Title: Experimental observations on fine sand winnowing from immobile gravel substrate
Abstract: Introduction of fine sand into gravel-bed rivers has surged tremendously as a result of human activities. The ecological concerns for river habitats have called for suitable management strategies for cleaning these particles from gravel bed rivers. This paper is concerned with determining movement threshold of fine sand initially entrapped in the spaces between large immobile elements resembling a coarse riverine substrate with flow depths comparable to non-erodible element sizes. Static equilibrium condition was reached during an experimental run by maintaining a zero-supply condition for sand. It was assumed that the flow condition corresponding to this sand level was representative of critical conditions for onset of sand motion. A nonlinear regression curve was fitted between the level of the sand and associated critical shear stress. The flow field measurements using an ultrasonic Doppler rofiler delineate main features of the shallow flow over large roughness elements such as sharp velocity gradients near the crest of the immobile elements, and also a deviation of instantaneous velocity probability density function from normal distribution very close to the sand level.
Publication Year: 2020
Publication Date: 2020-08-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 3
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