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MOSE: The Amazing Megaproject that Keeps Venice Above Water

Written by Robbie Hadley



            Nearly every culture in the world has their version of a flood myth. In The Bible, God sends a torrential downpour for forty days and forty nights to flood the Earth destroying everything minus a privileged few chosen to survive in Noah’s ark and repopulate the planet. Even older than the biblical tale of the flood is the Epic of Gilgamesh which tells a similar tale of humanity being driven to the brink of extinction due to the rage of an angry god. However, these tales are the stuff of legend no more. With the effects of climate change, humanity faces a flood that could rival the flood of the old testament and coastal cities have already started to prepare for the almost inevitable deluge.

            Despite many of these cities having decades to prepare before the waves reach them, one city already wades in the ever rising waters: Venice. Although the entire city has been designated as a UNESCO World Heritage Site, mother nature has disregarded its protected status and her waters slowly envelop the city. The City of Bridges has fought the waves for over a millenia, and like Caligula who declared war on Neptune himself, the city has fought back against the waves with the Experimental Electromechanical Module, known colloquially as MOSE. Since 2020, this system of movable gates has worked to protect the city from a torrent from the Adriatic sea turning Venice into Atlantis, but with rapidly accelerating climate change, will it even be enough? Even with the project nearly complete, failures in the system and in forecasting could see a project half a century in development all come to naught.  Today we explore one of humanity’s most ambitious fights against the forces of nature itself.

https://upload.wikimedia.org/wikipedia/commons/2/20/Hendrick_Cornelis_Vroom_Het_uitzeilen_van_een_aantal_Oost-Indi%C3%ABvaarders_(1600).jpgThe ‘Mauritius’ and other East Indiamen *oil on canvas *104 × 199 cm *signed c.: Vroom *ca. 1600 – ca. 1630

A Milenia of Mariners

            The Venetians are hardly strangers to the water. Built on a series of islands in the Venetian Lagoon by refugees fleeing invaders from Lombardy in the 7th century C.E., the earliest settlers quickly established it as a trading hub. By the end of the first millenia, you could find trading vessels from such far flung places as Byzantium, the European mainland, North Africa, and even the Arabian peninsula trading in Venice. Acting as a logistic hub for the medieval Mediterranean brought enormous wealth to the small island city state. They even fielded one of the greatest navies of the middle ages, but their success and prosperity would not last. The decline and eventual dissolution of the Byzantine Empire over the next several centuries took a huge toll on the city as they were their largest trading partner. They were eventually folded into other European powers, with control of the island city being passed around until joining Italy in 1866 where it remains today.

Although tourism is its chief industry today, even that revolves around their relationship with the sea. Of the city’s many landmarks, arguably the most famous are its canals and the gondolas that traverse them. The Grand Canal that runs through the center of the city was built around a naturally occurring waterway and the other 176 canals linked the 119 islands. Where other cities have streets, many parts of Venice are accessible only by walking and by boat.

 A rising tide may raise all boats, but it doesn’t lift the ground. Venice first documented flooding within the city in the sixth century, but recent decades have seen the problem significantly exacerbated. Starting around October, the city deals with the Acqua Alta which describes when the flooding in the city reaches over 90cm above normal. Although the most impactful of the floods occurred in 1966 with the mark reaching 194cm above standard, the Acqua Alta occurs over one hundred times a year on average. With the effects of climate change rising sea levels across the globe, Venice sits vulnerable to break these records year after year.

However, the rising sea level isn’t the only flood risk the city faces. The city is sinking. Built on sedimentary sands on Po river delta, the city is constantly settling down into its loose foundation. Despite the fact a casual observer might see it as a sandy, but stable surface to build on, thousands of tons from the weight of the buildings above has caused the city to sink slowly over time. This slow sinking was expedited when the city started pumping water out from the local aquifer which further destabilized the already shaky foundation. They did this for half a century before the danger was noticed and it wasn’t stopped until 1970.


Despite tourism being the chief industry of the city, it is ironically another cause of the city’s ever more difficult battle. Cruise ships dock in the very heart of the city, right next to the iconic St. Mark’s square. This is controversial amongst people in the city. On one hand, these ships bring a massive influx of money to the city as the oceangoing passengers descend upon the city of bridges flush with cash. Others see the enormous ships as a blight on the beautiful city and disrupting the fragile ecosystem along with eroding the canals and waterways that the city sits on. What good is the economic boost if the city disappears underneath the waves? The COVID-19 pandemic gave the city a reprieve with a near total ban on cruises, but with restrictions more or less gone by 2022, the Italian government has banned cruise ships from entering the harbor and is instead paying them to taxi or ferry the tourists in from further away.

Over the last hundred years, the city has sunk nearly 23 centimeters. At the current rate the entire city will be underwater within a century if nothing changes. With the tide moving up and the city sinking down, the problem is obvious. However, the solution was elusive. How do we save the city?

Saving the Sinking City

The MOSE system has been in development for a very long time. In the 1970’s when the city’s severe sinking issue was unearthed, they started to consider different ways the deluge could be held back. By 1980, it was taken over by the Ministry of Public Works and a serious search for a solution was initiated. The idea of making a series of dams, inlets, and dykes seemed to be the best way to save the city from a watery fate. The progress was not fast. It is an enormously complex problem which means the solution would be just as complex.


Despiting handing the city a plethora of challenges, its geography did give Venice one possible solution, the Venetian Lagoon itself. The city of Venice is within an archipelago that extends far beyond the city itself within the Venetian Lagoon. The islands of Lido and Pellestrina almost completely separate the lagoon from the rest of the Adriatic sea. Three narrow inlets allow the water to flow through. If they could control the inlets, they could much more easily control the water level.

Engineers immediately got to work on a solution, but mother nature is not so easily quelled. There were numerous issues to consider. For one, completely blocking off the Venetian lagoon was out of the question. Even without considering the economic impact of cutting off a major port city from the ocean, the environmental impact alone was enough to disqualify damming the entire lagoon off. The lagoon, like coastlines everywhere, is one part of an intricate and delicate system that started developing eons before humans were even in the picture and they were not about to make the problem worse.

            So if damming the inlets was off the table, how could the tide be contained? What if the lagoon could be dammed temporarily, only when flooding was at a particular risk? The idea was almost laughable. Dams have been some of humanity’s largest projects. The idea of a dam that could be put into place as danger approached and then retracted when the threat had passed for the entire lagoon seemed like the scheming of a mad scientist. CNN even compared the facility to the lair of a James Bond villain. It might work on a smaller scale, but how could it possibly dam the ocean? Despite the threat that the entire plan might be unfeasible, it was the only idea that stuck. Nothing else would work, so they got to work on the impossible.


            The eventual solution was ingenious. When not in use, you would not even notice that MOSE is there at all. Cruise ships, fishing boats, schooners, and many more could traverse the narrow inlets between the lagoon and the larger Adriatic sea unimpeded. However, when danger approaches, these guardians emerge from the depths to protect the city. 78 enormous floodgates would remain under the water until needed, but would be filled with air to make them buoyant and rise into place forming three huge ocean walls. Once in place, the sluices would be able to stop the water rushing into the lagoon and therefore into the city.

            It was a bold plan to say the least. After over a decade of planning and groundwork, the design was finalized. Despite hoping to be finished by 1995, work was slow and a projected end date of 2011 as well as a budget of 1.4 billion dollars was settled on. As megaprojects are wont to do, they missed both of these marks by an astounding margin. Numerous difficulties saw the opening delayed to 2014, then 2016, and 2021. The COVID-19 pushed it further back to a projected 2023 completion, but at this point, there are some who wonder if the project will ever be completed. As you might imagine, taking an extra decade or two beyond initial projections ballooned the cost of the project. Although the budget currently sits at over 7 billion dollars, since the project is as of yet incomplete, we can only guess at what the final figure might be.

            On top of the numerous setbacks from design failures, a changing environment, and even erosion from pesky mussels, the project was also plagued by allegations of corruption. In 2014, mayor Giorgio Orsoni of Venice resigned in shame over his connection to an alleged plot to siphon from the project. He and 35 others were arrested in connection to 27 million dollars that is alleged to be traced to corrupt dealings. Some speculate that over 100 people could have profited from the scheme. It was even proposed that Orsoni used the ill gotten gains to buy votes for his reelection for mayor. Orsoni was eventually spared as the statute of limitations ran out, but many still point to his actions as an example of why the project just can’t seem to be completed. Others have also been arrested in connection with similar schemes to defraud the Italian government of these funds and some suspect that the rot uncovered was just the surface and that countless more could be leeching off of the project. However, with no major convictions to date, it just stands as one of MOSE’s many stumbling blocks.


A Lost Cause?

            Currently, the project is in a partially complete state, but is complete enough to be raised into position and start to limit the impact of floods, however its success has been limited. Depressingly, there are many skeptics that don’t believe that MOSE can ever truly achieve its goal. MOSE is designed to stop floods of up to 3 meters and to activate when floods of a certain level are projected. In December 2020, this system failed spectacularly. The forecast drastically underestimated the potential flooding and the system was not brought into operation. By the time they realized the forecast was wrong, it was too late to raise the gates into position and the city was partially underwater once again. We can only begin to imagine the frustration of Venetians, many of whom have spent their entire lives hearing about how MOSE was going to be the city’s salvation, watching the rising tides flow back into the city.


            The one bright spot is that when the barriers are raised in time, they seem to do their job.  If you are wondering why they don’t raise the barriers any time a flood is possible, it costs $300,000 to raise and lower the system a single time due to the energy necessary to pump air and water in and out of the gates. Officials are extremely cautious to only use the system when it is absolutely necessary. On top of the prohibitive cost, raising the barriers is also extremely disruptive to the lives of nearly everyone living on the islands. Everything from trash collection to Amazon deliveries has to be rearranged when no boats can pass in or out of one of the Mediterranean’s busiest ports. Like everything else, they have to decide how much damage is allowable before the cost of the losses outstripps the cost of activating the system and potentially grinding the entire area’s economy to a halt. It isn’t an easy decision to make.

            The last worry is that the system itself may fail from overuse. The longest the barriers have ever continuously operated was for 48 hours and that was just as a test to see how they withstood the abuse. As climate change sends the sea level higher and higher, the necessity for them to operate more frequently and for longer stretches will arise. The Venetians can only hope that the system will hold.

            Even in the absolute best case scenario, the problem isn’t completely mitigated. The amount of flooding needed to see water pooling in St. Mark’s square is far less than is required to kick the system into place, leaving the entire area completely vulnerable. Although there are plans to protect some of the landmarks, many of the businesses and locals who live in the area aren’t so lucky. They simply have to strap on their waders and hope for the best because there is no reprieve in sight for them.


            MOSE is among humanity’s most ambitious projects. Although we have highlighted dozens of projects that have cost more, been more difficult to implement, and affected the lives of many more, MOSE has something that almost none of them have. MOSE is fighting to maintain the status quo despite an ocean desperate to reclaim it as its own. The city has stood for a century and a half blatantly looking down at mother nature and laughing as a Tower of Babel, daring mother nature to reclaim it. She has been supercharged by two centuries of combustion that is raising the tides higher and making waves more ferocious. Mother nature is giving it her damnedest to take the city back and the best we can do is try and hold it off and save one of humanity’s most beautiful landmarks.

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