Complex behaviour of natural sediment-carrying streamflows and the geomorphological implications

Based on the data from alluvial rivers in China, the complex mechanical behaviour of sediment-carrying streamflow of natural rivers has been observed. Channel geometry also exhibits complex behaviour in response to variation in suspended concentration. With the increase in suspended concentration, channel width:depth ratio increases, reaches a maximum and then decreases. The inverse is true for channel sinuosity. When suspended concentration is low, a meandering pattern is dominant. The increase in suspended concentration leads to a transformation from a meandering to a braided pattern. But when the suspended concentration increases further and enters the range of hyperconcentrated flows, the meandering pattern appears. The complex behaviour of channel pattern change may be regarded as a reflection of the complex behaviour of sediment-carrying streamflows at the river reach scale. Copyright (C) 2002 John Wiley Sons, Ltd