Mean sediment residence time in barchan dunes - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Article Dans Une Revue Journal of Geophysical Research: Earth Surface Année : 2014

Mean sediment residence time in barchan dunes

D. Zhang
  • Fonction : Auteur
X. Yang
  • Fonction : Auteur

Résumé

When a barchan dune migrates, the sediment trapped on its lee side is later mobilized when exposed on the stoss side. Then sand grains may undergo many dune turnover cycles before their ejection along the horns, but the amount of time a sand grain contributes to the dune morphodynamics remains unknown. To estimate such a residence time, we analyze sediment particle motions in steady state barchans by tracking individual cells of a 3-D cellular automaton dune model. The overall sediment flux may be decomposed into advective and dispersive fluxes to estimate the relative contribution of the underlying physical processes to the barchan shape. The net lateral sediment transport from the center to the horns indicates that dispersion on the stoss slope is more efficient than the convergent sediment fluxes associated with avalanches on the lee slope. The combined effect of these two antagonistic dispersive processes restricts the lateral mixing of sediment particles in the central region of barchans. Then, for different flow strengths and dune sizes, we find that the mean residence time of sediment particles in barchans is equal to the surface of the central longitudinal dune slices divided by the input sand flux. We infer that this central slice contains most of the relevant information about barchan morphodynamics. Finally, we initiate a discussion about sediment transport and memory in the presence of bed forms using the advantages of the particle tracking technique.
Fichier principal
Vignette du fichier
JGR Earth Surface - 2014 - Zhang - Mean sediment residence time in barchan dunes.pdf (1.71 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

insu-03581140 , version 1 (19-02-2022)

Licence

Copyright (Tous droits réservés)

Identifiants

Citer

D. Zhang, X. Yang, O. Rozier, C. Narteau. Mean sediment residence time in barchan dunes. Journal of Geophysical Research: Earth Surface, 2014, 119, pp.451-463. ⟨10.1002/2013JF002833⟩. ⟨insu-03581140⟩
35 Consultations
40 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More