Groundwater resilience to climate change in Africa

Groundwater provides most of the domestic water supply in rural Africa and supports poverty reduction through irrigation. Climate change along with rapid population growth are likely to impact all water resources, but the response of groundwater will be slower than that of surface water. This could provide a potential buffer to support adaptation strategies. A key advantage of groundwater is its reliability: aquifer storage ensures that groundwater supplies can be maintained during periods of little or no rainfall and help to even out meteorological variability. As a natural store of water, aquifer storage is many orders of magnitude greater than that which can be achieved through constructing surface water reservoirs. The IPCC Fourth Assessment report review of climate model projections shows a consistent pattern of progressive warming of the climate in all regions of Africa, but a much less consistent pattern for rainfall (Solomon et al. 2007). The increased temperature will lead to higher rates of evapotranspiration and likely increase in the intensity and variability of rainfall (Conway 2011). Although the exact impact on runoff and groundwater recharge is unclear, most scientists agree that both will become less reliable. Making more use of groundwater will therefore be critical in helping communities and countries adapt and build resilience to changes in climate. This is likely to include the increasing use of groundwater for both small-scale household/village irrigation and largerscale commercial irrigation; and increased use of motorized borehole pumps for reliable urban water supply (small towns to larger conurbations). The benefits of groundwater are well recognised (MacDonald et al. 2005), but there is limited knowledge of African groundwater resources and how they might respond to changes in climate. There has been little systematic assessment of groundwater storage and availability which was reflected in the paucity of information on groundwater presented in the IPCC Fourth Assessment Report and Technical Paper on Water, where there was major uncertainty as to how changes in climate may affect groundwater (Solomon et al. 2007; Bates et al. 2008).