Big Muddy Speaker Series presents:

Presentation by Carrie Elliot

Hosted by Missouri River Relief

The lower part of the Missouri River downstream of Sioux City, Iowa is a 800-mile long engineered navigation channel designed to keep sediment from building up, so routine dredging is usually not needed. However, seasonal floods can sometimes deposit sand in the navigation channel, which can make it difficult for boats and may require dredging or other maintenance.

Scientists do not yet fully understand how sand moves along the river bed during floods which typically happen in the spring to early summer. To learn more, Carrie Elliot and her team conducted 13 detailed sonar surveys of the river bottom along a 2.5-kilometer section near the Eagle Bluffs Conservation area in central Missouri. During this time, the river experienced a high-flow event that peaked at 215,000 cubic feet per second. The surveys showed that the riverbed can change significantly. In some places, the river’s bed rose or dropped by as much as 4 meters, with an average change of about 2 meters. During the high-flow event, the riverbed eroded overall, although some areas also experienced sand buildup. After the flood peak, surveys showed a general trend of sediment slowly building back up in late summer and fall.  Similar trends occur in other sites where repeat measurements have been made.

Understanding how flows and sediment interact on the Lower Missouri River will help to guide future management decisions. Join us as we track the ever-shifting sands of the Missouri River.

This presentation originally took place on Tuesday, September 8th at the Riechmann Indoor Pavilion in Columbia, MO.