A sign in the Lagoon. Photo: Pixabay

Waiting for the tide

A sophisticated submerged dam system has for the first time prevented Venice from flooding. But the future of Venice lies among the fragile habitats of its Lagoon, threatened by man and climate change.
A sophisticated submerged dam system has for the first time prevented Venice from flooding. But the future of Venice lies among the fragile habitats of its Lagoon, threatened by man and climate change.

The waterbus makes its way through calm waters reflecting a vast and bright autumn sky. Just a few people get off the ferry at Ca’ Roman, a small protected strip of land nestled at the entrance of the Venetian Lagoon. Beyond a belt of trees, the horizon opens in a sandy moorland, beyond which, after a deserted beach, lies the Adriatic sea. 

Here, the warm breath of the sea collides with the cool, misty gusts of the Lagoon. As a result, the dunes are covered with moss: a northern European habitat, unique in the Mediterranean. Lipu, the Italian League for the protection of birds, has torn it with difficulty from aspirations of the building contractors.

The images of Venice at the mercy of high tides are periodically, more and more often, travelling around the world, as its destiny runs against the flow of a relentlessly rising sea level. But the lesser-known habitats of the Lagoon, constantly changing because of the currents and human actions, share the uncertain fate of Venice. Unlike the city, places like Ca’ Roman are far from the spotlight. 

When, on October 3, 2020, a system of 78 submerged barriers (MOSE) succeeded for the first time in stopping the high water, the world applauded. MOSE is one of the grandest and most controversial works in Italian history. So far it has cost more than six billion euros, with huge expenses for maintenance yet to come.

Unlike the dams that protect other lower areas in the world, MOSE is hidden in the seabed, it emerges only with exceptional tides.  But despite its invisibility, it attracted an unusual amount of corruption scandals during the thirty-year period from planning to working phase, a time also rife with environmental critiques.  A negative environmental impact assessment, overturned by the regional court amid protests, gives the idea of the level of confrontation. 

Unexpected destruction

The southernmost of the three MOSE’s sectors, closing the inlet of Chioggia, borders Ca’ Roman. To build it, it was necessary to destroy two hectares of reserve.  “But this is the least,” says Luca Mamprin,  forestry doctor who manages the oasis. 

“We had enormous damages, but in a way you wouldn’t expect. During the seventeen years of work, species such as the seagull literally exploded thanks to the food it found on the construction site”. Protected species of birds nested here. Not anymore. “We hid quail eggs in the sand and put camera traps. Well, most eggs were eaten after a few minutes”. 

If the problems at Ca’ Roman can be considered localized effects, they are clues of a much larger phenomenon: the illusion that a single large engineering work is enough to preserve the lagoon. But the acqua alta, or high water, is in fact only one of its threats: pollution, progressive sinking and encroachment of seawater into the aquifers, urban concreting. The mud that makes up the sandbanks and the mudflats hosting the biodiversity of the lagoon is dragged into the sea through deep channels dug for navigation, deepening the lagoon floor. By levelling the seabed, MOSE exacerbates the problem.

The moorlands at Ca’ Roman. Photo: M.Ranocchiari

The MOSE project includes a series of coast protection and environmental restoration works, but specialists often feel like standing in front of a rubber wall, as promises are forgotten and compensation becomes insufficient.

Georg Umgiesser, a German oceanographer naturalized Italian, has developed mathematical models to investigate how often MOSE  will have to be closed with different scenarios of sea-level rise. With a rise of 50 cm, a fairly optimistic forecast according to the IPCC, it would turn from the current 5-10 times a year to over 400. With 75 cm, the Lagoon would be closed for over 6 months per year. This would mean a risk of interrupting the exchange of oxygen with the sea, overwhelming its ecology.

One day, according to Davide Tagliapietra, an ecologist at the National Research Council, the only way to save Venice from the sea level rise might be to have the barriers permanently shut, turning the Lagoon into a coastal lake.

How many times will the Lagoon be closed?

Changing together

There is no doubt that climate change in this unique area poses challenges that, to be won, should first be acknowledged. Yet, despite a huge amount of research and projects on it, there is almost no trace of it in the MOSE promotion materials or in the politician’s speeches. 

The Lagoon and Venice can make it the way they have always done over the centuries: changing together, in a way where it’s hard to tell the natural from the human-made. Even the reserve of Ca’ Roman rose just a century ago for a play of currents following the construction of a pier, and if it stayed almost untouched it is probably thanks to its accidental, recent origin. 

Whichever way, though, complex choices will have to be taken. Is the current policy able to make them? “It is not even able to understand them, let alone decide”, says Tagliapietra harshly. 

At Ca’ Roman, meanwhile, Luca Mamprin explains the frailty of the dunes, heated but patient, to cyclists carelessly whizzing around. And it seems as clear as ever how the fate of small things, sand, canals, sandbanks, is inseparable from that of Venice. 

The Lagoon from Chioggia. Photo: M.Ranocchiari