Naw, there are ramps leading to the dome, that could be use as boat launches. It will just take a while. Could also get the military to put in a pontoon bridge to the higher ground several blocks to the west on the river levee, where the convention center and casino can be used as a more comfortable evac. camp. Could also load from there onto large ships to move up to other evac tent cities. But those tent city needs just went from FEMA's 100,000 person estimate to maybe 500,000+. At least the south bank river communities should be able to recover much faster.
I haven't heard anything about the areas south of New Orleans. Is that mostly swampland or towns?