[Acqua Alta in Venice, Italy by REUTERS/Manuel Silvestri]
The seriousness of rising sea level is apparent today as we see many coastal cities are building new flood-defense systems and flood-resistant buildings. In March of 2010, the Maldives government and Dutch Docklands/Dutch Water-valleys signed an agreement to develop floating structures; and by 2015, five artificial floating islands will be completed. New York revised their building codes for new buildings to be watertight in flood-risk areas. St. Petersburg’s new flood barrier, which is capable of protecting the city from a “one-in-1,000-year flood,” will be completed next year.
Venice in Italy, often called the “floating city,” is not an exception. Venice is one of the low-lying coastal cities which are most vulnerable to the effects of rising sea level. According to this diagram (see figure 2), Venice will be completely underwater if sea level rises to 2 meters. A report says that Venice may be submerged completely in less than 100 years at the current rate of the rising water level in Venice lagoon. This means that although we may still be able to visit Venice in our life time, our offsprings may not be able to visit Venice.
Venice has always experienced occasional floods resulted from Acqua Alta (Italian word for “high water,” a phenomenon of exceptional tide peaks that flood part of Venice and occurs mainly between autumn and spring). This exceptional high tide can bring the water up to more than 140 cm; and it happens about 18 times February (detailed info). Acqua Alta causes damages to buildings and inhabitants. For many times, merchandises and products are damaged in retail stores on the first floor because of the flood; and “no Venetian lives on the ground floor any more.” As the sea level continues to rise even more, the city might become uninhabitable at all.
In the 20th century, Venetians drilled many artesian wells around the edges of the lagoon for the demand for waters. Draining out water from the wells caused the city to sink on its own land. Artesian wells were banned in 1960s as the government realized the depletion of the aquifer was causing the sinking. Although the sinking stopped after the ban, Venice sank 11 inches and the city is to submerge into water even faster because of it.
Venice is currently under construction for building a flood barrier system called “MOSE,” a project consisting 79 floating barriers to block the lagoon from the Adriatic Sea when high tides are forecasted. This project underwent 30 years of debate and testing until it was finally inaugurated in May 2003. In 2006, the project was “under review” for budgetary reasons. The completion date is now extended to 2014 from 2011. The project costs 4.3-billion-euro (MSNBC).
[MOSE project - http://www.sharenator.com/Engineering_Feats/#/venice3-2.html]
However, this project has always been controversial as it inherits many problems that suggest it may not be the best solution for Venice. The project is irreversible and outdated. The project did not consider the predictions of rising sea levels over the next centuries into its equation. According to Sylvia Poggioli’s article, “MOSE engineers responded that the mobile gates are designed to last at least a century and to protect Venice from a difference in water level between the sea and lagoon of up to six and half feet.” But as the rate of rising of sea levels increases, the project’s life may become shorter and will eventually need another solution to replace it. Also, the barriers will close the lagoon too often as Acqua Alta occurs more frequently, which will stop the flow of water of the lagoon. This can damage the health of the ecosystem and make the lagoon more vulnerable to flood. Although the project still undercurrent despite the controversy and flaws of it, Venice must seriously consider alternative solutions that can sustain Venice for more than a couple of decades.
Rather than building barriers to enclose the city from the outside world (Adriatic Sea), Venice should consider building a new “floating” community. Although floating community may sound too radical, such utopia already exists in Netherlands. Maasbommel in Netherlands has neighborhoods built with floating housings. Even worse than Venice, half of its land mass is only 1 meter above sea level. “Dutch Floating Homes,” designed by architecture firm DuraVermeer, rest on land but is built to rise when the water rises. The houses can float up to as much as five and a half meters, responding to the height of water level. Each of the houses are built on the hollow concrete cube base that contains air to allow floatation by its buoyancy. This allowed the Dutch to stay near and live with the water. Venetians should look into the Dutch floating housings to see how that can apply it to their city.
In Graduate School of Design in Harvard University, a student thesis project was proposed for housing for Venice which used same base-technology of “Dutch Floating Housing.” The project proposed modular housing system that can configure to aggregate to build a community. Each housing unit is built on stilts and when the water rises, the air-tank below the floor slabs allows the building to rise with the water levels(see the image below). Although its complexity in form is intriguing, the project lacked contextual coherence with Venice.
[Housing for Venice - GSD thesis project 2009]
This student project is rather more suitable for Maasbommel as Maasbommel is a suburban residential area. For Venice, the floating community must not only address the housing, but also the retail stores. The city of Venice is organized differently than Maasbommel. Unlike Maasbommel, Venice’s public zone exist in the same building as private zone. For example, ground floors are usually occupied as retail stores and public areas while upper floors are occupied as residential apartments and hotels. Venice has close relationship between the public and private zones. By including public zones in this new floating community, this new Venice will keep Venetians to live in Venice and continue supporting tourism. Therefore, each floating building units will consist more than one floor to keep the first floor for public use and upper floor for residential use. The community should continue to advocated pedestrian and boat transportation by creating canals and bridges.
Besides the rising sea levels, the sewage conditions in Venice is another serious problem in Venice that has to be solved. For several hundred years, black-water was drained down directly to the lagoon mixed with chemicals which tremendously damaged the fragile ecosystems of the lagoon. Venice still has no sewage treatment facilities; and toxic components of untreated wastes are still dumped into the lagoon. To build a completely sustainable community, a new sewage treatment system must be factored into the design as well. By providing an efficient sewage system, the “new” Venice will be a big leap of its evolution finally after its several-hundred-years-old sewage systems.
Because the city has long been completely dependent upon boat transportation for bringing in goods into the city, all of their goods are transported by boat, which makes “everything” expensive in Venice. Several years ago, the tourists and locals had separate prices for products--the tourists paid taxes. However, now even the locals are required to pay the tourist prices. Thus, it is hard to Venetians to survive to live in Venice. Many Venetians moved out the city to live in other cities because of its expensiveness. If the new community can provide new urban farms to produce their own goods, it will help the products to be affordable to the locals. In terms of public transportation, Venice is a sustainable city as it advocates pedestrian and boat transportation. There is no vehicular transportation system. The new floating community should continue to advocate such sustainable transportation system as carbon emission is biggest issue of global warming.
Such community will be more suffice to Venice than building barriers to block the city from its closest and oldest friend--the water. This is not an issue just for Venice. Many coastal cities needs changes of the way people live, the way buildings are designed and built to cope with our changing world and rising sea levels. By rethinking how we live and build communities, we can still continue to live closely with rising water and still benefit from it too.
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