I propose digging a vast reservoir somewhere away from the city, in one of those barren rural areas nobody cares about. This is the US, we have plenty of those. Dig the largest reservoir the world has ever seen, larger than the second largest by an order of magnitude, thereby enlarging our national "infrastructure" by a similar degree. Think of all the new jobs! Connect this reservoir to n'orleans via underground aqueducts. Flood water will drain through the aqueducts and out of the city. This underground system, powered by the laws of physics, would be immune to hurricane and flood damage as long as the reservoir functions.
Now, the obvious problem is reservoir capacity. Luckily, the reservoir is out in the middle of nowhere, allowing us to build huge water holding tanks, pumps, and so forth to empty it out. This system will be outside the hurricane/flood zones, and since it isn't within a populated area it can be much more robust than a city pump system. Furthermore, an array of voodoo priests and druids from n'orleans will periodically bless the reservoir with charms and wards to protect it. The natural power of hundreds of voodoo rituals will guarantee the system's smooth function during crises. In addition, some of these voodoo rituals require large amounts of energy to complete, so we'll have to have massive orgies on the site to reinforce the system. Who could argue with that?
Entrance fees to the ritual orgy will cover a large portion of the costs of the project, and the remaining funding can be gathered by using it as a Sea World. It would be the largest man-made aquarium in the world! Think of the tourism potential. (cue the slashdot trolls with that dolphin link)
It's a brilliant plan. Protection from floods, protection from droughts, new tourism revenue, jobs, hot sex, awesome voodoo powers, and enlargement of the national "infrastructure." What more could you ask for? That's pure New Orleans, baby.