Geoelectric Tomography and Electrical Methods, with Applicability in the Strategy for Identifying Contaminated Area

Abstract

In this article, we would like discribing the technique underlying the investigations through computed geoelectric tomography done using the resistivity method. The method is designed to reveal information about those formations or bodies which display anormalies of the electrical conductivity and also has long been used to diferentiate the layers that have different levels of conductivity. Apparently these resistivities are usually functions of some variables which are in accordance with the depth of the investigation. The geological surveillance utilizes a wide variety of techniques, each based on different properties or characteristics of the soil. It is accoustomed for most electrical methods to define a function called the apparent resistivity response [ρa], which can be assessed and estimated from measurements. The giding principle of the method - The data collection is made uniformly throughout the profile,the density being determined by the distance between the electrodes and the type of the chosen device. Through one single stretch of the cable we can perform hundreds of multi-electrode measurements of resistivity, and thereby creating a 2D image of the sub-soil similar to a tomography. The data is then filtered and processed using a specialized software, which, unlike the Vertical Electric Survey method (SEV), performs a 2D inversion of all sections according to the lateral variations of the resistivities'-distribution throughout the length of the profile.