Environmental Engineering Reference
In-Depth Information
A report released by the National Academy of Engineering and the
National Research Council concluded that no levee or fl oodwall is big
enough or strong enough to fully protect New Orleans from hurricanes
or other extreme weather events.
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The report recommended relocating
neighborhoods to less fl ood-prone areas of the city or elevating homes
above the 100-year fl ood mark as the best strategies to prevent the type
of water damage caused by Hurricane Katrina.
Modern New Orleans is a city whose early inhabitants ignored the
natural setting that was not favorable for human settlement and built in
a mosquito-infested bowl-shaped swamp squashed between two vast
bodies of water. Much of the city is below sea level, and continual
pumping has caused the ground to subside. Since 1878, the city has sunk
15 feet, one of the highest rates of subsidence in the United States.
Added to this is the loss of the coastal wetlands that serve as a
buffer against hurricane waters. In one day of Katrina, Louisiana lost
15 square miles of wetlands, three-quarters of its annual loss. Coastal
degradation was a problem long before Katrina appeared. After the
Army Corps of Engineers “tamed” the Mississippi in the 1940s, the
wetlands, deprived of the river's sediment, began to sink noticeably
below sea level. Their health further deteriorated as extensive canals
were dug, fi rst to explore for oil and gas and then to pump them out.
Adding insult to injury, a beaver-sized rodent, the nutria, introduced
in the 1930s for its fur, turned out to have a voracious appetite for
marsh plants. More than 1,500 square miles of wetlands have been
lost since 1950.
The long odds against saving the city led geologist Robert Giegengack
to tell policymakers a few months after Katrina hit, “We simply lack the
capacity to protect New Orleans.”
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He agreed with Wilson Shaffer, a
storm-surge modeler at the National Weather Service, who wrote in
1984 that “there are no high areas near the city that wouldn't fl ood in
extreme cases. High ground is several tens of miles away.”
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Giegengack
recommended selling the French Quarter to Disney, moving the port 150
miles upstream, and abandoning the city to the Gulf waters that are
certain to cover it in the not-too-distant future. Others have suggested
rebuilding it as a smaller, safer enclave on higher ground.
The brutal hurricane that hit Galveston, Texas, in 1900 may be a
guide to the future. Most survivors of that deadly storm moved to higher
ground. After the hurricane, Galveston, which had been a large and
thriving port, was essentially abandoned for Houston, transforming that
sleepy backwater into the fi nancial center for the entire Gulf South.
