Missouri River Slope and Sediment

The project for the improvement of the Missouri River consists primarily of open-channel regulation, which contracts the natural channel in addition to materially changing its shape. A general description of the methods adopted is given, together with a quantitative summary of the effects of the improvement upon the length, slope, width, shape, discharge, velocity, and roughness coefficient of the natural stream between Rulo, Nebr., and Sioux City, Iowa. Data are supplied as to the bed and suspended sediment characteristics of the river, in both improved and unimproved sections. An analysis is presented of the applicability of various bed-load formulas, involving both competence and capacity, to the prediction of the future slope of the river; and results are compared with observations to date (1940) on completed sections of the river. It is generally concluded that: (1) Formulas involving competence will not give the answer to this particular problem; (2) the mean slope of the Missouri River eventually will decrease through the operation of the contraction works; and (3) the bed of the river will scour out progressively for some time to come.