Manning's roughness coefficient for ecological subsurface channel with modules

Mohammadpour, Reza; Zainalfikry, Muhammad Kashfy; Zakaria, Nor Azazi; Ghani, Aminuddin Ab.; Chan, Ngai Weng

doi:10.1080/15715124.2019.1672704

Cited by 10 publications

(13 citation statements)

References 26 publications

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“…As a power form, n varied with V r . The data obtained in this study showed the same trend as those obtained by Chen et al [8] in the case of the grassed canal (R 2 = 0.9130 [5], R 2 = 0.9130 [28], and R 2 = 0.9090 [present study]). The values of the present study are less than the values of the previous study.…”

Section: Resultssupporting

confidence: 89%

“…Thus, the Manning relation between grassed and ungrassed canals could be estimated as a function of V r using the following equation: 13) n grass = n un−grass 1.565V 0.39 r Figure 17 shows a comparison between the V r -n relationship obtained in this study and that obtained by Chen et al [5] and Pour et al [28]. As a power form, n varied with V r .…”

Section: Resultsmentioning

confidence: 54%

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Assessment of flow characteristics through a grassed canal

Gad¹,

Sobeih

Rashwan

et al. 2021

Innov. Infrastruct. Solut.

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Vegetation is defined as a kind of surface roughness, which reduces the capacity of the channel and retards the flow by causing loss of energy through turbulence and drag forces of moving water. In water channels, vegetation maybe used to stabilize the water surface and prevent erosion caused by concentrated water flow. In terms of channel lining, grass offers the least expensive option and is the most esthetically pleasing. Most previous studies on this subject were conducted using artificial vegetation in laboratory experiments; research conducted in canals with natural vegetation is lacking. In this study, flow characteristics through a natural grassed canal are studied. In addition, the Manning coefficient and specific energy were determined based on field measurements for both grassed and un-grassed canals. The fieldwork was conducted on Ganabia 9B, southeast of El-Mahalla El Kubra, El-Gharbia, Egypt. The average heights of vegetation in the grassed canal ranged from (28 to 100) cm and the values of flow rate range from (0.0504 to 0.1127) m 3 /s. The number of tests is 42 tests for the un-grassed canal and 205 tests for the grassed canal. This study indicated that the Manning coefficient increased with an increase in energy and momentum coefficients. The energy coefficient increased with a decrease in relative specific energy and an increase in grass height. The un-grassed canal exhibited a smaller relative specific energy than the grassed canal. The momentum coefficients for the non-grassed and grassed canals were 1.015-1.517 and 1.003-1.655, respectively. Therefore, the un-grassed canal showed a higher momentum coefficient than the grassed canal at a ratio of 0.264-1.196%. The relative specific energy was calculated in two ways: (i) using the actual energy coefficient values and (ii) setting it equal to one. As such, the error percentages of the specific energy for the grassed and un-grassed canals were 0.000105-0.1652% and 0.0048-0.2194%, respectively. The results obtained herein were compared with those obtained in previous studies, showing good agreement, but differ in the accuracy of predicting values. Three programs, i.e., gene expression programming, Statistical Package for the Social Sciences, and artificial neural network, were employed to create empirical formulas for modeling the Manning coefficient and relative specific energy for the grassed and un-grassed canals. Gene expression programming was found to be the best modeling program.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 54%

Assessment of flow characteristics through a grassed canal

Gad¹,

Sobeih

Rashwan

et al. 2021

Innov. Infrastruct. Solut.

View full text Add to dashboard Cite

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“…The method of using a ruler for measuring the water depth in the subsurface channels was also reported in some studies conducted by Kee L.C. et al [23] and Mohammadpour R. et al [25].…”

Section: Experimental Set-upmentioning

confidence: 84%

“…Therefore, the majority percentage of urban runoff was removed using infiltration trenches with the use of subsurface perforated and porous drainpipes [7][8][9][10][11][12][13][14][15][16][17][18][19] and using the subsurface modular tanks and channels in biological drainage systems [20][21][22][23][24][25] recommended by the River Engineering and Urban Drainage Research Centre (REDAC) in Malaysia for managing both water quantity and quality in urban areas. Groundwater recharge, low stream flow augmentation, water quality enhancement, and a reduction in the total runoff volume are also among the advantages of using the infiltration practices mentioned in the preceding studies [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The performances of subsurface perforated and porous drainpipes were often used in infiltration trenches for the removal of the urban stormwater runoff [7][8][9][10][11][12]…”

Section: Introductionmentioning

confidence: 99%

Investigating the Relationship between the Manning Coefficients (n) of a Perforated Subsurface Stormwater Drainage Pipe and the Hydraulic Parameters

et al. 2023

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Subsurface perforated pipes drain infiltrated stormwater runoff while attenuating the peak flow. The Manning roughness coefficient (n) was identified as a fundamental parameter for estimating roughness in various subsurface channels. Hence, in this work, the performance of a six-row non-staggered sand-slot perforated pipe as a sample of the subsurface drainage is investigated experimentally in a laboratory flume at Universiti Sains Malaysia (USM) aimed at determining the Manning roughness coefficients (n) of the pipe and assessing the relationship between the Manning’s n and the hydraulic parameters of the simulated runoff flow under the conditions of the tailgate channel being opened fully (GFO) and partially (GPO), as well as the pipe having longitudinal slopes of 1:750 and 1:1000. Water is pumped into the flume at a maximum discharge rate of 35 L/s, and the velocity and depth of the flow are measured at nine points along the inner parts of the pipe. Based on the calculated Reynolds numbers ranging from 38,252 to 64,801 for both GFO and GPO conditions, it is determined that most of the flow in the perforated pipe is turbulent, and the calculated flow discharges and velocities from the outlets under GFO are higher than the flow and velocity rates under GPO with similar pipe slopes of 1:750 and 1:1000. The Manning coefficients are calculated at nine points along the pipe and range from 0.004 to 0.009. Based on the ranges of the calculated Manning’s n, an inverse linear relationships between the Manning coefficients and the flow velocity under GFO and GPO conditions are observed with the R2 of 0.975 and 0.966, as well as 0.819 and 0.992 resulting from predicting the values of flow velocities with the equations v = ((0.01440 − n)/0.009175), v = ((0.01330 − n)/0.00890), v = ((0.02007 − n)/0.01814), and v = ((0.01702 − n)/0.01456) with pipe slopes of 1:750 and 1:1000, respectively. It is concluded that since the roughness coefficient (Manning’s n) of the pipe increases, it is able to reduce the flow velocity in the pipe, resulting in a lower peak of flow and the ability to control the quantity of storm water in the subsurface urban drainages.

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“…where, B is the waterfall width, Q is the water discharge, i is the longitudinal slope and h is the quantified water depth. (Zakaria et al, 2003;Mohammadpour et al, 2020) Figure 4 shows the alteration of Manning persistence factor in contradiction of variations in current degree depend on the overall average depth for 20% gradient. Figure 5 shows the variation of Manning persistence factor in contradiction of variations in current degree depend on the over-all average depth for 30% gradient.…”

Section: Methodsmentioning

confidence: 99%

Impact of the Drainage Slope Experimental Study on the Manning Roughness Coefficient

Ostad‐Ali‐Askari¹,

Gholami²,

Dehghan³

et al. 2021

American Journal of Engineering and Applied Sciences

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It was Determined the current persistence components were significant in hydraulic designs of highland zone with sharp slopes. It was defined to examine the consequence of gradient, rapidity, depth and dimension of coarseness on the manning coarseness factor in this superficial river area. This is an investigational education about manning coarseness defined for highland zones protected by elements in three diverse dimensions and three slopes for dissimilar hydraulic situations in a flume of 8.3 m long, 0.8 m width and 0.5 m height under bed gradient of 0.0005. The current variations in contradiction of the Manning coarseness quantity were exposed, which comprises above hydraulic components considered. The herbal management, water balance are significant component drainage slope experimental. It was determined soil superficial roughness and hydraulic roughness factor are significant hydraulic resistance feature components. Exactly approximating the hydraulic roughness factor is significant to considerate instruments of drainage slope.

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Manning's roughness coefficient for ecological subsurface channel with modules

Cited by 10 publications

References 26 publications

Assessment of flow characteristics through a grassed canal

Assessment of flow characteristics through a grassed canal

Investigating the Relationship between the Manning Coefficients (n) of a Perforated Subsurface Stormwater Drainage Pipe and the Hydraulic Parameters

Impact of the Drainage Slope Experimental Study on the Manning Roughness Coefficient

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