Acqua alta (“High Water”, Venice), Venezia, Veneto, Italy
Exceptional tide peaks cause partial floods in Venice and other towns and islands in the Venetian lagoon. Most of these phenomena occur in autumn and spring, when the tides are reinforced by seasonal winds, as Sirocco, from South and Bora, from east.
To allow pedestrian circulation, the Majority installs gangways. Besides prior warning alerts to the population with displays and automatic phone calls and messages, intense forecast tidal events has announced by sirens.
The Acqua alta phenomena are ever-growing in the last decades.
A system of mobile darns, to prevent the tidal peaks, is under construction between the lagoon and the Adriatic Sea.
An exceptionally high tide (or acqua alta) on Sunday inundated %70 of the city of Venice. While the entire city struggles against subsidence, some areas are more at risk than others. This map, prepared by Virginia W. Mason and National Geographic Society, shows the areas of the city most at risk, 2009