Electrical methods for determining groundwater tables

As groundwater exploration (commonly referred to as well siting) is a prerequisite for carrying out water wells, geophysical survey work (electrical surveying) must be carried out to determine the location of the drilling site. Geophysical prospecting applied to hydrogeology plays an important role in the selection of sites for modern boreholes and wells by minimising the failure rate of these structures through the identification of areas most conducive to groundwater accumulation. Electrical prospecting is one of the geophysical methods used to study lateral and vertical variations in the apparent resistivity of the subsoil, ρa. To do this, a current of intensity I is sent into the ground via electrodes A and B, and the potential difference ΔV-produced by the Ohm's law effect-is then measured between two reference electrodes, M and N (quadripole configuration). Electrical prospecting is a method that enables the determination of the resistivities (the inverse of conductivity) of the ground, from which information can then be deduced.