OK, since you're an expert on these things perhaps you can why there is a New Orleans Levee Commission.
The Buses would have only complicated matters and even during a "Mandatory Evacuation" people are still Free to Stay in their homes.
This is an absurd statement. Particularly in light of the fact that Mayor of NO didn't issue a mandatory evacuation until the president urged him and the governor to do so last Sunday. Also, it took them damn near forever to even get all the lanes of traffic headed out of town. You saw the video. An eight lane free with only four in use. Something as simple as that should have been a basic response yet it was slow in coming.
However, if you are really interested in the New Orleans Levee system you may want to consult to following link"
http://www.mvn.usace.army.mil/pao/whoweare/index.asp
Notice how the above web address has a .mil domain name. I wonder how the mayor of New Orleans and his "New Orleans Levee Commission" was able to obtain that address?