Previous researches shows that resistivity values are not sufficient in adequately and correctly delineating aquiferous zone or areas of high groundwater yield in crystalline basement terrain, a complementary has been recommended, the aim of this study is to delineate fractured zones and area of groundwater potential from reflection coefficient and overburden thickness above the bedrock. Geoelectric measurements using the vertical electrical sounding (VES) method were carried out in Alakia, Ibadan Oyo State, Nigeria. Eight profiles were carried out using the Schlumberger array configuration. The data was interpreted using the method of curve matching and computer iteration (WinResist Software). Results showed that four to six geologic layers were identified in the study area and they include the topsoil, clayey, clayed sand, sandy soil, lateritic soil, weathered/highly fractured basement. The values of the reflection coefficient ranges from 0.16 to 0.78, the low values imply the study area is well fractured while the overburden thickness varies between 8.1 and 59.4m. 88% of the study area has overburden thickness that is greater than 30m, while all the VES points have reflection coefficient that is less than 0.8. The result revealed that the area is well fractured and the groundwater prospect within the area is very high.
Keywords: Alakia, aquifer potential, electrical resistivity, fractured rock, overburden thickness, reflection coefficient
