Abstract

Electrical Resistivity method involving Vertical Electrical Sounding (VES) have been used to evaluate the groundwater potential and aquifer protective capacity of the overburden units within Zion Estate area. Sixty-eight Vertical Electrical Soundings were carried out using Schlumberger configuration with AB/2 varying from 1 to 65 m. The generated geoelectric section from the interpretation of the sounding curves revealed four layers - the top soil, the weathered layer, the partially weathered/fractured basement and the fresh basement. The weathered layers constitute the major aquifer unit in the area but are generally thin. The groundwater potential map revealed that 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. Hence the groundwater potential of the area is generally rated to be low. The overburden protective capacity map of the study area shows that about 75% of the area falls within the poor overburden protective capacity, while the remaining 25% constitutes the moderate/weak protective capacity rating. This suggests that the area is characterized by low longitudinal conductance which informed weak protective capacity rating of the area. Therefore the study area can be vulnerable to pollution from contaminant sources such as industrial waste, septic tanks, underground petroleum storage tanks and landfills when located close to the study area.

Key words: Groundwater, geoelectric, sounding, Schlumberger.