I have seen many similar comments and people need to understand very clearly:
The water CANNOT RECEDE from the City of New Orleans.
The water must be pumped out. The vast majority of these people will need to be rescued/evacuated long before any sort of reasonable life sustaining services are available.
This is not a 'wait it out and hope for the best' situtation - it is a 'get out as soon as you can anyway you can' situation.
I hope some operation is being planned or underway to get those people out.