Saltwater intrusion and soil salinization in coastal farming systems: a case study of Roman coastal area

Saltwater intrusion and soil salinization are emerging as major threats to coastal agricultural systems worldwide, particularly in Mediterranean lowland and reclaimed areas where freshwater availability, soil fertility, and crop productivity are tightly coupled. Climate change–driven sea-level rise, increasing frequency of drought events, and intensified irrigation withdrawals are progressively altering the hydrological balance of coastal plains, promoting the inland migration of saline waters and the accumulation of soluble salts in agricultural soils. These processes determine long-term risks to crop yields, soil health, and the sustainability of food production systems. Despite the growing attention to these processes in Mediterranean environments, a clear knowledge gap has persisted in the Roman coastal plain, where integrated and field-based information on soil salinity and its seasonal dynamics in agricultural systems has been largely lacking. In response to this absence of site-specific and systematic analyses, the present research was designed to provide a first comprehensive baseline of salinization processes in this area. The investigation adopts an integrated approach to analyze the spatial and temporal dynamics of saltwater intrusion and soil salinization in a reclaimed coastal agricultural area of central Italy, located within the Roman coastal plain (Fiumicino–Maccarese sector). Soil texture was first assessed to evaluate the intrinsic vulnerability of the study area to salinity. Soil electrical conductivity was subsequently monitored using time-domain reflectometry (TDR) and leachate extraction techniques. In parallel, the electrical conductivity of surface and irrigation waters was measured along the Tiber River and within the reclamation canal network to investigate the potential role of saline water sources in driving soil salinization. These datasets were analyzed in relation to seasonal climatic patterns and hydrological conditions. The results highlight pronounced seasonal variability in salinity, with critical increases during summer months associated with reduced freshwater availability, high evapotranspiration rates, and irrigation demand. Differences among sampling points reflect the combined influence of soil texture, proximity to surface water bodies, and hydraulic management practices. This research emphasizes the importance of continuous monitoring and integrated assessment for the early detection of salinization processes. The findings support the development of preventive and adaptive management strategies aimed at safeguarding soil fertility, irrigation water quality, and the long-term sustainability of coastal agricultural systems under ongoing climate change.