Heavy rains replenish groundwater supplies in Africa

Intensive rainfall in East Africa can result in widespread flooding but may have a silver lining in the form of replenishing vital groundwater supplies. New research by Richard Taylor (UCL Geography) and colleagues from Sussex University, the Tanzanian government and British Geological Survey in semi-arid Tanzania has found that very heavy rainfall that accompanies the El Niño phenomenon is vital for recharging underground aquifers in the region. In central Tanzania, there is near total dependence upon groundwater resources for public water supplies. The team's findings just twice each decade. Although pumping of groundwater from wells depletes the aquifer outside of these events, replenishment from periods of extreme rainfall is so far sufficient to sustain intensive groundwater use. This research, supported by the Department for International Development (DFID), builds on work by members of this team published earlier this year that revealed that freshwater stored in subsurface aquifers greatly exceeds that which is found at the surface in lakes and rivers. However, a key uncertainty was replenishment rates.