Geophysical Characterization of Aquifers Using Vertical Electrical Sounding in Perumatty Panchayat, Palakkad, India

Abstract

Groundwater is an essential resource for drinking water, agriculture, and industrial use, particularly in regions where surface water is scarce. This study delineates subsurface aquifer configurations using the Vertical Electrical Sounding (VES) method to examine the hydrogeological features of the overfished Perumatty Panchayat in Kerala's Palakkad District. IPI2WIN software was used to evaluate the results of 13 VES surveys that were carried out over a 30.99 km² area using the Schlumberger electrode design. Three primary curve types were identified by the resistivity sounding: the H-type, K-type, and A-type. H-type curves indicate a shallow weathered zone overlying deeper, resistant bedrock, suggesting groundwater in fractures at greater depths, making deep wells more suitable. K-type curves represent a thicker weathered zone above compact bedrock, ideal for borewells due to its greater water retention. A-type curves show a conductive topsoil over a resistive weathered rock layer, making dug wells effective for tapping into shallow groundwater stored in the weathered rock. These types correlate to various aquifer conditions. The existence of lateritic topsoil, weathered zones, and basement rock strata was indicated by the 13 sites' 5 H-type, 5 K-type, and 3 A-type curves. Layer thicknesses ranged from 0.325 m to 11.43 m, while resistivity values ranged from 23.7 Ω-m to 43421 Ω-m, according to quantitative research. Aquifer potential varied spatially, with depth to foundation rock ranging from 2.68 m (VES 9) to 16.82 m (VES 5). Interestingly, VES 6 recorded an exceptionally low third-layer resistivity of 0.734 Ω-m, suggesting water-saturated zones, while VES 3 showed a second-layer resistivity of 43421 Ω-m, indicating a highly resistant compact rock. According to the study, fractured weathered zones favour borewells, especially in K-type and A-type curves, although H-type profiles suggest that dug wells may be possible. The effectiveness of VES as an affordable, non-invasive method for identifying aquifer structures in intricate geological terrains is demonstrated by this study. The results provide vital information for planning and managing groundwater resources sustainably in semi-arid and water-stressed areas.