Geoelectrical Survey for the Exploration of Ground Water using Vertical Electrical Sounding: A Case Study of Androt District Rawlakot, Azad Jammu & Kashmir

Abstract

Vertical Electrical Sounding (VES) method has been widely used to depict the subsurface lithology, thickness and structure based on resistivity of layered media with the ultimate objective of evaluating groundwater potential. In this investigation, VES was used to outline subsurface geology to produce a 2D subsurface resistivity model based on the resistivity contrast of layered rocks, for evaluating the accessibility of groundwater in the Siwaliks group of Androt District Rawlakot, Azad Jammu and Kashmir (AJ&K). The Schlumberger electrode configuration was used with spacing arrangement of current electrode (AB/2) going from 1.5 to 250 meters and potential electrode (MN) 1 to 50 meters. The VES data was qualitatively analyzed by using iteration software (IPI2win) which showed that the area is composed of clay, shale, fractured sandstone with intercalation of clay based on resistivity contrast. At depth of 40m-100m along VES indicates good prospects for ground water potential, associated with sandstone beds of Siwaliks group. The resistivity depth section maps at potential depth of 30m, 40m, 60m and 80m are prepared for the demarcation of potential reservoir beds at various depth. The interpreted sounding curves are interpreted qualitatively and pseudo section, Resistivity section and geological log are prepared based on resistivity contrast which shows agreement with geology and hydrological condition of the area. The favorable reservoir rock as an aquifer demarcated in the study area is fractured sandstone with intercalation of clay beds, with apparent resistivity range of 80Ωm to 100Ωm and thickness of 20m to 50m at different sites. The apparent resistivity sections revealed that the North East (NE) and North West (NW) regions are comparatively good potential reservoir for ground water