bluuebunny/crossref_metadata_2025 huggingface dataset:
COASTAL PROTECTION DEVICES - A REVIEW
Authors: Foster D.N.
Published: June 2019

Coastal protection devices include, but are not limited to, dune stabilization, seawalls, groynes, detached breakwaters, sand bypassing and beach nourishment. These are the "tools". The "rules" for their use comes from a knowledge of the beach processes which in many instances are site specific. Systems which work satisfactorily at one location may not necessarily work at another. A plan is made for authors to give more information on these processes when describing case histories. The variability of the physical conditions and the non-linear nature of many of the coastal processes often dictates how coastal protection works will behave; a fact which is not always taken into account by the designer. For coastal protection devices to be developed to their full potential requires improved instrumentation and data bases and a greater knowledge of the coastal processes than is available at the present time.
VARIATION OF FORESHORE DUE TO DETACHED BREAKWATERS
Authors: Toyoshima Osamu
Published: June 2019

As coastal areas are very valuable for mountainious Japan, many countermeasures against beach erosion have been taken. The length of seawalls for beach erosion amounts to 5,600 kilometers, which is much longer than the length of seadikes for flood tide, which is 2,900 kilometers. In addition, 10,000 groins and 2,300 detached breakwaters have already been constructed for beach erosion. Especially, we used many detached breakwaters for the last ten years. Fig.1 showes the increase of total length of seawalls and seadikes for the last twenty years.
RESULTS OF SHORELINE EROSION DEMONSTRATION PROGRAM
Authors: Edge B.L. , Housley J.G.
Published: June 2019

Very little has been done in the United States to assist the private landowner when his property has been threatened by coastal erosion. Primarily, efforts have been concentrated on large scale shoreline protection efforts which cover municipalities or large regions. These efforts have been basically Federal or large state projects. Between 1974 and 1980, the United States government conducted a national program to fill this void by demonstrating a low cost technology for shoreline defense. The objective of this paper is to report on the program itself and its results.
THE BEHAVIOUR OF PROTOTYPE BOULDER REVETMENT WALLS
Authors: Smith A.W. , Chapman D.M.
Published: June 2019

This paper reports the results of on-site observations of coastal revetment structures under extreme storm conditions on the Gold Coast of Australia. The Gold Coast is located at approximately Lat. 27° S on the East Coast of Australia facing the Tasman sea behind a narrow continental shelf and exposed to a relatively high energy wave climate as depicted in Fig 1. Tropical cyclones generate the highest storm activity on the Gold Coast with Ho values commonly exceeding 10m with the resultant onshore wave i.e. either the second or third wave reformed breaks within the range of 2.5 to 3.5m. Storm wave periods are usually between 8 to 18 seconds. The ocean beach on the Gold Coast, some 30km long has been receding since the early forties and this has resulted in the construction of nearly 20km of revetment walls to "protect" the rear beach. Whilst some walls in particularly erosion-prone areas were constructed in the 1920 decade, most have been constructed since 1967 which represented a particularly high cyclone prone year. Since the latter period the walls have been exposed to three further periods of high cyclone energy attack in 1972, 1974 and 1976. Nearly all revetment walls demonstrated at least some settlement and damage but over the three storm periods at least 0.8km of wall was completely destroyed. Most wall failures were monitored on site and whilst the construction of the walls varied in quality the observational results might well be classified as full scale prototype performance tests.
FLOATING TYRE BREAKWATERS - A CASE HISTORY
Authors: McGregor Robert C. , Gilbert Colin H.G.
Published: June 2019

The problem of achieving a system of coastal protection which is cheap, effective and reliable has stimulated the minds of researchers and innovators for many years. Although floating breakwaters have been written about since the 1840s, interest in them has increased rapidly in recent years. Over the last decade or so floating tyre breakwaters (FTBs) have received considerable attention. Several different designs have been proposed. Candle (1974) proposed what may be considered a nearly rigid mat of tyres where neighbouring tyres move relatively little with respect to one another whereas Noble (1976), Harms (1978) and Kowalski (1974,76) use breakwater flexibility in their wave-maze, PT and modular designs respectively. The breakwater described in this case history used the Kowalski or Goodyear design, which is made up of modules of eighteen tyres which are connected up to form a flexible mat (See Fig.l).
STATE OF THE ART IN TIDE PREDICTIONS
Authors: Zelter B.D.
Published: June 2019

By the end of the nineteenth century, scientists had succeeded in achieving the ability to make reasonably accurate tide predictions by the harmonic method (Schureman, 1941). Except for the building of larger and more sophisticated mechanical tide prediction machines using the harmonic technique, tidal mathematicians more or less rested on their laurels during the first half of the twentieth century; indeed, many scientists assumed there was no need for further tidal research. It is ironic that one of the very few geophysical sciences that already had acceptable methods of prediction should become the subject of significant improvement during the last half of this century. These improvements include: 1) least square analysis for all tidal constituents simultaneously, 2) response analysis and prediction, 3) extended harmonic analysis, 4) tidal measurements in deep water on the ocean floor, and 5) global numerical models of tides.
NON-LINEAR WAVE FORCES ON FLOATING BREAKWATERS
Authors: Niwinski C.T. , Isaacson M. de St. Q.
Published: June 2019

A non-linear numerical method for calculating wave forces on floating bodies has been developed by Isaacson (1981). The time stepping procedure is programmed for a computer solution, and an incident wave train is time stepped past a fixed two-dimensional rectangular breakwater. The influence of various input parameters on the accuracy of results is investigated, and optimal values of the parameters are determined. The optimal numerical parameters are used to generate force and transmission coefficient results, which are compared to the results of other published studies. The method is shown to compare favorably with other results, with the non-linear nature of the method being clearly demonstrated by the different force curves produced by varying the wave height.
A NUMERICAL MODEL OF WAVE/BREAKWATER INTERACTIONS
Authors: Austin D. Ian , Schlueter Roger S.
Published: June 2019

A numerical model has been developed to simulate breakwater response to wave impacts with special reference to armor unit behavior and breakwater stability. The model uses a finite difference hydrodynamic code to follow the wave impacts and determine wave forces upon the breakwater components. A discrete element code models the breakwater response and motions. The model rationale and numerical basis are followed by three examples used in this, the concept validation, stage of model development.
FACTORS OF SAFETY FOR THE DESIGN OF BREAKWATERS
Authors: Mettam J.D. , Berry J.G.
Published: June 2019

This paper proposes to improve the safety of breakwaters by two important changes in the philosophy of design. When hydraulic model testing is used as a design tool the authors propose to reduce the specific gravity of the model breakwater to introduce a factor of safety in the prototype. They also recommend that the concept of testing for stability with the once in 50 year or once in 100 year wave should be replaced by a more rigorous statistical analysis to determine a design wave which has a probability of exceedence of no more than 5% in the lifetime of the structure.
BREAKWATER STABILITY - BREAKING WAVE DATA
Authors: Carver Robert D. , Davidson D. Donald
Published: June 2019

The objective of the research presented is to furnish design information for stone and dolos armor on non-overtopping breakwater trunks that are subjected to severe depth-limited breaking waves. Since it would be a mammoth task to comprehensively investigate all the different types of existing armor, this particular research effort concentrated on stone, which is a natural and economical protection when it is of sufficient size and quality to meet design constraints, and on the dolos, which according to nonbreaking wave data is the best hydraulically stable concrete armor unit.
COMBINED WAVE-CURRENT FORCES ON HORIZONTAL CYLINDERS
Authors: Chandler B.D. , Hinwood J.B.
Published: June 2019

Some early results are reported from an investigation of the forces exerted on horizontal cylinders by waves and currents. It appears that the values of the inertia coefficients decrease as U/uQ increases, and the drag coefficients decrease also, for values of U/uQ up to 0.7. Comparisons with measured data show that linear theory and the stream function theory satisfactorily describe the wave motion for the conditions investigated, and that velocity superposition can be used with either of these theories to describe conditions involving waves plus currents, with reasonable accuracy.
ENVIRONMENT IN COASTAL ENGINEERING: DEFINITIONS AND EXAMPLES
Authors: Galvin Cyril
Published: June 2019

In current usage, environmental aspects of coastal engineering design include aspects of ecology and aesthetics, as well as environment. In practice, the aspect of environment is a limited one, considering man's surroundings, with the works of man left out. The increased consideration of environmental aspects over the past 15 years has brought real benefits to the coastal engineering profession, as well as obvious problems. One problem is a mythology of coastal processes that has become widely accepted. Priorities in coastal engineering design remain a structure that will last a useful lifetime and perform its intended function without creating new problems. After satisfying these fundamental requirements, the structure should minimize ecological change, and fit pleasingly in its setting.
STRUCTURAL DESIGN ASPECTS OF A COASTAL BUILDING CODE
Authors: Clark Ralph R.
Published: June 2019

Since 1957, the State of Florida, U.S.A., has witnessed the evolution of coastal regulatory concepts based upon coastal engineering design guidance. In 1978, the Florida Legislature encouraged counties and municipalities to adopt coastal construction zoning and building codes to supplement the existing minimum codes which include the Standard Building Code, the National Building Code and the South Florida Building Code. Subsequently, coastal building code guidelines were developed to provide statewide uniformity in the adoption of supplemental codes by coastal counties and municipalities. It is the intent of this paper to present the structural design aspects required in a coastal building code using the code guidelines developed for and specifically applicable to Florida's coastal communities. These same design aspects and code guidance are applicable to most other state's or nation's developable sand shorelines which are subjected to coastal storm damage. The purpose of a coastal building code in Florida communities is to supplement the existing minimum code by providing the structural design standards for construction within that portion of the beach and dune system which is subject to substantial scour, erosion, flooding, and loads accompanying the impact of a major hurricane. A coastal building code includes structural design standards for the construction of residential structures, enclosed commercial structures, coastal and shore protection structures, and other substantial structures of a semi-permanent nature. Although the few minimum codes currently in effect in the coastal communities are comprehensive for conventional construction, they do not adequately address the special structural design considerations identified for the Florida coast. Along a developable coast, special design considerations are necessary for the preservation of the beach and dune systems, as well as, for the structural adequacy of the construction. The major concepts of coastal engineering design which are necessary in a coastal building code include: 1. Zone identification (horizontal and vertical). 2. Foundation design for erosion and scour. 3. Storm loading (including wind, waves, hydrostatic, and hydrodynamic loads).
ENVIRONMENTAL AND ENGINEERING CONSIDERATIONS IN DESIGNING COASTAL WATER INTAKES
Authors: Hofmann P. , Mussalli Y.G. , Taft E.P.
Published: June 2019

Water intakes developed for coastal use often require special design considerations to ensure the incorporation of engineering features which are compatible with environmental protection. Due to the severity of the coastal zone environment, cooling water intakes for power generating facilities typically incorporate one of two possible designs: 1. A shoreline (surface) intake which could incorporate jetties, breakwaters, or inlet channels for wave protection and, when necessary, for retardation of sedimentary processes, or 2. An offshore, submerged intake connected via tunnel or pipeline to an onshore screen/pumphouse. Naturally, protection of structural integrity is of primary concern in designing and locating such intakes. Therefore, physical or hydraulic conditions are required to enhance plant reliability which may be adverse from an environmental viewpoint. As a result, it is often necessary to integrate additional provisions into intake designs which will mitigate potential adverse impacts resulting from plant operation. During the mid to late 1960s, as the size and number of power plants began to dramatically increase in the United States, various agencies responsible for protecting fish and wildlife were becoming increasingly alarmed that sport and commercial fisheries were being adversely affected by thermal discharges (Krenkel and Parker 1969). In response to this concern, various state and Federal regulations were promulgated to limit the effects of thermal discharges on aquatic biota. Various engineering options were developed to limit thermal effects. These options ranged from simply limiting the rise across the condenser, and therefore the ultimate temperature at the point of discharge, to employing various means of closed-cycle cooling, particularly at sites where water availability was limited (Parker and Krenkel 1969).
COASTAL ENGINEERING IN SOUTH AFRICA
Authors: Russell K.S.
Published: June 2019

The paper presents a review of the historical movement of ships around the South African coastline, traces the evolution and development of the harbours of South Africa, describes the development of coastal engineering and summarises the organisations and their activities in both basic and applied research projects contributing towards coastal works.
LONG WAVES OVER THE GREAT BARRIER REEF
Authors: Wolanski Eric
Published: June 2019

Low-frequency forcing of water currents over the continental shelf °f Australia is quite strong and should be taken into account when the flow for durations greater than 1 day is important. In the case of the Queensland coast, the longshore wind generates barotropic continental shelf waves, raising or lowering the mean sea level by as much as 30 cm and generating longshore currents over the continental shelf, even very close to the coast, that are often larger than the tidal currents. These wind-driven currents can reverse sign, flowing alternately northward and southward, although the longshore wind stress, though fluctuating, does not change direction. To reproduce such phenomena in an analytical or computer model of wind-driven currents, it is necessary to extend the offshore boundaries of the model offshore from the continental shelf break.
THERMAL IMPACT STUDIES FOR FRENCH COASTAL NUCLEAR SITES
Authors: Coeffe Y. , Clique P.M. , Manoha B.
Published: June 2019

The paper presents the different stages of the environmental studies performed at the Laboratoire National d'Hydraulique concerning some of the French coastal nuclear power plants using a once - through cooling system, and the different means used, in function of the proper caracteri sties of the site, to come to an optimum inlet-outlet configuration leading to a minimum thermal impact and to a minimum recirculation of the heated waters at the intake. The paper particularly describes the original studies performed for the Flamanvilie power plant where a special computer controlled tank has been used.
SALINITY INTRUSION INTO MULTI-PORT SEA OUTFALLS
Authors: Charlton John A.
Published: June 2019

Sea water intrusion into the diffuser system of a long sea outfall is likely to reduce the efficiency of the outfall. Recent surveys have revealed outfalls with a significant proportion of their diffuser blocked, and others discharging through as few as 50% of their diffuser ports. It is suspected that intrusion is the cause of these malfunctionings. Intrusion may be encouraged by the design requirement of low efflux velocities to obtain optimum dilution, or by over-design to cater for future increases in discharge. Although intrusion can only commence at low discharge velocities, when a port Densiometric Froude number falls below about 1, once it has started sea water will continue to enter the diffuser system until a state of balance is reached. Subsequently a considerably greater flow will be required to purge the outfall of all sea water. Intrusion may also be prematurely triggered by wave action, currents, or by reduced flow through a damaged port. Hydraulic model tests at the University of Dundee are leading to an understanding of the intrusion mechanism as it affects the various diffuser systems in current use. A continuing research and site survey programme is aimed at design recommendations to eliminate intrusion or reduce its effects.
DRIFT CURRENTS OF CLEAN AND SLICK SEA SURFACES
Authors: Wu Jin
Published: June 2019

Drift currents near sea surface govern movement and dispersion of man-made discharges near the sea surface, and influence design, deployment, and stability of offshore structures. The wind-induced drift currents and the wave-induced mass transports at the sea surface are separately estimated. The total surface drift current, the sum of wind- and wave-induced components, agree well with oceanic data (Hughes, 1956). The mass transport of waves over slick surface is greater than that over clean surface due to dynamic interactions between the surface film and waves. On the other hand, the wind-stress coefficient of slick surface is smaller than that of clean surface, resulting in a smaller wind-induced drift current over the slick surface. Available laboratory results (Alofs and Reisbig, 1972) on slick movements are reanalyzed to provide basis for estimating movements of slicks of various sizes over waves of different lengths under different wind velocities.
MARINE PIPELINE PROTECTION WITH FLEXIBLE MATTRESS
Authors: Crowhurst Alan D.
Published: June 2019

Development of oil and gas fields offshore presents new problems in the design of the civil engineering works since in many cases little is known about prevailing conditions on the bed of the sea over the considerable lengths involved. Movement of pipelines after construction, is, therefore, not uncommon and may result in the failure of the line. Consequent losses can be considerable. Pipelines are also vulnerable to mechanical damage by anchors and by fishing activities, the latter giving rise to political problems where the pipelines are laid across existing fishing grounds. To give protection to oil and gas pipelines as well as to marine outfalls and cables a method of protection has been developed using the well known concept of rock filled wire mesh or gabions. To adapt this method to use in underwater works another well proven material, sand mastic asphalt, has been combined with the gabion mattresses to give the required qualities of strength, durability, flexibility together with sufficient weight to restrain movement in the pipeline.
SEDIMENT TRANSPORT INVESTIGATIONS IN A NEW ZEALAND TIDAL INLET
Authors: Black K.P. , Healy T.R.
Published: June 2019

A study of sand and shell movement under the action of tidal flow was initiated in 1980 to ascertain the suitability of Whangarei Harbour at Marsden Point, New Zealand, for a proposed timber port. The aim was to assess the effects such a development may have on the sediment fluxes and the potential shoreline and channel instability that might be induced in the sandy inlet system. Vertical water velocity profiles were analysed to determine bed friction coefficients which were subsequently broken into two component parts: one due to form drag and the other associated with the skin friction. It was shown that the Vanoni and Hwang (1967) equation for form drag can be extrapolated to include drag under tidal flow over megaripples. The skin friction component was obtained from the speed at 1m above the bed and the De5 grain size, by utilising the Karman-Prandtl equation. This was applied to analysis of bedload trap yields and bedform advance rates over megaripples and good agreement with the Yalin bedload equation for plane beds was obtained. Suspended sediment transport was found to vary with U^7-75 and total load rates were in general agreement with the Engelund Hansen equation but deviations occurred due partly to expected form drag components being out of phase with the flow because of bedform hysteresis. Under tidal flow, the velocity at 1m was found to be a better predictor of sediment transport than the shear stress obtained from the velocity profile, thus methods presented in this paper use the lm speed for determination of total load transport.
ARTIFICIAL BREACHINGS OF BOT RIVER ESTUARY
Authors: Fromme G.A.W.
Published: June 2019

During the flood year of 1981 the "Bot River Vlei", one of the largest lagoons in the south-western Cape of the Good Hope was opened to the sea by two artificial breachings of the sand bar which were aimed at lowering the excessively high water levels in the lagoon, and at the re-establishment of estuarine conditions. The Coastal Engineering and Hydraulics Division of the National Research Institute for Oceanology of the CSIR surveyed and monitored the hydrological and sedimentological events in the Bot River lagoon and at the mouth channels in an attempt to formulate a future viable management policy, which had to take into account the conflicting interests of the defenders of continued artificial breachings and of those who advocate conditions of a closed estuary which will eventually change into a coastal freshwater lake.
INTERFACIAL AND BED SHEAR STRESSES IN SALINE WEDGES
Authors: Dermissis Vassilios , Partheniades Emmanuel
Published: June 2019

The shear stresses and the associated friction coefficients at the interface and at the bed of an arrested saline wedge have been studied experimentally together with the detailed flow structure. Interfacial stresses, evaluated from hot film anemometer measurements and actual velocity profiles, agree well with those based on the integration of the equations of motion while the simplified one dimensional analysis gave considerably higher values, It_was found that both the average interfacial friction coefficient, f and the average bed friction factor, f are best correlated with the dimensionless number, ReFr2, where Re and Fr are the Reynolds number and the non-densimetric Froude number of the flow respectively, and with the relative density difference, Ap/p, The results are presented in two families of curves with Ap/p as a parameter. The scattering of data points is minimal and the agreement with the results of some previous laboratory investigations and field data is good.
MORPHOLOGICAL REACTIONS OF TIDAL SYSTEMS DUE TO NEARSHORE CONSTRUCTION WORKS
Authors: Dieckmann R. , Partenscky H.W. , Schwarze H.
Published: June 2019

The nearshore region of the North German North Sea coast is characterised by a large area of tidal flats with a width of 10 to 30 km (Fig. 1) . The development of the structure of this coastal area in the past centuries was mainly determined by several severe storm surges, which have destroyed the formerly existing coastline. In its present state the coastal area is subdived into numerous tidal flats, islands and peninsulas of different size and more or less deep channels and small gullies. Due to its historical development, this area cannot be expected to be morphologically stable. Once people learnt to build safe dikes, the coastline existing at the time was fixed whilst the islands in the shore belt were protected against flooding during storm surges. However, the shore belt is furthermore exposed to waves and tidal currents which cause - apart from certain shlftings of gullies - extensive permanent erosion and sedimentation in parts of the shore belt with an increasing tendency in the last decades. The nearshore region at some places on the coast is extremely endangered in its function as part of the coastal protection system, consisting of the dike, the foreshore above MHW and the tidal flat area. First attempts to achieve morphological stabilisation of the nearshore region consisted in the construction of dams normal to the coastline. However, the shore belt still remained morphologically unstable and could not yet be transformed into a stable system.
DESIGN OF COASTAL STRUCTURES FOR RECREATIONAL PURPOSES
Authors: O'Connell G.H.
Published: June 2019

Although the major aspect of this paper deals with a specific part of the South African coast line it is believed that certain fundamental parameters which emerge are applicable to the greater part of the Southern African coast line of 2954 km. Typical of the African continent the nature of the Southern African coast line is regular and even with few bays or inlets and has long unprotected beaches subject to long- and off-shore current patterns. The absence of barrier islands as well as the few in number of protected lagoons and inlets, requires the creation of artificial tidal enclaves or the protection of selected sections of beach to ensure safe bathing conditions where further extensions of existing areas is indicated both by an increase in the population as well as changing socio-economic conditions which place access to the coastal recreation areas, as an increasing facility, to a steadily growing number of people. This need has been intensified in South Africa by the rapid urbanisation and socio-economic development of the rural population as well as the geographic dispersion of the population of which a high percentage lives at or near the coast. It is unfortunately so that the need to provide additional access to the beach areas exists in such areas where maximum exploitation of the beach frontage has already taken place and where new development must take place accordingly in less favourable conditions and subject to various constraints imposed by existing development in these areas. These constraints are inter alia the development of industrial areas right onto the beach front, urban area development on the beach front and sewage outfall works discharging raw sewage into the surf zone. The absence of an adequate inland area contiguous to the beach, forces planners to absorb an increasing part of the primary dune area to accommodate parking areas and other facilities required for the accommodation of the mass migration to the beaches.
THE RELINING OF SAICCOR'S EFFLUENT OUTFALL
Authors: Bernstein Mark , Ahrens Hugh P.L. , Smart Michael D.
Published: June 2019

This paper describes the method employed to refurbish an existing marine outfall which was deteriorating rapidly. It reviews the repair options that were available and how each was investigated and rejected until the best solution was obtained. Finally the execution of the project is described in detail through each stage to successful completion.
CIRCULATION OF TWO MULTIPASS ESTUARIES IN THE GULF OF MEXICO
Authors: Graham Donald Steven
Published: June 2019

An important class of estuaries which has received relatively little attention is the barrier-island-contained multi-inlet one. Cases range in scale from the tidal rivers common along the S.E. coast of the U,S.Ae to the very extensive embayments found on the Gulf of Mexico. A sound knowledge of the dynamics of the type of estuary is important for enlightened management of the resource. In the Gulf of Mexico region these estuaries tend to be significant spawning areas for marine fishes, and also support important local fisheries and oyster beds. Fortunately (or not) they are also geomorphically associated with coasts underlain by nearly-horizontal sedimentary rocks which often yield petroleum. Finally, in the Gulf of Mexico area of the U.S.A. the relatively attractive setting and climate of the barrier islands induces dense human development. (Surprisingly this attraction does not seem to occur in Latin America where the Gulf Coast is relatively unpopular and sparsely populated). Petroleum extraction and residential development, and the civil appurtenances needed to support them, can pose significant threats to the water quality, and hence marine life, of these estuaries. Local economic and social impacts can be severe since the fishing economy is usually marginal and traditional (even in the U.S.), while the oil and real estate businesses are usually strongly linked to wealthier portions of the exogenous economies. Because of this, regulation, is probably necessary to prevent excessive adverse impacts, and sound knowledge is required for proper and enforceable water quality regulation.
AUGMENTATION OF URBAN WATER BY ANTARCTIC ICEBERGS
Authors: Lawson J.D. , Russell-Head D.S.
Published: June 2019

The indigenous water resources of the south west of Australia are under increasing stress. One solution to this problem may be water importation in the form of Antarctic icebergs. This possibility is discussed in this paper. To be cost effective, an iceberg water scheme needs to provide water at less than A$ 0.14 kl-* from the reservoir, and at yearly volumes of the order of 10° m . A number of analyses of the selection and towing of icebergs have been given in the past but the offshore processing of icebergs has been somewhat neglected. A conceptual solution to the processing problem is given in this paper and cost estimates for the acquisition and processing of icebergs are given. Our analysis indicates that iceberg water may be a feasible and economical urban water augmentation system for yearly volumes greater than 2 x 10 m^. Further work on iceberg water augmentation is warranted.
A PROPOSAL FOR WAVE ENERGY CONVERSION NEAR CAPE TOWN
Authors: De F Retief G. , Prestedge G.K. , Muller F.P.J.
Published: June 2019

The South African wave energy program has been underway for several years and has included an analysis of the temporal and spatial distribution of wave energy along the full coast-line, determination of energy attenuation perpendicular to the coast-line at a site on the south western coast, and the development of a wave energy converter which is most suited to local conditions and requirements. The resource analysis has shown that the inshore power levels occurring along the south western coast are as promising as any elsewhere in the world. A bottom mounted, V-shaped wave energy conversion device driving an air turbine has been found to be most suited to prevailing conditions. The conversion characteristics of the device are presented, based on 1:100 scale three dimensional and 1:50 scale two dimensional model studies. Preliminary design studies of the proposed conversion system have underlined its potential viability as a cost effective supplementary source of power.
SHIP MOTIONS RELATED TO DEEP DRAFT CHANNEL DESIGN
Authors: Noble Scott
Published: June 2019

This paper discusses the investigation that the U.S. Army Corps of Engineers, Portland District undertook for possible modifications to the Columbia River entrance channel. Because of the characteristically high sea conditions at this location, wave induced ship motions were considered an important criteria to be evaluated. Phototype ship motion measurements were obtained along with wave data. The data and preliminary results are summarized. Emphasis is given to the analysis of a relationship between environmental conditions and vertical excursions, and the subsequent use of the relationship to determine a new channel depth.
WAVE-INDUCED SHIP MOTIONS IN HARBOUR ENTRANCES - A FIELD STUDY
Authors: Krueger A.C. van Wyk
Published: June 2019

Extensive field monitoring programmes were implemented to study the behaviour of deep-draught ships in the entrance channels to two major South African ports. These programmes form part of a study to assess the future accessibility of these ports to ships of greater draught. This paper describes briefly the monitoring techniques and methods of data analysis used, and reviews the results with regard to the environmental conditions during the monitoring operations. The prototype results on ship response to waves will provide valuable data for the calibration and validation of both mathematical and physical models. The results are also used to establish allowance criteria based on safe underkeel allowances for ships presently using these harbours.
THE RESPONSE OF SMALL CRAFT TO WAVE ACTION
Authors: Isaacson M. , Merger A.G.
Published: June 2019

A comprehensive study has been conducted for the Small Craft Harbours Branch, Department of Fisheries and Oceans Canada, to provide improved criteria for acceptable wave climate in small craft harbours (Ref. 3). An important part of the study was directed to model tests of vessel response to waves, and comparisons of these to field measurements and to simplified analytical predictions. The objective of the present paper is to describe these specific comparisons and present the corresponding results in the context of improving harbour entrance designs. The model tests results and theoretical predictions are adequate to show quantitatively the dependence of a sailboat's response to different wave lengths with sufficient accuracy for wave periods, heights and directions to be selected as variables in formulating the required wave criteria.
THE MOTIONS OF A MOORED SHIP IN A HARBOR BASIN
Authors: Sawaragi T. , Kubo M.
Published: June 2019

In harbors affected by ocean swells,cargo handlings are often interrupted and irooring lines are broken as a result of severe ship motionsl). In order to decrease such accidents, the noored ship notions in a harbor basin must be studied. In this paper the ship notions in the harbor basin are investigated by using three dimensional Green's function and close agreement between theoretical and experimental results can be found. New methods to reduce noored ship motion are also proposed. The efficiency of these methods is verified theoretically and experimentally.
UNUSUAL WAVES ON EUROPEAN COASTS, FEBRUARY 1979
Authors: Draper Laurence , Bownass T.M.
Published: June 2019

A depression in mid North Atlantic moved at a speed such that it generated high waves of unusually long period and large wavelength. These waves travelled in precisely the right direction to carry them into the English Channel, where they arrived during a time of spring tides and when low barometric pressure contributed to long waves impinging high, on the foreshore, causing appreciable damage to sea defences and property.
MEASUREMENTS OF TURBULENCE OVER VORTEX-RIPPLE
Authors: Sawamoto Masaki , Yamashita Toshihiko , Kitmura Tadashi
Published: June 2019

When a wave propagates over a rippled bed, organized vortices are generated over the leeside slope of crest. They are shedded, collapse and finally supply energy to turbulence in the vicinity of bed. This process plays an important role in the sediment transportation and suspension due to waves. However, quantative measurements of this phenomena have been limited because of some difficulties. Horikawa and Watanabe(1970) developed the electrolytic transducer and measured the turbulence over a rippled bed. Nakato, Locher, Glover and Kennedy(1977) used a hot-film anemometer controlled by a minicomputer and conducted a phase averaging sampling. One of the authors(1980) tried a phase averaging sampling of velocity field over an artificial ripple by a hot-film anemometer. Du Toit and Sleath(198l) used a He-Ne laser-Doppler anemometer to measure the velocity over artificial and selfformed ripples. Those are the principal contributions in this problem. One of the difficulties depends on a velocity meter. A hot-film anemometer which is widely used to measure turbulence in an unidirectional flow has some weakness under the circumstances of sediment suspension. Another difficulty lies on a data processing. Because the oscillatory flow turbulence is unsteady process, we can not utilize an analogue data processing technique which is very useful for a steady flow and are forced to handle a large number of digital data. In the experiments reported here, a laser-Doppler anemometer was introduced in order to overcome a first difficulty. The second one was solved by the combination of a wave-form-recorder-analyser and the desktop computer. The results show the good correlation of the turbulence variation and the movement of shedded vortices. Theoretical considerations on the time averaged turbulence are also presented.
WAVE AND CURRENT INTERACTION IN THE NEAR BED REGION
Authors: Kemp Patrick H. , Simons Richard R.
Published: June 2019

The question of how waves and currents interact, especially in the near-bed region is of considerable importance in relation to sediment suspension and sediment transport. Whereas empirical relationships provide useful estimates and indications in relation to the data on which they are based, a more thorough understanding of the physical processes at work is necessary for interpreting sediment transport behaviour in a more generalized way. Clearly the conditions under which flow reversal occurs near the bed, and also the extent to which wave motion may modify the current induced turbulence in the boundary layer, are both of great interest, and these and other aspects have been included in the present study. The research program was designed to look initially at the interaction between waves and currents in the absence of sediment, in order to define the mean velocity components, the structure of the turbulence, and the shear stresses. The study proceeded from experiments on waves alone, to waves propagating with the current and against the current. In all three cases the tests were carried out in the first instance with a smooth bed and subsequently with a rough bed consisting of two dimensional triangular slats. One of the main areas of interest was the height to which the water was disturbed above the bed when acted on by waves alone, and the comparable situation when a current was superimposed on the waves. Since the characteristics of the turbulent current were measured independently, it was possible to deduce whether there had been any interaction between the waves and the current, and also to infer what might happen to the distribution of the sediment which it was assumed would be put into suspension in the two cases. In the second stage of the research separate experiments were carried out in a standing wave channel and an oscillating water tunnel, using lightweight bed materials, in order to observe whether the inferences made from the clear water study were borne out by comparable changes in the distribution of the sediment in suspension.
EFFECT OF WAVE-CURRENT INTERACTION ON THE WAVE PARAMETER
Authors: Li Yu-Cheng , Herbich John B.
Published: June 2019

The interaction of a gravity wave with a steady uniform current is described in this paper. Numerical calculations of the wave length change by different non-linear wave theories show that errors in the results computed by the linear wave theory are less than 10 percent within the range of 0.15 < d/Ls s 0.40, 0.01 < Hs/Ls < 0.07 and -0.15 < U/Cs i 0.30. Numerical calculations of wave height change employing different wave theories show that errors in the results obtained by the linear wave theory in comparison with the non-linear theories are greater when the opposing relative current and wave steepness become larger. However, within range of the following currents such errors will not be significant. These results were verified by model tests. Nomograms for the modification of wave length and wave height by the linear wave theory and Stokes1 third order theory are presented for a wide range of d/Ls, Hs/Ls and U/C. These nomograms provide the design engineer with a practical guide for estimating wave lengths and heights affected by currents.
A FIELD STUDY OF WAVES IN THE NEARSHORE ZONE
Authors: Hotta S. , Mizuguchi M. , Isobe M.
Published: June 2019

Initial results are described of precise observations of waves shoaling in the nearshore zone. The key technique of the experiments is a 16 mm memo-motion camera system by which long term measurements of waves can be made simultaneously at many locations. Six or seven pairs of synchronized cameras were mounted on a research pier crossing the surf zone. The cameras were focused on target poles mounted on sleds which were towed about 200 m outside the breaker line, and on a line of poles jetted into the sea bottom across the surf zone. Waves transforming in the nearshore zone were observed from about 400 m offshore to the shoreline. At present only the characteristics of the statistical waves, wave height distributions, wave period distributions, and the joint distributions of wave height and period are described as part of the initial analysis.
INDIVIDUAL WAVE ANALYSIS OF IRREGULAR WAVE DEFORMATION IN THE NEARSHORE ZONE
Authors: Mizuguchi Masaru
Published: June 2019

In a field observation, water surface fluctuations were measured at many points on line from the shoreline to just outside the surf zone. The data were analyzed by an individual wave method, where the concept of primary individual wave is introduced in order to investigate irregular wave deformation. Primary individual waves are defined by applying the zero-down crossing method with a suitable band width at the zero level to the high-pass filtered water surface fluctuation. It is shown that a wave thus defined behaves like a regular wave with a fixed period in the nearshore zone. A deterministic model based on wave height change of monochromatic waves on non-uniform beaches is then introduced. The model is found to describe the observed deformation process expressed by the primary individual waves.
NEW EQUATION OF SURFACE ELEVATION IN WAVE MOTION
Authors: Ouyang Y.C. , Chen Y.Y. , Tang Frederick L.W.
Published: June 2019

A nonlinear solution of wave profile equation directly derived from stream function is submitted. In stead of expressing by trigonometric series to approach the real solution, implicit function is adopted. In the era of electronic computer, Such an expression wi11 be convenient for practical utilization. Equations in either deep water or in finite water depth are worked out. They are proved more reasonable in graphical shape of wave profile and consistent in the continuity of wave celerity in various depth in comparison with Stokes theory.
WAVE REFLECTION FROM UNDULATING SEABED TOPOGRAPHY
Authors: Weathershaw A.D.
Published: June 2019

The results of experiments are described which show that surface waves may experience a resonant interaction with undulations on the seabed. This interaction manifests itself in a strong reflection of incident wave energy when the wavelength of the bottom undulation is about half that of the surface wave. It is shown that such a mechanism might enable a region of undulating seabed topography (eg sand bars or sandwaves) to extend in an up-wave direction, into a region of otherwise plane bed.
WAVE HEIGHT DISTRIBUTION AND WAVE GROUPING IN SURF ZONE
Authors: Mase Hajime , Iwagaki Yuichi
Published: June 2019

The main purpose of this paper is to propose a model for prediction of the spatial distributions of representative wave heights and the frequency distributions of wave heights of irregular waves in shallow-water including the surf zone. In order to examine the validity of the model, some experiments of irregular wave transformation have been made. In addition, an attempt has been made to clarify the spatial distribution of wave grouping experimentally. Especially the present paper focuses finding the effects of the bottom slope and the deep-water wave steepness on the wave height distribution and wave grouping.
A FINITE ELEMENT METHOD FOR THE SHALLOW WATER EQUATIONS
Authors: Hauguel A. , Labadie G. , Latteux B.
Published: June 2019

The paper reports the current progress in developing a finite element method for the shallow water equations. The main feature of the method is the special care given to the advective and diffusive parts of the equations, so that it can be of interest to use it when dealing with flows strongly influenced by convective and boundary layer effects. The solution procedure has been chosen so as to allow a calculation with a big number of nodes. Section 3 of the paper outlines the method. In section 4, is detailed the procedure for the advective terms, involving the determination of the characteristic curves. Section 5 is devoted to the diffusion and propagation terms. Finally numerical results are presented in section 6.
COMPUTATION OF PARTICLE PATHS USING THE LAGRANGIAN LONG WAVE EQUATIONS
Authors: Savoie M.A. , Van de Kreeke J.
Published: June 2019

The Lagrangian long wave equations and the Lagrangian expressions for stress and strain are derived. Retaining the dominant terms the long wave equations are solved using an explicit finite difference method. Using the numerical solution, particle paths are computed for the tidal motion in a basin connected to the ocean by a single inlet. At the open boundary particle displacements are described. Computations are carried out with and without the Coriolis force and for linear and nonlinear bottom friction.
2- AND 3-DIMENSIONAL DETERMINISTIC FREAK WAVES
Authors: Kjeldsen Soren Peter
Published: June 2019

The present paper deals with a new non-linear technique for generation of violent breaking freak waves (plunging breakers) at specified positions and times in wave basins. First, results concerning generation of non-linear wave trains, Stokes-waves and wave solitons in deep water are given. Then the technique for generation of non-linear wave transients are given with specified non-linear dispersion properties. Finally, the new techniques are used to obtain collisions between non-linear solitons coming both from the same direction (2-dimensional case), and from different directions (3-dimensional case) leading to generation of steep and violent plunging breakers.
LABORATORY PHOTOGRAMMETRIC WAVE HEIGHT MEASUREMENT
Authors: Pos J.D. , Kilner F.A.
Published: June 2019

The paper describes the experimental procedure used to produce a computor contour plot of the wave height distributions and wave directions in a model basin, using photogrammetric techniques. Only monochromatic waves are analysed. A technique is outlined to simulate and measure waves entering a basin of infinite extent, in other words to photograph the penetration of a wave train into a harbour basin before the pattern has been contaminated by reflections. Proof is offered that this infinite basin technique is a valid representation of the steady state situation of a continuous wave train entering an infinite basin.