Modeling the formation and migration of sand waves: The role of tidal forcing, sediment size and bed slope effects

Zhenlu Wang, Bingchen Liang, Guoxiang Wu, B.w. Borsje

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Tidal sand waves are rhythmic bedforms existing widely in shallow shelf seas and are formed by the interaction of tidal currents and topography. Using a process-based numerical model, Delft3D, the wave lengths and migration rates of sand waves were simulated and verified with field measurements. The physical mechanism that controls the evolution of sand waves was mainly the balance between bedload transport, suspended load transport and the slope effect. It was found that the bedload transport multiplier, which reflects the bed slope effect, was a key parameter to reproduce the observed sand wave dynamics accurately. If the bedload transport multiplier is tuned with the actual grain size, it fits the observations on wavelength of sand wave much better. Both the migration rates and wavelengths were better predicted by the process-based numerical Delft3D model compared to a linear stability analysis sand wave model, since the former adopted sophisticated process formulations necessary for accurate field predictions. Next, sand wave formation and evolution under different environment settings, including tidal forcing and sediment sizes, were examined systematically. It was found that the preferred wavelength (L FGM, fastest growing mode) of the sand wave increased with increasing tidal current magnitudes and decreasing sand diameters. Sand waves were only formed within a certain range and combination of tidal current magnitude and sand diameters. Downstream- and upstream-migration of sand waves were predicted by considering residual currents or tidal constituent of higher harmonics.

Original languageEnglish
Article number103986
JournalContinental shelf research
Volume190
Early online date13 Oct 2019
DOIs
Publication statusE-pub ahead of print/First online - 13 Oct 2019

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sand wave
sand
sediments
sediment
modeling
bedload
tidal current
wavelengths
wavelength
tides
multipliers
effect
tidal constituent
suspended load
shelf sea
bedform
stability analysis
grain size
topography

Cite this

@article{e68ebd05b33e464bad6e77ce3bcb85b7,
title = "Modeling the formation and migration of sand waves: The role of tidal forcing, sediment size and bed slope effects",
abstract = "Tidal sand waves are rhythmic bedforms existing widely in shallow shelf seas and are formed by the interaction of tidal currents and topography. Using a process-based numerical model, Delft3D, the wave lengths and migration rates of sand waves were simulated and verified with field measurements. The physical mechanism that controls the evolution of sand waves was mainly the balance between bedload transport, suspended load transport and the slope effect. It was found that the bedload transport multiplier, which reflects the bed slope effect, was a key parameter to reproduce the observed sand wave dynamics accurately. If the bedload transport multiplier is tuned with the actual grain size, it fits the observations on wavelength of sand wave much better. Both the migration rates and wavelengths were better predicted by the process-based numerical Delft3D model compared to a linear stability analysis sand wave model, since the former adopted sophisticated process formulations necessary for accurate field predictions. Next, sand wave formation and evolution under different environment settings, including tidal forcing and sediment sizes, were examined systematically. It was found that the preferred wavelength (L FGM, fastest growing mode) of the sand wave increased with increasing tidal current magnitudes and decreasing sand diameters. Sand waves were only formed within a certain range and combination of tidal current magnitude and sand diameters. Downstream- and upstream-migration of sand waves were predicted by considering residual currents or tidal constituent of higher harmonics.",
author = "Zhenlu Wang and Bingchen Liang and Guoxiang Wu and B.w. Borsje",
year = "2019",
month = "10",
day = "13",
doi = "10.1016/j.csr.2019.103986",
language = "English",
volume = "190",
journal = "Continental shelf research",
issn = "0278-4343",
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}

Modeling the formation and migration of sand waves : The role of tidal forcing, sediment size and bed slope effects. / Wang, Zhenlu; Liang, Bingchen; Wu, Guoxiang; Borsje, B.w.

In: Continental shelf research, Vol. 190, 103986, 15.11.2019.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Modeling the formation and migration of sand waves

T2 - The role of tidal forcing, sediment size and bed slope effects

AU - Wang, Zhenlu

AU - Liang, Bingchen

AU - Wu, Guoxiang

AU - Borsje, B.w.

PY - 2019/10/13

Y1 - 2019/10/13

N2 - Tidal sand waves are rhythmic bedforms existing widely in shallow shelf seas and are formed by the interaction of tidal currents and topography. Using a process-based numerical model, Delft3D, the wave lengths and migration rates of sand waves were simulated and verified with field measurements. The physical mechanism that controls the evolution of sand waves was mainly the balance between bedload transport, suspended load transport and the slope effect. It was found that the bedload transport multiplier, which reflects the bed slope effect, was a key parameter to reproduce the observed sand wave dynamics accurately. If the bedload transport multiplier is tuned with the actual grain size, it fits the observations on wavelength of sand wave much better. Both the migration rates and wavelengths were better predicted by the process-based numerical Delft3D model compared to a linear stability analysis sand wave model, since the former adopted sophisticated process formulations necessary for accurate field predictions. Next, sand wave formation and evolution under different environment settings, including tidal forcing and sediment sizes, were examined systematically. It was found that the preferred wavelength (L FGM, fastest growing mode) of the sand wave increased with increasing tidal current magnitudes and decreasing sand diameters. Sand waves were only formed within a certain range and combination of tidal current magnitude and sand diameters. Downstream- and upstream-migration of sand waves were predicted by considering residual currents or tidal constituent of higher harmonics.

AB - Tidal sand waves are rhythmic bedforms existing widely in shallow shelf seas and are formed by the interaction of tidal currents and topography. Using a process-based numerical model, Delft3D, the wave lengths and migration rates of sand waves were simulated and verified with field measurements. The physical mechanism that controls the evolution of sand waves was mainly the balance between bedload transport, suspended load transport and the slope effect. It was found that the bedload transport multiplier, which reflects the bed slope effect, was a key parameter to reproduce the observed sand wave dynamics accurately. If the bedload transport multiplier is tuned with the actual grain size, it fits the observations on wavelength of sand wave much better. Both the migration rates and wavelengths were better predicted by the process-based numerical Delft3D model compared to a linear stability analysis sand wave model, since the former adopted sophisticated process formulations necessary for accurate field predictions. Next, sand wave formation and evolution under different environment settings, including tidal forcing and sediment sizes, were examined systematically. It was found that the preferred wavelength (L FGM, fastest growing mode) of the sand wave increased with increasing tidal current magnitudes and decreasing sand diameters. Sand waves were only formed within a certain range and combination of tidal current magnitude and sand diameters. Downstream- and upstream-migration of sand waves were predicted by considering residual currents or tidal constituent of higher harmonics.

U2 - 10.1016/j.csr.2019.103986

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M3 - Article

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