Criminal
01-13-2005, 05:34 AM
http://www.sciam.com/article.cfm?articleID=00088E1F-D709-1D5B-90FB809EC5880000
It is 6 a.m. on New Year’s Day, 2001, in the picturesque city of Venice, Italy. Sirens blare across the piazza, warning of impending high tides. Venetians wake once again to the war against the waters. It’s a war they are currently losing. Venice is sinking, and could be submerged by the end of the century.
Now Project Moses, a controversial $3-billion-dollar government-funded scheme to keep Venice above water, has finally been given the go-ahead by Italian officials. Construction of its novel floodgates is set to begin in December 2002, following years of false starts. But some scientists still object to the project, saying that it will damage local ecosystems and is doomed to obsolescence within years if the sea level rises as predicted by current climate-change models. Moses may yet have a few mountains to climb before parting Venice from the sea.
The Tide Turns
To better understand why Venice is so troubled, it helps to consider its history. Venice is a city on stilts. Built on 117 small islands in the middle of a lagoon that flows into the Adriatic Sea, the city has origins that stretch back to Attila the Hun’s invasion of Italy in 452. People sought refuge on the lagoon’s islands, and the tidal channels have guarded settlers for centuries since. In 810, Venice’s watery ramparts blocked the forces of Pepin, a son of Charlemagne, who had rampaged through Italy, seizing land-based towns.
However, the waters that have defended Venice are now its greatest threat. In 1966, a meter of water blanketed the city, prompting the Italian government to label safeguarding Venice as a matter of "priority national interest." In the years that followed, the Consorzio Venezia Nuova (CVN), the private consortium of engineers and architects behind the floodgate project, was founded and charged with the task of keeping Venice from drowning.
Water, Water Everywhere
Venice is sinking about half an inch per century. Italy, as part of the African geological plate is drifting north, pushing under the European plate. This is causing the Alps to rise and Venice to sink. The subsidence was exacerbated by industries pumping groundwater from below the city, for manufacturing and agricultural purposes, after World War II. That practice--which was stopped in the 1970s--caused the city to sink a foot in two decades. As a result, the world-famous St. Mark’s Square, the center of Venetian social life, stands just two inches above the normal high-tide level. The square stands under four inches of water in flood events that occur around 100 times a year. And things are getting worse. January 2001 saw the worst spate of sustained flooding in the city’s history, which lasted more than a fortnight, with an eighth of the city underwater. Add to that the projected sea-level rises due to global warming, and the peril of a city sinking without a trace becomes depressingly clear.
Parting the Sea
Since 1951, 90,000 people have left Venice, and the 60,000 who remain live in fear of a repeat of the 1966 floods. The CVN’s solution is the Mo.S.E. (Modulo Sperimentale Elettromeccanico, or Experimental Electromechanical Module) Project. It involves the construction of a set of 79 mobile floodgates that will separate the lagoon from the Adriatic when the tide exceeds one meter above the usual high-water mark. Similar gates have been constructed in London and Rotterdam, but they are large aesthetic intrusions on the landscape. The Italian government is adamant that the construction project should not have an impact on Venice’s scenery. During normal tides, the 300-ton mobile gates are designed to lie flat on the seabed, inactive and filled with water, hidden from view. When a tide of one meter is forecast, air will be injected into the gates, pushing out the water and causing the gates to rise. As the tide drops, the gates will be refilled with water and return to rest on the seabed.
The mobile gates were first proposed more than a decade ago, so why has it taken so long for approval? The answer is that Project Moses has had to overcome many environmental objections. Italy’s Green Party fears that closing the lagoon for long periods will cause it to stagnate, damaging marine life. To appease the Greens, the CVN has implemented many complementary projects to defend the city by alternative methods, often repairing damage caused by earlier makeshift attempts to stem the tides (see sidebar).
It is 6 a.m. on New Year’s Day, 2001, in the picturesque city of Venice, Italy. Sirens blare across the piazza, warning of impending high tides. Venetians wake once again to the war against the waters. It’s a war they are currently losing. Venice is sinking, and could be submerged by the end of the century.
Now Project Moses, a controversial $3-billion-dollar government-funded scheme to keep Venice above water, has finally been given the go-ahead by Italian officials. Construction of its novel floodgates is set to begin in December 2002, following years of false starts. But some scientists still object to the project, saying that it will damage local ecosystems and is doomed to obsolescence within years if the sea level rises as predicted by current climate-change models. Moses may yet have a few mountains to climb before parting Venice from the sea.
The Tide Turns
To better understand why Venice is so troubled, it helps to consider its history. Venice is a city on stilts. Built on 117 small islands in the middle of a lagoon that flows into the Adriatic Sea, the city has origins that stretch back to Attila the Hun’s invasion of Italy in 452. People sought refuge on the lagoon’s islands, and the tidal channels have guarded settlers for centuries since. In 810, Venice’s watery ramparts blocked the forces of Pepin, a son of Charlemagne, who had rampaged through Italy, seizing land-based towns.
However, the waters that have defended Venice are now its greatest threat. In 1966, a meter of water blanketed the city, prompting the Italian government to label safeguarding Venice as a matter of "priority national interest." In the years that followed, the Consorzio Venezia Nuova (CVN), the private consortium of engineers and architects behind the floodgate project, was founded and charged with the task of keeping Venice from drowning.
Water, Water Everywhere
Venice is sinking about half an inch per century. Italy, as part of the African geological plate is drifting north, pushing under the European plate. This is causing the Alps to rise and Venice to sink. The subsidence was exacerbated by industries pumping groundwater from below the city, for manufacturing and agricultural purposes, after World War II. That practice--which was stopped in the 1970s--caused the city to sink a foot in two decades. As a result, the world-famous St. Mark’s Square, the center of Venetian social life, stands just two inches above the normal high-tide level. The square stands under four inches of water in flood events that occur around 100 times a year. And things are getting worse. January 2001 saw the worst spate of sustained flooding in the city’s history, which lasted more than a fortnight, with an eighth of the city underwater. Add to that the projected sea-level rises due to global warming, and the peril of a city sinking without a trace becomes depressingly clear.
Parting the Sea
Since 1951, 90,000 people have left Venice, and the 60,000 who remain live in fear of a repeat of the 1966 floods. The CVN’s solution is the Mo.S.E. (Modulo Sperimentale Elettromeccanico, or Experimental Electromechanical Module) Project. It involves the construction of a set of 79 mobile floodgates that will separate the lagoon from the Adriatic when the tide exceeds one meter above the usual high-water mark. Similar gates have been constructed in London and Rotterdam, but they are large aesthetic intrusions on the landscape. The Italian government is adamant that the construction project should not have an impact on Venice’s scenery. During normal tides, the 300-ton mobile gates are designed to lie flat on the seabed, inactive and filled with water, hidden from view. When a tide of one meter is forecast, air will be injected into the gates, pushing out the water and causing the gates to rise. As the tide drops, the gates will be refilled with water and return to rest on the seabed.
The mobile gates were first proposed more than a decade ago, so why has it taken so long for approval? The answer is that Project Moses has had to overcome many environmental objections. Italy’s Green Party fears that closing the lagoon for long periods will cause it to stagnate, damaging marine life. To appease the Greens, the CVN has implemented many complementary projects to defend the city by alternative methods, often repairing damage caused by earlier makeshift attempts to stem the tides (see sidebar).