How many roads available to bring supplies in and take people out?
Looks like one. On the satellite photo below, I have put symbols on the roads and bridges we know are closed. We also know that Slidell Louisiana at the top of the I-10 bridge is in ruins, the railroads are in ruins, the Intercoastal waterway is closed, the Mississippi River is closed. All water for the helpers has to be flown or trucked in, all food has to be flown or trucked in. Bring in more troops and you add to the logistics problems. Add more helicopters and you add more flight crews and support crews and fuel issues.
The right solution (maybe the only solution) is to clear the city as fast as possible. However, there is a limit on the number of buses available and buses in transit to Houston or San Antonio take at least 12 hours to transit back and forth (and need drivers who need water, food and rest. Because of the distances involved you may need 4 times the buses you would need to move people 100 miles (can't move them that short a distance there's no food, water, shelter, or electricity). And new people keep arriving to be transported. Can't take them by boat, because the river system is closed. Can't take them by air because the air system is closed.
Using self-contained assets (those that bring their own food, shelter and water) is vital. Right now, the best such platform is USS Bataan which is on station and working. Bataan seems to be limited by safe navigation issues to moving no closer than 80-90 miles off New Orleans. More ships will join her soon...
The ships enroute from Norfolk will arrive in a couple of days (note: A CNN newsreader is pounding some expert asking why all the "military" stuff is not already on scene - three days after the disaster- look, Lady, the Navy cannot teleport its ships- they have to sail from Norfolk, down the East Coast, around Florida and across the Gulf of Mexico - and there are already significant forces in place - where do you think the helicopters you are showing on your newscast came from?)
This is a hard problem and a time when experts talk logistics and work that end of the problem.
UPDATE: I have attempted to clean up this post to make my thoughts clearer. Part of what I'm saying is expressed by Austin Bay when he writes:
We’ve a million people dispossessed and they are suffering. Critics grouse that the response to Katrina’s devestation has been abysmally slow. Compared to what? Slow compared to our expectations is the correct answer. Compared to every other nation on the planet, we’re moving at warp speed to address a natural disaster of extraordinary magnitude.
UPDATE 2: . Photo shows one of the problems in moving suppies into New Orleans.