The phenomenon is locally known as acqua alta.
This coincidence happens from about the middle of October to the beginning of December.
Since, acqua alta is a tidal phenomenon, it lasts three to four hours, during high tide.
Once water goes down again, things go back to normality.
The flooding triggered by the acqua alta is not uniform throughout the city of Venice.
A city-commissioned study showed, a tide up to 90 cm.
above sea level leaves Venice virtually unaffected, while 50 cm.
of additional water hit more than a third of the city.
The municipality runs a service notifying residents of the potential danger.
Acqua alta causes very limited inconvenience to Venetians and tourists.
Otherwise, grabbing a pair of cheap rubber boots is recommended.
Photo credit
Sources:Wikipedia,Fodors,Venezia.it
