Analytical solutions of velocity profile in flow through submerged vegetation with variable frontal width

Wang, Weijie; Huai, Wenxin; Li, Shuolin; Wang, Ping; Wang, Yufei; Zhang, Jiao

doi:10.1016/j.jhydrol.2019.124088

Cited by 27 publications

(8 citation statements)

References 55 publications

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“…This model better describes the actual flow of the sediment. In addition, the average resistance coefficient C D of the vegetation stem was extracted from Case 1, which was close to the theoretical analysis results of Wang et al (2019), indicating that the model was accurate in simulating water flow with vegetation. Therefore, the model adopted in this study can reasonably affect the flow movement and the hyporheic exchange process near the SWI.…”

Section: Resultssupporting

confidence: 84%

Numerical simulation of hyporheic exchange driven by an emergent vegetation patch

Gao

Sun

2022

Hydrological Processes

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Vegetation patches increase the pressure gradient of local channels and can create an uneven pressure distribution at the water–sediment interface, thereby driving hyporheic exchange. However, this process has rarely been discussed. We investigated the spatiotemporal characteristics of hyporheic exchange under the influence of multiple factors. A bidirectional coupling model of the overlying water and sediment with an emergent vegetation patch was adopted. The results show that hyporheic exchange driven by vegetation patches are spatially heterogeneous. The active area of hyporheic exchange was concentrated directly below the vegetation patch. A finger flow was formed at the edge of the active hyporheic exchange zone as the exchange took place. Furthermore, intermittent downward solute transport path (IDSTP) was formed downstream of the vegetation patch, and the exchange rate was one order of magnitude smaller than that of the hyporheic exchange active zone. Hyporheic exchange occurred at the stem and patch scales when the vegetation density was relatively high. There was a logarithmic relationship between the hyporheic exchange flux and sediment permeability, and a power function relationship existed between the hyporheic exchange flux and Reynolds number. The active area of hyporheic exchange will help predict pollutant transport and understand vegetation's nutrient absorption process. IDSTP will provide references for vegetation patch expansion.

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Section: Resultssupporting

confidence: 84%

Numerical simulation of hyporheic exchange driven by an emergent vegetation patch

Gao

Sun

2022

Hydrological Processes

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“…Vegetation plays a crucial role in natural river ecosystems and considerably influences the movement of water flow and solid particles, for instance, by redistributing the profiles of velocity (Nepf, 2012a; Tang, 2019; Wang et al., 2019), Reynolds shear stress (Dijkstra & Uittenbogaard, 2010; Huai, Zhang, et al., 2019) and suspended sediment concentration (SSC; Huai et al., 2020; D. Li et al., 2020; Y. Li et al., 2020a). Suspended sediment is the main material transported in rivers and is also a carrier for nutrients, such as nitrogen and phosphorus (Ding et al., 2019; Huang et al., 2015; Zhou et al., 2013).…”

Section: Introductionmentioning

confidence: 99%

Study of Suspended Sediment Diffusion Coefficients in Submerged Vegetation Flow

Yang

Guo

2022

Water Resources Research

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The traditional profile model of the sediment diffusion coefficient (εs ${\varepsilon }_{s}$), which is parabolic along the water depth, cannot precisely predict the vertical distribution of εs ${\varepsilon }_{s}$ in vegetated flow. Therefore, in this study, a series of flume experiments were conducted to clarify the influence of submerged vegetation on the diffusion characteristics of suspended load particles. First, the submerged canopy increases the efficiency of momentum exchange but restrains the vertical diffusion of suspended sediment, indicating that the presence of submerged plants promotes the siltation of solid particles. Second, the depth‐averaged sediment diffusion coefficient (εstrue¯ $\bar{{\varepsilon }_{s}}$) monotonically decreases with increasing relative water depth, while the depth‐averaged momentum exchange coefficient (εmtrue¯ $\bar{{\varepsilon }_{m}}$) presents two opposite trends, likely owing to the dominant turbulence event changing from ejections to sweeps and the different variation tendencies of the velocity gradient and Reynolds shear stress with increasing vegetation density. Compared with the ratio (β $\beta $) of εs ${\varepsilon }_{s}$ to the momentum exchange coefficient in nonvegetated flow, β $\beta $ in submerged canopy flow is significantly less than 1, which means that the solid particles diffuse less readily than liquid particles because of the stem‐scale vortices generated by the vegetation. In addition, vertical profile models of εs ${\varepsilon }_{s}$ and suspended sediment concentration were proposed and validated by experimental data. The models exhibit a high accuracy, correlation and applicability and can provide critical information to promote research on riverbed deformation and nutrient dynamics in vegetated rivers, wetlands and estuaries.

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“…In channels with submerged vegetation, the longitudinal dispersion coefficient increases sharply relative to emergent conditions because the multilayer flow structure increases the vertical velocity gradient [48][49] . As shown in Fig.…”

Section: Submerged Vegetationmentioning

confidence: 99%

Longitudinal dispersive coefficient in channels with aquatic vegetation: A review

Yang¹,

Fang²,

Yang³

et al. 2023

J Hydrodyn

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The determination of longitudinal dispersion coefficient in rivers is necessary for pollution control, environmental risk assessment, and management. In rivers with aquatic vegetation, the flow field is remarkably modified by canopies, which affects velocity profiles and dispersion characteristics dominated by the heterogeneity of the velocity field. The dispersion is deduced from lateral and vertical longitudinal velocity gradients for compound channels with vegetated floodplains and rectangular channels with river-wide vegetation, respectively. Although many efforts have been exerted to clarify the dispersion process in different conditions and predict the diffusion of contaminants in vegetated rivers, no studies have introduced it systematically. This study reviews the dispersion coefficient characteristics, including magnitude, main impacted factors, and relationships with flow and vegetation features, in channels with aquatic canopies considering the variation of impact factors changing with the different vegetation and river morphology scenarios. Several typical methodologies for determining longitudinal dispersion coefficients are also summarized to understand the dispersion processes and concepts. Apart from the pioneer outcomes of previous studies, the review also emphasizes the deficiency of existing studies and suggests possible future directions for improving the theory of dispersion in vegetated channels.

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Analytical solutions of velocity profile in flow through submerged vegetation with variable frontal width

Abstract: Flow within vegetation is one of the main driving forces for material exchange and energy transfer in wetland systems. Impacted by vegetation, the flow velocity profile illustrates distortions to the classic logarithmic velocity profile and has attracted much attention among researchers.

Cited by 27 publications

References 55 publications

Numerical simulation of hyporheic exchange driven by an emergent vegetation patch

Numerical simulation of hyporheic exchange driven by an emergent vegetation patch

Study of Suspended Sediment Diffusion Coefficients in Submerged Vegetation Flow

Longitudinal dispersive coefficient in channels with aquatic vegetation: A review

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