Geomorphic setting and related hydrogeological implications of the coastal plain south of the Venice Lagoon (Italy)

The contribution of the geological and morphological setting to the worsening or contrast of land subsidence and saltwater intrusion was pointed out in three areas located south of the Venice Lagoon (Italy): the littoral stretch of Chioggia, the southern lagoon margin (Punta Gorzone) and an inland sector of the lagoon drainage basin (the Zennare Basin). The main geological and morphological features were identified by sedimentological and geomorphic investigations. Saltwater intrusion, whose extent was indicated from geophysical investigations and analyses of water samples from wells, rivers, and channels, is related to the presence of sandy paleo-channels and a land elevation significantly below the mean sea level. At present, land subsidence, assessed by geodetic surveys, in situ evidence and topographical map comparison, is mainly caused by the drainage of cultivated peaty areas.