Image: 2008 flooding in Venice
Luigi Costantini  /  AP
Water levels in Venice, Italy, rose to their highest level in more than 20 years last winter. In December 2008, the water covered a cafe's table and chairs in the city's famed St. Mark's Square.
updated 9/7/2009 6:24:53 AM ET 2009-09-07T10:24:53

Italian authorities plan to expand Venice's port into a bustling shipping hub, further endangering the fragile lagoon and contributing to the sinking of the treasured city built on water, a conservation group said Monday.

Venice in Peril, a British fund that works to preserve Venice, said a report it obtained from the local port authority showed plans to accommodate more and bigger ships in a bid to compete with other European harbors.

The Venice port authority confirmed it had written the report, but insisted the works will respect the environment and are necessary to deal with the growing flow of tourists and goods.

The debate illustrates the complex and often controversial balancing act between protecting the UNESCO world heritage site and exploiting a sea port that gives easy access to prosperous areas of northern Italy and central Europe, as well as rapidly developing markets in the Balkans.

The report drawn up for the Italian Senate outlines ongoing and future works including the continued dredging of passages in the shallow lagoon to allow larger vessels in and the construction of a new shipping terminal in the long-declining mainland industrial zone of Porto Marghera.

The port authority is spending at least $370 million to dredge inlets and navigation channels to allow the passage of ships of up to 1,300 feet in length.

This is particularly concerning for conservationists because dredging and heavy ship traffic are seen as one of the causes of the rising sea level in the lagoon, which threatens the low-lying islands on which the historic city is built.

"The fact that big ships have access to the lagoon has important consequences for its health," said Jane da Mosto, a researcher for Venice in Peril. "Apart from environmental concerns ... the problem of high tide is accentuated, so it means more flooding for Venice."

Rising sea level causes problems
Under the combined effect of rising water levels and settling of the land, Venice has sunk nine inches in the last century.

Most experts agree that the waves generated by large ships and the currents that run through the deep passageways play a big part, displacing and dragging out to sea the sandbanks and other sediments that help keep water out.

In winter, Venice periodically goes through bouts of "acqua alta" (high water), when strong winds and high tides conspire to push the sea into streets and piazzas, forcing tourists and locals alike to don rubber boots and teeter along impromptu bridges.

The rising sea level has increased the frequency of the floods, and in December, Venice suffered its worst deluge in 22 years. Experts warn the problem could further worsen in the coming decades as climate change causes sea levels to rise globally.

‘Moses’ system to prevent flooding
The port authority report dismisses environmental concerns by declaring them solved thanks to a project to build towering movable barriers designed to rise from the seabed and prevent flooding.

The $6.13 billion system, named Moses after the Old Testament figure who parted the Red Sea, is expected to be operational by 2014.

"The problem of the hydraulic equilibrium is solved because it will be manageable through judicious use of the Moses system," the report says.

Not so, some experts said.

The Moses barriers block shipping so they would only be raised when an exceptionally high tide is expected. That would not lower the average sea level and stop the waters from slowly eating away at Venice's bricks and stones, said Luigi D'Alpaos, professor of hydrodynamics at the University of Padua.

"Moses will, at best, manage the acqua alta," he said in a telephone interview. "But the other problems are not at all addressed by the barriers."

Officials at the Venice port authority said the dredging is needed to restore the navigation channels, which are filling up with silt, to their original depth. They said the digging will not go beyond the depth allowed by law and any expansions on land will be done within the existing port zone.

But Venice in Peril said work should be done instead to reduce the depth of the channels, where possible, or at least reconstruct the natural lagoon features that protected the city for centuries.

More on: Venice

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