The Coast Guard Compass is doing a series on Katrina. Its worth a look. These are the posts published so far.
- http://coastguard.dodlive.mil/2015/08/remembering-katrina-the-watch/
- http://coastguard.dodlive.mil/2015/08/katrina-10-years-later/
- http://coastguard.dodlive.mil/2015/08/remembering-katrina-landfall/
Chuck Hill's CG Blog 
Study addresses probability of something similar happening in the future. http://www.fiercehomelandsecurity.com/story/future-coastal-flooding-risks-economic-losses-will-rise-several-major-us-ci/2015-08-31
I you remember what storm surge did to places like Waveland, MS, you really don’t have to have a levee break to have substantial flooding and casualties.