For New Orleans, the brand new federal flood protection held back Hurricane Isaac’s storm surge.
Meanwhile, the Army Corps of Engineers has announced that it will run computer models to determine whether the new system of stronger levees, new gates and structures may have exacerbated flooding in areas outside the system.
Isaac was a more unusual storm. We don’t recall a recent storm coming from the direction that Isaac did. The wind over Lake Pontchartrain was going the opposite direction than Katrina which causes water to surge west of the city. This creates a different flooding pattern. While it does not look like the new higher structure came into play, it is possible. This is a complex issue and modelers need to obtain actual surge height numbers to answer the question of whether the new structure contributed to flooding elsewhere.
But clearly for New Orleans, Isaac was a natural event, the sort New Orleans citizens have dealt with dozens of times. There are no “shades of Katrina.” Seven years ago, there was a horrific flood event due to tragic mistakes made by the Army Corps of Engineers. At a savings of $100 million, the Corps decided to drive sheet piles down only 17 ft instead of 45. This was a tragic human mistake which laid waste to the portion of the city with the highest concentration of people, properly and infrastructure.
But this time New Orleans was dealing with Mother Nature, not the Corps’ mistakes.