SWAT simulation of streamflow in Sironko catchment on Mt. Elgon, Eastern Uganda

We determined the 2025-2040 impact of climate and land use land cover change on streamflow in the Sironko catchment. LULCC was predicted using Cellular Automata Markov. The climate was statistically downscaled from the 29 GCMs of the IPCC Fifth Coupled Model Intercomparison Project using the delta method of the Agricultural Model Inter-comparison and Improvement Project under five climate regimes and Representative Concentration Pathways 4.5 and 8.5. Streamflow was simulated using the Soil and Water Assessment Tool. One sample t-test confirmed significant differences in the 1980–2010 and 2025–2040 streamflow. A second-degree regression model computed the contributions of climate and LULCC on streamflow. Significant differences (p < 0.05) were detected in the 1980–2010 and 2025–2040 streamflow. Climate change will increase streamflow by 7.6–49.20% and 6.50–59.20% under RCP 4.5 and RCP 8.5 while LULCC will increase streamflow by 4.10–39.20% and 1.30–45.30% under RCP 4.5 and RCP 8.5 calling for a multifaceted approach to mitigate the identified impacts.