Manning roughness coefficient in vegetated open channels

Elmoaty, Mohamed Salah Abd; El-Samman, Tarek A.

doi:10.1080/11104929.2020.1794706

Cited by 10 publications

(8 citation statements)

References 8 publications

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“…The particle size of the bed material has significant effects on the Manning roughness coefficient. In general, as particle size expands, Manning's roughness coefficient decreases ([ 42 , 45 , [46] , [73] , [74] , [75] , [76] , [77] ]; Salah Abd Elmoaty & T. A., 2020; [ 25 ]). The real effect of the bed on the coefficient of discharge would remain intangible as long as existing calculations are not modified to reflect the aggregate size.…”

Section: Resultsmentioning

confidence: 99%

Acclimatize experimental approach to adjudicate hydraulic coefficients under different bed material configurations and slopes with and without weir

Amsie,

Ayalew,

Mada

et al. 2024

Heliyon

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Section: Resultsmentioning

confidence: 99%

Acclimatize experimental approach to adjudicate hydraulic coefficients under different bed material configurations and slopes with and without weir

Amsie,

Ayalew,

Mada

et al. 2024

Heliyon

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“…Vegetation density significantly affects the overall flow behaviour in the vegetated Y‐shaped confluence (Gran & Paola, 2001). The vegetation density was demonstrated as the dominant parameter that influences Manning's roughness coefficient ( n ) within the vegetated channel (Salah Abd Elmoaty & El‐Samman, 2020). The flexible vegetation density (200 items/m 2 ) is larger than that in the previous similar studies such as 10–90 (Li et al, 2014), 35–84 (Lacy & Wyllie‐Echeverria, 2011), 12 (Liu et al, 2013) items/m 2 .…”

Section: Discussionmentioning

confidence: 99%

An experimental study of the hydrodynamics and contaminant transport in a Y‐shaped confluence with flexible submerged vegetation

Tong

Liu

Yang

et al. 2022

Hydrological Processes

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Vegetation greatly affects the flow characteristics and contaminant transport in river confluences. In this study, the flow characteristics and contaminant transport in the non‐vegetated/vegetated Y‐shaped confluence were explored systematically through a series of experiments. A total of 10 scenarios were designed to answer the three main research questions: what is the difference between the flow characteristics and contaminant transport in (1) asymmetrical and Y‐shaped confluences; (2) non‐vegetated/vegetated Y‐shaped confluences; (3) vegetated Y‐shaped confluences with different confluence ratios? The experimental results revealed that vegetation remarkably changes the internal flow structure in Y‐shaped confluences. Briefly, the velocity profile can be divided into three vertical layers within the vegetated system, but it remains nearly constant in the non‐vegetated channel. Vegetation changes the circulation location and reduces the intensity of the secondary current, weakening the strength of contaminant mixing. However, the turbulent kinetic energy within the vegetated system is larger than that in the non‐vegetated case, and it peaks at the top of the vegetation canopy. Under different confluence ratio cases, the overall fluctuation of the longitudinal dispersion coefficients along the cross‐sections in the mainstream was similar but increasing the confluence ratio causes the circulation to appear to advance and enhances its intensity. In addition, the vegetation density (200 item/m2) in this study render the manning roughness coefficient at 0.068, which is larger than that under lower vegetation density cases. The outcomes from this study are helpful for both environmental and river management applications.

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“…The flow rate in grass swales is typically calculated using Manning's equation [22][23][24], as represented by Equation (2).…”

Section: Manning's Equationmentioning

confidence: 99%

A Modified Manning’s Equation for Estimating Flow Rate in Grass Swales under Low Inflow Rate Conditions

Wang,

Qiu,

Xia

et al. 2024

Water

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As green infrastructure has evolved, grass swales have become integral components of stormwater management. Manning’s equation is commonly used to describe the hydraulic characteristics of grass swales. However, due to flow loss from infiltration, grass swales often deviate from the assumptions of Manning’s equation, potentially leading to significant errors in grass swale flow rate calculations. In this study, we systematically investigated changes in flow rates in grass swales under various constant inflow rate conditions. The results indicated that the suitability of using Manning’s equation to estimate flow rate in grass swales varies with inflow rate. At an inflow rate of 3.00 m3/h, the discrepancy between the measured and the estimated flow rates by Manning’s equation was the smallest, ranging from −0.24 to 0.19 m3/h. At lower inflow rates (1.00 to 2.00 m3/h), Manning’s equation underestimated the flow rates by 0.16 to 0.47 m3/h; at higher rates (4.00 m3/h), it overestimated the flow rates by 0.01 to 0.61 m3/h. Considering infiltration losses as the primary cause of these errors, we proposed an improved Darcy’s formula for estimating the infiltration rates in grass swales, along with a modified Manning’s equation for more accurate flow rate calculations. The modified Manning’s equation provides enhanced accuracy in calculating flow rates in grass swales compared to the traditional version.

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Manning roughness coefficient in vegetated open channels

Cited by 10 publications

References 8 publications

Acclimatize experimental approach to adjudicate hydraulic coefficients under different bed material configurations and slopes with and without weir

Acclimatize experimental approach to adjudicate hydraulic coefficients under different bed material configurations and slopes with and without weir

An experimental study of the hydrodynamics and contaminant transport in a Y‐shaped confluence with flexible submerged vegetation

A Modified Manning’s Equation for Estimating Flow Rate in Grass Swales under Low Inflow Rate Conditions

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