Mississippi River Cutoffs

Natural and artificial cutoffs on the Lower Mississippi River in the 50-mile stretch north of Vicksburg, Miss., are described with respect to their effect on river shortening and flood-stage lowering. Historical and physical facts are given which explain why, during the period from 1884 to 1932, natural cutoffs were dreaded and engineering measures were taken to prevent their occurrence, thus permitting the river to become considerably lengthened. The paper describes the unforeseen circumstances which caused a cutoff at Yucatan Bend to occur unexpectedly during the low-water season of 1929; and it relates how the satisfactory, manner in which the cutoff developed unassisted gave impetus to the launching of a program of river shortening by artificial cutoffs, the first of which, across Diamond Point, was opened on January 8, 1933. The technique adopted avoided making cutoffs across narrow necks, except where conditions made this necessary, and also avoided the pitfalls of European practice. Since that date fourteen additional cutoffs have been constructed, making a total of sixteen. In connection with other forms of channel rectification and dredging operations, these cutoffs have shortened the Lower Mississippi a total of 170 miles between Memphis, Tenn., and Baton Rouge, La., in an original 680-mile river length, or 25%. The appreciable lowering of flood stages which resulted from the cutoffs has saved vast outlays in levee construction. The cutoff data presented are from the records of the Mississippi River Commission.