Hydrogeological model development for scenario analysis of climate change impacts

Seawater intrusion, a critical environmental issue in coastal regions globally, depletes freshwater resources. This contamination also degrades soil, potentially limiting land use or leading to abandonment. To mitigate future salt intrusion, this study develops a model simulating its evolution under climate change, incorporating declining recharge. For this purpose, two codes have been coupled: IMOD and SWB. To simulate the coupled effects of groundwater density and solute transport, it utilizes iMOD-WQ code developed by Deltares. iMOD-WQ incorporates SEAWAT, a well-established tool for modeling density-dependent interactions between freshwater and saltwater in aquifers. While iMOD offers a graphical user interface, Python scripting was chosen for this study due to its superior data manipulation capabilities. A Soil Water Balance code was used to quantify the impact of climate change on natural recharge. This code, implemented by the USGS, allows the variation of recharge to be simulated in both time and space. In addition to climate data, the code is based on soil characteristics. Four inputs are needed: land use, available water capacity, hydrological soil group and Flow direction. This study focuses on the coastal plain of Muravera (Sardinia, Italy), where seawater intrusion has negatively impacted both the environment and the local economy for over five decades. Leveraging a comprehensive dataset, all model inputs are derived from long-term field measurements. This approach significantly contributes to water resource management by facilitating the development of effective strategies to mitigate salt intrusion under future climate change scenarios. Its applicability to other coastal regions enhances its value as a tool for broader water resource protection.