We had several ZS members in the path of Katrina. Raptor was in New Orleans and wrote this very thorough description of his experience. This is a must read for anyone who hasn't been through a large scale disaster. It is very eye-opening.
In a similar thread, raptor discusses more generically the effects of being a refugee. It's also a great read. One never knows when they may be forced to evacuate their home. Being mentally prepared is the most important thing you can do ahead of time.