TY - JOUR
T1 - Sand transport processes and bed level changes induced by two alternating laboratory swash events
AU - Van Der Zanden, Joep
AU - Cáceres, Iván
AU - Eichentopf, Sonja
AU - Ribberink, Jan S.
AU - Van Der Werf, Jebbe J.
AU - Alsina, José M.
N1 - Funding Information:
The experiments described in this publication were supported by the European Communitys Horizon 2020 Programme through the grant to the budget of the Integrated Infrastructure Initiative HYDRALAB+ , Contract no. 654110 , and was conducted as part of the transnational access project RESIST. JvdZ and JJvdW gratefully acknowledge funding by NWO-TTW (contract no. 16130 ) and SE gratefully acknowledges funding from the Department of Civil and Environmental Engineering, Imperial College London . We thank fellow RESIST researchers and the CIEMLAB staff (Oscar Galego, Andrea Marzeddu, and Joaquim Sospedra) for their contributions to the experiments. Finally, we are grateful to the two reviewers for their constructive feedback on the initial submitted manuscript.
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2019/10
Y1 - 2019/10
N2 - Sand transport processes and net transport rates are studied in a large-scale laboratory swash zone. Bichromatic waves with a phase modulation were generated, producing two continuously alternating swash events that have similar offshore wave statistics but which differ in terms of wave-swash interactions. Measured sand suspension and sheet flow dynamics show strong temporal and spatial variability, related to variations in flow velocity and locations of wave capture and wave-backwash interactions. Suspended and sheet flow layer transport rates in the lower swash zone are generally of same magnitude, but sheet flow exceeds the suspended load transport by up to a factor four during the early uprush. The bed level near the inner surf zone is relatively steady during a swash cycle, but changes of O(cm/s) are measured near the mid swash zone where wave-swash interactions lead to strongly non-uniform flows. The two alternating swash events produce a dynamic equilibrium, with bed level changes up to a few mm induced by single swash events, but with net morphodynamic change over multiple events that is two orders of magnitude lower. Most of the intra-swash and the single-event-averaged bed level changes in the swash zone are caused by a redistribution of sediment within the swash. The transport of sediment across the surf-swash boundary is minor at intra-swash time scale, but becomes increasingly significant at swash-averaged time scales or longer (i.e., averaged over multiple swash events).
AB - Sand transport processes and net transport rates are studied in a large-scale laboratory swash zone. Bichromatic waves with a phase modulation were generated, producing two continuously alternating swash events that have similar offshore wave statistics but which differ in terms of wave-swash interactions. Measured sand suspension and sheet flow dynamics show strong temporal and spatial variability, related to variations in flow velocity and locations of wave capture and wave-backwash interactions. Suspended and sheet flow layer transport rates in the lower swash zone are generally of same magnitude, but sheet flow exceeds the suspended load transport by up to a factor four during the early uprush. The bed level near the inner surf zone is relatively steady during a swash cycle, but changes of O(cm/s) are measured near the mid swash zone where wave-swash interactions lead to strongly non-uniform flows. The two alternating swash events produce a dynamic equilibrium, with bed level changes up to a few mm induced by single swash events, but with net morphodynamic change over multiple events that is two orders of magnitude lower. Most of the intra-swash and the single-event-averaged bed level changes in the swash zone are caused by a redistribution of sediment within the swash. The transport of sediment across the surf-swash boundary is minor at intra-swash time scale, but becomes increasingly significant at swash-averaged time scales or longer (i.e., averaged over multiple swash events).
U2 - 10.1016/j.coastaleng.2019.103519
DO - 10.1016/j.coastaleng.2019.103519
M3 - Article
VL - 152
JO - Coastal engineering
JF - Coastal engineering
SN - 0378-3839
M1 - 103519
ER -