I was touched by the amazing floods in Venice last week. My wife (descended from Decollatura, Catanzaro, Calabria) said that the images of Venice in flood were like nothing she has ever seen in her lifetime.
The simple numbers are stunning - even for a city that floods regularly; driven by strong winds from the Adriatic, the acqua alta in the lagoon surrounding the city rose 156cm (61in) above normal levels - the deepest flood in 22 years, and the fourth highest flood level since 1872.

My instinctive reaction was to jump to the conclusion that Venice is sinking. After all, these are potent images and are constantly brought up each time the acqua alta makes its mark.
But then on reflection, I started to think that there is a difference between ‘flooding’ and ’sinking’, with last week’s flood being taken as proof that Venice is in fact sinking. I’m not sure that the two scenarios are so closely inter-connected.

Veniceforvisitors.com says that:

Although the city did sink about 10 cm in the 20th Century because of industrial groundwater extraction, the sinking largely stopped when artesian wells on the mainland were capped in the 1960s.
Today, subsidence is estimated at 0.5 to 1 mm per year, mostly due to geological factors and compression of the land beneath the city’s millions of wooden pilings.
A larger problem is the rising sea level, which will become an even bigger threat as global warming melts the arctic ice caps. Already, the frequency of acqua alta has increased from fewer than 10 times a year to more than 60 times a year in the last century.

Acqua alta typically occurs when a set of natural circumstances align:

1. A very high tide (usually during a full or new moon)
2. Low atmospheric pressure
3. A scirocco wind blowing up the narrow, shallow Adriatic Sea, which forces water into the Venetian Lagoon

A couple of other interesting points:

• The phenomenon is most likely to take place between late September and April, and especially in the months of October, November, and December
• By official definition, acqua alta occurs when the tide is 90 mm (3.54 inches) above normal high tide
• The actual depth of water in the streets is far less than the “level of tide” might suggest. (the 2004 flood is a case in point - 135 cm of flooding translated into 40 cm of water in the Piazza San Marco)

That made me think about efforts to preserve this most precious of cities.
It seems to me that any effort to provide a permanent solution would be remarkably expensive, particularly given the city’s relatively small population of 271,000. And it’s fair to say that in the best Italian tradition, it doesn’t take much effort to uncover an ages-old debate that is passionate, opinionated and guaranteed to raise tempers!

The MOSE Project is designed to protect Venice but has a long and chequered history.
Wikipedia summarises MOSE as

…an integrated defence system consisting of rows of mobile gates able to isolate the Venetian Lagoon from the Adriatic Sea when the tide reaches above an established level (110 cm) and up to a maximum of 3 m. Together with other complementary measures such as coastal reinforcement, the raising of quaysides and paving and improvement of the lagoon environment, these barriers will protect the city of Venice from extreme events such as the floods and from morphological degradation. Work on the project has been underway since 2003 at the three lagoon inlets of Lido, Malamocco and Chioggia, the gaps connecting the lagoon with the sea and through which the tide ebbs and flows.

The project is expected to cost €4,272 million, against a budget of €3,000 million. To March 2008, approximately 40% of the work has been completed at a cost of €2,440 million. On 31 January 2008, the fifth tranche of €400 million was released and construction of the caissons, the most important and final part of the project, could begin. 

MOSES is due for completion between 2012 and 2014. But there is still no single body responsible for the defence of the city, and no plan for its long-term preservation, let alone funding.

There has long been resistance to MOSE from environmental and conservationist groups, largely on the the basis of the excessive cost, monolithic nature of the MOSE solution (and its ineffectiveness against rising sea levels) and wide ranging changes being made to the sea bed. In the best Italian tradition, political arguments between pro and anti forces have raged down the years, with Greens, Communists and Socialists siding in the ’80s to oppose the project on the basis that it is ecologically unsound and favors big business.

During the years, nine appeals have also been presented. Eight have been rejected on various grounds with the 9th currently being examined.

Crucially, the barrier scheme’s opponents include Venice’s mayor, Massimo Cacciari, who is struggling to run the city on a budget reduced to fund Moses.

Sounds like the arguments are going to continue for a while yet.