Modelling the Impacts of Land Use Land Cover Change on Hydrology and Sediment Yield in a Water Catchment in Central Uganda

This study investigated the influence of land use land cover change (LULC) on hydrology and sediment yield in a water catchment in Uganda. The Soil and Water assessment Tool (SWAT) model was used to assess the impacts of LULC on hydrology and sediment yield in upper Ssezibwa catchment. The calibrated and validated SWAT model based on observed streamflow data demonstrated good performance as indicated by the values during calibration (R<sup>2</sup>=0.85, NSE=0.82, KGE=0.76, PBIAS = -18.5) and validation (R<sup>2</sup>=0.72, NSE=0.66, KGE=0.66, PBIAS= -19.3). The model performance of for sediment yield is also good during calibration (R<sup>2</sup>=0.80, NSE=0.81, PBIAS = -17) and validation (R<sup>2</sup>=0.74, NSE=0.76, PBIAS= -19.7). Overall accuracy assessment of over 80% and Kappa statistics of 0.82, 0.84 and 0.80 for the years 2002, 2012 and 2022 respectively was satisfactory. Results indicated changes in the various LULC types in the catchment which increased the contribution to streamflow by surface runoff (130.2%) and 111.45% in 2002 - 2012, and 2012 – 2022 respectively, while Lateral flow and ground water flow decreased by -2.26% and -3.23% as well as -5.78% and -9.2% in 2002 - 2012, and 2012 – 2022 respectively. Sediment yield increased by 21.25% in 2002-2012 and 28.33% in 2012-2022. Results provide a solid foundation for better land use and water resource planning, monitoring and management as well as minimizing the costs of the impacts of flooding in Upper Ssezibwa catchment.