Venice rose from mudflats in the middle of a lagoon which forms the largest wetland in the Mediterranean. One of the world’s most endangered cities, it has been subject to increasing flooding due to sinking land â€” but also to rising sea levels.
It’s known as "aqua alta" â€” high water â€” and it brings city life to a standstill for several hours. Big boats can’t go under low-hanging bridges, and water seeps into buildings through the sewage system. Venetians have not lived on the ground floor for decades.
Sophisticated technology is now being used for what has become a full-scale emergency. At one of the three inlets that lead from the sea into the lagoon, a massive mechanical hammer is driving a steel and concrete piling into the lagoon bed. Elena Zambardi works for the consortium safeguarding Venice and says the use of pilings was invented by the visionaries who founded the city 1,300 years ago.
"Under the Salute bridge or Rialto Bridge," for example, "there are piles, wooden piles to consolidate the subsoil," she says.
The project acronym is MOSE, which is also the Italian word for Moses, recalling the biblical parting of the sea.
Once completed in 2014, there will be 78 large, mobile flood gates at the three inlets. When not in use, they will sit on the lagoon bed. When a high tide is forecast, Zambardi says, the gates will rise and shut off the sea from the lagoon.
But the project, which is 54 percent completed, has been hounded by controversy and, critics say, may already be outdated.
The IPCC â€” the Intergovernmental Panel on Climate Change â€” has forecast a sea level rise by the end of this century of between 18 and 59 centimeters. But scientists caution it could be even higher.
So a billion dollars for Venice and if the scientific forecasts are correct, this wonâ€™t be enough. How many other cities are going to have start their own battles of the sea. According to the Wall Street Journal, New York is at risk and so are many other cities along the eastern seaboard of Canada and the United States. There are already mobile bulwarks that safeguard London, Rotterdam, and St. Petersburg, While I keep hearing politicians lament the amount of money the Kyoto Accord was going to cost their economies, how much money will it cost to renovate and rebuild the St. Lawrence Seaway or keep Vancouver and Victoria to flood out.
World-wide, cities in 40 countries depend on dikes or seawalls. The seaside of the Netherlands is protected by storm surge barriers big enough to be seen from space. In Venice, Italy, engineers are completing a $7 billion barrier to block high tides that flood the city 100 times a year. In New Orleans, construction crews have started a $700 million barrier to help prevent hurricane floods. In California, it could cost $14 billion to protect 1,100 miles of vulnerable urban coastline with reinforced sea walls and $1.4 billion a year to maintain them and of course the longer we wait, the more expensive the solution will become and that is just for coastal communities. When you factor in the cost on the rest of the country, you realize the cost of inaction is greater than the cost of action.