I really don't understand what is so complicated and difficult about getting water and other simple supplies into New Orleans, not tomorrow, but maybe the day before yesterday. As I understand it , they send helicopters in to airlift out selected people and get surprised when others who have no water or other simple supplies get upset at the basic stupidity of that approach.
Step 1; load a large airplane with lots of bottled water, diapers and perhaps Army MREs
Step 2 fly low over the city
Step 3 Drop supplies wherever you see a gathering of people, using a parachute so every pallet of supplies lands reasonably gently.
It is done in Afghanistan, Bangladesh, etc. so should be feasible in the Continental USA surely. After you have ensured people have basic necessities, then do all your Organising and Paperwork and Law Enforcement.