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Summary of alluvial channel data from flume experiments, 1956-61

1966; United States Government Publishing Office; Linguagem: Inglês

10.3133/pp462i

2330-7102

Harold P. Guy, Daryl B. Simons, E. V. Richardson,

Hydrology and Watershed Management Studies

Alluvial channel.A channel whose bed is composed of noncohesive material that has been or can be transported by the flow.Antidunes.Bed features that usually form in upstream-moving trains and are inphase with and strongly interact with gravity water-surface waves.The flow is in the upper flow regime; therefore, the water-surface waves have larger amplitudes than the antidunes.At higher Froude numbers, the surface waves usually grow until they become unstable and break in the upstream direction.The agitation accompanying breaking obliterates the antidunes, and the process of antidune initiation and growth is then repeated.At lower Froude numbers, the antidunes usually diminish in amplitude without the surface waves ever breaking.Bar.A depositional feature whose length is of the same order as the channel width or greater, and whose maximum height is comparable to the mean depth of the generating flow.In longitudinal section, bars are approximately triangular, having very long gentle upstream slopes and short downstream slopes that are approximately the same as the angle of repose of the bed material.Alternate bars and point bars have transverse profiles that are triangular and taper from the bank to a point in the channel.Bed material.The material of which a streambed is composed.Clay.Sediment finer than 0.004 mm (millimeter), regardless of mineralogical composition.Chute-and-pool flow.A flow condition that occurs where slopes are relatively steep and water-sediment discharges are relatively great, the channel consists of a series of pools, in which the flow is subcritical, connected by steep chutes, in which the flow is supercritical.A hydraulic jump forms at the downstream end of each chute, where the chute enters a pool.The chutes and pools may move slowly upstream.