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Acqua Alta (high tide)

Even in high water events Venice is a city suitable for normal living:  in some periods of the year, the lower points of many fondamente (streets bordering canals), calli (streets), and campi (squares). Only very seldom are wide parts of the city flooded.
These floods are generally limited to a few centimetres of water, so that, usually, a pair of common Wellington boots is enough to overcome the problem. This contrasts with a misunderstanding common among those who do not personally know the matter and are lead to think, also by TV information, that acqua alta means water reaching to one's navel

Read the Frequently asked questions


 

 
 

Venice has taken and takes her reason of being , her greatness, her character of a unique city in the world from water; that is why being Venetian has always meant being part of this "waterhood", experiencing its positive sides and facing its specific problems without dramatising them.

High tide in Bacino San Marco


Among the problems typical of Venice the most evident derive from the water transport and traffic, and the discomforts caused by acqua alta. Acqua alta is nothing but a rather hefty high tide, such as often to flood, in some periods of the year, the lower points of many fondamente (streets bordering canals), calli (streets), and campi (squares). Only very seldom are wide parts of the city flooded.
These floods are generally limited to a few centimetres of water, so that, usually, a pair of common Wellington boots is enough to overcome the problem. This contrasts with a misunderstanding common among those who do not personally know the matter and are lead to think, also by TV information, that acqua alta means water reaching to one's navel. 

 
Acqua alta (high tide) in Piazza San Marco

It isn't obviously so: for instance, when "+100 cm acqua alta is mentioned, that metre only represents the increase in comparison with the average sea level (the average sea level conventionally accepted is the 1897 one measured at the Punta della Salute). At this level, only a very small number of city points get flooded. Acqua alta is due to a number of causes connected first of all with the astronomical tides and the geographic position of the Adriatic Sea, and emphasised by particular meteorological conditions. In addition to these there are local effects peculiar to the Lagoon, caused by winds, rains and, especially in the past, the contribution of continental fresh waters. 

 

 

During last century the Lagoon and its functionality were deeply modified by the action of man, who has, indirectly, contributed to magnifying the problem. Tide height is moreover subject to variations in relation with several meteorological issues. High tides get particularly huge when the barometric pressure undergoes a substantial decrease and/or there is a strong bora or scirocco (south-east) wind. The widest tide excursions usually occur at new and full moon periods (syzigies), in the first and last quarter of the moon (quadratures) the abundant high tide phenomenon is less likely to happen.







Typical high tide values in Venice during the period from 1923 to October 31, 1997.






 
 
maximum height
m +1.94
Nov. 4, 1966
minimum height
m -1.21
Feb 14, 1934
maximum range
m 3.15

maximum width of tide
from high to low

m 1.63
28 gen 1948; 28 dic 1970
maximum width of tide
from low to high
m 1.46
23-24 feb 1928; 25 gen 1966





 
 
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