The map of Louisiana will have to be redrawn. A report on the state’s storm-ravaged coastline published by the National Academy of Sciences last week concludes that there is little prospect of restoring many parts of it. The options “may have to include managed retreat”, leaving coast and marshland to the sea.
The wetlands surrounding New Orleans have been vanishing under water for decades. Hemming in the Mississippi river with levees means that sediment carried by the flow is not deposited on the flood plain, leaving coastal erosion and subsidence to do their worst.
Last year, the academy reviewed the latest coastal protection plans, which the federal Office of Management and Budget had insisted be scaled down to five projects. The academy concluded that four projects to restore wetlands would have only a limited impact. It gave an outright thumbs down to a fifth plan to armour the banks of the Mississippi River Gulf Outlet, the controversial man-made navigation channel that probably made New Orleans flooding worse (91av, 5 November, p 5).
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Even if the original $14 billion plan had been implemented in its entirety, the measures would not have saved New Orleans, says panel member Joe Kelley of the University of Maine. Wetlands are really helpful in limiting the impact of less severe storms, he says, “but a category 5 storm will overwhelm them”.
