Experts say the best protection for New Orleans would include major improvements in five areas. “New Orleans has long lived with the hurricane protection that it, and the nation, were willing to pay for. Measured against the costs of Katrina’s fury, however, better armor may suddenly seem more affordable.

With officials vowing to rebuild New Orleans, the question of how fully to defend the city against another catastrophe will be examined as never before.

Unlike San Francisco or Los Angeles, where there is no way to prevent widespread destruction from the most powerful earthquakes, New Orleans is uniquely dependent on one feature: its aging network of levees. If levees hold back the water, the city is spared. If they fail, much of the city is ruined.

…The success of levees in a restored New Orleans will depend partly on the resilience of other civil engineering, and on wetlands between the city and the Gulf of Mexico. Today, the condition of these outer defenses is poor: Barrier islands and wetlands are disappearing, and gates to protect against storm surges and waves are years away.” (New York Times )