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Floodgates could raise New Orleans rain flood risk

July 27, 2006

By Peter Henderson

NEW ORLEANS (Reuters) – Flood defenses meant to protect New
Orleans from hurricanes could lock rain in the city and put
some areas 5 feet under water during a tropical storm, the U.S.
Army Corps of Engineers said on Wednesday.

The Corps is responsible for rebuilding the city’s shield
against storms after Hurricane Katrina ravaged New Orleans last
August, killing 1,336 on the Gulf Coast, according to the
National Hurricane Center.

The Army released maps on Wednesday showing new floodgates
built to keep out storm surge could disrupt the system for
draining rain from low-lying areas.

That has been a major concern of community groups and
supporters who argued the Corps’ storm barrier plan had a
potentially fatal flaw — not enough pumps.

Most of New Orleans is below sea level and pumps out
rainwater beyond the ring of protective levees.

“Large areas of the metro area that may have had minor
street flooding before will now have 2 to 3 feet (0.7-0.9
metres) on top of that — significant home flooding — because
of the Corps’ failure to build adequate pumping capacity for
this hurricane season,” Louisiana Sen. David Vitter said in a
statement after the Corps released the maps.

“Our whole recovery is at stake,” the Republican lawmaker
said.

The problem stems from the Corps’ decision to close the
entrances to city drainage canals with floodgates, which would
keep out the storm surge that devastated the city during
Katrina, when 80 percent of the city flooded.

But the Corps’ plan also makes it harder to empty low-lying
New Orleans of pooling rainwater, and critics say the Army
needs to speed plans to add more pumps to compensate.

The Corp said the floodgates would be closed only in
extremely rare storms, and that it was adding pumping capacity
month by month.

The maps on the Corps Web site
(http://www.mvn.usace.army.mil/hps/depth_inundation_maps_07_26.h
tm) show a number of sections of town could have more than 5
feet of flooding if 9 inches of rain fell in a six-hour period,
which is possible in a tropical storm.

That would drop to a maximum of 2 to 3 feet flooding in
most of the affected areas as new pumping capacity is added in
September, according to the Corps, which released maps showing
a number of scenarios.


Source: reuters



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