Title: Effect of non-uniformity of sediment size on the Movability Number

Authors: Aamer Majid Bhat; Manzoor Ahmad Ahanger

Addresses: Department of Civil Engineering, National Institute of Technology Srinagar, Jammu and Kashmir, India ' Department of Civil Engineering, National Institute of Technology Srinagar, Jammu and Kashmir, India

Abstract: Sediment on a channel bed is generally not composed of particles of the same size. This non-uniformity affects its incipient motion condition. As a model of an otherwise very complicated situation, two sediment sizes are considered here. A single parameter of non-uniformity is the ratio d/D of the two sizes, where d is the overlying moving sediment size and D the size of the underlying sediment. This study, with the help of experimental data of previous researchers, examines the influence of non-uniformity of sediment on the parameter of incipient motion, critical Movability Number. The empirical curves given by three different studies for uniform sediment are examined in the more general non-uniform context. It is found that the critical Movability Number decreases when the d/D ratio increases, that is, as the overlying sediment size increases and there is less likelihood of grains being hidden in interstices of the underlying layer. However, other factors like specific gravity, size, and the sediment surface features of the sediment have their individual influence on its determination.

Keywords: channel bed; non-uniformity; incipient motion; sediment sizes; critical Movability Number; specific gravity.

DOI: 10.1504/IJHST.2022.126428

International Journal of Hydrology Science and Technology, 2022 Vol.14 No.4, pp.375 - 389

Received: 15 Jul 2020
Accepted: 13 Jan 2021
Published online: 26 Oct 2022 *

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