A geophysical and geochemical approach for seawater intrusion assessment in the Acquedolci coastal aquifer (Northern Sicily)

Vertical electrical sounding (VES') surveys and chemical analyses of groundwater have been executed in the coastal plain of Acquedolci (Northern Sicily), with the aim to circumscribe seawater intrusion phenomena. This urbanized area is representative of a more general problem interesting most of Mediterranean littoral areas, where intensive overdraft favors a heavy seawater intrusion through the coastline. Aquifer resistivity seems decisively to be conditioned by the chlorine and magnesium content in the main aquifer of the region. Schlumberger VES', together with piezometric and chemical-physical information of groundwater, allowed us to perform hydrogeological and geophysical elaborations, to propose the occurrence of a relatively narrow belt marked by fresh-salt water mixing. In the considered plain, pollution risk studies have been already realized by authors with the proposal to identify-by parametric and synthetic zoning of significant hydrogeological elements-the most vulnerable sectors. In detail, an intrinsic vulnerability mapping has been already performed, applying the well-known SINTACS system. This paper intends to give-in this sector of Sicily-an example of integration of different methodologies, showing the role of geophysics to describe the degradation of aquifers on the whole as well as to assess their pollution risk better.