Seawater Intrusion Mitigation Through Nature-Based Solutions: A Comparative Study of Mazara (Italy) and Cap Bon (Tunisia) Aquifers

Seawater intrusion threatens coastal aquifers across the Mediterranean, where climate change and human pressures combine to undermine freshwater availability. The Mazara aquifer in Trapani (Sicily) and the Cap Bon coastal aquifer (Tunisia) exemplify this challenge: both experience progressive salinization as a consequence of groundwater overexploitation due to intensive irrigation, urban expansion and sea-level rise, amplified by semi-arid conditions and permeable coastal geology that facilitates saltwater migration inland.

The Sal-ACT project compares these two systems to understand shared drivers and site-specific differences in salinization processes and management responses. We combine field investigations, telemetered monitoring networks and hydrogeochemical modeling to characterize how seawater intrusion evolves spatially and temporally in each aquifer. Variable-density groundwater flow models then simulate different scenarios and test mitigation strategies under current and future climatic conditions.

A key innovation is the focus on nature-based solutions, particularly Managed Aquifer Recharge (MAR), as a sustainable alternative to energy-intensive desalination. MAR uses treated water to artificially replenish aquifers, diluting saline groundwater and increasing storage capacity while minimizing environmental impacts. Our comparative design explicitly addresses hydrogeological feasibility, water quality compatibility and potential risks from emerging contaminants, building on prior regional research on wastewater reuse. At the same time, beyond technical analysis, the project engages water authorities, farmers and local communities through participatory workshops to co-design context-appropriate solutions and strengthen adaptive governance.

This cross-border study is conducted within the Interreg Italy–Tunisia project Sal-ACT "Sea Water Intrusion mitigation in Tunisian and Sicilian coastal aquifers through innovative and green solutions", which aims to improve groundwater availability and quality in Cap Bon and Trapani through integrated monitoring, modeling, stakeholder engagement and nature-based mitigation measures.