The first operations of Mo.S.E. system to prevent the flooding of Venice: Insights on the hydrodynamics of a regulated lagoon

In October 2020, for the first time in its thousand-year-old history, the Venice Lagoon has been temporarily closed. The first operations of the Mo.S.E. system, a set of artificial barriers built to isolate the lagoon from the sea in case of high tides, prevented Venice and the other lagoonal settlements from flooding. Beyond its historical value, the closure of the lagoon inlets has led to unprecedented scenarios from a hydrodynamic standpoint. With the Mo.S.E. system operational, significant high tides can no longer be recorded within the lagoon and the undisturbed tide propagation can only be estimated through hydrodynamic modelling. When the inlets are closed and the effect of tide propagation nullified, the action of wind on cross-lagoon setup is enhanced and becomes more clearly recognizable, allowing for a robust calibration of the wind drag coefficient also for low to moderate wind speed. Furthermore, the data collected during the first closures of the Mo.S.E. gates allowed evaluating the real intra-gate infiltration entering the lagoon through the closed gates, and suggested that the gate operation produces some seaward disturbance as well.