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GROUNDWATER AND CLIMATE CHANGE MANAGING THE WATER BUFFER Albert Tuinhof Groundwater Development and Management GW-MATE Specialist AGW-NET Training of Trainers on Groundwater Management Dar es Salaam - November 16-20, 2009 MAIN BACKGROUND MATERIAL • Adaptation Options for Climate Change Impacts on Groundwater Resources (World Bank, SKM – 2009) • Groundwater and Climate in Africa (Hydrological Sciences Journal, volume 54, number 4, August 2009) – Richard Taylor, Antonis D. Kousis and Callist Tindimugaya • CPWC: Cooperative Panel/Program on Water and Climate (since 2003) • Managing the Water Buffer (Acacia Water, Meta Meta, BGR – 2009) CLIMATE CHANGE IMPACTS ON GROUNDWATER - Recharge Discharge Storage Quality - Temperature Precipitation Evapotranspiration Sea level rise Soil moisture RECHARGE : CLIMATE CHANGE MESSAGE Doll and Florke (2005): global scale 2% increase against 4% increase in rainfall 70 % decrease in the western part of Southern Africa and >30 % increase in the Sahel Estimates not appropriate to scale down to country or basin/watershed level (IN)DIRECT CLIMATE AND NON-CLIMATE FACTORS RECHARGE •Precipitation: main driver: not only the magnitude but also intensity, frequency, seasonality •Temperature and CO2 may affect evapotranspiration > portion of rainfall that infiltrates •Changes in river flow will affect infiltration (and discharge) • Land cover and land use <> climate change • Non climate factors: land use changes, population growth, poor management CLIMATE CHANGE IMPACTS: Global estimates give regional trends , not appropriate to scale down to country /basin level. Climate factors (direct/indirect) and non-climate factors Changes in natural climate variability IMPLICATIONS FOR GRW DEPENDENT SYSTEMS Impacts of droughts and floods on • Rural and urban water supply • Agriculture • Ecosystems What are climate change impact <> groundwater related issues in yr country?? CLIMATE CHANGE ADAPTATION Adaptation: management responses for grw. dependent systems to risks associated with climate variability and climate change • Managing grw. recharge Managing groundwater recharge • Management of grw. storage • Protection of grw. quality • Managing demands for grw. • Managing grw. discharge Protecting groundwater quality Managing demand for groundwater Managing groundwater storage Managing groundwater discharge • Building the adaptive capacity for grw. management EXAMPLE : MGT OF RECHARGE AND STORAGE • • Management Aquifer Recharge: MAR Managing the Water Buffer: 3R No regret measures MAR building infrastructure and/or modifying the landscape to intentionally enhance groundwater recharge Recharge enhancement provides additional storage Therefore…..Storage!! There is a need for small scale, low tech, low cost, sustainable solutions! Some figures • Surface water storage per capita – Ethiopia 43m3 – South Africa 750m3 – North America 6150m3 • Village ponds or domestic rainwater storage could add 5m3 per person • Each additional 10mm groundwater recharge could add 200m3 per person 12 Storage = buffering 3R concept – Recharge, Retention and Reuse • Local (cisterns) and subsurface storage (active use of aquifer) of surface water for both water- and food security • Its not about allocation scarce water but to catch and retain water and extend the chain of use and reuse as possible within a basin • Introduce buffer management at scale – basin by basin. Not piecemeal/scattered • Subsurface storage largest potential in terms of m3 13 EXAMPLE : MGT OF RECHARGE AND STORAGE 14 15 EXAMPLE : MGT OF RECHARGE AND STORAGE EXAMPLES KITUI SAND DAM Abstraction well Subsurface storage HOW IT WORKS • Dam drops the flow velocity and results in sedimentation and percolation of water • Increasing the water availability by storing water in the riverbed and banks • Increased availability of water for domestic and other uses such as livestock, irrigation and regeneration of natural vegetation IMPACTS OF SAND DAMS IN KITUI Vulnerability Categories Agriculture Special aspects Vulnerability indicators Before dam construction After dam construction # of cash crops 1.5 2.8 % irrigated crops 37 68 Water collection Domestic (minutes) 140 90 Water collection Life Stock (minutes) 110 50 3 1 Gender Average walking distance women to water (km) Economic Income (US$./year) 230 350 Health % households suffering from malnutrition 31.6 0 Every Body has the right to be buffered