FEATURE: Venice: Death among waters

Since its origins, Venice has always been bonded to the waters of the lagoon that surrounds it. The sea has been the main source of wealth of the city during the over 1.000 years that existed as an independent republic. However, nowadays the main threat of Venice is the sea-level rise. Now, a titanic project attempts to save from sinking one of the most amazing cities on earth.

The capital of the Veneto is unique, and no other city in the world can equal her unreal disposition in the middle of the lagoon, less than one km from the Italian dry land. Venice was built on 118 islands, it has near 400 bridges and its canals cover an extension of 90 km.

The origins of the city of Venice date back to around year 421, when some inhabitants of the Veneto region, harassed by huns and lombards, established a small community in the islands of the lagoon. After the Bizantine campaigns in italian land during the 6th century, Venice became a Bizantine posession, despite preserving some autonomy. Two centuries later, in 721, the city elected its first Dux, establishing a republic that would last one thousand years. The development of an extensive network of maritime trade provided wealth and power to Venice, whose situation in the middle of the lagoon made it almost impregnable. It survived in 810 the fleet of Pippin the younger, son of Charlemagne, and the genoese army in 1380, thanks to the sea, and to commemorate her link with the waters, the city celebrated, every year since 1173 until the fall of the republic in 1797, the traditional ceremony of marrying the sea, whereby the Dux sailed to open sea and threw a gold ring to the waters.


Venice, Mediterranean power

In 1204, and thanks to the fourth crusade, Venice increased its empire annexing former Bizantine territories, and its power raised in subsequent centuries. Later, the territorial ambition of the republic, its expansion towards the Italian dry land and the wars where it got involved marked the beginning of the commercial and politic decline of the city. In the dawn of the 18th century, even though it had lost most of its overseas possessions, Venice extended from the Cadorino in the north, to the duchies of Modena, Parma and Bolonia in the south; and from Bergamo in the west to Istria, Dalmatia and some islands in the Aegean, in the east. In 1797, however, the army of Napoleon Bonaparte conquered the city, ending one thousand years of venetian independence.


Projects

Throughout the long venetian history the waters have saved the city several times from mayhem and destruction. Today, nevertheless, the water is the main threat to the city. The muddy terrain is sinking, while the water-level rise is more worrying every year. In 1966 Venice suffered the worst floods in decades. That summer the water level increased 1,94m in the lower parts of the city, such as San Marco square. Venice suffers constantly small floods, called "aqua alta". Every time this happens, the salt from the open sea erodes the wood pillars that sustain the city. In the 20th century Venice sinked 24 cm and a worst forecast is expected for the 21st century.

To avoid the sinking of the city, in 1975 the Ministry of Infrastructure organized a contest aimed at finding a project which could save Venice from the waters. Finally, the project by the Consorzio Venezia Nuova was chosen. In 1989 a preliminary project was carried out with the main objective of regulating the tides, called REA (Riequilibrio e Ambiente). In the following years some studies about the feasibility and viability of the project were also carried out and finally, in September 2002, the consortium presented the definitive project. The works started in 2003. The project is divided into three different fields of action: high water defense system, defense against tides and recovery of degraded environmental spaces.



The Project Mose

The so-called Project Mose (Moses in Italian) is the most important part, which concerns the regulation of the high waters The project consists on the construction of 78 mobile gates on the lagoon bed in each of the three lagoon inlets (Lido, Malamocco and Chioggia). These gates will open or close depending on the height of the tides, so when the tide is low the gates will remain closed, resting on the lagoon bed, allowing the normal flow of water in the lagoon. In case that the tide reaches 1.10m, and up to a maximum of 3m, the system will be activated and the gates will be lifted, avoiding floods.


Source: The telegraph

The operation of the Mose System is based on the placement of the different barriers that range between 20 and 30m long, in the lagoon bed, some 15 to 20 m deep. When the tide reaches 1.10m, compressed air will be blown into these flap gates. This will eject the water out of the gates and will lift them some 45 degrees, stopping the tidal flow of the water from the Adriatic to the lagoon. When the high tide ends, which normally lasts between four or five hours, the gates will be filled with water and will return to their original position on the lagoon bed. The project, which will cost around €4,600 million, is expected to be finished by 2014, though it was due to be completed in 2012.


Criticisms

According to the Consorzio Venezia Nuova, the effectiveness of the project is guaranteed. However, parts of the project have been criticised since its approval. Some political forces argue that the cost of the whole project is unsustainable for the Italian economy, especially in the current economic situation. Ecologist groups warn that it will cause a huge impact to the environment, given that the floodgates will alter the ecosystem of the lagoon, interrupting the natural cycle of the tides, and warn that it is an irreversible project. The Consorzio Venezia Nuova argues, however, that in 1998 an environmental impact study was carried out and given a possitive assesment by experts on the matter.

On the other hand other groups have proposed alternative solutions, more respectful with the environment. A group of engineers from the University of Padua defend the feasibility of lifting the whole city of Venice through the injection of water at high pressure in the subsoil, 700 metres deep. In any case, the only certainty is that Venice sinks further everyday.

By CDR with No comments