Identification of Areas Vulnerable to Salinisation in a Coastal Aquifer of Western Sicily (Southern Italy) within the Framework of the Water Body Status Update

As of December 19, 2025, Sicily Island is under a water crisis emergency due to severe and prolonged drought. Monitoring conducted by the Permanent District Observatories, utilising indicators such as the Standardised Precipitation Index (SPI) and saline intrusion data, confirms a critical level of water scarcity, necessitating extraordinary management measures. Current water resource management in Sicily requires updating the status of groundwater bodies, for which a comprehensive framework is presently lacking; to address this gap, Sicilian Universities and the Sicilian River Basin District Authority are collaborating to update the regional’s hydrogeological framework. In this context, the University of Palermo is currently characterizing the aquifers of Western Sicily. These can be grouped into three main categories: carbonate aquifers, alluvial aquifers (river valleys), and porous aquifers in calcarenitic rocks (coastal plains). The latter are highly productive shallow aquifers, easily accessible via wells often only a few tens of metres deep. The study focused on the 286 km² coastal plain aquifer of the Marsala-Mazara coastal plain, which is characterised by intense urbanization, a strong tourism sector, diversified agricultural activities (encompassing general and greenhouse farming as well as viticulture), and aquaculture. As part of the collaboration-which involves creating hydrogeological databases, redefining groundwater body geometries, updating hydrogeological data, and implementing a monitoring network-hydrogeochemical and groundwater data were updated using both historical and recently surveyed wells and springs. The aquifer's shallow depth and proximity to the coastline render it extremely vulnerable to both nitrate pollution (intensive agriculture) and saline intrusion, which is driven primarily by excessive groundwater abstraction—often unauthorized—and is exacerbated by climate change. Drought conditions impede winter aquifer recharge, while torrential rainfall events favour surface runoff over infiltration. The resulting decline in piezometric levels allows the saline wedge to advance inland. Furthermore, geochemical interactions between saltwater and the calcarenitic matrix promote ion exchange and the resulting release of specific ions, compromising water quality for irrigation and increasing the risk of soil desertification. The new hydrogeological characterisation of the Marsala-Mazara water body and the and the implementation of the monitoring network allowed updating of the hydrogeological and hydrogeochemical characteristics as well as their temporal evolution through the comparison of historical and recent data, including climate data. Surveys have allowed the identification also of high electrical conductivity values in numerous coastal wells and the identification of the most vulnerable zones, which are now subject to in-depth analysis to define concrete strategies for aquifer recovery and salinisation mitigation.