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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.
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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 • - Temperature • Precipitation • Evapotranspiration • Sea level rise • Soil moisture • - Recharge • Discharge • Storage • Quality
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 • Management of grw. storage • Protection of grw. quality • Managing demands for grw. • Managing grw. discharge • Building the adaptive capacity for grw. management
Management Aquifer Recharge: MAR Managing the Water Buffer: 3R No regret measures EXAMPLE : MGT OF RECHARGE AND STORAGE
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
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
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