Laboratory study on wave dissipation by vegetation in combined current–wave flow

Hu, Zhan; Suzuki, Tomohiro; Zitman, T.J.; Uittewaal, Wim; Stive, M.J.F.

doi:10.1016/j.coastaleng.2014.02.009

Cited by 198 publications

(219 citation statements)

References 26 publications

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“…Although several formulations can be found in the literature to estimate the drag coefficient for waves damped by vegetation (e.g. : Mendez et al, 1999;Maza et al, 2013) and more recently, waves and current attenuation (Hu et al, 2014), none of them are especially fitted for solitary waves. Tanino and Nepf (2008) proposed an empirical formulation for the mean drag coefficient for random cylinders arrays:…”

Section: Discussion On the Numerical Approachmentioning

confidence: 99%

Tsunami wave interaction with mangrove forests: A 3-D numerical approach

Maza

Lara

Losada

2015

Coastal Engineering

157

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A three dimensional numerical approach based on IHFOAM to study the interaction of tsunami waves with mangrove forest is presented. As a first approximation, the problem is modelled by means of solitary waves impinging on emergent rigid cylinders. Two different conceptual approaches are implemented into IHFOAM. Solving the URANS equations provides a direct simulation of the flow field considering the actual geometry of the array of cylinders. A modified version of the volume-average URANS equations by introducing a drag force to model the momentum damping created by the cylinders is used in the second approach. Both the direct and macroscopic simulations are validated against laboratory experiments for wave damping with very high agreement. A large set of numerical experiments to analyse flow parameters and uniform and random cylinder array distributions are analysed and use to compare pros and cons of the different approaches. Large differences are found in the forces exerted on the vegetation for uniform and random distributions. Generalizations obtained from uniform arrangements could lead to underestimation of wave-exerted forces, especially for low dense configurations. Wave forces calculated with the macroscopic approach by means of the drag coefficient yields clear underestimations.

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Section: Discussion On the Numerical Approachmentioning

confidence: 99%

Tsunami wave interaction with mangrove forests: A 3-D numerical approach

Maza

Lara

Losada

2015

Coastal Engineering

157

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“…An exception is the study of Hu et al (2014), where drag forces were directly measured. Because the bulk drag coefficient is usually a result of computations, it also reflects all processes that are not or incorrectly captured in the model involved.…”

Section: Publicationmentioning

confidence: 99%

“…Möller et al, 1999Möller et al, , 2014 and ambient currents (Hu et al, 2014). Therefore, wave attenuation rates measured in moderate conditions cannot be applied directly to severe storm conditions, and physical or semiempirical modelling approaches are required for estimating the wave damping capacity of vegetated foreshores under these more extreme circumstances.…”

Section: Introductionmentioning

confidence: 99%

Nature-based flood protection: The efficiency of vegetated foreshores for reducing wave loads on coastal dikes

Vuik

Jonkman

Borsje

et al. 2016

Coastal Engineering

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219

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This paper analyses the effect of vegetation on wave damping under severe storm conditions, based on a combination of field measurements and numerical modelling. The field measurements of wave attenuation by vegetation were performed on two salt marshes with two representative but contrasting coastal wetland vegetation types: cordgrass (Spartina anglica) and grassweed (Scirpus maritimus). The former is found in salty environments, whereas the latter is found in brackish environments. The measurements have added to the range with the highest water depths and wave heights presented in the literature so far. A numerical wave model (SWAN) has been calibrated and validated using the new field data. It appeared that the model was well capable of reproducing the observed decay in wave height over the salt marsh. The model has been applied to compute the reduction of the incident wave height on a dike for various realistic foreshore configurations and hydraulic loading conditions. Additionally, the efficiency of vegetated foreshores in reducing wave loads on the dike has been investigated, where wave loads were quantified using a computed wave run-up height and wave overtopping discharge. The outcomes show that vegetated foreshores reduce wave loads on coastal dikes significantly, also for the large inundation depths that occur during storms and with the vegetation being in winter state. The effect of the foreshore on the wave loads varies with wave height to water depth ratio on the foreshore. The presence of vegetation on the foreshore extends the range of water depths for which a foreshore can be applied for effective reduction of wave loads, and prevents intense wave breaking on the foreshore to occur. This research demonstrates that vegetated foreshores can be considered as a promising supplement to conventional engineering methods for dike reinforcement.

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“…While canopy effects on the hydrodynamics inside a canopy have been clearly confirmed, conditions at the canopy edge are more variable (Gruber & Kemp 2010). The edge of seagrass canopies is a dynamic region were both ambient hydrodynamics and sediment transport are modified (Fonseca et al 1982, Granata et al 2001, Tigny et al 2007, Gruber & Kemp 2010, Nepf 2012a with non-linear responses to variable morphodynamics (Zhu et al 2003, Fontan et al 2013, Hu et al 2014. Spatial fragmentation of meadows, whether natural or anthropogenic, dramatically increases the frequency of edges; however, the impact of fragmentation on hydrodynamic edge effects has been poorly documented.…”

Section: Introductionmentioning

confidence: 99%

Impact of anthropogenically created canopy gaps on wave attenuation in a Posidonia oceanica seagrass meadow

Colomer¹,

Soler²,

Serra³

et al. 2017

Mar. Ecol. Prog. Ser.

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Fixed weights moorings, once removed, can create longitudinal gaps in seagrass meadows of different sizes, running perpendicular to the coast. We quantified the interactions between these longitudinal gaps and the hydrodynamic environment of the nearshore environment to determine their potential impact on seagrass meadow ecology. Within the meadow at leaf length distances from the edge, wave attenuation by the lateral vegetation next to the gap was approximately the same as attenuation by fully vegetated areas, and the wave attenuating capacity of the lateral, near-gap vegetation was independent of gap width. Gaps with widths less than twice the leaf length exhibited 8% wave attenuation and 11% turbulent kinetic energy attenuation, confirming that vegetation shelters at least small gaps. Despite similar capacity for wave attenuation, the longitudinal gaps influenced the architectural characteristics of the adjacent (lateral) meadow; lateral shoot density, percent cover and leaf length adjacent to the largest gap were 12, 16, and 20% lower than the fully vegetated site, respectively. Significant differences in the temporal variation of the mean lateral, near-gap seagrass percent cover and the leaf length indicated a strong dependence of the state of the canopy on temporal hydrodynamic conditions, which in turn were impacted by the presence of the gap. Our results quantify the interactions between gaps and lateral meadow vegetation, highlight the structural impact of traditional moorings and support improved management and conservation of seagrass meadows.

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Laboratory study on wave dissipation by vegetation in combined current–wave flow

Cited by 198 publications

References 26 publications

Tsunami wave interaction with mangrove forests: A 3-D numerical approach

Tsunami wave interaction with mangrove forests: A 3-D numerical approach

Nature-based flood protection: The efficiency of vegetated foreshores for reducing wave loads on coastal dikes

Impact of anthropogenically created canopy gaps on wave attenuation in a Posidonia oceanica seagrass meadow

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