Conceptualization and characterization of a coastal multi-layered aquifer system in the Taranto Gulf (southern Italy)

In some Mediterranean karst areas, groundwater is often the only available supply for fresh water. Besides the contamination induced by human activities, coastal aquifers often suffer from the saltwater intrusion phenomenon, which can be enhanced by both extensive withdrawals and climatic changes. Establishing an effective set of regulatory and management measures to ensure the sustainability of coastal aquifers requires a deep knowledge about natural and anthropic stresses involved in groundwater dynamics. In this regard, a prior conceptualization of aquifer systems and a deeper characterization of balance terms through mathematical modeling are of paramount importance. In this paper, previous works on the three-dimensional hydrostratigraphic characterization and two-dimensional groundwater flow modeling at the regional scale for the Salento peninsula (southeastern Italy) are shown to provide a fundamental basis for an overall conceptualization of the multi-layered aquifer system of the Taranto Gulf (northwestern Salento). This is done by identifying source terms and providing a preliminary estimate of different balance terms, based on available data and information. Then, a further characterization will be provided using three-dimensional groundwater flow models and calibration techniques based on the solution of an inverse problem. As a result the hydraulic features of the deep karst aquifer can be mapped; the stresses due to human water-demanding activities and the occurrence of the saltwater intrusion phenomenon were analyzed and possible weaknesses of the conceptual and of the preliminary numerical model pointed out.