Retardance coefficient of vegetated channels estimated by the Froude number

Chen, Yen‐Chang; Kao, Sung‐Shuo; Lin, Jen‐Yang; Yang, Han‐Chung

doi:10.1016/j.ecoleng.2009.03.002

Cited by 25 publications

(19 citation statements)

References 18 publications

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“…The slightly higher values in the Manning's roughness can be attributed to the fact that the simulation and the experiments were carried on flatbeds with no slope and also the fact that the whole flume length of 10 m was tested in the experiment and simulated with the single module installed. These findings are in agreement with the work of Choo et al [31] and Cheng et al [32] who observed Manning's coefficient variations under greater flow depth.…”

Section: Free Flow Without Module and Flow With Modulesupporting

confidence: 94%

Modelling of Flow Parameters through Subsurface Drainage Modules for Application in BIOECODS

Abdurrasheed

Yusof

Al‐Qadami

et al. 2019

Water

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The flow resistance of the existing modules in the bio-ecological drainage system (BIOECODS) is high and may lead to flood instead of its mitigation. As part of efforts to enhance the performance of the system, the river engineering and urban drainage research center (REDAC) module was developed. This study modelled the hydrodynamics of flow through this module using FLOW-3D and laboratory experiments for two cases of free flow without module (FFWM) and flow with a module (FWM) to understand and visualize the effects of the module. With less than 5% error between the numerical and experimental results, REDAC module altered the flow pattern and created resistance by increasing the Manning's roughness coefficient at the upstream, depth-averaged flow velocity (43.50 cm/s to about 46.50 cm/s) at the downstream and decreasing water depth (7.75-6.50 cm). These variations can be attributed to the complex nature of the module pattern with further increase across the porous openings. Therefore, the technique used herein can be applied to characterize the behavior of fluids in larger arrangments of modules and under different flow conditions without the need for expensive laboratory experiments.

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Section: Free Flow Without Module and Flow With Modulesupporting

confidence: 94%

Modelling of Flow Parameters through Subsurface Drainage Modules for Application in BIOECODS

Abdurrasheed

Yusof

Al‐Qadami

et al. 2019

Water

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“…Wilson et al also developed a procedure for predicting Manning's roughness coefficient n and found that Manning's n increases with decreasing flow depth until it reaches an asymptotic constant [15]. In the research of Chen et al, the experimental analysis of hydraulic parameters indicated that there are strong correlations between the retardance coefficient and the Froude number [16]. Wu et al proposed a vegetative characteristic k to represent the consistent trend of the variation for the drag coefficient versus the Reynolds number [17].…”

Section: Introductionmentioning

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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“…Overall, the BIOECODS is considered effective in terms of providing flow attenuation, ensuring quality and quantity control of the stormwater with great prospects of mitigating flooding in Malaysia. Recently, several studies have been conducted to determine the flow resistance and Manning's n at the channel with submerged and unsubmerged vegetation [39]. In the vegetated channel, Manning's coefficient is known as the retardance coefficient and the plant's height is recognized as a significant parameter to estimate roughness [40].…”

Section: Review Of Previous Work On Bioecods and Drainage Modulementioning

confidence: 99%

Advances and Challenging Issues in Subsurface Drainage Module Technology and BIOECODS: A Review

et al. 2018

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Subsurface drainage modules are important components of the Bio-ecological Drainage System (BIOECODS) which is a system designed to manage stormwater quantity and quality using constructed grass swales, subsurface modules, dry and wet ponds. BIOECODS is gradually gaining attention as one of the most ecologically sustainable solutions to the frequent flash floods in Malaysia and the rest of the world with a focus on the impact of the subsurface modules to the effectiveness of the system. Nearly two decades of post-construction research in the BIOECODS technology, there is need to review findings and areas of improvement in the system. Thus, this study highlighted the key advances and challenges in these subsurface drainage modules through an extensive review of related literature. From the study, more work is required on the hydraulic characteristics, flow attenuation and direct validation methods between field, laboratory, and numerical data. Also, there is concern over the loss of efficiency during the design life especially the infiltration capacity of the module, the state of the geotextile and hydronet over time. It is recommended for the sake of higher performance, that there should be an onsite methodology to assess the permeability, rate of clogging and condition of the geotextile as well as the hydronet over time.

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Retardance coefficient of vegetated channels estimated by the Froude number

Cited by 25 publications

References 18 publications

Modelling of Flow Parameters through Subsurface Drainage Modules for Application in BIOECODS

Modelling of Flow Parameters through Subsurface Drainage Modules for Application in BIOECODS

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

Advances and Challenging Issues in Subsurface Drainage Module Technology and BIOECODS: A Review

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