Floodflow characteristics of Mulberry River at Interstate Highway 40, near Mulberry, Arkansas

The flood on December 9-10, 1971, at Mulberry, Ark., damaged the west spur dike of the Mulberry River bridge. In addition, there was considerable scour around the toe of the dike and around some bridge piers and a moderate amount of filling under the west end of the dual structures. The Arkansas State Highway Department requested a study of the flow characteristics of the December 1971 flood. The peak flow was 56,100 cubic feet per second (1,589 cubic metres per second) and was analyzed for three conditions: (1) with dike shortened, (2) with dike repaired, and (3) with a relief bridge west of the main bridge. The flood of 56,100 cubic feet per second (1,589 cubic metres per second) would not cause serious damage with the dike shortened and riprapped. Repairing the dike to the original dimensions would not solve the problem. A relief bridge would eliminate the extreme concentration of flow near the dike and would reduce the mean velocity and backwater in the main bridge section.