Hurricane Katrina was serious indeed. Since the City of New Orleans is 12 feet underwater already it has always been at risk. The storm surge from Hurricane Katrina went right over the barrier islands and the waves severely impacted the lake. It was also due to the massive rains that filled up the canal over flows and sent increased water up the canals. Meanwhile the Mississippi is on the high side and is now draining in its normal flow plus that of the Hurricane.
Add this to the wind of the Category 4 or 5 Land fall of Katrina and it was almost the worst case scenario and the levees were breached in several places and perhaps large enough breaches to actually fill up New Orleans like a bowl of soup. Some computer models have predicted up to 30 feet of water in some places. Not good, obviously and unfortunately those models turned out to be very close to what has now happened.
Even after Hurricane Katrina passed we know it will be three weeks as all the water from the remnants of Katrina runoff down the rivers including the mighty Mississippi which drains as it passes through the City of New Orleans, if and when the banks flow over into the city, the water will continue to flow and getting that much water out of the City Soup Bowl of New Orleans could take months.
It appears that has now happened the city soup bowl is nearly full. But alas from the lake side not the Mississippi side. This has caused complete devastation of the city to the point of some starting to float the question; why bother rebuilding it due to costs? We have been promised we will rebuild and so we shall. That is going to take years. Think on this.