Experimental study on the influence of river flow confluences on the open channel stage–discharge relationship

Wang, Xiekang; Yan, Xu‐Feng; Duan, Huan‐Feng; Liu, Xingnian; Huang, Er

doi:10.1080/02626667.2019.1661415

Cited by 27 publications

(13 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…9a, b that the velocity profiles in line 1 are in the flow deflection zone with lower velocity values in comparison with lines 2-4. This trend in velocity profiles is similar to the results of Wang et al (2019). It should be noted that due to the mixing of the flow and bed topography caused by bedload (Fig.…”

Section: Time Average Velocity Profilessupporting

confidence: 87%

See 1 more Smart Citation

Experimental investigation of flow pattern over a fully developed bed at a 60° river confluence in large floods

et al. 2022

View full text Add to dashboard Cite

River confluences have a complex flow and sedimentation pattern that have vital influences on the hydraulic and bed morphology of river reach and the surrounding area. Confluences can be observed in waterways with various situations such as live bed conditions. This condition is a hydro-morphological situation with a high densimetric Froude number, i.e., bed load transport is supplied from upstream. According to the literature review, most of the experimental studies investigate the flow pattern on the flatbed and not on the developed riverbed, or/and in the low densimetric Froude number, or/and without supplying the sediment from upstream. Therefore, in the present study for the quantification of the flow pattern under these conditions, each developed bed was fixed with the cement blanket method in the laboratory. Then, the 3D velocity was measured at specific points at the confluence. The current study was designed to understand the flow pattern corresponding to the river bed behavior in the case of large floods. It is expected that the morphological features downstream of the confluence have a different pattern than the ones in the condition described in other literature. Thus, this paper describes briefly what are the different bed features and investigates the corresponding flow pattern. The results of the flow pattern on the developed bed show that all zones at the river confluence can be observed except the point bar due to the approximate equality of the mean longitudinal velocity of the separation zone and the main channel upstream of the confluence. Moreover, results show that by increasing the bedload ratio (sediment discharge to water discharge of the main channel of upstream of the confluence) from 0 to 3 × 10−4, flow deflection to the outer bank of the channel decreased down to 45%, the stagnation equivalent area decreased down to 2.5 times, and bed shear stress decreased down to 40%. Hence, the momentum of lateral flow decreased with increasing bedload. Besides, the recovery zone occurred at a longer distance after the confluence compared to the case without bedload. Hence, the location of the maximum velocity zone, vortices, and secondary flows changed downstream of the confluence, by changing the bed load value.

show abstract

Section: Time Average Velocity Profilessupporting

confidence: 87%

“…Recently, Wang et al (2019) evaluated the stage-discharge relationship at a channel confluence and a scaled model of a river confluence in China. They showed that the water level at the main channel increased due to the tributary channel flow.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of flow pattern over a fully developed bed at a 60° river confluence in large floods

et al. 2022

View full text Add to dashboard Cite

show abstract

“…In addition, the area of the stagnation zone at the upstream corner of the tributary channel with the main channel increases with decreasing the W*. It is caused by the effect of the higher downward velocity from the narrower tributary channel, which causes a higher upstream water level or backwater effect [21]. It is similar to increases in the tributary channel discharge in studies such as ref.…”

Section: Longitudinal Velocity Distribution and Flow Patternsmentioning

confidence: 57%

“…It is observed that the maximum value of the V velocity takes place at the downstream corner of the tributary channel with the main channel and its value and gradient increases as the tributary width decreases.In addition, the area of the stagnation zone at the upstream corner of the tributary channel with the main channel increases with decreasing the W*. It is caused by the effect of the higher downward velocity from the narrower tributary channel, which causes a higher upstream water level or backwater effect[21]. It is similar to increases in the tributary channel discharge in studies such as ref [2].…”

mentioning

confidence: 69%

Tributary Channel Width Effect on the Flow Behavior in Trapezoidal and Rectangular Channel Confluences

Azma

Zhang

2020

Processes

View full text Add to dashboard Cite

Channel confluences happen commonly in water transport networks and natural rivers. Utilizing a 3D CFD code, a series of numerical simulations were performed using a large eddy simulation turbulence model to investigate the effect of the variations in tributary channel width and the transverse geometrical shape of the main channel on the flow parameters and vertical structure in a T-shape confluence. The code was calibrated using the experimental data from the literature. Flow parameters were considered in ratios of tributary width to the main channel width in trapezoidal and rectangular channels. Results indicate that decreasing the width ratio of the tributary channel to the main channel significantly affects the flow structure in the confluence. Generally, it increases the width and length of the main recirculation zone. It also increases the maximum velocity near the bed, especially in cases with a trapezoidal shape. Besides, it highly affects the structure and formation of the recirculation zone in trapezoidal channels.

show abstract

“…Understanding the fluvial process in the mountain river confluence is beneficial for natural hazard assessments (Badoux et al, 2014) and river restoration (Guillén‐Ludeña et al, 2016). Different from a lower‐gradient river confluence, a mountain river confluence is commonly identified with the low discharge ratio of the tributary to the main channel, sediment source largely fed by the tributary and discharge fed by the main channel, a wide range of sediment size leading to bed armouring, and large bed slope difference between the tributary and main channel (Canelas et al, 2020; Guillén‐Ludeña et al, 2016; Leite Ribeiro et al, 2012; Wang et al, 2019). Due to the marked hydro‐morphological features, mountain river confluences show distinct behaviours compared with plain river confluences.…”

Section: Introductionmentioning

confidence: 99%

Numerical assessments of bed morphological evolution in mountain river confluences under effects of hydro‐morphological factors

Yan

Duan

Yang

et al. 2022

Hydrological Processes

Self Cite

View full text Add to dashboard Cite

Understanding hydro‐morphological characteristics in mountain river confluences is significant in flood disaster mitigation and mountain river restoration, which is still poorly explored. This study employed a 2D hydro‐morphological model based on the finite element method to simulate the major bed morphological features in a mountainous‐type flume confluence and evaluate the effects of main controlling factors on these features. The modelling results show that the dominant bed morphological features in mountain river confluences can be well produced by the 2D model. Five controlling factors including downstream water level (H), branch discharge ratio (Qr), main channel sediment supply ratio (ψ), tributary slope (St) and confluence angle (α) reflecting different flow‐sediment‐geometry scenarios were adopted into a sensitive study. The upstream reach of the main channel is controlled by H and ψ and their decreases lead to bed degradation. The increase in Qr, St, and α mainly results in bed aggradation and steepening in the tributary, attaining a higher sediment transport rate. This contrasts the existing experimental results, due to the difference in sediment feeding. The size of the bank‐attached bar is promoted by the increase in Qr, St, and α and the decrease in H and ψ. A quantitative analysis shows that the water surface slope well correlates with various dimensions of the scour hole and bar morphology (correlation = 0.58–0.8). Meanwhile, the bank‐attached bar displays a strong self‐similarity (correlation = 0.84–0.98) regarding its geometric dimensions. This study provides new insights into the existing knowledge of the hydro‐sediment‐morphodynamics of mountain river confluences obtained from laboratory studies and field investigations.

show abstract

Experimental study on the influence of river flow confluences on the open channel stage–discharge relationship

Cited by 27 publications

References 31 publications

Experimental investigation of flow pattern over a fully developed bed at a 60° river confluence in large floods

Experimental investigation of flow pattern over a fully developed bed at a 60° river confluence in large floods

Tributary Channel Width Effect on the Flow Behavior in Trapezoidal and Rectangular Channel Confluences

Numerical assessments of bed morphological evolution in mountain river confluences under effects of hydro‐morphological factors

Contact Info

Product

Resources

About