You start by maintaining and policing your levees everyday as if your life depended on it. Read the story of Hans Brinker.
Actually you start by having adequate designs first. The ACOE has stated that the design was flawed. The flood walls were doomed from the beginning.
http://www.boston.com/news/nation/articles/2005/10/26/investigators_posit_levee_design_flaws?mode=PF