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A Predictive Equation for the Bed Development Time of Alluvial Meandering Streams

Author(s): Andrew D. Binns; Ana Maria Ferreira Da Silva

Linked Author(s): Ana Maria Ferreira da Silva

Keywords: Meandering streams; Pool-bar complexes; Equilibrium; Laboratory tests; Bed development time

Abstract: An equation for the bed development time of alluvial meandering streams is introduced. In agreement with the prevailing approach, it is assumed that the stream centreline follows a sine-generated curve; the banks are rigid; the flow is turbulent and subcritical; and the width-to-depth ratio is “large”. The bed is flat at the beginning of an “experiment” (i. e., at time t = 0). The bed development consists of the formation of large-scale, laterally adjacent pool-bar complexes strictly induced by the stream curvature. The derivation of the present equation rests on dimensional and physical considerations. It is found that the bed development time is proportional to the square of the flow width and inversely proportional to the specific volumetric bed-load corresponding to the channel-averaged flow. The proportionality factor is a not yet known function of the stream initial deflection angle. To bring the present equation into a form suitable for practical applications, the form of this function is revealed on the basis of a series of experiments carried out by the authors in three sine-generated meandering streams of varying sinuosity.

DOI:

Year: 2013

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