Application of Dipole–Dipole, Schlumberger, and Wenner–Schlumberger Arrays in Groundwater Exploration in Karst Areas Using Electrical Resistivity and IP Methods in a Semi-arid Area, Southwest Iran

Abstract

Cost-effective and efficient techniques of geoelectrics for groundwater exploration, especially in karstic regions, can be used to as an appropriate tool to recognition of karst hydrogeological potential. This paper provides a method based on the geoelectrical tomography to precise determination of the water well drilling location in karstic limestones of Izeh, southwest Iran. The geoelectrical operation done in 98 VES of Schlumberger and two profiles using dipole–dipole and Wenner–Shlumberger arrays. The 1D interpretation of VES using IPI2win followed by 2D electrical resistivity and induced polarization (IP) tomography using Res2Dinv in two sites, Naale Asbi syncline and the west of Izeh limestones, is carried out in order to propose the best locations for drilling of water wells. The results of the geoelectrical study of Asmari limestone of Izeh show the high electrical resistivity (between 200 and 1000 ohms-m) and low IP (lower than 3 Mv%V) indicates dry limestone, which decreases electrical resistivity (between 50 and 150 ohms-m) and stability in IP values, while the layers become water bearing. The dry cavities are characterized by very high electrical resistivity anomalies (ranging from 1500 to higher than 2000 ohms-m) with low IP values in the matrix of limestone with medium high electrical resistivity. The marl and marly limestone layers with low permeability can be detected by very low electrical resistivity (lover than 20 ohms-m) and high IP (higher than 10 Mv%V). The tomography of electrical resistivity and IP have strongly confirmed each other especially in the dipole–dipole array, and however, in some cases of Schlumberger array, the deviations are seen in the depth that can arise due to the high sensitivity of the IP data in high depths.