Non-linear wave attenuation quantification model improves the estimation of wave attenuation efficiency of mangroves

Zhang, Yue; Yang, Yang; Yang, Ke; Tan, Xingyu; Sun, Xiang; Leng, Bing; Zhou, Changchang; Zhu, Bo-Kuan

doi:10.1016/j.ecss.2020.106927

Cited by 14 publications

(5 citation statements)

References 32 publications

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“…The canopy only contributes to wave attenuation for very large inundation depths that were not considered in this effort and, thus, was neglected. However, other studies have suggested the wave attenuation of canopies is significant at high water levels (Mazda et al 2006;He et al 2019;Zhang et al 2020). A simple cylinder represented the mangrove trunk.…”

Section: Mangrove Forest Modelmentioning

confidence: 99%

Wave attenuation of coastal mangroves at a near-prototype scale

Bryant¹,

Bryant²,

Provost³

et al. 2022

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A physical model study investigating the dissipation of wave energy by a 1:2.1 scale North American red mangrove forest was performed in a large-scale flume. The objectives were to measure the amount of wave attenuation afforded by mangroves, identify key hydrodynamic parameters influencing wave attenuation, and provide methodologies for application. Seventy-two hydrodynamic conditions, comprising irregular and regular waves, were tested. The analysis related the dissipation to three formulations that can provide estimates of wave attenuation for flood risk management projects considering mangroves: damping coefficient β, drag coefficient C𝐷, and Manning’s roughness coefficient 𝑛. The attenuation of the incident wave height through the 15.12 m long, 1:2.1 scale mangrove forest was exponential in form and varied from 13%–77%. Water depth and incident wave height strongly influenced the amount of wave attenuation. Accounting for differences in water depth using the sub-merged volume fraction resulted in a common fit of the damping coefficient as a function of relative wave height and wave steepness. The drag coefficient demonstrated a stronger relationship with the Keulegan–Carpenter number than the Reynolds number. The linear relationship between relative depth and Manning’s 𝑛 was stronger than that between Manning’s 𝑛 and either relative wave height or wave steepness.

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Section: Mangrove Forest Modelmentioning

confidence: 99%

Wave attenuation of coastal mangroves at a near-prototype scale

Bryant¹,

Bryant²,

Provost³

et al. 2022

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“…However, they estimated that steady current may lead to higher or lower wave attenuation, depending on the velocity ratio. In high and low tides events, mangroves shown higher attenuation ranging from 96% to 97% in high tides, and only 85% to 90% was observed during low tides [62]. The mangrove canopy and root system play a prominent role in reducing the wave height during high and low tides, respectively.…”

Section: Numerical Modelingmentioning

confidence: 98%

Mangroves As Coastal Bio-Shield: A Review of Mangroves Performance in Wave Attenuation

Kamil

Takaijudin

Hashim³

2021

Civ Eng J

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Mangroves have been recognized as soft structures that provide coastline protection. The capability of dampening waves helps minimize destruction from catastrophic events including erosive wave attacks, torrential storms, and tsunamis. Mangroves act as the first line of coastal defense in natural tragedies such as during the Super Typhoon Haiyan 2013 and Indian Ocean Tsunami 2004, whereby the leeward mangrove area encountered less damage than the unprotected area. This has further brought the attention of researchers to study the attenuation performance of these coastal vegetations. Based on an extensive literature review, this paper discusses the attenuation mechanism of mangroves, the factors influencing the dissipation performance, studies on mangrove dissipation via different approaches, the dissipation efficiency, mangrove conservation and rehabilitation efforts in Malaysia and implementation of mangrove as coastal bio-shield in other countries. The study highlights that mangrove parameters (such as species, width, density etc.) and wave parameters (such as wave period and incident wave height) are among the contributing factors in mangroves-induced wave attenuation, with different efficiency rates performed by different mangroves and waves parameters. Towards that end, several improvements are proposed for future research such as to incorporate all influencing dissipation factors with specific analysis for each species of mangroves, to perform validation on the studied mangroves attenuation capacity in different settings and circumstances, as well as to address the extent of protection by the rehabilitated mangroves. A systematic and effective management strategy incorporating ecological, forestry, and coastal engineering knowledge should be considered to ensure a sustainable mangroves ecosystem and promising coastline protection by mangroves. Doi: 10.28991/cej-2021-03091772 Full Text: PDF

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“…Plot (b) presents the trunk growth, represented by the diameter at breast height d BH (cm), and plot (c) displays changes in tree height h v (m), from Gijón Mancheño et al 49 Although the data in Figure 1 provides an indication of how the trunk diameter and tree height change as S. apetala trees grow, while Table 1 gives an impression of the relationship between root characteristics and tree height, the evolution of the total frontal area of S. apetala mangroves with age has not been measured in the field. For other mangrove species, the equivalent canopy width has been defined using several approaches, like assuming that the width of the canopy is given by the outer contour of the tree crown including 50 or neglecting 29,30 voids and empty areas. Other studies express the canopy area as a field of cylinders 51 , but without basing the canopy area on field measurements of the total branch area.…”

Section: Theoretical Background Mangrove Geometrymentioning

confidence: 99%

Integrating mangroves in dike designs: effect of tree growth and failure

Mancheño,

Vuik,

Wesenbeeck

et al. 2023

Preprint

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Mangrove forests reduce wave attack along tropical coastlines, decreasing the design requirements of coastal embankments. Wave reduction by mangroves depends on their surface area and stability against storms, but both aspects are often oversimplified or neglected in coastal protection designs. Here we present a framework to evaluate how mangrove belts influence embankment designs, including mangrove growth and failure by overturning and trunk breakage. This methodology is applied to Sonneratia apetala mangroves seawards from embankments in Bangladesh, considering forest widths between 10-1000 m (cross-shore). For design water levels of 5 m, wave reduction by mangrove forests shorter than 1 km mostly affects the slope protection and the bank erodibility, whereas the embankment height is less influenced by mangroves. Sonneratia apetala trees induce a relative maximum in wave attenuation by 10 years old, due to their large submerged canopy area. Once trees grow older than 20 years old, their canopy is emergent, and most wave attenuation is caused by trunk and roots. Canopy emergence exposes mangroves to wind loads, which are much larger than wave loads, and can cause tree failure during cyclones. These results stress the importance of including tree surface area and stability models when predicting coastal protection by mangroves.

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Non-linear wave attenuation quantification model improves the estimation of wave attenuation efficiency of mangroves

Cited by 14 publications

References 32 publications

Wave attenuation of coastal mangroves at a near-prototype scale

Wave attenuation of coastal mangroves at a near-prototype scale

Mangroves As Coastal Bio-Shield: A Review of Mangroves Performance in Wave Attenuation

Integrating mangroves in dike designs: effect of tree growth and failure

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