High water, or acqua alta, is a persistent phenomenon throughout theVenetian lagoon. Over the centuries, the city's leaders, merchants, andresidents have dealt with rising sea levels either by demolishing old buildingsand erecting new ones on higher, impermeable-stone foundations, or by raisingthe entrances to buildings that line the dozens of canals criss-crossing thehistoric city. Or, on the then-rare occasions when the city was flooded bystorm-driven tides, Venetians simply waited it out. The water went up, a fewhours later it went down, and life, scarcely disturbed, went on.
As Venice evolved from a mercantile republic into a living museum, city fatherspreserved historic buildings rather than razing them to make way for newstructures. It simply would not do to create a modern city atop the ruins ofthe old, as has been done throughout the world. Such a Venice would not be theVenice the world has come to cherish.
A city awash
The 20th century, with its rampant industrialization and its witnessing ofclimate shifts, changed all that (see Venice Under Siege). Many scientistsbelieve that global warming driven by the burning of fossil fuels is primarilyresponsible for the rise in global sea level, which at Venice has resulted inhigher and more frequent instances of acqua alta. To make matters worse, Venicehas been sinking over the centuries, due to the natural settling of lagoonsediments and the indiscriminate pumping of freshwater from a deep aquiferbeneath the city.
Sixteen hundred years ago, around the time of Venice's founding, the Adriatic'sstandard sea level was almost six feet below what it is today. For a millennium and ahalf, Venetians were able to cope with the problems associated with living in awater-dominated environment. As late as 1900, for example, water at extremehigh tide covered St. Mark's Square only seven times a year.
Boats cannot navigate the canals during the highest tides becausethey cannot pass under bridges.
By 1989, however, such inundation occurred no fewer than 40 times a year. In1996, water nearly as high as the average tourist's knee lapped 99 times atpiles of sandbags placed to guard the doorways of the Doges' Palace and St.Mark's Basilica. More and more frequently, visitors must walk on elevatedwooden walkways, or passarelle, as peak tides flow over the city'ssidewalks. Boats cannot navigate the canals during the highest tides becausethey cannot pass under bridges.
The high tides are not just annoying but damaging. Instead of merely washingagainst the impermeable marble that makes up the city's foundations, highwaters are splashing with increasing frequency against the soft, permeablebricks that sit above the foundations. Saltwater from the Adriatic soaks intothis brick, inching ever higher into the walls and creeping into interiors,destroying frescos and other irreplaceable relics. Unless they have beenrestored with new, waterproof brick, many of these buildings crumbleimperceptibly.
What can be done about this unstoppable rise in sea level, which brings thewaters of the Adriatic, borne on twice-daily tides, higher and higher againstthe stones of Venice?
Gates of salvation?
City officials, the Italian government, and a consortium of Italy's largestconstruction and design firms believe they have the solution to this messyproblem: line the bottom of the Venetian lagoon's three entrances with a seriesof 79 hollow steel gates that would be raised to hold back the sea in times ofacqua alta.
When tides are low and weather calm, these gates would be filled with water andrest on the bottom of the three channels at the north and south ends of theLido—the long, narrow island that separates lagoon and sea—and at thefishing village of Chioggia on the lagoon's southern end. When storms withstrong winds roam northeasterly across Italy and Adriatic tides run high,engineers would activate a system that pumped compressed air into the gates.The air would force out the water, enabling the gates to rise on hinges andform a barrier against the surging seas.
Project MOSE, the acronym for the experimental model created to test the gates'performance (Modulo Sperimentale Elettromeccanico), has been the onlyproposal proffered by engineers, contractors, and consortium scientists sincethe early 1970s. (Watch a video about the proposed gates.)
In December 2001, the government announced plans to build the gates at a costof between $2 billion and $3 billion. Supporters of the project said designwork would begin this fall (2002), with construction getting under way within afew years. The most ardent supporters said they believed the gates would be inoperation between 2007 and 2010. On September 23, 2002, however, the VeniceCity Council voted to reconsider its support for the gates and raised thespecter that the project should be reevaluated. This was stunning news, andwhether the project will ever regain its standing remains in doubt.*
It is political reality in Italy that governments do not lastlong; 58 governments have come and gone since 1945.
The project has long had a bevy of critics: Italian and internationalenvironmentalists, along with scientists who for three decades havedisapprovingly followed the path to the MOSE solution. Those opposed believethat relentlessly rising seas will make MOSE obsolete within a few years. Theyalso worry that officials would need to raise the gates so often that thenormal ebb and flow of the cleansing tides would dramatically affect aquaticlife within the lagoon and make the city unlivable for long periods, as sewagenormally flushed from the lagoon remains behind. These critics want morestudies conducted on the gates' potential environmental impact, and they wantthe international scientific and engineering community to come up with newsolutions that would protect Venice for the next century rather than for justthe next few decades.
Even if gates advocates can somehow reverse the stance of the Venice CityCouncil, the national government faces many other hurdles before it could everconsider construction. First is the question of financing the project. Thecurrent Italian government, in power since early 2001, has also announced plansto rebuild the nation's freeway system, expand the national high-speed trainsystem, and construct a suspension bridge from the Italian mainland to Sicily.All this comes at a time of budget crisis and no identifiable means of raisingthe billions of euros needed to launch these projects.
Italians tend to wink at such grandiose pronouncements. It is political realityin their country that governments do not last long; 58 governments have comeand gone since 1945, and new elections will likely take place by 2004. Anadministration that does not support these projects might well come topower.
Tide of optimism
But through this climate of political infighting and uncertainty, hope forVenice springs eternal. City officials backed by the Italian government havequietly appropriated significant sums of money separate from the gates projectto improve the infrastructure of the historic center. Crews are dredging acentury's worth of accumulated muck from the city's dozens of canals and arerebuilding and waterproofing canal sides. They are restoring bridges andfountains. And they are raising fondamente, or sidewalks, along thecanals and edges of the surrounding lagoon to levels above routine high-watermarks.
Plans are afoot as well to improve Venice's treatment of sewage, which forcenturies has been dumped directly into the canals. Venetians are nowinstalling septic tanks as buildings and market areas undergo renovation, andauthorities hope that within the next two decades, traditional sewer pipes candeliver the city's waste to mainland water-treatment facilities. Finally, St.Mark's Square, the city's lowest point and most frequently flooded area, isslated for a $50 million project to rebuild its drainage system.
The debate over how to safeguard Venice and preserve its buildings and arttreasures for successive generations will not end soon. Indeed, it will likely beyears before construction of any kind begins, whether of the mobile gates orsome entirely different solution.
*On May 15, 2003, Silvio Berlusconi, Italy's Prime Minister, officially launched the gates project, which is expected to take eight years to complete at a cost of $4 billion.
To visitVenice's famous St. Mark's Square in times of flood, you have two choices: walkwith everybody else on raised walkways called passarelle...
...or go it alone amid the rising waters.
The worst acqua alta in memory, the one thattruly woke Venetians up to how bad things could get, occurred on November 3,1966. The high tide that swept into all corners of the city that night lastedan astonishing 22 hours (typical high tides last six).
Designers say that the proposed mobilegates, when raised into their upright position (as pictured above), would holdback the incoming tide up to a level of six feet or more above the water levelin the lagoon.
How wet will Venice get in the comingyears? Only time—and the result of ongoing passionate debate—willtell.
