What's going on in Louisiana - pretty much a logistical nightmare actually.
The storm and subsequent flooding have reduced access to the city down to one or two major roads. Most of the boats are toast and navigable waterways are no longer navigable because they're clogged with debris (cars, shipping containers, damaged vessels, chunks of buildings...) The airports are also submerged. So basically there are very few options for getting stuff into or getting stuff out of the city.
The breaches in the levees are immense and they haven't figured out yet how to drop enough stuff in there to plug them. The Corps (who have a lot of experience in stopping up vast volumes of water - particularly along the Mississippi) has been dropping their biggest sand bags into the breaches for a couple of days - not working. They'd love to drop a few barges in to plug up the holes but they can't get them there due to the aforementioned crap clogging up the waterways.
There is much more. Go read it all.