Saturday, May 14, 2011
Another Disaster for New Orleans?
We hope not!
Many have inquired of Queen G what will happen to her beloved New Orleans. Barring an unexpected levee breach, probably nothing. Thanks to years and years of efforts by the Army Corps of Engineers, New Orleans and Baton Rouge are well-protected by an ingenious and time-tested system of levees, spillways, and reservoirs designed to divert water through less populated areas to protect the big cities from disaster. In fact, the effort is so important to trade and commerce in the US that the Corp has special "Team New Orleans" to manage the intricate levee and watershed system.
Much of the devastation caused by Hurricane Katrina was due to a levee breach, but that situation was very different. Levees are designed to hold water "in". The berm is designed to withstand the lateral force of the river pushing against it. The storm surge from Katrina placed force on the levees from outside. With equally strong forces from both sides at some points, the levees basically washed away, leaving gaping holes that spilled water into New Orleans. The levee isn't designed as a seawall, although lessons learned from Katrina have helped the Corps location potential weak points, where they have redesigned the levees to be less susceptible to such a situation.
Along the levee systems are interchanges called "spillways", that divert water from the river into large areas of primarily swampland, where it can flow into the Gulf through the marshes. If you've ever driven along Interstate 10 between New Orleans and Lafayette, you crossed these reservoirs on long, long bridges. Just west of New Orleans, the Bonnet Carre spillway has already been opened, and you can see the water rushing under the bridge as you cross. The image above shows the inundation of swampland with the Bonnet Carre opened, plus the risk to New Orleans and Baton Rouge if something else is not done. The Bonner Carre is always the first spillway opened, as the land that it floods is virtually all swamp, and the only humans affected are the relatively small population of trappers and fishermen who make their living in the those swamps.
The more controversial relief is the Morganza Spillway, indicated in this image.
This image shows the inundation of swamp land if the Morganza Spillway is opened 50%. New Orleans and Baton Rouge are completely spared, as most of the flooding is diverted into swampland. However, the controversy comes from the fact that there are more people and towns in the path of the Morganza Spillway, including Morgan City and Houma.
The Morganza has not been opened since 1973, so it really is an action of last resort. Estimates are that 25,000 people would have to be evacuated to save their lives if the spillway is opened, and there property will almost certainly be lost.
As of Saturday morning, the Corps has begun opening the Morganza Spillway. Queen G would certainly hate to be the person who has to make the decision to displace 25,000 peope from their homes and livelihood. Still, it's a numbers game, and by predictably evacuating this smaller number of people, we may prevent a disaster that would affect over a million people.
So, New Orleans and Baton Rouge should be okay- thanks for asking!! And please keep the people of Houma and Morgan City in your thoughts, and consider donating what you can to the American Red Cross. Out Cajun freres and soeurs need our love and support!