On Monday this week acqua alta (high water) reached 156 cm above its normal level in Venezia, creating a lot of damage and discomfort to the city and its population. The whole of the lagoon was flooded and the passerelle (gangways), which are normally set up to allow people to walk on in the event of a flood, were floating. Shops and ground floor businesses were invaded by the murky water, and rubbish and other objects were washed away, while gondole and vaporetti (ferries) could not travel. There are some photos of the flood on this page of the Italian newspaper Corriere della Sera.

This is not a very romantic image of Venezia, but it is reality, a reality that its citizens have to live with due to the unique nature of Venezia, which is built on a series of islands just above sea level. Because of its shape the Adriatic Sea, on the coast of which the city is located, is subject to greater sea tides than the rest of the Mediterranean. If we add to this the heavy rains of the past few days and the strong winds that drive the seawater inside the lagoon and prevent it from returning to the sea again, we get a very dramatic situation. There are also other factors, both natural and man-made, that contribute to the problem of the acqua alta, such as the fact that since 1897 (the year of the first official measurement) Venezia has sunk by 23 cm, and that the industrial area of Porto Marghera was built by reclaiming land from the sea. Originally Marghera was an area of very low islands, which allowed the water to flood over them, working like an expansion tank for the lagoon.

Theoretically these floods could be prevented by a pneumatic barrier system called MOSE (Modulo Sperimentale Elettromeccanico), designed to isolate the lagoon from the sea in the event of a combination of an exceptionally high tide and extreme weather. However the works, which were begun in 2003 with a planned completion date of 2012, have been criticized by environmentalists because of the ecological impact that they are having on the wildlife of the lagoon. For more information about this project see: http://en.wikipedia.org/wiki/MOSE_Project