Venetians' dilemma: To save the lagoon or the city?

2024-01-24 09:04:00, Kulturë CNA

The World Climate Council predicts that by the end of this century, the city's water level will rise by 60 centimeters. Even though Venice's flood protection system has been working for years, the lagoon continues to be at risk.

For more than 1600 years, Venice has amazed the world. So early is the fear that the city could be flooded and could disappear under water. The latest attempt to protect the city from excess water concerns the construction of an underwater system of 78 iron walls separating the lagoon from the sea, a system called MOSE.

Elisabetta Spitz, Architect and Commissioner for the Protection of Venice from Floods:

"Had it not been for MOSES, Venice would have been irreparably destroyed on November 22, 2022. That day we had the second biggest flood in the history of the city, but there were no consequences and we managed to protect the lagoon and Venice."

Elisabetta Spitz gave the order to raise the water gates 52 times. MOSE is being used more and more. Now the system is fully operational.

Elisabetta Spitz: "Now we know that MOSE is a flexible instrument that does not always close at the same time. Today we know a lot more about flood waves and winds, so we are able to fight floods, we are able to use MOSE even partially, thus guaranteeing the passage of water between the sea and the lagoon.

Venetians' dilemma: To save the lagoon or the city?

So is Venice protected in this way? The World Climate Council predicts that by the end of this century, the city's water level will rise by 60 centimeters. Through the MOSE system Venice has only gained time, says oceanographer Georg Umgiesser.

“Is MOSE enough to save Venice? Yes, right now and in the next ten, twenty and thirty years, for sure. But if the water level rises by 50 centimeters, then the system must be used 300 to 400 times per week, which means once a day. But the system thus exceeds its capacities. It is no longer able to function. MOSE is no longer able to function, but neither is the lagoon, because the lagoon needs water circulation."

Marco Sigovini also works at the Institute for the study of waters, which deals with the study of the ecological system of the lagoon. The frequency with which MOSE is now being used has no major consequences, says the biologist. But this thing will change, when after a few years the lagoon is separated from the sea more and more often and for a longer time.

"It may happen that one day we have to make a decision if it makes sense to continue to keep the lagoon as a saltwater lagoon. With the long-term closing of the gates, the circulation of waters between the lagoon and the sea, which is fundamental to Venice, will be interrupted. Through this circulation, the base of the lagoon is formed and the types of plants and animals that live there depend on it. We will be facing difficult decisions."

And one must have courage. It is often forgotten, says Umgiesser, that in the last 150 years the level of Venice has dropped 30 centimeters. The reason: a lot of water has been pumped from the base of the underground water from the foundation of the city. But the basic groundwater level could help save the city from collapse.

"If the water that has been pumped out of the underground water, returns to where it was then the level of Venice would rise again by 30 cm. And this increase in level meant that in this way we would gain 30 cm that we have lost in the last 150 years, so as to say we would go back to level zero."

But Venice will not live forever as we know it, says the water researcher. Someday the day will come when the sea is separated from the lagoon.

A difficult decision. The Venetians hope to delay the decision as much as possible.

To save the lagoon or to save the city? The Venetians would like to save both./ DW