Monday, June 05, 2006


Katrina: 4 storms

An Autopsy of Katrina: Four Storms, Not Just One
This is a facinating read from the NYTimes.

The first stage of Hurricane Katrina touched Louisiana as it passed south of the city in the Plaquemines Parish town of Buras with winds of more than 125 miles per hour pushing a storm surge. The wind and water overwhelmed the local hurricane defenses: levees built to withstand 13 feet of water were overwhelmed by more than 17 feet of surge, damaging levees and scattering homes and boats across the thinly populated parish like toys.

As the hurricane moved across Lake Borgne to the east, the effect was quite different: the second storm sent strong waves and a surge estimated at 18 feet or more back across the lake to the levees bordering St. Bernard Parish. The long levees there had been designed to handle 13 feet of water. The assault washed over Chalmette and other communities with floodwaters exceeding 14 feet in some areas. A similar pounding took out the southeastern levee of the development known as New Orleans East.

In its third incarnation, the storm sent the water up a funnel formed at the northwest corner of Lake Borgne and into the city's Inner Harbor Navigation Canal, where the water rose and churned with exceptional force, said Hassan Mashriqui, a researcher with the Louisiana State University Hurricane Center. Those waters shattered flood walls in several places and destroyed the city's Lower Ninth Ward.

As the storm pushed into Mississippi, it sent a final surge toward New Orleans across Lake Pontchartrain, north of the city. As the water stacked up against the south shore of the lake, it rose against the walls of the three main drainage canals that run from the center of the city. Though the surge was weaker than the others and the water did not reach the tops of the flood walls, the 17th Street Canal and the London Avenue Canal suffered breaches that caused the lake's waters to spill into the center of the city.

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