On the Application of Coefficient of Anisotropy as an Index of Groundwater Potential in a Typical Basement Complex of Ado Ekiti, Southwest, Nigeria

Abstract

This paper examines the application of the Dar Zarrouk parameter, the Coefficient of Anisotropy to Groundwater Potential Evaluation in a typical Basement Complex Terrain of Ado-Ekiti Southwest, Nigeria. A regional Geoelectric Depth sounding was carried out across the metropolis using the Schlumberger electrode array. Resistivity-depth image in terms of layer thickness and resistivity was used to compute the Coefficients of Anisotropy for the VES locations occupied. Thematic maps of the geoelectric parameters were generated using the Concept of Geographical Information System (GIS). Comparative Map Analysis revealed that a range of 1.3 to 1.6 Anisotropy values was observed across the zones characterized by thick overburden, Weathered Basement Thickness in excess of 25m, low weathered basement resistivity, fractured bedrock and basement depressions in the study area. Anisotropy values ranging from 1.8 to 2.8 were observed across the basement ridges and zones characterized by thin overburden, Weathered Basement Thickness of generally less than 15m and Weathered Basement resistivity greater than 1500 Ω-m with least groundwater potential. The regions of Anisotropy values ranging from 1.3 to 1.6 are demarcated as high groundwater potential zones. Areas characterized by higher Anisotropy values can be associated with low porosity and permeability with less hydro geological appeal.