I have a hard time believing that a city in an ancient civilization would have coped anything like that well with a similar disaster (think Angkor for example). This is quick bit of lunchtime research inspired by this Open Mind post - New Orleans seems like a prototype for worst case scenarios for cities that experience failures in their response to 21st century sea level rise.
I stress I'm not trying to minimize the enormous suffering of the people of New Orleans - just pointing out that the city is still there and has a functioning economy that is only slightly smaller than before the disaster. New Orleans is clearly not going to end up as ruins in the bayou as a result of Katrina.
The data are from the BEA.
