Groundwater Exploration using 1D and 2D Electrical Resistivity Methods

Abstract

Integrated geophysical techniques involving 2D electrical resistivity imaging (ERI) and vertical electrical sounding (VES) were used to delineate groundwater potential zones for borehole siting in the Pru District of the Brong Ahafo Region of Ghana. The ABEM Terrameter LS was employed in the survey. A total of fifteen (15) 400 m - ERT profiles and thirty-one (31) VES points were investigated using the Schlumberger protocol. The Res1DINV and Res2DINV inversion software were used for data analysis. The 2D ERI images showed a lot of fractures within the subsurface of the study area. The results of the VES generally revealed either three or four subsurface geological layers at the selected points. The second and third layers were found to possess relatively low-to-moderate resistivity values indicative of potential aquifer zones. The resistivity of the fourth layer indicated the presence of slightly-fractured to fresh bedrock. The borehole logs depict four sequences: brownish or lateritic sandy clay overlying highly weathered sandstone which is underlain by moderately weathered sandstone and highly fractured sandstone basement.

Keywords: Electrical resistivity tomography, vertical electrical sounding, groundwater, aquifer, geological layer and hydrogeology.