Evaluation of the aquifer characteristic of Nanka Sands using hydrogeological method in combination with Vertical Electrical Sounding (VES)

Abstract

In this study, we have coupled surface geophysical method with pumping test results to provide a cost effective and efficient alternative in aquifer parameter estimation. Vertical Electrical Sounding (VES) was carried out at 40 sites in the study area for the identification of the vertical variation in subsurface lithology and for the characterization of the aquifer system of the study area. The interpretation of the VES data revealed 3 to 5 geoelectric units with the depth to aquifer varying from 7 to 108m and the resistivity of the saturated layer varying between 42.9 and 8829 ohm-m. Using the geoelectric data, aquifer depth, hydraulic head and aquifer resistivity maps were prepare using appropriate software. Aquifer characteristics in the form of transmissivity and hydraulic conductivity calculated from interpreted VES results varied from 0.48 to 19.50m2/day and 0.06 to 3.75m/day respectively. This coupling has proved useful and most valuable in areas of scarce data such as the study area.