Old River Control Structure

from Wikipedia, the free encyclopedia
Old River Control Structure, looking east-southeast, downstream with the Mississippi River. The three dams on the arms of the Atchafalaya River are in the picture on the right. Concordia Parish , Louisiana is in the foreground on the right side of the Mississippi River, while Wilkinson County, Mississippi can be seen in the background on the left bank of the river.

Old River Control Structure is a system of three weirs with flood flaps on the western bank of the Mississippi River in northern Louisiana at River Mile  315, i.e. 507 km above the Head of Passes (there the main arm of the river divides into three estuary arms, which are divided into drain the Gulf of Mexico ). The structure complex is located at the point where the Atchafalaya River , an estuary of the Mississippi River, separates from the main arm. Completed in 1963, the facility was built by the US Army Corps of Engineers to regulate the amount of water that can drain from the Mississippi River into the Atchafalaya River. If these structures were not there, far more water would flow into the system of the Atchafalaya River, because this course of the river to the Gulf of Mexico is much shorter and therefore steeper than the main arm of the Mississippi River. Usually the water distribution is kept so that 70 percent of the water volume remains in the main arm and 30 percent can flow into the Atchafalaya River.

purpose

The Old River Control Structure is necessary in order to prevent the Atchafalaya River from tapping the water of the Mississippi River main arm, so it comes to a river shift. In such a case, most of the river's water would flow through the Atchafalaya Basin and Atchafalaya Rivers , and the current main arm through Baton Rouge and New Orleans would receive far less water. Some scientists believe that natural processes increase the likelihood of such an event year on year, despite flood control construction . The reasons include the length of the flow path, which is 507 km long via Baton Rouge and New Orleans to the Head of Passes, but only 228 km, i.e. a much steeper gradient, over the Atchafalaya River.

Consequences of a collapse

If either the Old River Control Structure or the structures on Morganza Spillway failed, the consequences for the state of Louisiana , the region and the entire country, as well as international trade, would be immense. The main channel of the river would likely shift into the Old River, Atchafalaya River and Atchafalaya Basin, past Baton Rouge and New Orleans. The existing seaports would have to be relocated, Morgan City and many other smaller settlements relocated. Traffic by road, rail and inland shipping would also be affected. The changing patterns of sedimentation and erosion would lead to the creation of new river beds and the floodplains would also shift. Changes in the salinity of the coastal waters near the previous and new estuary delta would have effects on fauna and flora in the area, fishing , beaches , marshland , coastline and infrastructure .

Flood disasters in 1973 and 2011

The building complex was damaged in the 1973 flood disaster. During the Mississippi flood in 2011 , the US Army Corps of Engineers opened the nearby Morganza Spillway to reduce some of the water pressure on various levees and other flood control structures, including the Old River Control Structure.

supporting documents

  1. ^ McPhee, John: The Control of Nature , 1st Edition, Farrar, Straus and Giroux, August 1989, ISBN 0-374-12890-1 , p. 272.
  2. ^ Angert, Joe and Isaac: Old River Control ( English ) In: The Mighty Mississippi River . Archived from the original on May 15, 2009. Retrieved May 11, 2011.
  3. ↑ a b c Controlling the Mighty Mississippi's path to the sea ( English ) America's Wetland Resource Center. Retrieved May 12, 2011.
  4. ↑ a b Mississippi Rising: Apocalypse Now? ( English ) Daily Impact. April 28, 2011. Retrieved May 12, 2011.
  5. ↑ Will the Mississippi River change its course in 2011 to the red line? ( English ) mapping support. Retrieved May 12, 2011.
  6. ^ Ronald Joel Daniels: On Risk and Disaster: Lessons from Hurricane Katrina ( English ). University of Pennsylvania Press, 2006, p. 45.
  7. ↑ Mark Schliefstein: Record high river likely to require opening of Morganza Spillway next week ( English ) The Times-Picayune (New Orleans). May 9, 2011. Retrieved May 12, 2011.
  8. ↑ Mark Schliefstein: Morganza Spillway might be opened to ease swollen Mississippi River ( English ) The Times-Picayune (New Orleans). May 8, 2011. Retrieved May 12, 2011.

Web links

Commons : Old River Control Structure  - collection of images, videos, and audio files

Coordinates: 31 ° 4 ′ 36.5 "  N , 91 ° 35 ′ 52.4"  W.