If this event is to be properly evaluated, countless lessons learned need to be applied. No question the local governments failed ... thousands are dead. NO was not destroyed by a natural disaster. It was destroyed through improper management and supervision. AT ALL LEVELS. The District Commander of the Army Corps of Engineers has many questions to answer on why he should not be Relieved for Cause and Courts Martialed. After the emergency was declared by the President on Saturday, what actions did he take? He KNEW the levees would not hold. What assets were sent to the city on Sunday to help save the city? What "Warning Orders" to which engineer units were issued SATURDAY? If none were issued, WHY? The President declared an Emergency. After the levee was breached, REPAIRS STOPPED at night. WHY?
Save the city? Those levees weren't meant for a Category 4 storm. The part of the levee that broke was an area that had been fixed. When a hurricane of that magnitude is coming, it's too late to start repairing anything. It's time to run for cover. Evacuate. Load up the buses and get the hell out.
No levee can hold. Any earth levee will only buy you time. When the water table is signivicantly higher on one side than on the other, the water will immediately begin seeping through the ground to the lower side. It is only a matter of time before there is a blowout and the water will start gushing, then eroding a larger hole, then the whole thing collapses. The only way to hold back the water is a perfectly impermeable barrier that goes all the way down to bedrock. Even that may not work for long depending on how porous the bedrock is and how well anchored the barrier is to the bedrock. And you and I as tax payers would never agree to such an expense.
I don't know what efforts were made to shore up the levee before the breach, but once a levee is breached, the water on both sides WILL equalize. Continued shoring efforts may help a tiny bit, but would be about as effective as trying to battle a blaze in a 1920's film vault.