Interaction Between Water Waves and Vegetation

Asano, Toshiyuki; Deguchi, Hiroshi; Kobayashi, Nobuhisa

doi:10.1061/9780872629332.206

Cited by 29 publications

(32 citation statements)

References 3 publications

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“…The exponential decay solution captured adequately the wave trends observed by Asano et al (1988). Asano et al (1992) refined the analytical solution developed by Kobayashi et al (1993) to include small amplitude vegetation motion. A more correct estimation of F x is calculated using the relative velocity (u r ) between the horizontal particle velocity and swaying velocity of the stem (u v ),…”

Section: (A) (B)mentioning

confidence: 99%

Wave Dissipation by Vegetation

Anderson¹,

Smith²,

McKay³

2011

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PURPOSE:This Coastal and Hydraulics Engineering Technical Note (CHETN) provides a literature review of wave dissipation by vegetation. INTRODUCTION:Flooding resulting from hurricanes and other extreme storm events is a prominent risk along the coasts. These coastal areas are typically of low elevation and relief, making land and infrastructure highly susceptible to inundation by storm surge and waves. The severity of this threat is exacerbated by sea level rise and a possible increase in storm frequency and strength due to climate change. Although hard protection structures such as levees and floodwalls reduce flood risk, these structures may fail when storm conditions exceed the design threshold. There is a general consensus that wetlands, which often serve as transition zones between open water and dry land, could act as buffers and reduce storm surge and propagating waves substantially before they encounter coastal development. Unfortunately, the capability of wetlands to serve as protection during extreme storms is not understood fully or well documented; furthermore, water level and wave height reductions by vegetation are studied only in low-energy environments. Nonetheless, these studies present methods to quantify vegetationinduced wave attenuation for both modeling and design. This technical note focuses on the damping of propagating water waves by vegetation, but also discusses surge reduction briefly. Although waves may be encountered in freshwater environments (e.g., boat wakes, lake fetch, flood waves, etc.), this review focuses on coastal vegetation and resultant effects on flood and storm damage reduction.

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Section: (A) (B)mentioning

confidence: 99%

Wave Dissipation by Vegetation

Anderson¹,

Smith²,

McKay³

2011

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“…Kobayashi et al (1993) further developed the model of Dalrymple et al (1984) and showed that it predicted wave decay in submerged kelp vegetation in laboratory experiments with reasonable accuracy. They improved the model by including the swaying motion of the vegetation (Asano et al 1992) and later combined the wave model with a current model (Ota et al 2005). Mendez and Losada (2004) also used the model of Dalrymple et al (1984) and added the effect of…”

Section: Previous Studiesmentioning

confidence: 99%

“…Waves at ocean shores are known to lose energy in kelp beds (Mendez and Losada 2004), seagrass meadows (Fonseca and Cahalan 1992), saltmarsh vegetation (Knutson et al 1982;Möller and Spencer 2002;Möller 2006), and mangrove forests (Massel et al 1999;Mazda et al 2006;Quartel et al 2007). These vegetated belts act as buffer zones protecting nearshore structures and ecosystems (e.g., Asano et al 1992). In shallow lakes and wetlands, submerged and emergent vegetation are known to reduce resuspension of bottom sediments by decreasing the wave energy (Hamilton and Mitchell 1996;Horppila and Nurminen 2001;Houwing et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Wave Damping in Reed: Field Measurements and Mathematical Modeling

Lövstedt

Larson

2010

J. Hydraul. Eng.

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Wave damping in vegetation in shallow lakes reduces resuspension and thereby improves the light climate and decreases nutrient recycling. In this study, wave transformation in reed (Phragmites australis) was measured in a shallow lake. Theoretical models of wave height decay, based on linear wave theory, and transformation of the probability density function, using a wave-by-wave approach, were developed and compared to the collected data. Field data showed an average decrease in wave height of 4-5% m -1 within the first 5-14 m of the vegetation. Incident root-mean-square wave height varied between 1 and 8 cm, which is typical for the studied lake. A species-specific drag coefficient, C D , was found to be about 9 (most probable range: 3-25), and the model was relatively insensitive to moderate variations in this parameter. The coefficient showed little correlation with aReynolds number or a Keulegan-Carpenter number. The probability density function for the wave height did not change significantly, but for longer distances into the vegetation and higher incident waves it tended to be less similar to a Rayleigh distribution and more similar to the theoretically developed transformed distribution, where the higher waves are more damped than the smaller. Relationships developed in this study can be employed for management purposes to reduce resuspension and erosion in shallow lakes.

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“…Because of (3.16), the micro-scale variation of the leading order velocity field, (u (0) i , w (0) ), and the pressure fluctuation, p (1) , are forced by the macro-scale gradient of ζ (0) and p (0) . Recall that by assumption ν e is independent of time t and the fast coordinates x i .…”

Section: Formulation For Infinitesimal Wavesmentioning

confidence: 99%

“…Because of its influence on coastal inundation, beach erosion and the ecological health of coastal waters, the interaction of vegetation and storm waves or tsunamis have also received increasing attention. For example, wave flume simulation of kelps, seagrasses, and coastal trees have been conducted by [1,3,6,7,23,29,33,34,38,40,42], among others. Mathematical models starting from macro-scale (wavelength-scale) equations have been proposed by many (e.g., [5,16,22,17] etc.).…”

mentioning

confidence: 99%

Waves of intermediate length through an array of vertical cylinders

2013

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We report a semi-analytical theory of wave propagation through a vegetated water. Our aim is to construct a mathematical model for waves propagating through a lattice-like array of vertical cylinders, where the macro-scale variation of waves is derived from the dynamics in the micro-scale cells. Assuming infinitesimal waves, periodic lattice configuration, and strong contrast between the lattice spacing and the typical wavelength, the perturbation theory of homogenization (multiple scales) is used to derive the effective equations governing the macro-scale wave dynamics. The constitutive coefficients are computed from the solution of micro-scale boundary-value problem for a finite number of unit cells. Eddy viscosity in a unit cell is determined by balancing the time-averaged rate of dissipation and the rate of work done by wave force on the forest at a finite number of macro stations. While the spirit is similar to RANS scheme, less computational effort is needed. Using one fitting parameter, the theory is used to simulate three existing experiments with encouraging results. Limitations of the present theory are also pointed out.

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Interaction Between Water Waves and Vegetation

Cited by 29 publications

References 3 publications

Wave Dissipation by Vegetation

Wave Dissipation by Vegetation

Wave Damping in Reed: Field Measurements and Mathematical Modeling

Waves of intermediate length through an array of vertical cylinders

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