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Showing papers on "Wave height published in 2016"


Journal ArticleDOI
TL;DR: In this article, the effect of vegetation on wave damping under severe storm conditions, based on a combination of field measurements and numerical modelling, is analyzed and validated using the new field data.

156 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used satellite observations to study the climatology and trends of oceanic winds and waves in the Arctic Ocean in the summer season (August-September).
Abstract: Twenty years (1996–2015) of satellite observations were used to study the climatology and trends of oceanic winds and waves in the Arctic Ocean in the summer season (August–September). The Atlantic-side seas, exposed to the open ocean, host more energetic waves than those on the Pacific side. Trend analysis shows a clear spatial (regional) and temporal (interannual) variability in wave height and wind speed. Waves in the Chukchi Sea, Beaufort Sea (near the northern Alaska), and Laptev Sea have been increasing at a rate of 0.1–0.3 m decade−1, found to be statistically significant at the 90% level. The trend of waves in the Greenland and Barents Seas, on the contrary, is weak and not statistically significant. In the Barents and Kara Seas, winds and waves initially increased between 1996 and 2006 and later decreased. Large-scale atmospheric circulations such as the Arctic Oscillation and Arctic dipole anomaly have a clear impact on the variation of winds and waves in the Atlantic sector. Comparison ...

79 citations


Journal ArticleDOI
TL;DR: In this paper, a decade-long effort to estimate nearshore (20m depth) wave conditions based on offshore buoy observations along the California coast is described, and the buoy-driven wave model shows significant skill at most validation sites, but prediction errors for individual swell or sea events can be large.

78 citations


Journal ArticleDOI
01 Dec 2016-Energy
TL;DR: In this article, a fully nonlinear 2D RANS-based computational fluid dynamics (CFD) model was used to carry out an energy balance analysis of an onshore OWC.

70 citations


Journal ArticleDOI
TL;DR: In this article, an assessment of wave energy resources in the South China Sea (Malaysian Exclusive Economic Zone) using satellite altimeter is presented, where fifteen 2°×-2° zones were considered around the east coast of Peninsular Malaysia and the coast of East Malaysia, and the 10-year data were validated with buoy measurements and presented as the probability distribution of wave height and wave period.

56 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of coral reef geometry on wave transformation in the metropolitan area of Recife (MAR) on the northeast coast of Brazil has been studied using bathymetric measurements.

51 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the effect of WEC arrays on nearshore wave propagation using a modified version of an industry standard wave model, Simulating WAves Nearshore (SWAN), which allows the incorporation of device-specific WEC characteristics to specify obstacle transmission.

51 citations


Journal ArticleDOI
TL;DR: In this article, a new theoretical analysis has been developed, which is more applicable to the buoy considering hydraulic system, and the results of the study could be a guidance for the PTO design of the heaving buoy sets.

50 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of sea swell (SS) waves, infragravity (IG) waves and wave setup on maximum runup (Rmax) was investigated across different tidal stages on Fatato Island, Funafuti Atoll, Tuvalu.
Abstract: The influence of sea swell (SS) waves, infragravity (IG) waves, and wave setup on maximum runup (Rmax) is investigated across different tidal stages on Fatato Island, Funafuti Atoll, Tuvalu. Field results illustrate that SS waves are tidally modulated at the shoreline, with comparatively greater wave attenuation and setup occurring at low tide versus high tide. A shoreward increase in IG wave height is observed across the 100 m wide reef flat at all tidal elevations, with no tidal modulation of IG wave height at the reef flat or island shoreline. A 1-D shock-capturing Green-Naghdi solver is used to replicate the field deployment and analyze Rmax. Model outputs for SS wave height, IG wave height and setup at the shoreline match field results with model skill >0.96. Model outputs for Rmax are used to identify the temporal window when geomorphic activity can occur on the beach face. During periods of moderate swell energy, waves can impact the beach face at spring low tide, due to a combination of wave setup and strong IG wave activity. Under mean wave conditions, the combined influence of setup, IG waves and SS waves results in interaction with island sediment at midtide. At high tide, SS and IG waves directly impact the beach face. Overall, wave activity is present on the beach face for 71% of the study period, a significantly longer duration than is calculated using mean water level and topographic data.

49 citations


Journal ArticleDOI
TL;DR: In this article, the authors used a statistical modeling approach to predict the long-term shoreline change by using dune height as a variable in a statistical model and showed that the predicted dune heights are lower and the uncertainty decreases.
Abstract: Predictions of coastal evolution driven by episodic and persistent processes associated with storms and relative sea-level rise (SLR) are required to test our understanding, evaluate our predictive capability, and to provide guidance for coastal management decisions. Previous work demonstrated that the spatial variability of long-term shoreline change can be predicted using observed SLR rates, tide range, wave height, coastal slope, and a characterization of the geomorphic setting. The shoreline is not sufficient to indicate which processes are important in causing shoreline change, such as overwash that depends on coastal dune elevations. Predicting dune height is intrinsically important to assess future storm vulnerability. Here, we enhance shoreline-change predictions by including dune height as a variable in a statistical modeling approach. Dune height can also be used as an input variable, but it does not improve the shoreline-change prediction skill. Dune-height input does help to reduce prediction uncertainty. That is, by including dune height, the prediction is more precise but not more accurate. Comparing hindcast evaluations, better predictive skill was found when predicting dune height (0.8) compared with shoreline change (0.6). The skill depends on the level of detail of the model and we identify an optimized model that has high skill and minimal overfitting. The predictive model can be implemented with a range of forecast scenarios, and we illustrate the impacts of a higher future sea-level. This scenario shows that the shoreline change becomes increasingly erosional and more uncertain. Predicted dune heights are lower and the dune height uncertainty decreases.

48 citations


Journal ArticleDOI
TL;DR: In this article, the authors show that the consecutive effect of even tiny fluctuations in the profile of the ocean floor (the bathymetry) can cause unexpectedly strong fluctuations in wave height of tsunamis, with maxima several times higher than the average wave height.
Abstract: Fluctuations in the profile of the ocean floor can lead to large variations in tsunami wave height. A theory linking this behaviour to the branched flow characteristics of electron waves through semiconductors may provide a framework for prediction. Tsunamis exhibit surprisingly strong height fluctuations. An in-depth understanding of the mechanisms that lead to these variations in wave height is a prerequisite for reliable tsunami forecasting. It is known, for example, that the presence of large underwater islands1 or the shape of the tsunami source2 can affect the wave heights. Here we show that the consecutive effect of even tiny fluctuations in the profile of the ocean floor (the bathymetry) can cause unexpectedly strong fluctuations in the wave height of tsunamis, with maxima several times higher than the average wave height. A novel approach combining stochastic caustic theory and shallow water wave dynamics allows us to determine the typical propagation distance at which the strongly focused waves appear. We demonstrate that owing to this mechanism the small errors present in bathymetry measurements can lead to drastic variations in predicted tsunami heights. Our results show that a precise knowledge of the ocean’s bathymetry is absolutely indispensable for reliable tsunami forecasts.

Journal ArticleDOI
TL;DR: In this article, complex analytical structure of Stokes wave for two-dimensional potential flow of the ideal incompressible fluid with free surface and infinite depth is analyzed and a conformal map is used to map a free fluid surface of the stokes wave into the real line with fluid domain mapped into the lower complex half-plane.
Abstract: Complex analytical structure of Stokes wave for two-dimensional potential flow of the ideal incompressible fluid with free surface and infinite depth is analyzed. Stokes wave is the fully nonlinear periodic gravity wave prop agating with the constant velocity. Simulations with the quadruple (32 digits) and variable precisions (more than 200 digits) are performed to find Stokes wave with high accuracy and study the Stokes wave approaching its limiting form with radians angle on the crest. A conformal map is used that maps a free fluid surface of Stokes wave into the real line with fluid domain mapped into the lower complex half-plane. The Stokes wave is fully characterized by the complex singularities in the upper complex half-plane. These singularities are addressed by rational (Pade) interpolation of Stokes wave in the complex plane. Convergence of Pade approximation to the density of complex poles with the increase in the numerical precision and subsequent increase in the number of approximating poles reveals that the only singularities of Stokes wave are branch points connected by branch cuts. The converging densities are the jumps across the branch cuts. There is one square-root branch point per horizontal spatial period λ of Stokes wave located at the distance from the real line. The increase in the scaled wave height from the linear limit to the critical value marks the transition from the limit of almost linear wave to a strongly nonlinear limiting Stokes wave (also called the Stokes wave of the greatest height). Here, H is the wave height from the crest to the trough in physical variables. The limiting Stokes wave emerges as the singularity reaches the fluid surface. Tables of Pade approximation for Stokes waves of different heights are provided. These tables allow to recover the Stokes wave with the relative accuracy of at least 10−26. The number of poles in tables increases from a few for near-linear Stokes wave up to about hundred poles to highly nonlinear Stokes wave with

Journal ArticleDOI
TL;DR: In this article, the authors presented a comprehensive numerical simulation of a point wave absorber in deep water and analyzed the effects of wave characteristics on energy conversion and device efficiency, including wave height and wave period, as well as the device diameter, draft and damping coefficient.
Abstract: In this paper, we present a comprehensive numerical simulation of a point wave absorber in deep water. Analyses are performed in both the frequency and time domains. The converter is a two-body floating-point absorber (FPA) with one degree of freedom in the heave direction. Its two parts are connected by a linear mass-spring-damper system. The commercial ANSYS-AQWA software used in this study performs well in considering validations. The velocity potential is obtained by assuming incompressible and irrotational flow. As such, we investigated the effects of wave characteristics on energy conversion and device efficiency, including wave height and wave period, as well as the device diameter, draft, geometry, and damping coefficient. To validate the model, we compared our numerical results with those from similar experiments. Our study results can clearly help to maximize the converter’s efficiency when considering specific conditions.

Journal ArticleDOI
TL;DR: In this paper, the sensitivity of a hydrodynamic model and a coupled wind-wave and circulation model system (ADCIRC + SWAN) to Manning's n coefficient, wind waves and circulation interaction (wave setup), minimum depth (H0) in the wetting and drying algorithm, and spatially constant horizontal eddy viscosity (ESLM) forced by tides and hurricane winds was investigated.
Abstract: Large estuaries are especially vulnerable to coastal flooding due to the potential of combined storm surges and riverine flows. Numerical models can support flood prevention and planning for coastal communities. However, while recent advancements in the development of numerical models for storm surge prediction have led to robust and accurate models; an increasing number of parameters and physical processes’ representations are available to modelers and engineers. This study investigates uncertainties associated with the selection of physical parameters or processes involved in storm surge modeling in large estuaries. Specifically, we explored the sensitivity of a hydrodynamic model (ADCIRC) and a coupled wind-wave and circulation model system (ADCIRC + SWAN) to Manning’s n coefficient, wind waves and circulation interaction (wave setup), minimum depth (H0) in the wetting and drying algorithm, and spatially constant horizontal eddy viscosity (ESLM) forced by tides and hurricane winds. Furthermore, sensitivity analysis to Manning’s n coefficient and the interaction of waves and circulation were analyzed by using three different numerical meshes. Manning’s coefficient analysis was divided into waterway (rivers, bay and shore, and open ocean) and overland. Overall, the rivers exhibited a larger sensitivity, and M2 amplitude and maximum water elevations were reduced by 0.20 m and 0.56 m, respectively, by using a high friction value; similarly, high friction reduced maximum water levels up to 0.30 m in overland areas; the wave setup depended on the offshore wave height, angle of breaking, the profile morphology, and the mesh resolution, accounting for up to 0.19 m setup inside the bay; minimum depth analysis showed that H0 = 0.01 added an artificial mass of water in marshes and channels, meanwhile H = 0.1 partially solved this problem; and the eddy viscosity study demonstrated that the ESLM = 40 values reduced up to 0.40 m the peak of the maximum water levels in the upper side of narrow rivers.

Journal ArticleDOI
TL;DR: In this article, wave power atlas is generated for the Aegean Sea for years from 1999 to 2013 using a third-generation spectral wave model MIKE 21 SW, which was then interpolated to 10-min interval data.

Journal ArticleDOI
TL;DR: In this paper, the authors used high-frequency in situ measurements of water depths and near-bed velocities to estimate bed shear stress on an open intertidal flat in the Yangtze Delta, China.
Abstract: Accurate estimations for the bed shear stress are essential to predict the erosion and deposition processes in estuaries and coasts. This study used high-frequency in situ measurements of water depths and near-bed velocities to estimate bed shear stress on an open intertidal flat in the Yangtze Delta, China. To determine the current-induced bed shear stress (τc) the in situ near-bed velocities were first decomposed from the turbulent velocity into separate wave orbital velocities using two approaches: a moving average (MA) and energy spectrum analysis (ESA). τc was then calculated and evaluated using the log-profile (LP), turbulent kinetic energy (TKE), modified TKE (TKEw), Reynolds stress (RS), and inertial dissipation (ID) methods. Wave-induced bed shear stress (τw) was estimated using classic linear wave theory. The total bed shear stress (τcw) was determined based on the Grant–Madsen wave–current interaction model (WCI). The results demonstrate that when the ratio of significant wave height to water depth (Hs/h) is greater than 0.25, τcw is significantly overestimated because the vertical velocity fluctuations are contaminated by the surface waves generated by high winds. In addition, wind enhances the total bed shear stress as a result of the increases in both τw and τc generated by the greater wave height and reinforcing of vertical turbulence, respectively. From a comparison of these various methods, the TKEw method associated with ESA decomposition was found to be the best approach because: (1) this method generates the highest mean index of agreement; (2) it uses vertical velocities that are less affected by Doppler noise; and (3) it is less sensitive to the near-bed stratification structure and uncertainty in bed location and roughness.

Journal ArticleDOI
TL;DR: In this article, the capabilities of M5′ Decision Tree algorithm are implemented for predicting the wave runup using existing laboratory data and the performance of developed models is evaluated with statistical measures.

Journal ArticleDOI
TL;DR: In this paper, the influence of infragravity waves on sand suspension and cross-shore transport was investigated using two field data sets of near-bed velocity, pressure, and sediment concentration.
Abstract: Two field data sets of near-bed velocity, pressure, and sediment concentration are analyzed to study the influence of infragravity waves on sand suspension and cross-shore transport. On the moderately sloping Sand Motor beach (≈1:35), the local ratio of infragravity wave height to sea-swell wave height is relatively small (HIG/HSW 0.4), most sand is suspended during negative infragravity velocities, and qIG is offshore directed. The infragravity contribution to the total sand flux is considerably larger and reaches up to ≈60% during energetic conditions. On the whole, HIG/HSW is a good indicator for the infragravity-related sand suspension mechanism and the resulting infragravity sand transport direction and relative importance.

Journal ArticleDOI
TL;DR: In this paper, an existing 1DV boundary layer model, based on the horizontal component of the incompressible Reynolds-averaged Navier-Stokes (RANS) equations, is newly extended to incorporate a transitional variant of the standard two-equation k-ω turbulence closure.

Journal ArticleDOI
TL;DR: In this article, the authors evaluate the accuracy of probabilistic forecasts of wave energy flux from a variety of methods, including unconditional and conditional kernel density estimation, univariate and bivariate autoregressive moving average generalised auto-gressive conditional heteroskedasticity (ARMA-GARCH) models, and a regression-based method.

Journal ArticleDOI
TL;DR: In this article, a series of two-dimensional experiments were performed at the University of Padua in 1968 considering a scale characteristic cross section of the Vajont basin near the dam: the landslide was pushed into the stored water by a moving plate over the sliding surface and the maximum wave run-up along the opposite mountain side was measured as a function of the landslide falling time.
Abstract: The Vajont disaster was caused in 1963 by a landslide of about 270 million cubic meters that fell into a hydroelectric reservoir and generated a wave about 200 m high which overtopped the dam and caused 1917 casualties. With the aim of assessing why the real wave height was underestimated, a series of two-dimensional experiments were performed at the University of Padua in 1968 considering a scale characteristic cross section of the Vajont basin near the dam: the landslide was pushed into the stored water by a moving plate over the sliding surface and the maximum wave run-up along the opposite mountain side was measured as a function of the landslide falling time. Some of these results have been compared to smoothed particle hydrodynamics numerical simulations in which both water and noncohesive sediment are simulated as weakly compressible fluid; water is treated as Newtonian fluid while a proper rheological model is adopted for the landslide to mimic its non-Newtonian behavior. The computed fall...

Journal ArticleDOI
TL;DR: In this article, a two-dimensional numerical model is developed to predict local scour around submarine pipelines induced by the orbital fluid motion under surface water waves, instead of being simplified to oscillatory flow, the wave motion is modeled using a fully nonlinear wave model.

Journal ArticleDOI
TL;DR: In this paper, a general framework for reducing dimensionality of wave-driver inputs to morphodynamic models is proposed to account for dependencies with global atmospheric circulation fields and deal simultaneously with seasonality, interannual variability, long-term trends, and autocorrelation of wave height, wave period, and wave direction.
Abstract: Interest in understanding long-term coastal morphodynamics has recently increased as climate change impacts become perceptible and accelerated. Multiscale, behavior-oriented and process-based models, or hybrids of the two, are typically applied with deterministic approaches which require considerable computational effort. In order to reduce the computational cost of modeling large spatial and temporal scales, input reduction and morphological acceleration techniques have been developed. Here we introduce a general framework for reducing dimensionality of wave-driver inputs to morphodynamic models. The proposed framework seeks to account for dependencies with global atmospheric circulation fields and deals simultaneously with seasonality, interannual variability, long-term trends, and autocorrelation of wave height, wave period, and wave direction. The model is also able to reproduce future wave climate time series accounting for possible changes in the global climate system. An application of long-term shoreline evolution is presented by comparing the performance of the real and the simulated wave climate using a one-line model.

Journal ArticleDOI
TL;DR: In this paper, an improved mesh update method is used to dynamically configure the computational meshes solving the Navier-Stokes equations for viscous and incompressible free surface flows with the volume of fluid (VOF) method.
Abstract: This paper presents a numerical analysis of the nonlinear interaction between water waves and the movable superstructure of a coastal bridge. An improved mesh update method is used to dynamically configure the computational meshes solving the Navier-Stokes equations for viscous and incompressible free surface flows with the volume of fluid (VOF) method. To maintain the mesh quality as the bridge deck is displaced, the computational domain is separated into several parts corresponding to a specific type of body motion. The numerical model results have been compared with the laboratory experiments conducted at Oregon State University with good agreement. This hydrodynamic model is then used to simulate the failure process of the prototype U.S. Highway 90 (US 90) Bridge during Hurricane Katrina (2005). It is found that the bridge deck is most vulnerable to be displaced by the waves when the bridge is partially submerged because of the combined effects of the vertical and horizontal wave forces. Numerical experiments of the US 90 Bridge shed light on the sway and heave responses of the bridge deck to different wave height conditions. It is shown that a significant wave height of 2.6 m would result in a failure of the bridge deck. A critical wave height (2 m) based on the incipient motion of the bridge deck is recommended for screening the vulnerability of other bridges similar to the US 90 Bridge in hurricane-prone areas. Moreover, the computed maximum heave response can be used as a reference for engineers to design the shear key height to prevent a bridge deck from horizontal displacement.

Journal ArticleDOI
TL;DR: Present work aims in reducing the error in numerical wave forecast made by INCOIS at four stations along Indian coastline using a hybrid approach that will add to the usefulness of the wave forecasts given by InCOIS to its stake holders.

Journal ArticleDOI
TL;DR: In this article, the cliff top response to wave impacts was characterized using microseismic shaking in a frequency band (20-45 Hz) sensitive to wave breaking and cliff impacts.
Abstract: Concurrent observations of waves at the base of a southern California coastal cliff and seismic cliff motion were used to explore wave–cliff interaction and test proxies for wave forcing on coastal cliffs. Time series of waves and sand levels at the cliff base were extracted from pressure sensor observations programmatically and used to compute various wave impact metrics (e.g. significant cliff base wave height). Wave–cliff interaction was controlled by tide, incident waves, and beach sand levels, and varied from low tides with no wave–cliff impacts, to high tides with continuous wave–cliff interaction. Observed cliff base wave heights differed from standard Normal and Rayleigh distributions. Cliff base wave spectra levels were elevated at sea swell and infragravity frequencies. Coastal cliff top response to wave impacts was characterized using microseismic shaking in a frequency band (20–45 Hz) sensitive to wave breaking and cliff impacts. Response in the 20–45 Hz band was well correlated with wave–cliff impact metrics including cliff base significant wave height and hourly maximum water depth at the cliff base (r2 = 0.75). With site-specific calibration relating wave impacts and shaking, and acceptable anthropogenic (traffic) noise levels, cliff top seismic observations are a viable proxy for cliff base wave conditions. The methods presented here are applicable to other coastal settings and can provide coastal managers with real time coastal conditions. Copyright © 2016 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this paper, the Hilbert-Huang transformation was used to detect very low frequency (VLF, 0.001-0.005 Hz) wave resonance on coral reef islands.
Abstract: Very-low frequency (VLF, 0.001-0.005 Hz) waves are important drivers of flooding of low-lying coral reef-islands. In particular, VLF wave resonance is known to drive large wave runup and subsequent overwash. Using a five-month dataset of water levels and waves collected along a cross-reef transect on Roi-Namur Island in the Republic of the Marshall Islands, the observed VLF motions were categorized into four different classes: (1) resonant, (2) (non-resonant) standing, (3) progressive-growing and (4) progressive-dissipative waves. Each VLF class is set by the reef flat water depth and, in the case of resonance, the incident-band offshore wave period. Using an improved method to identify VLF wave resonance, we find that VLF wave resonance caused prolonged (∼0.5 – 6.0 hr), large-amplitude water surface oscillations at the inner reef flat ranging in wave height from 0.14 to 0.83 m. It was induced by relatively long-period, grouped, incident-band waves, and occurred under both storm and non-storm conditions. Moreover, observed resonant VLF waves had non-linear, bore-like wave shapes, which likely have a larger impact on the shoreline than regular, sinusoidal waveforms. As an alternative technique to the commonly used Fast Fourier Transformation, we propose the Hilbert-Huang Transformation that is more computationally expensive but can capture the wave shape more accurately. This research demonstrates that understanding VLF waves on reef flats is important for evaluating coastal flooding hazards. This article is protected by copyright. All rights reserved.

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the coastal impact induced by a generic wave farm operating in the central part of the Portuguese continental coastal environment, south of Lisbon, in order to identify better the most relevant wave patterns in the target area.

Journal ArticleDOI
TL;DR: In this paper, a numerical study was carried out based on one-dimensional weakly dispersive, highly nonlinear Boussinesq equations to assess the impact of reef-flat excavation pits on wave transformation, a numerical model was shown to satisfactorily reproduce the observed sea and swell (SS) and infragravity (IG) frequency band wave heights for a moderate amplitude wave event.

Journal ArticleDOI
TL;DR: XBeach, a process-based numerical model designed to simulate morphologic change during extreme storm events, was calibrated and compared to observations from a large-scale laboratory dune erosion experiment.