SALTWATER INTRUSION IN A UNCONFINED COASTAL AQUIFER: THE CASE STUDY OF CERVIA ( NORTH ADRIATIC SEA, ITALY)

The coastal freatic aquifer of the Cervia city is polluted by salt water. Protection of fresh groundwater resources in this area is complicated by the presence of multiple stakeholders and by the fragmentation of the authorities responsible for land planning. Most of the topography is under sea level or in its close proximity. Consequently, most of the aquifer does not have a hydraulic head able to prevent the intrusion of the salt wedge at its base (Ghyben-Herzberg principle). Water table and salinity maps show an aquifer almost completely invaded by salt water with bubbles of surface fresh water almost completely confined to elevated areas located near the coast. The study identified as causes of salt water intrusion: direct contamination from canals open to sea, subsidence, drainage of farmland, groundwater extraction from wells along the shoreline (bathing establishments) and, last, groundwater winning from private wells inland. On the basis of these results some mitigation action can be proposed: the lining of the salt canals, a different management plan for the floodgates on the canals, to provide shoreline establishments with freshwater from other fresh water resources as a measure to stop direct tapping from the aquifer.