This is lifted from a larger map, probably from the Times-Picayune, that speculated what would have happened if Hurricane Georges had hit New Orleans in 1998. Katrina is a far more dangerous, powerful storm, bringing a larger storm surge. Here’s some details from that map:
Now check out New Orleans proper. The part of the city most people think of, the French Quarter is not actually below sea level. Midcity’s in bad shape though.
It’s Metairie & Kenner that is built on reclaimed marshland that has subsided over the years. A lot of the houses out there have to have pilings to shore them up, as they are quickly sinking into the ground. This is the part of Greater New Orleans that is under the greatest threat.
Of course, with all of the talk about a thirty foot high wall of water coming at shore at the same time of high tide tomorrow, qubbling over what part of New Orleans is really below sea level is a moot point.