Application of Electrical Resistivity Method for Assessment of Groundwater Potential in Semi-Arid region with Basalt Landform

Abstract

The assessment of groundwater potential should be done, considering the aquifer properties .Hence, to study the layer properties, electrical resistivity method has to be deployed. In the current study, the application of electrical resistivity method for assessment of certain properties of aquifers in hard rock terrain has been discussed. The test is carried out using Schlumberger method with four electrode configuration, at 15 test sites, near to the drainages, covering different litho unit’s representatives. Data obtained from the test, was analysed in IPWIN-12 software. The graphs of the test show, 3 to 6 layers presence below ground level. Few curves of H type which is groundwater potential curve and few curves show A type which is hard rock terrain curve. Fractures are found at 40 meters to 50 meters depth and weathered basalt and jointed basalt are found between 15 meters to 25 metres depth below ground level and these are considered as good aquifer systems. Top overlain soil thickness ranges from 3 meters to 5 meters. For the assessment of saturated aquifer thickness, Daroo-Zarrok parameters are used. It is found that, the longitudinal conductance varies from 0.6 per ohm to 4 per ohm. The eastern side and western side of the study region have 3 to 4 per Ohm of longitudinal resistance, which represent fresh groundwater potential in these zones at depth 5 meters to 12 meters. For assessment of aquifer depth and thickness of overlain layers, 2D pseudo-electric cross sections are developed in IPWIN-12 software. The obtained results from electrical resistivity test, were verified with trail boreholes data at 3 locations and it was found to that, the observed stratum types and obtained results of resistivity test are analogues.