Katrina was the biggest test of the 350 miles of levees and floodwalls that the Corps built and refurbished over the past 40 years--and the system crashed, buckling under 50 major breaks and spilling millions of gallons of water into the city. And Katrina was far from a worst-case scenario.UPDATE: Nathanael of the always insightful Rhine River blog asks:
The Corps' post-mortem of Katrina tells the story: "the system did not perform as a system," its engineers concluded. "The hurricane protection in New Orleans ... was a system in name only.... The majority, approximately two-thirds by volume, of the flooding and half of the economic losses can be attributed to water flowing through breaches in floodwalls and levees." The failures weren't due to construction malfeasance or incompetence: "the system was built as designed," the Corps concluded. But the system was, in many ways, conceived to fail. In the Corps' view, it was inconsistently designed and lacked redundancy--that is, back-up protections.
Some levees, in particular the massive earthen fortresses with wide foundations, performed well, withstanding days of water pressure with little erosion. But floodwalls designed as narrow vertical walls driven into the ground--they look like the walls built on highways to block out the noise--performed abysmally.
First, some walls had sunk up to three feet lower than their original "authorized heights" before the storm. Second, the pressure of Katrina's waters wore away the walls' narrow vertical foundations because they weren't "armored" with erosion-proof material, causing the structures to topple into the water. And because the system wasn't redundant, each break caused additional weaknesses.
Why didn't the Corps design a consistent, redundant system? In large part, the reason was foot dragging--or worse--by pols on the state, local, and federal levels. In some cases, political opposition prevented the Corps from seizing land to build sturdier foundations. Plus, Louisiana's local levee boards were lousy stewards. Levee officials were political animals, not engineering experts, and sometimes proved more interested in running ancillary "economic development" projects than working with the Corps to make sure the levees were up to their task. (It's not because New Orleans is poor and black: the levees protect New Orleans's richer, whiter suburbs too.) In addition, the Corps warned that many of New Orleans's manmade canals, obsolete for years, should be closed or at least gated--to no avail. Moreover, when the Corps, along with state officials, came to understand that wetlands restoration is a vital part of the flood protection system, not a tree-hugger's afterthought, Congress balked at spending the required $14 billion over several decades for coastal restoration....
President Bush's recent rhetoric thus doesn't help New Orleans or the nation. He still talks as if poverty, and not inadequate design and investment in the plain, old, boring infrastructure that makes all cities work, was responsible for Katrina's tragic devastation.
One question scholars have yet to answer: why can't cities, as they did in the past, undertake the grand construction projects of this type? Is there something about the nature of the challenge, be it financial, legal, engineering, ..., that not only makes the federal government better at these projects, but the only actor that can undertake them?To shed a bit of light on this question, here's a quote from John M. Barry's Rising Tide, which I've been reading and excerpting:
For decades the increasingly populated states of the Mississippi valley had been demanding that the national government address navigation and flood problems on the Mississippi River. Conventions in Cincinnati in 1842, in Memphis in 1844, in Chicago in 1847 (where 16,000 delegates overwhelmed a city of 10,000) had pressured Washington to act. At last, to keep the West, the upper Mississippi valley, from forging a political alliance with the South and spurred on by a flood in 1849 that inundated much of the lower Mississippi valley—including New Orleans itself—eastern politicians acceded to the demands, and Congress ceded millions of acres of federally owned "swamp and overflowed lands" to the states. (Footnote: Louisiana received 9.5 million acres, Arkansas 7.7 million, Missouri 3.4 million, and Mississippi 3.3 million.) The states were to sell the land and spend the proceeds on flood control.When states fall down on the job, as they did in 1927 (and 2005), the Feds are the saviors of last resort. (In failed states, international institutions are the saviors of last resort.)