Coastal freshwater resources are commonly under high risk of being contaminated from seawater. The main processes that affect seawater intrusion are groundwater overexploitation, land use change, and climate change effects. In this context coastal lagoons represent the more sensitive environments prone to seawater intrusion. Numerical modelling is a useful tool to understand and predict seawater intrusion. In this study, a three-dimensional SEAWAT model is employed to simulate the seawater intrusion to coastal aquifers of Variconi Oasis (Italy). The present simulation was divided into a calibration and a validation model, then the model was used to predict the salinization trend up to 2050. Results show the role of the sea in salinizing the beach front, while the retrodunal environment is characterized by transitional environments. Future seawater intrusion scenarios considering only climate data showed no significative differences in respect to the actual situation. The same happens considering also a low sea level rise prediction. On the contrary, the worst scenario (high sea level rise prediction), depicts a quite different situation, with a saline intrusion in the Variconi oasis that will severely affect the fragile transitional ecosystem. This modelling framework can be used to quantify the effects of climate changes in similar coastal environments.

The Volturno Plain is one of the largest alluvial plains of peninsular Italy, which is one of the most susceptible plains to coastal hazards. This area is characterized by both natural and human-induced subsidence. This present study is based on the post-processing, analysis and mapping of the available Persistent Scatterer interferometry datasets. The latter were derived from the combination of both ascending and descending orbits of three different radar satellite systems during an observation period of almost two decades (June 1992–September 2010). The main output of this study is a map of vertical deformation, which provides new insights into the areal variability of the ground deformation processes (subsidence/uplift) of Volturno plain over the last few decades. The vertical displacement values obtained by the post-processing of the interferometric data show that the Volturno river plain is characterized by significant subsidence in the central axial sectors and in the river mouth area. Moderate uplift is detected in the eastern part of the plain, whereas other sectors of the study area are characterized by moderate subsidence and/or stability. On the basis of the analyzed subsoil stratigraphy, we inferred that the subsidence recorded in the Volturno plain is mainly a consequence of a natural process related to the compaction of the fluvial and palustrine deposits that form the alluvial plain. The anthropic influences (e.g., water exploitation, urbanization) are substantially considered to be an additional factor that may enhance subsidence only locally. The uplift mapped in the eastern sector of the plain is related to the tectonic activity. The study of the subsidence in the Volturno plain is a valuable tool for river flood analyses and the assessment of the coastal inundation hazards and related risk mitigation.