Aspects of Geophysical Exploration for Groundwater Using Vertical Electrical Sounding (VES) in Parts of University of Benin, Benin City, Edo State

Abstract

A geophysical survey using vertical electrical sounding (VES) was  undertaken within the University of Benin (Ugbowo Campus) in an attempt to ascertain aspects of the hydrogeological parameters for groundwater exploitation. Six (6) vertical electrical soundings with electrode spacing of 215m AB/2 were occupied along the traverse, with the aid of ABEM SAS 1000 Terrameter set. The data were interpreted using the IXID and 3-D fieldmap computer softwares. The subsurface stratigraphy is as follows; (262.43-784.7m); topsoil, (205.65-3666.4m); wet laterite, (44.017-2201m); anomalous soil, (601.03-1450m); clayed/silty sand, (2712.38-11741m); dry sand, and (2909.7-12423m); as aquifer. The results reveal depth to water table ranges of 31.2-65.5m. The range of values of minimum thickness of the aquifer across the VES is from 45-63m. VES 3 is the shallowest and may be the cheapest to drill and install a borehole. VES 6 with a inferred depth of 63-65.5m, will probably be the best area to site a borehole in spite of the expected cost imperatives. The area shows slight spatial variations and plausibly attests to natural inhomogeneity,  anthropogenic interplay in the course of the development of the area via
construction, and very marginal susceptibility to contamination from the health centre and hostels within the study area. Furthermore, the results conformed to those of previous writers who described the aquifer as sandy and highly prolific