Feb 09, 2018

Mississippi River Could Change Flow in Extreme Flood

A new study suggests that an extreme weather event could send the Mississippi careening down the Atchafalaya River and dry up New Orleans

Mississippi could change course

A new study presented at the American Geophysical Union suggested that it is possible for the Mississippi River to change course from flowing down the lower Mississippi to flowing down the Atchafalaya River into the Gulf of Mexico. The study’s lead author and professor at Louisiana State University, Yi-Jun Xu, analyzed rising riverbeds and sandbars down the lower Mississippi and around the OId River Control Structure in his research. Xu concluded in the event of extreme flooding or hurricanes the Mississippi could overwhelm the control structure and completely change course.

Over the past century, the Mississippi had naturally been changing its flow towards the Atchafalaya channel until the U.S. Army Corps of Engineers (USACE) began regulating the flow in 1959 through a series of dams and levees known now as the Old River Control Structure. If the USACE had not stepped up to manage the flow, areas along the current Mississippi path would have dried up, specifically in New Orleans, and seriously altered both industry growth and drinking water quality, as reported by Baton Rouge, La., news source The Advocate.

According to Xu’s finding, the riverbed downstream of the control structure has risen 30 ft since 1992 and some sandbars have tripled in size due to sediment buildup. He predicted that if the sediment continues to build up and the waterline continues to rise an extreme flood, storm or hurricane could potentially overwhelm the current control structure and completely change the course of the Mississippi River to flow primarily down the Atchafalaya River. For residents of New Orleans and Baton Rouge, this could alter the quality of their drinking water rendering it too salty to drink when salt water from the Gulf of Mexico moves upriver.