Predicting long-term settlements of coastal defences for the safeguard of the Venetian Lagoon.

Over the last decades, a number of engineering solutions, including both nearshore and offshore structures, have been designed in order to protect human activities of the whole Venetian coastal environment as well as the invaluable historical and artistic heritage of Venice (Italy) from sea storms, high tides and recurrent flooding. In recent years, in the context of the ambitious mobile barriers system project known as MOSE, the existing jetties were extended and new breakwaters were set up in front of the three inlets connecting the lagoon to the Adriatic Sea. In order to preserve integrity as well as effectiveness, a key issue in the design of such structures is represented by the estimate of both short-term and especially long-term settlements. Indeed, field observations as well as laboratory evidence have shown that time-dependent phenomena cannot be considered as negligible in the predominantly silty sediments forming the Venetian lagoon basin. This paper focuses on the prediction of the long-term response of Venetian coastal defences, using a one-dimensional settlement method in conjunction with a C(alfa-epsilon) profile determined by piezocone tests and based on a formulation recently calibrated on field data from a Test Site located in the Venetian lagoon area.