Temporal evolution of a coastal aquifer in presence of seawater intrusion: the case of Sibari plain (Southern Italy).

The aim of this paper is to present the modeling of a coastal porous aquifer located in the plain of Sibari (Southern Italy) to establish the effect of seawater intrusion since the well discharge was negligible (natural conditions), to current overexploitation. Qualitative and quantitative groundwater trends from 1930 to 2000 were so defined. This temporal evolution of groundwater resource will be used for forecasting purpose and for evaluate new management tools for a sustainable use of water resource. Study area is about 365 km2 for a coastline of about 35 km. The area can be conceptualized into three hydrogeological complexes (from the top): Sand and Clay, Clay and Silt, Sand and Conglomerate, this last constituting the deep confined aquifer, the bottom of which is not well-defined. Shallow aquifer is predominantly fed by direct rainwater infiltration. Deep aquifer is fed by outflows of the mountainous aquifers as the case of limestone aquifer of Pollino Mount and of shallow granitic aquifer of the Sila massif. The computer codes selected for numerical groundwater modelling were MODFLOW and SEAWAT. Model was calibrated with PEST code with a correlation coefficient equal to 0,90. The water balance of both aquifers was calculated. A relevant decrease of piezometric surface and increasing effects of seawater intrusion were observed in the shallow aquifer. Low modification of piezometric levels and salinity were observed in the deep aquifer. These preliminary results and next result scenarios will be used together with on-going survey data to assess trend of future groundwater availability and quality.