Vegetative Based Solution to Controlling Overbank Scour in the Mississippi River Floodplain Mississippi County, Southeast, Missouri

Thompson Bend is located on the right descending bank of the Mississippi River between river miles 30.0 and 4.5 above the confluence of the Mississippi and Ohio Rivers. The river flows in a broad sweeping reverse curve in this reach, and encompasses approximately 10,000 acres of valuable agricultural land. At the throat of the bend, the overland distance is approximately one mile. The distance along the thalweg is approximately 1.4 miles. During flood events, the river naturally tries to take the shortest path, straight across Thompson Bend. The normal slope along the thalweg is 7 feet, or about 0.5 feet/mile. When flows cross the bend, the 7 foot drop occurs across approximately 2 miles, producing a slope approaching 3.5 feet/mile, depending on the Cairo gage. This paper will discuss in detail how this situation developed, what attempts have been made to control it; how it was severely tested in the Great Flood of 1993, and the floods since 1993. It will Illustrate that overbank scour can be controlled by vegetative efforts and well designed tree screens, and in conjunction with planting certain types of crops at key locations, can almost entirely eliminate surface erosion. It will discuss what is being planned for 1997 to further stabilize the scour and what long term goals are expected.