Hydrogeophysics techniques for the characterization of a heterogeneous aquifer

The target of this work is the determination of hydraulic conductivity spatial distribution in a real aquifer using a hydrogeophysical approach. This was made possible by analyzing geoelectrical data coming from “cross-hole” electrical resistivity tomography. The geophysical techniques most used in hydrogeological studies are the geoelectrical methods because electrical resistivity is very sensitive to the presence of water. Since the electrical resistivity strongly depends on some hydraulic parameters such as porosity, water content and hydraulic conductivity, several relationships have been developed in order to estimate these hydraulic parameters using the measured electrical resistivity values. In this work, we present an experiment carried out at the Montalto Uffugo test site (Cosenza, Italy) of University of Calabria, where we determined the spatial distribution of hydraulic conductivity using a geoelectrical technique with electrodes located in two boreholes. The crosshole electrical resistivity tomography (ERT) allowed us to obtain the resistivity distribution in the subsoil and compare it with the geological-stratigraphic information obtained through the analysis of two cores. Then, the data acquisition with the ensuing elaboration led to the characterization of the main aquifer of Montalto Uffugo and the reconstruction of the hydraulic conductivity distribution in the subsoil applying Archie’s Law and Purvance and Andricevic’s Law. The estimated hydraulic conductivity compares favourably with values previously determined in situ by some hydraulic tests.