The waterways of Venice attract millions of visitors from around the world every year – but rising floodwaters have overwhelmed the Italian city.
Here we explain why Venice has flooded, what defences there are, and if the city is sinking.
Why does Venice flood?
Venice experiences a phenomenon “acqua alta” or “high water” due to exceptional tide peaks in the Adriatric Sea.
The tidal peaks reach their maximum level in the Venetian Lagoon, which runs around and through the city, causing flooding in the region.
The causes of the tidal peaks are down to a number of factors, including the movement and phase of the moon, wind strengths and direction as well as rain level and rising sea-levels.
The flooding levels vary across the city due to varying altitudes above sea level, plus heights of pavements and distance from channels.
Is Venice sinking?
According to LiveScience, the rise in sea-level isn’t the only thing that has Venice’s famous canals rising every year because the city is subsiding.
Previous studies had suggested the city’s subsidence had stabilised but it has been claimed that the city is tilting to the east.
Scientists tracked the elevation of Venice and its surrounding lagoons over a ten year period and have said that on average, the city is sinking up to two millimetres every year.
It’s thought the subsidence is due to plate tectonics as the Adriatic plate, on which Venice sits, is subducting beneath the Apennines Mountains and causing the city and its environs to drop slightly in elevation.
How often does Venice flood?
Exceptionally high tides in Venice occurs once every four years, on average.
However minor flooding in the city happens around four times a year and usually within the winter months.