...After massive flooding killed hundreds in St. Bernard Parish, eastern New Orleans and the Lower 9th Ward, there is growing consensus that Katrina's surge was made far worse by the Mississippi River-Gulf Outlet, a 76-mile shortcut between the city and the Gulf of Mexico. And while the shipping industry vows to protect the channel, political momentum appears increasingly in favor of St. Bernard officials who have long warned the waterway must be closed.
Scientists from Louisiana State University's Hurricane Center say the Gulf Outlet, also known as MR-GO, and a second channel, the Intracoastal Waterway, funneled Katrina's powerful surge into a narrow bottleneck just north of Chalmette.
The funnel caused floodwaters to stack up several feet higher than elsewhere in the metro area and sharply increased the surge's speed as it rushed through the MR-GO and into the Industrial Canal. As a result, levees that would have been topped -- but not breached -- crumbled under the hydrologic assault, turning a major flood into an unprecedented disaster, according to Hassan Mashriqui, a civil engineer from LSU who had predicted the funnel effect prior to the storm.
Absent the funnel effect, Mashriqui said, "you would have had maybe 2 to 3 feet of flooding at the max, but not everybody's house underwater. It's still flooding, but one is significant and one is catastrophic."
The Port of New Orleans and Army Corps of Engineers dispute the Hurricane Center's claims, saying Katrina's intensity was enough to topple levees regardless of the shipping channel. Those levees were built to withstand only storms up to Category 3; Katrina made landfall at Buras as a Category 4 storm.
"This was just a ferocious and huge storm," Port of New Orleans CEO Gary LaGrange said.