Impact of Vegetation on Bed Load Transport Rate and Bedform Characteristics
Name
Yang_WRR_2019.pdf
Description
Published version
Size
2.06 MB
Format
Adobe PDF
Checksum (MD5)
4be903da136c0a9d7c0b4d0f24fa3b1f
Author(s)
Yang, Qingjun (Judy Qingjun)
Nepf, Heidi
Date Issued
July 2019
Journal
Water Resources Research
Publisher
American Geophysical Union (AGU)
Citation
Yang, J. Q. and H. M. Nepf, "Impact of Vegetation on Bed Load Transport Rate and Bedform Characteristics." Water Resources Research 55, 7 (July 2019): 6109-24 doi. 10.1029/2018WR024404 ©2019 Authors
Version
Final published version
Abstract
The impacts of aquatic vegetation on bed load transport rate and bedform characteristics were quantified using flume measurements with model emergent vegetation. First, a model for predicting the turbulent kinetic energy, kt, in vegetated channels from channel average velocity U and vegetation volume fraction ϕ was validated for mobile sediment beds. Second, using data from several studies, the predicted kt was shown to be a good predictor of bed load transport rate, Qs, allowing Qs to be predicted from U and ϕ for vegetated channels. The control of Qs by kt was explained by statistics of individual grain motion recorded by a camera, which showed that the number of sediment grains in motion per bed area was correlated with kt. Third, ripples were observed and characterized in channels with and without model vegetation. For low vegetation solid volume fraction (ϕ ≤ 0.012), the ripple wavelength was constrained by stem spacing. However, at higher vegetation solid volume fraction (ϕ=0.025), distinct ripples were not observed, suggesting a transition to sheet flow, which is sediment transport over a plane bed without the formation of bedforms. The fraction of the bed load flux carried by migrating ripples decreased with increasing ϕ, again suggesting that vegetation facilitated the formation of sheet flow. ©2019. American Geophysical Union. All Rights Reserved.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Terms of Use
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1029/2018WR024404
