More Katrina aftermath

This seems to be kind of a big deal:

Experts now believe that Katrina was no stronger than a Category 3 storm when it roared into New Orleans, and Congress had directed the Corps to protect the city from just such a hurricane.

"This was not the Big One -- not even close," said Hassan Mashriqui, a storm surge expert at LSU's Hurricane Center. He said that Katrina would have caused some modest flooding and wind damage regardless, but that human errors turned "a problem into a catastrophe."

...The independent investigations have pointed to two failures in the infrastructure maintained by the Army Corps of Engineers that were critical factors in the destruction Katrina wrought in New Orleans.

In 1965, the Corps completed the 76-mile-long, 36-foot-deep Mississippi River Gulf Outlet, a larger dirt-moving project than the Panama Canal. The outlet -- known locally as MRGO, or "Mr. Go" -- created a navigation shortcut to the Port of New Orleans, although a little-used one that averages fewer than one ship a day. But the outlet also amounted to a funnel that would accelerate and enlarge any storm surges headed for the city's levees.

Three months before Katrina, Mashriqui told a room full of emergency managers that the outlet was a "critical and fundamental flaw" in the Corps' hurricane defenses, a "Trojan Horse" that could amplify storm surges 20 to 40 percent.

With the help of a supercomputer, Mashriqui has now concluded that the effect was even worse than he predicted.

The analysis shows that the outlet's "funnel" intensified the initial surge by 20 percent, raising the wall of water about three feet. But it also increased the velocity of the surge, which Mashriqui believes contributed to the scouring that undermined the levees and floodwalls along the outlet and Industrial Canal. He found that Katrina's surge moved through nearby Lake Borgne at less than 3 feet per second. But the rate was about 6 feet per second at the mouth of the funnel, and as much as 8 feet per second in the funnel.

Blame...LBJ?