bluuebunny/crossref_metadata_2025 huggingface dataset:
DETAILED DESIGN OF A WAVE ENERGY CONVERSION PLANT
Authors: Retief G. de F. , Muller F.P.J. , Prestedge G.K. , Geustyn L.C. , Swart D.H.
Published: June 2019

A preliminary assessment of wave energy conversion by means of the Stellenbosch Wave Energy Converter (SWEC) has indicated the viability of this system as a supplementary source of electric power. In order to refine the preliminary estimates of the cost of power delivered, detailed design of a 770 MW (rated output) installation at a site 60 km north of Cape Town has been undertaken. This paper describes the power conversion characteristics of the SWEC at the proposed site, structural design of the collector arms and generating tower for both mass gravity or piled solutions, a construction scenario involving a casting harbour in nearby Saldanha Bay and the towing and placement of 53 m long precast modules, and finally an assessment of the environmental impact of the proposed 40 km array on the adjacent coastline. The proposed system is found to be both technically and economically feasible and offers a useful contribution towards future electric power supply.
FULL-SCALE WAVE FORCES ON PILES IN SHALLOW WATER
Authors: Sparboom Uwe , Efthimiou Nico , Voigt Andreas
Published: June 2019

This paper presents some results of simultaneous full-scale wave kinematic and local force measurements (field and laboratory) on a slender, vertical cylindrical pile (test-section) under shallow water conditions. The usual application of Morison's equation is taken under critical consideration due to the real flow regime near the surf zone. The data were analyzed in the time domain as well as in the amplitude and frequency domain. Two estimation methods for force coefficients were tested and compared.
DYNAMIC ANALYSIS OF PILE STRUCTURES TO PERIODIC WAVES
Authors: Ishida Hajime , Konda Yoshinori
Published: June 2019

This paper has dealt with the dynamic response of offshore structures to the ocean waves. In order to establish the calculation scheme for offshore structures, the methods of transfer matrices and of structural-property matrices have been introduced and applied to the analysis of dynamic response of pile structures. The validity of these calculation methods have been verified by the experiments in the laboratory.
EVOLUTION OF INTERFACIAL WAVES ALONG AN UNSTEADY SALT WEDGE
Authors: Nakano Wataru , Yakuwa Isao
Published: June 2019

Field measurements of the receding salt wedge were made at the mouth of the Ishikari River in October 1981. The gradually growing interfacial waves and the diffusion pattern of salinity are visualized by the Ultrasonic Method. The evolution mechanisms of waves are analysed in detail by calculating the power spectra of wave records. It is pointed out that the wave breaking, the wave-eddy interaction and the nonlinearity of waves are factors dominating the evolution. The nonlinear property of interfacial waves is studied further by watertank experiments.
BREAKING WAVE DESIGN CRITERIA
Authors: Thornton E.B. , Wu C.S. , Guza R.T.
Published: June 2019

Breaking wave heights measured in both field and random wave laboratory experiments are examined. The dependence of breaker height and breaker depth on beach slope and deep water steepness is presented. The results are compared with the design curves of the Shore Protection Manual (SPM) and the predictions of the randan wave model by Goda (1975). The comparisons indicate that the significant breaker height, based on Goda's model, is slightly conservative for the experimental cases; but the maximum breaker heights are reasonably predicted by the model. The design procedures in the SPM are based on a monochromatic wave breaking, and appear overly conservative, particularly for low wave steepness (less than 0.01) which occur frequently on the West Coast of the United States. The use of the Rayleigh distribution to predict wave height statistics is tested with random wave data for both deep and shallow water regions.
SEDIMENTATION PROCESSES ALONG THE EAST FRIESIAN ISLANDS, WEST GERMANY
Authors: FitzGerald Duncan M. , Penland Shea , Nummedal Dag
Published: June 2019

The East Friesian Islands are located on a high energy shoreline. The average deepwater significant wave height exceeds 1.0 m and the spring tidal range varies from 2.7 to 2.9 m. A large easterly net longshore transport rate has caused eastward growth of the barrier islands. Reclamation of tidal flats has significantly reduced the backbarrier area and has resulted in a decrease in the ratio of inlet width to barrier island length from 42% to 16% during the past 300 years. The headwaters of the major channel dissecting the tidal flats erode in an eastward direction in response to tidal and wave driven currents, wave suspension, and eastward barrier island elongation. Consequently, the drainage systems of most of the inlets are highly asymmetric with 70-80% of the tidal prism coming from the east. This pattern results in a hooked main channel. The location of the channel at the inlet throat is controlled by the westward ebb flow in the main channel, the inertia of ebb flow in the tributary creeks, eastward longshore sediment transport, and the regional stratigraphy. The position and orientation of the main ebb channel controls the symmetry of the ebb-tidal delta about the inlet shoreline. This, in turn, affects the location of swash bar attachment to the beach and overall trends of erosion and deposition along the downdrift barrier.
MATHEMATICAL MODELLING OF WATER-QUALITY FOR LONG TIME PERIODS
Authors: Huizinga P.
Published: June 2019

This paper presents a one-dimensional dynamic water-quality model suitable for long-term application to estuaries. The computation techniques used in the model are very simple, but very good results have been obtained both for theoretical test cases and from applications to estuaries when compared with prototype measurements.
SURGES AND WAVES GENERATED BY SHIPS IN A CONSTRICTED CHANNEL
Authors: Herbich John B. , Schiller Robert E.
Published: June 2019

A study of surges and waves was initiated because of serious bank erosion along the Sabine-Neches Waterway, located in East Texas. The Waterway provides ship access from the Gulf of Mexico to Port Arthur and Beaumont. The design water depth in the ship channel is 12.12 m (40 ft). The 1978 tonnage of ships using the waterway was 69,740,900 tons (1). The highway on the east bank of the Waterway between Port Arthur and Mesquite Pt. leading to Louisiana had to be relocated several times because of bank erosion. The erosion was thought to be principally caused by ship traffic generating surges and waves. The main purpose of the study was to: 1. evaluate the magnitude of surges and waves generated by ships using the Waterway, 2. evaluate bank erosion potential, and 3. evaluate and recommend the most economical structural measures to prevent further bank erosion. The results of this first part of the study are reported in this paper.
THE EFFECT OF WAVE DIRECTION ON SHIP MOTIONS IN A HARBOUR ENTRANCE CHANNEL - MODEL STUDY APPROACH
Authors: Van Wyk A.C. , Zwamborn J.A.
Published: June 2019

Basic knowledge of a ship's vertical motions in waves of different angles of approach is an essential requirement in the formulation of allowance criteria on which to base harbour accessibility under extreme wave conditions. A comprehensive series of scale model tests are being undertaken to establish minimum underkeel clearance for given channel depths and sea states using two models representing typical 150 000 and 270 000 dwt bulk carriers.
SHIP WAVES IN SHALLOW WATER AND THEIR EFFECTS ON MOORED SMALL VESSEL
Authors: Kurata Katsuhiko , Oda Kazuki
Published: June 2019

The characteristics of ship-generated waves in shallow water and the motions of moored small vessel induced by the ship waves were investigated in a wide range of water-depth and ship-length Froude Numbers. The maximum heights and periods of ship waves were obtained as functions of Froude Number. The relationships between maximum angular and translatory displacements of moored vessel and the maximum ship waves were determined.
SHALLOW WATER WAVES: A SPECTRAL APPROACH
Authors: Vincent Charles L.
Published: June 2019

Bouws et al. (1983, 1984) have shown that wind sea spectra in finite depth water can be described by a self-similar spectral equation that in the deep water limit is the JONSWAP spectrum (Hasselmann et al. 1973). This paper shows that the spectral parameter a is linked to wave steepness, for wind sea and swell; presents a simple model for wave transformation across the surf zone; and shows that the spectral theory provides data similar to the results of Bretschneider (1958) for shallow water wave growth.
REYNOLDS STRESS IN SURF ZONE
Authors: Sakai T. , Sandanbata I. , Uchida M.
Published: June 2019

The on-offshore and the vertical components u, w of the velocity in a surf zone on a uniformly sloping beach in a wave tank were measured simultaneously with a laser-doppler velocimeter under two conditions. The time variation of the Reynolds stress -u'w' during one wave period is discussed. The Reynolds stress behaves as that in the oscillatory pipe flow does. The magnitude of the terms including the Reynolds stress terms in the on-offshore momentum equation is estimated. The Reynolds stress terms does not play any important role in the on-offshore momentum transfer during one wave period in the surf zone.
A DYNAMICAL EXPRESSION OF WAVES IN SHALLOW WATER
Authors: Tsuchiya Y. , Yasuda T.
Published: June 2019

Making the assumptions that solitons are one of the most elementary excitation in random nonlinear waves in shallow water and that the waves have a coherent dynamic structure of solitons, we attempt to describe the swell-like waves theoretically "by deriving the asymptotic multisoliton solution for the KdV equation. Formulations of the random wave profiles and internal properties are also made. We conclude from the comparisons between observed and theoretical results of the propagation characteristics of the swell-like random waves and their water particle velocities, that the waves in shallow water have a coherent dynamic structure of solitons and that the theoretical expression for the waves has practically sufficient accuracy in estimating their propagation.
METHOD FOR ESTIMATING DIRECTIONAL WAVE SPECTRUM IN INCIDENT AND REFLECTED WAVE FIELD
Authors: Isobe Masahiko , Kondo Kosuke
Published: June 2019

The relationship between the directional spectrum and the crosspower spectra in an incident and reflected wave field differs from the situation with no reflected waves because the phase lag between the incident and reflected waves is not random. Extra terms, which may be called phase interaction terms, exist. Hence standard methods for estimating the directional spectrum are not applicable. In the present study, the MLM is modified for this situation and the method is termed the MMLM (Modified Maximum Likelihood Method). The validity of the MMLM is examined by numerical simulation. The results indicate that the MMLM has a high resolution power. Formulas to determine the reflection coefficient are derived and their accuracy and suitability are examined.
STATISTICAL PROPERTIES OF SHORT-TERM OVERTOPPING
Authors: Kimura Akira , Seyama Akira
Published: June 2019

It has been recognized recently that large waves tend to form a group in random sea waves. Overtopping tends to occur particularly when a group of high waves attacks a sea wall. If the capacity of a storage reservoir inside the sea wall is not sufficiently large enough to store a total amount of overtopping brought about by a single group of consecutive high waves, and if a drainage facility is not large enough to pump out sufficient water from the storage reservoir before the next overtopping starts, there is a danger of flooding inside the sea wall. Hence, storage and drainage facilities should be planned to be able to cope with the total amount of overtopping produced by a single group of high waves which overtop the sea wall consecutively. The term "short-term overtopping" referred in this study is that caused by a single group of high waves (see Fig.l). This study aims to clarify the following points: (1) the statistical properties of the amount of short-term overtopping, (2) the method to evaluate a security factor inside a sea wall against flooding by overtopping and an extension of the theory to the short-term overtopping from a comparatively long sea wall.
A TYPHOON WAVE HINDCASTING TECHNIQUE
Authors: Liang N.K. , Chien C.C.
Published: June 2019

The typhoon wave forecasting technique proposed by C.L. Bretschneider (1) is a good simple method. However, the measured maximum wave height at Nan-Wan Bay (at southern tip of Taiwan) of Ida typhoon is about twice of the hindcasted maximum wave height. In general, the hindcasted maximum typhoon wave height arrives earlier than the measured data for Bretschneider's method as well as the other methods, such as Tang's and Ijima's methods. And as the typhoon is approaching the station, the hindcasted wave heights are smaller than the measured ones. On the contrary, as the typhoon is leaving the station, the hindcasted wave heights are greater than the measured heights. In order to improve these defects, the typhoon swell proposed by Liang (7) is superimposed upon the typhoon wind wave according to the energy conservation principle. The modified wave period is calculated by the energy-weighted method. In this paper 8 typhoons are as examples to show that the new method has amended the above-mentioned defects.
RUN-UP OF RANDOM WAVES ON GENTLE SLOPES
Authors: Mase Hajime , Iwagaki Yuichi
Published: June 2019

This paper investigates the following characteristics of run-up of random waves on gentle slopes experimentally: (1) the run-up wave energy spectrum, (2) the ratio of the number of run-up waves to that of incident waves, (3) the relationship between the representative run-up height, the deep-water wave steepness and the beach slope, (4) the run length of run-up heights, and (5) the effect of wave grouping on representative run-up heights. Main results are summarized in the chapter of conclusions.
WAVE GROUPS IN THE FREQUENCY AND TIME DOMAINS
Authors: Sobey Rodney J. , Read W. Wayne
Published: June 2019

The identification of wave groups in wave records is sought in terms of the classical linear analysis techniques in the frequency and time domains. Unwrapping and detrending of the phase spectrum identifies apparent order where none is assumed in the Gaussian random wave model. Similarly unexpected order is observed in the tail of the correlogram of both the wave record and the Rice envelope function. These aspects are strongly suggestive of wave grouping.
NUMERICAL SIMULATIONS OF THE 1964 ALASKAN TSUNAMI
Authors: Houston James R. , Butler H. Lee
Published: June 2019

Tsunamis are long-period water waves usually generated by earthquakes. They occur predominantly in the Pacific Ocean and can produce massive inundation and destruction. The last major tsunami that seriously impacted the United States was the 1964 Alaskan tsunami. This tsunami was generated in Alaska and caused damage in Alaska, the Hawaiian Islands, and on the west coast of the continental United States. It is the most documented of all tsunamis and the only tsunami for which there is information on the ground motion that generated the tsunami. Numerical models have been used to simulate tsunami generation and propagation. A numerical simulation of the 1964 Alaskan tsunami that included deep ocean propagation was performed by Hwang et al. (1) and a comparison was made with a deep water gage at Wake Island. Houston (2) performed a numerical simulation of this tsunami including both deep ocean and nearshore propagation in the Hawaiian Islands and presented comparisons with tide gage recordings. Although Houston (2) demonstrated the ability of numerical models to propagate tsunamis from source regions to distant shorelines, the Hawaiian Islands considered in his simulation have a very short continental shelf and the conclusions of his study might not be applicable to typical continental areas that have significantly longer continental shelves.
SHORT-CRESTED BREAKING WAVES
Authors: Machen P.C.
Published: June 2019

The likely effects of short-crested (sc) breaking waves on ships and structures are summarised in the case of the simplest non-trivial sc sea at medium/high crossing angle. Typical experimental data of sc breaking wave-height and sc water particle speeds are given at model-scale.
THE PHYSICAL BASIS OF THE MILD-SLOPE WAVE EQUATION
Authors: Behrendt Lars , Jonsson Ivar G.
Published: June 2019

The mild-slope wave equation is derived "by demanding minimum in total wave energy. By demanding conservation of wave energy, two different functionals for the finite element solution of the mild-slope wave equation are constructed. The first functional is based on a finite/infinite element formulation, and the second one is "based on a hybrid finite element formulation. Both functionals are constructed in a straight-forward way that leads to a better physical understanding of the functionals and a full understanding of each separate part of them.
THE INTERACTION OF SMALL AND FINITE AMPLITUDE LONG WAVES AND CURRENTS
Authors: Raichlen F. , Lee J.J.
Published: June 2019

The interaction of waves and currents is important for many engineering problems. For example, when considering forces on marine structures, the velocity and acceleration field must be defined, and thus the manner in which a current interacts with small and finite amplitude waves must be understood. When the current is large and oblique to the waves, the direction of the force on an offshore structure may change significantly with depth introducing a torsional moment. Wave refraction and the concomitant attenuation or amplification of waves are also affected by offshore currents. An example is the effect on incident waves of offshore currents induced by the discharge of cooling water from coastal-sited power plants. This current can modify the direction and magnitude of approaching waves, and by these changes the breaking waves at the shore and the nearshore sediment transport associated with these waves may be changed. A number of theoretical studies have been conducted on various aspects of wave-current interactions; see Peregrine (1976). One theoretical study, Thomas (1981), will be used in this investigation. Careful experiments in this area are limited; several are: Iwagaki and Asano (1980), Sarpkaya (1957), and Thomas (1981). Each of these has given attention to certain aspects of small amplitude wave-current interactions. The experiments are difficult to conduct because of the problems inherent in introducing waves into a flume with a steadyuniform current or conversely a current into a wave tank with permanent waves. Certain features of these experimental problems can be seen through the following two examples. If a plunger-wave machine were used and located at one end of a flume in which a steady current is flowing, although the waves would be developing as they interact with the current, the previously steady current would be changed to an unsteady one by the periodic blockage of the flow by the plunger. If the waves are generated at one end of the tank and allowed to develop, and a current is introduced from the bottom of the tank, this current must expand to the full depth of the flow; hence, the waves propagate on a developing current. Therefore, comparisons to theory are, to some extent, difficult to realize, because the theory generally assumes wavecurrent interactions when each is fully developed.
COMBINED REFRACTION-DIFFRACTION CALCULATIONS WITH DIRECTIONAL WAVE SPECTRA
Authors: Gaillard P.
Published: June 2019

A method of calculation of the combined effects of wave refraction, diffraction and reflection in harbours of arbitrary shape and non uniform water depth, subject to periodic or random waves is presented. Examples of application are given and practical aspects on the wave spectrum discretisation are considered.
FIELD AND LABORATORY VERIFICATION OF THE WAVE PROPAGATION MODEL CREDIZ
Authors: Dingemans M.W. , Stive M.J.F. , Kuik A.J. , Radder A.C. , Booij N.
Published: June 2019

Both the effects of refraction and diffraction may be efficiently modeled in wave propagation models by introduction of the parabolic approximation. The performance of the model CREDIZ, which is based on this parabolic approximation, was investigated in three verification studies. Two of these studies concern laboratory situations, i.e. one having a simple geometry and one having a more complicated geometry. The third study concerns a field situation, i.e. a shoal dominated area in an estuary mouth. It is found that despite the schematization to monochromatic, nearly linear wave propagation, the model CREDIZ performs remarkably well for engineering purposes.
ADDED EVIDENCE ON NEW SCALE LAW FOR COASTAL MODELS
Authors: Hallermeier Robert
Published: June 2019

Further positive results on appropriate scaling of movable bed models support an analytical expression developed in 1983. That development examined a simple parameter for a profile view of nearshore sedimentation.
ONSHORE-OFFSHORE SEDIMENT TRANSPORT NUMERICAL MODEL
Authors: Swain A. , Houston J.R.
Published: June 2019

A numerical model is presented for calculating beach profile development due to offshore sediment transport and tested with laboratory and field data. The model allows variable wave conditions, water level fluctuations due to tide and storm surge, arbitrary bathymetry, and arbitrary sediment size. The agreement between calculated and measured beach profile erosion is good.
MEASUREMENTS OF BEDLOAD TRANSPORT IN THE NEARSHORE ZONE USING RADIOISOTOPIC SAND TRACERS
Authors: Drapeau George , Long Bernard
Published: June 2019

A field study was conducted on the North Coast of the Gulf of St. Lawrence in Eastern Canada to evaluate sediment transport processes in a coastal area that would be affected by the modification of river regimes for hydropower production. Radioactive tracers were used to evaluate the mobility of coastal sediments. Three injections were carried out using Neodynium 147 (half-life 11.1 days), at 450, 550 and 2200 m. from the shoreline at depths from 3 to 10 m. The high sensitivity of the detection system allowed to monitor the study area for 44 days. The tagged sediments responded to waves and tidal currents and were sensitive to minor changes. Comparison of the patterns of evolution of the three injections permitted to evaluate the relative mobility of bottom sediments as a function of water depth and distance from shore. Bedload transport rates were calculated but they are related to specific events such as storms within the Gulf of St. Lawrence more than to steady state conditions.
TRANSPORT OF NILE SAND ALONG THE SOUTHEASTERN MEDITERRANEAN COAST
Authors: Carmel Zev , Inman Douglas L. , Golik Abraham
Published: June 2019

The potential for longshore sediment transport (LST) is estimated from a three-year set of directional wave data measured off Haifa, Israel. The resulting annual cycle of LST, together with an analysis of the wave and shore characteristics, suggests a wave-induced sediment transport mechanism with a uni-directional annual transport that gradually decreases along the transport path from the source (Nile delta) to sink (Haifa Bay). Existing estimates of the rates of transport of Nile sediment are in good agreement with this result.
FLOW RESISTANCE DUE TO INTENSE BEDLOAD TRANSPORT
Authors: Hanes Daniel M.
Published: June 2019

When water flows over a stationary bed the fluid motion is retarded by both skin the friction and local pressure gradient forces related to the roughness of the bed. If the bed itself is composed of discreet movable grains, the boundary is less clearly defined and the dynamics poorly understood (see Gust and Southard, 1983). Owen (1964) proposed that saltating grains (grains which lift off the bed, move through the fluid, and fall back to the bed without colliding with other grains) have the effect of increasing the frictional resistance of the bottom. At higher flow stages, Hanes and Bowen (1984) have suggested a model for bedload transport which is based upon the dynamics of collisional grain flows following Bagnold (1954, 1956). In such a collision dominated flow, it appears that the resistance of the bed to the overlying flow can be less than the resistance of a fixed bed to the same overlying flow. This result is consistent with the dynamics of rapid granular-fluid flows, as will be discussed below.
CALCULATION OF THE RATE OF NET ON-OFFSHORE SEDIMENT TRANSPORT ON THE BASIS OF FLUX CONCEPT
Authors: Deguchi Ichiro , Sawaragi Toru
Published: June 2019

Time and spatial variations of sediment concentration of both bed load and suspended load in the process of two-dimensional beach deformation were investigated experimentally. At the same time, the relation between the velocities of water-particle and sediment migration was analyzed theoretically. By using those results,a net rate of on-offshore sediment_ transport in the process of two-dimensional model beach deformation qf was calculated on the basis of sediment flux. It is found that Qf coincides fairly well with .the net rate of on-offshore sediment transport calculated from the change of water depth.
A NUMERICAL SIMULATION TO TRANSIENT WAVE INDUCED HARBOR OSCILLATIONS USING BOUNDARY ELEMENT TECHNIQUE
Authors: Demirel Vedat , Wang Shen
Published: June 2019

A new numerical technique for solution to transient linear long wave induced oscillations is introduced. It is based on the boundary element method, which is well recognized by its numerical efficiency and convenience. Several harbor models are investigated. Advantages of the proposed method as compared to the existing techniques are discussed.
COASTAL ENGINEERING STUDIES FOR INSHORE MINING OF DIAMONDS AT ORANJEMUND
Authors: Moller J.P. , Owen K.C. , Swart D.H.
Published: June 2019

This paper describes a diamond mining operation on the west coast of Africa in Namibia (South West Africa, see Figures 1a and 1b), where a sea-wall of normal beach sand has been built out to a distance of more than 300 m seawards of the original coastline. The wall which runs alongshore is maintained in the high energy environment, which is characterized by northbound longshore transport rates, by means of artificial suppletion at a rate of up to and more than 300 000 m / month. Before embarking on the project the company had to be assured of the sand on the sand-wall; to allow completion of the project free of severe damage by wave action. This implied being able to predict the erosion rate of the sea-wall by the waves. The data set used consisted of wave measurements by Waverider and wave observations obtained from voluntary observing ships; aerial photographs at monthly intervals of the waterline in the study area; and soundings of the beach, sea-wall and nearshore topography by using a helicopter as a platform. Various methods of prediction and projection were used to quantify sediment movement.
NUMERICAL SIMULATION OF BEACH PROFILE CHANGES
Authors: Nishimura Hitoshi , Sunamura Tsuguo
Published: June 2019

This paper presents an overall numerical model for predicting beach profile changes due to waves. The local rate of net on/offshore sediment transport is empirically formulated as a function of the Ursell number and Hallermeier parameter. A sub-model of two-dimensional wave transformation includes the wave shoaling, breaking and damping in a surf zone. It is combined with another sub-model of beach profile change for the analyses of wave-profile interaction. The validity of the model is examined through hindcasting of profile changes observed in ordinary and prototype-scale flumes.
DESIGN OF BEACH NOURISHMENT SCHEME
Authors: Pilarczyk K.W. , Van Overeem J. , Bakker W.T.
Published: June 2019

An artificial beach nourishment used to replenish an eroding part of a coast may seem expensive and the need for repetition may discourage coastal managers. However, careful considerations of capital and maintenance cost frequently prove that it may be, in fact, the optimum solution. An added advantage is that the recreational function of the beach is preserved. In spite of a great number of research-reports and publications on coastal processes and beach nourishment, the practical applicability of this knowledge is still in an initial stage, i.e. formulating the general concepts and trying to test their validity and practical applicability. On the other hand, the solution of many practical coastal engineering problems cannot wait until complete understanding of these processes and the existing knowledge on this subject (though limited) should be made available for designers and managers involved in coastal engineering. This was the main reason for the Rijkswaterstaat (Dutch Public Works Department) to prepare a manual on artificial beach nourishment. In 1983, this Department established the task-group 'Profile Formation of Beaches', with the aim to study the relevant aspects of beach nourishment. These aspects concern among other things the influence of a beach fill on the coastal morphology and the environment, and the design and execution of a beach nourishment scheme. The members of the task-group originate from various governmental departments, research institutes (Delft Hydraulics) and private organisations (Volker Stevin Dredging, Zanen Verstoep Dredging Contractors). In addition to the members of the working-group some other persons and organizations (also outside the Netherlands) have contributed to the final report. The results of the studies have been described in a Manual on Beach Nourishment (Manual, 1986). This manual contains both theoretical and practical information, and is intended for persons and organisations who are involved in the prevention of beach erosion. Nearly all available and relevant literature to this subject has been incorporated. The actual paper reviews part of the contents of the Manual and summarizes aspects related to the aim, the different types and the design process of beach nourishment schemes.
ANALYSIS OF A BEACH QUALITY PROBLEM
Authors: Prestedge Gordon K. , Fleming Christopher A.
Published: June 2019

A study was recently undertaken to investigate sediment transport on a section of coastline where recreational beaches have experienced periodic erosion. Alongshore, onshore/offshore and aeolian sediment transport processes were investigated and quantitative transports predicted with the aid of calibration using surveys and aerial photographs. This paper describes the study and the recommendations proposed for beach quality improvements.
SHORE PROCESS ALONG THE COAST OF IWO-JIMA
Authors: Shigemura Toshiyuki
Published: June 2019

Iwo-jima is a small isolated volcanic island located in the Pacific Ocean. Due to the continuous upheaval of the island, foreshore area of this island has been increasing since 1911. Investigation is made to clarify the variation of the foreshore area of this island by analyzing the various field data obtained during the past three years. Analyses reveal that the foreshore area is currently increasing at an approximate rate of 180,000 square meters per year due to the unusual upheaval of the island exceeding 45 centimeters per year although seasonal variation of the foreshore area reaches 300,000 square meters.
REDUCTION PROCESS OF CROSS-SECTIONAL AREA AT RIVER MOUTH
Authors: Shimizu Takuzo , Kondo Kosuke , Kajima Ryoichi
Published: June 2019

Reduction processes of the cross-sectional area at a river mouth were investigated on the basis of numerical simulations and field measurements, in order to predict the possibility of closing of the mouth of the Samegawa River, Fukushima, Japan. As a result, it was found that the decrease in tidal prism, induced by a reduction of the cross-sectional area, had an important effect on the closing of the river mouth. By considering this effect and estimating the sediment transport rate properly, a practical prediction model was successfully established for simulating the reduction processes of the crosssectional area at the river mouth.
PREDICTION OF WIND-DRIVEN TRANSPORT RATE
Authors: Swart D.H.
Published: June 2019

The rate of wind-driven sand movement in a dune field is an important parameter needed to establish management strategies for sand dune fields. Until recently not much attention has been given in engineering circles to the possible effect of wind-blown sand transport. However, there is a wealth of literature on the subject which goes back as far as 1936. A study of literature reveals that there are at least 16 formulae for the prediction of the aeolian transport rates which are readily available. This paper describes a technique which utilizes these 16 formulae in the most effective manner for predicting the best estimate of the potential wind-blown transport rate. Restrictions on the applicability of the method are discussed and fields for further research are recommended.
MATHEMATICAL MODELLING OF WAVE-INDUCED NEARSHORE CIRCULATIONS
Authors: Yoo Donghoon , O'Connor Brian A.
Published: June 2019

The paper presents a mathematical model for describing wave climate and wave-induced nearshore circulations. The model accounts for current-depth refraction, diffraction, wave-induced currents, set-up and set-down, mixing processes and bottom friction effects on both waves and currents. The present model was tested against published experimental data on wave conditions within a model harbour and shown to give very good results for both wave and current fields. The importance of including processes such as advection, flooding and current-interaction in coastal models was demonstrated by comparing the numerical results without each process to the results from the complete scheme.
2DH COMPUTATION OF TRANSIENT SEA BED EVOLUTIONS
Authors: De Vriend Huib J.
Published: June 2019

The interaction between the constituent models for waves, currents, sediment transport and bottom level changes in a class of compound 2DH mathematical models of transient sea bed evolutions in the coastal zone is investigated mathematically, using the theory of characteristics and a harmonic analysis technique. This leads to contrary indications as to the importance of including diffraction in the wave model and to the unambiguous conclusion that the bottom slope effect on the sediment transport is indespensable for the mathematical system to be inherently stable. This conclusion is shown to imply that depth-integrated current model are insufficient to describe the flow in this type of morphological computations for the nearshore zone or complex coastal areas.
DYNAMIC STABILITY OF ROCK SLOPES AND GRAVEL BEACHES
Authors: Van der Meer J.W. , Pilarczyk K.W.
Published: June 2019

More than 150 tests have been analyzed in order to describe the dynamically stable profiles of rock slopes and gravel beaches under wave attack. Relationships between profile parameters and boundary conditions have been established. These relationships have been used to develop a computer program. This program is able to predict the profiles of slopes with an arbitrary shape under varying wave conditions, such as those found in storm surges and during the tidal period.
SCOUR AROUND STRUCTURES
Authors: Bijker Eco E.
Published: June 2019

The physics of scour around structures and especially underneath pipelines is discussed. It is demonstrated that a combination of current and waves with an equal bottom shear stress as a uniform current gives lower scour rates than a single current with the same bottom shear stress. The principle of the performance of scale series is discussed and it is shown that this method has still some weak points.
THE RELATIONSHIP BETWEEN WAVE LENGTH AND WEIGHT OF ARMOUR BLOCKS
Authors: Chen Kuo-Quan , Kao Ruey-Chy , Tang Frederick L.W.
Published: June 2019

Every coastal engineer realizes that the weight of armour blocks decided by Hudson's formula is safe enough for short steep waves, however, suffering damage from long period swells, even though the incidental wave height is the same. Several corrections have been made and submitted to ICCE as well as in other occasion. The authors try to explain analytically the influence of wave length on the design weight of armour blocks and justify by much of experiments in order to offer new formula and graphs for practical application.
WAVE TRAPPING BY BREAKWATERS
Authors: Dalrymple Robert A. , Kirby James T. , Seli Daniel J.
Published: June 2019

The refraction of water waves around the heads of breakwaters can lead to large wave heights along the sheltered side of the structure. These waves are shown to be edge waves, trapped on the breakwater, based on the comparison of laboratory data and linear edge wave theory.
PIER PROTECTION SYSTEM FOR THE DUWAMISH SHIP CHANNEL IN SEATTLE
Authors: Eisenberg Y.
Published: June 2019

In 1978 an out-of-control ship hit and severely damaged a bascule bridge across the Duwamish West Waterway in Seattle seriously affecting both ship and highway traffic. The high level West Seattle Bridge was subsequently constructed to handle all through-highway traffic. A swing bridge was also designed to handle local traffic over the ship channel. The function of the pier protection system described in this paper is to protect the pivot piers and swing spans of this new bridge from damage by absorbing the part of the tranverse energy component imparted by a colliding ship, which is not absorbed by deformation of the ship's hull.
STABILITY ANALYSIS OF OCEAN PIPELINES : A PROBABILISTIC APPROACH
Authors: Geustyn Leon C. , Retief Gideon de F.
Published: June 2019

A probabilistic approach to the lateral stability of a pipeline on the sea-bed is considered. The uncertainties involved in the deterministic approach, due to the stochastic nature of variables, inaccuracy of models and statistical error are discussed. Variables representing these uncertainties are identified and their statistical properties investigated. Procedures for computing the probability of stability failure are developed using both analytical and Monte Carlo simulation techniques. Example calculations are presented indicating typical applications. It is concluded that the probabilistic procedure, as presented here, can serve as a valuable tool in the stability analysis of ocean pipelines.
BEACHWALLS FOR BEACH EROSION PROTECTION
Authors: Hayashi Ralph M.
Published: June 2019

Many shoreline property owner protect the beaches from erosion walls. In many situations, these sea increase in beach erosion forcing, adjoining properties to construct their shoreline. The construction o causes erosion on the adjacent prop more often than not, where beach construction of sea walls in addi erosion to adjacent property has cause of the beaches. s, in an effort to have constructed sea walls have caused an by "domino effect", sea walls to protect f a sea wall often erty. Unfortunately, s once existed, the tion to causing beach ed the disappearance Because of the concern for the eroding beaches and the proliferation of sea walls, the design of a "beachwall" was proposed over four years ago by the author. Several of these beachwalls have been constructed, and the beaches fronting these structures have thus far been preserved or restored.
FLOW COMPUTATIONS NEARBY A STORM SURGE BARRIER UNDER CONSTRUCTION WITH TWO-DIMENSIONAL NUMERICAL MODELS
Authors: Klatter H.E. , Dijkzeul J.M.C. , Hartsuiker G. , Bijlsma L.
Published: June 2019

This paper discusses the application of two-dimensional tidal models to the hydraulic research for the storm surge barrier in the Eastern Scheldt in the Netherlands. At the site of the barrier local energy losses dominate the flow. Three methods are discussed for dealing with these energy losses in a numerical model based on the long wave equations. The construction of the storm surge barrier provided extensive field data for various phases of the construction of the barrier and these field data are used as a test case for the computation at methods developed. One method is preferred since it gives good agreement between computations and field data. The two-dimensional flow patterns, the discharge and the head-difference agree well,, The results of scale model tests were also available for comparison. This comparison demonstrated that depth-averaged velocities, computed by a two-dimensional numerical model, are as accurate as values obtained from a large physical scale model. Even compicated flow patterns with local energy losses and sharp velocity gradients compared well.
MEASUREMENT OF REFLECTION COEFFICIENT OF SEAWALL IN OMORA BAY
Authors: Kondo Kosuke , Akama Masayuki , Isobe Masahiko
Published: June 2019

Field investigations were performed in order to establish the reflecting characteristics of a steel sheet-piling type seawall and two vertical wave-dissipating type seawalls through directional wave measurements of wave reflection systems. A pre-designed line array of several capacitance-type wave gauges was used to measure the wave field just in front of the seawall, and the MMLM (Modified Maximum Likelifood Method) was applied for the calculation of the directional wave spectrum and the reflection coefficient. The estimated directional spectra demonstrated that the MMLM has high resolution power and can sufficiently separate the incident and the reflected wave energies. As a result , it was found that the reflection coefficient of the vertical steel sheet-piling seawall is about 0.9 and is independent of the incident wave conditions, whereas those of the vertical wave-dissipating type seawalls show considerable change in correlation to the incident wave period or the mean water level.
ON THE FLOATING BREAKWATER - A NEW ARRANGEMENT
Authors: Lee C.H. , Twu S.W.
Published: June 2019

A new type of floating breakwater composed of net-tubes and buoy-balls is presented in this paper. A series of model studies have been carried out for several arrangements of this structure. As wave damping effect is concerned, a case that the structure being set vertically is shown to be better than the one being set horizontally, while more than two rows of the structures are set vertically and separately, a case which being connected with ropes between adjoining rows is proved to be better than the case without connecting ropes.
WAVE UPLIFT ON PLATFORMS OR DOCKS IN VARIABLE DEPTH
Authors: Lee Jiin-Jen , Lai C.P.
Published: June 2019

Wave uplift forces on two dimensional platforms or docks in a variable depth medium has been studied theoretically and numerically. The incident waves are non-linear waves with maximum amplitude greater than the clearance between the still water surface and the underside of the platforms or docks. The flow is assumed to be inviscid, irrotational without ambient current. Thus, the theoretical model solves the Laplace equation along with full nonlinear free surface conditions. In order to conveniently handle the moving free surface in an irregular bottom topography with the presence of platform or dock an isoparametric mapping technique was used to transfer the fluid domain and its boundaries into a regular geometry. A Galerkin finite element model is developed to model the transformed fluid region. The resulting discrete equations are solved iteratively by using adaptive Line SOR (Successive-Over-Relaxation) technique. Artificial viscosity is included in both the dynamic and kinematic free surface equations to damp out the free surface oscillations in the front region of the platform or dock. The Runge-Kutta method is employed to integrate the time variation in the nonlinear free surface equations. Results obtained by the numerical method were compared to the available experimental data obtained by others in order to demonstrate the workability of the proposed algorithm.
NEARSHORE CIRCULATIONS DUE TO WAVE INDUCED CURRENTS BY OFFSHORE BREAKWATER IN FINITE ELEMENTS
Authors: Liang Shinn-Chung
Published: June 2019

The objective of the present study is concerned with the numerical prediction of wave patterns and wave induced currents adjacent to a breakwater. The wave theory used is that of Berkhoff's (1972) mild slope wave equation with effects of diffraction, refraction and reflection described as Bettess, Liang and Bettess (1984). A finite element model is applied with appropriate boundary conditions. The singularity in the velocity at the tip of the breakwater is modelled effectively using the technique of Henshell and Shaw (1975), originally developed for elasticity. In the case of waves induced currents a potential representation of velocity in the fluid has be€>n used to derive a set of radiation stress expressions based on the theory of Longuet-Higgins (1964, 1970a,b), which are for an arbitrary wave pattern and the bottom variation. These expressions used account for the mean sea level and satisfy Mei's (1973) static balance of momentum flux. The radiation stress is applied to obtain forcing terms for use in a shallow water equation in conjunction with limiting ratio wave breaking where wave height, wave period, wave steepness and beach slope may be considered. Finally, an offshore breakwater on a beach for shore protection has been applied in a complete finite element model to predict both wave pattern and nearshore currents. Two angles of wave incidence are chosen. A series result has been produced.
EFFECTS OF SHORT-CRESTED WAVES ON THE SCOURING AROUND THE BREAKWATER
Authors: Lin Ming-Chung , Wu Chi-Tung , Lu Yen-Chi , Liang Nai-Kaung
Published: June 2019

The aim of this research is to investigate quaiitatively the influence of short-crested waves on the scouring around the breakwater through mainly some laboratory studies. At first, we succeed to observe clearly in laboratory some sedimentary bed forms such as troughs, holes, triangle bars and longitudinal bars under short-crested wave actions. Then we elucidate the associstion of their formation mechanism with theory of short-crested waves, also indicate its effect on scouring at the toe of breakwaters. In addition, it is shown that the breaking wave height of short-crested waves is certainly higher than that of twodimensional standing waves. Finally we demonstrate some facts of failure of breakwater caused by short-crested wave breaking basing on some field results.
ON STRESS IN TETRAPODS UNDER WAVE ACTION
Authors: Nishigori Wakiro , Endo Taiji , Shimada Atsuyuki
Published: June 2019

Recently, as well as hydraulic stability, structural strength of armor blocks has emerged as a major problem in breakwaters. This problem is studied by research organizations in many countries. In Nippon Tetrapod Co., Ltd., a series of hydraulic model tests was conducted to measure the surface strain on Tetrapods under wave action. In this paper, the results of the hydraulic model test are described. Prior to the hydraulic test, a similitude relation on impact stress and strain between the prototype and model was derived and a drop test was performed to investigate the scale effect on impact strain on Tetrapods. The hydraulic test was conducted to measure the surface strain on 50kg model Tetrapods using strain gages. In addition, impact strain on 50t Tetrapods under wave action was estimated applying the similitude relation. The strain on Tetrapods under wave action was clarified through this study.