THE BLOG
03/18/2010 05:12 am ET Updated May 25, 2011

US Army Corps can't stop floods in New Orleans

Lt. General Robert Van Antwerp, Chief of the US Army Corps of Engineers would not answer my question "Should New Orleans be abandoned?"

But the General, whose job it is to protect New Orleans from future hurricanes, did admit he could not save the city from storm surges. "Protect the city no, 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."

Evacuation and retreat from the sea in Louisiana is the central question concerning the Corps and the rest of the delegates attending the Religion, Science and Environment Symposium in New Orleans.

How to save not just the city but the southern half of Louisiana from the combined effects of man's past mismanagement, subsidence of the delta, and ever increasing sea level rise?

The Mississippi Delta sinks around an inch every 30 months and with sea level rise accelerating water levels across the delta will increase six feet this century. With much of the delta less than three feet above sea level most communities will be drowned by 2050, leaving New Orleans, if it survives at all, a vulnerable island behind its levees.

Man's share in the destruction has been mainly the oil and gas industry's massive canal network. Canals cut through the fresh water swamps and marshes allowing vast quantities of sea water from the Gulf to wash into the delta killing many of the trees, plants and animals that protected the land from storm surges. This is the way America gets 35% of its gas and oil.

The figures of losses in the delta are startling. 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 criss-crossed with pipelines. Most of the once vibrant Cyprus forests, which could stop the storm surges, are reduced to dead stumps sticking out of the water.

"We have broken the eco-system. What we are doing to restore it is a drop in the ocean of what is needed." His office is spending $1.5 billion over four years on wetland restoration. Another £14.3 billion is being spent on new levees and defences for New Orleans. Estimates of what it would cost to save the delta's wetlands and its settlements from sinking are estimated at $200 billion in the state governor Kathleen Babineaux Blanco's "Louisiana's Comprehensive Master Plan for a Sustainable Coast."

This calls for the diversion of the Mississippi, basically breaching the levees that keep the river flowing to the Gulf, so that the sediment spreads over the delta and heals the eco-system by allowing it to re-grow.

To allow river diversions the Corp of Engineers needs to modify its main priority which has been to keep the Mississippi open to navigation at all times. The river carries 11% of the America's trade, with New Orleans as the country's largest port, and is vital to the nation's economic welfare.

The river would have broken out of its existing channel decades ago if not held in a straightjacket by the Corps. Lt General Van Antwerp was candid. "We are having to rethink everything. But even if we get it right, and that is no means certain, there has to be the political will to vote the money - and that is beyond my brief."

If the Corps gets it wrong, or the vast sums of money required are not provided, then the Gulf will move inland and eventually the river will break out. Where will New Orleans and the oil industry be then?