Movable Bed Model for River Structures Design

Laboratory tests using a movable bed hydraulic model were conducted to develop optimum design criteria for a new type river control structure called an L-head dike. The large size of the prototype, the Missouri River, made it necessary to distort the model, thus requiring careful consideration of the various scale factors. Rates of sediment transport strongly influence bed roughness, therefore it was important that the movable bed material be light to permit transport at low velocities. Ground walnut shells were found to satisy not only the sediment transport requirements but also simulated bank caving that occurs in the prototype. Verification tests as well as constant checks on scale factors were performed through the investigation period. The most surprising benefit was the ability of the engineer to observe sediment transport, dune patterns, bed waves, current boils, eddy currents, accretion buildup, and bank erosion.