Wave attenuation in presence of mangroves: A sensitivity study for varying bottom slopes

Parvathy, K G; Bhaskaran, Prasad K.

doi:10.1177/1759313117702919

Cited by 40 publications

(6 citation statements)

References 19 publications

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“…Reference [36] studied the effectiveness of the Kanika Sands Mangrove Island near Dhamra in Odisha, India in attenuating cyclone-induced waves using the SWAN 40.81 model. Reference [37] conducted a sensitivity study with varying bottom slopes on wave attenuation in the presence of mangroves, and their results revealed that the wave height decays exponentially for mild slopes, found to be consistent with earlier studies; however, as the bottom steepness increases, the wave height reduction gradually increases. There are patches of mangrove forests along the coast of India, with varying vegetation density and diameter, but most of these areas are inaccessible for deploying sensors and conducting wave measurements.…”

Section: Introductionsupporting

confidence: 78%

Attenuation of Wave Energy Due to Mangrove Vegetation off Mumbai, India

et al. 2019

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Coastal regions of India are prone to sea level rise, cyclones, storm surges, and human-induced activities, resulting in flood, erosion, and inundation, and some of these impacts could be attributed to climate change. Mangroves play a very protective role against some of these coastal hazards. The primary aim of the study was to estimate wave energy attenuation by mangrove vegetation using modeling, and to validate the model results with measurements conducted off Mumbai coast, where a mangrove forest is present. Wave measurements were carried out from 5–8 August 2015 at three locations in a transect normal to the coast using surface-mounted pressure-level sensors in spring tide conditions. The measured data presented wave height attenuation of the order of 52%. Model set-up and sensitivity analyses were conducted to understand the model performance with respect to vegetation parameters. It was observed that wave attenuation increases with an increase in drag coefficient, vegetation density, and stem diameter. For a typical set-up in the Mumbai coastal region having a vegetation density of 0.175 per m2, stem diameter of 0.3 m, and drag coefficient varying from 0.4 to 1.5, the model reproduced attenuation ranging from 49% to 55%, which matches reasonably well with the measured data. Spectral analysis performed for the cases with and without vegetation very clearly portrays energy dissipation in the vegetation area. This study also highlights the importance of climate change and mangrove vegetation.

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Section: Introductionsupporting

confidence: 78%

Attenuation of Wave Energy Due to Mangrove Vegetation off Mumbai, India

et al. 2019

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“…According to Chen et al [54], the surge induced by wave was up to 0.55 m due to the giant typhoon generated waves and the steep sea-bottom slope in the northeastern coast of Taiwan. As reported by Parvathy and Bhaskaran [55], waves propagating on a steeper slope will have a severer energy dissipation over a narrower surf zone as compared to those on a gentler slope. Because of the gentle slope of NECS, the wave breaks early in the offshore and deforms gradually towards the shore [56].…”

Section: Contributions Of Wave-current Interaction To Water Level and Currentmentioning

confidence: 62%

Assessing the Impact of Wave–Current Interactions on Storm Surges and Waves during Cold Air Outbreaks in the Northern East China Sea

Hou

2021

JMSE

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Storm surges and disastrous waves induced by cold air outbreaks, a type of severe weather system, often impact the coastal economic development. Using the Climate Forecast System Reanalysis wind product and the Coupled Ocean–Atmosphere–Wave–Sediment Transport model, we developed a coupled numerical model and applied it to examine the interaction between surface gravity waves and ocean currents during cold air outbreaks in two case studies in the northern East China Sea. The results revealed that wave–current interactions improved the simulation accuracy, especially the water level, as verified by tidal station measurements. We conducted sensitivity experiments to explore the spatiotemporal variation of the impact of wave–current interactions on storm surges and waves in the northern East China Sea, away from the coastline. The wave-induced surge (up to 0.4 m) and the wave-induced current (up to 0.5 m/s) were found to be related to the difference between wave direction and current direction. The significant wave height difference (up to 0.5 m) was sensitive to the storm surge nearshore and sensitive to the current field offshore, while the mean wave direction change (up to 40°) was more sensitive to the current field than to the storm surge. Additionally, the wave–current interaction regulated the momentum balance and wave action balance, respectively. By comparison, the momentum residuals of pressure gradient, Coriolis force, Coriolis–Stokes force, and bottom stress, which were pronounced in different areas, were modulated more significantly by the wave effect than other terms. The dominant mechanisms of wave–current interactions on waves included the current-induced modification of energy generation caused by wind input, the current-induced modification of energy dissipation caused by whitecapping, and the current-induced wave advection.

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“…Wave energy dissipation caused by wave deformation is merely a function of wave parameters (height, length, and period) and depths, especially in intertidal zone morphology and can be estimated numerically if these parameters are known [1,22]. According to Parvathy and Bhaskaran (2017), steep slopes' shoal distances become short, while the reduction in the height and part of surface waves may be reflected from the steep bottom [23]. On the other hand, mild slopes have a longer wave traveling distance and the waves will decay on mild slopes via the mangroves.…”

Section: Wave Dissipation By Mangrovesmentioning

confidence: 99%

“…Higher wave energy attenuated in coastal regions changes directly towards the bathymetric profile [23]. The bathymetric condition also influences the size of waves with an increase in depth along the distance from the coastal regions.…”

Section: Bathymetrymentioning

confidence: 99%

“…Meanwhile, in the presence of mangroves forests, the resistance coefficient increased with the increasing water depth, resulting in a higher wave height reduction due to the larger submerged part of mangrove branches and leaves that clogs the water flow. According to Parvathy and Bhaskaran (2017), if the water depth is higher in the steep slope region, the waves attenuate the fastest as they travel through the roots, resulting in more drag resistance [23].…”

Section: Water Depthmentioning

confidence: 99%

See 1 more Smart Citation

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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Wave attenuation in presence of mangroves: A sensitivity study for varying bottom slopes

Cited by 40 publications

References 19 publications

Attenuation of Wave Energy Due to Mangrove Vegetation off Mumbai, India

Attenuation of Wave Energy Due to Mangrove Vegetation off Mumbai, India

Assessing the Impact of Wave–Current Interactions on Storm Surges and Waves during Cold Air Outbreaks in the Northern East China Sea

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

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