Hydrogeophysical Implication of Geoelectric Sounding at Igarra Comprehensive High School, Akoko Edo Local Government, Nigeria

Abstract

Electrical resistivity method was used to carry out hydrogeophysical study in order to evaluate the groundwater potential of Igarra Comprehensive High School, Akoko Edo Local Government, Nigeria. The vertical electrical sounding technique (VES) was adopted for the resistivity method. A total of eighteen electrical soundings were conducted across the area using the Schlumberger electrode array with AB/2 varying from 1 to 65 m. After the data acquisition, interpretation was carried out qualitatively and quantitatively and the results were presented as sounding curves, tables, charts, maps and geoelectric sections. The generated geoelectric layers from the sounding curves revealed four geologic layers: the topsoil, the weathered layer, the partially weathered/fractured basement and the fresh basement with their resistivity values ranging from 129.1 to 956.4 -m, 6.8 to 1491.1 -m, 261.3 to 776.6 -m and 1515.6 to 2653.5 -m respectively. The overburden thickness in the study area varies from 5.5 to 23.5 m. The groundwater potential map enabled in the classification of the study area into: low, medium and high groundwater potential area. About 85% of the study area falls within the low groundwater potential rating while about 10% constitutes the medium groundwater potential rating and the remaining 5% constitutes high groundwater potential rating. Keywords: Groundwater, overburden, electrical resistivity, basement, geoelectric sounding.