## 2 Study Area  
With a total surface of 550 km\({}^{2}\) and an average depth of about 1 m, the Lagoon of Venice is the largest Mediterranean lagoon and it is morphologically characterized by large extents of shallow areas (tidal and subtidal flats) and marshlands crossed by a complex network of tidal channels (Figure 1). Three inlets (Lido, Malamocco and Chioggia), with variable widths ranging from 350 to 900 m, and depths ranging from 7 to 20 m, ensure water exchanges with the Adriatic Sea, which are driven by a semidiurnal tide with an excursion of about 1 m in spring conditions [20]. Wind can also have a considerable effect on water circulation and exchanges during extreme meteorological events [36]. Two prevailing wind directions are present in the area: northeasterly (Bora), more frequent in winter storms, and southeasterly (Sirocc) more typical of autumn/spring periods [37]. The circulation in the open sea by the Venice Lagoon is characterized by specific patterns generated by the interaction between the coastal current and local tidal dynamics at the inlets [38]. In this context, the Lido inlet (Figure 1, subset A) is a key area within the complex of interactions between the lagoon and the open sea. Two large tidal channels, about 400 m wide, originate from the inlet channel, namely Treporti and San Nicolo (TRP and SN in Figure 1). The two channels are 15 and 7 m deep, respectively, and drain a sector of the lagoon where half of the total water discharge and solid load is vehiculated by the largest tributaries of the drainage basin [39; 40]. According to [25], the negative sediment budget of the lagoon is currently dominated by the loss from the Lido inlet, possibly due to the contribution from the input of lagoon tributaries and the erosion of marshlands and tidal flats that still occupy large areas in the northern basin. On the other hand, occasional inputs of marine sediments can be driven by tidal inflow during storm events, when sediments, resuspended and moved by longshore current along the Northern Adriatic coast, are transported and deposited on the flood tidal delta and in the more distal lagoon sectors.  
Starting from the end of the 19 th century, the morphology of the Lido inlet has been subjected to large modifications when jetties were built to stabilize the port channel joining the three preexisting tidal inlets in a single 900 m wide artificial entrance. In the last few decades, the construction of the MoSE system introduced further modifications. On the lagoon side, an artificial island was built at the junction of the TRP and SN channels. The island hosts the buildings of infrastructures to operate the two arrays of barriers, which are hosted in a concrete housing on the seafloor on both channels. On the sea side, at the south of the inlet entrance, a breakwater was successively built, increasing the complexity in the pattern of inflow circulation and outflowing tidal jets [32]. On the northern jetty, a partial restriction of the inlet channel was created to host a navigation lock and two refuge harbors for the transit of boats during the closures of the MoSE mobile barriers. The overall restriction of the inlet channel cross-section increased the current velocities and induced local changes in the inlet sedimentary regime with a transition from depositional to erosive and a net sediment loss in the area of about 612 \(\times\) 10\({}^{3}\) m\({}^{3}\)[31].