Application of Electrical Resistivity in Delineating Potable Groundwater Layers in a Typical Coastal Community: A Case of Federated Okerenkoko, Nigeria

Abstract

Assessing potable groundwater in coastal terrain is often a daunting task due to the peculiarities of the environment. In this paper, two vertical electrical sounding (VES) were obtained using Petro-Zenith resistivity meter (PZRM) with Schlumbeger configuration to delineate a potential/viable aquifer layer for potable groundwater exploitation in Federated Okerenkoko Island, Gbaramatu Kingdom, Nigeria. A maximum current electrode spacing of 600-1200 m was probed. The result obtained showed two aquiferous horizons (confined/unconfined) below and above a thick clay layer encountered at a depth of 327.36 m corresponding to apparent resistivity of 1097.07 Ωm and a corrected resistivity of 676.96 Ωm respectively. The inferred lithological layers/units of rocks obtained in the study include an overburden of fine grain sand, dark grey laterite, clayey sand, sandy clay, clayey silt and find to medium coarse sand. Hydrogeological/geophysical curve types obtained in the study revealed the KHQ and AA type which is an indication of a deep and shallow aquifer respectively. It is recommended that to access potable groundwater devoid of external influence in the study area, a minimum depth of 762 m should be drilled.