Move Mouth Of Mississippi 'To Save New Orleans'

Engineers have said that part of the Mississippi delta must be left to deteriorate completely if New Orleans is to be saved from another powerful hurricane.

Thousands of miles of wetland between the city and the Gulf of Mexico, which once provided a natural buffer to surges created by storms, have been damaged by levees and navigation channels, Scientific American says.

An article in the magazine states that the levees, built by the US Army Corps of Engineers, have prevented flooding to farms, industry and towns along the lower Mississippi River.

But they have also stopped vital silt and freshwater needed by plants, which formed a natural barrier to storm surges, from thriving in the wetland in the 40 miles between New Orleans and the gulf.

The magazine states: "Unless the rapidly disappearing wetlands are made healthy again, restoring the natural defence, New Orleans will soon lay naked against the sea.

"Let the badly failing wetlands there completely wither away, becoming open water, so that the upper parts of the delta closer to the city can be saved."

Three international engineering and design teams that won the Changing Course Design Competition have said the mouth of the Mississippi River, known as the bird's foot because of its shape, must be left to die.

The competition called for an alternative to the Louisiana Comprehensive Master Plan, which would see half of the river's sediment tapped for diversions to try and restore as much of the delta as possible.

The teams revealed detailed plans for the delta on 20 August, stating that there was not enough sediment to rebuild the entire delta and that it would be better to end the river miles north of its current mouth to save the wetlands.

This would be achieved by putting gates in the levees to allow the sediment and freshwater into marsh areas.

One of the teams said saving the wetland area, and subsequently New Orleans, could cost up to $5.7bn.

At least 1,833 people died when Hurricane Katrina caused a large storm surge to flood New Orleans and swathes of the Gulf coast in August 2005.

The levee system was widely accepted to have catastrophically failed, and the responsibility for the flooding was placed on the US Army Corps.