Future Changes in Climate and Hydroclimate Extremes in East Africa

Climate change is affecting the agriculture, water, and energy sectors in East Africa and the impact is projected to increase in the future. To allow adaptation and mitigation of the impacts, we assessed the changes in climate and their impacts on hydrology and hydrological extremes in East Africa. We used outputs from seven CMIP-6 Global Climate Models (GCMs) and 1981-2010 is used as a reference period. The output from GCMs are statistically downscaled using the Bias Correction-Constructed Analogs with Quantile mapping reordering method to drive a high-resolution hydrological model. The Variable Infiltration Capacity and vector-based routing models are used to simulate runoff and streamflow across 68,300 river reaches in East Africa. The results show an increase in annual precipitation (up to 35%) in Ethiopia, Uganda, and Kenya and a decrease (up to 4.5%) in Southern Tanzania in the 2050s (2041-2070) and 2080s (2071-2100). During the long rainy season (March-May), precipitation is projected to be higher (up to 43%) than the reference period in Southern Ethiopia, Kenya, and Uganda but lower (up to -20%) in Tanzania. Large parts of Kenya, Uganda, Tanzania, and Southern Ethiopia show an increase in precipitation (up to 38%) during the short rainy season (October-December). Temperature and evapotranspiration will continue to increase in the future. Further, annual and seasonal streamflow and hydrological extremes (droughts and floods) are projected to increase in large parts of the region throughout the 21st century calling for site-specific adaptation.

Automated summary

Climate change is causing impacts on agriculture, water, and energy sectors in East Africa, which are projected to intensify in the future. To assess these impacts and facilitate adaptation and mitigation measures, the study evaluated climate changes and their effects on hydrology and hydrological extremes in the region. Utilizing data from seven global climate models, the study downscaled the outputs to a high-resolution hydrological model. Results indicate that there will be an increase in annual precipitation in Ethiopia, Uganda, and Kenya, but a decrease in Southern Tanzania in the 2050s and 2080s. The study also projects increased precipitation during the long and short rainy seasons, as well as rising temperatures and evapotranspiration, highlighting the need for site-specific adaptation strategies throughout the 21st century.