Patricia Blaci has lived in Venice for 25 years, cherishing the centuries-old floating city for all its beauty and complexity. But after her home was severely damaged by flooding in November, the worst since 1966, she decided to leave.

“It wasn’t an easy decision, I have a deep affection for this city and have fought for it,” Blaci, an architect and tour guide, said. “But it has become too difficult to stay. It’s like living on a boat. Occasionally you get water entering, it rises and then goes down, like a tide. This time it went up a lot higher and lasted for five days.”

Venice’s historical centre and its 11 inhabited islands last year lost 1,092 people to other towns, cities and, in some cases, countries. Blaci, who is relocating to Spain, had been mulling the move for some time, but the deluge gave her the final push.

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Venice, once the heart of a powerful maritime republic, faces many threats to its survival as sea levels rise, but among the most daunting is depopulation. Recurrent flooding, a soaring cost of living, lack of affordable housing and badly managed tourism have driven 120,000 people away since the early 1950s, the majority across the lagoon to the mainland, but over the last 20 years the pace has hastened alongside the advent of cheap flights and flourishing cruise tourism. As many as 60,000 tourists each day in the summer flock to the historic centre where 52,000 people live.

Facebook Twitter Pinterest As many as 60,000 tourists a day visit Venice’s historic centre, many from cruise ships. Photograph: Radosław Kisiel/Alamy Stock Photo

Walk through Venice’s winding alleyways at night, after the day-trippers have gone, and the numerous homes with closed shutters reflect a trend that a succession of administrations have struggled to reverse.

“Look over there,” Blaci said, pointing to a shop selling souvenirs in the San Polo district. “Artisanal shops have closed and have been replaced by these. Money takes precedence. The infrastructure no longer exists for people to live here comfortably.”

Maria Teresa Laghi, who runs one of the few traditional shops left in the area, said: “Venice didn’t lose its soul, it sold it.”

Depopulation dominated a referendum in early December on whether the historic centre and islands should split administratively from the industrial mainland borough of Mestre, with pro-separatists suggesting it could stymie the exodus as it would give them better control over their own affairs.

The referendum, the fifth held since 1979, failed because it did not reach the 50% threshold required for it to be valid. However, it is telling that the majority of those who did vote live in the historic centre and supported autonomy.

“The ‘last survivors’ were in favour of division whereas in the past people mostly voted for union,” said Gilda Zazzara, a history professor at Venice’s Ca’ Foscari University.

The mayor of Venice, Luigi Brugnaro, encouraged citizens to snub the referendum, while his supporters accused campaigners of exploiting fears over depopulation.

Brugnaro’s council argues that the problem is not so much people leaving, as people dying: there were 1,038 deaths across the islands between January and October, and only 361 births. At the same time, while 1,092 people have left, the council registered 1,172 new inhabitants.

Matteo Secchi, who leads the activist group Venessia, disputes the immigration figure. “The number is false, because in so many cases people come here, buy a home, get residency and then rent the home to tourists while living elsewhere. We estimate that around 5,000 ‘inhabitants’ do this.”

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Local authorities are making some attempts to attract young residents, such as spending €7.2m (£6m) on restoring 168 abandoned homes in the historic centre before launching a competition next year for them to be rented out at below-market rate.

However, there are no regulations governing one of the biggest gripes – the landlords who are renting their homes to tourists using sites such as Airbnb, making it impossible for people to rent a home for a reasonable price over the long term.

“This is the main issue,” said Luciana Colle, deputy mayor of Venice. “Private owners are free to do as they wish but maybe they should be more sensitive to the needs of others.”

Those who have resisted leaving say it is their elected leaders who ought to be more sensitive to their needs. They argue that politicians are unable to empathise with the difficulties of life in the lagoon because the majority live on the mainland. Brugnaro, for example, lives more than an hour away and Colle lives in Mestre.

“They like the idea of representing Venice as it is unique in the world and gives prestige,” said Giorgio Suppiej, the president of Venezia Serenissima, a cultural association. “But none of them have got their feet wet or had their homes flooded. We lose around 1,000 people a year and if it carries on this way, it will be the end.”

There are a few bright spots in Venice’s demographics. Over the years, some of the offspring of those who fled have moved back, attracted by the peace (at least in winter), lack of cars, rich history and close-knit community.

“My parents left for Mestre after getting married and had a vision of a brand new home, supermarkets and being able to use a car,” said Martina Cavagnis, who returned to the Canareggio area 20 years ago. “At the beginning people think these things are great, but then they start to miss the lagoon and the community.”