Healing Katrina's Damage to 'Liquid Louisiana' (National Public Radio)

Morning Edition, September 23, 2005 · The geography of southeastern Louisiana is unlike any place else on Earth. Much of what looks like solid ground on a map is actually marshland, floating like a pancake on a plateful of syrup.

Scientists are now piecing together how Hurricane Katrina affected those marshes, which form a buffer against storms and flooding. What they find will help determine how the region is rebuilt. For the latest NPR/National Geographic Radio Expedition report, Christopher Joyce journeys to "liquid Louisiana" to survey the damage.

Scientists believe Hurricane Katrina created a giant storm surge that gathered in the Gulf of Mexico and barreled westward up the wide swampy delta on its way to New Orleans. It may have reached 20 feet high by the time it hit the city's eastern suburbs.

Levees built to protect the city may have actually focused that storm surge: Instead of spreading a sheet of water out across the delta, the levees created a channel for the surge. Also, the natural marsh buffer zones that soften the blow of a storm surge have been largely replaced or hemmed in by ship channels and development. All those channels and levees cut off river sediment that enable the marsh to take root and thrive.

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