For Those Rebuilding in New Orleans, How High?

New Orleans native Al Petrie is trying to take no chances with his new home, right. Post-Katrina floodwaters reached near the top of the front door of his neighbor's home. "I'll be dry," he said. (By Peter Whoriskey -- The Washington Post)

Although lax in comparison, however, the FEMA guidelines are not without their logic.

The guidelines are meant to prevent the flooding of a property in the event of a "100-year storm," or a storm so severe it has only a 1 percent annual chance of happening.

Exactly what the "100-year storm" amounts to for any given location is a scientific question that is complicated enough because accurate storm records can be difficult to come by. But then scientists are asked to estimate what kind of river-level rises and storm surge the imagined storm will generate, and ultimately, how high floodwaters will rise in city streets.

FEMA believes that the required building elevations in place in New Orleans before the storm do not require drastic revisions. But the agency's faith assumes that the levees will hold in a 100-year storm.

The Corps of Engineers is engaged in a $5.7 billion project that they say will bring area levees up to that strength by 2010.

"Katrina was larger than a 100-year storm," said Dan Hitchings, who is leading the Corps repair efforts. And "Katrina was not the largest storm this area could experience."

Of residents' efforts to elevate homes higher than FEMA requirements, Hitchings said, "They are preparing for a storm larger than Katrina, which would be an extremely rare event."

Many in New Orleans are no longer willing to trust in official assurances. They say it's time to heed the example of historic New Orleans, when people built on the higher ground and elevated their homes -- sometimes many feet.

"Our grandparents knew better than to live flat on the ground, but the levees gave people a false sense of security," Petrie, 53, said. "We trusted them before, and look where that got us."