Stage-Discharge Prediction for Converging Compound Channels with Narrow Floodplains

Naik, B.; Khatua, Kishanjit Kumar; Wright, Nick; Sleigh, Andrew

doi:10.1061/(asce)ir.1943-4774.0001184

Cited by 10 publications

(3 citation statements)

References 14 publications

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“…All the discussed models are suitable for straight compound channels having different cross-sectional geometries under uniform flow condition. However, for nonuniform flow condition, Naik et al (2017) gave a boundary shear force model which is well fitted for compound channels having converging floodplains for limited flow and geometric condition only. According to the author's knowledge, there has been a less work devoted to diverging compound channel and no suitable model has been developed for boundary shear force distribution for this type of channels.…”

Section: Development Of Boundary Shear Distribution Modelmentioning

confidence: 99%

“…Knight and Hamed (1984), Khatua et al (2012), Mohanty et al (2014), Devi et al (2017), Khuntia et al (2018) and Devi and Khatua (2020) developed models for distribution of boundary shear force for compound channels with homogeneous and non-homogeneous roughness by incorporating the momentum exchanges at junctions. For non-prismatic compound channels, Naik et al (2017) developed a relationship to estimate percentage boundary shear force carried by floodplains of a converging compound channel as a function of geometric and hydraulic parameters. However, for diverging floodplains, there is less work found on lateral boundary shear distribution as well as on percentage shear force carried by floodplains (Das et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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Boundary Shear Stress Distributions in Compound Channels Having Narrowing and Enlarging Floodplains

Devi

Das

Khuntia³

et al. 2021

River Hydraulics

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Compound channels are basically described as two stage open channels having main river and its adjoining floodplains. The momentum transfer phenomenon at the junction of main channel and floodplain is very crucial to be understood to estimate the discharge. The difference in water depth and roughness between the two zones generally causes momentum exchange at the interface. It is simple to quantify this momentum exchange for uniform flow conditions in river; however, for nonuniform flow condition the quantification is complex as the flow properties change in both longitudinal and lateral directions. Therefore, a study has been done on overbank flow with non-uniform flow condition, and stage discharge relationships are analyzed for accurate modeling. As natural rivers may have different configurations, so two different types of channels that are converging and diverging channels are considered and flow variables at different longitudinal positions are analyzed. Two discharge predicting models are developed which can be used for flow in natural rivers. These models depend on the non-dimensional forms of geometric and flow parameters and the percentage of the boundary shear forces carried by the adjacent floodplains. So it is required to analyze and estimate the boundary shear force distribution carried by main channel and non-prismatic floodplains before predicting flow. So, two different equations are proposed for percentage shear carried by converging and diverging floodplains. In addition, the developed models give simple ways for the quantification of percentage boundary shear force and provide accurate discharge result through non-prismatic channels. The predictions of the models are then compared with the

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Section: Development Of Boundary Shear Distribution Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Boundary Shear Stress Distributions in Compound Channels Having Narrowing and Enlarging Floodplains

Devi

Das

Khuntia³

et al. 2021

River Hydraulics

View full text Add to dashboard Cite

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“…In converging compound channels, exchange of mass and momentum between the floodplain and the main channel are increased (Bousmar, Wilkin, Jacquemart, & Zech, 2004; Rezaei, 2006). Naik, Khatua, Wright, and Sleigh (2017) developed new equations to predict boundary shear stress distribution for a converging compound channel with narrowing floodplains. Using these expressions, the stage–discharge relationships for both prismatic and converging non‐prismatic compound channels of lower width ratios may be estimated.…”

Section: Introductionmentioning

confidence: 99%

Turbulent flow structure in a vegetated non‐prismatic compound channel

Mehrabani

Mohammadi

Ayyoubzadeh

et al. 2020

River Research & Apps

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The presence of vegetation on the floodplains of compound channels affects the structure of mean flow, increases flow resistance and turbulence intensity, and impacts sediment transport. In prismatic compound channels, the shear stress at the interface between the flows in the main channel and lateral floodplains has a strong influence in the cross sectional velocity distribution and thus conveyance of the channel. Due to mass transfer between subsections, these effects are enhanced in non‐prismatic channels. In the present study, the three‐dimensional turbulent flow structure in a vegetated non‐prismatic convergent compound channel is experimentally investigated. The main purpose is to clarify the explicit influence of the combination of two factors (floodplain vegetation and convergent floodplains) on mean flow and large‐scale turbulence. The experiments were conducted for relative depths (i.e., the ratio between floodplain and main channel flow depths) equal to 0.21 and 0.31 and floodplain convergence angles equal to 7.25° and 11.3°. The results obtained in straight compound channel with vegetated floodplains were used as a reference. The analysis of the Acoustic Doppler Velocimeter measurements shows that due to convergent floodplains, a transverse current is directed from the floodplains to the main channel from both sides, generating two helical secondary currents. Investigations of the vegetation influence on Reynolds stresses shows that there is a significant vertical and lateral spreading of the shear region towards the main channel side slope. As the convergence angle increases, the floodplain flow proportion decreases. In this case, the presence of vegetation in the floodplain leads to a suppression of the momentum exchange between main channel and floodplains causing the discharge distribution between sub‐sections to be significantly different from what would be without floodplain vegetation.

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