Integrated hydrogeochemical and geophysical surveys for a study of sea-water intrusion

The CFTA Department of the University of Palermo in collaboration with ARPA SICILIA has carried out a study of the sea intrusion phenomenon in the aquifer between the cities of Marsala and Mazara del Vallo (south-western Sicily) using geophysical techniques (TDEM, ERT and MASW) and geochemical analysis of well water. The aim of the research was to optimize the acquisition techniques, data processing and data interpretation for the geometry reconstruction of aquifers, their characterization, and the determination of concentration of pollutants. The analysis of the geophysical results reveals the existence of very low resistivity values in correspondence of the area from the coastline to a kilometer inland. Obviously, in this area, the sea intrusion is more pronounced. Furthermore, major element contents and physical-chemical parameters of sampled water testify that the main process that defines the groundwater geochemistry in this area is a mixing between the carbonatic aquifers and the marine component. A significant contamination of nitrate and sulphate is also present. About 90% of the sampled wells were contaminated over the Italian legislation limits.