DEGRADATION OF GRADED-MATERIAL BEDS IN SEDIMENT-DEFICIENT RIVERS
摘要
The unsteady channel-degradation problem is formulated for the case of graded bed material by, first, deriving a relation between degradation depth and median particle size in the bed layer that is actively participating in the transport process, and introduction of the resulting equation and an expression for sediment discharge as a function of bed slope and particle size into the sedimentcontinuity equation. The resulting second-order nonlinear partial differential equation for degradation depth is first linearized and solved in closed form, and is also solved exactly by an iterative process applied to the complete equation. The latter solutions are found to be in good agreement with data from the Colorado River downstream from Hoover Dam, and with results obtained from a numerical simulation of an idealized representation of the Missouri River.