Venice saved from the waters
Francesco Erbani
Francesco Erbani ends his series of essays about Italian landscapes with an article about the Venice Lagoon, featured in 20 September 2003 Repubblica; here, perhaps for the first time, voice is given to the point of view of MoSE adversaries. Below it, a box about “The reasons in favour of MoSE”. We are confident that when the newspaper will talk about the activities of “Consorzio Venezia Nuova” (New Venice Consortium – the firm appointed for the building of the MoSe), it will publish a box for “The reasons in favour of the Lagoon”, too.
It is uncommon for a man from the South, accustomed to horizons defined by rocks and cliffs, to come to love the boundless span of a lagoon landscape. Yet Edoardo Salzano from Naples, 73 years, urban scientist, former university professor and Faculty president, has been living in Venice for almost 30 years and has grown a true fondness for the Lagoon. He is a guardian of the lagoon because he has been studying it for a long time and for a long time has been refining tools to protect it and to spread public awareness. To Venice - where he has also been councillor - to its islands, to its fauna and vegetation, to its branching outline and to the menaces that threaten it, he has dedicated one of the most popular sections of a website opened some time ago and that has become a rich repository of news, opinions and forums about city planning, landscape and urban sciences (www.eddyburg.it).

To Mr Salzano’s eyes the lagoon is precious for its salt marshes and the play of tides which makes them rise and sink. For its major islands (Murano, Burano, Torcello, San Francesco del deserto, Pellestrina, Sant’Erasmo), the Lido and the minor islands, on which Venetians built monasteries and hospitals and where cargoes and sailors were quarantined. For its lights that show gradients from pink to the darkest red at the sunset. And also because it is a laboratory. “It is the result of the smart application of human action to nature”, he explains, “an application that uses tools like time, tidal flows, lunar phases. And constant maintenance, always building different arrangements”. A representative case, that is. Very much modern.

The lagoon is not a stable element. “It is a passing phase, a moment of passage in the conflict between river waters, that bring mud, and sea waters, that tend to bring that mud away from the basin. If the river forces win, the lagoon becomes a pond; if the sea forces win, it becomes sea”. Venetians wanted to preserve the lagoon for economical reasons. It was needed to build and repair ships in quiet waters. And, with its fishes, it was a source for food.

“The Venice Republic has maintained this balance for centuries. Giovanni Astengo, great urban scientist, often mentioned a channel called “of the scomenzera”. In its name was the method: every time that some work in the lagoon was started (“scomenzar”, for “cominciare”, “to begin”) everyone would monitor its effects. The work was continued only if the consequences were not harmful; otherwise it would be started over”­.

And then, the equilibrium has gone. The most obvious symptom of this disruption is the high water phenomenon, which, in certain weather conditions, floods parts of Venice’s historical center. The lagoon has shown his hostile face (the terrible flood of 1966). But high water is not an illness that the city has been carrying for centuries, it is not a natural pathology caused by the fragile coexistence of land and sea. High water is an historical illness, Salzano points out. Until 1962 – according to the Consorzio Venezia Nuova, source of an impressive deal of historical studies and territory history – high water has never been an alarming event: during the decade of 1953 the lagoon level has exceeded 110 cm only 18 times. After 1962 the floods suddenly increased: 32 in the decade until ’72, 37 in the next. In the 1993-2002 decade they soared to 53.

If this is an historical problem and does not depend from the lagoon physiology, which are the causes for high water? One is to be found in the Luigi Scano (“Venezia terre e acqua”, 1985) and Piero Bevilacqua’s (“Venezia e le acque”, 1995, new edition 1998) books. The story begins during the sixteenth century, when Cristoforo Sabbadino, water technician for the Republic, called for a series of urgent works to give back the lagoon its maximum capability, avoiding any work that could reduce its capacity: the “sovracomun” (“over city”), as the high water was then called, was not caused by the sea level rising, according to Sabbadino, but to the narrowing of the basin due to the debris left from the ingoing rivers. For this reason, in the following decades many river mouths were deflected out of the lagoon and all obstacles to the water intake and expansion were removed. Strict measures and harsh penalties were adopted against those who interred parts of the water surface to obtain land or rise banks or dared to privatize marshes to start a fishing farm.

“Venice learned to live in a vulnerable environment. It gained knowledge and know-how, which became the basis of its strength”, Salzano says. Its heroes where water technicians, fishermen and wood cutters. Upon their knowledge a managing class established, which guaranteed to the city continuity of government and richness. “The amphibian condition drove Venice to pursue natural safeguard techniques, without forcing, even when “great works” were needed: the deflection of rivers, the building, in 1744, of the Murazzi, a stone barrier which runs along the lagoon’s external border”. When, at the end of the 18th century, the autonomy of the Republic crumbled, Venice took another path. During the 19th century channels and streets were dug in the historical center, reducing the basin capacity. In the 1917, then, the industrial adventure of Porto Marghera was started, which brought lots of poisons and caused the drying of more lagoon areas. According to Scano’s figures, the lagoon basin has lost 7 thousand hectares during the last decades, while 8 thousand more have been subtracted by the fishing basins barriers: about a third of its whole surface. At the same time, the port mouths were deepened and channels were dug in order to allow ships to reach the port. Around 1965, at the Malamocco port mouth, the depth reached 57 meters, to allow oil tankers to load and unload crude from Marghera depots.

These two conditions – narrower lagoon, shallower seabed – are upsetting the past equilibrium and are quickening the flow of sea into the lagoon, Salzano explains. It is as if a faucet was completely opened to let water enter a recipient were some joker had put several stones: the water flows out and this is how Venice is submerging.

In order to contain high waters, in the late 80ies, the MoSE (Electromechanical Experimental Module) project was started. The first stone was posed by Silvio Berlusconi last may. MoSE is a mobile dam system built at the port mouths of Lido, Malamocco and Chioggia. A great concrete structure will be set upon the sea bed, upon which mobile barriers will be mounted. The barriers rise whenever the sea level exceeds 110 cm and stay up as long as the condition lasts, then they sink back.

According to the technicians of Consorzio Venezia Nuova (the pool of companies that designed the project) the use of the mobile barriers will be sporadic. They will rise, they assure, 3 to 5 times a year: this is the number of times that, in average, the sea level has exceeded 110 cm (but, the same sources say, in December 2002 alone the limit has been exceeded 15 times). No problem, they swear, for the lagoon life, that needs a constant water exchange in order to not become a lake, which would mean death; and the lagoon’s death means Venice’s death.

Salzano is a MoSE antagonist (and like him the most part of the environmentalist front: Italia Nostra of Venice has built a massive dossier). To his eyes, apart from technical matters, MoSE is a great artefact that conflicts with the history of natural maintenance that Venice can be proud of. It is an extremely expensive work, he adds: 2,300 millions euros for design and work (3,700 millions according to other sources); 9 millions euros a year for management and maintenance. Moreover, he insists, “it is not sure it will work and we cannot afford a “great work” at those prices that does not even guarantee positive results” (the MoSE examinations begin during the nineties: positive vote by an international expert committee – July ’98 – and by the Region – October ’98; negative vote – December 98 – by the Environmental Impact Evaluation Committee, canceled later by the Regional Court for a formal defect).

The dispute about MoSE has been going on for years. It divides technicians and political sides (the arguments in its favour are summarized below). The dams should start working in 2011. Until then Venice will have to live with high water anyway. “The work will heavily impact the lagoon”, adds Salzano. “Huge blocks of concrete will be laid on the sea bed, and they will sever the continuity between the lagoon and the open sea”.

A real alternative to MoSE does not exist. Nothing that is so technologically striking, anyway. The alternative calls for a different idea of Venice, it builds its reasons upon the causes for high water, with the purpose to remove or at least decrease its effects. Already during the first Massimo Cacciari administration two operations have been started, and they are continuing under Paolo Costa: the cleaning and digging of the rii (channels) now obstructed by debris and waste, in order to restore their former capacity and allow more room for water expansion; and the elevation of the city surface to a quota of 120 cm. These “cuci e scuci” interventions (stitch and unstitch), as Salzano calls them, are what Venice and its lagoon need. Salzano refers to the Great Masses Laboratory of CNR (Research National Committee) according to whom these and other “small works” (reopening of obstructed lagoon zones, seabed reshaping, rebuilding of the texture of natural channels, for instance) could reduce the high tides of an average 20-25 cm. “That would mean”, says Salzano, “that the frequency of high water would decrease to a few days for year, as it always has been since Venice is Venice”.

The defense.

The reasons for MoSE

There are several arguments in defense of MoSE. According to the technicians who are building it, during the 20th century the lagoon bed has sunk more than 23 cm relatively to the sea bed. This is due to the increase of the sea level (eustasy) and to the lowering of the land (subsidence). These are, according to the technicians, the main causes for high water. The digging of the oil tankers channel has been one of the causes for lagoon degradation, but it had no consequence on the phenomenon. It suffices to think, they add, that at the time of the 1966 flood the channel has not yet been dug.

The hypothesis that the opening of the fishing valleys and the filling of the oil tankers channel could decrease the tide levels inside the lagoon, according to the MoSE technicians, has been put under analysis. But results show that these interventions cannot have effect upon high water. Moreover, the lifting of whole land areas is not sufficient, because great doubts remain about methods and results. Such interventions, above all, would not insure a uniform lifting. They are hence unthinkable in such valuable and fragile historical centres as those of the lagoon cities.

Sullo stesso tema
Paolo Pirazzoli
Una utile sintesi dei principali errori tecnici del MoSE nel documento presentato dal movimento NOMOSE a Copenaghen, al meeting sul clima (marzo 2009). Also in english
AA.VV.
by Edoardo Salzano and Anthony Zamparutti. Paper presented and distributed at 37th International Making Cities Livable Conference, Siena, 15-18 June 2003.
Italia Nostra
Why the natural balance was broken, in a synthetic document (one of three, edited by Lidia Fersuoch) of Italia Nostra, Section of Venezia (2003)
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