Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Numerical Investigation of Submerged Flexible Vegetation Dynamic and Wave Attenuation
Characteristics
Kai Yin, Sudong Xu, Mengqi Li, Shangpeng Gong, Yiran Wang
Department of Port, Waterway and Coastal Engineering, School of Transportation, Southeast University
Nanjing, Jiangsu Province, China

attenuation characteristics has important scientific significance andapplication value.

ABSTRACT
Dynamic characteristics and wave attenuation mechanism of flexible
vegetation is fundamental to ocean engineering and nature-based
coastal defense solutions. Based on simulation results by the flexible
vegetation dynamic model, relative water depth, wave height, wave
period and vegetation elastic modulus have noteworthy influences onsubmerged flexible vegetation dynamics. Meanwhile, simulation resultsby the coupled XBeach + FVDM model indicate that increasing
vegetation distribution density and length can result in larger wave
attenuation under the present investigation conditions. The findings ofthis research provide insights for flexible vegetation dynamic
characteristics and resulting wave attenuation mechanism.

Quantitative analysis on the responses of flexible vegetation dynamics
and resulting wave attenuation to influencing factors are the basis offurther understanding wave attenuation mechanism and carrying out thedesign as well as the construction of ecological vegetation embankment.
Based on a series of laboratory experiments, Augustin et al. (2009)indicated that emergent rigid vegetation can bring about a higher
amount of wave attenuation compared to near-emergent conditions.
Similarly, Rupprecht et al. (2017), Luhar et al. (2017), and Wang et al.
(2019) all concluded that water depth can play an important role indetermining the interaction between vegetation and waves. Aside fromthe water depth or the relative water depth, several lines of evidence
suggest that wave height and wave period also have a vital role in wave
attenuation by vegetation (Luhar et al., 2017; Rupprecht et al., 2017;
Yin et al., 2018). As demonstrated in Luhar et al. (2017), increasing
wave height can lead to decreasing wave attenuation by flexible
vegetation. Conversely, Yang et al. (2018) pointed out that a larger
incident wave height results in a larger wave height attenuation rate.
Similar controversy can also be found in investigations about theeffects of wave period. Luhar et al. (2017) indicated that wave
attenuation decreases with decreasing wave period. While Yin et al.
(2018) concluded that wave period has an opposite effect on wave
attenuation by vegetation for wave periods larger and less than 2 s.
Meanwhile, Maza et al. (2015) claimed that shorter wave periods canbring about higher wave attenuation by vegetation.

KEY WORDS: Flexible vegetation; wave attenuation; numericalsimulation.

INTRODUCTION
Wave attenuation by vegetation has emerged as a new opportunity forthe development of nature-based coastal defence (Marijnissen et al.,2020; Temmerman et al., 2013; Zhang et al., 2022). Investigating andconstructing such nature-based coastal defence have a pivotal role inenhancing the ability of coastal disaster prevention as well as
mitigation, and promoting ecological carrying capacity. Recently,
researchers have shown an increased interest in wave attenuation byflexible vegetation (Rupprecht et al., 2017; van Veelen et al., 2020; Yinet al., 2021a). Owing to the swaying effect of flexible vegetation, theability and mechanism of wave attenuation by flexible vegetation are
substantially different from that of rigid vegetation. On the basis ofsatisfactory developments in investigating wave attenuation by rigidvegetation (Kuang et al., 2021; Wang et al., 2019), the interaction
between waves and flexible vegetation has been a major area of interest
within the field of wave attenuation by vegetation (Hu et al., 2021; vanVeelen et al., 2021; Wang et al., 2020). In this context, theinvestigation of submerged flexible vegetation dynamic and wave

Aside from the above-mentioned incident wave conditions, vegetation
characteristics including the elastic modulus, distribution density, andlength can also affect the wave attenuation by vegetation. It hasconclusively been shown that vegetation flexibility has significant
influences on wave attenuation (Rupprecht et al., 2017; Tan et al., 2019;van Veelen et al., 2020), smaller vegetation flexibility leads to greater
blade motion and smaller relative velocity between wave andvegetation, thus bringing about less wave attenuation. Meanwhile, datafrom several sources have identified the increased wave attenuation

2783