Analysis of salinization processes in the coastal carbonate aquifer of Porto Torres (NW Sardinia, Italy)

SummaryThe Porto Torres (NW Sardinia) coastal aquifer is hosted in the carbonate rocks of the Miocene succession, which fills a NNW oriented half-graben. This aquifer is an important contributor to the fresh water supply of the local area. It is increasingly being degraded by salinization processes, mainly associated with intense groundwater over-exploitation. A combined hydrochemical and hydrogeological study has been carried out to identify the origin of the salinity in the groundwater. The behavior of the major ions showed that the changes in the chemical composition of the groundwater have been mainly controlled by the encroachment of seawater, accompanied by cation exchange reactions. Since seawater intrusion is a dynamic process, an Hydrochemical Facies Evolution Diagram, HFE-D (Gimenez Forcada, 2010) approach was taken to establish whether the aquifer was in the seawater intrusion or in the freshening phase. The assessment model developed provides regional authorities with a basic tools for sustainable water management in the framework of multi-disciplinary research activities aiming to combat and/or mitigate desertification and land degradation processes.

► We study the salinity processes in a aquifer using hydrochemical data. ► We study the sea-water intrusion process using the HFE-D method. ► We identify the phase, the evolution and dynamics of the saline front. ► We identify the existence of ionic exchange between the saline water and the aquifer.