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Katrina update

It was a busy Katrina new update day so I thought I'd bring everyone up to speed. First, NOAA anounced that they are officially reviewing Katrina's status at landfall. As previously reported here, there is growing evidence that Katrina was only a Category 3 hurricane at landfall. This does not predict good things for New Orleans, as it just solidifies the fact that the city suffered far from a 'worst case scenario.'

It seems that the damage from this year's hurricane may not have been limited to property damage. Recent satellite observations indicated that Louisiana marshland was decimated.

From the Associated Press:

In the space of one month, Hurricanes Katrina and Rita tore up about as much marsh in southeastern Louisiana as scientists had previously predicted would be lost over the next 50 years, federal geologists said Wednesday.

Satellite imagery shows that about 60 square miles of marsh were ripped up and submerged around New Orleans, said John Barras of the U.S. Geological Survey. The new findings were presented at a meeting here to discuss the damage the hurricanes did to the coast.


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Of course, this same storm surge that destroyed the marshland was also aided by man-made canals. These canals focused storm surge much further inland and amplified its effect.

From NewScientist.com:

A short cut for shipping into New Orleans acted as a "storm surge superhighway", funnelling water into the city when hurricane Katrina struck.

Hundreds of metres wide and 11 metres deep, the Mississippi River Gulf Outlet (see Map) was built to save ships more than 60 kilometres' travel along the winding Mississippi.

As Katrina crossed the Gulf of Mexico in August, Hassan Mashriqui of Louisiana State University in Baton Rouge ran simulations showing that the MRGO would funnel storm surges from the Gulf and Lake Borgne into New Orleans. He predicted that a surge of 2 to 3 metres per second would breach the walls of the Industrial Canal, which joins with the MRGO, and flood low-lying areas.

These predictions were correct, says Paul Kemp, also of Louisiana State University, who has now modelled the Katrina storm surge. The MRGO suffered the highest storm surges in Louisiana before giving way. That failure led to the flooding of the city's St Bernard Parish.



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Of course, maybe if the levees in New Orleans were built properly this would not have been an issue. A new report found that flaws in construction played as much of a role as the surge itself in contributing to the flooding.

From Bloomberg.com:

Nov. 2 (Bloomberg) -- Flooding in New Orleans after Hurricane Katrina was twice as bad as expected because levees protecting the city were poorly built, a preliminary study of the storm's aftermath has found.

The study, conducted by the American Society of Civil Engineers and scientists from the University of California at Berkley, concluded that levees were often built in unstable sand, incorrectly connected to adjoining levees and not built to withstand the affects of high water levels.

``Many of the widespread failures throughout the levee system were not solely the result of Mother Nature,'' Senator Susan Collins, a Maine Republican, said today at a congressional hearing on the study's results. ``Rather, they were the result of human error in the form of design and construction flaws.''


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Posted by Bryan Woods | Permalink