Assessment of Hydraulic and Geoelectric Parameters of the Aquifers and Their Relationship Using Vertical Electrical Sounding in Gurpur Watershed, West Coast of India

Abstract

The investigation of the nature of subsurface formations by studying the variations in their electrical properties is the electrical resistivity method. 35 Vertical Electrical Soundings (VES) are conducted using a four-electrode Schlumberger array (1-D arrangement) with an electrode spacing (AB/2) separation up to 200 m. The Inverse Slope Method (ISM) is used for data interpretation. The computer iterative java supported software ATS 3.0 is used to process the data. Based on the obtained results, the hydraulic and geoelectric parameters are inferred. The overall layer resistivity values of all the layers are found to be in the range of 14 Ωm (VES 3)–7958 Ωm (VES 31). The overall thicknesses of the geoelectrical layers are found to be in the range of 1.3 m (VES 23)–76.2 m (VES 11). The depth to bedrock varies in the range of 3.7 m (VES 2)–44.4 m (VES 10). The aquifer thickness (h) varies from 19.5 m (VES 19) to 149.5 m (VES 15). The average values of Porosity, Hydraulic Conductivity, and Transmissivity are 28.4%, 0.23 m/day, and 15.9 m²/day, respectively. The correlation of hydraulic conductivity (K) with the porosity ($\emptyset$), transmissivity (T), longitudinal unit conductance (S), and aquifer anisotropy (λ) shows a positive correlation (>0.7). The correlation of K to layer resistivity ($\rho_{0}$) and transverse unit resistance (TR) shows a good but negative correlation (< −0.7). The T shows a good correlation with S, λ, and K but a moderate correlation with $\emptyset$ and Formation factor.