Monday, October 26, 2009

New Orleans Can No Longer Be Protected From Storm Surges

From the Guardian.UK:

New Orleans can no longer be protected from hurricane storm surges, according to the US army general in charge of the city's defences.

General Robert Van Antwerp, chief of the US Army Corps of Engineers, said his team was in "persistent conflict" with the Mississippi river.

"If you ask can I protect the city, the answer is no. Can I reduce the risk? Yes.

"We can develop better early warning systems, better evacuation plans, better levees to hold back most of the water, but we cannot stop levees being overtopped and the city flooded."

He declined to say whether this meant the city should be abandoned altogether and relocated inland. "That is outside my brief," he said.

Four years after Hurricane Katrina devastated New Orleans and caused a political crisis for President George Bush, a religion, science and environment conference in the city was told that half of Louisiana will be lost by the end of the century.

The vast Mississippi delta is sinking a centimetre a year. Sea levels are rising at an accelerating rate, and will be two metres higher by the year 2100. Much of the delta is less than a metre above sea level, so most communities will be submerged.

The oil and gas industry's massive canal and pipeline network, which provides 35% of the country's gas and oil, cuts through the state's freshwater swamps and marshes, allowing vast quantities of sea water from the Gulf to wash into the delta and kill many of the trees and plants that protect the land from storm surges.

Chris Macaluso, in charge of the newly created Office of Coastal Protection, says 2,300 square miles of marsh and swamp have been lost because of salt-water intrusion in 50 years.

In the four-month hurricane season, land disappears at the rate of an acre every six minutes or 25 to 40 square miles a year.

His office is reconstructing some of the barrier islands along the Gulf to protect the remaining wetlands from wave action, but what used to be marshland behind them is now open water dotted with oil wells. Most of the once vibrant cypress forests, which could stop the storm surges, are reduced to dead stumps sticking out of the water.

"We have broken the ecosystem. What we are doing to restore it is a drop in the ocean of what is needed," Macaluso said.

His office is spending $1.5bn (about £915m) over four years on wetland restoration. Another $14.3bn is being spent on new levees and defences for New Orleans.

It is estimated that to save the delta's wetlands and its settlements from sinking by diverting the Mississippi would cost $200bn.

Prof Gerald Galloway, from the department of civil engineering at the University of Maryland, said: "We are facing catastrophe. The challenge now is to see if anybody will do anything about it."

Dr Peter Bridgewater, chairman of the UK's Joint Nature Conservation Committee, asked if he would advocate evacuation of the city, said: "New Orleans is not a place to invest in real estate.

"There needs to be dramatic changes in policy and attitude, but time is running out."

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