Saltwater contamination in the lowlying coastland of the Venice Lagoon, Italy

The southern portion of the Venice coastland includes a very precarious environment. Due to an elevation down to 4 m below msl, the Venice Lagoon and Adriatic Sea proximity, and the encroachment of seawater from the mouth of the river network up to 20 km inland, salt contamination of land and groundwater is a severe problem that is seriously affecting the farmland productivity. An interdisciplinary multi-scale research is ongoing with the aim of understanding the contamination process, quantifying the effect of the saltwater intrusion of the crop production, and proposing possible mitigation strategies. A 21-ha representative basin has been selected and deeply monitored from the hydrogeological and agricultural points of view. It has been clearly outlined that in the upper 5 to 10 m mainly the low-permeable soils are contaminated by salt. Conversely, fresh to brackish waters are located in the sandy elongated paleo-channels. This is likely due to the origin of the area which was a salty marshland since one century ago. The freshwater supplied for almost 100 years by the rainfall and leakage from the river and channel beds has been able to reduce the salt concentration only in the highly permeable deposits.