Meanders caused by hyperconcentrated water flow: An example from the loess plateau, China

Abstract

This paper describes meandering alluvial rivers with mean annual suspended-sediment concentrations of more than 100 kgm-3 on the Loess Plateau, China, and explains their formation as caused by the effect of hyperconcentrated water flow. When the river is dominated by hyperconcentrated flow, the rate of energy expenditure required for sediment transport declines significantly. Accordingly, the river channel adjusts itself to a lower channel gradient by increasing the river length, resulting in a meandering channel. Since the stable transportation of sediment by hyperconcentrated flow is dependent on river channel boundary conditions, the latter play an important role in the formation of meanders of this kind. The paper also discusses the conditions for the discrimination of meandering and braided rivers in this area. KEY WORDS Meanders Hyperconcentrated flow Channel boundary conditions Potential energy expenditure rate

Hyperconcentrated flows in the slope‐channel systems in gullied hilly areas on the loess plateau, china

“…Hyperconcetrated flows have been observed in various natural settings in the world (Batalla et al 1999;Wijdenes and Ergenzinger 1998;Cannon, et al 1998;Wan 1985;Englund and Wan 1984), drawing attention from geologists, geomorphologists and hydraulic engineers. In the Loess Plateau region of China, where hyperconcentrated flows are well developed and widely distributed, much research has been done in the past 20 years (Wang et al 1982, Zhang, et al 1982, Chien and Wan 1983, Chien 1989, Xu 1993, 1997, 1998, 1999, 2000, since the pioneering work by Chien and coworkers (Chien et al 1979). Hyperconcentrated flows are regarded as a major hazardous streamflow in the lower Yellow River because they often result in strong scouring and deposition and abnormal changes of water discharge and water level, all leading to serious difficulties in flood protection (Chien 1989).…”