Climate Change and the European Water Dimension - Agri ...

Chapter VI.B. Climate Change and the Venice Lagoon
VI.B.1. Why Venice? A historical insight
The Lagoon of Venice, the largest in the Mediterranean region, is a compendium of
almost all the problems facing these environments: the unique characteristic of
Venice is mainly to have survived in spite of the co-presence of all of them. For over
five centuries the continuous intervention of man has allowed Venice to be preserved
along with the “lagoon status” of the environment around it, overcoming the “natural
changes” occurring during this period. Meanwhile, other tidal lagoons of the Adriatic
Sea were “naturally” silted from the sediments carried by the rivers (or eroded by the
greater relative force of the sea, and transformed from wetlands into a marine bay).
In the Venice lagoon, huge engineering works, starting in the 15th century, were able
to divert most of the river outlets from the lagoon to the sea and so maintained the
“water wall” around the city, essential for defence reasons, and for Venice’s strategic
economic role as a city-port. The last big and very expensive public works
undertaken by the Venetian Republic was the building of the sea defences (Murazzi)
along the coastal strip, at the end of the 18th century, completed only two years
before surrendering to Napoleon’s Army. More recently, the long jetties built between
the late 19th and early 20th centuries determined the current form of the three inlets.
To facilitate Venice’s economic development, a large industrial area at the lagoon
margin was created (Marghera); beginning in about 1910, deep canals were also dug
through the lagoon to connect the new port to the inlets, and artificial islands were
constructed for further industrial growth. Fish farms have also been developed in the
north and south of the lagoon, closing areas of the lagoon to tidal expansion. A few
decades ago, the Venice international airport was built on reclaimed land on the
lagoon’s margin. Other land has also been reclaimed to facilitate extension of the
industrial zone, housing development and agriculture.
In recent years, after the great flooding event of 1966, the future of Venice received
much attention, following decades of neglect as regards urban maintenance. Many
scientific and technical institutions have produced countless reports. Since 1973 the
Italian Government has supported large environmental and socio-economic
programmes and is presently launching a 4-billion € programme (to be concluded in
2012) mainly addressing safeguarding the city from sea level rise. The efforts of the
Italian State were addressed not only to reinforce the old sea defences or to
implement other new essential works in the lagoon, the city and in the drainage
basin, but also to strengthen the research infrastructure and to sustain its activity.
VI.B. 2. Brief Description
The lagoon of Venice, with a surface area of about 550 square km, of which 418
square km are open to the tides of the Upper Adriatic (the widest tidal range in the
Mediterranean), is the largest Mediterranean lagoon. The sea and the lagoon are
connected through three inlets: Lido, Malamocco and Chioggia. The coastal barrier
stretches for a total of about 60 km. About 78% of the lagoon surface is submerged
by water, which are crossed by a dense network of channels of varying depth. The
lagoon is subjected to heavy anthropogenic pressure, which increased greatly during
the last century, following large scale urban, industrial and agricultural development.
The “closed lagoon”
The part of the lagoon not subjected to the tide (“closed lagoon”) includes all of the
fish farms with their internal islands, along with mud flats and salt marshes. Typical of
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