(CNN) Venice's misfortunes never seem to stop.

The popular tourist destination has been hit by the worst flooding in 50 years this week, resulting in damage worth hundreds of millions of euros. Italy's Prime Minister Giuseppe Conte said a state of emergency would be declared on Thursday because of the disaster.

The flooding came at the worst possible time for Venice. The city is struggling with unsustainable overtourism , its historical buildings are sinking at an alarming rate and the population is dwindling.

Italian Prime Minister Giuseppe Conte on a boat as he visits the flood-affected city of Venice on November 14, 2019.

Flooding

The lagoon city was struck by an exceptionally high tide on Tuesday night, causing the worst flooding since 1966. Many of its most precious sites have been damaged.

Monsignor Francesco Moraglia, the patriarch of St Mark's Basilica, said he had never seen flooding like this at St. Mark's Square. "There were waves as if we were at the beach," he said.

Mayor Luigi Brugnaro said the damages were "enormous, hundreds of millions of euros."

The Italian government is building a complex flood defense system to protect Venice from flooding. But the multibillion project has been under construction since 2003 and has been delayed a number of times.

In October, the Consorzio Venezia Nuova, the consortium in charge of the project, confirmed another delay, this time because of vibration in some sections of the drain line pipes.

Photos: In photos: High tide floods Venice A city worker helps a woman cross a gangway in Venice, Italy, on Sunday, November 17. Hide Caption 1 of 33 Photos: In photos: High tide floods Venice Pumps spout water from a flooded restaurant on November 17. Hide Caption 2 of 33 Photos: In photos: High tide floods Venice A man sits on a stepladder inside a shop as a woman walks down a flooded street. Hide Caption 3 of 33 Photos: In photos: High tide floods Venice A flooded St. Mark's Square is seen on Friday, November 15, in Venice, Italy. Hide Caption 4 of 33 Photos: In photos: High tide floods Venice People traverse a provisional footpath built over flood waters on Friday, November 15, in Venice, Italy. Hide Caption 5 of 33 Photos: In photos: High tide floods Venice Guests inspect high tidal waters inside a Venice hotel, on Friday, November 15. Hide Caption 6 of 33 Photos: In photos: High tide floods Venice Volunteers treat damaged music sheets from the historical archive of the Conservatorio Benedetto Marcello, on Friday, November 15. Important music sheets have been damaged by unexpected flooding throughout the city of Venice. Hide Caption 7 of 33 Photos: In photos: High tide floods Venice A man carries luggage Friday as he wades through the flood. Hide Caption 8 of 33 Photos: In photos: High tide floods Venice Banksy's migrant child mural is seen partially submerged on Friday. Hide Caption 9 of 33 Photos: In photos: High tide floods Venice A woman checks the state of books from renowned bookstore "Acqua Alta" (High Water) on Friday after flooding in Venice. Hide Caption 10 of 33 Photos: In photos: High tide floods Venice A woman with a selfie stick makes her through a flooded St. Mark's Square. Hide Caption 11 of 33 Photos: In photos: High tide floods Venice People wade Friday through a flooded Venice alley. Hide Caption 12 of 33 Photos: In photos: High tide floods Venice People wearing waterproof shoe covers walk through floodwater on Thursday, November 14, at St. Mark's Square in Venice, Italy. Hide Caption 13 of 33 Photos: In photos: High tide floods Venice In a photo taken on Tuesday, November 12, flooding is seen inside Ferro Fini Palace in Venice. Democratic Party councilor Andrea Zanoni said on Facebook that the Palace's council chamber started to take in water around 10 p.m. local time on Tuesday, as councilors were debating the 2020 regional budget. Hide Caption 14 of 33 Photos: In photos: High tide floods Venice A group of Gondoliers are seen on a pier in Venice, after the city suffered its highest tide in 50 years. Hide Caption 15 of 33 Photos: In photos: High tide floods Venice Italian Prime Minister Giuseppe Conte surveys flood damage in Venice on November 14. Hide Caption 16 of 33 Photos: In photos: High tide floods Venice Members of the municipal police stand in water by St. Mark's Basilica on November 14. Hide Caption 17 of 33 Photos: In photos: High tide floods Venice Head of the Forza Italia party and former Italian Prime Minister Silvio Berlusconi, second from right, assesses the flood damage on November 14. Hide Caption 18 of 33 Photos: In photos: High tide floods Venice A shopkeeper throws out water from his flooded store on Wednesday, November 13. Hide Caption 19 of 33 Photos: In photos: High tide floods Venice A woman sits in a chair in a flooded St. Mark's Square on November 13. Hide Caption 20 of 33 Photos: In photos: High tide floods Venice People walk past a stranded water taxi after it was washed from its mooring by the high tide. Hide Caption 21 of 33 Photos: In photos: High tide floods Venice A woman crosses a flooded St. Mark's Square on November 13, after an exceptionally high tide inundated the area overnight. Hide Caption 22 of 33 Photos: In photos: High tide floods Venice A woman walks her dog through a flooded street on November 13. Hide Caption 23 of 33 Photos: In photos: High tide floods Venice A general view shows a man crossing the flooded St. Mark's Square on November 13. Hide Caption 24 of 33 Photos: In photos: High tide floods Venice Police officers patrol a flooded St. Mark's Square during the high tide on November 12. Hide Caption 25 of 33 Photos: In photos: High tide floods Venice A man stands inside a restaurant barricaded from the flooding on November 12. Hide Caption 26 of 33 Photos: In photos: High tide floods Venice An employee of the Gritti Palace helps a customer navigate a flooded entrance on November 12. Hide Caption 27 of 33 Photos: In photos: High tide floods Venice A woman stands on a barrier during an exceptional "alta acqua" high tide on November 12. Hide Caption 28 of 33 Photos: In photos: High tide floods Venice People traverse a footpath built over the flood waters. Hide Caption 29 of 33 Photos: In photos: High tide floods Venice The entrance to St. Mark's Basilica is flooded on November 12. Hide Caption 30 of 33 Photos: In photos: High tide floods Venice People walk through flood waters in St. Mark's Square on Tuesday. Hide Caption 31 of 33 Photos: In photos: High tide floods Venice The high tide is seen near the Rialto Bridge in Venice. Hide Caption 32 of 33 Photos: In photos: High tide floods Venice A person photographs a flooded St. Mark's Square on November 12. Hide Caption 33 of 33

Climate change

In a tweet, Brugnaro blamed climate change for the unusually high tides, which he described as "a wound that will leave a permanent mark."

While scientists can't definitely blame an individual event on climate change, they say that extreme weather events like flooding or wildfires are happening more often because of climate change.

Venice, already struggling with high tides, is particularly vulnerable to any further rise in the sea levels.

Global sea levels are expected to rise between two to seven feet (0.6 meters to 2.1 meters) -- and possibly more -- over the course of the 21st century. For Venice, this would be a disaster, leaving its streets completely submerged.

A shopkeeper throws out water from his shop during an exceptional high tide on November 13 in Venice.

Sinking city

The flooding risk is made worse by the fact that Venice itself is sinking.

Recent studies using GPS data and radar images determined that various parts of the city and its lagoons are still sinking by between 1 and 4 millimeters (0.04 and 0.16 inches) a year, and the whole city is tilting to the east.

Scientists used to think that much of the sinking was caused by the artificial pumping of ground water from beneath the city, which led to sedimental compression.

However, the new research shows that even though the pumping has stopped, the subsidence hasn't.

Cruise ships & overtourism

Venice is crowded. Really, really crowded. In August, an average 465,100 day-trippers make their way to the city, on top of the 2.2 million tourists who stay overnight, according to National Tourism Agency figures.

Between April to October, an estimated 32,000 cruise ship passengers disembark in the city daily, according to the Port Authority.

Venice authorities have been warning the level of tourism is unsustainable . They floated ideas of introducing an entry charge and banning day trippers and huge cruise liners that cause environmental damage and spoil the views.

Ultimately, Venice announced in August it would start redirecting some cruise ships to neighboring terminals.

People walk across a footbridge on Riva degli Schiavoni on November 14, 2019 in Venice.

Vanishing locals

For many locals, the crowds of tourists simply became too much. Just under 53,000 people call Venice their home, about one third of the level it was 50 years ago.

The population is aging, with youngsters leaving to look for work outside the tourism sector.

That is a bad news for the local economy and its future population projections.