The onset of sediment transport in vegetated channels predicted by turbulent kinetic energy
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Yang_Nepf_Final_manuscript.pdf
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Author(s)
Yang, J. Q.
Chung, H.
Nepf, Heidi
Yang, Qingjun
Chung, Hayoon
Nepf, Heidi
Date Issued
November 2016
Journal
Geophysical Research Letters
Publisher
American Geophysical Union (AGU)/Wiley
Citation
Yang, J. Q., H. Chung, and H. M. Nepf. "The onset of sediment transport in vegetated channels predicted by turbulent kinetic energy." Geophysical Research Letters, Early View article (12 November 2016).
Version
Author's final manuscript
Abstract
This laboratory study advances our understanding of sediment transport in vegetated regions, by describing the impact of stem density on the critical velocity, Ucrit, at which sediment motion is initiated. Sparse emergent vegetation was modeled with rigid cylinders arranged in staggered arrays of different stem densities. The sediment transport rate, Qs, was measured over a range of current speeds using digital imaging, and the critical velocity was selected as the condition at which the magnitude of Qs crossed the noise threshold. For both grain sizes considered here (0.6–0.85 mm and 1.7–2 mm), Ucrit decreased with increasing stem density. This dependence can be explained by a threshold condition based on turbulent kinetic energy, kt, suggesting that near-bed turbulence intensity may be a more important control than bed shear stress on the initiation of sediment motion. The turbulent kinetic energy model unified the bare bed and vegetated channel measurements.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1002/2016GL071092
