A third-generation numerical wave model to compute random, short-crested waves in coastal regions with shallow water and ambient currents (Simulating Waves Nearshore (SWAN)) has been developed, implemented, and validated. The model is based on a Eulerian formulation of the discrete spectral balance of action density that accounts for refractive propagation over arbitrary bathymetry and current fields. It is driven by boundary conditions and local winds. As in other third-generation wave models, the processes of wind generation, whitecapping, quadruplet wave-wave interactions, and bottom dissipation are represented explicitly. In SWAN, triad wave-wave interactions and depth-induced wave breaking are added. In contrast to other third-generation wave models, the numerical propagation scheme is implicit, which implies that the computations are more economic in shallow water. The model results agree well with analytical solutions, laboratory observations, and (generalized) field observations.

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A third-generation wave model for coastal regions: 1. Model description and validation

to be done in this area. Face recognition is a problem that scarcely clamoured for attention before the computer age but, having surfaced, has involved a wide range of techniques and has attracted the attention of some fine minds (David Mumford was a Fields Medallist in 1974). This singular application of mathematical modelling to a messy applied problem of obvious utility and importance but with no unique solution is a pretty one to share with students: perhaps, returning to the source of our opening quotation, we may invert Duncan's earlier observation, 'There is an art to find the mind's construction in the face!'.

Linear and nonlinear waves, by G. B. Whitham. Pp.636. £50. 1999. ISBN 0 471 35942 4 (Wiley).

Changes in climate extremes and their impacts on the natural physical environment: An overview of the IPCC SREX report

Wind speeds over the world’s oceans have increased over the past two decades, as have wave heights. Studies of climate change typically consider measurements or predictions of temperature over extended periods of time. Climate, however, is much more than temperature. Over the oceans, changes in wind speed and the surface gravity waves generated by such winds play an important role. We used a 23-year database of calibrated and validated satellite altimeter measurements to investigate global changes in oceanic wind speed and wave height over this period. We find a general global trend of increasing values of wind speed and, to a lesser degree, wave height, over this period. The rate of increase is greater for extreme events as compared to the mean condition.

https://researchbank.swinburne.edu.au/file/bca43746-6f16-4ad2-a4b7-27f8d8d60fed/1/PDF (Published version).pdf

Global trends in wind speed and wave height over the past 25 years

In this paper, we focus on the implementation and verification of an extended Boussinesq model for surf zone hydrodynamics in two horizontal dimensions The time-domain numerical model is based on the fully nonlinear Boussinesq equations As described in Part I of this two-part paper, the energy dissipation due to wave breaking is modeled by introducing an eddy viscosity term into the momentum equations, with the viscosity strongly localized on the front face of the breaking waves Wave runup on the beach is simulated using a permeable-seabed technique We apply the model to simulate two laboratory experiments in large wave basins They are wave transformation and breaking over a submerged circular shoal and solitary wave runup on a conical island Satisfactory agreement is found between the numerical results and the laboratory measurements

Boussinesq modeling of wave transformation, breaking, and runup. ii: 2d

The influence of global climate change due to greenhouse effects on the earth’s environment will require impact assessment, mitigation and adaptation strategies for the future of our society. This study predicts future ocean wave climate in comparison with present wave climate based on the atmospheric general circulation model and global wave model. The annual averaged and extreme sea surface winds and waves are analyzed in detail. There are clear regional dependences of both annual average and also extreme wave height changes from present to future climates. The wave heights of future climate will increase at both middle latitudes and also in the Antarctic Ocean, with a decrease at the equator.

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Projection of Extreme Wave Climate Change under Global Warming

An extensive series of labroatory tests were conducted and these tests led to the development of a formula to predict runup elevation of random waves on gentle, smooth and impermeable slopes, as a function of surf similarity parameter. On gentle slopes, a bore advancing into the shoreline cannot run up when the back‐rush of a preceding bore is large or when it is overtaken and captured by a subsequent large bore. No correspondence between individual running‐up bores and runup crests can be seen; the number of runup crests is reduces compared to the number of running‐up bores. This paper also proposed a formula for the ratio of the number of runup crests to that of incident waves; the formula can be used to estimate the mean repetition period of runup crests. The formulas proposed here are applicable to slopes, tan θ, ranging from 1/30 to 1/5 and to deep water significant wave steepness ranging from 0.007 to 0.07.

Random wave runup height on gentle slope

Typhoon Haiyan, which struck the Philippines in November 2013, was an extremely intense tropical cyclone that had a catastrophic impact. The minimum central pressure of Typhoon Haiyan was 895 hPa, making it the strongest typhoon to make landfall on a major island in the western North Pacific Ocean. The characteristics of Typhoon Haiyan and its related storm surge are estimated by numerical experiments using numerical weather prediction models and a storm surge model. Based on the analysis of best hindcast results, the storm surge level was 5–6 m and local amplification of water surface elevation due to seiche was found to be significant inside Leyte Gulf. The numerical experiments show the coherent structure of the storm surge profile due to the specific bathymetry of Leyte Gulf and the Philippines Trench as a major contributor to the disaster in Tacloban. The numerical results also indicated the sensitivity of storm surge forecast.

Local amplification of storm surge by Super Typhoon Haiyan in Leyte Gulf.

: The Coastal Inlets Research Program (CIRP) of the U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, in collaboration with two universities in Japan, has developed a spectral wave transformation numerical model to address needs of the U.S. Army Corps of Engineers navigation projects. The model is called CMS-Wave and is part of Coastal Modeling System (CMS) developed in the CIRP. The CMS is a suite of coupled models operated in the Surface-water Modeling System (SMS), which is an interactive and comprehensive graphical user interface environment for preparing model input, running models, and viewing and analyzing results. CMS-Wave is designed for accurate and reliable representation of wave processes affecting operation and maintenance of coastal inlet structures in navigation projects as well as in risk and reliability assessment of shipping in inlets and harbors. Important wave processes at coastal inlets are diffraction, refraction, reflection, wave breaking, and dissipation mechanisms, and the wave-current interaction. The effect of locally-generated wind can also be significant during wave propagation at inlets. This report provides information on CMS-Wave theory, numerical implementation, and SMS interface. A set of examples are given to demonstrate the model's applicability for storm-damage assessment, modification to jetties including jetty extensions, jetty breaching, addition of spurs to inlet jetties, and planning and design of nearshore reefs and barrier islands to protect beaches and promote navigation reliability.

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CMS-Wave: A nearshore spectral wave processes model for coastal inlets and navigation projects

This paper examines the applicability of a neural network to analyze model test data of the stability of rubble-mound breakwaters. The neural network is an information-processing system, modeled on the structure of the human brain, that is able to deal with information whose interrelation is not clear. Seven parameters concerning the stability of rock slopes are used: the stability number, the damage level, the number of attacking waves, the surf-similarity parameter, the permeability parameter, the dimensionless water depth in front of the structure, and the spectral shape parameter. The damage levels predicted by the neural network, calibrated by using a part of Van der Meer’s 1988 experimental data, agree satisfactorily well with the measured damage levels of another part of the data source by Van der Meer 1988 and by Smith et al.’s 1992 data. The agreement between the predicted stability numbers by the neural network and the measured stability numbers is also good.

Hajime Mase

Papers

Projection of Extreme Wave Climate Change under Global Warming

Random wave runup height on gentle slope

Local amplification of storm surge by Super Typhoon Haiyan in Leyte Gulf.

CMS-Wave: A nearshore spectral wave processes model for coastal inlets and navigation projects

Neural network for stability analysis of rubble-mound breakwaters