Articles
May 28, 2003
In the Fray: Venice Preserved? Giant Sea Gates May Be Swamped By John Keahey
© 2003, The Wall Street Journal
Venice and the Italian government, it appears, are going forward with the long awaited, and much debated, mobile-gates project that supporters believe will save the city from the rising waters of the Adriatic Sea. The gates are called Mose -- the Italian name (pronounced Mow-zay) for Moses, the biblical prophet who ordered the Red Sea's waters to ebb and flow.
Earlier this month, with protesters noisily ensconced in boats along the city's famous canals, Italian Prime Minister Silvio Berlusconi symbolically "blessed" the first stones destined for Mose's foundations. These stones will be buried along the bottoms of the three entrances to the lagoon surrounding Venice.
The massive project is expected to cost $3 billion to $4 billion. Its centerpiece is a series of 79 steel flaps. They would rise on command when an Adriatic Sea tide is expected to bring water into the lagoon that is at least 44 inches above the level at which the city's lowest areas would begin to flood. The theory is that while Venice would experience some minor flooding each year, the gates would hold back the more damaging floods. Supporters believe the gates would be up, on average, only five times a year. Once the threat of acqua alta, or high water, passes, these flaps would be lowered back into their hidden nests.
The worst flooding usually comes when a major storm system occurs at high tide. A storm-generated low-pressure system pulls water up into a huge "dome." Winds then push this dome up the Adriatic on top of the high tide.
The great irony of Venice is that the sea, which protected the maritime republic from all invaders for a millennium, now threatens to destroy her. The Adriatic's relative sea level increased 9.2 inches during the 20th century -- caused by a combination of land sinking and seas rising because of a variety of climatic shifts. Sea levels rise and fall in cycles, and scientists disagree how long this current "up" cycle will last.
Sea-level increases in the city are nothing new. Venetians dealt with them over the centuries by demolishing older buildings built on lower foundations. They would raise the foundations and create new structures. But today this practice is unthinkable in the preserved, living museum that Venice has become. Floods that once invaded lower areas only seven times in 1900 now creep in nearly 100 times a year. Lifelong residents are escaping to the mainland, gradually turning their city over to the 12 million to 15 million tourists who visit annually.
Those who stay are philosophical. Knowing that their ancestors readily adapted to fluctuations in their aquatic environment, they often say, "The water goes up. It goes down. What's the problem?"
But opponents of Mose believe that by the time the gates are completed -- probably more than a decade from now if funding stays on track -- Mose's operators will be raising the gates more often than five times a year, trapping waste and pollutants in the lagoon for longer periods than normal. Remember: Venice has no traditional sewer system; waste flows from homes and businesses into the city's canals, where it waits for the twice daily, cleansing tides.
And while supporters are betting that the gates will work, even if the sea level rises as much as 24 inches over the next century, many climatologists fear the rise will be much greater -- perhaps as much as 32 inches or more. This, they believe, could render Mose ineffective in as few as 50 years.
If this happens, Mose offers no foundation upon which to build a longer-term solution. The mobile gates would have to be removed and an entirely different safeguard developed to preserve the historic center for future generations.
Mose opponents have filed lawsuits challenging the project, calling for more detailed environmental studies of the lagoon's ecosystem and of the impact the gates project would have on it. These opponents are made up of a small group of climatologists, archaeologists, geologists, hydrologists, and some members of the Venice City Council, as well as Italy's leading environmental organization, Italia Nostra (Our Italy). They want to reopen the competition for a longer-term solution to acqua alta.
This would be the proper course. A consortium of construction companies -- Consorzio Venezia Nuova, created 20 years ago -- has, in the face of heavy criticism, never seriously considered any option but the mobile gates.
Perhaps it is time to evaluate a "Dutch solution" -- building a huge dike around the historic center and creating a Venetian "lake" where the water inflow and outflow can effectively be controlled. But whatever the final choice, Venice must be protected from the sea that once was its protector and is now rapidly becoming its conqueror.
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Mr. Keahey, a Utah-based journalist, is the author of "Venice Against the Sea: A City Besieged" (Thomas Dunne Books/St. Martin's Press, 2002).
© 2011 John Keahey