Effect of flexible vegetation lodging on overland run‐off resistance

Zhang, Shengtang; Liu, Ying; Wang, Zhikai; Li, Guibao

doi:10.1111/wej.12529

Cited by 3 publications

(2 citation statements)

References 26 publications

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“…In addition, aquatic canopies can also provide resistance by raising the local water levels in rivers and reducing the flow velocity. Therefore, investigating the turbulence structure in water bodies under the influence of vegetation canopy can help further the understanding of pollutant and sediment transport (Nepf, 2011;Park and Hwang, 2019;Zhang et al, 2019;Abdolahpour et al, 2020). It can also shed light on the water transport and flooding capacity of the river, which has important implications for ecological restoration projects (Waycott et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics affected by submerged vegetation with different flexibility under unidirectional flow

Chen-hui

et al. 2023

Front. Mar. Sci.

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Submerged vegetation changes the hydrodynamic characteristics of rivers, lakes, wetlands, and coastal zones. However, only a few studies have focused on the effect of flexible submerged vegetation on hydrodynamic characteristics under unidirectional flow. Therefore, laboratory experiments were conducted to study the effects of submerged vegetation with different flexibility on the flow structure and turbulence characteristics under unidirectional flow. The results showed that the reconfiguration and coordination of wave motion of flexible submerged vegetation redistribute flow velocity, Reynolds stress, and turbulent kinetic energy inside and outside of the vegetation canopy. With a gradual decrease in the deflection height of vegetation, the differences in dimensionless velocity, dimensionless mixed layer thickness, bulk drag coefficient, averaged turbulent kinetic energy, and the averaged contribution rate of its shear production term for the vegetation canopy also decrease; the trend of the penetration depth of Reynolds stress is opposite. Based on the turbulent kinetic energy budget equation, a turbulent kinetic energy model (TKE model) was established, which can be used to predict the turbulent kinetic energy and its shear production term within the vegetation canopy. Here, the scaling factor was determined by the vegetation canopy Cauchy number. The TKE model can be applied under unidirectional flow conditions for submerged vegetation with different flexibilities with high accuracy. It is a simple method to predict vegetation-induced turbulence and the characteristics of sediment and material transport under the influence of submerged vegetation with different flexibility.

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Section: Introductionmentioning

confidence: 99%

Hydrodynamics affected by submerged vegetation with different flexibility under unidirectional flow

Chen-hui

et al. 2023

Front. Mar. Sci.

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“…The above research shows that the f–Re relation is affected by vegetation types and underlying surface conditions, which indicates that Re is not the only factor to predict the resistance coefficient (Wang et al, 2018). In fact, f is also affected by vegetation coverage (Li et al, 2013; Shang et al, 2020), stem diameter (Zhang et al, 2018; Zhao et al, 2015), slope gradient (Zhang, Liu, et al, 2019), and water depth (Baptist et al, 2010). The above studies indicated that the resistance mechanism of the overland flow is complicated and the controlling factors of all variables involved and the resistance coefficient f need to be studied in depth.…”

Section: Introductionmentioning

confidence: 99%

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

Cen

Zhang

Peng

et al. 2022

Hydrological Processes

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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).

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