Analytical model for predicting the lateral profiles of velocities through a partially vegetated channel

Yan, Chunhao; Shan, Yuqi; Liu, Xingnian

doi:10.1016/j.jhydrol.2022.128137

Cited by 8 publications

(4 citation statements)

References 60 publications

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“…The well‐established SKM model is widely employed to simulate depth–mean velocity ( U d ) profiles in two‐stage channels with smooth floodplains. Subsequently, several modified SKM models have been developed, and their application has been improved in vegetated two‐stage channels (e.g., Liu, Luo, Liu, & Yang, 2013; Sanjou et al, 2010; Shiono et al, 2012; Yan et al, 2022; Zhang et al, 2017). However, in all these SKM and modified SKM models, the λ is simplified as a constant in each panel.…”

Section: Discussionmentioning

confidence: 99%

“…Despite their contributions towards reproducing and forecasting the vegetated overbank flow, all of these models incorporate a large number of complex calculations to solve the Navier–Stokes equation. Recently, several researchers have developed analytical models for both emergent and submerged rigid vegetation (Fu et al, 2021; Huai et al, 2009; Huthoff et al, 2007; Konings et al, 2013; Shi et al, 2019; Tang, 2019; Tinoco et al, 2015; Wang et al, 2019; Yan et al, 2022; Yang et al, 2020); these can effectively estimate overbank flow characteristics in a simple manner.…”

Section: Introductionmentioning

confidence: 99%

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An analytical model for transverse velocity distributions of overbank flows with submerged and emergent vegetated floodplains

Liu

Bai

et al. 2023

Hydrological Processes

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The emergence of floodplain vegetation enhances the local drag and affects the velocity distribution of the overbank flow in a two-stage channel. Numerous analytical models (e.g., the modified SKM models) have been established to simulate the transverse velocity distributions of overbank flows with vegetation. However, the dimensionless eddy viscosity (λ) was simplified to be a constant in these models when quantifying transverse momentum exchange. In this paper, we develop a novel analytical model to simulate the depth average velocity profiles of overbank flows with floodplain vegetation. Considering a micro-hexahedral element on a vegetatedbed area for a two-stage rectangular channel, the governing equation of the vegetated overbank flow is derived. An improved eddy viscosity model that considers the transverse variation of the λ is employed to quantify the transverse momentum transfer, and a linear empirical function simplifies the secondary current. The simulated depth average velocities agreed well with the published measurements. In comparison with existing models, the proposed model shows better prediction accuracy, particularly in the shearing layer domain. More importantly, for the optimized model parameters, we found that the dimensionless eddy viscosity plays the most influential role when simulating depth-averaged velocities in the shearing layer domain, whereas the drag force dominates for vegetated floodplains. This study provides a convenient method for predicting the flow velocity in overbank floods with vegetation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An analytical model for transverse velocity distributions of overbank flows with submerged and emergent vegetated floodplains

Liu

Bai

et al. 2023

Hydrological Processes

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“…Regarding an emergent canopy, flow diversion occurs approximately 1 D upstream of the canopy (Rominger & Nepf, 2011; D is the canopy width), resulting in reduced velocity in the vegetated region and enhanced velocity in the adjacent bare channel (e.g., Liu & Shan, 2022). The velocity difference between the vegetated region and bare channel produces a shear layer associated with lateral mass and momentum exchange (e.g., Chen et al., 2010; Yan et al., 2022) and causes bed erosion at the leading and side edges of the canopy (Bouma et al., 2007; Follett & Nepf, 2012; Kim et al., 2015). Within the canopy, it has been confirmed that flow velocity adjustment in the streamwise direction can be expressed by exponential decay (Chen et al., 2013; Zong & Nepf, 2010), and Liu et al.…”

Section: Introductionmentioning

confidence: 99%

Insights for River Restoration: The Impacts of Vegetation Canopy Length and Canopy Discontinuity on Riverbed Evolution

Li,

Shan,

et al. 2024

Water Resources Research

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River restoration projects often involve vegetation planting to retain sediment and stabilize riverbanks. Laboratory experiments have explored the impact of rigid emergent vegetation canopies on bed morphology. Inside canopies, bed erosion is attributed to vegetation‐induced turbulent kinetic energy (TKE). Based on the in‐canopy local TKE and the criteria for sediment movement, a method is established and validated for predicting the length of the bed erosion region. In the bare channel, bed erosion is related to the ratio of canopy length to flow adjustment distance, L/LI, and exhibits two trends. At L/LI < 1, the maximum depth, ds(bare), and length, Ls(bare), of the bed erosion region increase with increasing canopy length. At L/LI ≥ 1, ds(bare) and Ls(bare) are not influenced by the canopy length and remain constant. In vegetated regions with the same length and plant density, discontinuous canopies (streamwise interval s ≥ canopy width D) yield weaker bed erosion than continuous canopies. The mutual influence between two canopies must be considered if the canopy interval satisfies s < 3D. These results provide insights for designing vegetation canopies for river restoration projects.

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“…Originally proposed by Leopold and Wolman [2], braided rivers have distinctive geomorphological features, including scattered and fragmented planforms, easily eroded and deposited sandbars, and channels that are constantly branching and reconfiguring, while the complex movement of water and sediment within these rivers makes their geomorphological units highly dynamic [3,4]. These characteristics make it impossible to predict the evolution of flow velocity and sediment deposition in braided rivers by constructing analytical models, as is the case for straight or meandering rivers [5][6][7][8], and therefore, it is difficult to predict the evolution of braided rivers from the point of view of flow structure. The bed structure of braided rivers is complex and variable due to a variety of factors such as different flow and sediment conditions, particle morphology, grain size gradation, and spatial distribution.…”

Section: Introductionmentioning

confidence: 99%

Statistical Roughness Properties of the Bed Surface in Braided Rivers

Ren

Pan

Lin

et al. 2023

Water

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Braided rivers are widespread in nature, and their bed morphology is complex and variable. This paper aims to investigate and quantitatively analyze the bed surface roughness of braided rivers utilizing statistical theory. In this paper, a physical model of braided rivers is developed, and four constant discharge experiments are carried out. Based on Structure-from-Motion photogrammetry and direct measurement of bedload transport using a load cell, data on bedload transport rate, bed morphology, and bed elevation are obtained, facilitating the in-depth investigation of the correlations between these parameters. The results show that the morphological active width increases with increasing discharge. There was a significant positive correlation between the morphological active width and the bedload transport rate, although there is considerable scatter due to the inherent variability in braided river morphodynamics. The elevation probability distribution of bed surfaces shows negative skewness and leptokurtic distribution. There is a relatively significant correlation between skewness and the dimensionless bedload transport rate. The two-dimensional variogram values of bed elevation are variable, and the bed is anisotropic. Additionally, both the longitudinal sill and correlation length values exhibit an increase with the rise in stream power. Remarkably, the correlation between the dimensionless sill and correlation length, as well as the dimensionless bedload transport rate, proves to be highly significant. Consequently, this correlation can serve as a reliable general factor for predicting bedload transport rate in the reach.

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Analytical model for predicting the lateral profiles of velocities through a partially vegetated channel

Cited by 8 publications

References 60 publications

An analytical model for transverse velocity distributions of overbank flows with submerged and emergent vegetated floodplains

An analytical model for transverse velocity distributions of overbank flows with submerged and emergent vegetated floodplains

Insights for River Restoration: The Impacts of Vegetation Canopy Length and Canopy Discontinuity on Riverbed Evolution

Statistical Roughness Properties of the Bed Surface in Braided Rivers

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