Estimating the effect of climate change on the hydrology of Ssezibwa catchment, Uganda

This study investigates the potential effects of climate change on the hydrology of Ssezibwa catchment in Uganda. The study employs statistical downscaling techniques, which have of recent proved useful in deriving more detailed and reliable climate change scenarios for use in hydrological models for impact assessment. The first part of this study investigates the current climatic trends in the region. Future climate change scenarios are obtained from the UK Hadley climate model (HadCM3) and downscaled to the local climate of the study area. The downscaled results were used as inputs to the WetSpa hydrological model, a physically based distributed rainfall-runoff model, which was used to simulate the resulting hydrological changes. One of the key findings was that climate change is actually taking place in the study area. The results further showed that precipitation in the study area will generally decrease while temperatures will increase with 1-4°C in the dry periods. These changes will have significant impact on the river discharge by reducing the flows in the dry periods especially between May and September, while heavy floods were simulated for the wet months between November and March. In the 2020’s these changes were shown to be small, but they will increase significantly beginning the 2050’s. These results provide new findings on the effects of climate change on water resources in Africa. However, since the downscaling process is associated with much uncertainty, the findings should provide a basis for further research of especially the downscaling of precipitation data.status: publishe