bluuebunny/crossref_metadata_2025 huggingface dataset:
ON THE PORTUGUESE WAVE REGIMEN
Authors: Barcelo Julio Patriarca
Published: June 2019

Some general characteristics of the wave regimen along the Portuguese coast and the zones next to it are presented. The paper is of a chiefly informative nature and results from the analysis of values obtained during an initial stage of swell observation, applied to studies carried out at the Laboratorio Nacional de En genharia Civil(LNEC),Lisbon. Presently, a network of observation posts is being installed on the Portuguese coast. These posts will be duly equipped and will make it possible to gather systematic observation as regards swell as well as to make a much more accurate analysis of the wave regimen and of the wave trains.
COMPUTATION OF LONGSHORE CURRENTS
Authors: Jonsson Ivar G. , Skovgaard Ove , Jacobsen Torben S.
Published: June 2019

The steady state profile of the longshore current induced by regular, obliquely incident, breaking waves, over a bottom with arbitrary parallel bottom contours, is predicted. A momentum approach is adopted. The wave parameters must be given at a depth outside the surf zone, where the current velocity is very small. The variation of the bottom roughness along the given bottom profile must be prescribed in advance. Depth refraction is included also in the calculation of wave set-down and set-up. Current refraction and rip-currents are excluded. The model includes two new expressions, one for the calculation of the turbulent lateral mixing, and one for the turbulent bottom friction. The term for the bottom friction is non-linear. Rapid convergent numerical algorithms are described for the solution of the governing equations. The predicted current profiles are compared with laboratory experiments and field measurements. For a plane sloping bottom, the influence of different eddy viscosities and constant values of bottom roughness is examined.
COMPARISON BETWEEN THE RESULTS OF LITTORAL-DRIFT COMPUTATIONS AND CUBATURE OF DEPOSITS IN A DREDGED CHANNEL
Authors: Motta V.F. , Bandeira J.V.
Published: June 2019

The total annual volume of littoral drift on either side of the mouth of Sergipe estuary, in the Northeast of Brazil, has been de_ termined by applying Caldwell's, Castanho's and Bijker's methods to the wave characteristics that had been recorded at a twenty-metre depth of water, over a whole year, for the design of an offshore oil terminal. The three computation methods yielded the same order of maj> nitude which was found to amount to about 80000Om^/year. The dominant drift is s outhwes tward, and its predicted amount is 660000m-*/year. It was also found that although the three methods lead to total re suits of the same order of magnitude, they do not agree as to the vari^ ation of littoral drift over the year for the s ame waves. An eight-metre deep shipping channe 1 has been dredgedaccross the bar. The channel was surveyed in December 1971, August and Decem ber 1972, and a cubature of the deposits was made after the littoraldrift computations had been carried out. As the latter had been per formed on a monthly basis, a comparison became possible between pre dieted and actual volumes of deposits for the same lengths of time. The predicted volumes for the whole year were found to be from 34 to 46% greater than the actual results. However, for the time interval August-December 1972 a remarkable agreement was found be^ tween predicted and actual results.
MEASURING SAND DISCHARGE NEAR THE SEA-BOTTOM
Authors: Wenzel Dieter
Published: June 2019

The direct and continuous measurement of the littoral drift is an essential problem with investigations on erosion of sandy coasts, as for instance at the island of Sylt. The measuring conditions require equipment of very particular features. Recent measurements have supplied informations about the conditions of sound propagation in sediment loaded water, leading to the conception of a sand discharge measuring device. It will consist in a combination of a current meter and a sand concentration meter. A convenient equipment is actually being developed. It is to supply an idea about the magnitude of the instantaneous sand discharge, the approximate remaining sediment transport vector, the phases of maximum and minimum sediment load, and so on. Consequently it will help to obtain a reliable statement about erosion processes, indispensable information for successful coastal engineering work.
MODE AND PERIOD OF SAND TRANSPORT IN THE SURF ZONE
Authors: Brenninkmeyer Benno M.
Published: June 2019

Three almometers-water opacity measuring devices-emplaced perpendicular to the beach, measure instantaneously and continuously the sediment concentration across the surf zone. Most of the variance of the sand movement is centered in frequencies of less than 0.25 Hz and between 1.15 and 1.25 Hz. Modes and frequency of sand transport differ within each of the dynamic zones of the surf. The motion of sediment in the inner and outer surf zones is small and virtually independent of the deep water wave periods. Outside the breaker zone, bed load movement is somewhat coincident with the prevailing swell period. Lighter concentrations move predominantly with a 0.8-0.9 second periodicity. In the breaker zone, sand moves along the bottom with frequencies equal to that of both the swell and sea, but most of the power is in lower frequencies. In the breaker zone sand is rarely thrown into suspension. In the transition zone, sediment motion is largely by suspension with a period a little longer than the swell.
WAVE STATISTICS ALONG THE NORTHERN COAST OF EGYPT
Authors: Manohar M. , Mobarek I.E. , Morcos A. , Rahal H.
Published: June 2019

As a forerunner of a comprehensive study of wave and energy climate of the Nile Delta coast covering a period of more than 50 years, wave measurements taken in 3 locations along the coast in the year 1972 were statistically analysed. Shortcut methods based on statistical approach were used to analyse the wave records enabling quicker analysis. Spectral analysis of the wave records indicates narrow spectral band similar to Raleigh distribution. The histograms and frequency distribution curves of significant wave heights, and the relationships between various statistical prarameters such as H , H,,,,,, H,,,, and H also max 1/10' 1/3 rms agree closely with Raleigh distribution curves and parameters enabling the use of Raleigh distribution function in subsequent studies. Finally since the wave characteristics and wave energy climates are most important in the analysis of coastline changes, they are drawn from the data obtained from the analysis.
WIND AND WAVE RELATIONSHIPS IN A SHALLOW WATER AREA
Authors: Driver J.S. , Pitt J.D.
Published: June 2019

An instrumentation system to record direct measures of both wind and wave conditions has been installed at the Wash. Data from these instruments are used in conjunction with long term wind records from another station to predict the frequency and duration of extreme conditions.
SCALE LAWS FOR BED FORMS IN LABORATORY WAVE MODELS
Authors: Mogridge G.R.
Published: June 2019

An experimental study of the variables governing the development of bed forms under wave action has been conducted. A wide range of conditions was covered by the use of a wave flume and an oscillating water tunnel. Scale laws for modelling bed forms are developed using the results of these experiments. It is recommended that the model sediment used should be the same density as in the prototype and its size should be scaled geometrically. If this is not practical, it is shown how the scale laws can be used to minimise the distortion of the bed forms produced in the model.
DELAY DISTANCE IN SUSPENDED SEDIMENT TRANSPORT
Authors: Hattori Masataro
Published: June 2019

In the previous paper (Hattori, 1969), a theory for the distribution of suspended sediment concentration due to standing waves was obtained on the basis of the concept of "delay distance" which accounted for the fluid-particle interaction and the inertia effect of sediment particles. The purpose of this paper is to make clear the physical dependence of delay distance to wave and sediment characteristics. The evaluation of delay distance from experimental results of distribution profiles of suspended sediment concentration is made by the assumption that the horizontal diffusion coefficient of suspended sediment is nearly equal to the vertical one.
NUMERICAL MODELLING OF SUSPENDED SEDIMENT
Authors: O'Connor Brian A. , Zein Samir
Published: June 2019

The present paper describes the application of a two-dimensional numerical suspended sediment model to problems having analytical solutions, as well as to laboratory and field situations. The model is based upon an implicit finite-difference solution to a two-* dimensional (longitudinal and vertical) diffusion-advection equation for suspended sediment transport. Horizontal eddy diffusion is neglected in comparison with vertical diffusion and vertical water motion is assumed negligible in comparison with the sediment fall velocity. The various applications indicate that the greatest errors in the model are due to large spatial concentration gradients and that errors can be controlled by a suitable choice of space and time step. In addition, it is considered that the model has great flexibility and seems to have an acceptable level of accuracy, at least in the field situations tested, provided the physical parameters of the model can also be determined accurately.
FACTORS CONTROLLING CHANGES TO AN OPEN COAST BEACH
Authors: Seelig William N. , Sorensen Robert M.
Published: June 2019

A study of historical information and field measurements in Sargent Beach, Texas, reveal that the shoreline is retreating with historic rates increasing from -10 feet per year in the late 1800's to -31 feet per year (-9.8 m/year) in the early 1970's. The cause of this erosion is the lack of an adequate sand supply to the beach zone. This sand deficiency is due to: a) reduced updrift sand input to the coast by the Brazos River beginning in 1945 and caused by decreased sediment transport capability of the river, b) increased sand storage in the Brazos Delta encouraged by jetties and vegetation, and c) possible offshore losses of sand due to hurricane wave energy focusing on the Brazos Delta in conjunction with river jetting during peak river flows.
WAVE GROUP FORMATION AMONG STORM WAVES
Authors: Rye H.
Published: June 2019

Wave data obtained m the North Sea for stormy weather conditions are analyzed to determine the extent of wave group formation among large waves; i.e. the number of large waves succeeding each other in one single run. Three periods associated with the passage of high sea states are examined. The average correlation between succeeding wave heights is found to be +0.2H, which indicates that wave heights do have a "memory". Wave group formations are found to be more pronounced when the sea is growing than decaying. The average lengths of wave runs are calculated.
OVERWASH PROCESSES ON ASSATEAGUE ISLAND
Authors: Fisher John S. , Leatherman Stephen P. , Perry Frederick C.
Published: June 2019

The primary barrier dune on the northern portion of Assateague Island, Maryland is presently being scarped on its seaward face and breached by storm-generated surges. During storms, sediment-ladened water moves across the dune line onto the barrier flats as overwash. The objective of this project is to determine the role overwash plays in barrier island sedimentary dynamics. An overwash model has been suggested. The nonvegetated overwash fan serves as a reservoir for the eventual distribution of the storm-deposited sand. Eolian processes, after the storm, determine the net contribution of overwash sand to each of the different morphological features, i.e., dunes, marsh, beach, etc.
ON THE DEPOSITIONS PROPERTIES OF ESTUARINE SEDIMENTS
Authors: Mehta Ashish J. , Partheniades Emmanuel
Published: June 2019

The depositional characteristics of floes of fine cohesive sediments in a turbulent flow field differ distinctly from those of a cohesionless material such as sand. This difference exists because the floe size and shear strength distributions depend on the sediment type as well as the flow condition itself; consequently, the problem of the depositional behavior of these floes is rather complex, and not easily amenable to analytic treatment. The present basic experimental study was carried out in a specially designed annular channel. The derived laws of deposition in relation to the time-rates as well as the steady-state concentrations are described and discussed. The reanalyzed results of other limited investigations agree well with the result of the study.
BEACH FILL PLANNING - BRUNSWICK COUNTY, NORTH CAROLINA
Authors: Vallianos Limberios
Published: June 2019

Planning has recently been completed for a shore protection project along a 9-mile (14.5 km) reach of shoreline fronting the Towns of Yaupon Beach and Long Beach in Brunswick County, North Carolina. The investigative program related to this planning effort embodied numerous interrelated elements which, on integration, resulted in a rational engineering design having a continuous beach fill as the central feature. Specifically, the investigation included: (a) definition of the environment, viz, wind, waves, storm tide frequencies, beach profile characteristics, shore processes, and ecological habitats along the proposed project area as well as in potential beach fill sources; (b) Designs and cost estimates including establishment of various fill profile configurations, cost optimization of fill positions, evaluation of the frequency of shoreline retreat and the attendant displacement of fill materials, evaluation of the compatability of materials from various fill sources with the natural beach materials, environmental impact studies, and economic studies; and (c) Final plan formulation arriving at the optimum fill plan in terms of engineering functionality, economics, and minimal adverse environmental impacts.
BEHAVIOR OF BEACH FILL AT ATLANTIC CITY, NEW JERSEY
Authors: Everts Craig H. , DeWall Allan E. , Czerniak Martin T.
Published: June 2019

A beach monitoring program between 1962 and 1972 at Atlantic City, New Jersey was designed to observe the response of beaches to waves and tides of specific intensity and duration as a first step in developing a storm warning system for low-lying coastal communities. As a by-product of that study the behavior of beach sand following two beach replenishment projects in 1963, and again in 1970, was determined. Monitoring was done using repetitive beach surveys above mean sea level (MSL) at seven profile lines. Survey results show that following replenishment, losses of the fill material above MSL were between nine and twelve times the losses measured in adjacent non-fill areas. Loss rates were largest at the updrift end of the fill region. About two and one-half times more material appeared to move in a seasonal on-offshore direction than moved permanently alongshore and above MSL to the southwest. For each meter of beach retreat, 5 to 6 m /lineal meter of fill were lost.
BEACH RESTORED BY ARTIFICIAL RENOURISHMENT
Authors: Newman Douglas Edward
Published: June 2019

This paper describes how a once popular pleasure beach became denuded by the abstraction of sand for industry and how, in more recent times, it was restored to its former levels. The history of the area has been studied in some detail, and it can be seen that the lowering of the beach caused progressive damage to the sea wall, eventually leading to flooding of some parts of the frontage. In the 1960's a parapet was added to certain sections of the sea wall, and local flooding was alleviated, but the lower parts of the wall and apron suffered continuously from wave attack and the situation deteriorated to an extent where complete reconstruction of the sea defenses had to be considered. It was shown that a scheme involving beach renourishment by the pumping of sand from offshore provided a more economical solution and the area now enjoys the amenities provided by the restored beach.
STABILITY CRITERIA FOR TIDAL BASINS
Authors: Renger Eberhard , Partenscky Hans-Werner
Published: June 2019

The contribution deals with the morphologic examinations and calculations for a deep-water harbour which is to be constructed in the tidal flats of the Elbe estuary near the North Sea islands of Scharhorn and Neuwerk. An attempt is made to examine the stability of tidal channels (gullies)and tidal flats which may be disturbed to a greater or lesser extent by the various proposals for the connecting dike between the industrial area near the harbour and the coastline. The underlying logic for the determination of the equilibrium of the flats and the quantitative solution for the sand-balance is as follows: It has been shown in several empirical investigations that the increase of the relative volume of the tidal basin (V/VM ), referenced to the gully volume for MLW, can be determined as a simple function to the base (a)logarithm of the geodetic elevation (z*) between MLW and any higher contour level up to MHW. Furthermore it can be shown that (VMT ) is also a function of the tidal drainage area (E). The base(a)has been related to the size of the tidal drainage area (E), because this area is subject to considerable modification by offshore structures such as dikes and causeways.
IRREGULAR WAVE ATTACK ON A DOLOS BREAKWATER
Authors: Morais C. Campos
Published: June 2019

The paper deals with two-dimensional tests on a scale model of a dolos breakwater. It is related with the construction of a large harbour at Sines for tankers with up to 1 million dwt, ore ships with up to 300,000 dwt, general cargo, etc. The main breakwater is design ed with 40 t dolos, in order to withstand waves with up to 1 1 m significant wave height(100 years return period). Considerations on wave data and on modelling the spectrum ( Pierson-Moskowitz ) precede the presentation of three sets of tests on LNEC's irregular wave flume. Main results are compared with those from regular wave tests. The most important conclusions are stressed: influence of pla_ cement on dolos damages, irrelevance of maintenance, importance of the singular zone of the dolos support base, disadjustment of Hudson's formula for calculation of dolos weight using H as significant wave height,and importance of individual movements for the risk of breaking of individual blocks.
Complete Proceedings - Single PDF Download
Authors: O'Brien Morrough P.
Published: June 2019

These International Conferences on Coastal Engineering have grown over the years since 1950 in attendance, in the number of papers presented, and in scope of engineering and scientific content There has been an even greater increase in the work of arranging for a conference-a task which, if well done, gives the erroneous impression of requiring little effort The physical arrangements and the social events of this conference have been superbly done and the Coastal Engineering Research Council and the other sponsoring organizations are most grateful to Chairman S^rensen, Professor Lundgren and the Copenhagen Organizing Committee.
REVISIONS IN WAVE DATA PRESENTATION
Authors: Draper Laurence
Published: June 2019

In 1966 the author proposed, at the Tenth Conference on Coastal Engineering, methods (Reference 1) of presentation of wave data which were thought likely to be useful to the engineering user. Data obtained from many recording stations have been processed and presented in the formats proposed, and appear to have been able to provide answers to many of the wave questions posed by engineers. However, from time to time additional questions arise, and improvements in technology enable answers to more sophisticated questions to be given. The purpose of this paper is to describe the additions thought necessary to cope with these changes; there are no alterations to the 1966 presentation methods, only additions.
RESULTS OF RIVER MOUTH TRAINING ON THE CLARENCE BAR, NEW SOUTH WALES, AUSTRALIA
Authors: Floyd Cyril D. , Druery Bruce M.
Published: June 2019

A case study is given of river training works at the mouth of the Clarence River. The study spans a period of ninety years. Extensive hydrographic data from the later part of this period is presented and examined in detail. Prior to 1903 internal training walls had been constructed to stabilise the internal channel and stabilise the bar location at the mouth of the Clarence River. In 1956 construction started on entrance jetties with the aim of deepening the bar. The work was carried out over a period of 16 years. The slow rate of construction has allowed changes in bar depth to be compared with depths estimated by an empirical formula which relates bar depth to tidal flow and channel width. Results have shown that the empirical formula gives a reasonable estimate of bar depths and that bar depth is independent of jetty length. Results have shown that the behaviour of the bar is strongly affected by floods. Some details of bar volume and movement are presented.
SEDIMENTATION PROBLEMS AT OFFSHORE DREDGED CHANNELS
Authors: Kadib A.A.
Published: June 2019

Estimating the rate of sediment deposition and annual maintenance dredging at offshore dredged channels have been two of the most challenging tasks confronting coastal engineers in the past 10 to 15 years. Because of the complexity of the mechanism of sediment-flow interaction and the lack of available practical methods for estimating the sediment transport rate under waves and current action, it is felt that a simple and rational method is needed for describing sediment behavior at offshore dredged channels and estimating accretion rates. It is hoped that this paper contributes to the answer of this problem. The paper describes the mechanism of sediment deposition and presents a simple method for estimating the rate of annual maintenance dredging. The effect of using a submerged breakwater for relieving the sedimentation problem within the dredged channel is also presented.
CHANGES DUE TO JETTIES AT TILLAMOOK BAY, OREGON
Authors: Komar Paul D. , Terich Thomas A.
Published: June 2019

Bayocean Spit, separating Tillamook Bay from the Pacific Ocean on the north Oregon coast, underwent severe erosion following construction of a north jetty at the bay entrance in 1914-17. This erosion ultimately led to the complete breaching of the spit in 1952. Simultaneous to the spit erosion south of the entrance, the shoreline north of the north jetty advanced seaward by some 600 m (2000 ft). This pattern of erosion and deposition following jetty construction has generally been interpreted as the jetty blocking a large north to south net littoral drift in the area, estimated by a previous study at 620,000 m3/yr (800,000 yd3/yr). Our reexamination of the shoreline changes and patterns of erosion and deposition following jetty construction disagrees with this interpretation, and instead we conclude that all of the changes resulted from local rearrangements of the beach due to the disrupted equilibrium following jetty construction, but at the same time maintaining an overall condition of zero net littoral drift. This interpretation is supported by other evidence that indicates a near-zero net drift on this portion of the Oregon coast. Thus severe coastal erosion can result from jetty construction even in areas of zero net littoral drift. A new south jetty has been recently completed (1974). The result has been further realignments of the shoreline with accretion and shore-: line advance immediately south of the south jetty. This provides further confirmation that a zero net littoral drift exists in the area. This study also demonstrates the effects of building only a single jetty rather than a pair of jetties. Following construction of the north jetty, the outer bar or ebb-tide delta at the Tillamook Bay inlet grew appreciably in size.
IMPACT OF YACHTING MARINAS ON BEACHES
Authors: Lepetit J.P.
Published: June 2019

The development of tourism resulted in the construction of very many small yachting harbours along the French Mediterranean shore during recent years. Some of them were constructed on the rocky foreland located at the end of sandy beaches. Such beaches being a priori stable, no particular sedimentation investigation was carried out. In several cases, the construction of a port led to rapid evolution of the beach, accretion occurring in the vicinity of the port and erosion elsewhere.
HARBOUR INLETS ON TIDAL ESTUARIES
Authors: Vollmers Hans
Published: June 2019

Two important points should be considered, if a harbour mouth is planned, on a river: 1. The traffic conditions especially the navigation must be considered (i.e. large width of the mouth) 2. The sedimentation should, be small (i.e. small width of the mouth) These conditions are contradictory. Harbour mouths are lateral enlargements. The current doesn't follow these enlargements, a separation sheet forms which is characterized by eddies. A more or less great mass of water is in movement in the enlargement. These rotating movements are called "vortices". One distinguishes "primary vortices", "secondary vortices" etc. depending on the initiating current (Fig. 1).
PARAMETRIC REPRESENTATION OF A WIND-WAVE FIELD
Authors: Rye Henrik , Svee Roald
Published: June 2019

The applicability of various spectral shape parameters is discussed. The wave .height distribution from 60 actual wave recordings is computed and compared to the Rayleigh distribution. The behaviour of various wave period parameters is discussed. Based on results from field data as well as numerical computations, it is concluded that some of the spectral wave parameters frequently used today may not be suitable for characterizing the wave field.
INLET CHANGES OF THE EASTFRISIAN ISLANDS
Authors: Luck Gunter
Published: June 2019

The seven sandy islands of the Eastfrisian group would appear to be initially formed and now continually supplied with sand from the Westfrisian group and the mainland to the west. The inlets between these islands are in dynamic equilibrium with the strong tidal currents of the near 2,5 m range in the area. Hydrographic information dating back to 1650 permits the development of a hypothetical model which explains the historic changes and might predict future trends. The installation of coastal defense structures on the eroding western extremities of some islands in the mid 19th century has greatly influenced the bars by which sand is transported from island to island in an easterly direction.
TRACING ESTUARINE SEDIMENTS BY NEUTRON ACTIVATION
Authors: Ecker Richard M. , Sustar John F. , Harvey William T.
Published: June 2019

Tracing the movement of dredged sediments in north San Francisco Bay was accomplished jointly by the San Francisco District of the U.S. Army Corps of Engineers, Explosive Excavation Research Laboratory (now the Explosive Effects Division of the Weapon Effects Laboratory, U.S. Army Waterways Experiment Station), and the Stanford Research Institute. The study involved developing a technique which would permit the longterm tracing of fine sediments dredged from Mare Island Strait after disposal at the Carquinez Strait disposal site; application of the tracer; disposal of the tagged sediment for the February-March 1974 dredging of Mare Island Strait; sampling bottom sediments throughout the study area for a 10-month period; and, quantitative analysis of the collected samples.
MEASUREMENT OF SUSPENDED SEDIMENT IN THE SURF ZONE
Authors: Kilner F.A.
Published: June 2019

The sea is an important source of water for cooling and other industrial purposes. From practical considerations, the water is usually drawn from a zone close to the shore, perhaps within one or two kilometres of the shore line through an intake structure such as a tunnel, pipeline or harbour or some comhination of these. If the coast is exposed to strong ware action and the local sea bed is of a sandynature, sediment will he lifted into suspension "by the oscillatory motion induced by the waves, and thus any sea water transported to the shore will contain a sediment load. This sediment content may have an adverse effect on the operation of the intake structure in various ways. If the water velocity is maintained at a high enough value throughout to avoid deposition, then the sand water mixture will tend to abrade the surface with which it is in contact. If however the water velocity is permitted to fall below the deposition value, sediment accumulation will occur which may be intentional as in a settling basin (requiring regular dredging or other removal) or inadvertent as in a pipe conduit (leading to partial blockage of the pipe). The writer has been associated with two sea water intake schemes, one on the western coast of South Africa, being a cooling water supply for a nuclear power station with a water consumption of about 100 m3/s; the other an intake for the recovery plant of a mining company in Namibia, water capacity about 1 m3/s. In both cases, information was needed concerning the variation of sediment concentration with distance above the sea bed, this distribution being measured at selected distances from the shore line. This led to a review of available techniques for determining the sediment content of sea water, and thence to development of new procedures and instruments. The details of these developments are presented in this paper.
HURRICANE WIND AND WAVE FORECASTING TECHNIQUES
Authors: Bretschneider Charles L. , Tamaye Elaine E.
Published: June 2019

Measurements needed to calibrate both significant wave and wave spectrum methods. These concern extreme waves hence related more to design than operations.

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FACTORS INFLUENCING ESTUARY SEDIMENT DISTRIBUTION
Authors: Kendrick Mary P. , Derbyshire B.V.
Published: June 2019

Many factors combine to determine the way in which sediments are distributed throughout an estuary. Most fundamental are those which produce the natural rhythm of diurnal (or semi-diurnal), bi-monthly and seasonal fluctuations due to predictable variations in tide and weather. This group includes tidal discharge, fresh river flow and the resultant distribution of saline water. When considered together with such factors as the availability and properties of sediments within and beyond the landward and seaward limits of an estuary, they determine how the available material shall be eroded, transported and deposited during the course of the natural cycle. Superimposed on these regular fluctuations are the effects of other factors which may or may not be predictable, are not necessarily regular in occurrence and may be either natural or man-made. These include secular trends, such as long-term adjustments in land/sea levels or climatic conditions, which have a small but continuing effect on some of the factors in the first group. They also include sudden, short-term events like earthquakes or hurricanes which impose a shock to the system that may involve the movement of large quantities of material during the subsequent period of readjustment.
GENERATION OF TROUGHS BY DENSITY CURRENTS
Authors: Speekenbrink Hans
Published: June 2019

Along the northern bank of the so-called "Maasgeul" scour has occurred, causing a trough. It is concluded from field measurements that the trough development is induced by density currents along the slope of the bank. The stratified flow system is dealt with mathematically. The calculated results are compared with the field measurements and agree fairly well. Trough development can be avoided by flattening the slope or by a bottom protection.
CONCEPT OF MINIMUM SPECIFIC ENERGY AND ITS RELATION TO NATURAL FORMS
Authors: McKay Gordon R. , Kazemipour Ahad K.
Published: June 2019

It is proposed to show in this paper that there is a solution to the problem of non-uniform flow and this solution not only explains in detail many land forms which occur naturally, but thereby, yields a definition of 'form' loss. If a channel, in which the transverse distribution of specific energy is uniform, converges and/or diverges, and the bed changes so that the flow will be critical at all cross-sections at the same time, the channel appears to be close to being hydraulically smooth. Many natural forms, particularly estuaries, are readily explicable in this way. The most obvious one is the bar at the mouth of a river. It follows, if the river enters the sea with reasonable uniform grade, which most rivers do, the bed must rise as the flow loses the restricting influence of the banks (i.e. the width increases) if constant specific energy is to be maintained. It is possible to calculate with considerable accuracy the dimensions of useful structures based on this concept. A large number of full size but nevertheless experimental structures have been built making use of the resultant benefits which develop:- low turbulence, accurate differential water levels and a clearly defined flow pattern, allowing very considerable savings to be made by eliminating expensive protective works.
TSUNAMI HAZARD AND DESIGN OF COASTAL STRUCTURES
Authors: Pararas-Carayannis George
Published: June 2019

Damage of coastal structures by tsunamis results by the direct and indirect action of hydrostatic and dynamic pressures, foundation failures, overtopping and flooding. Reliable assessment of the potential tsunami hazard at a coastal site and adequate engineering design of critical structures require analysis and understanding of all aspects of a tsunami system leading to its terminal behavior. Description of the space-time history of tsunami waves generated by impulsive disturbances require consideration of events and processes in the following regimes: (a) generation; (b) propagation and dispersion; and (c) termination. Processes and events in each regime during the development of a tsunami are under their own unique hydrodynamic constraints but are dependent on what has preceeded. In predicting tsunami wave characteristics at some distance from the generating source, the error structure may be pyramidal. Essential to any method of tsunami prediction at a distant or a nearby coast will be the full consideration and study of tsunami generative mechanisms. If the tsunami generation mechanics cannot be deduced with a reasonable degree of accuracy, it is not likely that the tsunami terminal aspects will be reliably predicted. Prediction of tsunami height at a distant or at a nearby coast requires knowledge of the magnitude and type of ground displacements in the tsunami generating area and of the characteristics of the surface waves resulting from such action. Although all mechanisms involved during tsunami generation are not fully understood, it is possible to obtain a suitable tsunami initiating function through the use of experimental data, historical data, and established empirical relationships, for each type of generating mechanism. Reliable computation of the tsunami propagation effects over and across the ocean can be obtained with proper modeling to provide an adequate description of the tsunami energy flow through the use of physical and numerical studies. Similarly, the terminal aspects and nearshore modification of the tsunami wave system can be approximated to provide the engineering criteria necessary for the assessment of the potential tsunami hazard at a coastal site.
NUMERICAL CALCULATION OF WAVE FORCES ON STRUCTURES
Authors: Nichols B.D. , Hirt C.W.
Published: June 2019

A finite-difference technique for solving the Navier-Stokes equations for an incompressible fluid is used to calculate transient wave forces experienced by fixed and moving bodies. The numerical technique is based on the Marker-and-Cell (MAC) method developed by Harlow and Welch (1965). This new technique uses an especially simple solution algorithm that is designed for persons with little or no experience in numerical fluid dynamics. Originally conceived as an instructional tool, it has proven to be an extremely useful and versatile calculational method. Many useful calculations are possible with the publicly available code, SOLA-SURF, which is briefly described in Sec. II; however, the outstanding feature of this numerical scheme is the ease with which it can be modified to handle more complex problems. Reported here, in Sec. Ill, are examples to illustrate the utility of this new calculational tool for investigating the dynamic interactions between ocean waves and coastal structures.
WAVE FORCES ON SQUARE CAISSONS
Authors: Mogridge G.R. , Jamieson W.W.
Published: June 2019

The forces and overturning moments exerted by waves on large vertical square-section caissons have been measured in the laboratory. Each model caisson extended from the bottom of a wave flume through the water surface and was oriented either with one side perpendicular to the direction of wave propagation or turned through an angle of forty-five degrees to this position. For a given orientation, each model was tested for a range of wave heights (up to the point of breaking) for various wave periods and water depths. A digital computer was used for the acquisition, processing, plotting and storage of the experimental data. In addition to the experimental work, an approximate theoretical method is presented which allows the wave loadings on a square caisson to be estimated by means of a simple desk calculation. The experimental data shows that this simple method of calculation is reasonably accurate over a wide range of wave conditions and caisson sizes.
WAVE PRESSURES ON LARGE CIRCULAR CYLINDRICAL STRUCTURE
Authors: Nakamura Hiroshi
Published: June 2019

The field observations on wave pressures on large circular cylindrical structures are performed at the cooling water intake structure for Hamaoka nuclear power plant, which is located at the coast of Pacific Ocean. In this report, the results of the field observation on wave pressures are compared with the results of the calculation by small amplitude wave theory considering wave diffraction around the cylinder.
FORCES ON ROUGH-WALLED CIRCULAR CYLINDERS
Authors: Sarpkaya Turgut
Published: June 2019

This paper presents the results of an extensive experimental investigation of the in-line and transverse forces acting on sand-roughened circular cylinders placed in oscillatory flow at Reynolds numbers up to 1,500,000, Keulegan-Carpenter numbers up to 100, and relative roughnesses from 1/800 to 1/50. The drag and inertia coefficients have been determined through the use of the Fourier analysis and the least squares method. The transverse force (lift) has been analysed in terms of its maximum and root-mean-square values. In addition, the frequency of vortex shedding and the Strouhal number have been determined. The results have shown that all of the coefficients cited above are functions of the Reynolds number, Keulegan-Carpenter number, and the relative roughness height. The results have also shown that the effect of roughness is quite profound and that the drag coefficients obtained from tests in steady flow are not applicable to harmonic flows even when the loading is predominantly drag.
FLOW SEPARATION, WAKE VORTICES AND PRESSURE DISTRIBUTION AROUND A CIRCULAR CYLINDER UNDER OSCILLATORY WAVES
Authors: Iwagaki Yuichi , Ishida Hajime
Published: June 2019

Flow separation of a laminar boundary layer on the surface of a circular cylinder developed by monochromatic waves has been investigated both theoretically and experimentally, and next, characteristics of vortex formation and shedding have been discussed with Keulegan-Carpenter's number and Reynolds number, and finally, local depressions of the wave pressure around the cylinder induced by wake vortices have been examined in the experiment .
APPLICATION OF FETCH AREA METHOD IN MONSOON WAVE HINDCASTING
Authors: Liang Nai-Kuang , Tang Shih-Tsan , Lee Ben-Juen
Published: June 2019

The Fetch Area Method ( FAM ) derived from Elementary Wave Model is used to analyze the winter monsoon wave of Taichung Harbour. The empirical wind-wave energy transfer coefficient f determined by FAM for this area is 7.25 x 10~ A relationship between g T , /2TTU and g t'/u is also found, where U is the average wind speed and t* the duration. A comparision of the wave hindcasting of FAM has shown that the latter is better than the former, and the former is valid only as the wind velocity increases, once the wind decreases the SMB Method is no more valid.
FORCES ON A SPHERE UNDER LINEAR PROGRESSIVE WAVES
Authors: Jenkins Scott A. , Inman Douglas L.
Published: June 2019

The rms horizontal forces which result from the action of a linear, deep and intermediate water, laboratory scale waves were measured on submerged spheres removed several diameters from the free surface. The study focuses on unseparated flows encountered at small values of (d0/D), where d0 is the orbital diameter and D is the sphere diameter. Under these conditions, a steady streaming around the vertical equator of the sphere was observed, giving rise to a circulation in the sense of rotation of the orbital motion. This phenomena was found to diminish the resultant of the wave pressure on the sphere predicted by potential theory. In approaching the onset of separation, the drag coefficients were found to compare in size with those reported for similar motions in steady unidirectional flow.
DESIGN OF MAIN BREAKWATER AT SINES HARBOUR
Authors: Mettam John Dorrington
Published: June 2019

In March 1972 the author's firm in association with two Portuguese firms of consulting engineers, Consulmar and Lusotecna, were appointed by the Portuguese Government agency Gabinete da Area de Sines to prepare designs for the construction of a new harbour at Sines on the west coast of Portugal. The location is shown in Figure 1. The main breakwater, which is the subject of this paper, is probably the largest breakwater yet built, being 2 km long and in depths of water of up to 50 m. It is exposed to the North Atlantic and has been designed for a significant wave height of 11 m. Dolos units invented by Merrifield (ref. 1) form the main armour. The project programme required that studies be first made of a wide range of alternative layouts for the harbour. After the client had decided on the layout to be adopted, documents were to be prepared to enable tenders for construction to be invited in January 1973. This allowed little time for the design to be developed and only one series of flume tests, using regular waves, was completed during this period. Further tests in the regular flume were completed during the tender period and a thorough programme of testing with irregular waves was commenced later in the year, continuing until August 1974 when the root of the breakwater was complete and the construction of the main cross-section was about to start. The model tests, which were carried out at the Laboratorio Nacional de Engenharia Civil in Lisbon, were reported by Morals in a paper presented to the 14th International Coastal Engineering Conference in 1974. (ref. 2)
DESIGN AND CONSTRUCTION OP PROTECTIVE STRUCTURE FOR NEW REEF RUNWAY HONOLULU INTERNATIONAL AIRPORT
Authors: Darling Wilfred D.
Published: June 2019

This paper describes the design and construction of the protective structure for a new Reef Runway at the Honolulu International Airport with special emphasis on the use of dolosse concrete armor units.
PERMEABLE SEAWALL WITH RESERVOIR AND THE USE OF "WAROCK"
Authors: Ijima Takeshi , Tanaka Enzoh , Okuzono Hideaki
Published: June 2019

Interesting facts that a uniformly permeable seawall of vertical faces with appropriate reservoir has remarkable characteristics of absorbing wave energy even for long period waves in the same degree of usual sloped-face seawall and that these characteristics appear most clearly for permeable seawall of trapezoidal cross-section with backward-sloped reservoir wall are found theoretically and experimentally. Moreover, it is shown that a perforated wall with reservoir has similar characteristics to those for uniformly permeable wall with reservoir. "Warock" is a type of concrete blocks which was invented in order to realize the wave absorbing seawall in practical works. Several examples of ever constructed wave absorbing seawalls, quaywalls and breakwaters by means of "Warock" in Japan are introduced.
QUAY WALL WITH WAVE ABSORBER "IGLOO"
Authors: Shiraishi Naofumi , Palmer Robert Q. , Okamoto Hiroshi
Published: June 2019

This report summarizes the results of the research on a gravity type quay wall comprising several layers of concrete blocks with a special shape called "Igloo" as shown in Photograph- 1.
OVERTOPPING OF RUBBLE-MOUND BREAKWATERS BY IRREGULAR WAVES
Authors: Ouellet Yvon , Eubanks Pierre
Published: June 2019

This paper describes the results of an experimental study on the effect of waves on rubble-mound breakwaters, wave transmission subsequent to wave overtopping, the stability of the three sides subjected to wave action and the effect of the breakwaters on waves. Two different rubble-mound breakwaters were tested, i. e. one with a rigid impermeable crest and the other with a flexible permeable crest. Tests were performed with both regular and irregular wave train systems. To obtain the simulated irregular wave trains, four theoretical spectra were chosen: Neumann, Bretschneider, Moskowitz, and Scott. Results obtained from tests with irregular wave trains were compared to those obtained from tests with regular wave trains. It was found that more information was obtained on the behaviour of the structure when it was submitted to the attack of irregular waves than when submitted to regular waves, and that the use of irregular wave trains gave more interesting results.
ADDED MASSES OF LARGE TANKERS BERTHING TO DOLPHINS
Authors: Hayashi Taizo , Shirai Masujiro
Published: June 2019

The added masses of large tankers berthing to dolphins are studied both theoretically and experimentally. The movements of large vessels in shallow water in the directions normal to their planes of symmetry cause counterflows of appreciable velocities under the hulls. The inertia of these counter-flows is shown to have an important effect on the added masses of the vessels. A theoretical formula is derived to determine the mass factor of an ocean vessel in shallow water as a function of the ratio Draught/Water- depth, the Froude number of the vessel and the coefficient of head loss of the counter-flow under the hull. Experiment is made to determine the mass factor. Comparison:, between the theory and the experiment shows a good agreement.
SUBHARMONIC COMPONENTS IN HAWSER AND FENDER FORCES
Authors: Van Oorschot J.H.
Published: June 2019

Forces in mooring lines and fenders of a moored vessel exposed to waves have a mixed harmonic and a subharmonic character. The subharmonic oscillations, with periods well beyond the range of wave periods, may cause forces that are as large as, or even larger than the forces associated with the harmonic oscillations. The origins of the subharmonic oscillations are discussed and it is shown that in model testing, the correct reproduction of both the mooring arrangement and the irregular wave motion is essential. The subharmonic motions, and consequently the total forces, can be partially reduced by specially adapted mooring arrangements as tests on various mooring systems have shown.
LOW-COST SHORELINE PROTECTION
Authors: Edge Billy L. , Housley John G. , Watts George M.
Published: June 2019

As the public interest in low-cost, self-installed solutions to shoreline erosion continues to grow, the involvement of private enterprise in developing solutions intensifies. Now that low-cost devices are identified as a salable commodity as goods or services, the number of inventors, creative engineers, agronomists, and foresighted planners producing potential designs are rapidly growing. Over two hundred devices, both proven and untested devices, have been cataloged as a part of the National Shoreline Erosion Demonstration Program. This program calls for the Corps of Engineers to plan, establish, and conduct for a period of five years a shoreline erosion control development and demonstration program including physical and vegetative devices.
DESIGN PROCEDURES FOR OCEAN OUTFALLS
Authors: Layton Jeffrey A.
Published: June 2019

This paper discusses procedures for designing ocean outfalls and offers the coastal engineer a practical design guide outlining the necessary steps required to plan, design, and construct an outfall. The design steps reviewed in this paper include site location considerations, environmental studies, outfall and diffuser hydraulics, pipe materials selection, pipe support systems design, and construction techniques.