| dc.description.abstract | This study addresses the relative influence of future climate and land use changes on River Rwizi’s hydrology, a currently water-stressed catchment in western Uganda. Although many studies have evaluated these factors separately, few have considered their combined effects or quantitatively distinguished their relative contributions. Using an ensemble of six CORDEX Regional Climate Models (RCMs), the study projected future temperature and precipitation changes under moderate (RCP 4.5) and high (RCP 8.5) emissions scenarios. The Cellular Automata-Artificial Neural Network (CA-ANN) model was applied to predict land use changes by 2048. Hydrological simulations were then performed using the Soil and Water Assessment Tool (SWAT) under three scenarios: land use change alone, climate change alone, and a combined scenario. Results showed that land use change alone would increase River Rwizi’s total annual flow by 47.3%, while climate change alone would decrease it by 9.8%. The combined scenario showed a 20.9% increase in annual flow, highlighting the stronger influence of land use changes on total annual runoff. All scenarios projected increases in high-flow events, based on 10-year flow quantiles, with the combined scenario producing the highest increases: 77.7% under RCP 4.5 and 75.05% under RCP 8.5. Climate change alone also significantly increased high flows, with rises of 64.7% (RCP 4.5) and 73.5% (RCP 8.5). In contrast, low flow quantiles decreased under both land use and climate change scenarios, particularly under the combined scenario, suggesting potential low-flow challenges for water supply. Attribution analysis identified climate change as the primary driver of increased high flows, heightening flood risks, while land use changes were more influential on total annual and extreme low flows, impacting water availability for Mbarara. The findings underscore the importance of integrated water management that addresses both factors. To ensure sustainable water resources, a dual approach is recommended. First, implement stringent land use policies to help regulate annual and low flows critical for consistent water supply. Second, adopt climate adaptation strategies, such as flood management, to mitigate the risks posed by increased peak flows. This balanced approach is essential for sustaining water supply in Mbarara and maintaining the River Rwizi’s hydrological balance. | en_US |
