Amazing that nobody has pointed out that not only is New Orleans below sea level, it got that way because it is sinking.
It's not an easy thing to fix, and back in the day the people who founded New Orleans didn't say, hey, let's move to a spot that's below sea level, it'll be so cool. We'll have the girls flash their tits to keep our minds off the looming hurricane danger.
The point I'm making is that the city has drastically changed over the last 150 years. If you filled up all of the french quarter with 50 feet of dirt and built on top of it, you would still have the erosion problem and eventually would be back below sea level. That solution has been tossed around for the last 50 years at least, but it's generally accepted that the idea won't work.
The city is doomed, and if you don't want to move the culture then I guess you'll have to accept that you will lose it.