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On the stability of river bifurcations created by longitudinal training walls : Numerical investigation. / Le, Binh; Crosato, Alessandra; Mosselman, Erik; Uijttewaal, Wim.

In: Advances in Water Resources, Vol. 113, 2018, p. 112-125.

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@article{de908013d5954ba2bef98e3428c7705f,
title = "On the stability of river bifurcations created by longitudinal training walls: Numerical investigation",
abstract = "To maintain a navigable channel and improve high-flow conveyance, engineers have recently proposed constructing longitudinal training walls as an alternative to the traditional transverse groynes. However, previous work has shown that the system of parallel channels created by a longitudinal training wall might be unstable in rivers with alternate bars. Many questions remain unanswered, particularly whether a stable system can be obtained by carefully designing the bifurcation point. This work analyses the stability of the bifurcating system created by a thin longitudinal wall in sand-bed rivers with alternate bars or point bars. The methodology includes performing 102 numerical tests using the Delft3D code to reproduce an idealized low-land river, either straight or meandering. The results show that the system of parallel channels separated by a training wall may indeed become unstable. An important factor is found to be the location of the bifurcation point with respect to a neighboring bar or point bar. The same trends are observed for both constant and variable discharge, in straight and meandering channels. The results suggest that cyclic growth and decline of the bifurcating channels may arise as inherent system behavior, without the need of any additional external forcing. We explain this from changes in the relationship between sediment transport ratio and discharge ratio as the bifurcation evolves. This cyclic behavior can be regarded as a form of system stability and can be obtained by carefully placing the starting point of the longitudinal training wall, and thus the bifurcation point, near the top of a bar.",
keywords = "Longitudinal training wall, River morphology, River bars, Bifurcation, Channel stability, Delft3D",
author = "Binh Le and Alessandra Crosato and Erik Mosselman and Wim Uijttewaal",
year = "2018",
doi = "10.1016/j.advwatres.2018.01.012",
language = "English",
volume = "113",
pages = "112--125",
journal = "Advances in Water Resources",
issn = "0309-1708",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - On the stability of river bifurcations created by longitudinal training walls

T2 - Advances in Water Resources

AU - Le, Binh

AU - Crosato, Alessandra

AU - Mosselman, Erik

AU - Uijttewaal, Wim

PY - 2018

Y1 - 2018

N2 - To maintain a navigable channel and improve high-flow conveyance, engineers have recently proposed constructing longitudinal training walls as an alternative to the traditional transverse groynes. However, previous work has shown that the system of parallel channels created by a longitudinal training wall might be unstable in rivers with alternate bars. Many questions remain unanswered, particularly whether a stable system can be obtained by carefully designing the bifurcation point. This work analyses the stability of the bifurcating system created by a thin longitudinal wall in sand-bed rivers with alternate bars or point bars. The methodology includes performing 102 numerical tests using the Delft3D code to reproduce an idealized low-land river, either straight or meandering. The results show that the system of parallel channels separated by a training wall may indeed become unstable. An important factor is found to be the location of the bifurcation point with respect to a neighboring bar or point bar. The same trends are observed for both constant and variable discharge, in straight and meandering channels. The results suggest that cyclic growth and decline of the bifurcating channels may arise as inherent system behavior, without the need of any additional external forcing. We explain this from changes in the relationship between sediment transport ratio and discharge ratio as the bifurcation evolves. This cyclic behavior can be regarded as a form of system stability and can be obtained by carefully placing the starting point of the longitudinal training wall, and thus the bifurcation point, near the top of a bar.

AB - To maintain a navigable channel and improve high-flow conveyance, engineers have recently proposed constructing longitudinal training walls as an alternative to the traditional transverse groynes. However, previous work has shown that the system of parallel channels created by a longitudinal training wall might be unstable in rivers with alternate bars. Many questions remain unanswered, particularly whether a stable system can be obtained by carefully designing the bifurcation point. This work analyses the stability of the bifurcating system created by a thin longitudinal wall in sand-bed rivers with alternate bars or point bars. The methodology includes performing 102 numerical tests using the Delft3D code to reproduce an idealized low-land river, either straight or meandering. The results show that the system of parallel channels separated by a training wall may indeed become unstable. An important factor is found to be the location of the bifurcation point with respect to a neighboring bar or point bar. The same trends are observed for both constant and variable discharge, in straight and meandering channels. The results suggest that cyclic growth and decline of the bifurcating channels may arise as inherent system behavior, without the need of any additional external forcing. We explain this from changes in the relationship between sediment transport ratio and discharge ratio as the bifurcation evolves. This cyclic behavior can be regarded as a form of system stability and can be obtained by carefully placing the starting point of the longitudinal training wall, and thus the bifurcation point, near the top of a bar.

KW - Longitudinal training wall

KW - River morphology

KW - River bars

KW - Bifurcation

KW - Channel stability

KW - Delft3D

UR - http://resolver.tudelft.nl/uuid:de908013-d595-4ba2-bef9-8e3428c7705f

U2 - 10.1016/j.advwatres.2018.01.012

DO - 10.1016/j.advwatres.2018.01.012

M3 - Article

VL - 113

SP - 112

EP - 125

JO - Advances in Water Resources

JF - Advances in Water Resources

SN - 0309-1708

ER -

ID: 36909724