Acqua Alta is a famous Italian word that norther people know well, it means “high water” and it is used in the Adriatic north coast to indicate high tides. Indeed this Mediterranean region is more at risk than other parts, this becau ts particularly rectangular shape and Venice, is the city more affected by this calamity. One of the most dangerous thing that can increase Acqua Alta is wind; in fact the northbound winds called Bora and Sirocco often blow directly towards the harbours increasing tides.

The worst tide has been detected on 4th November 1966 reaching the incredibly number of 194cm, while on 12 November 2019 this record was almost broken by 187cm, but it did not stop; other tides arrived in Venice day after day, giving no respite to Venetians.

In 2007 Venice has created an alert system to face this problem; it consists of a siren that warns the people, anticipating Acqua Alta. This siren works with a frst sound used for catching the population's attention, then it produces a sequence of whistles whose number increases with the expected tide level: frst tone is for 110 cm, second for 120 cm and so on. When the tide is in a range between 180cm and 190 cm the 82,40% of the Venetian roads are fooded, meanwhile if the food reaches 200cm it would be 100% of them.

Actually many studies explain that Venice will sink in 80 years, turning it into an underwater city; scientists are expecting that sea level will rise up by 140cm, but water level is growing faster, as a result of increased concentrations of greenhouse gasses, which raise the temperature of the earth’s atmosphere.