CNN.com: Study finds rapid pre-Katrina sinking in New Orleans Certain parts of New Orleans subsided more rapidly than predicted, i.e. more than one inch per year, over the last four years, contributing to localized levee failure after last year’s Hurricane Katrina.
“What we found is that some of the levee failure in New Orleans were places where subsidence was highest,” University of Miami professor Tim Dixon* said in a news release from the school. “These levees were built over 40 years ago, and in some cases, the ground had subsided a minimum of 3 feet which probably put them lower than their design level.”
Scientists made the measurements by studying more than 100,000 images taken by a Canadian satellite monitoring the wetlands around New Orleans … [they] did not know about the images until after Katrina.
No one predicted levee failure of this magnitude before the storm and assumed they would hold despite increasing subsidence rates. Do these scientists now care to tell us where else levees are at risk, or should we just assume that all New Orleanian canal levees are unfit for human reliance?
… some places, including the Lakeview and Kenner areas, would continue to sink about an inch per year over the next 10 years but that the average would be a fraction of that.
“We need to think long term, think of what will happen in the city in 50 or 100 years,” [study co-author Shimon Wdowinski] said. “Some areas will continue to subside, the sea level will continue to rise. Places like the Lower Ninth Ward will be 10 feet below sea level.”
“Pervasively flawed” levees built on the accelerating subsidence of organic-rich sediment. Crumbling wafers on melting icecream. Hark, what news through yonder window bleats? Why, flood barriers are mostly back to strength, say the Army Corps of Engineers. And what more?
“If another Katrina hit, the levees aren’t magic,” said Col. Lewis Setliff III, commander of Task Force Guardian, the corps team making the repairs. “They are built to a certain height, and if you have a storm surge that exceeds that, you would have overtopping and you would have flooding in traditional low-lying areas in New Orleans. But what we are going to do is prevent the catastrophic failure of these levees and floodwalls.”
You hear that? The levees are not held up by binding spells, but the corps will magically prevent the catastrophic failure of our levees and floodwalls. Recall these words come the end of hurricane season.
*who, incidentally, performs research close to my heart
