Hydrogeological Implication of Electrical Resistivity Sounding in Ita-Eku, Ado Ekiti, Nigeria

Abstract

Electrical resistivity prospecting method was used in evaluating the groundwater potential of Ita-Eku, southeastern part of Ado-Ekiti, Ekiti state, Nigeria using the vertical electrical sounding technique. A total of seven electrical soundings were conducted using the Schlumberger electrode array. The data acquired were interpreted qualitatively and quantitatively and were presented as tables, charts and section. The interpreted models revealed three to four geo-electric layers namely; topsoil, clay/lateritic soil, weathered/fractured layer and fresh basement. The topsoil which is relatively thin has thickness ranging between 0.8 and 2.5m while the resistivity values range from 26 to 171 Ω-m. The second layer has thickness ranging from 2.5 – 5.9 m and resistivity values from 5 to 19 Ω-m. The third layer is the weathered/fractured layer with thickness ranging from 5.9–35.3 m and the resistivity values range from 171 to 404 Ω-m. The basement resistivity values range between 711 and 3466 Ω-m. First and second order (Dar Zarrouk parameters) data were used to generate the geo-electric section, overburden thickness chart and longitudinal conductance chart. These section and charts were considered in generating the groundwater potential table. The groundwater potential table shows that about 28% of the entire study area falls within zone rated as having high groundwater potential, while about 28% of the study area constitutes the low groundwater potential rating and the remaining 44% has moderate groundwater potential rating.