View Full Version : Shielding Venice From the Sea

February 22nd, 2005, 01:36 PM
February 22, 2005

Venice Turns to Future to Rescue Its Past

By ELISABETH ROSENTHAL, International Herald Tribune

Workers repairing the channel of the Squero di San Trovaso, which had been drained.

Jane da Mosto in front of her family's palazzo on the Grand Canal, which has been heavily damaged by high tides.

http://graphics8.nytimes.com/images/dropcap/v.gifENICE - When Jane da Mosto scrambles from the water taxi onto the front steps of her family's ancient palazzo on the Grand Canal, her gaze is tinged with mourning. The once glorious Casa da Mosto is now little more than a decaying, waterlogged shell of a building, the rising and increasingly salty water of Venice lapping at the door and eating away at its walls.

"One day it will just fall into the canal," said Ms. da Mosto, a researcher with Corila, a consortium of groups studying the Venice lagoon in hopes of saving it.

Now, a daring multibillion-dollar construction project sponsored by the Italian government is just getting under way, in an effort to meet that goal. But many, including Ms. da Mosto, are skeptical that it will be enough."I don't like to think about where Venice might be in 100 years," she said. "It's so overwhelming and sad. Maybe it will be closed off as a lake. Maybe it will be underwater and tourists can see it from a glass-bottom boat."

The Venice lagoon is one of the world's most delicate and unstable ecosystems, a unique place where saving a dying natural habitat is crucial to preserving human culture and history: centuries of art and architecture sit within the nature preserve and will be lost if the lagoon succumbs.

And that has prompted increasingly passionate debates here about radical plans now under way to save it - plans that push at the limits of scientific knowledge and engineering capacity.

At the heart of the debate is tension between those who believe in the power of human technology to thwart the forces of nature and those who worry that Italy's master engineers, in their hubris, may only complicate Venice's problem.

The centerpiece of the Italian government's ambitious plan - called the Moses Project, after the parting of the Red Sea - is a series of 78 gargantuan movable underwater dams that would rest on the floor of the Adriatic Sea, massive barriers that would be mechanically raised above the surface when needed to block extraordinary high tide surges. Such tides, which generally now occur a few times a year, produce devastation in Venice that is rapid and, at times, disastrous, like the flood of 1966.

A prime project of Prime Minister Silvio Berlusconi, the high-tech barriers have a political weight that matches their physical heaviness, 300 tons each, and their $4.5 billion price.

"These barriers are a huge environmental intervention on a scale never done before," said Alberto Scotti, the project's chief engineer, who is as confident and pragmatic about the plan as others are emotional.

Critics worry that the huge barriers could further upset nature's delicate balance. They note that the barriers do nothing to allay the city's day-to-day deterioration, a result of more subtle forces in the dying lagoon, requiring less glamorous solutions.

Slowly sinking land and slowly rising water have left many building walls perpetually underwater. Increasing salt content in the canals threatens the city's foundations. The death of plant life on the lagoon bed has turned once variegated channels into conduits for rushing water that pours into the city every time there is a sea squall.

"At the moment, everyone is focused on the barrier - which is very scary because it is a very inflexible and untested solution," said Ms. da Mosto, co-author of "The Science of Saving Venice," a book sponsored by Venice in Peril, a British nongovernmental organization.

"A lot of scientists think it will do the job, and a lot think it won't," she added. "I can't tell you what the solution is, but you also need to stabilize the environment. And what I do know is that the lagoon is immensely complicated, and the more one relies on diverse and reversible solutions the better."

With comprehensive computer models and feasibility studies, Mr. Scotti stands behind his design. "We have checked everything with modeling," he said with a hint of exasperation. "We have models for the morphology of the lagoon. We can reproduce the wind, weather and tides. And our models suggest this will work and will have no negative environmental impact."

Patching up Venice's continuing wounds is already an obsession, and a full-time job, for city officials and residents.

On a recent day in the Squero di San Trovaso, home of Venice's famed gondola workshops, the canals had been drained dry for repairs. Dozens of workers from Insula, a public-private partnership that maintains the canals, are poring over each centimeter of wall, patching up areas of decay and pumping foam through bright green hoses into the walls in order to reinforce them.

"Venice has to be maintained like a boat: you take it out of water and repair it," said Giorgio Barbarini, the driver of a water taxi. "Venice is falling apart because it is hard to maintain a whole city like that."

From an evolutionary standpoint, Venice's decline is perhaps inevitable. Lagoons, with their marshes and brackish waters, are transitional coastal ecosystems, tending to become freshwater lakes or to blend in with the adjacent sea over time. That process accelerates when man cohabits with this unstable bit of nature, as he has here for well over 1,000 years.

Venetians have long manipulated water to protect their city, diverting rivers in the 14th century.

But the rapid changes in the ecosystem have occurred with modernization in the 20th century. Starting in the 1930's, an industrial zone and other lands were created by pumping groundwater out of the marsh, seriously accelerating sinkage. Shipping and pollution that followed eroded many of the crucial defensive features of the lagoon that for centuries helped to keep the sea at bay.

For example, the once textured lagoon floor is now mostly flat and bereft of plants, allowing water surges from sea storms to find their way unimpeded into the city.

The result is that the average water level in Venice is 9 inches, higher than it was a century ago, and perhaps 40 inches higher than 250 years ago, according to researchers at Corila. The once brackish water is now as salty as the sea.

Global warming has not yet contributed substantially to rising water levels here, Ms. da Mosto said. Predictions of the phenomenon's eventual effect on the Adriatic vary widely: some scientists estimate a rise due to global warming of just three inches and others suggest the change may be nearly a yard.

Already, water routinely fills piazzas and seeps into churches. It backs up into homes through the sewers. It corrodes building walls never meant to be submerged. While the foundations of Venetian palazzos were built of materials that withstand water, the walls are brick and porous.

"Lots of money has gone in to replastering and replacing walls brick by brick. We call it the sacrificial layer," Ms. da Mosto said. "But in a few years it is crumbling."

Against this backdrop, designers of the Moses Project often seem perplexed at the resistance in the city they have vowed to save. There were years of negotiations with local officials and environmental groups before construction got under way in May 2003.

Mr. Scotti noted that the project involved not just the barriers, which will be completed by 2010, but also plans to reinforce building walls to protect them from lesser floods, and designs to re-establish wetlands as well. Critics contend that these features are poorly developed afterthoughts.

"People here just accept floods and boots as part of life," Mr. Scotti said. "But living in this condition puts them at a big disadvantage compared to people in Milan and Rome. This will mean a change of life for them."

Mr. Scotti's engineering challenge was enormous, both in terms of the tidal force and the government's requirement that the barriers (far out at sea) be invisible when not in use, a decision that many say unnecessarily added millions to the project.

Teams are now building artificial breakwaters to attenuate tides. Over time, thousands of steel poles will be pounded into the floor of the lagoon. To house the barriers, cement blocks, measuring about 66 yards by 44 yards by 12 yards will be embedded in the sea floor.

It is the very size of the project that terrifies skeptics, who fear that such a huge endeavor will further disturb the lagoon. While the Venice lagoon has been studied extensively by scientists, much of the work was done locally and never coordinated or presented in scientific journals, Ms. da Mosto said. As a result, the complicated ecosystem remains poorly understood, she said.

But designers say they will build slowly and with extraordinary care to create a new safe haven for Venetians - even if it is does not conform with the lagoon's natural form. "Look, there is no natural environment to recover here in Venice anymore," Mr. Scotti said. "It has been changed by man for hundreds of years."

"What is important is to create a lagoon with a lot of possibilities of life," he continued. "The shape will not be natural. The plants will not be the same. There will be artificial material. There are no books on how to build a lagoon.

"We are human, so of course we are not able to reproduce what God made before."


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TLOZ Link5
February 22nd, 2005, 07:16 PM
According to Wikipedia, Venice did not begin to sink rapidly until the 20th century, when artesian wells were dug around the edges of the lagoon to provide water for nearby industry.