9. Assessing the Vulnerability of Groundwater Pollution at Sensitive Areas by Geophysical Methods

The protection of groundwater has became one of the foremost environmental European policies according the Orders on the Protection of Water Against Contamination Directive 2000/60/CE of the European Parliament and the European Union Council, and more concretely with the Directive 2006/118/118/CE, related to groundwater protection against the pollution and degradation. Traditional methods for assessing vulnerability include soil surveys, drilling and analyses of logs from wells with the objective to characterize the thickness, hydraulic properties and lateral extent of the protective layers. Disadvantages of such investigations are that they can be labour-intensive and expensive. In addition, the measured parameters may have high spatial variability making accurate characterization over large areas difficult. As a result, a numerical index of protection can be assessed from the longitudinal electrical conductance parameter derived from electrical resistivity surveys (VES, ERT or any other electrical or EM method), that can be more accurate and reliable than any other vulnerability index assumed only by visual inspection or interpolated from sparse borehole data.