It is a fascinating phenomenon that happens periodically in Venice. Acqua Alta (high water) refers to seasonal flooding that affects the city. It occurs usually between October and March and it is caused by a combination of factors (high tides occurring seasonally in spring and autumn; the rain in the mountains, flowing down the rivers into the lagoon; the rain in the lagoon; the wind blowing off the Adriatic and into the lagoon).
The high water can be a new and interesting experience for the visitors walking through the water in St.Marks Square (the lowest part of the city), but it’s a real inconvenience for the locals and also an indicator of the threat faced by the Venetian lagoon. When this phenomenon happens, the city installs a network wood planks along the main streets (called passerelle) to allow pedestrian circulation during the floods. This walkway system is generally set at 120 cm above the standard sea level.
However aqua alta is predicted and monitored. The city activates about 3 hours in advance when the Center predicted a very high tide (more than 120 cm). Further acoustic warning were given out as soon as it was possible to predict an exceptional tide (up to 140 cm). Nowadays sirens sound a first “await instructions” whistle to catch the population’s attention, then produce a sequence of whistles whose number increases with the expected tide level. When an event is forecast, the citizens are contacted by SMS (a free service provided by the municipality) to alert people about the floods.
For fashion lovers, a boot’s runway is happening on the passerelle when high water occurs. Water boots of all shapes and colours are common sight during this magnificent event.
By Claudia Arriaga