Piezometric surface deduced from vertical electrical sounding data

Abstract

In hydrogeological studies the knowledge of the water table is very essential. In this work, one hundred and eight vertical electrical soundings were carried out, with the view of unravelling the hydrogeological characteristics of Kuri River Basin, Kaduna, Nigeria. The water table for eleven hand dug wells were directly measured and a comparison was made with cumulative resistivity (Σρa) plots at such well sites. The apparent resistivities were obtained using the Schlumberger electrode array configuration with a spread current electrode of 300m. The data obtained was processed using the GP Resound program. It was found that all the depths to the water table for the measured wells fell within the 3^rd segment of the cumulative plots with a standard deviation of 0.04. The 3^rd segment or 3^rd break of the plot is considered as the zone of permanent saturation. It was on the basis of these cumulative plots that the depths to water table of all other sites sounded were deduced. By this, it is now possible to infer depths to water table from vertical electrical soundings without necessarily undergoing direct well measurements.

Keywords: Water Table/Piezometric Surface, Vertical Electrical Sounding, Hydrogeology, Cumulative Resistivity Plot