Sedimentation, navigation, and agriculture on the lower Missouri River

Abstract

T he Missouri River arises from the eastern slope meltwaters of the Rocky Mountains in the northwestern United States. As it flows across the Great Plains to its confluence with the Mississippi River at St. Louis, Missouri, it accumulates a large sediment load earning it the name “Big Muddy.” The natural gravity of water is powerful, capable of carving rocks and eroding soils to create new channels and deepen existing ones via the continuous sediment transport and deposition processes. Rates of upland and river bank sediment erosion, deposition, and transport are influenced by upstream geology, topography, vegetation, and land uses; variations in climate and weather; and the river flow structure and channel morphology (Nazari-Giglou et al. 2016; Coleman and Smart 2011). The headwaters of the Missouri River and it major tributaries, the North and South Platte rivers and the Yellowstone (figure 1), are fast moving, and they cut narrow, deep channels as they rush down steep mountain slopes. However, the waters slow as they flow into the Great Plains and spread out into broad, shallow, braided streams that redistribute sands and silts and create sandbars, wetland backwaters, and new pathways (figure 2). River sedimentation is the result of natural and anthropogenic…