Experimental Study on Flow Resistance Over Rigid Vegetated Channel

Liu, Xiao-Dong; Tang, Liang-Chuan; Han, Yu; Chen, Jian; Yang, Shu-Qing

doi:10.1109/access.2019.2927691

Cited by 4 publications

(4 citation statements)

References 23 publications

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“…The load cell is located at the middle part of the experimental section. The working principle of load cell has been detailed in the Liu et al [32]. As shown in Fig.5, only the vegetation sticks interacts with flow and the experimental board (it can be viewed as ''channel bed'') is not 'submerged in flow so the skin friction does not act on the load cell.…”

Section: Methodsmentioning

confidence: 99%

“…The x is the flow direction and y is the flow depth direction of channel. The working principle has been explained in detail by Liu et al's study [32]. The Fig.7 shows longitudinal average flow velocity and the experimental condition is the Q = 100m 3 /h and one-row sticks act as one vegetation patch.…”

Section: A Determination Of the Longitudinal Scale Of The Vortex Strmentioning

confidence: 99%

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Estimation of Form Drag Caused by Rigid Vegetation Based on Equivalent Roughness

Liu

Tang

et al. 2019

IEEE Access

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The flow structure over vegetation in ecological channel is rather complex and the resistance caused by vegetation is affected by many factors, such as discharge, flow depth, vegetation density and patch arrangement types, etc. In order to simplify vegetation characteristics, the rigid cylindrical sticks arranged in the open channel were used to simulate the stems of non-submerged vegetation. The volume of the vortex structure near the vegetation patch can be determined through velocity distribution in vegetated channel and the velocity distribution is measured by Acoustic Doppler Velocity meter. A new formula of equivalent roughness based on the vortex volume near the vegetation patch has been proposed and the form drag can be further determined by the new equivalent roughness. Based on theoretical analysis and experimental results, it shows the vortex volume plays an important role on flow resistance caused by vegetation. The theoretical and experimental results on form drag achieve a good agreement on various experimental conditions. The relation between the relative roughness and relative vortex length was also derived and verified by different experimental conductions. For the dependence of relative roughness on vegetation density, the empirical formula between relative roughness and vegetation density was further proposed and analyzed. INDEX TERMS Form drag, equivalent roughness, vortex structure, rigid vegetation, open channel.

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Section: Methodsmentioning

confidence: 99%

Section: A Determination Of the Longitudinal Scale Of The Vortex Strmentioning

confidence: 99%

Estimation of Form Drag Caused by Rigid Vegetation Based on Equivalent Roughness

Liu

Tang

et al. 2019

IEEE Access

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“…In 1959, Chow suggested in the look-up tables of his book that the vegetation component of Manning's coefficient could be 0.1 with very high vegetation [3]. This traditional method is not very accurate because of the complexity of vegetation types, densities and distributions [33], [34]. The theoretical considerations and experimental analysis on the variation of the water depth of gradually varied flow in the vegetated channel in this study revealed that the Manning's coefficient varied along the flow direction and that such variation had a certain regularity.…”

Section: B Variations Of the Total Manning's Coefficient Along The Vegetated Channelmentioning

confidence: 99%

Determination of Emergent Vegetation Effects on Manning’s Coefficient of Gradually Varied Flow

Zhang

Wang

et al. 2019

IEEE Access

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Based on mechanical derivation, a new formula showing the effects of emergent vegetation on Manning's coefficient was established for complex gradually varied flow affected by rigid unsubmerged vegetation in open channels. The new formula indicates that the Manning's coefficient is a quadratic sum of its vegetal and boundary components with coefficients related to vegetation parameters. The variation characteristics of the total Manning's coefficient and its vegetal component calculated by the new formula were investigated by a series of laboratory experiments under different vegetation coverage area ratios. It was found that the variations of both the total Manning's coefficient and its vegetal component followed a linear decreasing trend along the vegetation section. Moreover, linear and power empirical formulas were constructed for the average total Manning's coefficient and its vegetal component related to the vegetation coverage area ratio, respectively. The findings of the research may expand the theoretical connotations of the Manning's coefficient for open channel hydraulics and demonstrate practical significance to engineering applications of the Manning's coefficient for gradually varied flow in vegetated channels. INDEX TERMS Manning's coefficient, vegetal component of Manning's coefficient, rigid unsubmerged vegetation, gradually varied flow, vegetation coverage area ratio.

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“…Behind the advantages of sided vegetation from increases bank stability, reduces erosion, provides habitat for aquatic life, and filters pollutants [1,2], its excessive existence of it causes many hydraulic problems. Such as water velocity reduction, water level rising, decrease water flow, un-efficient water distribution, etc.…”

Section: Introductionmentioning

confidence: 99%

Heading Up and Head Losses Estimation Due to Rigid Bank Vegetation

Eraky¹,

El-Refaae²,

Abdelmoaty³

et al. 2023

Engineering Research Journal - Faculty of Engineering (Shoubra)

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Water surface profile is an important tool to design and manage hydraulic structures and watercourses flood control. However, limited studies focused on the effect of aquatic vegetation on the water depths in open channels. So the purpose of this paper is to investigate, how the density and distribution of the rigid bank vegetation affect the water depths in terms of heading up and head losses. Eighty-four tests were used, where tests were run for three vegetation densities (0.0113, 0.0028, and 0.0013) along 4.00 m fixed reach with varying Froude number. Water surface profiles were measured and plotted for all cases where it is observed that the water depth increased upstream the vegetated reach then lowered within it and gradually back to the normal depth downstream the vegetated reach. Empirical equations were deduced to determine the heading up and the head losses due to bank vegetation as a function in the vegetation density and the Froude number. The research presented empirical equations that assist in water management in vegetated open channels.

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Experimental Study on Flow Resistance Over Rigid Vegetated Channel

Cited by 4 publications

References 23 publications

Estimation of Form Drag Caused by Rigid Vegetation Based on Equivalent Roughness

Estimation of Form Drag Caused by Rigid Vegetation Based on Equivalent Roughness

Determination of Emergent Vegetation Effects on Manning’s Coefficient of Gradually Varied Flow

Heading Up and Head Losses Estimation Due to Rigid Bank Vegetation

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