bluuebunny/crossref_metadata_2025 huggingface dataset:
INFLUENCE OF EL NINOS ON CALIFORNIA'S WAVE CLIMATE
Authors: Seymour Richard J. , Strange R. Rea , Cayan Daniel R. , Nathan Robert A.
Published: June 2019

Waves with exceptional height and periods caused severe damage along the coast of California in 1982-83. Because these large wave events coincided with a strong El Nino-Southern Oscillation (ENSO) climatic anomaly, which occurs 20-25 times per century, there was interest in determining if the extreme waves resulted from the ENSO or its related features. The meteorological setting featured a very large and intense low pressure zone over the north-central Pacific. Associated with this Pacific-wide pattern, a series of large mid-latitude storms developed at about weekly intervals and produced exceptionally long fetchs directed at the California Coast. Two time series of extreme wave events, using buoy data after 1981 and hindcasts before, were used covering the period from 1900 to 1984. One series considered waves with significant heights greater than 3 m (10 ft) and the second for those greater than 6 m (20 ft.) These were compared with a time history of ENSOs for the same period. A strong association was established between northern hemisphere winters during ENSO years and large wave events in Southern California. Strong ENSO winters had the largest storm waves, moderate ENSOs less intense waves, and weak ENSOs tended not to have storm waves greater than the threshold value used in this study. The correlation between large waves and ENSO years is significant at the 1% level. The correlation between lack of large waves and non-ENSO years is significant at the 0.5% level. Because of the great southerly extent of the most energetic storms, a large number of energetic wave trains approach the coast from the west, rather than the northwest, as previously assumed by many. ENSO winters are responsible for producing all of the wave events in this study with both heights greater than 6 m and periods of peak energy longer than 19 seconds. Five out of nine eastern Pacific tropical storms making landfalls on California in the 85 year period occurred during the late northern summer of ENSO years.
ON A SEQUENTIAL BEHAVIOUR OF SEA-STATES
Authors: Sanchez-Arcilla A.
Published: June 2019

Probability distributions theoretically derived for gaussian, stationary processes are applied here to the sequential behaviour of sea-states. This behaviour defined by the curve of evolution of significant wave-height, Hs(t), is characterized by variables such as: intensity of storm peaks,time between beginnings of storms, average duration of calms and storms, average number of consecutive storms, expected value of the extremal storm peak, etc. The distributions obtained for these variables heve been tested with 5 years of wave data, recorded in the north coast of Spain. The agreement obtained is satisfactory in most cases, showing the validity of the approach and its applicability to situations in which only a limited amount of data is available. However, in cases where a large volume of data exists, empirically selected distributions could provide a marginally better fit.
LOW FREQUENCY OSCILLATIONS ON THE DUTCH COAST
Authors: Gerritsen F. , Van Heteren J.
Published: June 2019

During several months in 1981 and 1982/1983 two extensive programs of field measurements were carried out at Egmond on the Dutch North Sea coast, one during the spring of 1981 and the other during the winter of 1982/83. In these programs researchers of the Dutch "Rijkswaterstaat", of The Delft University of Technology and of the Delft Hydraulics Laboratory cooperated in the planning and execution of the measurements and are now involved in data analysis and evaluation of results. During the year 1983 the senior author spent a sabbatical year with the Rijkswaterstaat in the Netherlands and joined the team effort in analyzing the data. Reference is made to other papers presented at this conference, highlighting some aspect of this research program: Van Heteren and Stive (1984), Derks and Stive (1984). The present paper deals with low frequency oscillations in the surfzone and their potential impact on certain aspects of coastal morphology. The conclusions of this paper have to be considered as tentative and should be followed by further study. Its main intention is to point to certain possible relationships regarding coastal morphology so that in future measurements the program can be designed in such a way that certain relationships can clearly and unmistakenly be identified. The programs of measurements carried out in 1981 and 1982/83 were primarily designed to evaluate the usefulness and accuracy of various types of instruments in the surfzone. The measurements were never designed for the use we have made of them and results may therefore not be fully conclusive and thus subject to discussion. Nevertheless the authors found their tentative findings of sufficient interest to share them with their colleagues.
CALIBRATION AND VERIFICATION OF A DISSIPATION MODEL FOR RANDOM BREAKING WAVES
Authors: Battjes J.A. , Stive M.J.F.
Published: June 2019

A model describing the average rate of energy dissipation in random waves breaking in shallow water, published previously by the first author and Janssen (1978), has been applied to an extensive set of data for the purposes of calibration and verification. Both laboratory and field data were used, obtained on beaches with a more or less plane slope as well as on barred beaches, and for a wide range of wave conditions. Optimal values have been estimated for an adjustable breaking waveheight-coefficient in the model; these appear to vary slightly but systematically with the incident wave steepness, in a range which is physically realistic. A parameterization of this dependence allows the use of the model for prediction. Applied to the present data set, the correlation coefficient between measured and predicted rms wave heights is 0.98, with an rms normalized error of 6% and a bias which does not differ significantly from zero.
PREDICTION OF WAVE GROUP STATISTICS
Authors: Elgar Steve , Guza R.T. , Seymour R.J.
Published: June 2019

Two methods of numerically simulating random seas, given a target power spectrum, are discussed. Wave group statistics, such as the mean length of runs of high waves, produced by the different simulation schemes are compared. For a large number of spectral components, no significant differences are found in the wave group statistics produced by the two simulation techniques. Using the simulation techniques, it is shown that ocean gravity wave group statistics are not inconsistent with an underlying wave field composed of linearly superposed random waves. The majority of the field data examined were collected in 9-10 m depth, significant wave heights ranged from about 20 to 200 cm, and the spectral shapes ranged from fairly narrow to broad. For the 9-10 m depth data, observed mean run length, variance of run length, and the probabilities of runs of a given number of high waves were statistically consistent with the linear simulations. In contrast to the apparent linear behavior in 9-3 0 m depth, waves in 2-3 m depth showed substantial departures from the linear simulations.
ESTIMATES OF LONG WAVES IN THE WESER ESTUARY
Authors: Barthel V. , Funke E.R.
Published: June 2019

Long waves of small amplitudes can excite harbour oscillations as well as the motion of floating structures or vessels. Field data from the Weser Estuary, German Bight of the North Sea were analysed with respect to waves with periods greater than 8 s. After preprocessing of the mostly noisy data records, special analysis incorporated the reconstruction of incorrectly recorded frequency components below .03 Hz and bivariate distributions of heights and periods. Results suggest that long wave activity increases towards the inner estuary. Grouping properties are dependent on wind direction and on directionality of the sea state. Further investigations and model studies for the response of travelling vessels to this wave climate are recommended.
SHOALING PROPERTIES OF BOUNDED LONG WAVES
Authors: Mansard E.P.D. , Barthel V.
Published: June 2019

Group bounded long waves which appear as a set-down under a group of high waves and a set-up in between groups are well described for constant water depth. However, their propagation into shallow water and their interaction with the constituent wave groups are not well understood and theoretically described yet. Therefore, model investigations were carried out to study shoaling properties of these second order waves in terms of amplitudes and phases. The tests give a good insight into the phenomenon and suggest distinct shoaling properties. Moreover, experimental results provide a valuable basis for future theoretical considerations.
A THREE-DIMENSIONAL MODEL OF THE BEAUFORT SEA
Authors: Liu Shiao-Kung , Leendertse Jan J.
Published: June 2019

The Beaufort Sea borders the northern coasts of the United States and Canada. During the last decade, oil discovered at the Prudhoe Bay field contributes a substantial amount of the petroleum needs of the U.S. At present, it represents approximately 20 percent of the total domestic production. However, according to estimates made by the Department of the Interior, gas and oil lie under the Alaskan coastal waters (mainly in the Beaufort Sea) accounts for about 40 percent of the total domestic reserve. To assist government agencies in their assessment of offshore oil exploration, the authors have been engaged, during the past nine years, in three-dimensional modeling work of the the Alaskan coastal area (Fig. 1). Results from the modeling work involving the Bering Sea and the Chukchi Sea have been reported at an earlier conference (Ref. 1). This paper describes the formulation, coupling, and other essential aspects of the Beaufort Sea model (Fig. 2). The Beaufort Sea, occupying a larger portion of the Alaskan coastal water, is dynamically interactive with other modeled areas. Most importantly, the exchange of water mass with the Chukchi Sea interconnects the Bering Sea through the Bering Strait (Fig. 3). Under certain weather conditions, ice in the Beaufort Sea can be transported toward the Bering Sea by an "ice breakout" process through the Bering Strait.
MODEL HARBOUR SEICHING COMPARED TO PROTOTYPE DATA
Authors: Botes W.A.M. , Russell K.S. , Huizinga P.
Published: June 2019

Since 1978 a finite-difference numerical model based on that developed by Leendertse and adapted for resonance studies (Russell and Huizinga, 1978) has been applied to investigate harbour resonance in Table Bay Harbour and several other South African ports. During April 1981 three long-wave recorders were installed in the cooling water intake basin of the Koeberg Nuclear Power Station to determine the occurrence and magnitude of the long waves and to measure the corresponding response of the basin. Koeberg is situated on the west coast of South Africa, 30 km north of Cape Town and is exposed to the approaching cyclonic weather systems which experience has shown to be associated with the occurrence of long waves. An example of an approaching low pressure system with the location of Koeberg is shown in Figure 1.
BOUNDARY CONDITIONS FOR LIMITED AREA MODELING
Authors: Sheng Y.P. , Butler H. Lee
Published: June 2019

A simple open boundary condition for limiting the computational domain in tidal simulations is presented. In modeling the impact of proposed coastal projects with a limited-area model, problems due to undesired reflection of gravity waves at open boundaries often occur. The boundary condition presented herein eliminates these problems in many instances and can be easily incorporated into a wide variety of models. The adapted procedure permits representation of appropriate forcing conditions while allowing propagation of internally-generated disturbances out of the open boundaries. Applications to real world engineering problems are presented.
IS SURF BEAT FORCED OR FREE?
Authors: Huntley David A. , Kim Chang S.
Published: June 2019

Although many field experiments have shown that surf beat motion, with periods longer than incident wave periods, becomes the dominant feature of the nearshore velocity field as the shoreline is approached, the nature of this motion is still not fully understood. This paper describes a field experiment on a sheltered beach which was designed to distinguish between long wave motion directly forced by the incident wave envelope (as suggested by Longuet-Higgins and Stewart, 1962), and wave motion which is only weakly coupled to the local incident waves and therefore essentially free. The results for on/offshore flows show that low frequency surf beat (frequency less than 0.03 Hz) is strongly correlated with the wave envelope, suggesting the dominance of forced wave motion at these frequencies. In a higher frequency band, between 0.06 and 0.095 Hz, the correlation is generally much lower, suggesting that free wave motion, possibly subharmonic edge waves, is significant in this band. The longshore flows are much more weakly correlated to the envelope of either the longshore or on/offshore components of the orbital velocity. This is consistent with previous observations that edge wave motion dominates the longshore surf beat motion.
EXTREME SEA LEVELS ON THE COAST OF CALIFORNIA
Authors: Flick Reinhard E. , Cayan Daniel R.
Published: June 2019

During the winter of 1982-1983, a combination of high tides, higher than normal sea level and storm-induced waves were devastating to the coast of California. Damage estimates for public and private property destruction in the coastal counties of California total over $100,000,000. Much higher than average sea levels played a very important contributory role in the flooding damage. This report describes and examines the oceanographic and meteorological conditions prevailing during winter 1982-1983, and attempts to put them into perspective using historical information at San Diego. Emphasis is placed on the processes and forces that contribute to extreme sea levels in the hope that better understanding of these and more complete information on historical extremes will help the engineer in design and in assessment of risk. The unusually high sea levels were due to a combination of higher than normal mixed layer temperature associated with a strong, 2-year El Nino, storm surge due to low atmospheric pressure and persistent onshore winds, and the cumulative effect of steady, "global" rise in relative sea level. Higher than average high tides coincided to an unusual extent with the peak sea levels reached during the numerous storms between November 1982 and March 1983. Important cyclical variations occur in California's tide regime and the consequences of these on extreme tides have not been considered previously.
NEW ASPECTS CONCERNING THE INCREASE OF SEA LEVEL ON THE GERMAN NORTH SEA COAST
Authors: Rohde Hans
Published: June 2019

The development of MThw on the German North Sea coast is probably related to the development of the climate. Other important contributing factors are discussed. For the last 20 years a relatively steep rise of MThw level is recognizable. An even steeper rise as a result of climate changes appears possible within the next 100 years. With regard to the great importance for coastal engineering, the necessity of attentive observation and international cooperation among different scientific disciplines is stressed.
EXPLICIT SOLUTIONS TO PRACTICAL WAVE PROBLEMS
Authors: Nielsen Peter
Published: June 2019

Explicit formulae are provided for wave problems covered by linear wave theory. Two goals are pursued. The first is to provide a faster and more flexible tool than usual wave tables. The second is to provide explicit, analytical solutions to problems that have so far demanded time consuming numerical integrations. As an example we solve the problem of wave height variation due to refraction, shoaling and energy dissipation over a soft mud bottom. The obtained explicit solutions are accurate enough for practical purposes and require very little computational effort, in fact they will enable the engineer to solve many wave problems with a handheld calculator. Another advantage of analytical solutions is that they are always much more instructive than numerical results.
COMBINED REFRACTION-DIFFRACTION OF NONLINEAR WAVES IN SHALLOW WATER
Authors: Kirby James T. , Liu Philip L.F. , Yoon Sung B. , Dalrymple Robert A.
Published: June 2019

The parabolic approximation is developed to study the combined refraction/diffraction of weakly nonlinear shallow water waves. Two methods of approach are taken. In the first method Boussinesq equations are used to derive evolution equations for spectral wave components in a slowly varying two-dimensional domain. The second method modifies the equation of Kadomtsev s Petviashvili to include varying depth in two dimensions. Comparisons are made between present numerical results, experimental data and previous numerical calculations.
PROFILE ASYMMETRY OF SHOALING WAVES ON A MILD SLOPE
Authors: Hwang Paul A.
Published: June 2019

From limited experimental evidence, shoaling monochromatic waves seem to possess certain similarities. Specifically, the harmonic composition follows the trend of solitary or cnoidal waves, and the phase difference of harmonics vary with water depth monotonically. Based on the above observation a similarity model is constructed to study the asymmetric properties of shoaling waves. The implication of wave asymmetry on wave breaking is discussed.
MODELING TURBULENT BORE PROPAGATION IN THE SURF ZONE
Authors: Basco David R. , Svendsen Ib A.
Published: June 2019

Initial efforts to numerically simulate surf zone waves by using a modified form of the nonlinear shallow water equations are described. Turbulence generated at the front of the moving bore-like wave spreads vertically downward to significantly alter the velocity profile and hence the horizontal momentum flux. This influence of turbulence is incorporated into the momentum balance equation through a momentum correction coefficient, a which is prescribed based in part upon the theoretical a(x) distribution beneath stationary hydraulic jumps. The numerical results show that with a suitably chosen a(x) distribution, the equations not only dissipate energy as the waves propagate, but also that the wave shape stabilizes as a realistic profile rather than progressively steepening as when the nonlinear shallow water equations are employed. Further research is needed to theoretically determine the appropriate a(x,t) distribution.
A NUMERICAL SOLUTION OF BOUSSINESQ TYPE WAVE EQUATIONS
Authors: Schaper H. , Sielke W.
Published: June 2019

Numerical models of short waves in shallow water, which are of particular interest for the calculation of the wave climate in harbours and coastal areas, have been presented by Abbott et al. (1978) and by Hauguel (1980). These models are based on the solution of the Boussinesq or Serre type equations. A recent discussion of the range of application for the equations has been presented by McCowan (1982). Nevertheless, there is some uncertainty as to which terms in the differential equations are of importance, and how they are to be approximated. Therefore, no final judgement can presently be made on the accuracy and credibility of the solutions. Research on such models is still in progress and is of high theoretical and practical interest. Some of the aspects of current research relate to the handling of nonlinear terms, the non-reflecting boundary conditions and the transfer capability of the models for spectral input. This paper will reflect on these points.
INTERACTION OF NON-UNIFORM CURRENTS AND SURFACE HAVES
Authors: Ismail Nabil M.
Published: June 2019

Modifications of surface gravity waves and opposing nonuniform currents due to their interaction in coastal waters were experimentally and theoretically investigated. The flow field is modelled as a steady turbulent jet heads directly into the surface waves. Experimental results show that the net waves momentum flux is decreased as waves propagate into the jet which gives rise to mean water set-up towards the jet source. Opposing waves increase the spreading rate of the jet and causes vertical upwelling of the mean flow, near the bottom, towards the free surface. Theoretical predictions of the increase of the jet spreading rate and wave set-up agree with the experimental data. Wave-current interaction modifies significantly waves bottom flow pattern by focusing ambient nearshore waters on the jet outlet.
A NUMERICAL MODEL FOR REFRACTION OF LINEAR AND CNOIDAL WAVES
Authors: Headland John R. , Chu Hsiao-Ling
Published: June 2019

A numerical model for refraction of linear and cnoidal waves over an arbitrary bottom is presented. The model, which is based on the ray theory of refraction (11), utilizes linear theory in deep and intermediate water and cnoidal theory in shallow water. The model permits one to determine nearshore wave properties using a nonlinear wave theory. Nearshore wave properties such as wave height, celerity, and wave angle determined using the linear-cnoidal refraction model may vary considerably from those determined using a linear refraction model. In general, cnoidal waves refract less, travel faster, and shoal higher than linear waves. This result can have a considerable effect on coastal engineering design, particularly in the areas of coastal structure design and longshore transport computations.
EFFECTS OF OPPOSING CURRENT ON WAVE TRANSFORMATION ON SLOPING SEA BED
Authors: Sakai Shigeki , Saeki Kiroshi
Published: June 2019

The transformation and the breaking of waves affected by an opposing current on the sloping sea bed were discussed. It was found that the characteristics of wave transformation before breaking point can be determined by the deep water wave steepness and the dimensionless unit width discharge. Concerning the wave decaying due to breaking, the characteristics of the change in the wave height depend only on the slope of the sea bed. Fourth order solutions of Stokes wave on a uniform current were calculated based on the first and second definition of the wave celerity, respectively. The theoretical solutions for wave transformation by the energy flux method were presented. Comparisons between the theoretical solutions and the experimental results gave the criteria of the applicability of our solutions corresponding to the dimensionless unit width discharge. In the calculation of energy flux, it was pointed out that the change in the mean level of the free surface should be taken into account. It was made clear that the change in the mean level of the free surface can be evaluated by Bernoulli's equation, and the energy flux in which the change in the mean level of the free surface was taken into account was proposed. The criteria of breaking corresponding to the dimensionless unit width discharge were clarified, experimentally.
EXTREMAL STATISTICS OF STORM SURGES BY TYPHOON
Authors: Tsuchiya Yoshito , Kawata Yoshiaki
Published: June 2019

The objective of this paper is to propose a new approach based on the direction of the typhoon track for determining the probability of occurrence of extremal tides due to storm surges, as well as their return period. The study includes the effects of periods in tidal data and of tidal variation stemming from extensive reclamation along coasts on the fitness of the extremal data to probability density functions. The method is justified by application to an analysis of the probability of occurrence of storm surges in Osaka bay.
CONPORMAL MAPPING SOLUTION OP A WAVE FIELD ON THE ARBITRARILY SHAPED SEA BOTTOM
Authors: Nadaoka Kazuo , Hino Mikio
Published: June 2019

A new wave equation has been derived for the full nonlinear dispersive waves propagating over an arbitrarily shaped sea bed. The method of the derivation of the equation uses a conformal mapping technique by which the original domain can be transformed onto a domain with a uniform depth to make the basic equation easily integrable vertically. By taking an inverse Fourier transform, the velocity potential obtained by the integration can be expressed in the form which can construct the exact wave equation from the water surface boundary conditions. An algorithm for the numerical integration of the equation is presented with some examples of the solution.
A FINITE ELEMENT METHOD FOR STORM SURGE AND TIDAL COMPUTATION
Authors: Coeffe Y. , Dal Secco S. , Esposito P. , Latteux B.
Published: June 2019

The paper reports the current progress in developing a finite element method for the shallow water equations. Some recent developments as the implementation of a semi implicit scheme or the use of an incident wave condition are described. Different realistic applications are presented concerning tidal and storm surge simulations.
FLUCTUATIONS IN LITTORAL DRIFT
Authors: Silvester Richard
Published: June 2019

The long assumed uniform movement of sand along the coast produced by wave action can be disputed when the interaction of storm sequences and swell is considered. Storm waves form a protective bar, which essentially puts material back into circulation for the oblique swell to work upon. The resulting longshore transport is swift whilst the bar exists but decreases to negligible proportions once it is denuded and the normal swell-built beach profile recurs. This impulsive drift has many implications for engineers and geomorphologists and to researchers attempting to predict annual rates of transport.
A LABORATORY EXPERIMENT OF BEACH CUSPS
Authors: Kaneko Arata
Published: June 2019

Beach cusps with a longshore spacing of 20 to 150 cm have been built by the continuous action of incident waves on a steep laboratory beach. In the formation stage of beach cusps, all bed materials on the beach moved shoreward. The backwash vortex, which was found first by Matsunaga and Honji (16,18) on a laboratory beach, gave a good explanation of the shoreward movement of bed materials. Beach cusps formed when the value of a dimensionless parameter H^Lk/h^L, which controls swash motion on a steep beach, became larger than 1.12; H)-, is the height of the breaking wave, Ljj its wavelength, h^ the water depth at the breaking point and L the horizontal distance from the shoreline for still water level to the breaking point. The observational spacing of beach cusps formed regularly were in quite good agreement with half a wavelength of the zero-mode subharmonic edge wave generated on a sloping flat beach. As a result of this study, the contribution of edge waves on cusp formation becomes more undoubted.
STABILITY OF MULTIPLE INLETS
Authors: Krueger Jacobus van de Kreeke
Published: June 2019

A computational framework is presented to evaluate the stability of two inlets connecting the same bay to the ocean. It is assumed that both inlets are scoured in alluvial material. The main ingredients in the stability analysis are the closure surface and the equilibrium stress surface. The closure surface of an inlet is defined as the relation between the tidal maximum of the bottom stess and the cross-sectional areas of both inlets. The equilibrium stress surface of an inlet is the relation between the tidal maximum of the bottom stress and the cross-sectional area of that inlet at the time the inlet is in equilibrium with its hydraulic environment. The method is applied to Pass Cavallo and the entrance to the Matagorda Shipping channel further referred to as Matagorda Inlet. Both inlets connect Matagorda bay to the Gulf of Mexico.
SEDIMENT DYNAMICS FIELD EXPERIMENT: SUNDAY'S RIVER
Authors: Swart D.H.
Published: June 2019

A field exercise was performed on a high-energy beach east of the Sunday's River in Algoa Bay on the east coast of the Republic of South Africa in the latter half of April 1983. Recorded data include nearly continuous wave data at 7 stations within the breaker zone with simultaneous waverider recordings in a water depth of 10 m, suspended sediment data gathered by means of 'bamboo' poles and instantaneous bottle samplers, daily topographical measurements of the beach and inshore area, data on rip current intensity and spacing for a 10 km coastal strip, more than 3 000 bottom sediment sample analyses and visual observations of wave height and longshore current velocity at hourly intervals through the recording period. Analysis of the data has been completed and interpretation and correlation of various measured phenomena are underway. A second exercise was performed in August 1984, when the emphasis was on nearshore circulation patterns.
SCALE-MODEL RELATIONSHIP OF BEACH PROFILE
Authors: Ito Masahiro , Tsuchiya Yoshito
Published: June 2019

This paper presents a scale-model relationship for the similarity between large and small scale-models in two-dimensional equilibrium beach profiles. Taking large scale-models using large scale equipment as prototypes, the experimental scale of a medium-sized model was gradually varied keeping the grain size ratio of model to prototype constant. A similarity-comparison between large and small scale beach profiles is made by considering the degree of experimental errors. Judgement results are graphically shown, and a scale-model relationship is proposed. It is found that the scale-model relationship proposed agrees with the ones derived from the empirical formulae expressing the properties of beach profiles. Additionally, the applicability of this scale-model relationship to the reproduction test of natural beaches is examined.
A SYSTEM OF MATHEMATICAL MODELS FOR THE SIMULATION OF MORPHOLOGICAL PROCESSES IN THE COASTAL AREA
Authors: Boer S. , De Vriend H.J. , Wind H.G.
Published: June 2019

A compound mathematical model (COMOR) for the simulation of morphological changes in the coastal area is being developed. The model is very flexible; it can be composed according to the specific demands of the problem which is considered. So far the model is being applied in the advisory practice to predict initial morphological changes. Recent experiences have shown that the model is quite useful, although at present the knowledge of the individual coastal processes and their interactions is still insufficient to utilize it optimally. However, it is foreseen that in the near future such mathematical models will become a powerful tool in coastal engineering.
A SIMPLIFIED MODEL FOR LONGSHORE SEDIMENT TRANSPORT
Authors: Bailard James A.
Published: June 2019

An energetics-based longshore sediment transport model is developed which takes the form of a modification to the wave power equation. Instead of being constant, the wave power coefficient is a function of the breaker angle and the ratio of the orbital velocity magnitude and the sediment fall velocity. This modification extends the range of application of the wave power equation to include both field and laboratory conditions.
Complete Proceedings - Single PDF Download
Authors: Edge Billy L.
Published: June 2019

Solving engineering problems associated with coastal and offshore areas is one of the most important environmental challenges we face. The many natural resources in these regions require careful management based on sound scientific and technical information. Over 200 papers are included in this publication providing in depth state-of-the-art reviews, and current research and practices in coastal engineering. The five main divisions of coastal engineering presented here are: (1) Theoretical and observed wave characteristics; (2) coastal processes and sediment transport; (3) coastal structures and related problems; (4) coastal, estuarine and environmental problems; and (5) ship motions.
MAXIMUM ENTROPY SPECTRAL ESTIMATION FOR WIND WAVES
Authors: Alverez Jorge Calderon , Loureiro Adolfo Maron
Published: June 2019

Some results are presented on the application of new spectral estimation techniques using AR and ARMA models, also known as Maximum Entropy- Methods, to wind wave spectral analysis. The results are compared with those obtained with conventional FFT methods. The application of some mathematical methods for model order selection is included. The relation between the optimum order and different spectral parameters is investigated.
ANOTHER APPROACH TO LONGSHORE CURRENT EVALUATION
Authors: Losada M.A. , Sanchez-Archilla A. , Vidal C.
Published: June 2019

A simple model to predict the longshore current velocity at the breaker line on a beach with oblique wave incidence, is presented. The model balances driving and resistance terms (gradients of radiation and turbulent Reynolds stresses and bottom friction) to get a general expression for the velocity. This equation shows explicitely the influence of Iribarren's parameter on longshore current generation. It has been tested with field and laboratory data, obtaining a reasonable fit to measured values. The resulting (predictive) model is expected to be valid for any type of breakers though the calibration has been mainly done for spilling and plunging types, due to the scarcity of results for other breakers.
PREDICTION OF PROPERTIES OF MARINE SAND BY IN-SITU MEASUREMENT OF WAVE INDUCE PORE PRESSURE
Authors: Maeno Yoshihiko , Hasegawa Takashi
Published: June 2019

The purpose of this paper is to predict the physical and mechanical properties of deposits near the surface of the seabed by in-situ measurements of the wave-induced pore pressure. First, the wave-induced pressure both at the surface of the seabed and inside the seabed are examined by frequency analysis, to clarify the propagation characteristics of pressure in the seabed. Secondly, a theoretical equation which gives the relationship between pore pressure fluctuation and wave pressure fluctuation is proposed. Thirdly, the porosity of the seabed is predicted by the propagating characteristics of the pore pressure within the seabed based on the results of both the model tests by wave tank and the field measurements of the wave-induced pore pressure. Finally, by fitting the theoretical equation to the spectral ratio of the in-situ measured pore pressure fluctuation to wave pressure fluctuation, the bulk modulus of the seabed and the degree of saturation are predicted.
LABORATORY STUDY ON TWO-DIMENSIONAL BEACH TRANSFORMATION DUE TO IRREGULAR WAVES
Authors: Mimura Nubuo , Otsuka Yukinori , Watanabe Akira
Published: June 2019

In the present study, effects of irregular waves on two-dimensional beach transformation and related phenomena were investigated through a series of laboratory experiments. Attempts were made to determine a representative wave of irregular wave trains which controlled individual phenomenon related to the two-dimensional beach profile change. It was found that the representative wave is different for each phenomenon. For the macroscopic beach profile change, it is the mean wave which represents whole incident waves. On the other hand, some of microscopic phenomena, such as initiation of sand movement and sand ripple formation, are controlled by larger waves in the wave train selectively, of which representative wave is the significant wave.
AN AUTOMATED MEASURING SYSTEM TO REGISTRATE AND BALANCE SUSPENDED SEDIMENT AND ASSOCIATED PARAMETERS
Authors: Neumann Lothar J.R.
Published: June 2019

The automated measuring system Oortkaten (AMO) was established in order to determine the balance of suspended sediment and associated parameters. Morphological and velocity weighted averaged samples are taken using the newly developed MOSTRA-Method. This results in a cross-sectional average value.
LABORATORY STUDY ON SAND TRANSPORT OVER RIPPLES DUE TO ASYMMETRIC OSCILLATORY FLOWS
Authors: Sato Shinji , Horikawa Kiyoshi
Published: June 2019

Mechanism of sand movement due to asymmetric oscillatory flows was investigated through experiments. Measurements of bed forms, suspended sand concentration and net sand transport rate were carried out by using an oscillatory flow tunnel. The process of entrainment and suspension of sand above asymmetric ripples was quantitatively described. The geometry of ripples and the net sand transport rate in regular and irregular flows were expressed in terms of hydraulic parameters characterizing the oscillatory flow. Two-dimensionality of ripples was found to be an important factor in the estimation of the net sand transport rate.
EXTREME WAVE PREDICTION USING DIRECTIONAL DATA
Authors: Deo M.C. , Burrows R.
Published: June 2019

Potential inconsistencies in the predictions of long term wave heights can be experienced as a result of different methods of analysis possible when using directional wave data. This paper attempts to illustrate some of them. It involves analysis of two sets of directional wave data - one froa a coastal location in the Irish Sea and another from an offshore location in the North Sea. An attempt is made to eliminate the discrepancies between the long term return-value wave height predictions based upon the conditional height distributions associa ted with different direction sectors and those derived from the oonl-directional data set.
MODELING TURBULENT BOTTOM BOUNDARY LAYER DYNAMICS
Authors: Sheng Y.P.
Published: June 2019

This paper presents a modeling approach aimed at solving a complete hierarchy of turbulent bottom boundary layers which are often encountered in practical coastal and oceanographic engineering problems. The practical problem is extremely complex due to the presence and interaction of competing processes. A comprehensive model is thus needed to first provide fundamental understanding of a variety of turbulent bottom boundary layers before any simple model for the complex problem can be meaningfully constructed. This paper presents a comprehensive second-order closure model of turbulent transport and in addition, discusses some applications of the model to wave boundary layer, wave-current boundary layer, sediment-laden boundary layer and two-dimensional boundary layer. Example is provided to show how such a comprehensive model may be used to guide the development of a simple model.
BEACH CHANGE AROUND DETACHED BREAKWATERS DUE TO ARTIFICIAL NOURISHMENT OF BYPASSED SAND
Authors: Suyama H. , Uda T. , Yoshimura T.
Published: June 2019

Field experiment of sand bypassing was conducted on the Shimoni-ikawa Coast in Toyama Bay. The materials of 5900 m3 dredged on the updrift coast of the harbor were thrown into behind the detached breakwater. After the nourishment detailed surveys of the bottom topography around the breakwaters, wave observations and tracer tests using colored concrete blocks were carried out in order to investigate the movement of the nourished sand. Temporal and spatial changes of the shoreline positions and the sectional area of the beach in the shoreward zone of the detached breakwater are examined. It is found through the field experiment that the materials nourished behind the detached breakwater were carried slowly in the longshore direction by the westward littoral drift, dominating on the coast, without the outflow of sand through the openings of the breakwaters. It is concluded that the detached breakwater is useful to control the on-offshore sand movement and to retain the sand behind the detached breakwater.
SHOALING SURFACE GRAVITY WAVES: A BISPECTRAL ANALYSIS
Authors: Doering J.C. , Bowen A.J.
Published: June 2019

Nonlinearities (wave-wave interactions) play a vital role in many aspects of nearshore dynamics, such as wave shoaling and breaking, wave forces, wave-current interactions, radiation stress effects, and sediment transport. The importance of nonlinearities in the nearshore region cannot be overemphasized. At present, however, there is no wave theory that adequately accounts for these interactions, and field observations are sparse. Herein, the bispectrum is used to investigate the temporal and spatial variation of wave-wave interactions in cross-shore velocity for shoaling surface gravity waves in several nearshore environments. The implications for sediment movement of the sign of the observed wavewave interactions for both the real part of the velocity bispectrum (which is related to the skewness of the horizontal asymmetry) and the imaginary part of the velocity bispectrum (which is related to the skewness of the temporal derivative) are discussed. A parameterization is given for the amplitude and phase evolution of the self-self sum interactions within the wind-wave peak for both planar and barred nearshore topography. The results of this paper underline the potential importance of infragravity wave energy in determining nearshore morphology.
ANALYTICAL RESEARCH OF LITTORAL TRANSPORT RATE AND WAVE ENERGY ALONG THE PUTAI HARBOR SITE
Authors: Wang T.J. , Lin C.S. , Hou H.S.
Published: June 2019

Due to the sheltering effect of the Wai-San-Ding Sand Barrier, the hydraulic condition of the putia harbor site is quite favorable. Since the relatively well-protected location of the Putai harbor area with regard to both waves and wind, no special navigational problems have to be envisaged. The wave energy of the Putai harbor site is computed from the measured waves by considering the refraction effect down to breaking line. As the lack of wave records, the wind speed is used by applying the regression equations among the wave height, period and wind speeds, and then compute the wave height and period for obtaining the breaking wave energy. Therefore the total breaking wave energy (P# ) of the whole year along the Putai harbor coast is summated. The littoral transport rate { IJ ) is calculated from the mesh method by comparing the echo-sounding maps of two continuous different years. Therefore, the relationship of PJ and 1/ is correlated in the Putai harbor site.
WAVE AND CURRENT INTERACTIONS IN SHALLOW WATER
Authors: Yoon Sung B. , Liu Philip L.F.
Published: June 2019

Interactions between waves and currents are common and important phenomena in the coastal zone. Coastal currents, such as longshore currents, rip currents, and river flows, can significantly change wave heights and directions of wave propagation. Consequently, the design for shoreline protection measures must be adjusted accordingly. Various theories for wave-current interactions exist and have been reviewed by Peregrine and Jonsson (1983). Most of these theories are developed for large-scale currents where the length-scale for the current variation is much greater than the typical wavelength. These theories cannot be applied to the coastal currents which are small-scale currents. In this paper, the interactions between currents and nonlinear shallow water waves are investigated. Boussinesq equations are used to derive evolution equations for spectral wave components. The current intensity is assumed to be larger than the leading wave orbital velocity and smaller than the group velocity. The length-scale of the current is much shorter than those assumed in the existing large-scale theories. To facilitate numerical computations, the parabolic approximation is applied and a simplified model is developed. A numerical example is given for the refraction and diffraction of cnoidal waves over a rip current on a sloping topography. Both normal and oblique incident cases are examined.
WAVE TRANSMISSION ACROSS SUBMERGED NEAR-SURFACE BREAKWATERS
Authors: Adams Clark B. , Sonu Choule J.
Published: June 2019

Wave transmission across a submerged breakwater at Santa Monica, California, is examined through a three-dimensional model test. The results agree with empirical criteria previously proposed by Tanaka (1976).
DURABILITY OF ROCK ARMOUR ON COASTAL STRUCTURES
Authors: Bradbury A.P. , Allsop N.W.H.
Published: June 2019

This paper summarises many of the recent advances in the testing of rock quality for coastal structures. Advanced work on armour profile and armour unit shape descriptors is identified. A set of assessment methods for monitoring armoured slopes in the field are described, with examples drawn from recent monitoring exercises. The paper concludes by describing future directions of research in this field.
ULTIMATE RESISTANCE OF VERTICAL PLATE ANCHORS IN CLAY
Authors: Das Braja M. , Picorness Miguel
Published: June 2019

Laboratory model test results for the ultimate pullout resistance of vertical square anchors embedded in saturated or near saturated clay have been presented. The undrained shear strength of the clay and the embedment ratio of the anchors have been varied. Based on the model test results, an empirical parametric relationship for estimation of the ultimate pullout resistance of shallow and deep square anchors has been presented.
THE DESIGN OF A SLOTTED VERTICAL SCREEN BREAKWATER
Authors: Gardner J.D. , Townend I.H. , Fleming C.A.
Published: June 2019

This paper describes Che wave studies, model testing and structural design of a 250 metre long slotted vertical screen breakwater for a marina at Plymouth, England. The marina is being developed by Plymouth City Council to provide a purpose built facility for hosting the major long distance races that start or finish at Plymouth, in addition to the usual marina facilities for private boat owners. After examining three alternative locations Plymouth Council selected a site in the north-east corner of Plymouth Sound as shown in Figure 1. The site is confined on two sides by existing shipping channels and by a rocky shore on the land side. Exposure to wave attack is limited to the south west sector. Because the existing seabed at the marine site was the responsibility of the Duchy of Cornwall, an Act of Parliament was required before Plymouth Council could commence construction. The Act contains clauses regulating the use of the marina and the permissable changes to the wave conditions in the adjacent shipping channels.
STUDIES ON FIXED RECTANGULAR SURFACE BARRIER AGAINST SHORT WAVES
Authors: Hwang Ching-Her , Tang Frederick L.W.
Published: June 2019

In short waves, the particle motion in deeper region are to be negligible. For rigid vertical breakwaters built in considerable deep water, the lower part of vertical wall does not play the vital role of wave defending. It can be replaced by a frame to support the surface barrier which bears the wave force, and remain vacancy of the lower part of breakwater. Hence the theoretical and experimental characteristics of wave transmission and spectra alternation are investigated respectively here for this kind of the fixed, rigid, rectangular surface barrier in order to obtain an economic section and verify its capable relative depth as the design basis of deep port breakwater.
PREDICTION OF WAVE RUNUP AND RIPRAP STABILITY
Authors: Kobayashi Nobuhisa , Greenwalk Jeffrey H.
Published: June 2019

A numerical model has been developed to predict the wave motion on a rough impermeable slope and the hydraulic stability and sliding motion of armor units under the action of a specified normally incident wave train. The developed numerical model has been compared with riprap test results to calibrate and verify the model.
ON THE SCATTERING OF CONCRETE ARMOUR UNITS OF DETACHED BREAKWATERS DUE TO WAVES
Authors: Kohno H. , Uda T. , Yabusaki Y.
Published: June 2019

On the Fuji Coast 15 detached breakwaters and 17 wave dissipating breakwaters have been constructed to prevent beach erosion. By virtue of the construction of the breakwaters the retreat rate of the shoreline position has decreased. However a large number of concrete blocks have been scattered due to waves. This study investigates the actual circumstances on the scattering of the concrete armour units of the detached breakwaters through the field observations on the Fuji Coast located in Suruga Bay facing the Pacific Ocean. The change rate of the plane area of the breakwater is examined from the aerial photographs, and the relationships among the parameter, the depth at the offshore foot of the breakwater and the number of the removed concrete armour units are investigated.