Satellite-Enhanced Groundwater Prospect Assessment in a Crystalline Basement Terrain Using Landsat Imageries and DEM Data Around Ilorin Metropolis and Adjacent Areas, Southwest Nigeria

Abstract

An assessment of the Crystalline Basement Complex (CBC) terrain of the province around Ilorin, Southwestern Nigeria, was carried out to evaluate its groundwater potential. The study aimed at investigating the hydrogeomorphological and geological/hydrogeological characteristics of the study area. This was with a view to classifying the study area into different groundwater potential zones, in order to delineate and recommend prospective areas for subsequent detailed geophysical study and drilling campaign. Drainage map, topographic map, and geological maps of the study area were acquired and integrated with Satellite imageries comprising Landsat Enhanced Thematic Mapper Plus (ETM+) 2000 and ASTER GDEM covering the area, and processed using the ArcGIS 10.4 software. The hydro-geomorphological map and hydrogeologic lineament density maps were generated from the processed remotely sensed data. Results from the processed Digital Elevation Model (DEM) showed five distinct hydrogeomophic units which include: Dambos (valleys) (156–270 m a.s.l), the Pediplain (270–305 m a.s.l), lower Pediment (305–330 m a.s.l), upper Pediment (330–355 m a.s.l) and the residual hills (355–390 m a.s.l). The hydrogeologic lineament trends show N-S, NNE-SSW, NE-SW and NW-SE trends. The hydro-significant lineament density map reveal five (5) lineament cluster zones in the range of 0.00–1.25, 1.25–2.50, 2.50–3.75, 3.75–5.00 and 5.00–5.60 km per km². Cross examination of the hydro-geomorphological map and lineament density map, in a Geographical Information System (GIS) environment, enabled the characterization of the study area into five different classes of very low, low, moderate, high and very high groundwater potential zones. It is concluded that groundwater potential of the area around Ilorin was generally of very low to low rating. However, there are few areas with moderate groundwater potential.