climate, the impact of indirect consequences of climate changes--such as sea level rise, changes in agricultural practice and land use and the de- 2.6 groundwater vulnerability to climate velopment in water demand for domestic and irrigation change at a world bank regional scale purposes--and natural climate variability also need to be addressed. This will require an integrated approach that A preliminary assessment of the vulnerability of ground- considers the physical processes as well as describing the water in World Bank regions to climate change was under- plausible human developments in the future (van Roos- taken to highlight any geographies with particularly low or malen et al., 2007). high vulnerability to climate change. The assessment was developed by the authors using the basic criteria defined There is significant uncertainty in the global recharge map- below. It assesses vulnerability for 2050 climate change sce- ping (Döll and Florke, 2005). This is due to uncertainties in narios, assuming all non-climatic conditions as current. The projected precipitation and the inability of the Döll and assessment is at regional scale and is intended as a general Florke's (2005) recharge modeling to capture preferential re- indicator only. As a high level assessment it might help charge from surface water bodies such as streams (Döll and guide priorities for further work to more precisely assess 26 Climate Change, Hydrological Variability and Groundwater vulnerability to climate change and to build the resilience of ˇ adaptive capacity: wealth, as measured by per capita groundwater dependent systems. It is not intended to as- gross national income (GNI; World Bank, 20085) sess country-scale priorities. Groundwater use is used as an indicator of sensitivity to cli- Four criteria were considered in the regional vulnerability mate change. The second and third criteria were indicators indicator assessment (Table 2.2): of exposure and GNI was used to indicate adaptive capacity. These factors were combined to provide a vulnerability in- ˇ sensitivity: current level of exploitation of groundwater dicator. Adaptive capacity and the combination of exposure resources ­ as indicated by the use of groundwater and sensitivity indicators were weighted evenly. Weighting relative to average annual recharge (after IGRAC, 2004); to sea level rise and storm surge risk was reduced to reflect ˇ exposure: the magnitude and trend in changes in rates its uneven application to World Bank regions. of groundwater recharge under 2050 climate change projections (after Döll and Flörke, 2005); While there remains significant uncertainty with this as- ˇ exposure: the exposure of regional water resources to sessment, it suggests that groundwater in the World Bank sea level rise and contamination due to storm surge Europe and Central Asia region is the least vulnerable to (based on the authors' assessment of cyclone inci- dence, the extent of coastal areas in the region and population density in these areas); 5 Data from http://go.worldbank.org/GKIIAZEJR0 table 2.2: preliminary assessment of Vulnerability of groundwater in World Bank regions to Climate Change adaptive sensitivity exposure capacity Climate World Bank utilization of change impact slr1 & storm region groundwater on recharge surge exposure per capita gni1 Vulnerability2 East Asia & Pacific Moderate Increase Medium Moderate Moderate Europe & Central Low Increase Low High Low Asia Latin America & Moderate Reduction Medium Moderate Moderate Caribbean Middle East & High Uncertain Low Moderate Moderate North Africa South Asia Moderate Negligible High Low High Africa Moderate Reduction Low Low High SLR ­ sea level rise; GNI ­ gross national income (in $US) Vulnerability assessed from the sum of average of sensitivity and exposure ratings and adaptive capacity rating. Groundwater utilization ­ low (2), moderate (4), high (6) Impact on recharge ­ increase (2), uncertain/negligible (4), reduction (6) SLR exposure ­ low (1), medium (2), high (3) Per capita GNI ­ low (6), moderate (4), high (2) ­ relative to each other Low vulnerability (<6), Moderate (6­9), High (>9) 27 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options the effects of climate change. This reflects the relatively Country-to-country differences in vulnerability are expected low level of utilization of groundwater, the projected to be large, with this regional scale analysis most likely increase in rainfall (in many areas), minimal exposure of masking important `hot spots' of climate change vulnerabil- groundwater to risks from sea level rise and storm surge ity. A country level analysis, using similar criteria, but based and higher per capita income. Groundwater resources in on more definitive information is warranted to establish the South Asia and Africa regions were considered to be clearer priorities for further work. Such an assessment is be- most vulnerable. yond the scope of this review. 28 3. aDapTaTion To ClimaTe Change 3.1 introduction butes fall outside the coping range of the system, resulting in socio-economic and/or environmental harm. In some Whatisadaptation? areas, human-induced climate change threatens to change Groundwater dependent systems have the capacity to the hydrological environment such that its state is outside cope with some level of hydrological variability (in quality the system's coping range more frequently, potentially per- and quantity or water) without impairment (Figure 3.1). This petuating that harm (Figure 3.1). `coping range' varies with the sensitivity of the groundwa- ter dependent system to changes in various groundwater Adaptations are adjustments made in natural or human sys- attributes (e.g. water quality, depth, pressure, discharge tems in response to experienced or projected climatic con- flux). Extremes of natural climatic variability (e.g. prolonged ditions or their beneficial or adverse effects or impacts (Smit climatic drought) may mean that some groundwater attri- et al., 2001). In the context of this report (and Figure 3.1) they are concerned with reducing the vulnerability of groundwater dependent systems to climate change and Figure 3.1: Coping range and adaptation to human- hydrological variability. Adaptations are essentially manage- induced Climate Change (redrawn from Willows and ment responses to risks associated with climate variability Connell, 2003) and climate change. Figure 3.2 (from Smit et al., 2000) uses three primary ques- tions to conceptualize climate adaptation: (1) adaptation to what, (2) who or what adapts and (3) how does that adapta- Water table depth (m) tion occur? Identification and/or development of adaptations should reflect an understanding of these three components. Prior to use or implementation, adaptations should also be evaluated to determine whether they are fit-for-purpose and Stationary climate cost-effective. Adaptations to climate change and variability must also complement or include adaptations to non-climate pressures or conditions that may affect the system. Human-induced climate change Time Adaptation may occur as the result of planned action (e.g. The graph shows variation in a hypothetical hydrological parame- Figure 3.2) or autonomously. Natural and human systems ter (e.g. water level in shallow aquifer) under stationary conditions that are periodically challenged by climatic and hydrologi- and human-induced climate change (the solid black line shows cal extremes tend to adapt to minimize harm if challenged the mean state). In sequences of dry years, water levels may fall below the depth of a well or bore (which would define the sys- again in future. Planned adaptation is a pre-emptive re- tem's coping range) and some form of harm is experienced. In this sponse based on an assessment of future climate and hy- example, human-induced climate change is projected to initially drological risks. result in increased frequency of years during which water levels fall below the level from which water can be extracted. As change progresses, this state becomes permanent. With adaptation (e.g. extending the well or sinking a deeper bore) the system's coping forms of adaptation range is extended so that permanent harm is avoided. Note that adaptations are rarely required to respond to a single stimulus, Burton (1996) developed a useful typology of climate such as in this example change adaptation options (Figure 3.3), in which he 29 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options Figure 3.2: Conceptualization of adaptation of a groundwater dependent system to Climate Change and Variability (redrawn from smit et al., 2000) What is adaptation? Adaptation to what? Non-climate forces Climate related stimuli & conditions ˇ Groundwater attributes (quality, quantity, level etc.) ˇ Time & spatial scales Who or what adapts? How does adaptation occur? Groundwater dependent system Types ˇ De nition ˇ Processes ˇ Characteristics ˇ Outcomes How good is the adaptation? Evaluation ˇ Criteria ˇ Principles proposed eight broad types, which fall into five groups of undertaken to reduce the frequency of events that take risk responses, as follows: the system outside its coping range. In the example illustrated in Figure 3.1, this could include actions that Accept the risks ­ in which climate risks are accepted and increase groundwater recharge (e.g. vegetation cover no action is undertaken to change the exposure or (di- change, artificial recharge) to maintain groundwater rect) sensitivity of the system to them. On those occasions levels within the range accessible to the well or bore. when the system's coping range (Figure 3.1) is approached ˇ Modify the consequences of (or sensitivity to) a climate or exceeded, the associated losses are either borne (#2 or related hazard ­ in which actions are undertaken in Figure 3.3) by those directly exposed or shared (#1 in to extend the coping range of the system and pre- Figure 3.3) among a broader group. Insurance is an example vent adverse impacts (#4 in Figure 3.3). The case from of the latter. Bearing the loss is a form of adaptation that Figure 3.1 of extending the well to a greater depth to would typically only apply when losses are either small in maintain access to water is one example of this type relation to the cost of other forms of adaptation or when of adaptation. In addition to physical works and mea- they cannot be avoided (e.g. loss of ice cover in montane sures, this type of adaptation may include changes in areas subject to increased temperature). institutional or regulatory arrangements and establish- ment of markets (Figure 3.3). ˇ Modify the likelihood of (or exposure to) a climate or ˇ Avoid the risk ­ by either changing the sensitivity (#5 in related hazard (#3 in Figure 3.3) ­ in which actions are Figure 3.3) or exposure (#6 in Figure 3.3) of the system 30 Adaptation to Climate Change Figure 3.3: Classification of adaptation options (redrawn from Burton, 1996) 1. Share the loss 2. Bear the loss Structural or technological 3. Modify the events Legislative, regulatory, nancial 4. Prevent the e ects Institutional or administrative Adaptation options 5. Change use Market-based 6. Change location On-site operations 7. Research 8. Education & behavioural change to climate risks. For a groundwater dependent system, would be considered in the second pass of the vulnerability the former may involve reducing the reliance of the assessment process. system on irrigation by, for example, moving from a perennial crop that must be irrigated every year to an annual one that is grown opportunistically, when wa- 3.2 adaptation options for risks to ter is available. The latter option may involve moving groundwater dependent systems irrigated cropping to another location with a more reli- from climate change and hydrological able water supply. variability ˇ Build adaptive capacity ­ undertake research (#7 in Figure 3.3) to better understand the risks faced, the sys- This section contains a review of adaptation options for risks tem's vulnerability to climate change and hydrological to groundwater dependent systems from climate change variability and/or improve or extend the range of adap- and hydrological variability. It is structured around the five tations. Education and behavioral change programs (#8 groups of options discussed in the previous section, where in Figure 3.3) could be developed and implemented to they are appropriate and five main groundwater process improve stakeholders' and communities' understand- themes (Figure 3.4): ing of risks and management responses. Such cam- paigns might also empower groups to develop new ˇ Managing groundwater recharge adaptations or apply existing adaptations (across types ˇ Management of groundwater storage #3­5 in Figure 3.3) more effectively or extensively. ˇ Protection of groundwater quality ˇ Managing demand for groundwater All of these types are applicable to the groundwater vulner- ˇ Managing groundwater discharge ability assessment framework. Acceptance of risk may be the adaptation choice in the first pass of the vulnerability In most instances, `accept the risk' options (#1 and #2 in assessment (Figure 3.1), in situations where there is low Figure 3.3) are limited or need not be specified. These op- vulnerability or where there is no meaningful prospect of tions are mostly likely to be considered where risk is low avoiding an impact (or consequence) should the adverse relative to the cost of adaptation or where other forms of climate or hydrological state be realized. Other options adaptation are unlikely to be effective in mitigating risk. 31 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options Figure 3.4: groundwater adaptation options, Based on groundwater processes and location in the landscape Many of the options that fall within the `building adaptive of adaptation to be implemented successfully, rather than capacity' group are cross-cutting and at least partially ap- managing or avoiding climate or hydrological risks directly. ply to multiple themes. These are introduced in a separate They fall into several categories, as noted in section 3.1 section (below), preceding the discussion by groundwater (Table 3.1). themes. Applicable adaptive capacity adaptations are also listed for the various groundwater themes. Adaptation op- tions in this section are relevant under situations in which 3.2.2 Managinggroundwaterrecharge climate change and hydrological variability reduce the Groundwater recharge areas may be managed to protect security of groundwater supply and increase the vulner- or enhance water resources and to maintain or improve ability of the water dependent system. In contrast, Section water quality. While the latter is also covered in section 3.3 deals with adaptations to situations in which climate 3.2.3, it is relevant here as activities in groundwater recharge change is projected to result in groundwater recharge and/ areas that lead to groundwater contamination also reduce or discharge increasing to the point of adverse impact on a resource availability. Potential adaptations are outlined in water dependent system. Table 3.2. 3.2.1 Buildingadaptivecapacityfor 3.2.3 Protectinggroundwaterquality groundwatermanagement Climate change and hydrological variability may affect the Adaptive capacity building options are generally concerned quality of groundwater available for use in a groundwater with providing the necessary conditions for other forms dependent system. This is particularly true of groundwater 32 Adaptation to Climate Change table 3.1: adaptation options: Building adaptive Capacity adaptation option group adaptations Social capital ˇ Education and training ­ to improve community and stakeholder understanding of climate risks and their capacity to participate in management responses and/or generate, modify or apply These options are concerned adaptations. with enabling communities to understand climate and hydro- ˇ Governance ­ devolve some level of responsibility for planning and management of groundwa- logical risks and actively partici- ter to local communities to increase local `ownership' of problems and responses pate in management responses. ˇ Sharing information ­ instigate processes for sharing of information regarding climate risks and responses within and between vulnerable communities. Resource information ˇ Understanding climate ­ analysis of historical and palaeoclimate information to understand the natural drivers of climate variability and links between interannual to interdecadal climate modes Gathering and providing in- (e.g. El Nińo Southern Oscillation, Pacific Decadal Oscillation) and climate risks. Development of formation on climate risks and historical and synthetic climate datasets for climate impact studies. the groundwater system being managed. ˇ Climate change projections ­ developing downscaled climate change projections for the area of interest. ˇ Quantify the groundwater system ­ understand the scale and characteristics of the aquifer(s); recharge, transmission and discharge processes; water balance (including use); water quality etc. ˇ Monitoring, evaluation and reporting ­ of the state of the groundwater resource, level of use, vulnerability to various threatening processes and effectiveness of climate and other adaptations. Research & development ˇ Climate impact assessments ­ studies to better define the nature of projected climate change impacts on the groundwater system and the associated climate and hydrological risks. Research and development activities to improve the effec- ˇ Management of groundwater recharge ­ methods to enhance groundwater recharge and water tiveness of adaptive responses availability. to climate change and hydro- ˇ Management of groundwater storage ­ technologies, water management and other practices to logical variability. maximize groundwater storage capacity and resource availability. ˇ Protection of water quality ­ technologies and management systems to enable treatment and reuse of contaminated water and avoid contamination of higher quality water by water of lesser quality. Protection of island and coastal aquifers from effects of sea level rise. ˇ Managing demand for groundwater ­ technologies and management practices that: improve the efficiency of urban and agricultural uses of water; reduce water quality requirements of non- potable uses; or reduce the need for water. ˇ Management of groundwater discharge ­ land management practices to reduce unwanted dis- charge of groundwater (especially) by non-indigenous woody vegetation. ˇ Markets ­ improved arrangements for operation of markets for water and related environmental services. ˇ Governance and institutional arrangements ­ improved methods for governance and steward- ship of groundwater resources. Governance & institutions ˇ Conjunctive management of surface water and groundwater in rural areas. Integrated water cycle management (including various potable and non-potable sources in urban areas). Improving governance and institutional arrangements for ˇ Multi-jurisdictional planning and resource management arrangements for large scale aquifer groundwater resource man- systems that cross jurisdictional boundaries. agement. Improved planning ˇ Defining water allocations based on resource share rather than volume. regimes for groundwater and associated human and natural ˇ Set and regulate standards for (e.g.) groundwater resource and land use planning, water gover- systems. nance, environmental management, water quality, resource information, water use efficiency (in agricultural, industrial and urban settings). (continued on next page) 33 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options table 3.1: adaptation options: Building adaptive Capacity (continued) adaptation option group adaptations ˇ Set and enforce a cap on level of utilization of groundwater within a management unit. Cap should be based on the defined sustainable yield (accounting for robust understanding of climate risks and environmental water requirements of groundwater dependent ecosystems [GDEs]) unless there is to be planned mining of an historical groundwater resource. Cap and wa- ter allocations to be reviewed and reset periodically to account for changed management and development objectives and changes in climate and resource availability. ˇ Human needs water reserve ­ secure allocation of groundwater to meet basic human needs in groundwater dependent communities. ˇ Environmental water reserve ­ secure allocation of groundwater to meet requirements of GDEs. ˇ Measurement and public reporting of groundwater use. ˇ Drought response planning. Markets ˇ Markets ­ establishment and operation of markets for and trading of water within a groundwater Establishment and operation of system. Market to determine the price for water. markets for water and associ- ˇ Property rights ­ establish clear title and property rights to groundwater. ated environmental services. ˇ Include generation of recharge and surface water flows in water markets to enable payments by water users to owners and managers of land generating water of appropriate quality. table 3.2: adaptation options: managing groundwater recharge adaptation option group adaptations Modify exposure to climate ˇ Manage or reduce the level of woody vegetation cover to optimize groundwater recharge (while risk (#3) protecting ecological values and avoiding erosion etc.). ˇ Managed aquifer recharge (MAR; or other forms of artificial recharge) in/near urban and rural settings to capture and use: ˇ urban storm water, including use of detention ponds and infiltration systems; ˇ treated wastewater from industrial facilities and urban wastewater treatment plants; ˇ overland flows ­ (e.g.) via capture in dams that are designed to leak and recharge water tables; ˇ river flows ˇ Adjust land management practice in groundwater recharge areas to maximize water table re- charge and reduce overland flows--for example through maintaining ground cover, contour banks, Keyline farming systems etc. ˇ River regulation to maintain flows over recharge beds for alluvial aquifers. Modify sensitivity to climate No options applicable risk (#4) Avoid risk (#5, #6) ˇ Land use planning controls that limit industrial forestry plantation development in key recharge areas. ˇ Land use planning and environmental management controls to avoid development of industrial or other facilities, in key recharge areas, that pose high risk of aquifer contamination. (continued on next page) 34 Adaptation to Climate Change table 3.2: adaptation options: managing groundwater recharge (continued) adaptation option group adaptations Build adaptive capacity (#3- ˇ Land use planning and environmental management controls to regulate developments in key #5, #7) recharge areas that increase vulnerability of groundwater system. ˇ Water allocation policy framework that incorporates impacts of land use on groundwater recharge and generation of surface flows. Land use changes with high water requirements re- quired to purchase entitlement to intercept groundwater recharge or surface flow. Note: # refers to the adaptation option type in Figure 3.3. resources on small islands and coastal areas that are pro- or where increased pressure on groundwater resources jected to be subject to sea level rise. It is also true where leads to increased use and greater risk of contamination reduced security of supply leads water resource managers of a high quality aquifer by any overlying or underlying to include lower quality water in the supply stream (e.g. poorer quality aquifers. Adaptation options are outlined in through MAR using storm water or treated waste water) Table 3.3. table 3.3: adaptation options: protecting groundwater Quality adaptation option group adaptations Modify exposure to climate risk ˇ Regulate surface water and groundwater levels in rivers, lakes and surface water storages and (#3) shallow water table areas with potential acid sulfate soils to avoid activation and acid contami- nation of surface waters and groundwater. ˇ Construct bore fields in coastal aquifers to drawdown the salt water aquifer and protect fresh- water from incursion as sea levels rise. ˇ Use MAR or other forms of artificial recharge of freshwater to coastal aquifers--to maintain heads in freshwater and protect aquifer from incursion by salt water as sea levels rise. ˇ Manage utilization/drawdown of groundwater to avoid contamination of higher quality groundwater by poor quality water in overlying or underlying systems. Modify sensitivity to climate ˇ Treatment of low quality water (e.g. desalination, filtration) to a standard appropriate for par- risk (#4) ticular uses. Avoid risk (#5, #6) ˇ Land use planning and environmental management controls to avoid development of indus- trial or other facilities that pose high risk of contaminating important water resource aquifers. Build adaptive capacity (#3-#5, ˇ Research to define sustainable yield and quality of aquifer systems--to ensure adequate water #7) quality maintained. ˇ Land use planning and environmental management controls to regulate developments that pose a high risk of contamination to aquifers. ˇ Education and behavior change campaign, with appropriate monitoring and regulatory sup- port, to emphasize avoidance of contamination of water resource aquifers industrial facilities, fuel or other chemical storages etc. ˇ Research to develop water treatment processes that are less expensive and require less energy. ˇ Develop water quality standards that can be applied to different uses. Supply water to meet these standards. Note: # refers to the adaptation option type in Figure 3.3. 35 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options table 3.4: adaptation options: managing groundwater storages adaptation option group adaptations Modify exposure to climate risk (#3) ˇ Increase storage capacity in aquifers--through hydrofracturing, dissolution (in karst sys- tems) or pressurization of cavities. ˇ Increase storage availability in aquifers prior to expected periods of high recharge. ˇ MAR and other forms of artificial recharge to maximize use of available water and storage capacity in aquifers. ˇ Re-inject water from mine dewatering operations into aquifer down gradient of mine (where of useful quality) rather than run to waste. Modify sensitivity to climate risk No options applicable (#4) Avoid risk (#5, #6) No options applicable Build adaptive capacity (#3-#5, #7) ˇ Research and/or resource assessments to improve understanding of aquifer properties and define opportunities and management practices for more effective storage manage- ment. ˇ Develop technical and analysis skills in groundwater resource managers to operate aqui- fers as groundwater storages. Develop monitoring infrastructure to support such manage- ment. ˇ Develop seasonal and longer term forecasting/projection of groundwater resources based on well developed understanding of main climate drivers for aquifer. Base seasonal and long-term allocations on understandings of water availability. Note: # refers to the adaptation option type in Figure 3.3. 3.2.4 Managinggroundwaterstorages adaptation to climate change. This will require greater atten- tion to management of demand for groundwater and for While aquifers are recognized as underground water storag- conjunctive management with surface water. It may also be es, they are rarely operated with the same level of precision possible to use groundwater as a store for surplus surface and control as major surface water storages. Opportunities water flows during periods of abundant supply for use dur- exist (Table 3.4) to manage groundwater storages more ef- ing periods of surface water scarcity. fectively, and reduce the vulnerability of systems that de- pend on them to climate change and hydrological variability. 3.2.6 Managementofgroundwater 3.2.5 Managingdemandfor discharge groundwater Aquifer systems discharge water to the land surface, rivers, Climate change adaptations for water resources most fre- lakes, wetlands or to near or off-shore marine environ- quently operate on demand management. In many cases, ments. Discharge, recharge and utilization are in a state the adaptations for groundwater dependent and surface of dynamic equilibrium, such that changes in recharge water dependent systems will be identical. Options are out- or utilization ultimately result in a change in discharge. In lined in Table 3.5. some settings, it is possible to increase resource availabil- ity (for use by human systems) by reducing groundwater In areas where climate change reduces supply security discharge. Potential climate change adaptation options for surface water resources, it is likely that there will be in- relating to management of groundwater discharge are out- creased focus on utilization of groundwater resources as an lined in Table 3.6. 36 Adaptation to Climate Change table 3.5: adaptation options: managing demand for ground adaptation option group adaptations Accept the risk (#1, #2) ˇ Crop insurance for drought-related crop or livestock production failures. ˇ Welfare or related support payments to primary producers experiencing drought-related crop or livestock production failures Modify exposure to climate risk ˇ Effectively cap artesian bores to reduce or eliminate wastage. (#3) ˇ Use pipes or sealed channels to distribute water from groundwater pumps and/or artesian bores to point of use to reduce or eliminate waste from seepage or evaporation. ˇ Use or improved use of seasonal forecasts and water allocation projections in crop selection and decisions on area to irrigate. ˇ Maintain water reticulation systems (where they exist) to reduce leakage and wastage. Apply appropriate standards of construction and materials to water supply systems to reduce losses. ˇ Develop system of water restrictions to apply to domestic and industrial consumption during periods of supply scarcity. ˇ Secure and maintain environmental water provision for groundwater dependent ecosystems. ˇ Substitute use of high quality groundwater for lower quality groundwater or water from other sources (e.g. treated waste water) as appropriate to the use. ˇ Use MAR to `bank' groundwater for use during periods of scarcity of surface water supplies. Modify sensitivity to climate ˇ Measure use of groundwater. risk (#4) ˇ Improve on-farm efficiency of water use--e.g. control deficit irrigation (where appropriate to crop), improved irrigation scheduling, use of more efficient application methods (i.e. sprays, drip irrigators or underground irrigation rather than flood, furrow or overhead sprinklers). ˇ Select crops with lower water requirements and/or higher value per unit of water required. ˇ Achieve balance of perennial horticulture (with high sensitivity to water shortage) and op- portunistically irrigated annual crops in order to match water use with the projections of water resource availability. ˇ Substitute irrigation production for dryland agriculture to the extent required by the level of irrigation supply. Avoid risk (#5, #6) ˇ Land use planning to limit urban and/or agricultural development to levels consistent with current and projected water supply availability. Build adaptive capacity (#3-#5, ˇ Conjunctive management of surface water and groundwater in rural areas. Integrated water #7) cycle management (including various potable and non-potable sources in urban areas). ˇ Water allocation framework for groundwater use that limits allocations to sustainable yield (unless there is planned depletion of historical reserves). Water allocations to be reviewed and reset periodically to account for changed management and development objectives and changes in climate and resource availability ˇ Multi-jurisdictional planning and resource management arrangements for large scale aquifer systems that cross jurisdictional boundaries. ˇ Set and regulate standards for (e.g.) groundwater resource planning, water governance, envi- ronmental management, water quality, resource information, water use efficiency (in agricul- tural, industrial and urban settings). ˇ Development and implementation of economic tools (for example pricing/charges/tariffs for groundwater within an aquifer system). Pricing to reflect demand and any costs of supply and treatment. Where appropriate, more complex economic markets could be established. (continued on next page) 37 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options table 3.5: adaptation options: managing demand for ground (continued) adaptation option group adaptations ˇ Defining water allocations based on resource share rather than volume. ˇ Water resource managers to provide early advice to irrigators on water allocations. ˇ Human needs water reserve--secure allocation of groundwater to meet basic human needs in groundwater dependent communities. ˇ Environmental water reserve--secure allocation of groundwater to meet requirements of GDEs. ˇ Measurement and public reporting of groundwater use. ˇ Research to develop more water efficient irrigation and agricultural production systems and crops. ˇ Education and behavior change campaign to increase adoption of existing (and any new) ad- aptations for agricultural water use efficiency. ˇ Education and behavior change campaign to raise awareness of water conservation issues and practices and change attitudes and behaviors. ˇ Community-level participation in water resource planning processes, especially for irrigation. ˇ Stepped pricing structure for domestic and industrial water use--with price per unit volume increasing in multiple steps as consumption extends beyond basic needs. Note: # refers to the adaptation option type in Figure 3.3. table 3.6: adaptation options: managing groundwater discharge adaptation option group adaptations Modify exposure to climate risk (#3) No options applicable Modify sensitivity to climate risk (#4) No options applicable Avoid risk (#5, #6) ˇ Avoid or limit establishment of industrial forestry plantations or other deep-rooted, high water use species in areas with shallow, fresh groundwater that is used for other pur- poses. Build adaptive capacity (#3-#5, #7) ˇ Land use planning controls that enable restrictions on the extent to which high water use species are established in areas with shallow, fresh groundwater that is used for other purposes. ˇ Market mechanisms that account for groundwater uptake by land uses (e.g. forestry plan- tations) in a consistent way with other direct uses of groundwater. Note: # refers to the adaptation option type in Figure 3.3. 3.3 managing for increased groundwater (2005; for groundwater; Figure 2.2) present data that proj- recharge ects increase surface flows and groundwater recharge under some emissions scenarios. Areas projected to have While it is the case that the latest climate change projec- increased recharge include some where water is currently tions (IPCC, 2007) suggest a worsening of water security in short supply (e.g. parts of the Sahel region of Africa, parts in many nations, this is not always the case. Kundzewicz of the Arabian Peninsula, north-east China) and others (e.g. et al. (2007; for surface water flows) and Döll and Florke Siberia) where it is not. 38 Adaptation to Climate Change Increased rainfall and recharge in some areas may, other enhance groundwater recharge. It forms one of the `manag- factors being equal, lessen the vulnerability of groundwater ing aquifer recharge' adaptation responses listed in Table 3.2 dependent systems. However it is conceivable that in some and is increasingly being considered as an option for im- locations, increased recharge associated with changes in cli- proving the security and quality of water supplies in areas mate and hydrological variability may make some aspect of where they are scarce (Gale, 2005). such systems more vulnerable. Such circumstances include, for example, hydrogeological settings in which increased MAR is among the most significant adaptation opportuni- recharge results in the development of shallow water tables ties for developing countries seeking to reduce vulnerability and salinization of land and water resources (such as has to climate change and hydrological variability. It has several occurred in parts of southern Australia in response to the potential benefits, including: storing water for future use, replacement of native woody vegetation with agricultural stabilizing or recovering groundwater levels in over-exploit- crops and pastures; NLWRA, 2001) or geological instability. ed aquifers, reducing evaporative losses, managing saline intrusion or land subsidence, and enabling reuse of waste Potential options for adapting to increased groundwater or storm water. recharge are outlined in Table 3.7. Implementation of MAR requires suitable groundwater storage opportunities. Falling water levels or pressures in 3.4 examples of adaptation to climate aquifers in many regions throughout the world are creat- change and hydrological variability ing such opportunities, either as unsaturated conditions in from developing countries unconfined aquifers or as a pressure reduction in confined aquifers. However, MAR is not a remedy for water scarcity 3.4.1 Managedaquiferrecharge in all areas. Aquifer conditions must be appropriate and Managed aquifer recharge (MAR) involves building infra- suitable water sources (e.g. excess wet season surface structure and/or modifying the landscape to intentionally water flows or treated waste water) are also required. MAR table 3.7: adaptation options: managing increased groundwater recharge adaptation option group adaptations Modify exposure to climate ˇ Change land use or management to increase woody or other higher water use vegetation cover. risk (#3) ˇ Establish deep rooted vegetation in areas subject to instability if seasonally water-logged. ˇ Construct surface or sub-surface drainage in discharges to intercept groundwater and drain to appropriate location (e.g. stream for fresh water, evaporation basin for saline water). ˇ Groundwater pumping to hold water table at a safe depth in the vicinity higher value agricultural or environmental assets and population centers. ˇ Increase use of groundwater for irrigation or other purposes. Modify sensitivity to climate ˇ Establish high water use vegetation in groundwater discharge areas (that are adapted to soil and risk (#4) water salinity) to increase groundwater discharge. ˇ Establish salt tolerant vegetation (with commercial use in grazing or cropping) in salinized, shal- low water table areas. Avoid risk (#5, #6) No options available Build adaptive capacity (#3- ˇ Research and development to introduce farming and other management systems that reduce #5, #7) the vulnerability of natural and human systems to the consequences of increased recharge. Note: # refers to the adaptation option type in Figure 3.3. 39 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options potential should be determined in any particular country or being deployed and sound and integrated management of region before activities commence. water resources6. MAR may not succeed as a stand-alone adaptation to scar- Detailed planning and assessment are required to deter- city of groundwater supply. Its implementation should also mine whether MAR is a viable adaptation option. This may be accompanied by demand management (Table 3.5) and be carried out a national and watershed scale. Three funda- capacity building (Table 3.1) measures. Without these mental planning steps should be considered: MAR may fail, particularly where aquifers are overex- ploited or where poor selection of the MAR site and/or ˇ Water availability ­ assess the availability and quality of type occurs due to lack of appropriate knowledge (Dil- excess wet season surface water flows or other poten- lon, pers. comm., 2008). tial sources. The frequency and volume of availability of suitable water must be assessed for each planning re- MAR methods may be grouped into the following broad gion, as must the influence of natural climate variability approaches (Figure 3.5): and projected human-induced change. ˇ Evaluate the hydrogeological suitability of the MAR site ˇ Spreading methods ­ such as infiltration ponds, soil- or region ­ which largely depends on ease of injecting aquifer treatment, in which overland flows are dis- and recovering the water, the aquifer storage capacity persed to encourage groundwater recharge; and the aquifer's resistance to clogging. ˇ In-channel modifications ­ such as percolation ponds, ˇ Feasibility - the costs, benefit and feasibility of con- sand storage dams, underground dams, leaky dams structing and operating a MAR scheme, including and recharge releases, in which direct river channel those associated with transporting the recovered MAR modifications are made to increase recharge; water to demand centers needs to be determined. ˇ Well, shaft and borehole recharge ­ in which infra- structure are developed to pump water to an aquifer MAR will not be appropriate in some hydrogeological set- to recharge it and then either withdraw it at the same tings and for some classes of water. Various MAR options or a nearby location (e.g. aquifer storage and recovery, exist and are appropriate to parts of at least some World ASR); Bank regions. ˇ Induced bank infiltration ­ in which groundwater is withdrawn at one location to create or enhance a hydraulic gradient that will lead to increased recharge mar example: sand dams in kenya (e.g. bank filtration, dune filtration) ˇ Rainwater harvesting ­ in which rainfall onto hard sur- Sand dams are made by constructing a wall across a river- faces (e.g. building roofs, paved car parks) is captured bed, which slows flash floods/ephemeral flow and allows in above or below ground tanks and then allowed to coarser sediment to settle out and accumulate behind the slowly infiltrate into soil. dam wall. The sedimentation creates a shallow artificial aquifer which is recharged both laterally and vertically by There are several common operational issues experienced stream flow (Gale, 2005). by MAR schemes (Gale, 2005). These include: clogging of wells, stability of infrastructure under operating conditions, Since 1995, over 400 sand dams have been constructed protection of groundwater quality, operation and manage- in the Kitui District of Kenya, supported by the SASOL ment of the scheme, ownership of the stored water, moni- toring, loss of infiltrated/injected water, policy and cultural acceptability and related stakeholder communications. Suc- 6 An IAH (International Association of Hydrogeologists) Com- mission on MAR are currently working with UNESCO to provide cessful operation requires appropriate training for operators, information and education resources about MAR, see: www.iah. access to successful demonstrations of the technologies org/recharge/. 40 Adaptation to Climate Change Figure 3.5: examples of managed aquifer recharge (mar) approaches ASR: aquifer storage and recovery; ASTR: aquifer storage, treatment and recovery, STP: sewage treatment plant. Source: Peter Dillon (pers. comm., 2008) 41 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options Foundation (Figure 3.6; Foster and Tuinhof, 2004). Each of White et al. (2007) examined the impact of both ENSO- these dams provides at least 2,000 m3 of storage and has related droughts and human influences on freshwater been constructed by local communities using locally avail- availability, and assessed potential adaptation strate- able material. The benefits identified through this program gies to protect water resources and reduce risks for the include: water supplies more readily available in the dry sea- densely populated central Pacific atoll, Tarawa, Republic son, enhanced food security during drought periods, and of Kiribati. Whilst focused on an atoll environment, the less travel time to obtain water supply. findings from this work are applicable to many island and coastal regions, and the principle of recharge zone pro- Sand dams are not appropriate for all locations. They require tection is common for all areas where fresh groundwater unweathered and relatively impermeable bedrock at shal- is available. low depth; the dominant rock formation in the area should weather to coarse, sandy sediments; sufficient overflow is Water supply for Tarawa's reticulated system is extracted required for fine sediments to be washed away; and risk of from freshwater lenses in groundwater reserves. During buildup of soil and groundwater salinity needs to be low. drought periods, almost all rainwater tanks are exhausted, Cooperative effort, ownership and ongoing maintenance the thickness of the fresh groundwater lens decreases, by the local community are also necessary for the success many domestic wells become saline and saline groundwa- of these schemes (Foster and Tuinhof, 2004). ter causes the death or severe dieback of mature bread-fruit trees. However, provided pumping occurs at a sustain- able rate, large freshwater lenses have historically survived 3.4.2 Groundwaterprotection: through extended droughts with only moderate increases adaptationsandchallenges in salinity. foralowatoll Thin lenses of fresh groundwater floating over seawater In order to preserve the freshwater resource and supply for comprise the major source of water supply in many atolls. drought periods in Tarawa, it is critical to reduce contami- Limited land area, permeable soils and limited vertical nation risk to groundwater. Whilst traditional practices in relief constrain surface water storage and availability low-density populations have evolved to minimize contam- (White et al, 2007). Fresh groundwaters in these environ- ination risk--for example, defecation on beaches down- ments are becoming increasingly vulnerable, threatened gradient from recharge areas and keeping pigs in pens in by sea level rise, drought, increasing populations and land groundwater discharge zones--these are often in conflict use change. with contemporary land use trends and behavioral patterns. Figure 3.6: Cross section of sand dam structure (from Foster and tuinhof, 2004) 42 Adaptation to Climate Change In particular, the keeping of pigs and market gardens in 3.5 Discussion groundwater source areas provide contamination problems for Tarawa. 3.5.1 Avoidingadaptationdecision errors Historical adaptation measures have been applied with Decisions to apply climate change adaptations are made in limited success. Installation of reverse osmosis desalina- an uncertain environment. Even so, decision makers need tion units during previous drought periods failed due to to consider the risks associated with the future being dif- intermittent power supplies, lack of training, and mainte- ferent to that projected or to the adaptation options not nance and operational costs (estimated at 16 times that performing as well as expected (Willows and Connell, 2003). of groundwater extraction). There has been mixed suc- Three broad types of adaptation error are recognized: cess for declaring privately owned land in groundwater recharge areas as water reserves with restricted land uses; ˇ Underadaptation ­ which is likely to result from situ- often the restricted rights of affected landowners has ations in which climate change should have been resulted in conflict. Poor access to information regarding an essential component of a decision, but was either available water storage and the impacts of climate varia- ignored or given less weight relative to other factors tions has also made it difficult to establish water policies than it should have. Such situations are likely to result and legislation. in insufficient weight being given to climate change adaptation Proposed future adaptation strategies for Tarawa broadly ˇ Overadaptation ­ which results from the inverse of fall under three themes: capacity strengthening, demand conditions associated with under-adaptation. The im- management and refurbishment of infrastructure and pro- portance of climate change risks is overstated relative tection and supplementation of freshwater resources. Spe- to other factors and greater emphasis than was neces- cifically, these include: sary is placed on adaptation. ˇ Maladaptation ­ in which actions are taken which re- ˇ Establishing a sound institutional basis for the manage- duce the options or ability of decision makers to man- ment of water and sanitation; age the impacts of climate change. ˇ Improving community participation in water and re- lated land management planning to reduce conflicts; Given the uncertain decision-making environment for ˇ Increasing capacity to analyze and predict extreme climate change adaptation, it is necessary to balance the water events (especially droughts); risks of under and over-adaptation. In the first instance, `no ˇ Improving knowledge of available water resources, regrets' adaptations, which make sense even in the absence including their quality and demand upon them. of experienced climatic change, should be deployed. Be- ˇ Improving water conservation and demand manage- yond that, the level of investment in adaptation will depend ment strategies and reduce leakage from water supply on the resources available and the severity of consequences infrastructure; and likelihood of various climate change impacts. Where ˇ Protecting groundwater source areas from contamina- potential impacts are severe and resources are available, the tion. risk and implications of underadaptation may be too great to bear. White et al. (2007) conclude that improving and sharing knowledge about climate and water resources is an essen- The concept of maladaptation should also be extended to tial element of adaptation and that this knowledge must be include actions that either conflict with other social, eco- communicated in a way that is consistent with traditional nomic, resource management or environmental objectives oral forms of knowledge transfer. They also highlight the or add further pressure to the global climate system by sig- need for investment in regional solutions, local engage- nificantly increasing greenhouse gas emissions. Examples ment and long-term partnerships. could include: 43 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options ˇ clearing native vegetation to increase recharge to in vulnerability with the suite of applicable adaptations. The aquifers ­ this would result in emissions of greenhouse latter are those which are practically implementable and gases and loss of biodiversity and could lead to erosion either institutionally compatible or not outside the bounds and increased flash-flood risk; of realistic institutional reform. Economic efficiency would ˇ increasing water availability through treatment of low most likely be incorporated within an assessment against quality water using processes that expensive and en- economic objectives. Flexibility is relevant, but is not explic- ergy intensive processes which will be operated using itly considered in the evaluation. Adaptation options would coal-fired power stations; only be selected if they could be `adapted' to local circum- ˇ introduction of market-based measures for water stances. resource management that impoverish, or further im- poverish small irrigation producers. 3.5.3 Barrierstointroductionof adaptations 3.5.2 Evaluationofadaptationoptions Many of the adaptations described in this section are based The need to avoid the adaptation decision errors described on experiences of developed nations with experience of in the previous section suggests some form of evaluation climatic and hydrological variability and with robust insti- process prior to implementation. Drawing on work carried tutional arrangements for water resource management. out for the IPCC, Dolan et al. (2001) identified several pos- Under current conditions, many of the adaptation options sibilities, including benefit-cost analysis, cost-effectiveness may not satisfy criteria such as cost, implementability and analysis, risk benefit analysis, multi-objective analysis and institutional compatibility (Dolan et al., 2001) for World Bank multiple criteria evaluation. They also applied a Multiple client countries. Successful introduction would require ex- Criteria Evaluation (MCE) or Multi-Criteria Analysis (MCA) to ternal technical and financial support, as well as institutional evaluate a set of adaptation options applicable to Canadian strengthening and policy reform. The challenges in estab- agriculture. The criteria used included: lishing an appropriate institutional setting for introducing many of the `adaptive capacity' options should not be un- ˇ effectiveness derestimated. ˇ economic efficiency ˇ flexibility ˇ institutional compatibility 3.5.4 Economicconsiderations ˇ farmer implementability Groundwater management is fundamental to the sustain- ˇ independent benefits7 ability of water resources and there are strong environmen- tal, economic and social reasons that justify government The criteria appear to be broadly suited to the evaluation investment in groundwater management and adaptation of adaptations in other economic or social sectors, includ- to climate change. Not least of these is the ability for gov- ing groundwater resource management. However, `farmer ernments to continue to provide water for basic human implementability' would need to be amended to the more needs and groundwater dependent industries such as agri- generic `implementability'. culture. The evaluation anticipated by the vulnerability assessment Across most countries in the world, groundwater is cur- process (described in the larger report) is against criteria rently supplied for free, or at a minimal fee. Without an framed around management and development (or other) income stream, investment by governments in groundwa- objectives for the groundwater system. It is anticipated ter management is not profitable and is thus often poorly that these would have social, economic and environmental dimensions. Effectiveness is determined by a re-run of the 7 Benefits not relating to the contribution to avoiding or reducing overall risk assessment to determine if there is any change risks associated with climate change. 44 Adaptation to Climate Change addressed. Successful management and implementation ˇ Ongoing costs ­ due to (for example) monitoring and of adaptation options will only occur if there is adequate maintenance requirements. financial support. Adaptation options must therefore be ˇ Revenue ­ whether or not the options have a source of assessed against economic objectives that factor any initial income, such as fees for water usage, to enable some and ongoing costs, and available means for financing these. cost recovery. ˇ Local economic conditions ­ this will affect costs for ma- All adaptation options cost money: there is no free or cheap terials and labor, and the degree to which a commu- generic solution that will resolve the current and future nity or country is able to fund the option themselves pressures on groundwater resources globally. But economi- (versus the need to loan money from elsewhere). cally feasible options do exist. In developing nations, low ˇ External financers ­ the availability of financial contribu- cost low technology solutions are likely to be more success- tions and/or loans from external sources, and the con- ful. In some cases, the costs and benefits of an adaptation ditions under which these finances are provided (time option may warrant introducing fees/charges for ground- frame required for pay back, interest rate levels etc). water use, so that an appropriate level of cost recovery is met. The diverse range of managed aquifer recharge (MAR) schemes (see Section 3.4.1) illustrates how the economics The economic feasibility of an adaptation option, or suite of of different adaptation options can vary considerably. Low options, will depend on a number of factors: technology schemes such as surface spreading basins and sand dams are less expensive (about US$10 to US$50 per ˇ Cost of start-up ­ costs associated with the initial phas- ML, ignoring pipeline costs) than, for example, borehole es of implementing an adaptation option, for example, injection methods (in the order of US$100 to US$1,000 per building materials and labor to build a managed aqui- ML). Consequently borehole injection methods are often fer recharge scheme, or human resources, software less viable, particularly for agricultural purposes, although in and computer storage for establishing a groundwater some areas may be suitable for urban and domestic water database. The cost of start-up will depend on the ad- use. This provides an example where the economic feasibil- aptation type, scale, where materials are sourced from, ity is driven not only by cost, but also other considerations local access to expertise, the amount of in-kind contri- such as the scale of the scheme and the end-user of the butions etc. water resource. 45 4. examples of aDapTaTion measures 4.1 introduction adjustment of building codes, implementing domestic water conservation measures, water restrictions), ad- Case studies of adaptation in groundwater resource man- justing livestock numbers to balance demand for and agement to climate change and hydrological variability in availability of fodder from irrigated pastures, and land the United Kingdom, USA and Australia have been prepared. use planning controls to cap local population growth. They illustrate approaches to adaptation to climate risks for ˇ Avoiding risk ­ including through adjustment of agri- groundwater dependent systems in contrasting situations, cultural enterprises to reduce requirement for irriga- but from countries with relatively mature information bases tion, balancing grazing livestock numbers to capacity and institutional arrangements for water resource manage- to provide fodder from limited irrigation and sourcing ment. They provide a useful guide to approaches to adapta- alternative water supplies that are less or not sensitive tion to climate change and hydrological variability and also to climate (e.g. desalination or inter-basin transfer). illustrate some of the challenges involved. The case studies demonstrate a wide range of adaptations 4.2 Case study comparison across many of the types described in sections 3.1 and 3.2. The adaptations are primarily in response to water scarcity Steps from the vulnerability assessment framework (de- and to minimize risks to water quality. Measures identified scribed in the larger report) have been used to compare or implemented in the case studies include: the adaptation case studies and to illustrate commonalities and differences between case study approaches and the ˇ Building adaptive capacity ­ through understanding the vulnerability assessment framework. It is important to note system's exposure and sensitivity to climate risks, conjunc- that the methods used in each of the case studies were not tive water resource planning, establishment of markets based on the vulnerability assessment framework and thus for water, establishing and applying standards for water some elements of the framework are not applicable. use measurement, establishing goals for sustainable levels of water use; increasing end-user engagement in water resource planning and management, separate manage- 4.2.1 Establishingthecontext ment of water for consumptive and environmental uses Table 4.1 outlines the context for the four adaptation case and community education-behavior change campaigns. studies, based broadly on the first step of the vulnerability as- ˇ Modify exposure to risks from climate change and hy- sessment framework. Additional contextual information is pro- drological variability ­ through supply augmentation vided in the case study summaries (Sections 4.3, 4.4 and 4.5). and diversification, conjunctive planning and use of groundwater and surface water resources, managed The water supply systems in each of the case studies are aquifer recharge, deepening groundwater utilization critically dependent on groundwater and all have been ex- bores, protection of source water quality, environmen- posed to drought/climate change in recent years. Combined tal water provision for groundwater dependent ecosys- with growing demand and/or competition for groundwater tems and setting and enforcing caps on water use. from urban and/or rural users, water resource managers ˇ Modify sensitivity to climate change and hydrological in each of the case studies face a declining or potentially variability ­ through improved soil management to declining water supply. In some cases water quality is also increase rainfall infiltration and reduce reliance on ir- under threat. An increasing value on, and legislative require- rigation, improve irrigation scheduling and application ments to protect, the environment have also influenced the techniques, urban water demand management (e.g. way in which groundwater resources are managed. 47 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options table 4.1: Context for the Four adaptation Case studies Case study Australia ­ UK ­ East Anglia USA ­ Oro Valley Gnangara Mound Australia - Hawkesdale Location Eastern England South west USA Western Australia South eastern Australia Planning time- 6-yearly cycle 10-yearly cycle 2030 and beyond Considers climate change impacts frame at 2030 and 2070 Water allocated on a Water allocated on a 12 year timeframe 100 year timeframe Groundwater Chalk limestone & Tertiary sedimentary Superficial (sand) water Port Campbell limestone, Newer system Crag (gravels, sands, (sand, gravel, conglom- table aquifer, plus deep- volcanic basalt, plus deeper con- silts & clays) aquifers erate) aquifer er confined aquifers fined aquifers Groundwater fully Groundwater over-al- Groundwater over-al- Groundwater is used for stock & allocated. Used for located. Sole source for located. Used for urban domestic, dairy and irrigation. irrigation, residential, town water supply. water supply, irrigation, Temperate climate commercial & envi- Semi-arid climate industry & the environ- ronment ment. Insufficient data to know if the System is very sensitive system is fully allocated or not Temperate climate Mediterranean climate to changes in rainfall Plantation forestry in the area Groundwater supports wetland & cave ecosys- tems Stakeholders Irrigators, food in- Residents, Oro Valley Residents, Government, Irrigators, dairy & forestry indus- dustry, Environment Water Utility, Govern- farmers, tourism and tries, stock and domestic users, Agency, residents, ment other industries Government Government Key objectives To meet the future To meet future water To meet future water To ensure groundwater extraction water needs of needs of the Oro Valley demand falls within the `sustainable yield' abstractors without township. of the aquifer+ To protect groundwater damaging the envi- To balance groundwater dependent ecosystems ronment. use with groundwater recharge Success criteria Meet water quality Sustainability thresholds Thresholds for wetland NA (example) guideline criteria for groundwater levels water levels Climate change Historical, current Drought conditions Historical, current Historical, current, 2030 best/ scenarios worst case, 2070 best/worst case Drivers for ad- Water use demand Persistent drought con- Population growth Drought aptation ditions and increased water Changes in the value State Government policy demand society places on Population growth Increasing demand the environment Declining groundwater Declining groundwater levels European Water levels & reduced well Framework Directive production capacity Recent drought Recent drought Environmental values The sustainable yield is the renewable part of the groundwater resource, identified after making allowance for acceptable impacts on us- ers, the surface environment and the resource itself. 48 Examples of Adaptation Measures With the exception of the Hawkesdale case study, future 4.2.2 Identifyingandanalyzingrisk climate change scenarios are not explicitly included in the Table 4.2 summarizes the climate risks identified in each of water resource planning process. Instead, historical climate the case studies and how these risks have been analyzed. and recent drought conditions have been used, assuming Across all case studies, the most significant climate hazards that the latter represents a conservative worst case scenario are reduced rainfall and increased frequency of drought. for the future. There are potential limitations to this ap- Hazards for the groundwater system include reduced proach, as discussed in Section 4.2.6. recharge, groundwater contamination and an increased table 4.2: Case study overview ­ identifying and analyzing risk Case study Australia ­ UK ­ East Anglia USA ­ Oro Valley Gnangara Mound Australia ­ Hawkesdale Climate hazards Warmer wetter winters Reduced rainfall Reduced rainfall Reduced rainfall Warmer drier summers Increase in tempera- Increase in tempera- Increased temperature ture ture Increased frequency of Increased frequency of drought drought and flood More severe drought Increased frequency of drought Climate related Delay in the start of the Reduced groundwater Reduced groundwa- Reduced recharge hazards for the recharge season recharge ter recharge Increased demand for groundwa- groundwater Shorter recharge season Increased demand for Increased demand for ter, due to a shift from dryland to system groundwater groundwater irrigated agriculture Increased vegetation water use Reduced water sup- ply to groundwater Increased water de- dependent ecosys- mand for the public, tems irrigators and the envi- ronment Reduced water quality Pre-existing Time-limited abstrac- Further development Limits on groundwa- Further development of ground- climate risk con- tion licences of groundwater re- ter allocation water resource trols source Cessation conditions Restrictions on when groundwater or groundwater pump- river levels drop below a ing set threshold. Assess conse- Potential consequences Assessment of sustain- Aware of potential Likelihood of reduced groundwa- quences and are identified (e.g. inad- able extraction under consequences for ter recharge modeled for each of likelihood of po- equate water supply for drought conditions water supply system the climate change scenarios. tential climate irrigation, domestic use has been made. Fu- and ecosystems. No assessment of other conse- impacts and the environment). ture climate change Likelihood of conse- quences. However, no formal scenarios were not quences is not docu- assessment has been included. mented. made. Risk rating No risk rating No risk rating No risk rating No risk rating 49 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options demand for water. Each of these is affected by climate, Case studies have not tested identified adaptations against but also by other factors such as land use and population future climate change scenarios, although have considered growth. existing climate (including drought) conditions. If future cli- mate change scenarios include conditions worse than the Pre-existing climate risk controls comprised either (1) fur- recent drought, this approach could result in underadapta- ther development of the groundwater resource to meet tion. Each of the case studies acknowledge that in the face water needs, or (2) limits on groundwater allocation and of future climate change additional adaptations may be abstraction to ensure groundwater levels are maintained, required if water resource managers are to meet their key particularly where these sustain important ecosystems or objectives. Additional options raised include: water trading, provide a critical potable water supply. In all case studies, better conjunctive use of surface water and groundwater, it was acknowledged that these measures alone did not relaxing the development of local groundwater resources form an adequate response to climatic influences and other and relying more on alternative renewable water resources, pressures on the system, particularly in the Oro Valley and and expanding existing approaches such as managed aqui- Gnangara Mound case studies where declining groundwa- fer recharge. ter level trends occur. None of the case studies have documented any analysis of 4.2.4 Stakeholderengagement climate risk. Whilst water resource managers are aware and Stakeholder engagement forms an important component are acting upon the consequences of potential climate risks for all of the case studies. The development and engage- (e.g. inability to meet water needs, decline in ecosystem ment of farmer groups in East Anglia provided a powerful health etc), there is no formal documentation of the likeli- tool for educating community and implementing adapta- hood of these consequences occurring. tion options. It also created an environment for innovation in water use efficiency, and a communication channel for irrigators to be informed so that they in turn can make 4.2.3 Evaluatingandtreatingrisks sound investment decisions. In the Oro Valley, successful Table 4.3 outlines if and how the case studies have docu- stakeholder engagement is critical for the implementation mented processes for evaluating and treating climate risk. of their water conservation program. The case studies do not document any process for prioritiz- In the Gnangara Mound, stakeholders are currently being ing climate risks. Uncertainties associated with climate risks engaged in the development of a sustainability strategy. are also not addressed, with the exception of the Hawkes- This strategy is taking a whole of government approach, in- dale GMA. In this case probability distributions of rainfall volving and liaising with diverse groups, including land use and groundwater recharge were modeled to understand planning, water resources, infrastructure, and biodiversity. the uncertainties in future rainfall and groundwater re- This provides an opportunity to manage water resources in charge (see the larger report for more details). a holistic way. The case studies have identified a number of adaptation In the Hawkesdale GMA, meetings with stakeholders have options, across the types previously described in Section been used to discuss possible climate change scenarios and 4.1. The assessment of these adaptations has not been impacts, and the likely implications for water allocation and documented, but is likely to have included factors such as planning. This assists stakeholders to understand what the the ability to meet desired environmental, social and eco- future may be like and how they as individuals will need nomic outcomes, despite water scarce conditions; ability to adapt. It also provides an opportunity to address stake- to meet legislative and regulatory requirements; financial holder concerns, reducing the likelihood of appeals against viability; acceptable impacts on local economy and stake- allocation decisions. holders, etc. 50 Examples of Adaptation Measures table 4.3: Case study overview ­ evaluating and treating risk Case study UK ­ East Australia ­ Anglia USA ­ Oro Valley Gnangara Mound Australia - Hawkesdale Prioritize risks NA NA NA Uncertainty captured in recharge and assess un- modeling but no formal prioritization certainty of risk Identify adapta- Changes to ab- Further groundwater Supplemental water for Further development of groundwater tion options straction licens- development wetlands resources, including deeper confined ing system Water conservation Re-hydrate cave sys- aquifers Development of Enhanced aquifer tems Groundwater use not currently in- water abstractor recharge Limit groundwater ab- cluded in policy (e.g. plantations) to groups straction be incorporated. Import surface water Investment in Alternate water sources Groundwater allocation limits more efficient Reclaimed water use (wastewater, desali- Manage land use and its impacts on irrigation tech- nated sea water) recharge nologies Enhance recharge Installation of on- via MAR and land use farm reservoirs change Changes to land Demand management management above aquifers Sustainability strategy Assess adapta- Not documented Not documented Not documented Not documented tion options Plan and imple- Options have Some options have Some options have With exception of allocation limits, op- ment adaptation been imple- been implemented been implemented or tions have not been implemented options mented started to be imple- mented 4.2.5 Monitoringandreview ter understand the likely impacts here and monitoring bores have been recommended so real changes can be observed Groundwater levels and chemistry are the most common in the future. In the Oro Valley, groundwater is the only monitoring methods for assessing the impacts of climate source of potable water supply and consequently levels are and other pressures on the groundwater resource. In the closely monitored to ensure security and reliability of supply. Gnangara Mound and East Anglia case studies, measures for surface water (e.g. levels) and ecological health are also included. This allows conjunctive management of both sur- In each of the case studies, water resource managers under- face water and groundwater resources. take periodic reviews of available data, including measure- ments of both the groundwater system (e.g. levels) and Currently there is very limited monitoring of groundwater in external pressures on the system (e.g. climate, population the Hawkesdale Groundwater Management Area, and this growth, metered groundwater use). Review of these data may inhibits the understanding of the resource and the impacts be used to better understand the system and to assess the of any change. Modeling approaches have been used to bet- success of current and/or need for further adaptation. Where 51 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options existing monitoring data cannot be used to measure estab- fidence in the benefits of adaptation or inadequate lished success criteria, additional monitoring may needed. supply of funds. ˇ Behaviors and attitudes ­ community expectation re- garding the quantity of water that will be available for 4.2.6 Observedsuccessfactorsand their use in the future is a significant driver for water barriersforadaptation demand and a barrier for successful implementation of The case studies provide useful insights to both the success water conservation measures. It is difficult for people factors and barriers for implementation of adaptation op- to change their perceptions and behaviors, and to ac- tions. Success factors identified include: cept that things in the future will be different to the past. Effective stakeholder engagement is able to miti- ˇ A multi-faceted approach ­ ensures that outcomes are gate some of these problems. not reliant on a single or small group of measures. In- ˇ Uncertainty ­ there are a number of uncertainties that corporating ways to both enhance supply and reduce impede investment in adaptation options, particularly demand is more effective than looking at either of large capital investments that require confidence in the these approaches in isolation. Capacity building is also future availability of water, future demand, and the eco- a vital component of any multi-faceted approach. nomic environment. It is therefore important to incor- ˇ Collective action ­ to be most effective, adaptation porate uncertainty into the decision making process. measures need to be supported at a range of levels (e.g. local, region, state) and across different groups Factors that may contribute to adaptation decision errors are: (government, community, industry etc). This ensures that decisions are based on a broad knowledge base ˇ Lack of knowledge ­ poor understanding of the signifi- and that the adaptation approach is consistent with cant drivers for current and future change in a ground- everyone working towards common objectives. Collec- water system, including climate change, population tive action also provides a means for sharing risk. growth, cultural, political and economic contexts etc ˇ Strong hierarchy of values ­ clear objectives and a strong can lead to misinformed decisions. The first step to values hierarchy are required to determine an appro- identify adaptation options should be to establish the priate response for restricting or supplementing re- context including identification of all the significant sources that are put under pressure by climate change. drivers. ˇ Adaptations with multiple benefits ­ provides additional ˇ Inadequate scenario planning for the future ­ in three of justification for investment and encourage stakeholder the four case studies, projected climate change was not buy in. explicitly considered in the development of adapta- ˇ Adequate capacity ­ the availability of appropriate tion options. Instead the focus was on meeting water skills, knowledge and time is required to make sound demand under recent drought conditions and using decisions and to implement adaptation options. It is this as a `worst case' basis for the future. This approach also important that local capacity is available (either is fine, as long as these claims are founded by compar- currently or through training and development) for ing recent drought conditions to future climate change the ongoing implementation and maintenance of any projections. However, the Hawkesdale study illustrates adaptation option. that in some cases such an approach may be inad- equate and that rainfall and recharge under worst case Barriers for successful adaptation comprise factors that pre- climate change scenarios may be much less than under vent adoption, or that result in adaptation decision errors. the drought conditions of recent years. If the worst case Factors preventing adoption include: climate change scenario is realized, basing decisions on historical drought data may lead to underadaptation. ˇ Costs ­ inability to justify the level of investment re- ˇ Conflict of interest ­ short term versus long term inter- quired to implement adaptation, due to lack of con- ests, potential conflict of interest by decision makers. 52 Examples of Adaptation Measures ˇ Inadequate evaluation of adaptation options ­ against been managed in England for many decades. An abstrac- economic, social and environmental criteria. Evaluation tion license, issued by the Environment Agency, is required based only on current conditions, not the projected for uses exceeding 20 m3/d. Historically, abstraction licenses future environment. were generally not time-limited, but all new licenses are time-limited normally to 12 years, although with a pre- None of the case studies have used an established frame- sumption of renewal (i.e. priority over new applicants work for assessing vulnerability. In particular the case stud- provided water is available). Most abstraction licenses have ies are lacking in a formal assessment and prioritization of cessation conditions attached which require abstraction to risk. Whilst adaptations may be developed without a vulner- stop immediately if groundwater or river levels drop below ability assessment framework, there are significant benefits a set threshold. Licenses are issued on a first-come first- in doing so: served basis without prioritizing uses, but during droughts, priority for groundwater use is given to maintaining public ˇ It ensures that critical steps are incorporated into the water supply, then environment and finally irrigation. decision making process. ˇ It allows users to analyze the elements of risk and to Groundwaterresourcesandclimate document the assumptions and priorities behind the change risk assessment ˇ A sound understanding and documentation of the Much of East Anglia is underlain by productive aquifers, in issues, objectives and likely risks helps to justify invest- particular by the Cretaceous Chalk and younger Pliocene- ment for adaptation. Pleistocene Crag. Both are generally water table aquifers, although the overlying superficial deposits exert strong ˇ Prompts users to evaluate adaptation options against controls on groundwater flow and groundwater age. The established criteria and objectives, to see if the desired Chalk is the most important aquifer within Great Britain. outcomes will be met and if it is worthy of investment. Groundwater is used for domestic, industrial and com- mercial water supply, irrigation, environmental allocations 4.3 uk case study summary and to support recreation. About 37% of water use is from groundwater. Across UK, only about 150 000 ha of agri- Background cultural land is irrigated, with usage accounting for about The United Kingdom case study (see larger report for full 160 000 ML of water in a `dry' year. The licensed volume of case study) considers the management of groundwater groundwater abstraction for irrigation has declined in the in East Anglia, in eastern England. East Anglia is the most east of England in recent years, although actual use has intensively cultivated arable region in the UK. Groundwater been stable for many years. Despite its small volumetric is widely used for supplemental irrigation, as well as for demand, irrigation is of significant economic importance residential and commercial purposes. While use for irriga- to farmers, growers, and the food industry, improving crop tion has been relatively stable, demand from other uses has yields, quality, consistency and reliability. Competition for been growing. With projected climate change, demand for groundwater is likely to increase in future, reflecting re- irrigation is expected to increase and supply decrease, exac- duced supply due to projected climate change and grow- erbating pressures on resources. ing demand from other sectors, including domestic use and environmental water provision. Groundwatermanagement Long-standing groundwater management legislation has arrangements meant that groundwater uses in East Anglia have been con- Groundwater is managed under the same general arrange- trolled. As a consequence there are no consistent long-term ments as surface water in the UK. Groundwater use has trends in groundwater resource status. Groundwater levels 53 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options are generally controlled by the regional recharge and rise take place at a local level and that surface water and and fall in line with variations in rainfall. Although ground- groundwater resources are managed conjunctively in water resources are stable, assessments have indicated that each water management unit. License trading within there is little groundwater available for further abstraction in management units is now permitted to encourage many groundwater units. better utilization of scarce resources. ˇ Development of Water Abstractor Groups ­ the forma- Climate change is projected to have several direct impacts tion of such groups has empowered farmers to influ- on groundwater in East Anglia. Drier summers and in- ence water policy and participate in resource manage- creased summer and autumn potential evapotranspiration ment decision-making. are projected to delay the wetting up of soils and postpone ˇ Investment in more efficient irrigation technologies commencement of the recharge season. With warming and better irrigation scheduling to reduce demand for conditions, potential evapotranspiration is projected to be water. greater in spring, leading to more rapid drying of soils and ˇ Installation of on-farm reservoirs to capture and store a shortening of the recharge season. Reduced recharge surface flows in winter and provide alternative supplies in response to these factors may be at least partly offset to groundwater to help meet summer demand. by projected wetter conditions during winter, although ˇ Changes to land management to reduce water quality recent work suggests there will be an overall reduction in threats to groundwater resources from excessive use groundwater recharge. Warmer and drier conditions during and leaching of nitrogenous fertilizers. summer are likely to increase demand from all of the cur- rent uses. The need to reduce climate-induced stresses on vulnerable aquatic or groundwater-dependent terrestrial Discussion ecosystems could further reduce the availability of ground- While climate change is not a significant driver, a range of water for use in irrigated agriculture. potential adaptations to water scarcity have been imple- mented in East Anglia. By helping to build the adaptive capacity of the irrigation sector and helping to reduce de- Adaptationtoclimatechangeand mand, they are developing resilience to observed climate hydrologicalvariability variability and projected climate change. The water environment in the UK is heavily controlled, with the European Water Framework Directive the dominant Despite successes in implementation of adaptations, sig- influence. Its objective of achieving Good Ecological Status nificant barriers or limitations exist. The short duration of in all surface water bodies (and Good Status in groundwater abstraction licenses means that confidence among irriga- bodies) by 2015 and beyond, and short-term economic tors may be insufficient for the major capital investments pressures faced by agriculture, mean that few irrigators in to increase resilience. The combination of short-term eastern England are deliberately or specifically adapting to economic uncertainties surrounding agricultural produc- projected climate change. They and the abstraction licens- tion, limited financial support from Regional Development ing authority are adapting to water scarcity though in ways Agencies and uncertainty over water availability also are that should help them cope with the projected impacts of barriers. climate change. Adaptations include: The sharing of water resources through water trading has ˇ Changes to the abstraction licensing system that en- yet to develop in the UK, even though legislation allows it. able adaptive management - a 6-yearly water resource This reflects in part uncertainty over the processes involved planning cycle has been introduced to help ensure and the greater simplicity of existing informal practices of sustainable levels of abstraction are maintained in renting or purchasing land with abstraction licenses that the face of changing supply conditions. Manage- are used by farmers. The potential for water trading is large, ment arrangements ensure that abstraction decisions as many abstraction licenses are never used and more are 54 Examples of Adaptation Measures only partially used. Trading would allow water to be used Population growth is placing increasing demands on the where most needed. The danger however is that in areas groundwater supply. Ten years of persistent drought and where water resources are already under pressure, the re- the accompanying reduction in recharge to groundwater activation of sleeper or unused license could cause an even have caused water levels in the sole source aquifer to de- greater conflict between the environment on the one side cline significantly. The drop in water levels and a reduction and the abstractors on the other. in well production capacity in some wells caused the Town to investigate groundwater availability and develop altered Whilst the adaptation measures that have been discussed approaches to groundwater management. have increased the efficiency of utilization of groundwater, they have not fully exploited the abstraction opportuni- ties afforded by better conjunctive use of surface and Groundwatermanagement groundwater. It is suggested that adapting conjunctive use arrangements guidelines to make more use of the higher river flows in the A water right is required in the State of Arizona to withdraw "wetter" winters and saving groundwater for when rivers are surface water or groundwater. Groundwater rights within low; and/or making better use of the difference in timing the U.S. are managed individually by each of the fifty states. between high irrigation demand and low groundwater lev- In Arizona, water rights are based on the doctrine of prior els might further increase resilience. appropriation, which simply stated is a right of "first in time, first in right". A water right is generally required for indus- The adaptation options already implemented are unlikely trial, irrigation, and municipal needs. Most domestic uses to be sufficient to cope with the range of future water are exempt from obtaining a water right. resource outcomes anticipated by climate and socio-eco- nomic change. Given the likely increasing future demand The transition from agricultural to urban population base for a diminishing resource, it is likely that further adaptation is occurring in the region's major metropolitan areas, will be required, which might include further restriction Tucson and Phoenix. This transition would not have been of irrigation to the highest-value crops or a move to non- possible without allowing the transfer of water rights from irrigated agriculture or livestock. agricultural (irrigation) to potable use. Many of the water rights for agriculture are very senior rights and typically the water rights are sold with the land. In these major 4.4 usa case study summary metropolitan areas, groundwater is fully appropriated. So development is dependent on having the right to use the Background water. The case study (see larger report for full case study) con- siders improved management of groundwater supply to In 1980, the State of Arizona adopted a Groundwater Man- meet the future needs of residents of the township of Oro agement Act that includes the Assured Water Supply (AWS) Valley (the Town) in the semi-arid south-west of the USA. program. The AWS program requires water service provid- Challenges associated with persistent drought conditions, ers, including municipalities and developments located in which may be attributed to global climate change, are be- unincorporated portions of the counties, to demonstrate ing incorporated into long-term water resource manage- that an AWS will be physically, legally, and continuously ment planning by the Town. available for the next 100 years before the developer can record plats or sell parcels of land. The provider must Recent climate changes have resulted in decreased pre- prove that a 100-year groundwater supply is available by cipitation and surface runoff causing a significant drop in either satisfying the requirements to obtain a Certificate recharge to groundwater throughout south-western USA. of Assured Water Supply or by a written commitment of a Local groundwater resources have historically been the water service provider with a Designation of Assured Wa- principal source of potable water supplies of the Town. ter Supply. Managed by the Arizona Department of Water 55 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options Resources (ADWR), this program has created a process that Adaptationtoclimatechangeand requires a study be completed to ensure that a long-term hydrologicalvariability supply exists, that each successive AWS designation does Adapting to uncertain changes in supply caused by multi- not adversely impact pre-existing rights, and that recharge ple pressures, including climate change, has become a high to the aquifer is considered (although potential impacts of priority. The impacts to groundwater caused by climate climate change are not considered). changes include declining water levels or other stresses that are not easily predictable and uncertain. Groundwaterresourcesandclimate change The use of groundwater by the Town is controlled by water rights (groundwater is fully appropriated) and The Town of Oro Valley is located within the Basin and groundwater regulations that affect Oro Valley and other Range geographic province, which generally consists water providers in the region that tap the same aquifer. of north to south trending basins separated by north to Groundwater pumping has increased in the last 10 years south trending mountain ranges. The basin is about 8 km at a faster rate than is being recharged, and groundwater in width in the Oro Valley area, but extends to about 29 km levels are dropping. Model predictions indicate increased north to the Falcon Valley area. The stream channel consists pumping will not sustain groundwater availability. There- of basin-fill deposits, comprising granular sands and gravels fore the Town has developed, and is beginning to imple- that are highly permeable, readily accept streamflow infil- ment, multiple strategies that include water conservation, tration, and therefore are optimum as a catchment area for use of reclaimed water in lieu of potable water, improved recharge. storm water capture to enhance groundwater recharge, better engineered wells to improve capture and manage Recharge to the aquifer system in the area occurs from groundwater in a sustainable manner, shift water be- infiltration along adjacent mountain fronts, underflow tween sectors (agriculture to urban), and import surface from north-eastern parts of the Oro Valley area, and stream water sources to supplement and reduce demand on channel recharge along ephemeral drainage lines. Based groundwater. on estimated recharge rates, average rates of groundwater recharge at the mountain fronts and stream channels in the The Town has taken significant steps to secure new water Oro Valley vicinity are estimated at about 4.7 to 9.6 GL/y. supply sources to alleviate the effects of over-drafting the Based on this range, average annual local groundwater re- groundwater aquifer system and impacts due to climate charge totals about 7.2 GL. The quantity of annual ground- change. Current and future water resource planning and water recharge is consequently reduced by the affects of management adaptations include: drought. ˇ groundwater development based on sustainability Results of the study imply that there is an exponential criteria; rather than linear relationship between recharge and ˇ augment water supplies by importing reclaimed water precipitation. As a result, mountain front recharge is and treated central Arizona project water; believed to be sensitive to a relatively small reduction ˇ implementation of water conservation policies; in precipitation. After 1995, when the average annual ˇ enhance local groundwater recharge, including precipitation rate decreased to about 25 cm/y, it is antici- through improved storm water management. pated that a significant reduction in recharge will occur. It is conjectured that stream channel recharge is similarly All of these options consider technical, financial, legal, po- reduced as well. Actual reduction of natural groundwater litical, institutional, and environmental impacts. The Town recharge under persistent drought conditions remains is adopting impact fees to finance and implement current unclear based on available data, but is considered to be and future strategies. significant. 56 Examples of Adaptation Measures 4.5 australian case study summaries The Gnangara Mound is an area of sandy aquifer material that is open to direct groundwater recharge, located around Two contrasting groundwater management case studies and to the North of the city of Perth, Western Australia. It have been documented for Australia, the first relating to covers an area of approximately 2,200 km2. The aquifer is the Gnangara Mound in Western Australia and the sec- underlain by shallow exposed sands and is largely depen- ond to the Hawkesdale Groundwater Management Area dent on rainfall recharge for water supply. (GMA) in south-western Victoria. The Gnangara Mound is an important groundwater resource for the city of Perth, however it also supports groundwater dependent eco- Groundwater management arrangements systems with very high conservation value. The Hawkes- The Department of Water is the manager of the State's dale GMA is in a largely rural region, with groundwater water resources. It has the responsibility for planning and primarily used for irrigation and on-farm domestic and managing groundwater use on the Gnangara Mound for livestock use. the benefit of the community. This involves identifying and protecting important groundwater dependent ecosystems The case studies also illustrate differences in groundwater and managing private and public water supply abstrac- management arrangements between jurisdictions. Under tion to protect those systems. The Department regulates Australia's constitution, groundwater management is the the Water Corporation (the water retailer) and private use responsibility of State or Territory governments. This means through licensing and monitors impacts on water levels that whilst there is general agreement between the differ- and ecosystems. ent jurisdictions, individual governments have somewhat differing approaches to water allocation and planning. Con- Western Australia's Integrated Water Supply System (IWSS) is sistent features of the approach include state ownership the key integrated system which provides potable water for of water, with allocation of rights to access and use water Perth and surrounding areas. This system has relies heavily being controlled by government. Allocation policies vary in on water pumped from the Gnangara system. Approxi- detail but are all aligned on an approach to the sustainable mately 45% of groundwater pumped from the Gnangara allocation of groundwater in keeping with the concept of system is for the IWSS. Current management criteria also safe yield. Generally groundwater allocation for consump- set out private groundwater allocation quotas of 60.6 GL/y tive use will only be permitted where the resource can from the Gnangara Mound. be maintained sustainably over the long term. Individual jurisdictions differ in the definitions of sustainability and in Groundwater resources and climate change the legislative mechanisms that are available to manage allocation. The Gnangara Mound is a term used to describe an inter- connected groundwater system that consists of three par- tially connected aquifers, the superficial (water table) aqui- 4.5.1 ManagementoftheGnangara fer (the Gnangara Mound proper), the Leederville aquifer Mound,WesternAustralia and the Yarragadee aquifers. The latter two are deeper and generally confined aquifers that extend north and south of Background the superficial aquifer extent. The aquifers of the Gnangara The Gnangara Mound case study considers the situation system represent one of the largest sources of potable wa- of a large shallow aquifer which has many ecological, so- ter in south-western Australia. cial and economic demands. This aquifer and associated groundwater dependent ecosystems are highly sensitive to While abstraction of groundwater occurs across the system, relatively small changes in storage volume. Management of impacts of abstraction predominantly manifest on the water level is the key issue, given the range of interactions mound, that is, upon the shallow aquifer units. It is these with the surface of the aquifer. shallow units that are most affected by changes in rainfall 57 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options and hence by climate variability and change. The aquifer tion or the overall decline in the vicinity of wetlands. In system is finely balanced and the response to changes some areas, superficial bores have been switched off in in climate is likely to be felt in the short rather than long an effort to meet wetland water level criteria. term, impacting for example a number of groundwater ˇ Assessing managed aquifer recharge for the area ­ one dependent wetlands that are already affected by recent dry project has trialed injection of reclaimed water (i.e. weather. treated municipal effluent) into the deeper (Leeder- ville) aquifer as a pilot to prove the feasibility of future Groundwater levels within the Gnangara Mound have been injections. A trial is also planned for the superficial trending downwards for the last 30 years. The centre of the aquifer. decline is largely within the central mound region where ˇ Exploring alternative land uses after existing pine plan- drawdown up to 6 m has occurred over this period. Typical- tations are harvested ­ land use may be changed to ly drawdown is in the range of 1 to 2 m. This coincides with enhance rainfall recharge in key areas that are currently a general trend of declining annual rainfall across the south in recharge deficit. west of Western Australia. Abstraction and land use impacts ˇ Establishing a horticultural precinct using treated on recharge are also implicated in declining groundwater wastewater rather than potentially potable water from levels. Climate change projections for the region are for the Gnangara Mound. further reductions in rainfall, with likely consequent impacts ˇ Changing land management (e.g. burning of Banksia on recharge. woodlands) to increase recharge and maintain biodi- versity values. ˇ Revising groundwater allocation to public and private Adaptation to climate change and hydrological water supplies. variability ˇ Development of the Gnangara Sustainability Strategy Several measures have been introduced or are consider- (GSS)8, a whole of government approach to ensure the ation to enable the Gnangara system to adapt to experi- sustainable use of water for drinking and commercial enced climate change. Measures are directed at protecting purposes and to protect the environment. This strategy important groundwater dependent ecosystems and main- considers both water and land use impacts on the taining supplies for consumptive uses. Adaptations identi- groundwater resource. fied include: The major constraint on adaptation to changed climate ˇ Wetland supplementation ­ in which water is harvest- conditions in the Gnangara Mound is the expectation of ed from other locations and used to maintain wetland communities that water will always be available in the same levels and ecological values. Two wetlands are cur- quantities for consumptive use. In some cases lower water rently supplemented on the Gnangara Mound, using use activities are considered but in most of the examples, water pumped from the shallow superficial and deeper alternate sources of water are used to substitute for existing Leederville aquifers. groundwater. This brings with it increased costs and low- ˇ Cave system rehydration ­ during summer (when ered certainty of supply. In some cases lower quality water groundwater levels are lowest) re-hydration of a lime- may need to be used. stone caves system has been achieved by pumping water from a lake or from groundwater bores and us- As parts of Perth's metropolitan supply is now from de- ing this to enhance recharge in the vicinity of caves. salinated sea water, there is an element of substitution of The increased recharge re-hydrates the caves and, groundwater for "manufactured" water. This is an example by maintaining the end of summer levels, ecosystem where the ecological value of wetlands that were ground- function is supported. ˇ Limiting groundwater abstraction ­ licensed pumping is tightly controlled to limit the inter-annual fluctua- 8 http://portal.water.wa.gov.au/portal/page/portal/gss 58 Examples of Adaptation Measures water fed is considered high enough to ensure that they are There is no groundwater monitoring of the key Port Camp- supplied by any available water. bell Limestone aquifer within the Hawkesdale GMA. Anec- dotal evidence is provided by local groundwater users that suggests groundwater has been declining significantly for 4.5.2 HawkesdaleGroundwater the past 5 years or so. This is consistent with a prolonged ManagementArea,Victoria spell of relative dry conditions, which may reflect early signs of human-induced climate change. Background The Hawkesdale case study is also for a large volume aquifer Worst case climate change projections for the Hawkesdale system, but one in which recharge and use are currently GMA are for significantly less rainfall and recharge than has considered to be approximately in balance. However this been experienced in the most recent (relatively dry) 10 system may move out of balance due to climate change year period. Temperatures are also projected to increase. and would also do so if growing demand for groundwater Groundwater recharge is projected to decline by an even for irrigated agriculture were to be satisfied. larger amount. Groundwater extraction is widespread across the Hawkes- dale GMA. Approximately 2,300 bores are registered as Adaptation to climate change and hydrological possible extraction bores. Most are registered for stock and variability domestic use, with some used in dairies and for irrigation of Low rainfall over the past decade has resulted in several pastures and fodder crops. adaptive responses already being implemented by local groundwater users. These have primarily taken the form of changes in agricultural enterprise, although more direct Groundwater management arrangements measures have also been developed. Adaptations have The Victorian Government, through its water policy included: statement, Our Water Our Future, has made the commit- ment of bringing all the state's water resources under a ˇ Reducing the stocking rates and herd sizes for given sustainable water allocation regime. For groundwater, properties to match the available feed (that can be this means ensuring that all extraction falls within limits produced without irrigation) to the grazing pressure. defined by the `sustainable yield' of the aquifer. The sus- ˇ Introduce irrigation of fodder crops or pastures into tainable yield is the renewable part of the groundwater the enterprise to reduce reliance on rainfall. As this is resource, identified after making allowance for accept- likely to put considerable pressure on groundwater able impacts on users, the surface environment and the resources this approach has not be favored by the wa- resource itself. ter managers to date. ˇ Restrictions on the volume of licensed groundwater allocations offered to the public, through the relevant Groundwater resources and climate change government agency reducing the availability of water The Hawkesdale GMA covers an area of approximately licenses. 1400 km2. The Newer Volcanic Basalt (NVB), Port Campbell ˇ Re-drilling and deepening bores which dry up as a re- Limestone (PCL), Clifton Formation and Dilwyn Formation sult of reduced water levels. form the significant aquifers in the Hawkesdale GMA. Over ˇ Targeting deeper aquifers which are confined and not much of the Hawkesdale GMA, the Narrawaturk Marl and as affected by direct recharge reduction. Gellibrand Marl are considered aquitards that are believed to effectively hydraulically separate the Clifton Formation Key barriers to adaptation are around the ability to develop Aquifer from the underlying Dilwyn Formation Aquifer and profitable farm enterprises that can operate in a reduced the overlying PCL Aquifer respectively. rain environment, or at best a reduced security of rainfall. 59 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options The key adaptive changes for this area are in policy respons- estry plantations that have been established in parts of es to water allocation, including: the GMA over the last decade. Currently the relevant State government department is considering policy ˇ groundwater allocation limits ­ new (lower) limits responses to water use by plantations. will need to be set in light of the likely reduction in ˇ acknowledging the role of land use ­ land use dic- available recharge. As with the Gnangara Mound case tates the pattern of recharge for the Hawkesdale study, this area is likely to see reductions in recharge area. Changes in land use, such as forestry planta- resulting from climate change; tions and/or cropping and/or irrigation will signifi- ˇ incorporation of uses of groundwater that have not so cantly change the recharge pattern. This in turn will far been incorporated ­ in this area there is a potential have implications for recharge and hence the avail- for significant water use by plants, especially from for- able resources. 60 5. ConClusion Compared to surface water, groundwater is much more trusion to coastal aquifers, contraction of freshwater lenses compatible with a highly variable and changing cli- on small islands, and increased demand. Groundwater can mate. Aquifers have the capacity to store large volumes of also be affected by non-climatic drivers, such as population water and are naturally buffered against seasonal changes growth, food demand and land use change. Active consid- in temperature and rainfall. They provide a significant op- eration of both climatic and non-climatic risks in groundwa- portunity to store excess water during high rainfall periods, ter management is vital. to reduce evaporative losses and to protect water quality. Effective, long term adaptation to climate change and Groundwater is a critical component of adapting to hydro- hydrologic variability requires measures which protect logic variability and climate change. Groundwater options or enhance groundwater recharge and manage water for enhancing the reliability of water supply for domestic, demand. Adaptation to climate change can't be separated industrial, livestock watering and irrigation include (but are from actions to improve management and governance not exclusive to): of water reserves (e.g. education and training, information resources, research and development, governance and in- ˇ Integrating the management of surface water and stitutions). groundwater resources ­ including conjunctive use of both groundwater and surface water to meet water Adaptation needs to be informed by an understand- demand. Integrated management aims to ensure that ing of the local context, and of the dominant drivers the use of one water resource does not adversely im- (and their projected impact) on groundwater resources pact on the other. It involves making decisions based in the future. Adaptations must be carefully assessed to on impacts for the whole hydrologic cycle. ensure investment in responses to climate change and ˇ Managing aquifer recharge (MAR) ­ including build- hydrological variability is proportional to risk and that they ing infrastructure and/or modifying the landscape to do not inappropriately conflict with other social, economic, intentionally enhance groundwater recharge. MAR is resource management or environmental objectives. Ad- among the most promising adaptation opportunities aptations should not add further pressures on the global for developing countries. It has several potential ben- climate system by significantly increasing greenhouse gas efits, including storing water for future use, stabilizing emissions. or recovering groundwater levels in over-exploited aquifers, reducing evaporative losses, managing saline Adaptation options need to be economically viable. In intrusion or land subsidence, and enabling reuse of some cases the cost and benefits of an adaptation option waste or storm water. may warrant introducing fees/charges for groundwater ˇ Land use change ­ changing land use may provide use, so that an appropriate level of cost recovery is met. An an opportunity to reduce groundwater losses from economic assessment of adaptation options should fac- evapotranspiration, to enhance recharge, and to tor any initial and ongoing costs, and means for financing improve groundwater quality. Changes in land use these. It must also take into account the local economic should not result in adverse impacts to other parts of environment, which can vary significantly between and the environment. within nations. Groundwater is also vulnerable to climate change and In many cases, adaptations to reduce the vulner- hydrological variability. Potential climate risks for ground- ability of groundwater dependent systems climatic water include reduced groundwater recharge, sea water in- pressures are the same as those required to address 61 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options non-climatic pressures, such as over-allocation or over- Successful examples of groundwater adaptation to cli- use of groundwater. Such `no regrets' adaptations can be mate change and hydrologic variability exist in both de- implemented immediately in areas where water resources veloped and developing nations. A list of available adapta- are already stressed, regardless of concerns about the un- tion options is included in Section 3 of this report. Summa- certainty of climate change projections and assessments of ries of adaptation case studies from three developed nations impact on groundwater and surface water resources. (England, America and Australia) are provided in Section 4. 62 6. reCommenDaTions To improve the capacity for and uptake of groundwater ad- ment should identify areas of current water stress aptation, the following recommendations are made: (i.e. need), water availability (e.g. excess wet sea- son surface flows, treated waste water), potential 1. Support adaptation case studies from developing storage, and the likelihood that groundwater qual- nations ­ adaptation case studies from three devel- ity will be suitable for the required use/s. oped nations were reviewed in the current report. As If MAR is deemed viable, subsequent tasks part of the global groundwater governance project should include: and the Bank's sector analysis on groundwater gover- ˇ Identification and prioritization of water nance project, a series of case studies and evaluations stressed areas, particularly focusing on areas should be prepared for developing countries. Possible of current or foreseeable shortages in drink- case study countries could include: Peru, India, Kenya, ing water supply. Mexico, Morocco, Tunisia, South Africa, Tanzania and ˇ Mapping of MAR potential within the identi- Yemen. Transboundary aquifers might also be consid- fied priority areas. If possible, this should be ered, potentially including: undertaken at a 1:100,000 to 1:250,000 scale. ˇ the Nubian sandstone aquifer system ­ this aqui- This will help prioritize areas for site specific fer is located in north-eastern Africa and spans the investigation and demonstration projects. political boundaries of four countries: Chad, Egypt, Suggested criteria for mapping MAR poten- Libya and Sudan; tial are summarized in Section 3.4.1. ˇ aquifers that span across the fourteen countries ˇ Identification of institutions that may take in the South African Development Community responsibility for regulation, licensing and (SADC) monitoring of MAR schemes These case studies would provide guidance to ˇ Identification of potentially suitable types of water resource managers in similar settings on improv- MAR, mindful that in developing countries ing groundwater governance and conceptualizing and the most successful, low risk MAR schemes implementing adaptation programs. As a minimum are likely to be of simple technology and low the case studies should focus on examples of MAR, cost. Examples of different MAR schemes are improved management of groundwater storages, con- provided in Section 3.4.1. junctive planning and management of groundwater Any planning for MAR should be coupled with and surface water and reform of water governance. demand management strategies. The case studies should cover a range of biophysi- ˇ Capacity building in groundwater management cal and institutional settings and be representative and planning. This may include activities such as of different kinds of experienced climate change or groundwater resource assessments to better un- climate risk impact. derstand the resource, establishing and populat- 2. Promote groundwater management and develop- ing groundwater databases, increasing the level of ment opportunities ­ identify and integrate oppor- hydrogeological expertise by establishing or im- tunities to manage and develop groundwater in future proving accessibility to groundwater training insti- water sector programs to improve the reliability of tutions, a manual for groundwater management water supply. This may include supporting: to outline minimum good practice standards etc. ˇ Assessments of climate vulnerability. ˇ More integrated management of water resources. ˇ Assessment of the suitability of MAR ­ to deter- This may include conjunctive water use and as- mine the potential viability for MAR. This assess- sessing the impacts of existing or proposed infra- 63 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options structure to identify any potential inefficiencies or ˇ Groundwater Resources Assessment under the adverse impacts that may be treated to achieve Pressures of Humanity and Climate Change optimal use of water resources. (GRAPHIC) ­ the GRAPHIC project is hosted by IHP 3. Disseminate knowledge ­ Information from this re- UNESCO, IGRAC and GWSP and focuses on under- port and developing country case studies should be standing the impacts of climate change and other disseminated to World Bank staff as part of the overall pressures for groundwater, globally; sector analysis on Climate Change and Water. ˇ International Association of Hydrogeologists (IAH), 4. Collaborate with programs and partner agencies and with specialized knowledge ­ including: ˇ International Groundwater Resource Assessment Centre (IGRAC) 64 7. glossary of Terms (Source: Bates et al, 2008, except where noted) Climate change Climate change refers to a change in the state of the cli- adaptation mate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties, Initiatives and measures to reduce the vulnerability of natu- and that persists for an extended period, typically decades ral and human systems against actual or expected climate or longer. Climate change may be due to natural internal change effects. Various types of adaptation exist, e.g. antici- processes or external forcings, or to persistent anthropo- patory and reactive, private and public, and autonomous genic changes in the composition of the atmosphere or in and planned. Examples are raising river or coastal dikes, the land use. Note that the United Nations Framework Conven- substitution of more temperature-shock resistant plants for tion on Climate Change (UNFCCC), in its Article 1, defines sensitive ones, etc. climate change as: a change of climate which is attributed directly or indirectly to human activity that alters the com- position of the global atmosphere and which is in addition adaptive capacity to natural climate variability observed over comparable time periods'. The UNFCCC thus makes a distinction be- The whole of capabilities, resources and institutions of a tween climate change attributable to human activities al- country or region to implement effective adaptation mea- tering the atmospheric composition, and climate variability sures. attributable to natural causes. aquifer Climate model A rock formation, group of rock formations, or part of a rock A numerical representation of the climate system based formation that combines sufficient permeable material to on the physical, chemical and biological properties of its yield economical quantities of water to wells and springs. components, their interactions and feedback processes, and accounting for all or some of its known properties. The climate system can be represented by models of varying Climate complexity, that is, for any one component or combination of components a spectrum or hierarchy of models can be Climate in a narrow sense is usually defined as the average identified, differing in such aspects as the number of spa- weather, or more rigorously, as the statistical description tial dimensions, the extent to which physical, chemical or in terms of the mean and variability of relevant quantities biological processes are explicitly represented, or the level over a period of time ranging from months to thousands at which empirical parameterisations are involved. Coupled or millions of years. The classical period for averaging these Atmosphere-Ocean General Circulation Models (AOGCMs) variables is 30 years, as defined by the World Meteorological provide a representation of the climate system that is near Organization. The relevant quantities are most often sur- the most comprehensive end of the spectrum currently face variables such as temperature, precipitation and wind. available. There is an evolution towards more complex Climate in a wider sense is the state, including a statistical models with interactive chemistry and biology. Climate description, of the climate system. models are applied as a research tool to study and simulate 65 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options the climate, and for operational purposes, including month- Climate variability ly, seasonal and interannual climate predictions. Climate variability refers to variations in the mean state and other statistics (such as standard deviations, the oc- Climate projection currence of extremes, etc.) of the climate on all spatial and temporal scales beyond that of individual weather events. A projection of the response of the climate system to emis- Variability may be due to natural internal processes within sions or concentration scenarios of greenhouse gases and the climate system (internal variability), or to variations in aerosols, or radiative forcing scenarios, often based upon natural or anthropogenic external forcing (external vari- simulations by climate models. Climate projections are ability). distinguished from climate predictions in order to empha- size that climate projections depend upon the emission/ concentration/radiative forcing scenario used, which are Confidence based on assumptions concerning, for example, future so- cioeconomic and technological developments that may or As defined by the IPCC, the degree of confidence in being may not be realised and are therefore subject to substantial correct is described as follows: uncertainty. Very high confidence At least 9 out of 10 chance of being correct Climate scenario High confidence About 8 out of 10 chance A plausible and often simplified representation of the future climate, based on an internally consistent set of climato- Medium confidence About 5 out of 10 chance logical relationships that has been constructed for explicit use in investigating the potential consequences of anthro- Low confidence About 2 out of 10 chance pogenic climate change, often serving as input to impact models. Climate projections often serve as the raw material Very low confidence Less than a 1 out of 10 chance for constructing climate scenarios, but climate scenarios usually require additional information such as about the observed current climate. A climate change scenario is the Coping range difference between a climate scenario and the current cli- mate. The range within which a system has the capacity to cope with some level of variability (in this case to climate or hy- drology) without impairment. Climate system The climate system is the highly complex system consist- Detection and attribution ing of five major components: the atmosphere, the hydro- sphere, the cryosphere, the land surface and the biosphere, Climate varies continually on all time scales. Detection of and the interactions between them. The climate system climate change is the process of demonstrating that climate evolves in time under the influence of its own internal dy- has changed in some defined statistical sense, without namics and because of external forcings such as volcanic providing a reason for that change. Attribution of causes of eruptions, solar variations and anthropogenic forcings such climate change is the process of establishing the most likely as the changing composition of the atmosphere and land- causes for the detected change with some defined level of use change. confidence. 66 Glossary of Terms Downscaling uncertainty that is possible with traditional multi-model ensembles. Downscaling is a method that derives local-to regional- scale (10 to 100km) information from larger-scale models or data analyses. Two main methods are distinguished: dy- exposure namical downscaling and empirical/statistical downscaling. The dynamical method uses the output of regional climate In the context of this report, exposure refers to groundwater models, global models with variable spatial resolution or dependent systems being subjected to adverse affects of high-resolution global models. The empirical/statistical climate change and hydrologic variability. methods develop statistical relationships that link the large- scale atmospheric variables with local/regional climate variables. In all cases, the quality of the downscaled product evapotranspiration depends on the quality of the driving model. Loss of water to the atmosphere via direct evaporation or transpiration by vegetation. emissions scenario A plausible representation of the future development of flexibility emissions of substances that are potentially radiatively ac- tive (e.g., greenhouse gases, aerosols), based on a coherent The flexibility of a system refers to its ability to adapt to a and internally consistent set of assumptions about driving wide range of operating conditions through relatively mod- forces (such as demographic and socioeconomic develop- est and inexpensive levels of redesign, refitting or reopera- ment, technological change) and their key relationships. tion (Hashimoto, T. et al., 1982a). Concentration scenarios, derived from emission scenarios, are used as input to a climate model to compute climate projections. In IPCC (1992) a set of emission scenarios was general Circulation model presented which were used as a basis for the climate projec- tions in IPCC (1996). These emission scenarios are referred to See Climate model. as the IS92 scenarios. In the IPCC Special Report on Emission Scenarios (Nakienovi and Swart, 2000) new emission sce- narios, the so-called SRES scenarios, were published. greenhouse effect Greenhouse gases effectively absorb thermal infrared ra- ensemble diation, emitted by the Earth's surface, by the atmosphere itself due to the same gases, and by clouds. Atmospheric A group of parallel and model simulations used for climate radiation is emitted to all sides, including downward to the projections. Variation of the results across the ensemble Earth's surface. Thus greenhouse gases trap heat within the members gives an estimate of uncertainty. Ensembles surface troposphere system. This is called the greenhouse made with the same model but different initial conditions effect. Thermal infrared radiation in the troposphere is only characterise the uncertainty associated with internal strongly coupled to the temperature of the atmosphere at climate variability, whereas multi-model ensembles includ- the altitude at which it is emitted. In the troposphere, the ing simulations by several models also include the impact temperature generally decreases with height. Effectively, in- of model differences. Perturbed-parameter ensembles, in frared radiation emitted to space originates from an altitude which model parameters are varied in a systematic man- with a temperature of, on average, ­19°C, in balance with ner, aim to produce a more objective estimate of modelling the net incoming solar radiation, whereas the Earth's surface 67 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options is kept at a much higher temperature of, on average, +14°C. groundwater discharge An increase in the concentration of greenhouse gases leads to an increased infrared opacity of the atmosphere, and The process by which water is lost from groundwater, therefore to an effective radiation into space from a higher including evapotranspiration, flow to streams, springs, wet- altitude at a lower temperature. This causes a radiative forc- lands and oceans, and pumping from wells. ing that leads to an enhancement of the greenhouse effect, the so-called enhanced greenhouse effect. groundwater management greenhouse gas (ghg) The management of groundwater resources to meet estab- lished objectives for the water resource. Example objectives Greenhouse gases are those gaseous constituents of the include: ensuring availability of the groundwater resource atmosphere, both natural and anthropogenic, that absorb into the future, meeting environmental water requirements, and emit radiation at specific wavelengths within the spec- meeting water quality criteria to be able to provide potable trum of thermal infrared radiation emitted by the Earth's water supply, etc. surface, the atmosphere itself, and by clouds. This property causes the greenhouse effect. Water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and ozone groundwater recharge (O3) are the primary greenhouse gases in the Earth's atmo- sphere. Moreover, there are a number of entirely human- The process by which water from the surface enters the made greenhouse gases in the atmosphere, such as the groundwater system. halocarbons and other chlorine and bromine containing substances, dealt with under the Montreal Protocol. Beside CO2, N2O and CH4, the Kyoto Protocol deals with the green- hydrological cycle house gases sulphur hexafluoride (SF6), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs). The cycle in which water evaporates from the oceans and the land surface, is carried over the Earth in atmospheric cir- culation as water vapour, condensates to form clouds, pre- groundwater cipitates again as rain or snow, is intercepted by trees and vegetation, provides runoff on the land surface, infiltrates The water contained in interconnected pores, gaps or frac- into soils, recharges groundwater, discharges into streams, tures located below the water table in an unconfined aqui- and ultimately, flows out into the oceans, from which it will fer, or in a confined aquifer. eventually evaporate again (AMS, 2000). The various sys- tems involved in the hydrological cycle are usually referred to as hydrological systems. groundwater dependent systems Those systems that rely on groundwater for survival, includ- (Climate change) impacts ing human populations, industries (e.g. agriculture) and ecosystems. The effects of climate change on natural and human sys- tems. Depending on the consideration of adaptation, one can distinguish between potential impacts and residual groundwater development impacts: The abstraction of groundwater for human use. 68 Glossary of Terms ˇ Potential impacts: all impacts that may occur given a pro- palaeoclimate jected change in climate, without considering adaptation. ˇ Residual impacts: the impacts of climate change that Climate for periods prior to the development of measuring would occur after adaptation. instruments, for which only proxy climate records (such as may be determined from tree rings, geology, or ice cores) likelihood are available. As defined by the IPCC, the likelihood of the occurrence/ outcome is described below: projection Virtually certain >99% probability of occurrence A potential future evolution of a quantity or set of quanti- ties, often computed with the aid of a model. Projections Very likely 90 to 99% probability are distinguished from predictions in order to emphasize that projections involve assumptions concerning, for exam- Likely 66 to 90% probability ple, future socioeconomic and technological developments that may or may not be realised, and are therefore subject About as likely as not 33 to 66% probability to substantial uncertainty. Unlikely 10 to 33% probability Very unlikely 1 to 10% probability reliability Exceptionally unlikely <1% probability Reliability is defined as the likelihood that services are deliv- ered (no failure) within a given period, expressed as a prob- ability. High probabilities indicate high reliability (Hashi- managed aquifer recharge moto, T. et al., 1982b). Involves building infrastructure and/or modifying the land- scape to intentionally enhance groundwater recharge. resilience A. The ability of a social or ecological system to absorb mitigation disturbances while retaining the same basic structure and ways of functioning, the capacity for self-organization, and Technological change and substitution that reduce re- the capacity to adapt to stress and change. source inputs and emissions per unit of output. Although several social, economic and technological policies would B. Resiliency is the speed at which the system recovers produce an emission reduction, with respect to Climate from a failure, on average. Shorter recovery periods indicate Change, mitigation means implementing policies to reduce higher resiliency (Hashimoto, T. et al., 1982b). greenhouse gas emissions and enhance sinks. risk no-regrets policy The potential for realization of unwanted, adverse conse- A policy that would generate net social and/or economic quences; usually based on the expected result of the condi- benefits irrespective of whether or not anthropogenic cli- tional probability of the occurrence of the event multiplied mate change occurs. by the consequence of the event, given that it has occurred. 69 Water and Climate Change: Impacts on Groundwater Resources and Adaptation Options What makes a situation risky rather than uncertain is the ment record. Under stationarity, pdf estimation errors are availability of objective estimates of the probability distribu- acknowledged, but have been assumed to be reducible tion. (USACE, 1992) by additional observations, more efficient estimators, or regional or paleohydrologic data. The pdfs, in turn, are used to evaluate and manage risks to water supplies, waterworks, robustness and floodplains (Milly et al., 2008). In a water resources system, robustness refers to the ex- tent to which a system design is able to deliver optimal Threshold or near-optimal levels of service over a range of demand (input) and supply (resource) conditions (Hashimoto, T. et The level of magnitude of a system process at which sud- al., 1982a). den or rapid change occurs. A point or level at which new properties emerge in an ecological, economic or other system, invalidating predictions based on mathematical scenario relationships that apply at lower levels. A plausible and often simplified description of how the future may develop, based on a coherent and internally uncertainty consistent set of assumptions about driving forces and key relationships. Scenarios may be derived from projections, A. An expression of the degree to which a value (e.g., the but are often based on additional information from other future state of the climate system) is unknown. Uncertainty sources, sometimes combined with a narrative storyline. can result from lack of information or from disagreement about what is known or even knowable. It may have many types of sources, from quantifiable errors in the data to sensitivity ambiguously defined concepts or terminology, or uncertain projections of human behaviour. Uncertainty can therefore Sensitivity is the degree to which a system is affected, either be represented by quantitative measures, for example, a adversely or beneficially, by range of values calculated by various models, or by qualita- tive statements, for example, reflecting the judgment of a climate variability or climate change. The effect may be team of experts. direct (e.g., a change in crop yield in response to a change in the mean, range, or variability of temperature) or indirect B. Uncertain situations are those in which the probability of (e.g., damages caused by an increase in the frequency of potential outcomes and their results cannot be described coastal flooding due to sea level rise). by objectively known probability distributions, or the out- comes themselves, or the results of those outcomes are indeterminate (USACE, 1992) stationarity Stationarity assumes that natural systems fluctuate within united nations framework Convention on an unchanging envelope of variability. Stationarity is a Climate Change (unfCCC) foundational concept that permeates training and practice in water-resource engineering. It implies that any variable The Convention was adopted on 9 May 1992 in New York (e.g., annual streamflow or annual flood peak) has a time- and signed at the 1992 Earth Summit in Rio de Janeiro by invariant (or 1-year­periodic) probability density function more than 150 countries and the European Community. Its (pdf ), whose properties can be estimated from the instru- ultimate objective is the "stabilisation of greenhouse gas 70 Glossary of Terms concentrations in the atmosphere at a level that would change, including climate variability and extremes. Vulner- prevent dangerous anthropogenic interference with the ability is a function of the character, magnitude, and rate of climate system". It contains commitments for all Parties. climate change and variation to which a system is exposed, Under the Convention, Parties included in Annex I (all its sensitivity, and its adaptive capacity. 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