re: Escalating Floods Putting Mississippi River’s Old River Control Structure at Risk

Above: Aerial view of the four structures of the Mississippi River Old River Control Structure, looking downstream to the south. Water flows from the Mississippi River through the four structures, to the Atchafalaya River (right). Image credit: U.S. Army Corps of Engineers.


Figure 1. Louisiana as seen by the MODIS instrument on March 21, 2019, showing the location of the Mississippi and Atchafalaya rivers, plus the Old River Control Structure, which diverts 30% of the flow of the Mississippi into the Atchafalaya. Floods of the two rivers were creating large sediment plumes in the Gulf of Mexico. Image credit NASA.


Figure 5. The Old River Control Structure’s Low Sill Structure as seen in April 1973. Turbulence from a major flood caused the 67-foot long southern wing wall on the intake channel leading to the Mississippi River to collapse on April 14, and a large eddy can be seen where the wall used to be. The eddy helped scour out a football field-sized hole up to 50 feet deep that undermined 7 of the structure’s 11 gates and nearly caused its failure. A ramp leading to the eddy was built, and an emergency stone replacement dike was built. Image credit: USACE.