Integrated Landsat Imagery and Geophysical Exploration for Groundwater Potential Evaluation of Okene and Its Environs, Southwestern Nigeria

Abstract

In this study, an integrated remote sensing and geophysical (aeromagnetic and geo-electric) methods was employed to assess the potential of groundwater in a basement complex terrain of Okene and its environs, Southwestern, Nigeria. Landsat imagery acquired over the study area was processed in the Geographic Information Systems (GIS) environment to delineate the surface lineaments, drainage networks and their orientations. Aeromagnetic data over the area were analyzed and its derivative maps were interpreted to further map the structures and the geology in the subsurface; depths to magnetic sources were determined using spectral analysis. Vertical Electrical Sounding (VES) of geo-electric method was interpreted to map the subsurface geology layers. The results of the integrated data were correlated with borehole yield data of the area for effective interpretation. Delineated lineaments from the azimuth, frequency plot showed dominant trends in the NE-SW and NNE-SSW directions. Radial average power spectrum revealed the depth to magnetic sources between 100 and 2500 m and the interpreted VES data characterized the area into three to four subsurface layers. In correlating the results with borehole yield data, the zones with high lineament density and low/negative magnetic anomaly were categorized as high groundwater potential zones while areas with low lineament density and high/positive magnetic anomaly as low groundwater potential zones. This study will guide efficiently subsequent groundwater drilling program in the study area.