Experimental study on the effect of simulated grass and stem coverage on resistance coefficient of overland flow

Youdong Cen, Kuandi Zhang, Yong Peng, Matteo Rubinato, Juanjuan Liu, Peng Ling

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3 Citations (Scopus)
24 Downloads (Pure)


Vegetation plays a significant role in preventing desertification, conservation of soil and water. However, nowadays, there is still uncertainty regarding the mechanisms of flow resistance caused by dissimilar vegetation covers. To address this gap, a series of these was conducted in this study to investigate the influence of synthetic grass and stems on the variation of resistance on overland flows. Thirty vegetation configurations were selected (combining five synthetic grass coverage options and six synthetic stem coverage ones), and tested against five unit discharges (flow range = 0.28–2.22 L m−1 s−1) and four slope gradients (3.49%–20.78%). The results obtained showed that the unit discharge is the key driving factor for the transition from laminar to transitional flow. Furthermore, the relationship between the resistance coefficient (f) and the Reynolds number (Re) was not monotonically increasing or decreasing, but behaviours observed were specifically linked to each vegetation coverage. However, a critical coverage threshold was identified, and it corresponded to 2.72% when the slope gradient tested was 3.49%. This threshold decreased with the increase of the slope gradient. In addition, when the vegetation coverage was less than the critical threshold, the f was negatively correlated with Re, otherwise if the vegetation coverage was higher than the critical threshold identified the f–Re relation was positively correlated. The total flow resistance under synthetic grass and stem cover was unequal to the linear superposition of grain resistance and form resistance caused by synthetic stem and grass, which meant that the linear superposition approach is not applicable to overland flows. Finally, a model was developed to predict the flow resistance by applying the π-theorem and the multiple nonlinear regression analysis and it has been validated against the experimental results confirming its accuracy and high performance (adj.R2 = 0.99, NSE = 0.94).
Original languageEnglish
Article numbere14705
Number of pages17
JournalHydrological Processes
Issue number10
Early online date25 Sept 2022
Publication statusPublished - 9 Oct 2022

Bibliographical note

This is the peer reviewed version of the following article: Cen, Y, Zhang, K, Peng, Y, Rubinato, M, Liu, J & Ling, P 2022, 'Experimental study on the effect of simulated grass and stem coverage on resistance coefficient of overland flow', Hydrological Processes, vol. 36, no. 10, e14705, which has been published in final form at https://doi.org/10.1002/hyp.14705. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.

This document is the author’s post-print version, incorporating any revisions agreed during the peer-review process. Some differences between the published version and this version may remain and you are advised to consult the published version if you wish to cite from it.


This research was financially supported by the National Natural Science Foundation of China (grant numbers 41877076 and 52179079); the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau (grant number A314021402‐202108)


  • flow regime
  • grass and stem cover
  • overland flow
  • resistance coefficient
  • Π-theorem
  • Water Science and Technology


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