Re: Hurricane Katrina

On Tue, 30 Aug 2005 11:34:34 +0100 (BST), dbell@xxxxxxxxxxxxxxx ("David
G. Bell") wrote:

<interesting stuff>

There is another aspect of the situation reported at:
http://www.msnbc.msn.com/id/9118570/
<quote>
Wetlands erosion raises hurricane risks
Natural storm 'speed bump' around New Orleans now missing

By Bob Sullivan
Technology correspondent
MSNBC

The very technology that protects New Orleans from flooding has
backfired, environmental experts say.

They say the levees that ring the city have led to the rapid decay of
nearby wetlands during the past century, removing a crucial buffer zone
that once protected the area from hurricanes.

Hurricanes quickly lose force when they hit land, but New Orleans is now
vulnerable to violent storms because the land around it has been rapidly
disappearing. Today, New Orleans is almost completely exposed to the
Gulf of Mexico, said Val Marmillion, a consultant for the America's
Wetland group, which is lobbying for the Louisiana coast area.

"There are almost open water conditions around New Orleans now,"
Marmillion said. "Because of wetland loss some areas of Louisiana are no
longer protected at all."

Wetlands act as a "speed bump," slowing down storms almost like dry land
does, said Kip Patrick, spokesman for America's Wetland. "They take some
of the brunt of the force of the hurricane, weakens the storm like any
land mass would."

Sidney Coffee, executive assistant to the governor for coastal
activities, said about 1,900 square miles of wetlands have disappeared
from the area since the 1930s, and the receding continues at a rate of
about 24 square miles per year. The erosion has a direct impact on New
Orleans' ability to absorb the blow of a storm like Katrina, she said.
For every 2.7 miles of wetlands, storm surges are reduced by about one 1
foot, she said.

"We've tried and tried and tried to tell people this is real, this is
happening. This is happening a little bit every day," she said. "But
it's a real emergency."

Area residents can see the effects of decreased wetlands even with large
thunderstorms, she said. Some area highways now flood regularly just
from the day's high tide, she said.

“We've lost so much of (the wetlands), it puts cities at greater and
greater risk," Coffee said.

Several factors — most human-made — have contributed to the steady
decline of the delta at the bottom of the Mississippi. But most of the
erosion is blamed on the levees, which faithfully steer all the water
from the Mississippi into the Gulf of Mexico. That prevents occasional
flooding, keeping area residents above water most of the time. But one
unforeseen consequence of the levees has been to cut off wetlands from
their life force.

The regular floods served nature's purpose by feeding the delta,
bringing fresh water and sediment that served to sustain life and
replenish the wetlands. Without the regular flooding, the wetlands
naturally “compact.”

“Simply put, when the land does not have any nutrients and fresh water
it dies,” Marmillion said.

Fixing the problem will be costly and time consuming.
....
</quote>
--
Peter Duncanson
UK (posting from ukba)
.

Relevant Pages

  • Re: Written September 2002
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