Assessment of Land Use Change Impacts on Water Yield in the Upper Kaduna River Catchment, North West Nigeria

Land use change in the Upper Kaduna River catchment has been rapid over the past two decades, driven by agricultural expansion, urban growth, and deforestation, with potential consequences for river flow regimes and water availability. This study assessed the impact of land use change on water yield in the Upper Kaduna River catchment using the Soil and Water Assessment Tool hydrological model. Land use maps for 2005, 2013, and 2022 were derived from Landsat satellite imagery and used as model inputs. Model calibration and validation were performed using streamflow data from two gauging stations within the catchment. Simulated water yield under each historical land use scenario was compared to evaluate the effect of observed land cover changes on hydrological response. Results showed that forest to cropland conversion was the dominant land use transition, accounting for 34 percent of the catchment area over the study period. Simulated annual water yield increased under the 2022 land use scenario relative to 2005 baseline conditions, attributed to reduced evapotranspiration from deforested areas and higher surface runoff. However, baseflow declined, indicating reduced groundwater recharge and potential dry-season flow deficits. The study recommends reforestation of headwater areas within the Upper Kaduna catchment to restore groundwater recharge capacity and stabilise dry-season flows, integrated with catchment-wide land use planning coordinated between Kaduna State and Katsina State authorities. Keywords: land use change, water yield, Kaduna River, Soil and Water Assessment Tool, hydrological modelling.