Venice was braced on Sunday for an unprecedented third major flooding in less than a week, with seawater due to swamp the already devastated historic city where authorities have declared a state of emergency.
The city forecast "acqua alta," or high water, of 160 centimeters for 1200 GMT, lower than Tuesday's 187 centimeters – the highest level in half a century – but still dangerous.
"Maximum attention for today's tide," tweeted mayor Luigi Brugnaro, who has estimated damage so far from the invading saltwater at over 1 billion euros ($1.10 billion).
"The safety apparatus has been activated. Thanks to all those who are looking after Venice and intervene when needed."
The renewed threat from exceptionally intense high tides came after a brief respite Saturday, with visitors on Sunday morning having to walk along improvised gangways on St Mark's Square as the waters rose yet again.
The top tourist site had been shut for several hours Friday as strong storms and winds battered the region, leaving it submerged by sea surges.
Churches, shops and homes have also been inundated in the city, a UNESCO World Heritage site.
Members of the Italian football team traveled to Venice on Saturday to show solidarity with the stricken city.
"Venice will overcome this too. Like an athlete who suffers a serious injury and then gets up again," said delegation chief and former Azzurri international Gianluca Vialli.
The crisis has prompted the government to release 20 million euros in funds to tackle the devastation.
Culture Minister Dario Franceschini has warned the task of repairing the city, where more than 50 churches have suffered damage, will be huge.
Hotel reservations canceled
Residents whose houses have been hit are eligible for up to 5,000 euros in immediate government aid, while restaurant and shop owners can receive up to 20,000 euros and apply for later.
Most of the city's cash machines were no longer working because of the water, making life even more difficult for tourists and Venetians.
Older residents who remember the infamous "acqua alta" of 1966, when the water rose to a level of 1.94 meters, say they have not seen such frequent flooding before.
Hotels reported canceled reservations, some as far ahead as December, following the widespread diffusion of images of Venice underwater.
Tuesday's high waters submerged around 80% of the city, officials said.
Many, including Venice's mayor, have blamed the disaster on global warming and warned that the country prone to natural disasters must wake up to the risks posed by ever more volatile seasons.
Mayor Brugnaro on Saturday said he had invited the U.N. to set up a climate change research center in Venice.
"We want to launch a great global appeal to scientists: come here, you will find open doors and a city ready to welcome you," Brugnaro said.
The Serenissima, as the floating city is called, is home to 50,000 residents but receives 36 million visitors each year.
A massive infrastructure project called MOSE has been underway since 2003 to protect the city, but it has been plagued by cost overruns, corruption scandals and delays.