There is a “new island” a Venicecalled “Bacan Island”a strip of land 260 meters long and 10 meters wide between the islands of Lido and Sant’Erasmo, perhaps also thanks to the presence of MOSESthe system of mobile bulkheads that protects the lagoon capital from high water. In reality, Bacan is not exactly new: before it was – in all probability – one sandbanki.e. an area of low, sandy soil typical of lagoons, which is periodically submerged by the tides. In short, it was a “temporary” island, visible above all at low tide, but which since 2020 has grown, consolidated and now seems to have become permanent.
Over time, salt marshes can evolve into stable islands, as in the case of Bacan, due to sedimentation phenomena which allow the structure to permanently rise above sea level and the vegetation to establish itself continuously.
From this point of view, Bacan already has one vegetation all its own, composed mainly of plants typical of humid and brackish environments, such as marsh reed (Phragmites australis), sea grass and other plants found in lagoon environments.
But why is there so much talk about it? The dynamics of consolidation are not yet very clear, but according to infrastructure technicians it would be due to MOSESthe Venetian system of mobile dams designed to isolate and protect the city and the lagoon from high waters and rising sea levels (for this reason, in particular, it cannot be defined as a “new” island).
However, an interesting debate has sparked among experts on this point. There have been many discussions related to the impacts of the system on the lagoon itselfand in particular on the salt marshes: some experts in fact claimed that the MOSE would have made them disappear (there are those who maintain that by blocking the natural flow of water and better regulating the entry of salt water from the lagoon, the accumulation of sediments is hindered) , while according to others it would have favored them, increasing the accumulation of sediments. The latter theory claims that the barriers would reduce the movement of the water and the dilution capacity, causing a greater deposition of sediments on the lagoon bed and leading to the formation of new areas that gradually emerge above the water level, as in the case of Bacan .
The studies in this regard are still ongoing, but the doctoral student’s research Davide Tognincarried out with teachers Luca Carniello And Andrea D’Alpaosso far they have shown that:
The salt marshes grow with storm surges and that the raising of the barriers protects the city, but inevitably reduces the sediment supply.
All the theories in this regard still need to be verified and counter-verified, and as some experts mention, it will be fundamental observatory (when the Lagoon Authority has been established) to allow the issue to be explored further.
