Stemming the flood
Venice is a remarkable city, with a tremendous appeal to the senses and the emotions.
Shelley wrote of it in 1818: Underneath Day’s azure eyes / Ocean’s
nursling, Venice lies, / A peopled labyrinth of walls, / Amphitrite’s
destined halls.” Today there are grave doubts over the ability of the
authorities to preserve this gem of the Adriatic, in the face of repeated threats
from the primeval elements.
The city sits in a lagoon separated from the Adriatic Sea by nothing more substantial
than a string of barrier islands . When the terrain consisted of mud flats rising
tides tended to be dissipated. But after humans had diverted rivers, widened
the mouths of lagoons, drained channels and built on the flats, equilibrium was
upset.
Today, in a sea surge, there is little to protect the streets and squares from
floods, and the city regularly experiences winter floods. In November 1966 a
period of incessant rain for two days, a prolonged low-pressure system, causing
the sea level to rise dramatically, and a powerful wind forcing waves into Venice’s
canals, resulted in alarming flooding.
In 2001 engineers proposed possible solutions, including the construction of
78 hollow metal gates, each 20m high and 5m thick, at the three main inlets of
the lagoon. These would normally lie flat, but could rise when inflated with
air to meet the emergency of a high tide. Construction of these gates is planned
to be commenced in 2006 and completed by 2011. Meanwhile, stone reefs are devised
to counter oncoming tides.
There have been many arguments over the scheme, which might upset the ecosystem
of the lagoons and will certainly be expensive. If, as some argue, a freak flood
might occur only every 165 years, it would waste resources. And environmentalists
fear that the sea-grasses of the lagoons might become choked by mud. Prolonged
gate closure would impede the flow of sewage from the city, some argue, while
others think that natural tidal clearance would continue, even if gates had to
be closed for five days.
In an effort to achieve objectivity, an international meeting to discuss the
Venetian problem is planned for September in Cambridge. Yet many remain worried
over what might happen during the period between deciding on plans and implementing
them. Nous verrons!
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This is important, since in most parts of the world malarial parasites have
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which has for long been the main standby.