Dynamics of Wave Setup over a Steeply Sloping Fringing Reef

Buckley, Mark; Lowe, Ryan J.; Hansen, Jeff E.; Dongeren, Ap van

doi:10.1175/jpo-d-15-0067.1

Cited by 64 publications

(90 citation statements)

References 52 publications

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“…Buckley et al () detailed experimental measurements of wave transformation and setup dynamics across a scaled physical model of a coral reef‐fringed coastline conducted in a 55 m long wave flume (Eastern Scheldt Flume) at Deltares, in the Netherlands (Figure ). Here these data are further analyzed to investigate the total water level variability across the reef profile and runup at the shoreline.…”

Section: Methodsmentioning

confidence: 99%

“…Coral reefs are often viewed as natural buffers to coastal storms by causing dissipation of SS waves through depth‐limited breaking and bottom friction (Cheriton et al, ; Ferrario et al, ; Quataert et al, ; Storlazzi et al, ). However, there have been few observations to quantify runup on reef‐fringed coastlines, and although reef morphologies clearly reduce the height of SS waves reaching a shoreline, there is evidence to suggest low‐frequency wave motions (Becker et al, ; Beetham et al, ; Merrifield et al, ; Nakaza & Hino, ; Nwogu & Demirbilek, ; Péquignet et al, ; Roeber & Bricker, ) and wave setup (Becker et al, ; Buckley et al, ; Quataert et al, ) can be enhanced in steeper reef environments relative to milder slope open coastlines. The latter is due to the dependence of wave setup on the cross‐shore profile of radiation stress gradients (Longuet‐Higgins & Stewart, ).…”

Section: Introductionmentioning

confidence: 99%

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Mechanisms of Wave‐Driven Water Level Variability on Reef‐Fringed Coastlines

et al. 2018

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Wave‐driven water level variability (and runup at the shoreline) is a significant cause of coastal flooding induced by storms. Wave runup is challenging to predict, particularly along tropical coral reef‐fringed coastlines due to the steep bathymetric profiles and large bottom roughness generated by reef organisms, which can violate assumptions in conventional models applied to open sandy coastlines. To investigate the mechanisms of wave‐driven water level variability on a reef‐fringed coastline, we performed a set of laboratory flume experiments on an alongshore uniform bathymetric profile with and without bottom roughness. Wave setup and waves at frequencies lower than the incident sea‐swell forcing (infragravity waves) were found to be the dominant components of runup. These infragravity waves were positively correlated with offshore wave groups, signifying they were generated in the surf zone by the oscillation of the breakpoint. On the reef flat and at the shoreline, the low‐frequency waves formed a standing wave pattern with energy concentrated at the natural frequencies of the reef flat, indicating resonant amplification. Roughness elements used in the flume to mimic large reef bottom roughness reduced low‐frequency motions on the reef flat and reduced wave runup by 30% on average, compared to the runs over a smooth bed. These results provide insight into sea‐swell and infragravity wave transformation and wave setup dynamics on steep‐sloped coastlines, and the effect that future losses of reef bottom roughness may have on coastal flooding along reef‐fringed coasts.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanisms of Wave‐Driven Water Level Variability on Reef‐Fringed Coastlines

et al. 2018

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“…To account for the extra kinetic energy present in the roller, S84 separated the incident wave energy flux into a wave and a roller contribution as follows:

E_{f} = E_{f, w} + E_{f, r}

with

E_{f, w} = ρ g c \frac{1}{T} \int_{0}^{T} η^{2} d t

E_{f, r} = \frac{1}{2} ρ_{r} \frac{A}{T} c^{2}

where ρ is the water density, g is the gravity constant, T is the wave period, η is the time‐varying surface elevation, and ρ r and A the surface roller mean density and area (see also Deigaard & Fredsøe, ). In practice, the surface roller constitutes the rotational part of the broken wave and accounts for the extra kinetic energy found in breaking and broken waves, see Svendsen (), Battjes (), and also the description of the roller model in Buckley et al (). Indeed, the term

E_{f, r}

represents the kinetic energy of the surface roller and the term

E_{f, w}

represents twice the wave energy flux calculated from the potential energy of the wave.…”

Section: Modeling Energy Dissipation Rates In Broken Waves With a Rolmentioning

confidence: 99%

Energy Dissipation in the Inner Surf Zone: New Insights From LiDAR‐Based Roller Geometry Measurements

et al. 2018

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The spatial and temporal variation of energy dissipation rates in breaking waves controls the mean circulation of the surf zone. As this circulation plays an important role in the morphodynamics of beaches, it is vital to develop better understanding of the energy dissipation processes in breaking and broken waves. In this paper, we present the first direct field measurements of roller geometry extracted from a LiDAR data set of broken waves to obtain new insights into wave energy dissipation in the inner surf zone. We use a roller model to show that most existing roller area formulations in the literature lead to considerable overestimation of the wave energy dissipation, which is found to be close to, but smaller than, the energy dissipation in a hydraulic jump of the same height. The role of the roller density is also investigated, and we propose that it should be incorporated into modified roller area formulations until better knowledge of the roller area and its link with the mean roller density is acquired. Finally, using previously published results from deepwater wave breaking studies, we propose a scaling law for energy dissipation in the inner surf zone, which achieves satisfactory results at both the time‐averaged and wave‐by‐wave scales.

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“…implications in wave transformation (Buckley et al, 2015) and wave runup (Osorio et al, 2017). Therefore, the conservation of the dune during such conditions is fundamental for the natural protection of the coastal area.…”

Section: Discussion: Storm Impact During Hurricane Events 10mentioning

confidence: 99%

“…10 respectively). This is particularly important, since previous studies have demonstrated the importance of accurately predicting wave setup in the prediction of coastal hazards, including erosion and inundation due to storms (Sheppard et al, 15 2005;Vetter et al, 2010;Storlazzi et al, 2011;Baldock et al, 2014;Buckley et al, 2015).…”

Section: Numerical Model Validation 15mentioning

confidence: 99%

The role of the reef-dune system in coastal protection in Puerto Morelos (Mexico)

Franklin

Torres-Freyermuth

Medellín

et al. 2017

Preprint

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Abstract. Reefs and sand dunes are critical morphological features providing natural coastal protection. Reefs dissipate around 90% of the incident wave energy through wave breaking, whereas sand dunes provide the final natural barrier against coastal flooding. The storm impact on coastal areas with these features depends on the relative elevation of the extreme water levels with respect to the sand dune morphology. However, despite the importance of the barrier reefs and dunes in 15 coastal protection, poor management practices have degraded these ecosystems, increasing their vulnerability to coastal flooding. The present study aims to investigate the role of the reef-dune system in coastal protection under current climatic conditions at Puerto Morelos, located in the Mexican Caribbean Sea. Firstly, a nonlinear non-hydrostatic numerical model (SWASH) is validated with experimental data from a physical model of a fringing reef. The numerical model predicts both energy transformation and runup statistics as compared with experimental results for two different reef crest geometries 20 conducted in a physical model. Thus, the numerical model is further used to investigate the role of the reef-dune degradation in coastal vulnerability. Wave hindcast information, tidal level, and a measured beach profile of the reef-dune system in Puerto Morelos are employed to predict extreme runup and estimate the storm impact scale for different scenarios. The numerical results show that ecosystem degradation has important implications for coastal protection against storms with return periods of less than 10 years. This highlights the importance of conservation of the system as a mitigation measure to 25 decrease coastal vulnerability and infrastructure losses in coastal areas in the short to medium term.

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Dynamics of Wave Setup over a Steeply Sloping Fringing Reef

Cited by 64 publications

References 52 publications

Mechanisms of Wave‐Driven Water Level Variability on Reef‐Fringed Coastlines

Mechanisms of Wave‐Driven Water Level Variability on Reef‐Fringed Coastlines

Energy Dissipation in the Inner Surf Zone: New Insights From LiDAR‐Based Roller Geometry Measurements

The role of the reef-dune system in coastal protection in Puerto Morelos (Mexico)

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