Application of geoelectric method for groundwater exploration from surface (A literature study)

Groundwater utilization as a source of fresh water supply for various purposes in discharge area shows an ever to increasing trend, while land use of recharges also changes as development progresses. To meet its needs, many people rely on land-based exploration and exploitation. Groundwater is one of nature's most valuable and inseparable resources for life on earth. Groundwater exploration requires appropriate and efficient techniques. One commonly used method is the electrical resistivity method since, it is efficient and economical to determine groundwater. Vertical Electrical Sounding (VES) Method measurement of rock resistivity from the surface to determine the subsurface rocked layer [1]. Geoelectric resistivity is one of the variables which is the physical properties of the rock layers below the surface. Rock resistivity data can be used to develop a model of subsurface and stratigraphic structures in terms of electrical properties. Geoelectric resistivity depends on lithology, air content, porosity, and pore ions concentration [2]. Geoelectric method is divided into two parts: Mapping resistivity method as a resistivity method that aims to study horizontal variations of horizontal layer resistivity types and Resistivity sounding method or, the drilling resistivity method that studies the variety of rock resistivity beneath the surface of the earth vertically. Data processing of geoelectric measurement results can be done by standard curve method, 2-Dimensional method (Schlumberger and Wenner), 3-Dimensional Method (Configuration of dipole-dipole, Lee Partition Configuration, Rectangle Line Source, 3 Point Gradient System). Therefore, ambiguity in interpretation can occur and become indispensable for calibrating the geoelectric measurement data with available borehole data to establish the resistivity range of various lithology units. Resistivity data can be used to identify and describe subsurface features such as the presence and type of aquifers, contaminated groundwater, and sediment size distribution [3, 4, 5].