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Experimental study of wave-driven sediment suspension in flexible vegetation canopies with rippled beds
Applied Ocean Research, Volume: 173, Start page: 105146
Swansea University Authors:
Kristian Ions, Xin Wang, Dominic Reeve, Harshinie Karunarathna
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© 2026 The Authors. This is an open access article distributed under the terms of the Creative Commons CC-BY license.
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DOI (Published version): 10.1016/j.apor.2026.105146
Abstract
Laboratory experiments have been used to investigate the impact of flexible vegetation on sediment suspension over rippled sandy beds. Flexible vegetation mimics were examined across a range of wave conditions and stem densities, with rigid vegetation cases included for comparison. Measurements of v...
| Published in: | Applied Ocean Research |
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| ISSN: | 0141-1187 1879-1549 |
| Published: |
Elsevier BV
2026
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa72143 |
| Abstract: |
Laboratory experiments have been used to investigate the impact of flexible vegetation on sediment suspension over rippled sandy beds. Flexible vegetation mimics were examined across a range of wave conditions and stem densities, with rigid vegetation cases included for comparison. Measurements of velocity and suspended sediment concentration were used to compare near-bed hydrodynamics, bedform response, and sediment resuspension within the vegetation canopies. The results show that stem flexibility does not modify the dominant mechanisms governing near-bed sediment suspension when ripples are present. Flexible vegetation did not significantly modify ripple crest height or wavelength relative to bare sediment beds (p > 0.05), whereas rigid vegetation disrupted ripple geometry in the majority of cases tested (p < 0.05). Flexible canopies produced modest, statistically non-significant reductions in near-bed velocity of 0–5% relative to bare-bed conditions, confined to the lower 25% of the stem height, compared to reductions of 14–23% under rigid canopies (p < 0.001), which was observed over the entire stem length. Near-bed TKE within flexible canopies was statistically indistinguishable from bare-bed values across all conditions tested (p > 0.74), consistent with suppression of stem-generated vortex shedding due to stem reconfiguration and the preservation of ripple-induced turbulence as the dominant near-bed TKE source. Near-bed suspended sediment concentration collapsed onto a single power-law relationship with near-bed velocity across all vegetation types, densities, and wave conditions (R² = 0.97), with good agreement obtained using bare-bed ripple formulations applied with measured near-bed velocities. The results indicate that, for wave propagation over vegetated rippled beds, sediment resuspension is governed primarily by bedform-scale processes rather than by vegetation-induced TKE. The findings contrast with flat-bed and dense-canopy studies and highlight the importance of explicitly accounting for bedforms when modelling sediment transport in vegetated coastal environments. |
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| Keywords: |
Sediment suspension; Waves; Flexible vegetation; Nature based solution; Experimental study; Bedforms |
| College: |
Faculty of Science and Engineering |
| Funders: |
This research is supported by the Engineering and Physical Sciences Research Council (EPSRC) UK Doctoral Training Partnership of Swansea University (EP/T517987/1) grant. We would like to thank Dr. J.M. Horrillo-Caraballo for the assistance during the experiments. KI XW and HK acknowledge Leverhulme Trust Research Grant RPG-2023-235. We also extend thanks to The Great British Sasakawa Foundation Grant No. 6365 and the Disaster Prevention Research Institute (DPRI) of Kyoto University International Collaborative Research Grant 2023IG-02 for facilitating research collaboration between Swansea University and DPRI. NM is also supported by JICA/JST SATREPS Program (JPMJSA2110). Lastly, the authors acknowledge PDRI International Collaborative Research Grant FY2023. |
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105146 |