Suspended sediment transport around a large-scale laboratory breaker bar - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Coastal Engineering Année : 2017

Suspended sediment transport around a large-scale laboratory breaker bar

Résumé

This paper presents novel insights into suspended sediment concentrations and fluxes under a large-scale laboratory plunging wave. Measurements of sediment concentrations and velocities were taken at 12 locations around an evolving breaker bar, covering the complete breaking region from shoaling to inner surf zone, with particular high resolution near the bed using an Acoustic Concentration and Velocity Profiler. Wave breaking evidently affects sediment pick-up rates, which increase by an order of magnitude from shoaling to breaking zone. Time-averaged reference concentrations correlate poorly with periodic and time-averaged near-bed velocities, but correlate significantly with near-bed time-averaged turbulent kinetic energy. The net depth-integrated suspended transport is offshore-directed and primarily attributed to current-related fluxes (undertow) at outer-flow elevations (i.e. above the wave bottom boundary layer). The wave-related suspended transport is onshore-directed and is generally confined to the wave bottom boundary layer. Cross-shore gradients of sediment fluxes are quantified to explain spatial patterns of sediment pick-up and deposition and of cross-shore sediment advection. Suspended particles travel back and forth between the breaking and shoaling zones following the orbital motion, leading to local intra-wave concentration changes. At locations between the breaker bar crest and bar trough, intra-wave concentration changes are due to a combination of horizontal advection and of vertical exchange with the bedload layer: sediment is entrained in the bar trough during the wave trough phase, almost instantly advected offshore, and deposited near the bar crest during the wave crest phase. Finally, these results are used to suggest improvements for suspended sediment transport models.
Fichier principal
Vignette du fichier
VanderZandenEtal_SuspensionCE2017_1.pdf (2.66 Mo) Télécharger le fichier
Origine : Accord explicite pour ce dépôt

Dates et versions

hal-01660537 , version 1 (29-09-2021)

Identifiants

Citer

Joep van Der Zanden, Dominic A. van Der A, David Hurther, Iván Cáceres, Tom O’donoghue, et al.. Suspended sediment transport around a large-scale laboratory breaker bar. Coastal Engineering, 2017, 125, pp.51 - 69. ⟨10.1016/j.coastaleng.2017.03.007⟩. ⟨hal-01660537⟩

Collections

UGA CNRS OSUG LEGI
158 Consultations
88 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More