It shows my lack of NO and LA geography. I didn't realise there were so many factors involved in a NO flood secnario.
Yeah, I just learned today that the weakest link is the levees on the west side of the city/metro, and the most likely first breach is water coming east from the Bonne Carre Spillway that lies between the SW corner of Lake Pontchartrain and the Mississippi River. If you look at a map, that is the area approx. between where I-10 and I-55 connect and the I-310 interchange.