Inside Venice’s bid to hold back the tide – article on the city’s MOSE dams in The Guardian
This article by journalist Antonia Windsor was published by The Guardian (UK) in its resilient cities series on 16 June 2015. The article is a perceptive insight into the discussion about Venice sinking and especially protecting the city with the MOSE flood barriers, which are nearing completion. There are numerous quotes from key figures involved in debates about this project and I declare an interest that I have also offered some remarks. This is a link to the website addition which includes some useful photographs and follow-up comments on the article (the text is also copied below);
Inside Venice’s bid to hold back the tide
With the city slipping slowly into the lagoon and sea levels continuing to rise, the delayed €5.4bn Mose flood barrier project will be fighting the laws of nature
Tuesday 16 June 2015
Later this summer the final stages of Venice’s Mose flood barrier project will begin completion as the gates arrive and are inserted into their concrete foundations on the bed of the Venetian lagoon. The gates, which will be situated in the three inlets through which water enters and leaves the lagoon, will be able to be opened and closed separately to control the flow of water and help to control the high tides, or acqua alta, that mire Venice every winter.
The working of the gates will be quite similar to London’s Thames Barrier, thanks to the knowledge and experience shared within the flood-defence club, I-Storm (International Network for Storm Surge Barrier Managers), of which London and Venice are both members.
In the Mose control centre in a converted chapel in Venice’s Arsenal, nine people are looking at various hi-tech screens with graphs, charts and diagrams monitoring the conditions of the lagoon. For nearly five years they have been opening and closing imaginary gates, simulating the flood defence in real-time. “The gates will start operating as soon as they are fitted,” says Roberto Chiarlo, manager of Thetis, the monitoring network and environmental measurements department. “It is the easiest part of the work that is left.”
The hard part – building the 23,000 tonne concrete foundations and lowering them into the lagoon – has already been completed. The delivery of the gates will include a spare for each of the three inlets, enabling them to be removed and maintained every five years without interrupting the service of the barrier. Each hinge on the gates will have a waterproof camera permitting them to be accurately controlled.
The centre has been simulating the control of the gates since 2011, collecting data that enables the creation of mathematical and statistical models that can be entered into the decision support system. “We have full control in real time,” says Chiarlo “We know which angle to raise the gate to make it most efficient. We can predict the tidal movement for the next five days and see if flooding is predicted.”
The factors being considered are wind, water level, waves, pressure and fresh flood from the rivers. The barriers will be able to support a three-metre-high tide and will protect Venice for a century. “The commercial harbour will be impacted each time the barriers are lifted and there would be thousands of dollars of electricity used,” says Chiarlo. “We need to protect Venice but we also have economic activities in Venice and there will be a conflict between the two – there will need to be negotiation on each decision.”
Since the Mose model was first proposed in 1988, it has faced a barrage of criticism from environmental campaigners who believe that it will alter the biodiversity of the lagoon – but Chiarlo rejects their claims. “We have made an impact assessment and as the gates will only be raised for a couple of hours; the impact is minimal,” he says.
In another camp, many are positive about the barrier’s potential impact on the natural environment of the lagoon’s islands, which is subject to severe damage during the flooding season. “The historic flood of November 4 1966, which saw water reach 194cm, signalled the end of lagoon agriculture and was responsible for the death of the majority of lagoon plant life,” says Matteo Bisol, manager of the vineyard Venissa on the island of Mazzorbo. “There was a lot of winemaking in the lagoon in the 19th century but it had all but vanished when we decided to resurrect it in 2002 in a walled vineyard that had contained vines since 1300. In the past few years, acqua alta has reached Venissa, but the vines have always survived. The Mose barrier will hopefully mean they will be protected in the future.”
Furthermore, a recent cost-benefit analysis shows that the barriers will more than pay for themselves in 50 years through the reduction of maintenance and repair costs caused by the annual floods.
Acqua alta occurs regularly during the winter months . “For anyone who is not Venetian, it is always amazing to see how residents in the city take the phenomenon of the high tides and exceptional water levels in their stride,” says Paolo Canestrelli, director of the city’s tide monitoring and forecast centre. “We have a series of flexible measures in place that limit the extent of the problem. Sirens sound a warning throughout the city when a high tide is forecast; information is provided in real time via the web and mobile telephones; temporary elevated platforms are set up in the parts of the city with heavier pedestrian traffic, while some public water transport lines are diverted to all-weather routes.”
“We have to consider that high tides last an average of two hours and 30 min and citizens, commerce and transport are warned in time to plan alternative routes, to put all goods away safely and to wear boots. They know that in two hours the tide will flow back to the sea. Venice has always shown its ability to adapt.”
Dominic Standish, academic and author of Venice in Environmental Peril? Myth and Reality, agrees that Venetians have always adapted to the unique problems of living in the lagoon. “Mose is continuing in the tradition of the Venetian Republic, which intervened in the lagoon to protect against natural threats. Ancient Venetians built sea walls and diverted two major rivers – these were huge engineering projects,” he explains. “The Venetian Republic suffered more from flooding than we do now. People were regularly killed by flooding. They had difficulty in predicting it. Venice is much better protected now than it has been for a long time.”
Jonathan Keates is chairman of the UK-based Venice In Peril Fund, which has received £2m from sales of the Pizza Express Veneziana pizza since 1977 for restoration and conservation work in the city. He agrees that Venice is in a strong position at the moment: “The city, in terms of built environment, is in better shape than it has ever been. Regular dredging of canals has lessened the impact of rising water levels, and the Mose barriers – whatever the doomsters predict – are likely to be a major factor in halting inundation for a long time, and the sinking of the city has abated since the construction of aqueducts obviating the need to draw water from the subsoil.”
Venice is a cluster of 124 island settlements that began in the 7th century and gradually coalesced into the city we know today. Venetians have always had to conquer land from the lagoon and defend it from the sea. The beautiful faded palazzos, whose facades are the pretty face of the city, are a feat of medieval engineering. Built on wooden stilts and without fixed masonry, the buildings were designed to move and adapt to the uneven settling of the ground beneath. “The natural course for a lagoon is to either become dry land or to disappear back into the sea,” explains Standish. “To preserve Venice has always been to interfere in the natural course of events.”
Since last summer, the work on the flood barriers has slowed, thanks to an ongoing investigation into the corruption surrounding the Mose project. Allegations of bribery and illegal financing of political parties resulted in 35 arrests last June. Among those arrested was Giovanni Mazzacurati, the then president of Consorzio Venezia Nuova, the consortium responsible for the project and charged with safeguarding the lagoon. Mazzacurati was accused of diverting funds to mayor Giorgio Orsoni to finance his 2010 campaign for office. The alleged web of bribes and kickbacks involved several politicians, according to investigators. Orsoni was also arrested, along with the former governor of the Veneto Giancarlo Galan who was briefly imprisoned in Milan before being granted house arrest at his villa in Padua, northern Italy.
“After the arrests of 4 June 2014 there have been setbacks,” says Luigi Magistro, the new commissioner of Mose appointed by the national anti-corruption authority last month. “The checks and controls have been increased. There has been a slowdown, and now the time schedule will slip back a few months. But it is the price to pay for legality.”
The flood barrier was due to be up and running as early as next year, but some detractors now say work might not be completed until 2018 or even 2020. However, at a cost of €5.4bn (£3.9bn) to the Italian government, there is no going back. The project will be completed.
“I am confident that once we start there will be no arguments,” says Mose’s general manager, Hermes Redi. “Once the gates are in operation there will be a much better management of the lagoon.”
Redi says Venice has “sunk” 23cm in the last century as a result of sea level rises and subsidence, largely due to the extraction of groundwater, which stopped in the 1970s. “We haven’t had a problem with Venice sinking for the past 50 years. Now our problem is the sea-level rising”, he says. “With these barriers we will be the only city in the world which will be protected if the sea-level rises up to 1 metre – if water goes up more than 1m it is not Venice that is in peril, it is Italy.”
However, not everyone agrees that Venice has stopped sinking. In 2012 a study by Scripps Institution of Oceanography in San Diego found that Venice had not stabilised as previously thought, but was continuing to slowly sink – and to tilt eastward. “Venice appears to be continuing to subside at a rate of about 2mm a year,” says Yehuda Bock, a research geodesist with Scripps who has been studying Venice subsidence since 2001. “It’s a small effect, but it’s important.” he added. The sea level is rising in the Venetian lagoon at a rate of 2mm per year, so this slight subsidence doubles the rate at which the heights of surrounding waters are increasing relative to the elevation of the city, he observed in the study. In the next 20 years, if Venice and its immediate surroundings subsided at the current rate, researchers would expect the land to sink up to 80mm relative to the sea.
The idea of Venice sinking has long captured the imagination and has featured in countless artistic works, including theatre director Robert Lepage’s 1990 production of Tectonic Plates, during which he famously flooded the stage of the National Theatre to stage an art auction in which punters were bidding on famous paintings while wading knee deep in water.
“Venice as a metaphor for death and human frailty dates back to the early 19th century. ‘In the fall of Venice think of thine,’ wrote poet Lord Byron in 1812,” says Standish. “The fall of the Venetian Republic in 1797 created a predisposition to embrace any sign of Venice’s downfall. John Ruskin’s 1860 book provided details of the city’s stones for the generations he feared would never see it. When the bell tower in St Mark’s Square collapsed in 1902, it was taken as a sign that Venice was sinking … In the 20th century, Thomas Mann’s Death in Venice consolidated the association of the city with mortality.”
“The idea that St Mark’s Basilica will one day become a species of Debussian cathedrale engloutie, with coral-encrusted statues and fish swimming across the mosaics and the Pala d’Oro turned into an oyster-bed, is no doubt an alluring one for some,” says Keates. “Frankly I don’t share it. Neither am I, or my fellow trustees, in favour of the ‘Let it fall down’ school of thought, which is simply an excuse for idleness, apathy and philistinism. If the thought of Venice sinking captures the imagination, then it should be as a wakeup call to save the city as an essential basis of the civilization we cherish. The world owes huge debts to Venice, including modern systems of democratic government and the printed book.”
Back at the Mose control centre Chiarlo says he hopes his team will grow in the next few years so the centre can be manned 24 hours a day. “We are doing an important job,” he says. “We are saving Venice.”
For another blog post on the MOSE dams click on this link: