Awareness of how to prevent a similar outcome of happening again
People! You need to realize that when someone says that there is a BIG storm com in, YOU NEED TO PREPARE. I read so many stories of people that ignored the warning and weren't prepared for the storm. You need to evacuate and save your life!
Failure of Levees
The reason why 80% of New Orleans flooded was because of levee failure. The blame immediately went on the US Army Corps of Engineers. The levees weren't built to suit the amount of water Katrina caused. Overtopping of the levees (the levees were too short), erosion, failure in foundation soils underlying the levees, and seepage through the soils under the levees causing piping failures were the main reasons the levees broke.
How to prevent it
Preventing another disaster like Hurricane Katrina won't be easy. New flood protection systems will have to be put in so they can stand another hurricane if it was to come. That alone will cost around 14.5 billion dollars and cover over 133 miles.
Basic Info of Katrina
Katrina didn't do as much damage to New Orleans as the breaking of the levees. 80% of New Orleans was flooded and caused most of the deaths. The hurricane caused economical chaos, also. Gas prices went through the roof because oil refineries shut down and jobs were scarce. Ports in New Orleans were destroyed which hurt the US's shipping industry. Katrina was a category 3 hurricane at land fall.