Assessment of Sediment Load and Erosion in the Sokoto River Basin, North West Nigeria

The Sokoto River, draining an extensive catchment across Kebbi, Sokoto, and Zamfara states in North West Nigeria, carries substantial suspended and bedload sediment derived from intensively cultivated catchments, presenting challenges for reservoir sedimentation management and water quality at downstream intakes. This study assesses the suspended sediment load and catchment erosion dynamics of the Sokoto River Basin through integration of field gauging, remote sensing, and empirical erosion modelling. Suspended sediment concentration and discharge were measured at four gauging stations over two hydrological seasons, enabling construction of sediment rating curves for load estimation. The Revised Universal Soil Loss Equation was applied spatially across the catchment using GIS-integrated rainfall erosivity, soil erodibility, slope length and steepness, cover management, and support practice factor layers derived from satellite data and soil survey records. Remote sensing change detection using multi-temporal Landsat imagery quantified vegetation cover decline over a twenty-year period as a driver of increasing erosion rates. Reservoir bathymetric survey data from Goronyo Dam were analysed to derive long-term average trap efficiency and annual sedimentation rates. Results indicate that annual sediment yield has increased by approximately thirty percent over the monitoring period, driven principally by agricultural encroachment on riparian buffers. Watershed management interventions are recommended for the upper catchment. Keywords: sediment load, erosion, Sokoto River, RUSLE, reservoir sedimentation.