Climate change projections indicate that rainfall may become more extreme in future. In addition to increased flood risk this will tend to make river flow and soil moisture more variable, which will present further challenges to ensuring water security in the future. However, there may be a silver lining in that underground water resources may be replenished. Groundwater is often neglected in climate impact analyses. Recent research by Martin Todd and colleagues from UCL, 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, published in Nature Climate Change show that groundwater resources are replenished, on average, 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. The analysis further shows that variability in rainfall is projected to increase in the future which may favour replenishment of groundwater resources. As such groundwater may play a crucial role in adapting to an increasingly extreme climate.

Find out more...

• Climate and water resources
• GroFutures: understanding sustainable groundwater resources in Africa
• Martin Todd
• Read paper in Nature Climate Change