bluuebunny/crossref_metadata_2025 huggingface dataset:
AN APPROACH TO AN OFF-SHORE WAVE CLIMATOLOGY
Authors: McCulloch J.A.W.
Published: June 2019

A project to derive a wave climatology for that portion of the Atlantic Ocean between 30° and 60° N. and west of 30° W, recently begun by the Atmospheric Environment Service of Environment Canada, is described. The data base is produced from isolines of significant wave height and from plotted ship data. Details of the preparation of the basic analysis as well as the design of the remainder of the project are presented. Intermediate results will provide guidance to potential users of the wave climatology until sufficient data have been accumulated to lend statistical reliability to the analysis.
SUSPENDED SEDIMENT AND LONGSHORE SEDIMENT TRANSPORT DATA REVIEW
Authors: Das M.M.
Published: June 2019

A review of laboratory and field studies on suspended sediment under waves shows that although about five analytical or semi-empirical approaches have been attempted to predict the vertical distribution of suspended sediment, none of the approaches has had its general validity proven. This is mainly due to the lack of knowledge about the characteristics of turbulence of the wave boundary layer and to the lack of a suitable suspended sediment measuring technique for use in waves. Six different suspended sediment measuring techniques have been used in the studies previewed. Although none of them gives completely reliable laboratory or field measurements, an optical system appears to show promise in obtaining information on the mechanics of suspension under waves. The reanalysis of longshore sediment transport data and tests of the relationships Q = A..E , Q = A,,E , and I = A,,E , where Q is volume transport rate in cubic yards per day, E is longshore component of wave energy flux in lbs per day per foot of beach and I is immersed weight transport rate in lbs per day, for different subsets of data and using the method of least squares, showed that a single set of A-, A,, and B does not fit all subsets of data with minimum average percentage deviation of observed values from those predictable by the relationships. The subset of data consisting of all but the observations with light weight sediments can be described by the line of fit, Q =1.93 X 10-4E , with the observed data differing from the predicted ones by 74 percent on the average.
INSTRUMENT FOR LONG-TERM MEASUREMENT OF SUSPENDED MATTER (SILT GAUGE)
Authors: Gohren Harald , Laucht Hans
Published: June 2019

With financial support by the German Research Association (Deutsche Forschungsgemeinschaft) an instrument for automatic long-term measurement of suspended matter has been developed by the authors. It works on a settling method. A sample of 20 1 of water is pumped into a conical settling bottle every hour. The suspended sediments settling in a measuring tube at the bottom of the bottle are recorded by a camera. The device called "Silt Gauge" is intended for long-term measurements in shallow coastal water.
EXPERIMENTS ON BED FORM GENERATION BY WAVE ACTION
Authors: Mogridge G.R. , Kamphuis J.W.
Published: June 2019

Experiments to determine the length, height and steepness of bed forms generated by wave action have been conducted in a laboratory wave flume and an oscillating water tunnel. The effects of a wide range of oscillatory flows were examined on polystyrene (specific gravity 1.05, diameter 1.54 mms), bakelite (specific gravity 1.60, diameter 0.52 mms), bakelite (specific gravity 1.51, diameter 0.67 mms) and sand (specific gravity 2.68, diameter 0.36 mms). From the results of the experiments design curves were plotted which make it possible to predict the length and height of bed form that will develop on any specified sediment bed for given conditions of fluid oscillation.
SCALE SELECTION FOR MOBILE BED WAVE MODELS
Authors: Kamphuis J. William
Published: June 2019

A rational basis for the design of wave models with a mobile bed is presented. The discussion is of a preliminary nature and further model analysis, underway at present at Queen's University, should introduce a sounder basis for model design.
MOVABLE-BED MODEL STUDIES OF PERCHED BEACH CONCEPT
Authors: Chatham C.B.
Published: June 2019

Hydraulic model studies were conducted to aid in ascertaining the technical feasibility and optimum design factors of the perched beach concept. Among these were two-dimensional, movable-bed studies to determine an estimate of the amount of sand which would be lost seaward over the submerged toe structure by normal and storm wave action, the optimum elevation of the submerged toe structure, and the length of a stone blanket required to reduce seaward migration of sand to a minimum. The model beach was subjected to test waves until equilibrium was reached for a wide range of wave conditions for both the existing beach and the perched beach. Test results indicate that (a) little or no beachfill material will be lost seaward of the toe structure for normal wave conditions but the larger storm waves may cause erosion of the perched beach, (b) the installation of a stone blanket shoreward of the toe structure will reduce the amount of beach erosion, (c) if the beach fill is extended a sufficient distance seaward, the toe structure serves no useful purpose, and (d) a three-dimensional movable-bed model study is feasible and is necessary to determine the final design features of a perched beach.
EQUILIBRIUM CONDITIONS IN BEACH WAVE INTERACTION
Authors: Raman H.
Published: June 2019

Laboratory studies were conducted in an attempt to find out a relationship between beach and wave characteristics when equilibrium conditions are reached in beach wave interaction for the simple case of regular waves acting normal to the beach. Experimental results indicate the existence of stable points on beach profiles where the coordinates of the profile do not change with time when waves of constant characteristics act on the beach. Emperical relationship between the wave and beach properties are proposed. A new criterion for classification of beach profiles is indicated.
HAWAIIAN BEACHES
Authors: Gerritsen Frans
Published: June 2019

Hawaii's beaches are of great economical and. social value; they serve a variety of purposes and are valuable both to residents and tourists alike. Like in many other parts of the world, many of Hawaii's beaches are in a state of erosion and measures of improvement must be designed to cope with this problem. Although in the past several studies have been undertaken to evaluate Hawaii's beach systems and to analyze possible measures of improvement, this study aims at an in-depth analysis of the physical factors at work in the coastal zone. A thorough understanding of these processes, it is felt, is indispensable for the application of sound and economic measures in stabilizing and maintaining Hawaii's beaches. This paper describes some preliminary results of field studies conducted in Waikiki Beach. The latter beach was chosen because of the pressing need for improvements and because of its convenient location. In order to project this study against the proper background, a short review of the general characteristics of Hawaiian beaches precedes the results of the Waikiki Beach study.
DUNE EROSION DURING STORM CONDITIONS
Authors: Edelman T.
Published: June 2019

Starting from a provisional hypothesis, presented by the author at the 11 Conference on Coastal Engineering, this paper deals with the further development of our knowledge about dune erosion during storm conditions. Results of measurements in the prototype are mentioned. Some speculations about the occuring processes during storms are given. However, the problem has not yet been solved. Further measurements in the prototype will be necessary.
ARTIFICIAL BEACH NOURISHMENT ON THE GERMAN NORTH SEA COAST
Authors: Kramer Johann
Published: June 2019

Several artificial beach nourishments were completed during the last twenty years on the German North Sea coast. Investigations made it possible to settle different problems connected with artificial beach nourishment and to gain additional information and experience. At present beach nourishments at Langeoog and Sylt will be realized in a way which is expected to bring the highest effectiveness. The hydrodynamic processes in connection with these beach nourishments and their change in shape will be subject to the paper.
COASTAL SAND MINING IN NORTHERN CALIFORNIA, U.S.A.
Authors: Magoon Orville T. , Haugen John C. , Sloan Robert L.
Published: June 2019

The commercial mining of sand at coastal locations along California has been a continuing activity at some sites, sporadic at others and altogether discontinued at still other sites. This mining activity includes all methods of sand mining (dragline, self-propelled bottom-dump scrapers, diesel shovels, etc.) and may be classified by littoral zone location as (1) mining from a beach foreshore or backshore area wetted by the normal tidal range, (2) mining within a river mouth or other estuary upstream from the ocean but still within the tidal zone, and (3) mining from bluff or dune areas not wetted by the normal range of tides but still within the littoral system. Processing of the sand thus mined takes place when the material is transported from the mining site, usually by end dump trucks or belt conveyor to either a fixed or a portable plant. Commercial uses of the sand thus mined fall into two general categories, (1) construction and (2) special purposes. Construction usage includes aggregate for concrete, asphalt, mortar, plaster and stucco, base material in road construction, and fill and structural backfill. Specialty uses include sand blasting and filtration material, foundry and engine sands, and raw material for manufacture of glass and ceramics. Within the area studied (see Figure 1) the Monterey Bay area has the highest concentration of mining activity. To the north, the area around Fort Bragg yields significant quantities to the commercial miner. Most of the remaining coastal sand mining activity is concentrated in the San Francisco area.
STANDING WAVES IN FRONT OF A SLOPING DIKE
Authors: Shuto Nobuo
Published: June 2019

A solution of two-dimensional long waves on a beach of uniform slope is connected with that in water of constant depth, in order to yield an approximate solution for standing waves in front of a sloping dike. Wave motions are expressed in the Lagrangian description. The highest possible standing waves as well as the reflection coefficient are calculated according to the Miche's conception. Theoretical results show a good agreement with the experimental results of Murota and Yamada. It is also predicted that there is a relationship between the wave overtopping quantity and the quantity of water of standing waves above the crest height of the dike. As for the wave pressure of standing waves, a simple formula in the Eulerian description is derived for relative-dike length -t/L < 0.16 by allowing 670 error.
PRESSURE UPON VERTICAL WALLS FROM OVERTOPPING WAVES
Authors: Plakida M.E.
Published: June 2019

This paper is concerned with the study of wave pressures exerted upon breakwaters of the vertical type from overtopping waves- The formulae for maximum wave pressure upon vertical walls and the wave crest elevation for overtopping waves are suggested by the author. The phase interval method for the maximum wave pressure is also given.
A PRELIMINARY STUDY OF STORM SURGES IN HUDSON BAY
Authors: Yuen K.B. , Murty T.S.
Published: June 2019

In view of resource exploration, hydro-electric power development and other activities, there is a clear need for a better understanding of the hydrodynamics of Hudson Bay. One particular area that has received little attention in the past is storm surges. It is likely that a storm surge prediction will be very useful in the future and towards this goal a two-dimensional homogenous model has been constructed. A hindcast of the storm of October 15, 1969 is presented here. The calculated surge for Churchill, Manitoba compares favourably with observed residues. The overall response of the basin and the types of oscillations that are produced are also described here. In addition, the differences in behavior between James Bay and Hudson Bay proper are demonstrated. Finally the results also indicate the steady circulation which the storm has produced.
A PROBABILISTIC APPROACH TO DETERMINE WAVE FORCES ON OCEAN PILE STRUCTURES
Authors: Schueller G.I. , Shah H.C.
Published: June 2019

Multiple linear regression analysis is applied to predict horizontal velocities and acceleration of water particles subjected to waves. Furthermore it was used to predict the coefficient of drag for circular piles. The mean value functions of the parameters are calculated and the assumption of their lognormal distribution reasonably well verified. The method used here is free from theoretical assumptions about wave mechanisms and, hence, explains the behavior of experimental results. Using Monte Carlo simulation these regression relations were then utilized to generate the distribution functions of wave forces. Using the Morison force equation, in this simulation, the distribution function for the drag and the inertial components of the force are determined separately. A linear superposition of those time varying processes was performed to obtain the distribution of the total maximum force. Finally a probabilistic wave height-wave force relationship was developed for the purpose of creating a force distribution function given a random sea state.
WAVE FORCES ON SUBMERGED PIPE LINES
Authors: Brater Ernest F. , Wallace Roger
Published: June 2019

This is a presentation of the analyses of data obtained from a laboratory investigation of horizontal forces produced by oscillatory waves on submerged pipes. The research program was planned to help solve design problems for pipe lines located on or below the bottom in the oceans or the Great Lakes. The project was financed by the National Science Foundation. A continuous record of wave height and horizontal force was obtained for pipes of four diameters, for three wave heights and three wave lengths. Forces were measured at four locations below the water surface, the lowest position being as near the bottom as possible. Other tests were conducted with the pipes located in various positions within trenches of several different shapes. The actual pipe diameters, wave heights and wave periods used in the laboratory tests were such that on the basis of a scale ratio of 1 to 75 the range of prototype parameters would include pipe diameters varying from 8 to 15 feet, wave heights varying from 8 to 23 feet and wave periods in the range from 6 seconds to 12 seconds. Results are presented in the form of coefficients of inertial resistance and drag which can be used with the Airy equations to compute forces.
EXTREME LEVELS ARISING FROM METEOROLOGICAL SURGES
Authors: Ackers P. , Ruxton T.D.
Published: June 2019

The design of coastal works depends on estimating the probabilities of extreme water levels, as well as of waves Previous studies of surge-affected levels have extrapolated observed annual maxima or the n highest levels in n years to predict rarer events In addition to using these well-established methods, m this study of tide levels on the Essex coast of Britain a long term record of extreme levels was synthesised by adding surge residuals at the time of predicted HW to predicted HW levels, treating them as statistically independent events Many more large surge residuals have been measured than extreme water levels as many surges are associated with small tides Events with return periods up to 1000 years may be estimated without extrapolating beyond the range of observed surge residuals and predicted tides This method is assessed in relation to previous methods and information relevant to the design of coastal works in the south western part of the North Sea was obtained In addition to forecasting the probabilities of high tide levels, the study included wave forecasts and the encounter probabilities of combinations of sea level and wave height for various aspects of coastal developments.
A LOW-COST INSHORE WAVE DIRECTION INDICATOR
Authors: Retief G. de F. , Vonk A.P.M.
Published: June 2019

Although many attempts have been made in the past to measure the direction of propagation of ocean waves, a need for a simple, reliable solution to the problem has remained. The technique described here, intended for near-shore usage, makes use of a simple bottom-mounted flow direction indicator. The influence of rip and longshore currents on wave direction recordings is identified and a means of reducing these steady state current effects by a reduction in gauge sensitivity is presented, along with various possible recording and analysis techniques. Usefulness of the gauge is established as a simple engineering tool with certain limitations and examples are given of »'aire direction recordings related to meteorological data. A possible usage of the gauge FE an approximate sediment transport indicator is also proposed.
BREAKING WAVE FORCES ON A LARGE DIAMETER CELL
Authors: Watanbe Akira , Horikawa Kiyoshi
Published: June 2019

Experiments have been carried out by using non-breaking waves and breaking waves to investigate the wave forces on a vertical circular cell located in the shallow water. Based on the experimental data, the drag coefficient and the inertia coefficient of a circular cylinder and the curling factor of breaking waves are estimated, and the computation methods of wave forces are examined. As a result, it is shown that the phase lag of inertia forces behind the accelerations of water particles should be considered for the estimation of the drag coefficient as well as the inertia coefficient. In addition the previous formula of the maximum breaking wave forces acting on a cell or a pile is revised by introducing the effects of the above-mentioned phase lag and another phase difference, both of which are functions of the ratio of the cell diameter to the wave length. - It is confirmed that the proposed formula is applicable even to the large cell with the diameter comparable to the wave length.
IMPACT PRESSURES PRODUCED BY BREAKING WAVES
Authors: Ackerman Norbert L. , Chen Ping-Ho
Published: June 2019

Experiments were conducted in a vacuum tank in order to investigate the effect which entrained air has on impact loads which are produced when waves break upon a structure. In these experiments a flat plate was dropped onto a still water surface in an environment where the ambient pressure of the surrounding air could be controlled. Rings of varying height were fixed to the surface of the falling plate in order to trap different volumes of air between the falling plate and the water, Experimentally determined values were obtained of the maximum pressure pmax when the plate struck the water surface for various ring heights 6 and ambient pressures p0 in the vacuum tank. Experimental results indicate that the pressure rise or shock pressure Ps ~ (Pmax~Po) decreased with reductions in the ambient pressure and volume of entrapped air. Even when air was removed such that the absolute pressure in the tank was equal to the vapor pressure of the water, water hammer conditions, where the peak pressures depend upon the celerity of sound waves in the media, were never found to occur.
TOTAL WAVE FORCE ON A VERTICAL CIRCULAR CYLINDRICAL PILE
Authors: Tsuchiya Yoshito , Yamaguchi Masataka
Published: June 2019

This paper deals with the estimation of total wave force on a vertical circular cylindrical pile. Firstly, finite amplitude wave theories such as those of Stokes waves and cnoidal waves are recalculated by the Stokes second definition of wave celerity and the applicability of the theories for wave crest height above the still water level, wave celerity and horizontal water particle velocity is briefly discussed. Secondly, the drag and inertia coefficients are estimated respectively from the results of experiments for total wave force by the authors and by other researchers, based on the Morison wave force equation applying the theories and characteristics of the coefficients are considered in relation to the wave characteristics and pile dimension. Lastly, the applicability of the wave force equation proposed is investigated in comparison with experimental and theoretical results for time variation of total wave force and maximum total wave force.
FORCES FROM FLUID FLOW AROUND OBJECTS
Authors: Nath John H. , Yamamoto Tokuo
Published: June 2019

All hydrodynamic forces on submerged objects are shown to be due to the acceleration effects of the fluid flow. However, it is useful to consider separately the influence from the various ambient flow and local flow conditions. At times certain aspects of the flow can be ignored, which simplifies the analysis. Examples are developed for circular cylinders near a plane boundary with a flow direction parallel to the boundary and perpendicular to the cylinder. Potential flow theory predicts that large vertical forces exist away from the boundary when the cylinder is against the boundary and that large negative forces exist toward the boundary when the cylinder is positioned a small distance from the boundary, when the viscous effects are small. When the cylinder is near the boundary, the added mass coefficient is the same regardless of the direction of the flow, providing the flow is perpendicular to the cylinder. In addition, the added mass coefficient is much larger for cylinders near the boundary than when they are in a free stream. Good agreement between theory and laboratory experimentation was obtained for various coefficients with waves on horizontal cylinders near a plane boundary.
LAMINAR BOUNDARY LAYER AROUND A CIRCULAR CYLINDER UNDER OSCILLATORY WAVES
Authors: Iwagaki Yuichi , Ishida Hajime
Published: June 2019

A solution of water particle velocities in the boundary layer developed by monochromatic waves on the surface of a circular cylinder is obtained by applying the boundary layer approximations and perturbation method to the Navier-Stokes and continuity equations represented in the cylindrical coordinates. Since, in this process, it is necessary to give the velocity outside the boundary layer, the water particle velocities of diffracted waves around the cylinder are derived from MacCamy-Fuchs' velocity potential. Moreover, the occurrence of laminar flow separation is explained by using this solution. On the other hand, using a hydrogen bubble tracer some experiments have been performed about the water particle velocities of diffracted waves, velocity profiles in the boundary layer and occurrence of wake vortices. These results are compared with theoretical ones.
WAVE SCATTERING BY PERMEABLE AND IMPERMEABLE BREAKWATER OF ARBITRARY SHAPE
Authors: Ijima Takeshi , Chou Chung Ren , Yumura Yasu
Published: June 2019

This paper deals with a theoretical method of calculation of the fluid motion, when a sinusoidal plane wave incidents to a permeable breakwater of arbitrary shape at constant water depth and shows that the problem for impermeable breakwater is solved as a special case of this method. The method described here is the extension of the author's method of solution for two-dimensional permeable breakwater by the method of continuation of velocity potentials for two different fluid regions into three-dimensional problems by means of Green functions. Here, the analytical process of calculation is presented and as representative examples, wave height distributions and wave forces around an isolated elliptic- and rectangular breakwater are calculated and compared with experiments in wave channel. The principle of this method is also applied to the analysis of submerged and semi-immersed fixed cylinder and the motions of floating body of arbitrary.
RUN-UP DUE TO BREAKING AND NON-BREAKING WAVES
Authors: Raichlen F. , Hammack J.L.
Published: June 2019

This study was conducted to Investigate the effect of incident wave parameters on run-up for both a smooth-faced structure and a structure armored with quarry-stone. The ratio of the depth-to-wave length (the relative depth) was found to be important in defining wave run-up for both cases. The relative run-up (expressed as the ratio of the run-up elevation above still water level to the incident wave height) for waves which break at the toe of the structure was less than the maximum relative run-up for non-breaking waves for the same relative depth. For both structures, the maximum relative run-up for experiments with long waves occurred at a value of the modified Ursell number, (1/2IT) (HL2/h3) , of order unity which indicates that the nonlinear and linear effects are approximately equal in the incident wave.
ESTIMATION OP WAVE OVERTOPPING QUANTITY OVER SEA-WALLS
Authors: Takada Akira
Published: June 2019

This paper tried to formulate the wave overtopping quantity by using a model of overtopping mechanism. Namely, the author investigated the problem by applying the "Calculation method for discharge of overflow weirs" i.e. the method of Fukui et al.'(1963) and Shi-igai et al. (1970)2).
ECONOMIC APPROACH TO OPTIMIZING DESIGN PARAMETERS
Authors: Watt W. Edgar , Wilson Kenneth C.
Published: June 2019

For coastal engineering works, as for other structures, the designer must search for the economic optimum point. This point represents the minimum in the sum of direct cost and cost of possible future damage. By setting up functional representations of these costs the optimum can be obtained directly. This approach is illustrated by models developed independently in the Netherlands and in Canada. At this stage the output of the models may be denoted as the 'perfect knowledge' optimum, in the sense that parameters of the cost functions are assumed to be known with complete accuracy. In the 'real world' case, however, the estimated values of the parameters will be subject to considerable uncertainty. It is shown that because of this uncertainty the 'real world' design optimum will generally be shifted to give a structure larger than that indicated by the 'perfect knowledge' assumption. The novel contribution of the present paper consists of analyzing this shift to obtain simple expressions for the apparent overdesign due to uncertainty and for the resulting cost increase. An illustrative example is presented.
ANCIENT AND MODERN HARBORS: A REPEATING PHYLOGENY
Authors: Inman Douglas L.
Published: June 2019

The Minoans and Phoenicians appear to have developed a very superior "lay" understanding of waves and currents, which led to the development of remarkable concepts in working with natural forces in their coastal engineering works. For example, the Phoenicians developed a "continuous self-flushing" harbor at Tyre and possibly a "flushable" harbor for the removal of sand and silt at Sidon. It would appear that developments of this type were the outgrowth of the close association with and acute observation of nature that occurs where a coastal people learn to work with currents and sail, in the absence of technology for harnessing large amounts of power. However, harbor design became markedly stereotyped following the development of large engineering corps with the capacity for rapid and massive construction. The earlier innovative, natural concepts in harbor design appear to have become obscured by the end of the Roman era, and have remained relatively unused to this day. In view of man's present extensive intervention in the coastal zone, mostly based on "brute force" technology, a careful study of the ancients' ability to work with nature provides valuable insight for today's problems.
BASIC SYSTEMS OF WIND WAVE FIELD
Authors: Krylov Yu. M. , Strekalov S.S. , Tsyloukhin V. Ph.
Published: June 2019

The study of wind waves is usually carried out in the following manner. At the first moment a homogenous wind field with the constant speed directed from the shore to the basin is occurred over the water surface restricted by a straight shore line. It is required to calculate statistic wave characteristics as functions of time and distance from the shore. When solving the problem in such a way the explorers [.1-6 ~] usually came to a conclusion of the system development of gravitational waves with a main energy maximum the amplitude and period of which rise in process developing from small magnitudes to limiting values. Some explorers noted that the two -or three-wave systems under the conditions of constant wind are available. The first results of this theory were obtained by L.Ph. Tytov. In studies of stereophotographs of sea waves he noted and described quantitatively two types of waves: "prevailing" and "large", f7l I* is possible to show that the first type of waves has a phase speed that is less than wind speed, and the second one is equal to wind speed. At a later time G.Neumann [6J generalizing results of ocean observations has come to the conclusion that under the action of constant wind three "specific" wave systems which have phase speeds less, equal and 1.2 more than the speed of wind are developed. However, Tytov's and Neumann's results didn't receive a progress, and later on they were substituted by the conception of continuous wave spectrum with one energy maximum £3-6J - Nevertheless, the opinions of availability of two-or three-wave systems as a typical feature of wind rough sea [8,9] were published in the press.
ESTIMATION OF BOUNDARY CONDITIONS FOR COASTAL MODELS
Authors: Liu S.K. , Leendertse J.J. , Voogt J.
Published: June 2019

In this study, frequency response and transfer function techniques are used together with cross-spectral and fast Fourier transform methods to determine the proper boundary values for computing the flow field of a coastal sea. Tide data containing considerable perturbations from swell and meteorological disturbances are analyzed. In computing the frequency response estimates, the effect of noise in the input is treated by a cancelling technique and by the choice of a reference station to evaluate the interdependencies among the other stations at the boundary. The usefulness of the network frequency response function is threefold: (1) future conditions can be simulated using observed water levels at any single location, (2) boundary information for models of different grid size can be obtained by interpolation, and (3) missing data at a given location can be estimated optimally using data at neighboring stations and the network response function. The paper discusses an example of such an application, the determination of a boundary of a two-dimensional model of Jamaica Bay, New York City, U.S.A.
BUOYANT DISCHARGES FROM SUBMERGED MULTIPORT DIFFUSERS
Authors: Harleman Donald R.F. , Jirka Gerhard H.
Published: June 2019

The application of submerged multiport diffusers for the discharge of degradable liquid wastes and of heated cooling water from electric power generation forms an important aspect of coastal zone management. Previous buoyant jet models for submerged diffuser discharge have been developed for the limiting case of discharge in unconfined deep water in the form of rising buoyant jets. These models can be used for sewage diffusers, but are not applicable for diffusers in shallow receiving water with low buoyancy, the type used for thermal discharges ("thermal diffusers"). A multiport diffuser will produce a general three-dimensional flow. Yet the predominantly two dimensional flow which exists in the center portion of the three-dimensional diffuser can be analyzed as a two-dimensional "channel model". Theoretical solutions for diffuser-induced dilutions are derived for the two-dimensional case and verified experimentally. Furthermore, the theory can be applied to the three-dimensional situation by requiring equivalency of far-field effects, that is the frictional resistance governing the diffuser-induced motion at larger distances from the diffuser line.
TIDE-INDUCED MASS TRANSPORT IN LAGOON-INLET SYSTEMS
Authors: Van de Kreeke J. , Cotter D.C.
Published: June 2019

This paper examines the tide-induced net discharge in lagoon-inlet systems. In particular, attention is given to the role inlets play in inducing a steady current. The flow in the lagoon is described by the one-dimensional long wave equations, the flow in the inlets is described by a semi-empirical equation. Both numerical and analytical techniques are employed to solve for the net discharge. The results of the study indicate that 1) the net discharge can be significant provided the tidal amplitude to depth ratio is not small 2) the net discharge can be considerably increased by the proper selection of the inlet dimensions.
THREE DESIGN SYSTEMS FOR APPLICATIONS IB COASTAL ENGINEERING
Authors: Abbott M.B. , Bertelsen J. Aa. , Verwey A.
Published: June 2019

The Computational Hydraulics Centre in Copenhagen has developed three design systems for applications in hydraulics, coastal and offshore engineering. Each system constitutes a software - documentation entity that automatically constructs and runs mathematical models of a specific class when presented only with the model description. The systems concerned are as follows: System 11, "Siva", is restricted to 1-dimensional flows of 1-layer (vertically homogeneous) fluids. System 21, "Jupiter", applies to 2-dimensional flows of 1-layer fluids. Systems 12/13 and 22/23, "Neptune", apply to 1-dimensional flows with 2 or 3 layers for the 12/13 and 2-dimensional flows with 2 or 3 layers for the 22/23. Brief descriptions of these systems follow.
HORIZONTAL DIFFUSION IN A TIDAL MODEL
Authors: Higuchi Haruo , Yanagi Tetsuo
Published: June 2019

The effect of the tidal residual flow on the horizontal diffusion in a shallow tidal bay is investigated through a hydraulic model experiment, for which Mikawa Bay in central Japan was used as a prototype. A hydraulic model of about 20 x 30 m including Mikawa Bay and neighboring sea area, with a horizontal and vertical scale of 1/2000 and 1/160 respectively, was used, and a semi-diurnal tide was provided for it. Experiments nave shown that tide and tidal current are well reproduced in the model. The tidal locus does not close, that means the existence of the residual flow. The distribution of the concentration of the dye, which is discharged from the bay bottom, corresponds to the pattern of the residual flow. The diffusion coefficient in the bay obtained through one dimensional analysis is the order of 10' cm2/sec and that through two dimensional analysis is less by one order and the dispersion coefficient becomes 105 cm2/sec. It is concluded that the dispersion due to the residual flow plays more important role on the distribution of the material in the shallow bay, as Mikawa Bay, than the diffusion due to the tidal current itself.
ENHANCEMENT OF DIRECTIONAL WAVE SPECTRUM ESTIMATES
Authors: Panicker Narayana N. , Borgman Leon E.
Published: June 2019

Determination of the directional distribution of ocean surface waves is of practical importance and analytical schemes for it are developed and discussed here. Based on a generalized representation of wave properties such as surface elevation, subsurface pressure or horizontal components of water particle velocity, acceleration or wave force, two general schemes of analysis are developed. In one scheme the predictive equations for the directional distribution of both the amplitude and phase of waves are derived. Distribution of energy as a function of direction for random waves is obtained in the other scheme. Fourier series parameterization is used to represent directional spectrum. The truncation of the series dictated by data limitations introduce directional spread and negative side lobes for the estimated directional spectrum. A procedure to remove these undesirable side lobes by a non-negative smoothing function is described. The smoothing causes further directional spread. Methods for obtaining better directional resolution are discussed. Data adaptive spectral analysis techniques such as Maximum Likelihood Method and Maximum Entropy Method are suggested.
EFFECTS OF BANK RAISING ALONG THE THAMES
Authors: Bowen Anthony J. , Pinless Sally J.
Published: June 2019

A one-dimensional numerical model was used to estimate the location and volumes of water flooding over the banks of the Thames Estuary under several combinations of bank levels and possible storm surges. An assessment of the probable damage resulting from each of these floods enabled a comparison to be made between the various possible schemes for bank improvement and, indeed, showed that there was a serious need for such improvement even though a start on the construction of the Thames Barrier was imminent. In an estuary such as the Thames the overflow may provide a significant turn in the continuity equation and the effect must therefore be programmed as an integral part of the model; one obvious effect of the overspill is to limit the maximum levels to about 0.2 m above the banks in the upper Thames, almost irrespective of the size of the surge.
ENVIRONMENTAL ANALYSIS FOR BAHAMAS SUPERTANKER PORT
Authors: Harrison W.
Published: June 2019

From the point of view of the Bahamian environment, the most favorable locations for a supertanker port are 1) the western margin of the Great Bahama Bank, 2) the western shores of Grand Bahama Island and 3) the western margin of Little Bahama Bank. A port in any of these areas would a) usually be located down-wind and down-current of the majority of Bahamian islands and shallows, b) be located adjacent to boundary currents, expecially the Florida Current, that would tend to carry large accidental oil spills away from coastal areas and into the North Atlantic, c) be located where wave energies would be relatively low, and d) be positioned close to sea-lanes, obviating supertanker penetration of the central Bahamas. A site 30 miles east of Freeport, Grand Bahama Island, was chosen for construction of a sea-island supertanker bunker. Six controlled spills (270 U.S. gals, each) of crude and two spills of naptha were made at the sea island site during the windiest month (February). Slick spreading rates are presented. Cumene and all lower-boiling aromatics disappeared within the first 90 minutes after a crude-oil spill; a majority of toxic fractions (BP < 220°C) disappeared within 3 to 8 hours. Slick-drift roses for extreme-wind-persistence and strongest-coastal-current conditions indicate the environmental suitability of the site for capture and cleanup of small spills (< 1000 gals.).
ENVIRONMENTAL PROBLEMS ASSOCIATED WITH A PIPELINE LANDFALL IN COASTAL DUNES AT CRUDEN BAY, ABERDEENSHIRE, SCOTLAND
Authors: Ritchie William
Published: June 2019

The first oil pipeline from the North Sea area reached Scotland in 1973. The landfall, at Cruden Bay, Aberdeenshire, is a sediment-filled, bay-head beach with coastal dunes. Environmental and landscaping problems arose with the trenching of the beach and dune areas. Various methods, including flexible fence construction, spraying with a bitumen compound and spreading of soil over vulnerable areas, protected the site successfully. Full revegetation took place later and the beach and dune area are now restored to their original condition. Environmental management techniques were designed to preserve the high amenity and ecological status of the site and minimise the risk of side-effects, both during and after engineering work.
APPLICATIONS OF EMPIRICAL FETCH-LIMITED SPECTRAL FORMULAS tO GREAT LAKES WAVES
Authors: Liu Paul C.
Published: June 2019

Two episodes of Great Lakes waves for which both wind and wave data are simultaneously available are used to examine the applicability of the empirical fetch-limited spectral wave formulas developed by JONSWAP, Mitsuyasu, Liu, and Sverdrup-Munk-Bretschneider. Comparing the results hindcast from the formulas with those recorded shows that, for hindcasting significant wave heights, Liu's formula gives better results for less than fully developed Waves, while formulas by JONSWAP, Mitsuyasu, and Sverdrup-Munk-Bretsehnelder give better results for fully developed waves. In hindcasting average wave periods and peakenergy frequencies, all the formulas result in a deviation of up to 2 s and 0.5 rad s~*, respectively. These results can he used as a reference in evaluating and interpreting wave predictions made by these formulas as applied to the Greak Lakes.
MEASUREMENT OF INCIDENT WAVE HEIGHT IN COMPOSITE WAVE TRAINS
Authors: Sandstrom Ake
Published: June 2019

A method is proposed for measurement of the incident wave height in a composite wave train. The composite wave train is assumed to consist of a superposition of regular incident and reflected waves with the same wave period. An approximate value of the incident wave height is obtained as the arithmetic mean of the wave heights measured "by two gauges separated a quarter of a wave length. The accuracy of the method in relation to the location of the gauges and the wave parameters is investigated using linear and second order wave theory. Results of the calculations are presented in diagrams.
ORIGIN, EFFECT AND SUPPRESSION OF SECONDARY WAVES
Authors: Hulsbergen C.H.
Published: June 2019

Beach profile formation may be severely affected by secondary waves which, together with the basic wave, always originate from a sinusoidally.moving wave board The ascertainment of this experimental fact is followed by an investigation of the behaviour of the generated waves and their interactions It appears that the many characteristic features, among which the spatial beat phenomenon and the secondary crest formation, are generally in good accordance with the theories of Fontanet [I4j, and Kravtchenko and Santon I 20J It is concluded that an "outer" analysis, eg by plotting the x-tlines of visible peaks, is only of limited use to describe the "inner" character of the complex phenomenon. The subsequent study of the effect of secondary waves on a horizontal sand bed reveals that not only the wave form, but also the sand transport varies spatially, resulting in the formation of bars and troughs This typical behaviour of the onshore-offshore transport is provisionally investigated in a small pulsating water block. Finally, a method is described which suppresses the secondary waves, by using a low rectangular sill on the otherwise horizontal bottom.
TRANSFORMATION OF IRREGULAR WAVES IN SHOALING WATER
Authors: Sakai Tetsuo , Iwagaki Yuichi
Published: June 2019

In the numerical method of prediction of wind waves in deep water, Hasselmann's nonlinear interaction theory is applied. This method assumes the energy balance of individual component waves. However, the total energy balance must exist in the transformation of irregular waves in shoaling water. In this investigation, experiments were carried out on the transformations in shoaling water of composite waves having two components and random waves having one or two main peaks. It was found that the elementary component wave height of the composite waves and the elementary peak power of the random waves decrease with decrease in the water depth. This reason can be explained qualitatively by the theory of the elementary component wave height change of finite amplitude waves in shoaling water. The secondary component wave height of the composite waves and the secondary peak power of the random waves increase with decrease in the water depth. This can be explained qualitatively by Hamada's theory of nonlinear interaction in uniform depth.
FIELD INVESTIGATIONS IN SURF ZONES
Authors: Dette Hans Henning , Fohrboter Alfred
Published: June 2019

During storm surges considerable wave energies are dissipated in surf zones; the energy transfer rates are in the order of one up to two powers of ten higher than outside the surf zone. A breaker parameter s introduced by FOHRBOTER (1974) with regard to a quantitative breaker classification, especially of the intermediate types between surging and spilling, was found to be convenient for practical application. The breaker parameter e is in close relation with the horizontal asymmetry parameter a of the breaking wave. With decreasing breaker parameter the asymmetry is increased and reverse. Within the longshore currents macro-turbulences were discovered. The periodical fluctuation parameter y was found to increase nearly linearily with decreasing breaker parameter; the narrower the area is, where the main energy is dissipated the smaller becomes the mean periodical fluctuation which seems to be independent of the wave period but reaches up to 7 and more fluctuations within the wave period. The mean longshore currents velocities reached up to 1.5 m/s above the seabottom; th£ coefficient of variation was scattering considerably between 400 per cent at low velocities (v,= 0.1 m/s) and 20 per cent at the highest velocities (v.= 1.5 m/s). The instantaneous longshore current velocities were nearly symmetrically distributed around the mean velocity, the mean amplitudes were nearly constant and reached approx 0.35 m/s whereas the periodical fluctuation decreased from 2.6 s at low mean velocities up to 1.7 s at high velocities.
RESULTS OF OCEAN WAVE-CONTINENTAL SHELF INTERACTION
Authors: Goldsmith Victor , Colonell Joseph M.
Published: June 2019

Extensive wave refraction computations and analyses have been made utilizing eleven depth grids on the inner continental shelf along the east coast of the United States. The most important process determining shelf and shoreline wave energy distribution is the interaction of the ocean surface waves with the numerous shelf relief elements. This ocean wave-continental shelf interaction results in a non-uniform wave energy distribution that varies widely with different wave input conditions such as wave approach direction, wave length, and tide level. Techniques are being developed to manipulate and analyze these extensive wave data (encompassing over 500 wave refraction diagrams and associated computations), in order to increase understanding of the complex wave behavior resulting from the ocean wave-continental shelf interaction.
DIFFRACTION OF GRAVITY WAVES BY LARGE ISLANDS
Authors: Christiansen Peter L.
Published: June 2019

The combined refraction and diffraction of long gravity water waves for certain depth variations around large islands is investigated analytically in a circular-symmetric geometry. Creeping waves are shown to exist for bottom profiles less convex than required by the trapping criterion due to Longuet-Higgins and Shen et al. From an asymptotic representation of the solution to the scattering problem the decay exponent and the diffraction coefficient is extracted. These "canonical" quantities may then be used for the construction of diffracted fields around smooth islands of more complex shape in accordance with J.B. Keller's Geometrical Theory of Diffraction.
THE EFFECT OF WAVE REFRACTION OVER DREDGED HOLES
Authors: Motyka J.M. , Willis D.H.
Published: June 2019

Preliminary results are presented of a study of the beach erosion caused by wave refraction over offshore dredged holes. A mathematical model is used of an idealised sand beach, typical of those on the English Channel and North Sea coasts of Great Britain. Depth and side slopes of dredged area and original water depth before dredging were varied. Beach erosion increased with increasing hole depth and with decreasing original water depth. The effects of side slope and hole depth will be separated in future work, as will the effects of hole shape. Beach erosion due to holes in water depths greater than half the length of "normal" waves, or a fifth of the length of extreme waves, was negligible.
LONGSHORE CURRENTS AND WAVES AT BURULLUS COAST
Authors: Manohar M. , Mobarek I.E. , Morcos A.
Published: June 2019

Littoral currents within the breaker zone and currents other than those induced by waves beyond the breaker zone exist with considerable magnitude along the Nile Delta coast. Analysis of the littoral currents within the breaker zone by four semi-empirical formulae involving energy, momentum and radiation stress principles indicates good correlation between predicted and observed velocities. Galvin-Eagleson approach gives the best fit. Current data are statistically analysed enabling the determination of the magnitude, direction and percentage of occurrence of any particular littoral current for any particular period. More comprehensive studies of the currents climate within the breaker zone and beyond the breaker zone for the entire Nile Delta coast covering a large number of years are under way,