Being trapped in an attic is a nightmare. You must consider that when the water rises you can go to the attic but then you most go to the roof to survive. The problem is that you have to break through the roof and in New Orleans the roofs are made of slate.
On one of the shows, I heard them talking about some of the bodies found in Mississippi; they have claw marks on their hands and their feet where they obviously had been trying to break through their roofs.