Variations in groundwater recharge and associated risks to groundwater supplies over Uganda

Abstract

Majority of Uganda’s population relies on groundwater as an accessible source to meet their water demands especially in times of prolonged dry seasons. Its importance will likely increase with a changing climate where extreme events like drought are projected to increase in the future. However, it is still unclear, how climate change will impact groundwater systems and thus the availability of this vital resource. The main objective of this study was to examine changes in groundwater recharge and its implications on groundwater availability over Uganda. This was done using a multi-model ensemble of eight global hydrological models (GHMs) of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2b) that are forced by the bias-adjusted output of four global circulation models (GCMs). The study assessed the space-time variability in groundwater recharge, the recharge/precipitation ratio, and assessed areas potentially at risk to future groundwater shortages over Uganda. The results showed that; groundwater recharge is projected to increase by 5-75% in most parts of the country with isolated decreases of 5-25% in the districts of Koboko, Yumbe, Arua, Nebbi, Moyo, & Adjumani in the Northwest, and Isingiro, Rakai, Mbarara, Kiruhura, Lwengo, Bushenyi in Southwestern Uganda, and that the contribution of precipitation to recharge is likely to decrease in the future. The study concludes that, despite of the projected increases in groundwater recharge, over 90 million people are likely to suffer from groundwater shortages in the future. The study therefore recommends that alternative sources of water should be thought of in areas bound to suffer from groundwater shortages.