for National Geographic News
New Orleans is surrounded by waterLake Pontchartrain, the Mississippi River, and the nearby Gulf of Mexico. Resting an average of six feet (two meters) below sea level, the city's safety has long depended on one of the world's most extensive levee systems.
On Thursday afternoon, U.S. Army Corps of Engineers officials briefed reporters on the status of that levee system, even as much of the city remained flooded and crews worked to repair breeches along city canals.
The bowl-like shape of New Orleans prevents water from draining away, as broken levees continue to allow water to flow into city streets. No one is sure how long it will take to pump out floodwaters once the levees are repaired.
Lt. Gen. Carl Strock, chief of engineers for the Corps, dismissed suggestions that recent federal funding decreases or delayed contracts had any impact on levee performance in the face of Katrina's overwhelming force.
Instead he pointed to a danger that many public officials had warned about for years: The system was never designed to withstand a storm of Katrina's strength.
"It was fully recognized by officials that we had Category Three [hurricane] level of protection," Strock said. "As projections of Category Four and Five were made, [officials] began plans to evacuate the city.
"We were just caught by a storm whose intensity exceeded the protection that we had in place."
What Price Protection?
The U.S. Army Corps of Engineers has been building levees along the Mississippi River since the late 1800s. The artificial, reenforced soil embankments are designed to curb periodic and destructive floods.
But determining the level of protection needed versus what Congress and the public are willing to pay for isn't often easy.
Acceptable risks must be weighed, including the statistical likelihood of catastrophic events and the possible consequences if they do occur, according to U.S. Army Corps of Engineers officials.
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