bluuebunny/crossref_metadata_2025 huggingface dataset:
MEASUREMENTS OF FORCES ON DOLOS ARMOR UNITS AT PROTOTYPE SCALE
Authors: Howell Gary L.
Published: June 2019

In-situ measurements of the structural bending moments and torque about the shank-fluke interface of the dolos armor unit have been made for 42-ton (36-metric tonne) dolosse at Crescent City, California jetty. The measurements include the static loads on the dolosse as well as wave induced forces. The data were obtained from internal strain gages cast into the dolos during construction along with a special data acquisition system. The measurement system was also capable of capturing impact forces caused by dolos rocking or movement. Measurements were made during the winter storm seasons from January 1987 through May 1988. Coincident with the structural measurements, wave height and period were measured at several water depths approaching the breakwater, including a site directly in front of the dolos test section. The Crescent City jetty is a shallow water breakwater with depth limited waves in about 10 meters of water depth. The structural measurements were made from 14 dolos units arranged in a rectangular section on the top layer of the trunk portion of the jetty. Four of these dolosse are also instrumented with an accelerometer platform to measure motion with six degrees of freedom. In addition, there are three instrumented dolosse on the bottom layer of the breakwater. These dolosse measure the static stress due to the units placed on top of them, as well as pulsating forces. The structural and wave measurements, reported here, are supplemented with hydrostatic pore pressure measurements in the core material of the breakwater, and by aerial photogrammetric motion analysis (Kendall, 1988), land based surveys, boudary condition surveys, hydrographic surveys, and side scan sonar surveys.
"DOUBLE U BLOCK" AND "IBLOCK" - THE ARMOUR BLOCKS OF TWO NEW TYPES
Authors: Twu S.W. , Lin S.C. , Chang S.G.
Published: June 2019

A total of eleven new types of blocks are developed for this project. After performing a series of model tests for them and having a consideration of easy casting, two types of blocks are selected and presented here in this paper. They are named "Double U block" and "I block", respectively. The two have been compared with several existing types which have been widely used in Taiwan. It is shown that the Double U block is an excellent type of block with high stability and low reflection coefficient. The I block has an advantage of easy casting, although it is not outstanding in other characteristics.
ARTICULATED CONCRETE MAT SLOPE PROTECTION
Authors: Leidersdorf Craig B. , Gadd Peter E. , McDougal William G.
Published: June 2019

This paper provides guidance for the design, fabrication, and installation of articulated concrete mat slope protection. Although articulated mat armor has been utilized for many years in low-energy wave environments, it has been extended recently to accommodate intermediate wave energies and severe ice loads. The development of the concept is discussed, after which hydraulic design considerations, material design considerations, and fabrication and installation techniques are presented. Prototype performance is reviewed. It is concluded that articulated concrete mat armor is capable of providing effective slope protection in intermediate-energy wave environments, and that additional research is required relating to hydraulic stability and failure modes under wave and ice loading.
SIMPLIFIED MODELS FOR MEASURING ARMOUR UNIT FORCES
Authors: Scott R.D. , Turcke D.J. , Anglin C.D. , Baird W.F.
Published: June 2019

Damage of concrete armour units on a number of breakwaters around the world has brought into question the design methodology for these structures. The interaction of waves with a rubblemound breakwater is a complex process typified by the random nature of the wave loadings and of the placement and orientation of the armour units. The objective of this paper is to present the development of a more simplistic physical model for establishing a realistic upperbound for the forces occurring on concrete armour units, to more readily understand the response of the unit to various wave parameters, and to explore the effect of carrying out tests at different scales. The results of these investigations demonstrate the applicability of employing simplified models to assist in understanding the response of armour in a breakwater and the consistency of the instrumentation at different scales.
LONG TERM EXPERIENCE WITH SEAWALLS ON AN EXPOSED COAST
Authors: Magoon Orville T. , Pope Joan L. , Sloan Robert L. , Treadwell Donald D.
Published: June 2019

Appropriately designed, constructed, and maintained rubble mound seawalls are an efficient and cost-effective means of protecting erodible sections of exposed coastline. This conclusion is supported by more than 25 years of satisfactory seawall performance along the Pacific Ocean coast of Santa Cruz County, California, U.S.A. Important factors in satisfactory seawall performance include a clear understanding of the oceanographic and geologic design parameters, a vigorous inspection program during construction, and continued observation and maintenance of the structures.
DYNAMIC STUDIES ON CAISSON-TYFE BREAKWATERS
Authors: Ming Gao , Guanying Dai , Jihua Yang
Published: June 2019

In this paper, studies on dynamic characteristics and responses under waves of caisson-type breakwaters by field and model testings as well as dynamic analyses are described. It is found that the gravity-type structure-foundation system can be simplified as a rigid body on a linear or non-linear elastic foundation for evaluating its dynamic characteristics and responses. The dynamic displacements of the caisson are found related to the wave heights, the water depth as well as the foundation soil properties.
DYNAMIC FORCES DUE TO WAVES BREAKING AT VERTICAL COASTAL STRUCTURES
Authors: Partenscky Hans-Werner
Published: June 2019

In the past 20 years, considerable effort has been devoted to replacing the widely used approaches of HIROI, MINIKIN, NAGAI, PLAKIDA and others /1,2,3,4/, for the design of vertical breakwaters under the impact of breaking waves, with improved and more exact calculation methods. However, almost all new theoretical and empirical approaches lacked the support of prototype measurements or test results from model measurements at a larger scale. The difference between the proposed design criteria and classical approaches is sometimes so great that engineers do not have a reliable method for the design of a vertical or composite breakwater. Figure 1 shows the resulting wave forces per unit width due to different theories as a function of the design wave height H.
MIXING OF THERMAL DISCHARGES IN COASTAL WATERS
Authors: Ismail N.M. , Wiegel R.L. , Ryan P.J. , Tu S.W.
Published: June 2019

Mixing of thermal effluents, being discharged from thermal power plants on coastlines and which head into surface waves was investigated by analyzing extensive field and laboratory data on plume and ocean ambient conditions. Emphasis was given on the effect of waves and surf zone currents on the modifications of plume surface area and vertical temperature profile in the near-field area. The results of this investigation showed that large opposing waves increase the plume surface area, in the vicinity of the outfall, for all cases of tide level and wave direction. Moreover, waves focused cold bottom currents on the discharge outlet and consequently the temperature of the released warm water was decreased at the surface and near the bottom. Wave-induced cross flows decreased the plume cumulative surface area which corresponded to fractional excess temperature ranging between 0.8 and 0.5 normalized values. This decrease was shown to be contingent that there is no interaction between the far-field and near-field plume waters. Gradient of wave momentum flux across surf zone was found to be necessary parameter to characterize the incident wave field.
STOCHASTIC ANALYSIS OF OFFSHORE CURRENTS
Authors: Ochi Michel K. , McMillen Richard I.
Published: June 2019

This paper presents the results of stochastic analysis of offshore currents. The purpose of this study is to clarify the stochastic properties of offshore currents, and to develop a method to predict the magnitude of the extreme currents and their direction from measured data. Statistical analysis as well as spectral analysis are carried out on current velocities measured over a period of several months off Newfoundland, Canada. The effect of water depth on the statistical characteristics of current velocity is also clarified. The extreme current velocity expected to occur in 4- months and its direction are estimated by applying order statistics and the results are compared with the measured data.
DEVELOPMENT AND APPLICATION OF A MATHEMATICAL MODEL OF WAVE ACTION ON STEEP SLOPES
Authors: Allsop N.W.H. , Smallman J.V. , Stephens R.V.
Published: June 2019

This paper summaries the initial stages in the development of a mathematical model of wave action on slopes. The model calculates water surface elevation and depth averaged velocity on the slope, and uses this data to estimate the level of wave run-up. The model has been validated by comparing its results with those from similar models, and from a physical model. Examples are presented of these comparisons, which were found to be in good agreement in most cases.
A MODELING SYSTEM FOR COASTAL OIL SPILL RISK ANALYSIS
Authors: Liu Shiao-Kung , Leendertse Jan J.
Published: June 2019

At present, the Prodhoe Bay oil field in Alaska contributes a substantial amount of the domestic oil production of the United States. Oil is also expected to be present on the continental shelf of Alaska, and it is estimated that approximatedly 28 percent of the total U. S. reserve is located beneath the shallow ice covered seas of the Alaskan continental shelf. To expolre and to exploit these oil rich resources, engineers are confronted with hostile oceanographic conditions such as high tides, waves, strong currents and sea ice. The same area is also rich in fishery resources. Being one of the most productive fishing grounds in the nothern Pacific, the potential ecological impact due to an oil spill is of a major concern. This paper describes the methologies used for the development of a modeling system for the oil risk analysis. The system is designed with generality in mind so it can be used for other coastal areas. The development of three dimensional models used in the modeling system described here have been published in the earlier International Coastal Engineering Conferences (Liu and Leendertse, 1982, 1984, 1986) and a report published recently by RAND (Liu and Leendertse, 1987). In the oil-spill risk analysis, these three dimensional hydrodynamic models are coupled to a two-dimensional stochastic weather model and an oil weathering model.
BORE FRONT MODELING IN TERMS OF BURGERS EQUATION AND ITS NUMERICAL CALCULATION METHOD
Authors: Yamashita Takao , Ysuchiya Yoshito , Basco David R.
Published: June 2019

Bore front hydraulics are investigated in terms of Burgers equation to clarify the dynamics of a moving discontinuity in water flow. Burgers equation has been derived from the one dimensional open channel equation with the horizontal turbulent diffusion term. The derived equation system consists of Burgers with respect to dynamic characteristic and hyperbolic equation with respect to water surface elevation, which satisfys Jeffery-Vedernikov condition FT - 2 through discontinuity. It has been verified from the experiments that the condition FT = 2 is a good approximation of bore front dynamics. The numercal calulation method of Burgers equation employing Cole-Hopf transformation and QUICKEST algorithm was also proposed and confirmed its efficiency.
STUDY ON THE VARIATIONS OF AN EUTROPHIC ECOSYSTEM FROM THE SPANISH MEDITERRANEAN LITTORAL: DATA TO HAVE IN MIN IN THE NUTRIENT DUMPING TO THE SEA
Authors: Soler T. E. , Del Rio J.G. , Diez J.J.
Published: June 2019

Cullera Bay is a neritic ecosystem placed on the Spanish Mediterranean Littoral largely influenced by the Jucar River, that brings about lower salinities than surrounding waters, and broad variations of its values. An extensive research, with 9 samplings throughout the year, was carried out, measuring both physical and chemical parameters, and the planktonic communities. The trophic status of the ecosystem, the spatial and temporal variations of the nutrients and the planktonic communities were studied, evaluating the influence of the river loads and the littoral dynamics. Some essential basis to allow a suitable emplacement of waste waters disposals along the Valencian littoral are set up in order to minimize the gradual eutrophication of this coast.
ENGINEERING STUDY FOR A NEW SEAWATER INTAKE SYSTEM
Authors: Edge Billy L. , Schlueter Roger S.
Published: June 2019

Environmental assessment, engineering studies and designs were completed for a new 26.5 m3/s seawater intake system in the Persian Gulf. The original intake facility consisted of a curved, 60m breakwater with one end attached to the shoreline, a settling basin immediately adjacent to the shoreline and dredged to a maximum depth of approximately 5m, and a pumphouse structure located on shore such that the seaward wall formed one side of the settling basin. The facility located on an island in the Gulf, which served multiple seawater uses, had experienced both structural and operational problems, the latter consisting principally of excessive ingestion of sediment and seaweed. These factors plus the requirement for additional demands for seawater beyond plant capacity caused the owner to initiate a study of alternative intake systems, produce a design for the most effective solution and construct the new intake system.
ACCRETION - EROSION IN THE BEACHES OF THE CANARY ISLANDS (SPAIN)
Authors: Martinez Jesus
Published: June 2019

In the beaches under study on the island of Grand Canary, we are identifying and measuring the intertidal annual cyclic processes of accretion and erosion, starting from the topographical movements of the strand. These processes: a) We are analyzing and interpreting these in the framework of the physical and geographical interdependences, and as responses to the more internal evolutions of the morphodynamics, in the sedimentary environments in question, b) and permitting the definition and calculation of some indices of sedimentary gains and losses, of interest to coastal planning and management.
RESULTS FROM THE ATLANTIC CITY, NJ BEACH NOURISHMENT MONITORING PROGRAM
Authors: Sorensen R.M. , Douglass S.L. , Weggel J.R.
Published: June 2019

A beach nourishment project was carried out at Atlantic City, NJ during the summer of 1986. One million cubic yards of sand was dredged from adjacent Absecon Inlet and placed over a 9000 foot long section of the beach. The authors monitored the fill for a period of eighteen months, including two winters, after placement of the fill. This paper briefly summarizes the fill project and monitoring program. Key results of the monitoring program are presented and compared with results of the monitoring program for previous nourishment projects at the site in 1963 and 1970. Differences in the behavior of the 1986 fill vis-a-vis the 1963 and 1970 fills are discussed and possible reasons for these differences are given.
BERM BREAKWATER FAILURE AT ST. PAUL HARBOR, ALASKA
Authors: Weckmann Javier , Watts George M.
Published: June 2019

St. Paul Island, Alaska, is located at 50°10'N latitude and 170°15'W longitude in the south central Bering Sea. It is the most northward and largest island of the Pribilof Island group. The area of the island is about 70 square miles (180 square kilometers), with the city and harbor of St. Paul located at a cove (Village Cove) on the southern coastline. The Pribilof Islands are of volcanic origin and are generally hilly with much of the coastline consisting of precipitous rocky cliffs. Moderate to strong winds are characteristic throughout the year, causing the island to be treeless. It is predominantly covered with grasses, sedges, and wild flowers. The Pribilofs are a natural haven for a variety of flora and fauna. More than a quarter of a million seabirds nest each year along the coastal cliffs. About two-thirds of the world's population of northern fur seals migrate annually to the Pribilofs for mating purposes. The Pribilof Island area of the Bering Sea is also one of the most abundant and richest seafood grounds in the world. Due to a recent moratorium, the harvest of fur seals in the Pribilofs has been discontinued. In order to maintain existing cultural and economic resources, the City of St. Paul has elected to construct a harbor facility at Village Cove to provide services to commercial fishing vessels operating in the central Bering Sea. The maximum natural water depth in the Village Cove area is 26 feet (7.9m) relative to mean lower low tide datum (MLLWO.0). Mean higher high tide level is 3.2 feet (lm) above MLLW, with extreme high tide during storm periods being estimated at between 5.0 and 6.0 feet (1.5 to 1.8m) above MLLW. Waves approaching from the southwest sector have the most effect on St. Paul Harbor. During the winter months, breaking waves with heights of 25 feet (7.6m) and 13-16s periods can be expected at Village Cove several times each year.
TRUNCATION ORDER OF FOURIER WAVE THEORY
Authors: Sobey Rodney J.
Published: June 2019

Specific consideration is given to the dependence of Fourier wave solutions on both truncation order and the number of free surface nodes. Solution dependence is quantified by a comprehensive set of numerical experiments over a typical range of wave height, water depth, truncation order and overspecification values. Integral error measures include the rms free surface boundary condition errors and a slope error that identifies non-physical positive slope segments in the wave profile between crest and trough. Summary error diagrams are presented as a guide to the adoption of suitable truncation orders and overspecification for Fourier solutions. The truncation order is the crucial parameter but there is measurable advantage is some small overspecification.
ARTIFICIAL BEACH UNITS ON LAKE MICHIGAN
Authors: MacIntosh K.J. , Anglin C.D.
Published: June 2019

High water levels on Lake Michigan during 1985 and 1986 created substantial erosion of the shoreline and reduced the size and recreational potential of many of the parks and beaches. To prevent further erosion, protect existing properties and structures, and to create and improve recreational areas along the Lake Michigan shoreline, four coastal engineering projects were designed and constructed during this time. Artificial beach units stabilized by offshore breakwaters were used as the main component of each project. Physical hydraulic model studies were used to determine the orientation, size, and spacing of breakwaters and artificial beach units. Model predictions of beach profiles and plan shapes compare closely with prototype surveys. Surveys completed since construction demonstrate the stability of the beaches and support their use as effective, low maintenance shoreline protection. Prototype experience has shown that these projects are extremely successful both in their ability to withstand storms on the Great Lakes and to attract people for recreational activities.
THE BEACH REHABILITATION PROJECT AT OSTEND-BELGIUM
Authors: Simoen R. , Verslype H. , Vandenbossche D.
Published: June 2019

Steady erosion has occured on the beaches at Ostend, Belgium, especially on the section between the Casino and the Harbour Entrance. The gravel beach supported by a sandfill core has been proven to be a feasible and cost effective flood protection alternative, the first objective of the long term beach enhancement programme. Secondary goals are also met such as : new beach recreational facilities in safe conditions for the public ; the economic incentive for the needed redevelopment of this part of down-town Ostend and the beach front ; the conservation of the present sea-view from the promenade.
AN ENGINEERING STUDY OF OCEAN CITY'S BEACHES, NEW JERSEY, USA
Authors: Weggel J. Richard , Douglass Scott L. , Sorensen Robert M.
Published: June 2019

Ocean City, New Jersey is a major coastal resort in the heavily populated northeastern part of the United States. It is located on a 13 km-long barrier island about 13 km south of Atlantic City and 48 km north of Cape May, the southernmost point in New Jersey. See Figure 1. The barrier island, called Peck's Beach, is bounded on the north by Great Egg Harbor Inlet and on the south by Corsons Inlet. Because wide recreational beaches are important to Ocean City's economy, an engineering study of the beaches was undertaken: a) to quantify natural and man-made shoreline changes, b) to quantify tides, sea level changes, waves, longshore sand transport rates, seasonal variations in beach width and Great Egg Harbor Inlet processes and incorporate them into a sediment budget for Ocean City, c) to determine why past attempts to maintain wide recreational beaches were only partially successful, and d) to recommend a plan to establish and maintain wide beaches.
SHORE PROTECTION OF KAOHSIUNG HARBOR OUTER BREAKWATER
Authors: Kuo Shih-Duenn
Published: June 2019

As shown in Fig.l the main fairway of Port of Kaohsiung is running from north to south with a length of 12 kilometers. To the west, there is a sand bar served as a natural breakwater, the so called outer Breakwater, to provide the port and resident's property the necessary safety and security. Recently, due to rapid growth of container traffic and bulk cargo transportation, Port of Kaohsiung has developed some parts of the outer breakwater near the 2nd Harbor Entrance as Container Terminal No.4 with seven 14-meter-deep, 320-meter-long container berths and about 100 hectares container yard on northern side, and coal Terminal with 16-meter-deep, 320-meter-long berth and a huge storage yard on southern side. Therefore, the shore protection along the area become more and more important year by year. So far, some 6-kilometer seawall and 20 groynes have built successively, and already played a very important role for the shore protection there.
RIA DE FOZ: SOLUTION FOR A HARBOUR AND COASTAL PROBLEM
Authors: Gonzalez Jose Javier Diez , Paredes Victor A. Escobar , Herrando Jose Aguilar
Published: June 2019

The ria of Foz is located in the Northwestern part of the Iberica - Peninsula, inside the Rias Altas group, in the Eastern extrem of Lugo/ province. It is placed on the natural form known as Golfo of Masma, topographical accident that takes its name from the river that flows - into the ria. From the point of view of the materials that constitute the environ ment, they are mainly composed by slaters and quarzites, with some levels of carbonates from the Low Paleozoical period. To the West, the - granitic materials are predominant. The ria is limited in its margens by some little slope and relative ly low cliffs. Its bounds have a little depth, due to the filling process, natural in the Rias Altas. The materials that refill the ria, come from the sea erosion of the cliffs (1), and the refilling is due/ to the sea waves action that produces in the tidal flow and ebb an - - asymetrical capacity of erosion and transport (2). That is a natural - situation, but the human action, building some channeling constructions has accelerated this refilling process. The traditional economic development on this zone, has been based - on some principal activities: fishing and agriculture, but nowadays turistic use rounds off the others. This situation and the evolution - of sailing neccesities on the ria, has been a conflict reason, which - is a consequence of the competition between these uses.
THE FUNDAMENTAL STUDY TO REDUCE THE SETTLED AREA OF THE FISH AGGREGATION DEVICES ON THE SEA FLOOR THROWN FROM A SHIP
Authors: Matsumi Yoshiharu , Seyama Akira
Published: June 2019

This study aims at clarifying the effective method to set up the fish aggregation device (FAD) thrown down from a ship on the designed position most accurately. The numerical simulation technique is developed to analyzed the behavior of the settling FAD in consideration of the effect of vortices generated behind it. From the systematic calculations for the change of the initial condition on the posture of the FAD at throwing, the effective initial posture of the FAD which reduces the settled area on the sea floor most is investigated. Furthermore, the added-mass coefficient of the settling FAD is numerically analyzed from the kinetic energy of the fluid induced by the settling FAD. The FAD treated in this study is the structure to gather fishes.
THE TIME DOMAIN ANALYSIS ON MOORED SHIP MOTIONS
Authors: Kubo Masayoshi , Shimoda Naokatsu , Okamoto Shunsaku
Published: June 2019

The ship refuge inside a harbor in storm requires the analysis of moored ship motions along a quay wall. In this case the time domain analysis with the convolution integral method becomes effective. But the calculation accuracy is not enough and must be improved to analyze actual moored ship motions. In this paper some methods of the improvement are proposed and their efficiency is verified by comparing the calculation results with the experimental ones.
DIRECTIONAL SEA STATE NEAR THE ISLAND OF SYLT
Authors: Schade Daniel , Daemrich Karl-Friedrich
Published: June 2019

In the scope of a joint research program dealing with erosion problems of the island of Sylt in the North Sea, wave measurements with two pitch-and-roll buoys are carried out in order to obtain more detailed information on the sea state with regard to wave dependent morphological processes. The instrumentation is described. Results from the directional analysis of closely spaced buoys are compared, showing good agreement in significant parameters and in distributions in the frequency range. Differences between wave and wind directions are discussed. A method of separating double peak spectra by fitting theoretical shallow water spectra to the measured energy density distributions is presented.
A NUMERICAL WAVE PREDICTION MODEL FOR PERSONAL COMPUTERS
Authors: Schwab David J.
Published: June 2019

A two-dimensional wave prediction model suitable for use on personal computers is described. The model requires the twodimensional time-dependent wind field as input. Output consists of wave height, wave period, and wave direction estimates at all grid points on a computational grid representing an enclosed or semi-closed basin. Model predictions compare favorably with observations from a wave research tower in Lake Erie. A formula is provided to estimate how long a model simulation would take on a personal computer given the surface area of the computational domain, the grid size, and the computer clock speed.
REDUCTION OF WAVE OVERTOPPING RATE BY THE USE OF ARTIFICIAL REEFS
Authors: Sawaragi Toru , Deguchi Ichiro , Park San-Kil
Published: June 2019

A wave overtopping rate from a sea dike of various toe depths is formulated based on a weir model in an unidirectional flow. To evaluated the wave overtopping rate from a seadike on an artificial reef by the weir model, a numerical procedure for predicting wave transformations including the effect of forced wave breaking on the reef is constructed. After confirming the applicability of the model through experiments with regular and irregular waves, the effect of artificial reef on wave overtopping is discussed. So-called individual wave analysis method is shown to he applicable to the wave overtopping caused by irregular waves.
EFFECT OF BOUSSINESQ EQUATIONS ON WAVE SPECTRA PROPAGATION
Authors: Sierra J.P. , Arcilla A.S. , Egozcue J.J. , Monso J.L.
Published: June 2019

A 2-D numerical model has been developed to simulate wave propagation prior to breaking. This non linear hydrodynamic model works in connection with various spectral analysis routines. This paper intends to study the propagation effects on the wave time-series and on the corresponding spectral density functions in order to gain insight on both the spectral description of waves and irregular wave propagation.
THE INFLUENCE OF CURRENTS ON WAVE ATTENUATION
Authors: Simons Richard R. , Grass Anthony J. , Kyriacou Andreas
Published: June 2019

Measurements have been made of wave height decay in a rough bottomed flume for waves alone and for waves combined with 3 following currents. Tests have also been carried out to quantify energy dissipation at the sidewalls under these conditions. Results show that waves attenuate less rapidly when propagating on a following current, with a corresponding reduction in wave-current friction factor. A simple method is suggested by which wave attenuation in the presence of following and opposing currents can be predicted.
THEORETICAL MODEL FOR NEARSHORE CIRCULATIONS
Authors: Sasaki Mikio , Ozaki Akira , Saeki Hiroshi
Published: June 2019

The dynamics of nearshore circulations is investigated using mass, momentum and energy conservation equations with bottom friction, lateral mixing and wave-current interaction. By means of introducing a perturbation expansion for the mean variables, the first-order solutions are found in the surf and offshore zones according to the boundary conditions at the coast. It is found that:(l) The rip velocity attains a maximum value in the offshore region near the break point as Yr* becomes larger. (2) The longshore velocities become higher in the surf zone and lower in the offshore region with increasing Yr*. (3) The rip and longshore velocities in the surf zone become relatively smaller due to the effects of the bottom friction, and that the rip and longshore velocities in the surf zone become smaller due to the wave-current interaction.
A HYDRODYNAMIC MODEL FOR COMPUTER AIDED HARBOUR ENGINEERING
Authors: Monso J.L. , Arcilla A.S. , Sierra J.P.
Published: June 2019

Coastal hydrodynamic analyses are basic for the planning and assessment of activities in that area. An important application of these-analyses is harbour lay-out and location. In this paper, hydrodynamic results of a numerical model based on Boussinesq-type equations are presented in the issue of Computer Aided Harbour Engineering. This model achleves overall second-order accuracy and has efficient modules of pre- and post-processing of information. The model has been used as a CAD tool for the planning and design of Spanish harbours. Its flexibility and economy of operation allow the model to be used, in the future, as a module of a global expert system for CAD harbour lay-out. This global expert system will provide a fully automatic design process. The output of this system will consist in the final optimized harbour configuration, considering all Imposed constraints and requirements.
SUBGRID MODELLING IN DEPTH INTEGRATED FLOWS
Authors: Madsen P.A. , Rugbjerg M. , Warren I.R.
Published: June 2019

Hydrodynamic simulations in coastal engineering studies are still most commonly carried out using two-dimensional vertically integrated mathematical models. As yet, threedimensional models are too expensive to be put into general use. However, the tendency with 2-D models is to use finer and finer resolution so that it becomes necessary to include approximations to some 3-D phenomena. It has been shown by many authors that simulations of large scale eddies can be quite realistic in 2-D models (c.f. Abbott et al. 1985). Basically there exists two different mechanisms of circulation generation. The first one is based on a balance between horizontally and grid-resolved momentum transfers and the bed resistance - i.e. a balance between the convective momentum terms and the bottom shear stress. The second one is due to momentum transfers that are not resolved at the grid scale but appears instead as horizontally distributed shear stresses. In many practical situations the circulations will be governed by the first mechanism. This is the case if the diameter of the circulation and the grid size is much larger than the water depth. In this situation the eddies are friction dominated so that the effect of sub-grid eddy viscosity is limited. In this case 2-D models are known to produce very realistic results and several comparisons with measurements have been reported in the literature.
ON JOINT DISTRIBUTION OF WAVE HEIGHTS AND DIRECTIONS
Authors: Isobe Masahiko
Published: June 2019

In the individual wave analysis of short-crested irregular waves, the wave direction of an individual wave is an important quantity as well as the wave height and period. In this paper, the joint probability density of the wave height and direction is derived theoretically on the assumption of a narrow-banded frequency spectrum. A field experiment was carried out to examine the validity of the theory. The measured joint distribution agreed well with that predicted by the theory.
FIELD MEASUREMENT OF WAVE SET-UP
Authors: Davis Gregory A. , Nielsen Peter
Published: June 2019

A new, efficient and cheap method is described for obtaining field measurements of surf zone mean water levels. The method applies manometer tubes rather than the traditional pressure transducers. Together with simple stilling well measurements of the water table the results obtained from manometer tubes demonstrate for the first time a complete mean water level profile, from offshore of the break-point to the back-beach region. While some previous studies have provided information about the average position of the waterline, the present study is the first to provide comprehensive field data on the position of the shoreline defined as the intersection of the mean water surface and the sand. The difference between average position of the waterline and the shoreline is not trivial.
ON THE MAXIMUM RUNUP OF CNOIDAL WAVES
Authors: Synolakis Costas Emmanuel , Kumar Manas
Published: June 2019

This is a study of the maximum runup of cnoidal waves on plane beaches. An approximate theory is described for determining the maximum runup of nonbreaking cnoidal waves. It is shown that the linear and nonlinear theory predict mathematically identical maximum runup heights. An asymptotic result is derived for the maximum runup of solitary waves, which are one limiting form of cnoidal waves. A series of laboratory experiments is described to support the theory. Other numerical results are presented that suggest that the runup of cnoidal waves is significantly higher than the runup of monochromatic waves with the same waveheight and wavelength. Preliminary laboratory data are also presented which suggest that, for certain cnoidal waves, the maximum runup is not a monotonically varying function of the normalized wavelength.
A NUMERICAL MODEL OF WAVE DEFORMATION IN SURF ZONE
Authors: Watanabe Akira , Dibajnia Mohammad
Published: June 2019

A numerical model is presented for nearshore wave deformation due to shoaling and breaking, and to decay and recovery in the surf zone. The model is based on a set of time-dependent mild slope equations including a term of wave energy dissipation caused by breaking. Its applicability is demonstrated by comparisons between the computations and the measurements of cross-shore distributions of the wave height and potential energy over typical beach configurations.
COUPLING STOKES AND CNOIDAL WAVE THEORIES IN A NONLINEAR REFRACTION MODEL
Authors: Hardy Thomas A. , Kraus Nicholas C.
Published: June 2019

An efficient numerical model is presented for calculating the refraction and shoaling of finite-amplitude waves over an irregular sea bottom. The model uses third-order Stokes wave theory in relatively deep water and second-order cnoidal wave theory in relatively shallow water. It can also be run using combinations of lower-order wave theories, including a pure linear wave mode. The problem of the connection of Stokes and cnoidal theories is investigated, and it is found that the use of second-order rather than first-order cnoidal theory greatly reduces the connection discontinuity. Calculations are compared with physical model measurements of the height and direction of waves passing over an elliptical shoal. The finite-amplitude wave model gives better qualitative and quantitative agreement with the measurements than the linear model.
SOLITARY WAVES PASSING OVER SUBMERGED BREAKWATERS
Authors: Cooker Mark , Peregrine Howell
Published: June 2019

A method is described for the computation of the two-dimensional unsteady motion of a solitary wave passing over submerged breakwaters. Far from the breakwater the fluid is assumed static and the sea bed is level. The fluid motion is assumed to be irrotational, incompressible and inviscid. The exact boundary conditions at the free surface and the impermeable bed are satisfied. Laplace's equation for the velocity potential is solved using a boundary integral method. Numerical results are reported which show the variety of ways in which solitary waves are distorted when they encounter submerged breakwaters.
WAVE RUN-UP PREDICTION VS. MODEL TEST RESULTS: A COMPARISON
Authors: Gadd Peter E. , Manikian Victor , Machemehl Jerry L.
Published: June 2019

Large-scale physical model test measurements of wave run-up are compared with wave run-up prediction derived from the Shore Protection Manual (SPM). Noteworthy discrepancies between the results of these two methods have been identified that include substantial overestimation of wave run-up elevations using the SPM approach, and computation of roughness coefficient values that vary as a function of wave steepness. The slope armors tested in the study at model scales of 1:3 and 1:4 include linked concrete matting and overlapped gravel-filled fabric bags.
STATISTICAL PROPERTIES OF THE MAXIMUM RUN OF IRREGULAR SEA WAVES
Authors: Kimura Akira
Published: June 2019

The probability distribution of the maximum run of irregular wave height is introduced theoretically. Probability distributions for the 2nd maximum, 3rd maximum and further maximum runs are also introduced. Their statistical properties, including the means and their confidence regions, are applied to the verification of experiments with irregular waves in the realization of a "severe sea state" in the test.
SOME RESULTS FROM THE LABRADOR SEA EXTREME WAVES EXPERIMENT
Authors: Kjeldsen Soren Peter , Krogstad Harald Elias , Olsen Richard Bjarne
Published: June 2019

The Labrador Sea Extreme Waves Experiment (LEWEX), is an international basic research programme concerned with full-scale measurements, analysis, modelling and simulation in test basins of 3-dimensional seas. The research is carried out in order to assess the significance of 3-dimensional sea states in engineering applications. The first phase of the programme full scale wave measurements in the North Atlantic Ocean was performed at a site and time that had a high probability of encountering severe sea states. The present publication shows examples of measured bi-modal directional sea spectra obtained with the WAVESCAN buoy and directional sea spectra measured with an airborne Synthetic Aperture Radar (SAR). Directional spectra of gravity waves are obtained with the SAR both in open waters and below an ice cover. Further work is needed in order to verify SAR-measurements with in-situ observations. In-situ measured directional spectra are also compared with hindcast spectra from the 3G-WAM model. Hindcast significant wave heights were found to be lower than the in-situ measurements.
ON THE PARTITION OF HORIZONTAL MOMENTUM BETWEEN VELOCITY AND PRESSURE COMPONENTS THROUGH THE TRANSITION REGION OF BREAKING WAVES
Authors: Basco David R. , Yamashita Takao
Published: June 2019

When a water wave breaks, it undergoes a complicated interchange of total, depth integrated horizontal momentum between that part due to the velocity field and the part that can be assigned to the pressure distribution beneath the surface. This partition of total momentum for a strong, plunging breaker is described by a relatively crude model in which the horizontal velocity profile (over the vertical) is schematized in two layers and the pressure distribution is related to a hydrostatic distribution for the given water depth. An example calculation at four locations across the breaking transition region on a plane beach is utilized to demonstrate the principles of the model. The limitations of the approach which assumes momentum conservation in a reference frame moving with the wave celerity defined at the wave crest are presented, but await verification. The ultimate goal is a relatively simple model to predict the transition width of breaking waves (spillers, plungers and intermediate types) for plain and bar-trough beaches.
A DIRECTIONAL PREDICTION MODEL OF WAVES WITH VARIABLE WIND
Authors: Acinas Juan R.
Published: June 2019

A model of the response of the direction of the waves to changing winds is presented. First the theoretical results that associate an average direction of energy propagation to every wave component is introduced. From this model, numerical results are presented both by simulations of ideal wind veering situations and compared with field data taken from pitch and roll buoys.
GRAIN-GRAIN INTERACTION IN OSCILLATING SHEETFLOW
Authors: Bakker W.T. , Van Kesteren W.G.M. , Yu Z.H.
Published: June 2019

Viscous grain-grain interaction is an important aspect of the dynamics of oscillating sheetflow. This interaction between sand grains has been investigated qualitatively in a pulsating water tunnel. Furthermore, experiments concerning the interaction between neutrally buoyant spheres in a Couette flow have been carried out at a scale of 100:1 in a new developed ring shear apparatus, called " Carrousel." With respect to the dynamics of sheetflow, in-situ measuring devices for the sand concentration in the sheetflow ("Harp") and the bed load ("Swan") has been developed; some preliminary results are shown. For sand grains, the intrusion depth of sheetflow appears to be of the order of several mm. On high speed video recordings no lateral mixing between grain layers can be observed; for this some physical explanation is given. This supports the modelling of the sheetflow mechanism as moving grain layers.
OSCILLATORY BOTTOM BOUNDARY LAYER BY LOW-REYNOLDS NUMBER TURBULENCE MODEL
Authors: Asano Toshiyuki , Goda Hitomi , Iwagaki Yuichi
Published: June 2019

Characteristics of mean velocity and turbulence properties in oscillatory bottom boundary layers are investigated with low- Reynolds number turbulence model. Since this model is capable to describe the flow field close to the bottom, special attentions are paid on the characteristics of the viscous sublayer. Several interesting results, which coincide with or differ from existing knowledge on steady bottom boundary layers, are presented in paticular on the mean velocity profile, turbulent viscosity coefficient and growth of the viscous sublayer.
SEAWALL OVERTOPPING MODEL
Authors: Ahrens John P. , Heimbaugh Martha S.
Published: June 2019

Results from an extensive series of laboratory tests of irregular wave overtopping for a number of seawall and seawall/revetment configurations is presented. Data for 13 configurations has been collected and grouped into 7 data sets representing relatively similar geometrical characteristics. All data sets showed an approximately exponential relationship between the overtopping rate and a dimensionless freeboard parameter which is the ratio of the seawall freeboard to the local wave severity. This finding logically led to the development of three progressively more complex overtopping models. The models provide a relatively simple way to estimate overtopping rates and an objective way to evaluate the hydraulic performance of seawalls/revetments. Advantages and disadvantages of the models are discussed and their ability to predict overtopping rates is compared.
CLOSED-FORM SOLUTIONS FOR THE PROBABILITY DENSITY OF WAVE HEIGHT IN THE SURF ZONE
Authors: Dally William R. , Dean Robert G.
Published: June 2019

By invoking the assumption that in the surf zone, random waves behave as a collection of individual regular waves, two closed-form solutions for the probability density function of wave height on planar beaches are derived. The first uses shallow water linear theory for wave shoaling, assumes a uniform incipient condition, and prescribes breaking with a regular wave model that includes both bottom slope and wave steepness effects on the rate of decay. In the second model, the shallow water assumption is removed, and a distribution in wave period (incipient condition) is included. Preliminary results indicate that the models exhibit much of the behavior noted for random wave transformation reported in the literature, including bottom slope and wave steepness effects on the shape of the probability density function.
DESIGN WAVES AND THEIR PROBABILITY DENSITY FUNCTIONS
Authors: Rossouw J.
Published: June 2019

Design wave heights were estimated from measured data using a virtually continuous data set consisting of 8 years of waverider data. Evidence is given which shows that waveriders tend to malfunction during storms. Special care was taken to select independant and identically distributed samples from the data before fitting a number of probability distributions to the selected wave heights. Bootstrap techniques were used to select the models that give the best fit to the data as well as to determine the confidence bands for the predicted design wave heights. It is shown that once the model for the long term distribution of wave height is chosen, relatively narrow confidence bands can be obtained for the most probable value of up to the 100 year return period wave if maximum use is made of the available data. Uncertainty about the selection of the model and the representativeness of the measurements however reduces the usefulness of these confidence bands. A plea is also made in the paper to stop using the concept of a wave with a certain recurrence interval but rather to specify a wave with a given risk of being exceeded within the design life of the structure.
A BAROTROPIC 3D-MODEL FOR THE STUDY OF CURRENTS AROUND THE ATLANTIC COAST OF THE IBERIAN PENINSULA
Authors: Rodriguez I. , Krohn J. , Backhaus J.O.
Published: June 2019

We intend to present a brief description of the fundamen tals of a barotropic version of the 3D numerical model of the Institut fiir Meereskunde-Hamburg altogether with some results concerning the application of the model to the simulation of tidal currents in the Spanish atlantlc waters.
KINEMATICS OF BREAKING WAVES IN COASTAL REGIONS
Authors: Easson William J. , Griffiths Matthew W.P. , Greated Clive A.
Published: June 2019

Waves breaking on various slopes in a wave flume are examined. Plunging and spilling breakers are considered. The parametric results show the consistency of the measurement and the independence of scale. A method is given for predicting the maximum breaking height for a wave of known period in a known depth. The velocity is measured to the crest of the wave and comparisions with numerical and analytical solutions demonstrate the shortcomings of many of the established methods of predicting wave kinematics.
UNSTEADY FLOW AROUND A VERTICAL CIRCULAR CYLINDER IN A WAVE
Authors: Hayashi Kenjirou , Shigemura Toshiyuki
Published: June 2019

The unsteady characteristics of flow around a vertical circular cylinder in a typical wave, under which the lift force acting on it is very stable and has a frequency which is twice that of the incident wave, have been investigated experimentally. The relationship between the fluctuating flow velocities near the boundary layer separation points and the lift force acting on a sectional part of the cylinder has been understood quantitatively. To clarify the region where the appearance of stable lift force occurs, the long time records of lift forces acting on vertical cylinders in waves are also performed.
A STEADY-STATE WAVE MODEL FOR COASTAL APPLICATIONS
Authors: Resio Donald T.
Published: June 2019

A steady-state spectral model is presented. This model produces a solution equivalent to a full time-stepping spectral model, but at much reduced computational times. Comparisons shown here demonstrate that the spectral model provides a good representation of shallow-water wave propagation phenomena and that wind effects can significantly influence near-coast wave conditions.