Sustainable groundwater management in coastal areas: Modelling saltwater intrusion dynamics in Muravera, Italy

Abstract The coastal alluvial aquifer of Muravera, in south-eastern Sardinia (Italy), is affected by intense saltwater intrusion that seriously threatens freshwater supply. As groundwater overexploitation is often the main process controlling saltwater intrusion dynamics, it can strongly exacerbate salinization, making sustainable groundwater management essential to safeguard these resources. Reliable hydrogeological models based on robust datasets are powerful tools to support decision-making. This work develops a variable-density groundwater flow and solute transport model to analyse saltwater intrusion into the coastal aquifer of Muravera. Four simulation scenarios were implemented. The first reconstructs the historical evolution of salinization over the period of 1999–2023, whereas the other three extend the simulations to 2050 to quantify the various effects of different groundwater abstraction practices and to test a mitigation scenario. Two modelling codes were coupled to support the analysis. Groundwater recharge was computed using the Soil–Water-Balance (SWB) code and subsequently used as input to the iMOD-WQ code, which simulates variable-density flow and salt transport using SEAWAT. This coupling explicitly captures temporal and spatial recharge variability, which is often oversimplified in other approaches. The results indicate that groundwater abstractions for rice-field irrigation exerts a stronger influence on salinization dynamics than drinking-water abstractions. The mitigation scenario attenuates groundwater salinization in the plain, providing useful insights for future groundwater-management strategies.