bluuebunny/crossref_metadata_2025 huggingface dataset:
COAST PROTECTION AGAINST THE ACTION OF WAVES AND CURRENTS
Authors: Mikhailov Leren P. , Uspenskii Sergei M.
Published: June 2019

According to the information available in the USSR,

now in the world there are more than 13000 reservoirs with storage capacity over 1 million m? in service and under construction. The largest ones are illustrated in Table 1. In some countries these storage reservoirs constitute rather a great per cent relative to all the reservoirs of the given country. (Table 2). Lately, such reservoirs have substantially grown in number in many countries of the world, especially in the USSR and USA, what is seen from the chart (Fig.1). In this connection, one can conclude on the great area of some reservoirs (reaching sometimes thousands of square kilometers), on their importance in the balance of the controlled runoff, making up in some countries over 95 per cent and on the intensive increase of their storage capacity beginning from the fifties of the present century. The above said is one of the reasons of greater interest in the action of waves and currents of the shore line showing up most intensively on the largest storage reservoirs. The length of the shore line of the USSR reservoirs is over 40000 km. The length of the erosion shores of storage reservoirs at the hydroelectric projects on the Volga and Dnieper River make up more than 30 per cent of the total shoreline of these reservoirs, while that of the reservoirs on the Kama River - 35 per cent. Most intensively the erosion is going on in the first decades of the operation of the reservoirs. The action of waves on the shore results in formation of the underwater slope with a gradient at which the wave energy is dissipated on the shoal, and the shore erosion slows gradually down until it ceases completely. However, it is rather difficult now to determine the period of the shore formation attenuation process in view of the fact that the problem of distribution of wave energy between all the phenomena taking place here is not properly studied yet and it is hot also clear what width and gradient of the shoal can fully baffle the wave energy and how much time it will take for such a shoal to get formed. The observation carried out on the natural water bodies well prove it.
FLOATING BREAKWATER PERFORMANCE COMPARISON
Authors: Harms Volker W.
Published: June 2019

Wave-transmission and mooring-force data of the Tethered-Float Breakwater and Pole-Tire Breakwater (PT-Breakwater) were compared, and the basic costs (without mooring system) of two equivalent breakwaters determined. It was found that, for short-fetch applications, the PT-Breakwater was an order of magnitude less costly than the Tethered-Float Breakwater. The PT-Breakwater is a more effective wave-energy filter than a Tethered-Float Breakwater of equal size. For open ocean conditions neither of these breakwaters has so far been proven to be economically feasible.
LONG-TERM EXPERIENCE WITH THE USE OF SYNTHETIC FILTER FABRICS IN COASTAL ENGINEERING
Authors: Heerten Georg
Published: June 2019

Various types of synthetic filter fabrics are available for geotechnical applications. Especially in the field of coastal engineering a lot of experiences are generally known. Unfortunately technical recommendations and testing regulations for specific implimentations of geotextiles are not generally available and some actual examples of damage of coastal structures urgently require investigations on long-term resistance. A research program oriented towards the development of guidelines for testing geotextiles, the development of filtration rules and the clarification of long-term resistance of fabrics was carried out. This paper deals with testing procedures associatied with the estimation of the opening size and the permeability to water of fabrics. Results of investigations on long-term resistance are described and filtration rules for selecting a fabric according to the special requirements of the application are given.
BREAKWATER WITH A SARD BITUMEN COEE
Authors: Loewy E. , Witthaus K.G. , Maddrell R.J. , Wood J.P.
Published: June 2019

Sand bitumen was used in the core of a rubble mound breakwater to form an impermeable barrier, essentially to inhibit the recirculation of warm water exhausted from a power station outlet back into the intake pumps. The core had a secondary advantage in permitting the placing of bitumen grouting to the rock on the lee face of the breakwater to stabilise it against wave overtopping. The paper describes the reasons which led to the adoption of this unique method on a very exposed coastline. It also outlines some of the measured properties of the sand bitumen and the methods used and experience gained in its mixing and placing. The sand bitumen, which has not to our knowledge been used for this purpose and as a core material previously, is proving to be successful.
MAJOR RECLAMATION SCHEME FOR MARINA CITY, SINGAPORE
Authors: Chew S.Y. , Wei J.
Published: June 2019

One of the most ambitious coastal reclamation projects in the Republic of Singapore to reclaim 360 hectares is now in progress and, when completed in 1985 at an estimated cost of S$385 million, will provide a major portion of the lands required for the development of Singapore's new city centre to be known as Marina City. This paper describes the various activities involved in the planning, design and construction of the project.
SHIP-BRIDGE-PIER PROTECTIVE SYSTEMS
Authors: Iwai Akira , Nagasawa Hitoshi , Oda Kazuki , Shoji Kuniaki
Published: June 2019

This paper describes the analytical and experimental studies on the behaviors of a ship subjected to a sheering flow induced around a rectangular solid-type marine structure, and also deals with ship-structure protective systems against ship impacts. Large bridge piers, which are constructed in a narrow waterway with strong tidal currents, are treated herein as one of the typical solidtype marine structures.
CAN WE DEVELOP NEW BREAKWATER ARMOUR FORMULAE?
Authors: Mettam John Dorrington
Published: June 2019

The purpose of this paper is to draw attention to the limitations of present empirical methods for the design of rubble mound breakwaters, particularly those using concrete armour units. Although it is unlikely that analytical techniques could become an adequate substitute for model testing, they should contribute significantly to a major advance in our understanding of breakwater behaviour. This is now long overdue and the art of breakwater design should be capable of substantial development.
EXPERIMENTAL INVESTIGATIONS OF PERIODIC WAVES NEAR BREAKING
Authors: Hansen J. Buhr
Published: June 2019

The results presented are from a series of experiments of periodic waves approaching breaking on a gently sloping beach. The recorded surface profiles are compared with a cnoidal theory taking into account the effect of the bottom slope. In both theory and experiments a skewness of the profile is observed. A fair agreement is found within certain limits of the wave height to water depth ratio and when the slope is sufficiently gentle. The change in water depth over a wave length must be sufficiently small. The detailed analysis of the surface profiles including the skewness element shows good agreement with the cnoidal theory in cases where the wave height variation is as predicted by cnoidal wave shoaling. The recorded surface profiles together with the recorded phase velocities are further used in computing the wave energy flux based on the theoretical relations from linear and cnoidal theories. Reasonable constancy is observed over the whole length covered by the experiments. Finally the recorded wave set-down is compared with the results of linear and cnoidal theories. When approaching breaking neither of the theories can apparently predict the recorded water level changes.
PORT OF BRISBANE SILTATION STUDY
Authors: Oud N.V.M. , Baxter T.
Published: June 2019

The paper describes the constituent parts of a combined field and mathematical model investigation into the processes causing siltation in the Port of Brisbane. It describes the methods of collecting and using field data and laboratory results in conjunction with a variety of mathematical models which were employed to simulate and predict the interaction of tidal and fluvial flows, saline intrusion and sediment transport in the Brisbane tidal river. A newly developed X-Z-T model was used to simulate the unsteady patterns of mud transport and siltation resulting from the interaction of tidal flows with short flashy fluvial floods, which are the main cause of shoaling in the Port. The paper discusses the structuring of the investigation which involved a carefully phased schedule of desk, field, laboratory and mathematical model investigations with the aim of solving the problem with minimum effort and cost. The paper does not discuss predictions.
THE USE OF ARRAY PROCESSORS FOR NUMERICAL MODELLING OF TIDAL ESTUARY DYNAMICS
Authors: Prandle D. , Funke E.R. , Crookshank N.L. , Renner R.
Published: June 2019

The use of array processors for the numerical modelling of estuarine systems is discussed here in the context of "hybrid modelling", however, it is shown that array processors may be used to advantage in independent numerical simulations. Hybrid modelling of tidal estuaries was first introduced by fiolz (1977) and later by Funke and Crookshank (1978). In a hybrid model, tidal propagation in an estuary is simulated by dynamically linking an hydraulic (or physical) scale model of part of the estuary to a numerical model of the remaining part in a manner such that a free interchange of flow occurs at the interface(s). Typically, the elevation of the water surface at the boundary of the scale model is measured and transmitted to the numerical model. In return, the flow computed at the boundary of the numerical model is fed directly into the scale model. This approach enables the extent of the scale model to be limited to the area of immediate interest (or to that area where flow conditions are such that they can be most accurately simulated by a scale model). In addition, since the region simulated by the numerical model can be extended almost indefinitely, the problems of spurious reflections from downstream boundaries can be eliminated. In normal use, numerical models are evaluated on the basis of computing requirements, cost and accuracy. The computer time required to simulate one tide cycle is, in itself, seldom of interest except in so far as it affects the above criteria. However in hybrid modelling this parameter is often paramount since concurrent operation of the numerical and scale models requires that the former must keep pace with the latter. The earlier hybrid model of the St. Lawrence (Funke and Crookshank, 1978) involved a one-dimensional numerical model of the upstream regions of the river. However, future applications are likely to involve extensive two-dimensional numerical simulation.
PARAMETER IDENTIFICATION IN ESTUARINE MODELING
Authors: Chu Wen-Sen , Yeh William W-G.
Published: June 2019

Parameter Identification (PI) algorithm is an optimization procedure that systematically searches the parameters embedded in a mathematical model. These parameters are not measurable from a physical point of view. The optimization is based on the minimization of a selected norm of the differences between the solution of the mathematical model and scattered observations collected from the system. Parameter identification (or inverse problem) has been studied in groundwater systems extensively for the past decade (15), and it has also drawn many researchers in the fields of open-channel flow and estuarine modeling since 1972 (1,2,9,17). All the past estuarine PI works in the literature are confined to the one-dimensional case, and hydrodynamics and transport equations are treated separately. This study deals with PI in a two-dimensional vertically-averaged estuarine salinity model. The salinity transport equation is coupled with the hydrodynamics equations. The coupled relationship introduces extra density terms in the hydrodynamics equations, which must be solved simultaneously with the transport equation. One of the most difficult problems in PI is the collection of needed observations from the system which is being modeled. With limited exception, the currently available data from the prototype estuaries are not adequate for the purposes of developing a PI algorithm. This is usually critical in quantity (the number of stations and/or the period of time) and in quality (noise of data). However, if an operational hydraulic model is available, the data could then be obtained economically and accurately under an ideally controlled environment. The large amount of data that can be collected from a hydraulic model of an estuary will provide a sufficient number of observations and the required initial and boundary conditions for the development of a PI algorithm. The use of the estuary hydraulic model could provide a better source of prototype data than would be available from the real estuary. It will be much easier to distinguish between the inadequacy of the mathematics and the inadequacy of our understanding of the prototype. Thus, it will give us an idea of how well we could expect to mathematically model the real estuary if we had an unlimited amount of prototype data. Additionally, when these types of data are used in PI, parameters can be optimally identified and the mathematical model can then be used conjunctively with the hydraulic model for prototype applications, provided that the mathematical model is consistently formulated. How well a hydraulic model simulates the prototype estuary is not considered in this study.
AUTOMATIC CALIBRATION OF NUMERICAL TIDAL MODELS
Authors: Holz K.P. , Januszewski U.
Published: June 2019

Numerical models for the simulation of tidal waves in estuaries have "become a standard tool of coastal engineers. Before they can he applied to practical problems, they have to be calibrated against nature. The basis for calibration is normally a representative set of tidal curves (natural field data), which has to be reproduced by the numerical model. Generally, the calibration is performed by empirically tuning certain parameters, until a fairly good agreement between measured and calculated quantities is obtained. In most cases, this is a "trial-and error" process which may become very time-consuming, and which strongly depends on the intuition and experience of the user. In order to make the process of calibration more effective, and to ensure that the best possible agreement between nature and numerical model is achieved, a calibration method has been developed to determine the parameters of the numerical model automatically by means of a mathematical method of optimization. The method is applied to a one-dimensional numerical model of the Elbe River.
INLETS/ESTUARIES DISCHARGING INTO SHELTERED WATERS
Authors: Riedel H.P. , Gourlay M.R.
Published: June 2019

Tidal prism - cross sectional area relationships and tidal velocities have been measured for inlet entrances and along the length of the estuary for four creeks entering the sheltered waters on the South East Queensland coast, Australia. It has been found that the inlet entrance tidal prism - cross-sectional area relationship is controlled by the magnitude of littoral drift. The tidal prism - cross-sectional area relationship along the estuary is believed to be common to all tidal estuaries landward of the region where littoral drift has an influence. For tidal inlets on sheltered coasts with tidal prisms of the order of 10 n~, the mean maximum velocity entrance is about 0.3 to 0.4 m/s.
DYNAMIC SIMILARITY OF TRANSPORT PHENOMENA
Authors: Yalin M.S. , Gerritsen F.
Published: June 2019

The discharges issued by OTEC plants, thermal power plants and other engineering devices, give rise to the transport of "foreign" properties and substances into the natural ocean environment. In order to predict the functioning of such structures and assess their environmental impact, physical modelling has already been utilized. Since the simultaneous fulfillment of both Reynolds and Froude criteria is impossible (in a conventional small scale model operating with the prototype fluid) in the models mentioned the transport phenomenon was reproduced on the basis of the densimetric Froude number (Fr) only, the influence of the Reynolds number (Re) being neglected. On the other hand, the identification of the scale of Fr (viz Apr) with unity can lead to substantial differences between the model and prototype values of Re. (Because AFr = 1 yields AR6 = Ax 3/2 where Xjt is the linear model scale.) Yet many of the pertinent aspects of a turbulent diffusion (energy dissipation, thickness of mixing zones, separation processes, etc.) are strongly dependent on Re, and therefore an appreciable distortion of Re (AJJ3/2
NUMERICAL MODELLING OF NEARSHORE CIRCULATION
Authors: Ebersole Bruce A. , Dalrymple Robert A.
Published: June 2019

Waves impinging on beaches induce mean flows, such as longshore and rip currents. This nearshore circulation is of fundamental importance in the study of the transport of nearshore contaminants as well as littoral materials. Analytic models of this nearshore flow {see, e.g. 4, 9, 11, 12) have been constrained to be linear (in the governing equations) and simplistic in the bottom topography. Only recently have numerical models been developed to examine more complex situations. Steady state, finite difference models (1, 14), as well as a finite element model (10), have been proposed. The numerical model, developed by Birkemeier and Dalrymple (1), allowed for time dependency. Yet, in all of these cases, the governing equations have not included the nonlinear convective accelerations or lateral mixing terms. In this study, a nonlinear numerical model is presented based on a leapfrog finite difference scheme, which includes time dependency and eddy viscosity terms. Results are shown for a planar beach showing a comparison with the analytical longshore current models (with and without lateral mixing) of Longuet-Higgins (11, 12). The longshore current over a prismatic beach profile including an offshore bar is presented next, showing the effects of the bar on the velocity profile. The circulation set-up by a rip channel inset into a plane beach is then computed. A comparison is made to the linear model of Birkemeier and Dalrymple. Finally the model is applied to the case of synchronous intersecting wave trains (4). An interesting result occurs when the waves are of different amplitudes, which could provide an explanation of the formation of finger bars on a beach.
HYDRAULIC CIRCULATION PERFORMANCE OF A CURVILINEAR MARINA
Authors: Layton Jeffrey A.
Published: June 2019

An innovative coastal engineering concept has been developed to maximize the hydraulic circulation and water quality of dredged backshore harbors and boat basins. The concept represents a radical departure from the hydraulic design of existing artificial boat basins in that the basin geometry and entrance channel are primarily sized for hydraulic purposes rather than navigational access. Specific elements of the concept are described below.
THE EFFECT OF BREAKING WAVES ON THE MIXING OF LIQUID POLLUTANTS INTO THE SEA
Authors: Naess Arvid
Published: June 2019

Experience gathered during the last few years shows that a serious problem when fighting oil spills out in open waters, is the mixing of the oil into the sea by breaking waves. In this paper we propose a theoretical model that we believe represent a fruitful approach to the problem of determining the amount of oil mixed into the sea by breaking waves. Our model is based primarily on probabilistic methods, but with experimental observations and data as an essential foundation.
DISPERSION OF COOLING WATER FROM A COASTAL LNG PLANT
Authors: Ackers P. , Pitt J.D. , Thompson G. , Rippin K.G.
Published: June 2019

The object of this case study was to predict the likely degree of pollution resulting from the discharge of heated water from a proposed LNG plant into the sea (Figure 1). The expected thermal loading was 40 m-Vs at a temperature of 10°C above the natural ambient sea water temperature. The investigation was required to provide data for an ecological study to determine the possible impact of the plant on the coastal and marine environment. Information on tide levels, tidal currents, salinity, sea temperature, wind strength and direction was obtained in a general survey programme which had already been commissioned. These data provided vital information on seasonal variations in marine conditions and further local information was obtained from short intensive hydrographic surveys. The data were analysed to yield a simplified description of the tidal and wind induced currents and suitable values of mixing parameters for use in two numerical models. The first dealt with the "near field" processes of the spread of a buoyant layer of heated water under the convecting influence of the tidal currents. The second model simulated the "far field" processes which give rise to a general increase in the temperature of the sea in the region.
DESIGN OF AN INTERMITTENTLY OPERATED OUTFALL
Authors: Lindquist Roger W. , Murphy George J.
Published: June 2019

The City of San Francisco, California, has a combined sewer system that presently overflows into the bay or ocean when it rains. Under the current wastewater management program being implemented, this combined flow of storm and sanitary wastes will be treated and discharged into the Pacific Ocean through a three-pipe outfall system. The system will dispose of the treated sanitary wastewater (dry weather flow) through a 2740-millimetre-(mm)-diameter, 6-kilometre (km) ocean outfall, and the mixture of sanitary wastewater and stormwater (wet weather flow) will be disposed of through two 2740-mm-diameter outfalls, 4 km long. The depth of the dry weather diffuser is approximately 24 m and the depth of the wet weather diffuser is approximately 17 m. The wet weather outfall will operate only when the rain exceeds 0.5 mm per hour. Rain exceeds this intensity about 4 percent of the time, or 350 hours per year. The peak wet weather flow is approximately 1800 megalitres per day (Ml/day)3. The average dry weather flow is 400 Ml/day and the peak dry weather flow is approximately 700 Ml/day. This paper reviews the unique problems of an intermittently operated outfall located in an area of shallow water with loose bottom sediments on a coast subjected to high wave energy. The circulation of seawater through the dormant diffuser and the resulting reduction in hydraulic capacity by sediment intrusion and biofouling are identified as the most severe problems for the intermittently operated outfall. The features incorporated to reduce these problems are bottom-exiting risers, diffuser ports elevated above the seabed, four ports per riser with a dual valve system, and use of antifouling materials and a flushing system.
EXPERIMENTAL EVALUATION OF HEAT EXCHANGE BETWEEN WATER SURFACE AND ATMOSPHERE
Authors: Barg Gunther , Schwarze Horst , Visscher Gerhard
Published: June 2019

The heat balance of a water body mainly depends upon the heat exchange processes at the water surface. An experimental method has been developed for determining the heat exchange, the exchange coefficient and the equilibrium temperature. The measuring equipment consists of two similar, well insulated pools which are exposed to the meteorological conditions of the Lower Weser River, Germany. The water temperature of the first pool (Ti) is artificially adjusted to the actual river temperature either by cooling or heating. The temperature of the second pool (T2) is held constant above the temperature T-| . The difference in power inputs required W2 - W-j is equivalent to the net rate of heat exchange due to the increase of temperature to AT above the river temperature.
DYNAMICS OF SILT IN ESTUARY, RESIDUAL CURRENT OR FLOCCULATION WHICH PREVAILS?
Authors: Lepetit J.P. , Davesne M.
Published: June 2019

The transport of fine suspended sediment in a partly-mixed estuary has been simulated on a physical model of a schematic estuary reproducing the main geometrical and hydrodynamical characteristics of the Gironde Estuary (France). The natural sediment consisting of silt and clay is simulated using a light and fine material, gilsonite, and the flocculation-'processes in salt water and under turbulence induced by tidal currents have been reproduced by adding in salt water a flocculating salt solution (sodium pyrophosphate). Then the formation of the turbidity maximum surveyed in the field and its upstream-downstream migration in response to varying river discharge have been successfully simulated and the results of different series of tests lead to the following conclusions : - flocculation processes - which are responsible of the variation of the settling velocity with salinity and turbulence-have to be reproduced to explain the formation of the turbidity maximum ; - after high river discharges the convergence of bottom residual currents (null point) due to the salinity intrusion creates a trap for suspended sediments supplied by the river flood which accumulate in the form of the turbidity maximum. Without salinity intrusion, a large amount of sediment would escape out of the estuary to the sea ; - during low river flows, a part of the suspended sediment migrates upstream but the amplitude of this migration is small compared with the displacement of the upstream limit of the salinity intrusion ; - the upstream migration of the turbidity maximum-is increased when a transverse bottom morphology (existence of a deeper navigation channel) is represented.
FOR DISPOSAL: 10 M.cu.m. OF CALCIUM CARBONATE SLURRY
Authors: Summers L. , Fleming C.A.
Published: June 2019

Construction of the Jebel Ali Port complex, 35 km southwest of Dubai, in the United Arab Emirates, has included the disposal of 110 Million cubic metres of excavated spoil. Disposal of dredged carbonaceous breccia raised particular problems due to the high proportion of fines generated and which, unless properly controlled, could cause wide scale environmental damage in the coastal zone. At the same time it was necessary that acceptable reclamation should be created. An extensive data collection exercise was carried out in order to monitor the geotechnical, hydraulic, meteorological, marine climate and marine biology aspects of the operation.
THE GERMAN "MORAN" PROJECT
Authors: Siefert Winfried , Barthel Volker
Published: June 2019

The project "MORAN" (Morphological Analyses of the North- Sea-Coast) is an extensive program in order to try and combine all knowledge of the morphologic behaviour of a transitional zone of 5 to 7 km width with weather, tide, current and wave data. The area to be considered is about 9000 km2 size. The program started in 1979 and will probably continue until 1984.
On the Synthesis of Realistic Sea States
Authors: Funke E.R. , Mansard E.P.D.
Published: June 2019

Recent investigations by some researchers (Johnson et al, 1978; Burchart, 1979; Gravesen and Sorensen, 1977) have indicated that it is no longer sufficient to match the variance spectral density of a simulated sea state to that of the prototype. When testing models of various fixed and floating structures, it appears to be most important to simulate the wave grouping phenomenon as veil. Some researchers also believe that the wave steepness, the particular sequencing of high and low waves (Burchart, 1979) and the ratio of the maximum to the significant wave height within a wave train are also of significance. Methods for the generation of 'random1 waves throughout the world vary greatly. One may, however, categorize these in terms of two substantially different approaches. These may be referred to as "probabilistic" on the one hand and "deterministic" on the other. In the former, a random or pseudo-random noise source is used which will never repeat or which has a very long repetition period. The assumption is then made that, in the course of the long testing period, all possible outcomes of wave heights, wave periods and wave groups will occur. The only constraint, which is usually placed on the synthesis, is the shape of the variance spectral density and its zeroth moment. The "deterministic" approach, on the other hand, attempts to create very specific and typically extreme conditions. Subsequent analysis of structural response to these conditions must, of course, be related to the likelihood of these conditions occurring in the prevailing climate. The old standby method of testing with monochromatic waves is a typical example of this category. However, other technigues such as Funke and Mansard (1979a) and the reproduction of prototype wave trains as favoured by several laboratories (Gravesen and Sorensen, 1977) may also be described as deterministic.
A COMPARISON OF NATURE WAVES AND MODEL WAVES WITH SPECIAL REFERENCE TO WAVE GROUPING
Authors: Burcharth Hans F.
Published: June 2019

This paper represents a comparative analysis of the occurrence of wave grouping in field storm waves and laboratory waves with similar power spectra and wave height distribution. Two wave patterns - runs of waves and jumps in wave heights - which have significant influence on the impact on coastal structures were included in the analysis of storm wave records off the coasts of Cornwall, U.K. and Jutland, Denmark. Two different laboratory wave generator systems, based on random phase distribution of component waves, were used. Within the limitations given by the relatively small number of analysed records it is shown that wave group statistics can be satisfactorily reproduced by random phase generators that are not based on a limited number of component waves, but for example based on filtering of white noise. It is also shown that the statistics of large waves and wave groups containing large waves depend on whether the waves are defined from zero-upcrossings or zero-downcrossings. Although very similar seas were chosen for the analysis it was found that significant differences in the wave group statistics from the two locations existed. Also a considerable scatter in the wave group statistics throughout the storms was found.
WIND WAVES TRANSMISSION THROUGH POROUS BREAKWATER
Authors: Massel Stanislaw R. , Butowski Piotr
Published: June 2019

Rubble - mound breakwaters are designed to protect exposed marine areas from excessive wave activity. The resulting interaction of the incident waves with the rubble units is extremely complex due to the variable reflective and frietional properties of the permeable structure. In the past decade considerable effort has been expended to derive rational methods for of such type structure. The theoretical and experimental investigations have been focused especoialy on the prediction of the reflection and transmission of regular waves incident to breakwater. Sollitt and Cross /^^^Z/ presented the analytical approach to the problem based on the assumption that the original nonlinear governing equation of the wave motion into porous media may be replaced by a linear one so as to give the same average rate of dissipation/Lorentz approximation/. Under the assumption that severe wave conditions for most breakwaters correspond to relatively long waves, the considerably simple solutions were developed by Kondo and Toma /1972/ and in series of papers by Madsen and co-authors /\97k, 1977, 1978/. Madsen s solutions follows rather a physical than mathematical rigorous approach to the problem. The momentum equation evaluated him explains the influence of the inertia force associated with the unsteady flow around the solid particles. Very careful analytical examination of this problem for the long waves past the narrow gaps and holes has been presented by Mei at al. /197**/. The study indicate that apparent mass term can be ignored in most practical cases.
SOME RECENT RESULTS FOR WAVE INDUCED MOTIONS OF A SHIP IN SHALLOW WATER
Authors: Madsen P.A. , Svendsen I.A. , Michaelsen C.
Published: June 2019

The paper describes an analytical approach to the problem of wave induced oscillations of a long ship in water with a depth which is only slightly larger than the draught of the ship. The problem is linearized (i.e. small amplitude motions and waves) and the water flow induced by the incident waves, and by the motion of the ship is determined. This also yields results for the forces in the equations of motion for the ship. These equations can be solved analytically, but the paper concentrates on giving numerical results for the solutions. Results are also given for the hydrodynamic masses and movements of inertia, and for the damping due to radiation of wave energy.
DISCRETE-TIME MODELLING OP DISPERSION IN ESTURARIES
Authors: Wood T.
Published: June 2019

This paper aims to put forward a case in favour of a simple discretetime model describing mixing in an estuary. The model derives from the remarkably simple concepts developed by Ketchum (1951 a,b) which describe mixing in terms of tidal prism exchanges between segments. The author's view is that Ketchum1s ideas were abandoned before they were fully explored. A major factor was the advent of the high-speed computer which opened up the possibility of using an approach based on the space-time formulation of the problem in terms of the partial differential equations of transport theory. Intrinsically this approach, based on a continuum description, is more attractive than a gross description based on relatively large segments: one obvious reason is the possibility of providing a comprehensive space-time prediction of the spread of a pollutant. In practice, though, significant problems arise in its use: in particular, the following can be mentioned - a) substantial computing costs relating to computer program development and machine time b) specification of transport parameters inherent in the partial differential equations of transport: for example, dispersion coefficients c) model validation and state/parameter estimation. The last of these is the primary concern of this paper. It is probably true to say that, to date, too little attention has been given to these topics, in the context of estuarine modelling. The point to be made is that there is small justification in using a sophisticated description of a system if the resulting predictions of the model cannot be effectively validated. The ideas used in this paper stem from those put forward by Beck and Young (1975) in studies on non-tidal river pollution. The subsequent discussion suggests an extension to estuarine systems-.
MEASUREMENTS OF OSCILLATORY DRAG ON SAND RIPPLES
Authors: Lafquist Karl E.B.
Published: June 2019

Measurements have been made of drag on naturally rippled sand beds in an oscillatory-flow water tunnel. A partition splits the tunnel into two parallel channels with equal cross sections and volume rates of flow, one with a smooth flat rigid bottom and the other containing the sand bed. Roughly, the difference in the two bottom drags, the one known, is equal to the difference in the net pressure forces on the water in the two channels, which is obtained from measurements of pressure differences across the partition at each end of the sand bed. Each experiment provides the drag, or average bottom stress, on the rippled sand bed as a function of the phase, 6, of the sinusoidal flow. From a first set of thirteen experiments with a medium sand, a stress coefficient, f(0), is presented in three families of curves which explore the additional effects of flow velocity, ripple length, and deviations of the ripple profile from normal equilibrium. Average rates of energy dissipation are calculated. Results show f to be a complicated function of 0 and other parameters. In particular, the instantaneous stress is not simply related to the instantaneous velocity. Some salient features of f(0) are described, qualitatively, by a simple model.
ACCURATE NUMERICAL SOLUTIONS FOR NONLINEAR WAVES
Authors: Fenton J.D. , Rienecker M.M.
Published: June 2019

This paper describes numerical methods for the accurate solution of the nonlinear equations for water waves propagating on irrotational flow over a horizontal bed. Fourier approximation is used throughout. Firstly, the problem of waves propagating without change is considered, giving a set of nonlinear equations which may be conveniently solved by Newton's method. It is emphasized that the usual specification of water depth, wave height and wave period is not enough to solve the problem - an assumption as to wave speed or,mean current or mass flux must be included. Comparing results with previous theoretical and experimental results, good .agreement was obtained. In the second part un^ steady wave motion is examined, and a numerical method proposed for studying the evolution of unsteady disturbances. This is applied to the case of a solitary wave being reflected by a vertical wall. Close agreement with experimental results is obtained. In addition, design criteria for force and moment on the wall are suggested.
SOURCES OF MEASURED WAVE DATA
Authors: Draper Laurence
Published: June 2019

A Catalogue listing 550 known sources around the world of instrumentally-measured wave data has been prepared by the Marine Information and Advisory Service under the auspices of the Intergovernmental Oceanographic Commission of UNESCO.
WAVE HINDCASTS AND MEASUREMENTS BASS STRAIT
Authors: Silbert M.N. , Barnett T.P. , Peters O.J.H. , Hamilton R.C.
Published: June 2019

The Bass Strait of Australia is the location of significant offshore oil and gas production. At the time of this writing eight self-contained drilling and production platforms as well as many miles of submerged pipeline comprise the Esso Australia Ltd. (EAL) and Broken Hill Proprietary Company Ltd. (BHP) operation in the Bass Strait. During the course of the next five years significant additional development and platform construction will take place in this offshore oil and gas area. Observation of offshore wind and wave conditions are greatly facilitated by the presence of fixed platforms from which to collect data. Visual observations of waves along with measurements of wind speed and direction and barometric pressure from Bass Strait Platforms have been routinely recorded and reported to the Australian Bureau of meteorology for more than ten years. Close cooperation between EAL and the Meteorological Bureau has resulted in continuous weather forecasts for the Bass Strait region. In March of 1977 EAL decided to upgrade the instrumentation on two of the platforms in the Bass Strait. The purpose of this was to reduce the subjectivity of visual wave observations and to eliminate the uncertainty of such observations at night and during inclement weather. Additionally it was felt that by instrumenting both a deep water (250 feet) and a shallow water (150 feet) platform the data collected would help quantify the observation that the storm waves seemed to be larger in deeper water than in shallow water. It was felt that use of the data along with a computer based wave hindcast model would aid in the development of an understanding of the Bass Strait wave environment. Two platforms were chosen for instrumentation. The Barracouta (BTA) platform in 150 feet of water, located about 20 miles from shore, was instrumented with a wavestaff. The Kingfish B (KFB) platform in 250 feet of water, located about 50 miles southeast of BTA, was instrumented with a wave staff, electromagnetic current meters, anemometer, barometer and air temperature sensor. Figure 1 shows the location of these platforms in the Bass Strait. The design, fabrication and installation of the data station was performed by Evans-Hamilton Inc. of Houston, Texas.
REALTIME WAVE ANALYSIS, NEWCASTLE, AUSTRALIA
Authors: Lawson N.V. , Youll P.H.
Published: June 2019

The Port of Newcastle, N.S.W., Australia, is being deepened from 11m to 15.2m below chart datum to permit the navigation of 12 0,0 00 D.W.T. bulk coal vessels. Part of this project, which is expected to reach a cost of approximately A$9 0 million, involves the removal of two million cubic metres of rock, some of which is located outside the breakwaters and exposed to ocean waves (see Fig. 1). Drilling and blasting of rock in the area subjected to ocean wave activity is being carried out by two self elevating platforms. On completion of drilling and prior to blasting the platform must make a transition from being supported by its legs to floating so it can be removed from the blasting area. While the two self elevating platforms have been built with a very fast jacking rate of 6m/ minute, with a sophisticated shock absorbing system connecting the legs to the platform, the rigs cannot be j acked up or down when wave conditions exceed a certain limit. Even though the rigs can survive worse conditions than those allowable for jacking down by remaining on their legs at a sufficient height above the water, this would entail loss of drilling time, and the presence of the rigs in the channel could close the port to shipping. Thus from an operational point of view it is vital that present wave conditions are reliably described. Estimation of wave height by observation is difficult enough during daylight hours but is virtually impossible in darkness (drilling operations are carried out 24 hours/day). The dredging contractor (WestHam Dredging Co. Pty. Ltd.) therefore decided that a real time wave analysis system should be established and co-operated with The Maritime Services Board of N.S.W. in a joint project for this purpose.
FLORIDA COASTAL DATA NETWORK
Authors: Howell Gary
Published: June 2019

The application of wave and tide data to coastal engineering problems has been demonstrated frequently by university and government research organizations. However, problems faced by practicing coastal engineers are often solved without recourse to such data, since it is frequently not available for the required location. The high cost and low reliability of long term wave measurement is the primary factor limiting the wider application of analysis techniques requiring wave energy and wave direction parameters. In order to improve this situation several organizations, notably the Army Corps of Engineers, Coastal Engineering Research Center (CERC), Peacock (1974), and the California Department of Navigation and Ocean Development, Seymour (1976), have employed advanced electronics and computer techniques to reduce the cost of wave measurement. The Florida Coastal Data Network (CDN) is a similar effort which due to the special problems of Florida wave climate has employed advanced instrumentation not only to reduce cost, but to provide additional capability. Like other tropical and sub-tropical regions, Florida's coastal environment is characterized by relatively infrequent but severe tropical storms. In many coastal engineering applications, the specification of the hurricane-associated storm surge and storm waves will be the major design criteria. The Florida CDN was created in order to provide field measurements of waves and tides year-around as well as during hurricanes. A measurement program of this nature must respond to both the immediate needs of practicing engineers as well as to research needs. Since it is unrealistic to hope for measurements of hurricane conditions at every location, the long term goal of research is to produce better models of storm waves and surge. Field measurements are required to assist in the formulation and validation of models. In the near term, actual measurements of both normal and severe waves and tides are the most reliable design input for the shallow and intermediate water depths.
LONGSHORE CURRENT FLOWS IN A WAVE BASIN
Authors: Visser P.J.
Published: June 2019

This paper describes the investigation into a method how to adjust the proper longshore current in a wave basin. In this method the basin geometry and the proper recirculation flow (outside wave guides) are determined by minimising the circulation flow (between wave' guides). Using one wave field and one uniform beach the length of the downstream wave guide wall, the distribution of the recirculation flow at the upstream wave guide wall and the recirculation flow were varied. The investigation shows that the adjustment of the longshore current has to be done carefully in order to get uniformity along the beach and the correct magnitude and distribution normal to the beach.
DYNAMIC CHARACTERISTICS IN THE NEARSHORE AREA
Authors: Horikawa Kiyoshi , Isobe Masahiko
Published: June 2019

A detailed discussion is made on the dynamic characteristics of waves and wave-induced currents in the nearshore area by using the laboratory and field investigation data collected during the last few years. The main purposes of this paper are to get the insight on the precise mechanism of the nearshore dynamic phenomena and to evaluate critically the applicability of the various assumptions commonly applied by the previous researchers.
MASS TRANSPORT IN PROGRESSIVE WAVES OF PERMANENT TYPE
Authors: Tsuchiya Toshito , Yasuda Takashi , Yamashita Takao
Published: June 2019

Mass transport phenomenon was first recognized by Stokes in 1847 using a Lagrangian description. Later, a basic theory for the mass transport in water waves in viscous fluid and of finite depth was derived by Longuet-Higgins in 1953. Theoretical solutions of mass transport in progressive waves of permanent type are subjected to the definitions of wave celerity in deriving the various finite amplitude wave theories. As it has been generally acknowledged that the Stokes wave theory can not yield a correct prediction of mass transport in the shallow depths, some new theories have been developed. Recently the authors(1974 § 1977) have derived a new finite amplitude wave theory in shallow water for quasi- Stokes and cnoidal waves by the so-called reductive perturbation method, in which the mass transport is formulated both in Lagrangian and Eulerian descriptions. On the experimental verification, Russell and 0sorio(1957) investigated and compared Longuet-Higgins' solution with experimental data of Lagrangian mass transport velocity obtained in a normal closed wave tank of finite length. Since then, many investigations, and nearly all of them, have employed the finite length of wave tank in carrying out their experiments. However, no experiment has yet been attempted at verifying the Stokes drift in progressive waves of permanent type in a wave tank of infinite length. It is not realistic nor economical in constructing such an infinitely long flume to investigate experimentally the mass transport velocity in progressive waves. Instead of using such an ideal wave tank, a new one incorporated with natural water re-circulation was equipped to carry out experiments by the authors(1978). It was confirmed from these experiments that mass transport in progressive waves of permanent type exists in the Same direction of wave propagation throughout the depth, and agrees with both the Stokes drift and the authors' new formulations, within the test range of experiments.