A combined GIS, remote sensing and geophysical methods for groundwater potential assessment of Ilora, Oyo central, Nigeria

The unavailability of water has been a major threat to agricultural and commercial activities in Ilora, Oyo central, Nigeria. This study combined GIS, remote sensing, and geophysical methods for groundwater potential zone mapping within the area in an attempt to identify prospective zones for borehole drilling activities. Landsat 8 OLI, ASTER DEM, geological, geophysical, and soil data of the research area were acquired for this study. To map the groundwater potential of the area, eight thematic layers that influence groundwater occurrences and movement controlling factors such as, geology, elevation, slope, land use land cover (LULC), fault proximity, soil, lineament density, and drainage density were mapped out from the acquired data of the area. The influence of each theme and subunit/class on groundwater recharge based on previous studies were evaluated using Analytical Hierarchical Process (AHP). The groundwater potential of the area of study was qualitatively classified into five classes, namely: very high, high, moderate, low, and very low which account for 0.3%, 7.8%, 54.8%, 35.6%, and 1.5% of the total area, respectively. The results were cross validated using well data from the area and 88.9% correlation and 0.74 kappa coefficient were achieved. The groundwater potential map generated in this research could be used as a preliminary reference in selecting suitable sites for groundwater resource exploitation in the area to ameliorate the current scarcity of water in this region.