SEDIMENT-REMOVING CAPACITY AND RIVER MOTION DYNAMICS
摘要
Unsteady flow in fluvial rivers scours or deposits sediment, and exhibits sediment-removing capaciiy,which is defined as the capacity of the flow to remove sediment from per unit length of a river channel to other places per time. Differing from the well-defined sediment-carrying capacity, which is the feature of the mean flow and explains how much sediment load the flow can transport through the channel, the sediment-removing capacity is the feature of unsteady, non-equilibrium flow and represents the capability of the flow to change the channel shape and location. Measurement of the sediment-removing capacity was performed at 12 cross sections of the wandering lower Yellow River. Analysis demonstrates that the removing capacity depends mainly on the fluctuation intensity of the flow discharge. The power spectrum of discharge is presented with Fourier transformation and it revealed the mechanism of high measurement frequency-high sediment removing capacity. The movement of a river channel within the fluvial plain is defined as the river motion. The patterns of river motion are aggradation, degradation, widening,translation, rotation, wandering, bifurcation, and migration from one channel to another channel. The speed of the river motion is given as a function of the sediment-removing capacity.