New approach of gradient profiling for tracking of low resistivity shallow fracture in hard rock area for groundwater exploration

The resistivity survey for the study of subsurface hydrogeology is a continuously evolving science, which either adopts different techniques or combination of techniques to standardize the approach. The gradient profiling is done in the presence of horizontal electric field which is one of the techniques to locate the low resistivity response within the hard rock formations. This low is obtained due to presence of inhomogeneity in the host rocks. The attempt has been made to develop the concept of parallel gradient sub-profile, formulation and computation of geometrical factor, and demonstration through an actual field example in the hard rock area. The present study clearly shows that the region of low resistivity zone can easily be delineated to select a point for conducting geoelectrical sounding for knowing the information about its depth, thickness, and resistivity which are necessary requirements for ground water exploration. It can be inferred from the above study that parallel gradient sub-profile with respect to main gradient profile is useful tool for delineating low resistivity zone due to presence of fractured sandstone rocks saturated with groundwater which can be exploited.