The Arrival of Autumn
|Acqua alta, Piazza San Marco|
|Hydrographic station, Punta della Dogana|
Acquae alte are officially categorised as:
Marea sostenuta (80-109cms)
Marea molto sostenuta (110-139)
Alta marea eccezionale (140+)
An acqua alta of only 80 cms is enough to flood the lowest parts of the city, which also happen to be the busiest, namely the Piazza San Marco and the Basilica. In recent years the frequency of acquae alte has increased considerably. In 2014 there were 189 compared with only 35 in 1983.