Special Issue "Sediment Transport, Local Scour, and Fluvial Hydraulics"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water Erosion and Sediment Transport".

Deadline for manuscript submissions: closed (30 August 2021) | Viewed by 3958

Special Issue Editor

Dr. Jueyi Sui
E-Mail Website
Guest Editor
School of Engineering, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
Interests: local scour; sediment transport; river ice hydrology; fluvial hydraulics; vegetated channel; snow hydrology
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Special Issue Information

Dear Colleagues,

To date, scientists have conducted a large amount of cutting-edge research on all aspects of sediment transport and fluvial hydraulics interpreted in its widest sense. So many research papers and books have been published to help researchers to continue to explore the subject in the right direction. The aim of this Special Issue is to seek research works that improve knowledge of sediment transport, local scour, and fluvial process. It will include not only the mechanics of sediment transport in natural rivers and laboratory flumes, but also what is related to local scour and fluvial processes under both open channel and ice-covered flow conditions. Research work regarding environmental and ecological impacts of sedimentation, interaction between river ice and riverbed deformation, as well as the effect of reservoir sedimentation and coastal erosion will also be included.

Dr. Jueyi Sui
Guest Editor

Manuscript Submission Information

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Keywords

  • erosion
  • fluvial hydraulics
  • hydraulic modeling
  • local scour
  • reservoir sedimentation
  • river ice hydraulics
  • sediment transport

Published Papers (5 papers)

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Research

Article
Characteristics of Turbulence in the Downstream Region of a Vegetation Patch
Water 2021, 13(23), 3468; https://doi.org/10.3390/w13233468 - 06 Dec 2021
Cited by 3 | Viewed by 581
Abstract
In presence of vegetation patches in a channel bed, different flow–morphology interactions in the river will result. The investigation of the nature and intensity of these structures is a crucial part of the research works of river engineering. In this experimental study, the [...] Read more.
In presence of vegetation patches in a channel bed, different flow–morphology interactions in the river will result. The investigation of the nature and intensity of these structures is a crucial part of the research works of river engineering. In this experimental study, the characteristics of turbulence in the non-developed region downstream of a vegetation patch suffering from a gradual fade have been investigated. The changes in turbulent structure were tracked in sequential patterns by reducing the patch size. The model vegetation was selected carefully to simulate the aquatic vegetation patches in natural rivers. Velocity profile, TKE (Turbulent Kinetic Energy), turbulent power spectra and quadrant analysis have been used to investigate the behavior and intensity of the turbulent structures. The results of the velocity profile and TKE indicate that there are three different flow layers in the region downstream of the vegetation patch, including the wake layer, mixing layer and shear layer. When the vegetation patch is wide enough (Dv/Dc > 0.5, termed as the patch width ratio, where Dv is the width of a vegetation patch and Dc is the width of the channel), highly intermittent anisotropic turbulent events appear in the mixing layer at the depth of z/Hv = 0.7~1.1 and distance of x/Hv = 8~12 (where x is streamwise distance from the patch edge, z is vertical distance from channel bed and Hv is the height of a vegetation patch). The results of quadrant analysis show that these structures are associated with the dominance of the outward interactions (Q1). Moreover, these structures accompany large coherent Reynolds shear stresses, anomalies in streamwise velocity, increases in the standard deviation of TKE and increases in intermittent Turbulent Kinetic Energy (TKEi). The intensity and extents of these structures fade with the decrease in the size of a vegetation patch. On the other hand, as the size of the vegetation patch decreases, von Karman vortexes appear in the wake layer and form the dominant flow structures in the downstream region of a vegetation patch. Full article
(This article belongs to the Special Issue Sediment Transport, Local Scour, and Fluvial Hydraulics)
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Article
Investigation of the Effect of Vegetation on Flow Structures and Turbulence Anisotropy around Semi-Elliptical Abutment
Water 2021, 13(21), 3108; https://doi.org/10.3390/w13213108 - 04 Nov 2021
Cited by 2 | Viewed by 559
Abstract
In the present experimental study, the effect of vegetation on flow structure and scour profile around a bridge abutment has been investigated. The vegetation in the channel bed significantly impacted the turbulent statistics and turbulence anisotropy. Interestingly, compared to the channel without vegetation, [...] Read more.
In the present experimental study, the effect of vegetation on flow structure and scour profile around a bridge abutment has been investigated. The vegetation in the channel bed significantly impacted the turbulent statistics and turbulence anisotropy. Interestingly, compared to the channel without vegetation, the presence of vegetation in the channel bed dramatically reduced the primary vortex, but less impacts the wake vortex. Moreover, the tangential and radial velocities decreased with the vegetation in the channel bed, while the vertical velocity (azimuthal angle > 90°) had large positive values near the scour hole bed. Results showed that the presence of the vegetation in the channel bed caused a noticeable decrease in the Reynolds shear stress. Analysis of the Reynolds stress anisotropy indicated that the flow had more tendency to be isotropic for the vegetated bed. Results have shown that the anisotropy profile changes from pancake-shaped to cigar-shaped in the un-vegetated channel. In contrast, it had the opposite reaction for the vegetated bed. Full article
(This article belongs to the Special Issue Sediment Transport, Local Scour, and Fluvial Hydraulics)
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Article
Formation of Coherent Flow Structures beyond Vegetation Patches in Channel
Water 2021, 13(20), 2812; https://doi.org/10.3390/w13202812 - 10 Oct 2021
Cited by 5 | Viewed by 561
Abstract
By using model vegetation (e.g., synthetic bars), vortex structures in a channel with vegetation patches have been studied. It has been reported that vortex structures, including both the vertical and horizontal vortexes, may be produced in the wake in the channel bed with [...] Read more.
By using model vegetation (e.g., synthetic bars), vortex structures in a channel with vegetation patches have been studied. It has been reported that vortex structures, including both the vertical and horizontal vortexes, may be produced in the wake in the channel bed with a finite-width vegetation patch. In the present experimental study, both velocity and TKE have been measured (via Acoustic Doppler Velocimeter—ADV) to study the formation of vortexes behind four vegetation patches in the channel bed. These vegetation patches have different dimensions, from the channel-bed fully covered patch to small-sized patches. Model vegetation used in this research is closely similar to vegetation in natural rivers with a gravel bed. The results show that, for a channel with a small patch (Lv/Dc = 0.44 and Dv/Dc = 0.33; where Lv and Dv are the length and width of patch and Dc is the channel width, respectively), both the flow passing through the patch and side flow around the patch have a considerable effect on the formation of flow structures beyond the patch. The results of further analysis via 3D classes of the bursting events show that the von Karman vortex street splits into two parts beyond the vegetation patch as the strong part near the surface and the weak part near the bed; while the middle part of the flow is completely occupied by the vertical vortex formed at a distance of 0.8–1 Hv beyond the vegetation patch, and thus, the horizontal vortexes cannot be detected in this region. The octant analysis is conducted for the coherent shear stress analysis that confirms the results of this experimental study. Full article
(This article belongs to the Special Issue Sediment Transport, Local Scour, and Fluvial Hydraulics)
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Article
A Numerical Study of the Flow and Sediment Interaction in the Middle Reach of the Huai River
Water 2021, 13(15), 2041; https://doi.org/10.3390/w13152041 - 27 Jul 2021
Viewed by 596
Abstract
In recent years, the incoming sediments from upstream of the Huai River have continuously decreased. The relationship between flow and sediment has significantly changed. Therefore, the erosion and deposition characteristics of the river could be affected. To investigate this interaction between flow and [...] Read more.
In recent years, the incoming sediments from upstream of the Huai River have continuously decreased. The relationship between flow and sediment has significantly changed. Therefore, the erosion and deposition characteristics of the river could be affected. To investigate this interaction between flow and sediment, the present study was conducted using the Wanglin section in the middle reach of the Huai River as the study site. A 1D hydrodynamic model was developed and validated using field data. Data from 1985–2014 were used as a continuous series while data from 2004–2014 were used as a repetitive series. The sediment variation and distribution processes at different locations were discussed. It was found that the river channel displayed several notable characteristics. In the flow direction, the channel had frontal erosion and backward deposition. The variation rate was relatively slow. With reduced sediment, the overall deposition at the Wanglin section was significantly mitigated. Future recommendations are provided based on the present simulation for flood mitigation along the Huai River. Full article
(This article belongs to the Special Issue Sediment Transport, Local Scour, and Fluvial Hydraulics)
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Article
Assessment of Critical Shear Stress and Threshold Velocity in Shallow Flow with Sand Particles
Water 2021, 13(7), 994; https://doi.org/10.3390/w13070994 - 04 Apr 2021
Cited by 7 | Viewed by 970
Abstract
In this study, the incipient motion of four groups of sand, ranging from medium to very coarse particles, was experimentally examined using an acoustic Doppler velocimeter (ADV) in different water depths under the hydraulically transitional flow condition. The transport criterion of the Kramer [...] Read more.
In this study, the incipient motion of four groups of sand, ranging from medium to very coarse particles, was experimentally examined using an acoustic Doppler velocimeter (ADV) in different water depths under the hydraulically transitional flow condition. The transport criterion of the Kramer visual observation method was used to determine threshold conditions. Some equations for calculating threshold average and near-bed velocities were derived. Results showed that the threshold velocity was directly proportional to both sediment particle size and water depth. The vertical distributions of the Reynolds shear stress showed an increase from the bed to about 0.1 of the water’s depth, after performing a damping area, then a decrease toward the water surface. By extending the linear portion of the Reynolds shear stress in the upper zone of the damping area to the bed, the critical shear stress, particle shear Reynolds number, and critical Shields parameter were calculated. Results showed that the critical Shields parameter was located under the Shields curve, showing no sediment motion. This indicates that the incipient motion of sediment particles occurred with smaller bed shear stress than that estimated using the Shields diagram in the hydraulically transitional flow region. The reason could be related to differences between the features of the present experiment and those of the experiments used in the development of the Shields diagram, including the approaches to determine and define threshold conditions, the accuracy of experimental tools to estimate critical shear stress, and sediment particle characteristics. Therefore, the change in the specifications of experiments from those on which the Shields diagram has been based led to the deviation between the estimation using the Shields diagram and that of real threshold conditions, at least in the hydraulically transitional flow region with sand particles. Full article
(This article belongs to the Special Issue Sediment Transport, Local Scour, and Fluvial Hydraulics)
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