The infamous great flood, that hit Venice in 1966 was mainly caused by the local phenomenon called ‘Acqua Alta’, which every year occurs in the Venetian Lagoon, fortunately on much lower scale.
Acqua Alta (”High water”) is the period of abnormal level of sea water in Venetian Lagoon, which rise due to coincidence of several factors – scirocco (warm south-east wind blowing towards the Lagoon) and seiche ( a sort of long wave which periodically washes all Adriatic coasts ).
When the sea level is roughly 1 m higher than normal, during the high tide the water floods onto the streets of Venice, to step back during the low tide.
As the tides change every 6 hours, so the ‘acqua alta’ in the city lasts only couple of hours, during which one can stay at the hotel, or walk carefully wearing famous rubber ‘acqua alta boots’, in several places are placed temporary ‘footbridges’ , allowing pedestrians to walk dry. The public waterbuses keep working, but there may be some temporary route changes.
Located near the Santa Maria della Salute Church, special point ‘Punta della Salute’ marks the median ‘zero’ level of water.
More than 90% of Venice is +100 cm above the ‘Salute Point’ level, thus only the tides over 110 cm high are visible in the city.
High waters are most likely to happen in November and December, and statistically they occur 4 times a year. The exceptional high waters may happen once every 5 years.
The population is warned in advance, when the weather forecast the sea level above 110 cm, and the local informations are found
at the following address
www.comune.venezia.it
Guides: venice
