Estimating the effects of climate change on groundwater recharge and baseflow in the upper Ssezibwa catchment, Uganda

Abstract The effects of climate change on groundwater recharge and baseflow in the upper Ssezibwa catchment, Uganda, are investigated. The study first examines historical data, which indeed reveal evidence of climate change based on trends observed in temperature and discharge. For the climate change study, the statistical downscaling model (SDSM) is used to downscale future climate change scenarios, which were obtained from the UK HadCM3 climate model. The downscaled climate is used as input to the WetSpa hydrological model, a physically-distributed rainfall—runoff model, which was used to simulate the resulting hydrological changes. Downscaled climate shows an increase in precipitation in the wet seasons (March—May; October—December) ranging from 30% in the 2020s to over 100% in the 2080s. The corresponding rise in temperature ranges between 1 and 4°C. These changes are shown to give rise to intensification of the hydrological cycle. The mean annual daily baseflow for the current period of 157 mm/year (69% of discharge), is expected to increase by 20–80% between the 2020s and 2080s. The corresponding increase in recharge ranges from 20 to 100% from the current 245mm/year. The findings provide a basis for further research in the downscaling of climate data and sensitivity analysis for simulated hydrological changes in the catchment.

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