Effect of Roughness on Discharge

Lau, Thomas; Afshar, Nasser Rostam

doi:10.33736/jcest.124.2013

Cited by 10 publications

(7 citation statements)

References 2 publications

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“…The relationship between the velocity and the Manning roughness coefficient, showed that the velocity was inversely proportional with the Mannings' coefficient. This agrees with (Lau and Afshar, 2013;Gualtieri et al, 2018) from their work which showed that flow rate decreased as the Manning's coefficient increased. This is because smoother surfaces have lower roughness coefficient and less retarding effect on the water flow, hence a higher rate is produced and it can be concluded that flow rate and roughness coefficient were influenced by bed roughness and slope.…”

Section: Effects Of the Soil Boundary Influence On The Velocity Of Flow For Both Riverssupporting

confidence: 91%

“…This shows that there is a great relationship between the Velocity and Mannings' Coefficient at all sampling points of both rivers if the geometry of the river channel is kept constant. Manning's coefficient represents the resistance to flood flows in channels and flood plains (Lau and Afshar, 2013). This means the higher the manning's coefficient, the greater the resistance to flooding indicating that the tendency of flooding is highest at Fiwasaye point and Omu-Aran because of the lowest values of Manning's coefficient on the aforementioned points on both rivers.…”

Section: Effects Of the Soil Boundary Influence On The Velocity Of Flow For Both Riversmentioning

confidence: 99%

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Boundary Influence and Flow Characteristics of Orisa and Ala Rivers in Kwara and Ondo States, Nigeria

Elemile

Folorunso

2021

LAUJOCES

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In this study, the effects of boundary influence on flow characteristics of Rivers Ala and Orisa were investigated. Soil samples were collected from three points each from both rivers namely Glory Parish Area (GPA), Olusola Oke Area (OOA) and Fiwasaye; Aran-Orin Area (AOA), Rore and Omu-Aran on Rivers Ala and Orisa Respectively. A MGG/KL-DCB Portable Electromagnetic Velocity Meter was used to measure the in-situ readings of discharge and velocity at the various points. The sediments collected from the sampling points were placed in the Flume in the Hydraulic Laboratory of Civil Engineering Department, Landmark University. The Flume was then set with the measured parameter (Discharge) for each sampling point to apply the Flume to determine the Velocity for both Rivers at slopes of 0.008 to 0.056 respectively. The velocities obtained at the different slopes were inserted into Manning’s Coefficient equation to obtain the flow characteristics. The relationship between the velocity and Manning’s Coefficient was determined using the Spearman’s rank correlation coefficient. All analyses were done at P-value less than 0.05 level of significance. The velocity varied between 0.0237± 0.0004 and 0.0587± 0.0004 m/s; 0.0542± 0.0004 and 0.0701± 0.0003m/s and 0.0789± 0.0005 and 0.0172± 0.1323m/s for GPA, OOA and Fiwasaye for Ala River and between 0.0751± 0.0007 and 0.1008± 0.0006m/s; 0.0628± 0.0007 and 0.0839± 0.0004m/s and 0.0421± 0.0005 and 0.1076± 0.0004m/s for AOA, Rore and Omu-Aran for Orisa River. The results of the effects of soil boundary influence showed that the velocity was inversely proportional with the Mannings’ coefficient at all sampling points of both rivers if the geometry of the river channel is kept constant. This indicates that areas with high velocities are prone to flooding. Further studies should be carried out on more sampling points on the rivers to confirm flow characteristics of the rivers.

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Section: Effects Of the Soil Boundary Influence On The Velocity Of Flow For Both Riverssupporting

confidence: 91%

Section: Effects Of the Soil Boundary Influence On The Velocity Of Flow For Both Riversmentioning

confidence: 99%

Boundary Influence and Flow Characteristics of Orisa and Ala Rivers in Kwara and Ondo States, Nigeria

Elemile

Folorunso

2021

LAUJOCES

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“…We assume that the reason for the low epiphyll cover of our artificial substrates was manyfold: installation, lack of surface roughness and environment. We mounted the plastic sheets at an angle comparable to fern leaves and flexibly, which allowed for wind movement, and from their smooth surface, water runs off quickly (Lau & Afshar, 2013) and even epiphyll spores might be removed (Dean & Smith, 1978; Bentley, 1987). In two other studies from Costa Rica, rough, horizontally placed plastics were covered already by liverworts within nine months to 11.5% (Monge‐Nájera & Blanco, 1995) and were colonized within 12 months by 32 lichen species (Lücking & Bernecker‐Lücking, 2002), respectively.…”

Section: Discussionmentioning

confidence: 99%

Impact of longevity and wettability of fern leaves on epiphyll colonization in a Mexican lowland rainforest

Cerón-Carpio

García

Guerrero‐Analco

et al. 2023

J Vegetation Science

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Questions Leaf traits play an important role in the epiphyll colonization of leaves. Although ferns are common in forest understories, they have been widely ignored as possible host plants. We asked: How does epiphyll colonization (cover, richness, and composition) differ among fern species depending on their leaf longevity and surface wettability? Location Tropical Biological Station of “Los Tuxtlas”, Veracruz (Mexico). Methods Epiphyll cover was monitored on leaves of six individuals per species after 2, 5, 12, 16.5, and 26 months. Leaf longevity was calculated from leaf turnover rates over 24 months. Leaf wettability was determined through the contact angle technique. Results All studied fern species had hydrophilic leaf surfaces. Fern species with shorter leaf longevity (14.4–17.8 months) were colonized faster by epiphylls than species with longer leaf life spans (33.9–38.8 months). The area of the oldest leaves was covered to 1.2%–26.1% by foliicolous lichens and to 0.3%–2.2% by green algae. Foliicolous lichens were more species‐rich on Danaea nodosa (27 spp.) than on the other fern species (1–9 lichen spp.). Foliose liverworts thrived on the only riparian fern (3.57%). Only 0.04%–1.1% of the area of plastic substrates was colonized by epiphylls. Conclusions The hydrophilic leaf surfaces of ferns facilitated the colonization of epiphylls, especially of foliicolous lichens. The speed of epiphyll colonization was faster in ferns with shorter leaf longevity but increased in all species with leaf age. However, the relatively low epiphyll cover on fern leaves and artificial substrates in our study might be related to unfavorable microclimatic parameters.

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“…The degree of roughness depends on several factors, the most important of which in open-channel flow are surface roughness of the bed material, channel section, size and shape of channel, stage and discharge, obstruction to flow, type, density and distribution of vegetation, among others [3]. But the roughness coefficient mainly depends on the bed slope and surface roughness [4]. In general, all factors that tend to cause turbulence and retardance of flow, and hence energy losses, increase the roughness coefficient; those that cause smoother flow conditions tend to decrease the roughness coefficient [5].…”

Section: Introductionmentioning

confidence: 99%

Determination of Manning's Roughness Coefficient in Bijayapur Irrigation Canal, Kaski, Nepal

Gautam

2021

Himalayan J. Appl. Sci. Engin.

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The discharge in irrigation canal is to be determined for the proper allocation of water to the fields as per the crop-water requirement. Manning’s roughness coefficient is one of the major important parameters for estimating discharge in open channel. The purpose of this research is to determine Manning’s roughness coefficient in open channel flow by means of measuring velocity, cross-section, bed slope using Manning’s equation. It also discusses how it varies along with various aspects of channel geometry and draws useful conclusion from the analysis. The investigation was carried out in the Bijayapur Irrigation System which is situated in Kaski district of Nepal. The velocity was measured using current-meter and discharge was calculated from the area velocity methods. Roughness coefficient was calculated using the Manning’s equations for the uniform flow in open channel. The average value of Manning’s roughness coefficient at Sakneri and Bijayapur computed from this study was found 0.028 and 0.037, respectively. The roughness coefficient, however, being a parameter representing the integrated effects of the channel cross-sectional resistance, the result of this study shows the higher value of roughness coefficient for the material (cement rubble masonry) used in the construction of canal. The higher value of roughness coefficient might be due to uneven bed and poor condition of banks as observed during the study. The greater value of roughness coefficient definitely reduces discharge which leads to the tail end deprivation in the command area.

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Effect of Roughness on Discharge

Cited by 10 publications

References 2 publications

Boundary Influence and Flow Characteristics of Orisa and Ala Rivers in Kwara and Ondo States, Nigeria

Boundary Influence and Flow Characteristics of Orisa and Ala Rivers in Kwara and Ondo States, Nigeria

Impact of longevity and wettability of fern leaves on epiphyll colonization in a Mexican lowland rainforest

Determination of Manning's Roughness Coefficient in Bijayapur Irrigation Canal, Kaski, Nepal

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