Kadayampatty Panchayat Union situated in the northern part of Salem district and adjoining the Dharmapuri district of Tamilnadu. It lies between the latitudes 11o 45ı–12o and longitudes 78o–78o 15ı in the Toposheet No 58 I/1. The study area mainly consists of late Precambrian age characterized by migmatitic gneisses, Ultramafic and Pyroxenite. In this study an attempt has been made for demarcating groundwater potential zone by using geophysical techniques. Resistivity of rock formation varies over a wide range, depending on the material, density, porosity, pore size and shape, water content, quality and temperature. In relatively porous, highly jointed and fractured formation the resistivity is controlled more by water content and quality with in the formation then by the rock resistivity. For demarcating groundwater potential zones in the Kadayampatty Panchayat Union water table analysis and ten Vertical Electrical Sounding (VES) followed by Schlumberger electrode configuration were carried out. The maximum depth of investigation was 150mts. The electrodes spread were generally in steps of five meters interval up to 50mts and 10mts interval up to 150mts. VES locations were selected within the study area with respect to their topographic features. Has been used to evaluate the geoelectrical parameters in order to demarcate the potential groundwater zones for new dugwell and borewell locations. The Lithological interpretation reveals that the presence of a maximum of five geoelectrical formations in the study area viz. Topsoil, weathered zone, fissure and fractured zone, fracture basement, and fresh basement. However all five formation do not occur throughout the study area as the maximum and minimum of geoelectric layers are four and three respectively. Similarly a thin geoelectric layer was observed in some places also. The comparatively high resistivity value with corresponding high values of thickness is indicative of a wide stretch of unweathered and unfractured fresh rock layers. A highly weathered (saturated) basement is indicated by the extremely low resistivity value. The depth to the fresh basement varies.
