Geospatial Modelling of Groundwater Recharge Zones in the Sokoto-Rima Basin

Sustainable groundwater management in the semi-arid Sokoto-Rima Basin of North West Nigeria requires spatially explicit delineation of recharge zones to guide well siting, abstraction regulation, and land use planning decisions. This study develops a geospatial model of groundwater recharge potential for the Sokoto-Rima Basin using a multi-criteria GIS framework integrating hydrogeological, topographic, pedological, and land cover parameters. Data layers including aquifer type, lineament density, drainage density, slope, soil infiltration capacity, rainfall erosivity, and land cover imperviousness are compiled from geological maps, satellite imagery, SRTM DEM analysis, and FAO soil datasets. Analytic Network Process weighting accounts for interdependencies between criteria, addressing a methodological limitation of the simpler AHP approach applied in earlier studies of northern Nigerian basins. The resulting groundwater recharge potential map is classified into five zones and validated against specific yield data from 186 boreholes in the Rima-Upper Sokoto and Gwandu Formation aquifer systems. Validation yields a prediction success rate of 82 percent at high-potential locations. Model sensitivity analysis identifies soil infiltration capacity and lineament density as the parameters with greatest influence on the classification outcome. The study provides the Sokoto-Rima Basin Development Authority and the Sokoto and Zamfara State Water Boards with a spatial planning tool for strategic groundwater resource development. Keywords: groundwater recharge, geospatial modelling, Sokoto-Rima Basin, analytic network process, GIS.