MEANDERS CAUSED BY HYPERCONCENTRATED WATER-FLOW - AN EXAMPLE FROM THELOESS PLATEAU, CHINA

This paper describes meandering alluvial rivers with mean annual suspe nded-sediment concentrations of more than 100 kg m(-3) on the Loess Pl ateau, China, and explains their formation as caused by the effect of hyperconcentrated water how. When the river is dominated by hyperconce ntrated flow, the rate of energy expenditure required for sediment tra nsport declines significantly. Accordingly, the river channel adjusts itself to a lower channel gradient by increasing the river length, res ulting in a meandering channel. Since the stable transportation of sed iment by hyperconcentrated flow is dependent on river channel boundary conditions, the latter play an important role in the formation of mea nders of this kind. The paper also discusses the conditions for the di scrimination of meandering and braided rivers in this area.