Geoelectrical Exploration For Groundwater In A Crystalline Basement Terrain: The Case Of Obudu, S.E. Nigeria

Abstract

Vertical electric sounding (VES) method using schlumberger electrode configuration was used to conduct a survey for groundwater in Obudu area, S.E. Nigeria, in an attempt to define the geoelectric structure, variation in thickness and potential groundwater zones in the subsurface of the area. The survey area is located between 6^o 30^/ N and 6^o 45^/ N latitude and between 9^o 00^/ E and 9^o 30^/ E longitude.

Nineteen vertical electric sounding (VES) points were surveyed using ABEM Terrameter SAS 300B with a maximum current electrode separation of 350 meters. Results of the survey and the computer modeling identified a three to four layer geoelectric model. The geoelectric structure has been differentiated into possible lithological units of sandy clay, clay and sand. The fourth layer shows a high resistive unit which is indicative of fresh rock. The resistivity values and thicknesses of the third layer indicate water saturation and potential aquifer in the area.

KEY WORDS: Vertical Electrical Sounding, Electrode Configuration, Geoelectric model.

Global Journal of Geological Sciences Vol.3(1) 2005: 49-53