Multi-Array Hydro-Geoelectric Characterization of a Crystalline Basement Complex Environment

Abstract

The efficiency of integrated geoelectric arrays study was undertaken on a ubiquitous shallow Precambrian Crystalline Basement Complex rocks terrain of School of Earth and Mineral Sciences (SEMS) of The Federal University of Technology, Akure, southwestern Nigeria. Geophysical data acquisition was undertaken on fifteen (15) traverses in the area using Gradient, Dipole–Dipole and Schlumberger Vertical Electrical Sounding (VES) techniques. The field data were interpreted using both manual and computer iterations. The results are presented as map, sounding curves and sections. The results of the Gradient array, Dipole-Dipole and Schlumberger VES enabled qualitative, semi-quantitative and quantitative hydrogeophysical evaluations respectively. Both Gradient and Dipole-Dipole arrays indicate existence of fairly favourable hydro-geoelectric setting on the north central precinct of the area. The combined results of both arrays informed the location of 13 Schlumberger-VES points in the favourable hydro-geophysical environment. The Schlumberger VES results show that clayey overburden materials (31 – 58 Ω-m) with thickness varying between 8.7 and 16.9 m that can plausibly support abstraction of some quantity of groundwater underlie the fairly favourable northern flank. However, a fractured basement column delineated beneath VES 7 may sustain fairly adequate groundwater yield. Despite the high cost of implementing multiple geoelectrical arrays in groundwater projects, the outcome may justify the expenditure especially in cases where point of water abstraction is successfully identified principally where properties have been developed in a ubiquitous shallow bedrock environment similar to the terrain of study.