It was an event that was never meant to happen again.
After suffering centuries of flooding, Venice held back the sea for the first time in 1,200 years in October, thanks to the activation of its long-awaited flood barriers.
Tested for the first time in adverse conditions, their successful deployment kept the historic center dry for the first time in the city’s history. It meant that the devastating floods of 2019 – which caused more than $1 billion worth of damage to the city – should be a thing of the past.
In the two months since its introduction, at the start of what would traditionally be the flooding season, the barrier system, Known as MOSE, has been successfully activated five times – including for a three-day period last week.
But on Tuesday, the barriers were not raised, and the city flooded again.
A ‘terrible situation’
St Mark’s Square, one of the lowest parts of the city, was particularly badly hit, with water thigh deep.
Claudio Vernier, owner of the Al Todaro bar and gelateria, and president of the Associazione Piazza San Marco, told CNN that it was a “dramatic and unexpected event, and one which we thought we had put behind us.”
“We lived through it with great anger,” he said.
“It’s damaging economically and morally, and it could have been avoided. We know the MOSE exists, we know it works, and it was not used.”
The Byzantine Basilica of St Mark, which dates back to the 11th century, suffered “serious damage”, according to Carlo Alberto Tessarin, on the board of the procurators of St Mark’s, who oversee the church.
He told local newspaper Il Gazzettino that they were in a “terrible situation” and that the basilica “cannot take any more of this continual flooding.”
“We’re underwater to a dramatic extent, the damage is serious,” he said.
The church is still recovering from last year’s flood, the salt water from which has eaten away at the marble-clad interiors. Even once the flood has dried up, marble absorbs the salt, which can spread up to seven meters (23 feet), degrading the stone as it goes.
“The basilica is one of the most important works of art in the world, and it is being destroyed,” Vernier told CNN.
Permission to raise the barriers
Until December 2021, the MOSE is officially in a trial phase, and, as such, is under the jurisdiction of the Italian state.
Once finished, the controls will be handed over to the Venetian authorities, but for the next 12 months, every time a high tide is forecast, they must request the barriers be activated by the national government.
The city’s lowest parts, such as St Mark’s Square, are built just under a meter above the average tide level. This means that they start flooding when tides reach just 90 centimeters (35 inches) above the average. The crypt of the basilica floods at just 65 centimeters (25 inches).
Last year’s devastating flood reached 187 centimeters (77 inches) above the average.
When the city authorities take charge, the barriers will be raised when the tide hits 110 centimeters (43 inches) above the average – a level that already sees 12% of the city underwater.
But while it is in its testing phase, it will be activated only when the tide is forecast to break 130 centimeters (51 inches) above the average – by which time almost half of Venice is already under water. By this point, while it may be a centimeter or two in higher parts of the city, St Mark’s Square is already knee deep.
An inaccurate weather forecast
On Tuesday, the tide level hit 138 centimeters (54 inches) above the average – well above the level at which the barriers should be engaged.
But the weather forecast only predicted a tide of 125 centimeters – just two inches below the level at which the barriers are automatically raised. The system was not activated.
As the weather worsened, city authorities sent out alerts to residents warning them to be prepared for flooding. The barriers take several hours to raise, and by the time it was clear how high the tide would be, it was too late to take action.
In the event, half the city was under water, even reaching the raised walkways in St Mark’s Square, which are usually cantilevered over lesser flooding levels.
Vernier is convinced that it was the wrong decision, even at the time.
“Italy is having historically bad and unpredictable weather at the moment,” he said, arguing that the authorities should have taken the precaution of raising the barriers.
“It’s decided on the basis of a weather forecast, and no weather forecast is perfect. Five centimeters (two inches) can make a huge difference, and cause enormous damage – and that’s what we saw yesterday.”