Katrina’s Real Lesson

Though President Bush declared on Saturday that Hurricane Katrina exposed “deep-seated poverty” in America, the disaster isn’t ultimately a story of poverty or of race, but of the greatest failure of civil engineering in American history. Luckily, while the nation has never been able to solve poverty, it can solve the engineering problem at the heart of southern Louisiana’s potential recovery.

First, some history. Like the Netherlands, much of urban and suburban New Orleans is below sea level. New Orleans started building rudimentary levees to protect residents and businesses from flooding in the mid-1700s, after settlers realized that their city’s vital economic asset, its position at the mouth of the Mississippi, was also its greatest liability.

This liability intensified two centuries later, when New Orleans drained low-lying swamps to build neighborhoods right on Lake Pontchartrain, and when erosion, much of it from the digging of canals that allowed for oil and gas development in the Gulf of Mexico, destroyed half of the 2,800 square miles of wetlands that protected the coast, thereby moving the Gulf 20 miles closer to the city. Those miles proved vital, because storms weaken as they pass over land. Man-made shipping canals within New Orleans would also funnel floodwaters into populated areas.

But as the risks facing New Orleans grew more complex, New Orleans’s hurricane protection system—its levees, floodwalls, and natural barriers such as wetlands—didn’t keep up. The Army Corps of Engineers started building today’s hurricane protection system in 1965, after Hurricane Betsy flooded many of the same areas that Katrina inundated 40 years later. (The feds pay for 70 percent of the system, partly because they earn royalties from offshore energy production.)

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.

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.