bluuebunny/crossref_metadata_2025 huggingface dataset:
ON THE BEHAVIOR OF ARMOR UNIT IN THE COVERLAYER
Authors: Pertenscky Hans Werner , Rutte John , Schmidt Reinold
Published: June 2019

As a result of the large-scale failure of the rubblemound breakwater at SINES, Portugal in 1978 a number of research programs were begun. At present, however, very little information is available from technical publications regarding new design criteria, recommendations, or test procedures for model tests of rubblemound breakwaters. The need still exists, therefore, for economically practical model tests and standardized test procedures so that more tests can be conducted and reproducible results from different institutions can be compared. At the same time, a number of factors related to the stability of rubblemound surface elements, and the interrelationships between those factors, have not been adequately examined or explained. Apparently without extensive model tests, for example, it has been suggested that greater stability can be obtained by using elements with greater unit weights (comparing elements of the same absolute weight) , either by adding scrap metal or denser materials, such as granite, to the concrete. Furthermore, susceptibility to breakage is of major importance to the long-term stability of armour layer units, particularly for dolos and similar less massive element types. This aspect has been generally neglected in laboratory tests, however, and attempts to simulate the lower ultimate strength of elements in reduced-scale model tests appear extremely difficult, as well as costly in terms of time and materials. Several other factors which can significantly affect the stability of an armour layer include the surface roughness of the individual elements, as well as boundary conditions such as the beach slope.
A UNIQUE INSTRUMENTATION SCHEME FOR MEASURING LOADS IN MODEL DOLOS UNITS
Authors: Scott R.D. , Turcke D.J. , Baird W.F.
Published: June 2019

An instrumentation scheme for the measurement of the structural response of dolos units in a physical model due to static and quasistatic forces is presented. This was achieved by the development of a specialized armour unit "load cell". The load cell was tested under a variety of loading conditions ranging from static point loads to the complex forces arising from simulated prototype wave action. In the final stage of testing, a model breakwater was constructed and analyzed. The results of these tests demonstrated the accuracy of the developed instrumentation and the feasibility of its use for measurements conducted in physical models. Knowledge of the structural response of armour units in the breakwater environment may be incorporated into an improved overall design procedure for armour units that considers both the hydraulic stability and the structural integrity of the individual units.
CRITICAL RUN-UP HEIGHT ON THE SEA WALL
Authors: Seyama Akira , Kimura Akira
Published: June 2019

This study aims at clarifying the difference between irregular and periodic wave run-ups on a slope or a sea wall. Since hydraulic phenomena on a slope are the induced result of an interaction between a running up wave and a back-wash. The run-up height, therefore, has to be investigated in terms of a back-wash properties in addition to run-up wave properties. The experiments which are so designed that waves can run up on a slope without meeting back-wash, were conducted to evaluate the back-wash effects. The relative run-up heights K /HQ of periodic waves in these experiments reached up to about two times as high as those of periodic waves which have the same steepnesses. The run-up heights of irregular waves on a slope were also investigated experimentally. There are no clear relations between R_/HQ and HQ/LQ as those for periodic waves ordinary observed, and they distributed widely. The upper-most value of RJ-/HQ in the distribution for any HQ/LQ was almost equal to the value in the above experiment. The uppermost (critical) relative run-up heights RJ-/HQ for the given HQ/LQ and slope may exist. The differences between the critical and ordinary run-up height of periodic waves on the sea wall were also experimentally investigated. The difference is prominent when a sea wall is set onshore from the shore-line. It reaches up to about 4 times when a sea wall is set a little on-shore from the shore line. Some statistical discussion on the probability of the situation in which the critical run-up may be brought about is given at the last part.
DESIGN AND EVALUATION OF BEACH PROTECTION SCHEMES
Authors: Swart D.H. , Horikawa K.
Published: June 2019

On the basis of eleven poster presentations on beach protection schemes and/or devices, at the recent 20th International Conference on Coastal Engineering, the various levels involved in the design and evaluation of beach protection schemes are discussed in this paper. These are: (1) the assessment of the problem and processes operative in the area; (2) the establishment of an overall master plan for development; (3) the design stage; (4) the construction phase, and (5) the post construction phase. It is concluded that it would be useful if some form of international co-operation could be instigated to allow the collation of techniques used at the various levels in one handy location, for dissemination by all contributors.
TRANSMISSION OF RANDOM WAVES THROUGH PILE BREAKWATERS
Authors: Truitt Clifford L. , Herbich John B.
Published: June 2019

Several previous investigators have conducted experiments leading to expressions for predicting the transformation of waves passing through closely-spaced pile breakwaters. The present study extends those earlier experiments using monochromatic waves to the case of a spectrum of random waves. Records of incident waves and of waves after transmission through a model pile breakwater were compared to determine a coefficient of transmission. Results are presented for several cases of pile spacing and pile diameter. Good agreement is found between observed transmission coefficients and those predicted using the expression proposed by Hayashi et al. (1966).
WAVE DIFFRACTIONS BY ROWS OF VERTICAL CYLINDERS OF ARBITRARY CROSS SECTION
Authors: Yoshida Akinori , Iida Norio , Murakami Keisuke
Published: June 2019

Wave diffractions by a number of (a group of or a row of) vertical cylinders have been investigated in connection with, e.g., multilegged offshore structures (Spring and Monkmeyer(1974), Ohkusu(1974), Chakrabarti(1978), Mciver and Evans(1984), etc.); Wave-Power absorption devices (Miles (1983), Falnes(1984) , Kyllingstad(1984) , etc.); Wave barrier systems (Massel(1976), Kakuno and Oda(1986), etc.). Most of the previous works were, however, mainly aimed at the wave diffractions by cylinders of circular cross section and/or by cylinders of relatively small dimensions compared to wave length. In this paper, we describe a simple yet versatile analytical method to solve wave diffractions by infinite rows of vertical cylinders. In the method, it is assumed, in addition to usual linearised small amplitude assumptions, that: the row of cylinders is composed of infinite number of surface-piercing evenly spaced equal cylinders fixed on sea bottom; incident wave direction is perpendicular to the row; the number of rows may be arbitrary, at least in principle; the cross sectional shape of the cylinders may be arbitrary as long as it is symmetrical with respect to the incident wave ray; and the cylinders are relatively large compared to incident wave length so that inertial forces are predominant to drag forces.
EXPERIMENTAL STUDY ON THE VALIDITY RANGE OF VARIOUS WAVE THEORIES
Authors: Hattori Masataro
Published: June 2019

In the design of coastal structures and the study of nearshore dynamics, rational predictions of the wave kinematics are very important but difficult procedures. Although a large number of nonlinear wave theories have been proposed and used for computing the wave kinematics, there are no theories applicable from the deep water to very shallow water. It is, therefore, very important for coastal researchers and engineers to know which of theories describe well a wave field specified by the wave characteristics and water depth, and to select a particular wave theory for a problem of interest. Many intensive efforts have been made to examine the validity as well as the applicability of various wave theories. However, there are still no well-accepted guidlines for the application range of the wave theories. The validity evaluation of a particular wave theory has been basically made by means of the following two versions: the analytical (mathematical) validity and the experimental (physical) validity. The analytical validity study has been conducted by various researchers (Dean, 1970; Komar, 1976; Horikawa et al., 1977; Swart, 1978) and revealed the degree of mathematical satisification to the governing equations and boundary conditions for each wave theory. The analytical validity study probably tends to show the relative applicability for various wave theories. It does not ensure that the theory describe well laboratory or field phenomena. Based on the analytical validity of various wave theories by Horikawa et al., Isobe (1985) proposed application ranges for the finite amplitude wave theories in terms of the relative water depth and relative wave height. The experimental validity refers to how well the prediction of various wave theories agrees with actual measurements (Dean & Dalrymple, 1984). As the wave shoals, wave form becomes more asymmetrical, especially under high wave conditions of interest to design. Such nonlinearity influences greatly the wave kinematics and it makes difficult to predict readily the wave kinematics by several theories. From a practical viewpoint, it is , therefore, requested to establish the application ranges of available wave theories for shoaling waves.
FEASIBILITY STUDY OF DEEP WATER PORT OF TAIWAN DISTRICT
Authors: Hou H.S.
Published: June 2019

Taiwan is now served by five international ports, two of which were newly opened since 1970. They have been under continuous expansion in recent years to meet the needs of the island's burgeoning foreign trade. Due to recent trend of vessel developed to huge load-capacity, the existing port of Taiwan district is inconvenient to the ULCC or VLCC - for decreasing the shipping cost and accomodating the cargo handing of over 100,000 DWT, the deep water port is urgent to be developed in order to promote the competent capability of port cargo handling. This research is divided into two parts, at first, the prediction of cargo handling and the cargo sources which are adapted to the huge vessel shipping need to be studied for the development of deep water port, the next, then the oceanographical data for the design and the planning of deep water wharf and breakwater need to be surveyed around this Island for possible site of deep water port. This study deals with the related problems of deep water breakwater construction and discusses how to apply the present design and construction method to the deep water wharf and breakwater. Further analyses are conducted for this research in the coming three fiscal years.
ON THE CONSTRUCTION OF HSIN-TA LNG TERMINAL IN TAIWAN
Authors: Lai Shih-sheng Paul , Lee Cheng-shiun
Published: June 2019

Since 1984 Hsin-Ta LNG Terminal has been under construction for the purpose of importing liquefied natural gas because of increasing demand and possible depletion of natural gas in Taiwan. Several alternatives were taken into account during the feasibility study. The Terminal is built with only a southern breakwater due to its good natural coastal conditions. Each construction item has been coordinated closely in order to advance the schedule. The first phase of land reclamation was finished by 1986. Three tanks have been under construction since soil improvement was finished. The entire project will be completed in 1989.
THE INFLUENCE OF WAVES ON THE HYDRAULICS OF SEA OUTFALLS
Authors: Larsen Torben
Published: June 2019

Most of the larger cities in Denmark are located near the sea. About 60% of the sewage is therefore discharged through sea outfalls. Most of these sea outfalls were built in the seventies. In most cases a plastic pipeline were used, and the pipeline was ballasted with armoured concrete blocks and burried in a trench 1 - 2 m underneath the seabottom. To give the necessary initial dilution a diffusor with one or several contracted, horizontal outlets ends the pipeline. The Danish coasts are in general shallow and exposed to waves. The littoral sanddrift is considerably and the sea outfalls need to cross one or more bars. The diffusors are often placed outside the bars, but nevertheless sediment transport can occur around the diffusor. Figure 1 gives some typical data for Danish sea outfalls.
100 YEARS OF FORESHORE RECLAMATION IN SINGAPORE
Authors: Pui S.K.
Published: June 2019

Singapore is an island republic with about 10% of her land area reclaimed from foreshore during the last century. In this Paper, past reclamation works are reviewed and possible future reclamation works are predicted.
WAVE-INDUCED EFFECTS IN A COOLING WATER BASIN
Authors: Raichlen Frederic
Published: June 2019

Wave-induced effects have been observed in a model of the cooling water intake basin of the Pacific Gas and Electric Company's Diablo Canyon Nuclear Power Plant. This model, built to an undistorted scale of 1:45, was constructed initially to study the design for the repair of the terminus region of the West breakwater damaged in storms of January 28, 1981. It was decided by PG&E to investigate, in the same model, the forces due to waves acting on two air intake structures for the auxiliary saltwater pumps and the pressures or. the external and the internal walls and the ceiling of the cooling water intake structure located in the manmade cooling water intake basin. During the course of the experiments it was noticed that the mean water level in the breakwater enclosed basin changed as a function of the incident wave characteristics. This allowed waves to overtop the cooling water intake structure which, without the change in mean water level, would not have occurred. It is this difference between the mean water level and the still water level inside the cooling water basin, defined as ponding, which will be reported herein. Diskin, et al. (1970) investigated this effect behind low and submerged permeable breakwaters in a two-dimensional wave tank model. As was mentioned by them, in normal breakwater tests it is a common practice to provide some means of communication between the seaward and shoreward side of the breakwater so that precisely this mean water level change due to overtopping of the structure does not occur. For their experiments the change in mean level varied from about 5% of the deep water wave height to 32% of the deep water wave height depending upon the submergence of the breakwater crest; the smallest change corresponded to the largest depth over the breakwater crest. This effect was discussed by Dalrymple and Dean (1971), and they proposed an analytical model based on the conservation of mass. The estimated inflow was equated to an estimate of the return flow over and through the permeable structure. Some limited agreement with the results of Diskin, et al. (1970) were shown.
SURFACE CURRENTS REMOTELY OBSERVED BY MEANS OF RADAR
Authors: Schirmer F. , Essen H.H. , Gurgel K.W.
Published: June 2019

Surface currents normally are difficult to measure. Only a set of Lagrangian drifters observed from fixed stations or from an aircraft or by satellite can give adequate information. Beneath this there is a new and powerfull field measuring tool which functions with a decametre backscatter radiowave RADAR. Two (or more) such fixed RADAR stations on land or on islands can remotely measure the surface currents in front of them with high resolution in space and time. This paper has two aims: first, to give a short explanation of the physical principles of the backscatter RADAR and to show its requirements and its limits, and secondly, to demonstrate the possibilities offered by this RADAR with an example of the coastal surface current off Norway.
STUDIES ON THERMAL DIFFUSION AND VERIFICATION OF THE THIRD NUCLEAR POWER PLANT IN TAIWAN
Authors: Tang K.C. , Tsai M.T. , Hwang Y.R. , Hwung H.H.
Published: June 2019

In general, hydraulic model tests and numerical simulations can be used for securing enough informations in order to assess the environmental impact by thermal discharge after the power plant operation. However, the numerical simulations should be verified by the consequence of hydraulic model tests or the field data. Then, the numerical model can be used as a prediction model to foresee the nature of thermal diffusion when the additional generators will be operated. The third nuclear power plant in Taiwan has been constructed in 1984. In order to protect the abundant corals which distributed on the rocky bottom around this power plant, a complete studies on thermal diffusion have been performed, accordingly, a verification with field measurements were also made in this paper.
COOLING WATER RECIRCULATION IN THE OCEAN
Authors: Wiegel Robert L. , Wells John T. , Murdoch Michele A.
Published: June 2019

In some configurations of cooling water systems for thermal-electric power plants, which use sea water as a source, a certain amount of recirculation occurs. A theory is developed to predict this recirculation.
STUDIES ON THE CORRELATION OF TIDAL ELEVATION CHANGES ALONG THE WESTERN COASTLINE OF TAIWAN
Authors: Hwung H.H. , Tsai C.L. , Wu C.C.
Published: June 2019

In order to understand the characteristics of tidal elevation changes along the western coastline of Taiwan, the authors collected the tidal records at the same duration from eleven stations and made an elaborate analysis in this paper. First step, the main tidal constituents were picked out from spectrum analysis, and the amplitudes and phase angles of these tidal constituents would be obtained by harmonic analysis. Then the variations of amplitude and phase lag of the main constituents and the variations of mean high water level and mean low water level along the coastline would be presented in the figures respectively. Finally, based on the results of harmonic analysis, the energy density of tide for every station could be calculated separately, and the location of the maximum energy density would be determined by cubic spline method.
BREAKING CRITERION ON NON-UNIFORMLY SLOPING BEACH
Authors: Izumiya Takashi , Isobe Masahiko
Published: June 2019

This paper deals with the breaker height on non-uniformly sloping beaches. A large number of experiments were carried out to obtain a breaking criterion on bar and step-type beaches. Based on the experimental data, a relationship among the breaker height, water depth, and wave period is investigated for various bottom configurations. As a result, the breaker height on non-uniformly sloping beaches is found to be well predicted by substituting an equivalent bottom slope in Goda's breaker index which has been obtained for uniformly sloping beaches. The equivalent bottom slope is defined as the mean slope in the distance of 5hg offshoreward from a breaking point, where hg denotes the water depth at the breaking point. The method for calculating the breaker height on natural beaches is also presented.
MEASUREMENTS FROM A FAST-MOVING AIR-CUSHION PLATFORM
Authors: Kerchkaert P. , Grobben A. , De Candt P.
Published: June 2019

In 1976 the Belgian Government decided to enlarge the harbour of Zeebrugge and to execute an artificial beach renourishment on the beaches at Knokke-Heist. A comprehensive survey program along the 24 km coastline was conceived using remote sensing techniques. This enabled correct momentary recordings of the beach areas, the production of differential charts and calculations of dune and beach volumes. However, the observations of the nearshore and offshore areas from ordinary survey vessels take too long so that no accurate momentary recordings of the seabottom topography can be achieved. On these grounds, in 1983, the Belgian Authorities have instructed the Eurosense Belfotop Company to develop an effective measuring method based on the use of a hovercraft. This hovercraft platform, named "BEASAC" and designed for hydrographic surveys, is now used for monitoring the coastal morphology and the dredging activities in the access channels to the major Belgian seaports. On the basis of the "Beasac"-soundings of the nearshore area and the aerial remote sensing data of the beach, charts and differential charts of the combined beach and nearshore area are produced. The results of this technique are very promising and will be incorporated in the further survey programs ordered by the Belgian Authorities as a substitute for the classic bathymetric vessel soundings.
WIND SPECIFICATION FOR SPECTRAL OCEAN-WAVE MODELS
Authors: Khandekar M.L. , Eid B.M.
Published: June 2019

This paper investigates the utility of winds obtainable from a numerical weather prediction model for driving a spectral ocean-wave model in an operational mode. Wind inputs for two operational spectral wave models were analyzed with respect to observed winds at three locations in the Canadian east coast offshore. Also, significant wave heights obtainable from the two spectral models were evaluated against measured wave data at these locations. Based on this analysis, the importance of appropriate wind specification for operational wave analysis and forecasting is demonstrated.
EFFECTS OF THE GULF STREAM ON NEARSHORE WAVE CLIMATE
Authors: Lai R.J. , Bales S.L.
Published: June 2019

Large scale ocean currents, such as the Gulf Stream, Kuroshlo, Peru Current, Agulhaus Current, etc., strongly modify the surrounding wave characteristics. As the Gulf Stream moves along the Continental Shelf of the southeast coast of the United States, the local ocean environment is divided into three wave climatic regimes. They are the offshore, the Gulf Stream, and the nearshore regimes. The nearshore zone is bounded by the land to the west and the Gulf Stream to the east. The distance between land and the Gulf Stream varies from 10 to 60 miles. Most of the waves in this regime are generated offshore and cross the Gulf Stream. The correlation of local wind and waves in the nearshore regime is poor except in the presence of a persistent onshore storm. A semi-empirical approach has been developed to compute the nearshore wave climate. The hindcast/forecast directional waves from the Spectral Ocean Wave Model (SOWM) of the Navy Fleet Numerical Oceanography Center have been used as the source of the initial offshore wave conditions. After crossing the Gulf Stream, which is assumed to be a uniform current with a velocity of 2 m/s, the waves are either refracted to the nearshore regime or reflected to the offshore regime following ray theory. The onshore waves in the nearshore zone are confined to the sector from 30 to 150 degrees. The computed results are then compared with measured data with good agreement. In summary, the Gulf Stream acts as a barrier to damp long waves and to regroup short waves. The refraction of long waves can be predicted by using ray theory. Further field experiments are needed to quantify the variation of the Gulf Stream and to investigate the interaction with approaching long waves and local wind generated short waves.
EMPIRICAL PREDICTION OF WAVE SPECTRUM FOR WIND-GENERATED GRAVITY WAVES
Authors: Lin Jung-Tai
Published: June 2019

Wind-Generated gravity wave has been of great interest to researchers and engineers in the field of coastal engineering because it is one of the important considerations in the engineering studies and designs for ship navigation, coastal and off-shore structures, shore protection, oil pollution control, and wave energy conversion. An accurate prediction of the wave height, wave frequency, and wave spectrum is critical to the success of these engineering studies and design.
ESTIMATING LONG-TERM WAVE STATISTICS FROM LONG-TERM WIND STATISTICS
Authors: Liu Paul C.
Published: June 2019

The Wave Climate Synthesis method, which derives long-term wave statistics from long-term wind statistics directly, is tested with four years of wind and wave measurements recorded from eight NOMAD buoys in the Great Lakes during 1981-1984. The results show that it is an excellent method for estimating long-term wave statistics and design wave height. While the method is by no means intended to replace wave hindcasting procedures, it is shown to be a useful additional tool for the coastal engineer.
FERRY WAVE MEASUREMENTS IN DEEP WATER
Authors: Nece Ronald E. , McCaslin Michael R. , Christensen Derald R. , Yeh Harry H.
Published: June 2019

Data are presented for ship waves generated and measured in deep water. Results show the variation of maximum vessel waves with both vessel speed and distance from the vessel sailing line. Three automobile ferries of different configurations were tested. Field test procedures, limitations, and problems are described.
ESTIMATION OF EXTREME SEA SEVERITY FROM MEASURED DAILY MAXIMA
Authors: Ochi Michel K. , Mesa David , Liu De-Fu
Published: June 2019

This paper presents the results of a study to statistically estimate the most severe sea state (significant wave height) expected in 50 and 100 years from analysis of data consisting of the largest significant wave height observed each day by applying the Type III asymptotic extreme value distribution. In applying the Type III asymptotic distribution, the distribution parameters are estimated by three different methods: the maximum likelihood method, the skewness method, and a nonlinear regression method. Since none of these methods estimates values of the parameters which satisfactorily yield a distribution representing well the daily maximum data, a modified Type III asymptotic distribution is newly developed in the present study. The modified distribution yields an excellent fit over the entire range of the cumulative distribution, and the probability density function agrees well with the histogram constructed from the data.
BIPERIODIC WAVES IN SHALLOW WATER
Authors: Scheffner Norman W.
Published: June 2019

The propagation of waves in shallow water is a phenomenon of significant practical importance. The ability to realistically predict the complex wave characteristics occurring in shallow water regions has always been an engineering goal which would make the development of solutions to practical engineering problems a reality. The difficulty in making such predictions stems from the fact that the equations governing the complex three-dimensional flow regime can not be solved without linearizing the problem. The linear equations are solvable; however, their solutions do not reflect the nonlinear features of naturally occurring waves. A recent advance (1984) in nonlinear mathematics has resulted in an explicit solution to a nonlinear equation relevant to water waves in shallow water. This solution possesses features found in observed nonlinear three-dimensional wave fields. The nonlinear mathematical formulation referred to above has never been compared with actual waves, so that its practical value is unknown. The purpose of the present investigation was to physically generate three-dimensional nonlinear waves and compare these with exact mathematical solutions. The goals were successfully completed by first generating the necessary wave patterns with the new U.S. Army Engineer Waterways Experiment Station, Coastal Engineering Research Center's (CERC) directional spectral wave generation facility. The theoretical solutions were then formed through the determination of a unique correspondence between the free parameters of the solution and the physical characteristics of the generated wave.
TROPICAL CYCLONE GENERATED CURRENTS
Authors: Sheng Y. Peter , Chiu Sherman S.
Published: June 2019

AXCP data obtained during Hurricane Josephine in 1984 are analyzed in this paper. In addition, wind-driven currents at several XCP's during Josephine are simulated using a one-dimensional ocean current model.
COMPLEX ENVELOPE IDENTIFICATION OF WAVE GROUPS
Authors: Sobey Rodney J. , Liang Han-Bin
Published: June 2019

The complex envelope function is presented as the natural analysis technique for wave records where the identification of wave groups is a dominant interest. Algorithms have been developed and confirmed for separation of the complex envelope function, estimation of the dominant frequency and unwrapping of the phase function. Cross-correlograms and coherence spectra reveal a link between the envelope amplitude and phase traces that appears to be an intrinsic property of wave groups. Nevertheless, the majority of the information in typical wave records can be described as random, accounting for the relative success of the Gaussian random wave model.
SHOALING AND REFLECTION OF NONLINEAR SHALLOW WATER WAVES
Authors: Vengayil Padmaraj , Kirby James T.
Published: June 2019

The formulation for shallow water wave shoaling and refraction diffraction given by Liu et al (1985) is extended to include reflected waves. The model is given in the form of coupled K-P equations for forward and backward propagation. Shoaling on a plane beach is studied using the forward-propagating model alone. Non-resonant reflection of a solitary wave from a slope and resonant reflection of periodic waves by sinusoidal bars are then studied.
WAVE BASIN EXPERIMENTS ON BOTTOM FRICTION DUE TO CURRENT AND WAVES
Authors: Visser Paul J.
Published: June 2019

Results are presented of experiments in a wave basin on the increase of the mean bottom frictional stress in a flow when a wave field is superimposed on a current. The bottom friction was derived from the mean water level measured at various places. Measurements of wave orbital and mean current velocities were done both with a micro-propeller and with a new type immersible Laser Doppler Anemometer. The data indicate an increase of the mean bottom shear stress due to the presence of the waves, but less than predicted by Bijker (1967). A suggestion is made to improve the accuracy of this theory. The bottom stresses as predicted by Fredsoe (1984) are somewhat larger than the, experimental results.
MAGNITUDE OF THE B-FACTOR UNDER WAVE ACTION
Authors: Van de Graaff J. , Steijn R.C.
Published: June 2019

The sediment transport due to waves and currents depends on the distribution of sediment concentration and on the distribution of the velocity over the water depth. Our knowledge of both phenomena for practical applications is still rather poor. Some results of wave flume tests concerning the distribution of sediment concentrations due to wave action will be discussed. It turns out that the sediment size of the bottom material has a rather unexpected effect hereupon. With respect to the velocity distribution only some qualitative remarks can be made at the moment.
CHANGES IN CURRENT PROPERTIES DUE TO WAVE SUPERIMPOSING
Authors: Asano Toshiyuki , Nakagawa Masahiro , Iwagaki Yuichi
Published: June 2019

Changes in current properties due to wave superimposing are investigated experimentally. Variations of the mean water level gradient and the current velocity profile after wave superimposing are examined. Experimental results are discussed in relation to the energy conservation equation including the bottom friction term. It is found that changes in current properties can be well explained by increase in the time averaged bottom shear stress.
A NUMERICAL INVESTIGATION OF THE LONGSHORE CURRENT PROFILE FOR MULTIPLE BAR/TROUGH BEACHES
Authors: Baum Steven K. , Basco David R.
Published: June 2019

A numerical model is developed which calculates the longshore current profile for an arbitrary bottom profile. The basis of the model is the use of radiation stress theory in a longshore momentum balance equation which includes a driving stress, a bottom stress, and a lateral mixing stress. Each of the stresses is derived from previously developed formulations, rederiving them to take into account separate cross shore variations in the wave height and the water depth, as well as the wave approach angle. This is done to dispense with the constant wave breaking index assumption used to model wave decay in the surf zone, which is rejected as unrealistic for natural beaches. A numerical model is used to calculate distributions of the wave height and water depth across the surf zone for arbitrary, yet realistic, bottom profiles. A numerical model of the theoretically derived longshore momentum balance equation is developed and solved using the distributions obtained from the wave decay model. The profiles calculated are compared to previous theoretical models and to laboratory and field measurements.
VELOCITY AND SEDIMENT CONCENTRATION FIELDS ACROSS SURF ZONES
Authors: Dette Hans H. , Uliczka Klemens
Published: June 2019

Wave-induced currents and sediment concentrations in suspension across the surf zone were investigated at prototype scale in the BIG WAVE FLUME in Hannover for combined beach and dune profiles as well during the development phase until quasi-equilibrium stage as after beach equilibrium conditions had been reached. The selected initial profiles were partly investigated in repeated tests with regular and irregular waves. Based upon the obtained experimental data a comparison is presented between the measured and calculated landward displacement of sediment volume through a selected point on the beach into seaward areas. The discrepancies in between the results for measured profile change and for calculated sediment transport volume derived from vertical current and suspension distributions are discussed.
DIRECTIONAL NEARSHORE WAVE PROPAGATION AND INDUCED CURRENTS
Authors: Dingemans M.W. , Stive M.J.F. , Bosma J. , De Vriend H.J. , Vogel J.A.
Published: June 2019

Recently, a depth and current refraction model has been developed for the computation of directionally spread, random wave propagation in coastal regions (Booij et al., 1985). For the verification of the performance of this model laboratory measurements in a directional, shallow water wave basin were conducted. Specific attention was given to the verification of the new features of the numerical model, viz. the effects of directional spreading and ambient current field on the wave propagation and transformation process, and the change of characteristic spectral wave frequency due to wave dissipation processes.
EVALUATION OF MODELS OF NEARSHORE PROCESSES
Authors: Fleming C.A. , Pinchin B.M. , Nairn R.B.
Published: June 2019

The Canadian Coastal Sediment Study, known as C2S2, included numerous activities related to improving the measurement and prediction of sand transport in the nearshore zone. The data was used to evaluate a number of predictive techniques commonly used for coastal zone modelling for both alongshore and onshore/offshore sediment transport modelling. Field experiments were carried out at two sites. This paper is concerned with the first of these sites at Pointe Sapin, New Brunswick. Computed transport rates were compared with volumes of sand that accumulated in a sand trap formed by an offshore breakwater upstream of the mouth of Pointe Sapin harbour. The predictive techniques used were a parametric wave hindcasting model, a spectral wave refraction model, alongshore current predictors, seven of which rely on computed alongshore current distributions.
EXPERIMENTAL INVESTIGATION OF THE WAVE AND CURRENT MOTION OVER A LONGSHORE BAR
Authors: Hansen J. Buhr , Svendsen Ib. A.
Published: June 2019

The results presented in this paper are from a series of experiments in a wave flume modelling the onshore-offshore water motions over a bar bottom profile. In a true 3-dimensional natural situation the flow of water over the bar varies along the coast. In the experiments the flow of water over the bar is simulated by a controlled discharge through the flume.
THE BOTTLENECK PROBLEM FOR TURBULENCE IN RELATION TO SUSPENDED SEDIMENT IN THE SURF ZONE
Authors: Justensen Peter , Fredsoe Jorgen , Deigaard Rolf
Published: June 2019

In the present paper the vertical distribution of turbulent kinetic energy k under broken waves is calculated by application of a one-equation turbulence model. The contributions to the energy level originate partly from the production in the wave boundary layer, partly from the production in the roller. Further on, the findings for k are used to calculate the vertical distribution of suspended sediment in broken waves.
LOCAL MOVEMENTS OF SAND IN THE SURF ZONE
Authors: Katoh Kazumasa , Tanaka Norio
Published: June 2019

The fluorescent sand tracers are injected in a point in the surf zone. Core samples are taken from the sixteen points on the circumference with the time intervals of fifteen minutes for about five hours. At the same time, the horizontal two components of fluid velocities are measured at the injection point by using an electromagnetic currentmeter. The field observations have been carried out three times on two beaches facing to the Pacific Ocean. The relations between the local sand movements and the fluid dynamics are examined on the basis of the data obtained.
APPLICABILITY OF SUB-SAND SYSTEM TO BEACH EROSION CONTROL
Authors: Kawata Yoshiaki , Tsuchiya Yoshito
Published: June 2019

We performed experiments in the laboratory under controlled conditions in order to determine the applicability of a sub-sand filter system to the beach erosion control work. The filter system is used to control a flow condition at the sediment-fluid boundary. In the foreshore, it increases the inflowing velocity into the beach and thus results in increasing the threshold of beach sediment movement. The sub-sand filter system accelerates accretion of much beach sediment in the foreshore through the development of a berm under normal wave conditions. When wave conditions change from normal to stormy , it is also applicable to stabilize the beach profile, and thus decrease loss of beach sediment from the foreshore to the offshore.
UNDISTORTED FROUDE MODEL FOR SURF ZONE SEDIMENT TRANSPORT
Authors: Kriebel D.L. , Dally W.R. , Dean R.G.
Published: June 2019

Small scale movable bed wave tank experiments were carried out according to undistorted Froude model laws with the sediment fall time, H/wT, as the governing parameter for scaling the model sediment. Four questions addressed in this study included: (a) the ability to reproduce larger scale model results for both erosional and accretive conditions, (b) the effects of more realistic concave upward initial beach profiles instead of the more usual planar initial slopes, (c) the criterion for onshore-offshore sediment transport, and (d) the capability of the model to simulate post-storm recovery. Based on a comparison with large scale results of Saville (1957), it was found that the model provided good agreement for erosive conditions. For accretive conditions, the results were less conclusive although the general patterns of profile change were similar. The final beach profiles resulting from concave upward initial profiles were found to be substantially different from those for an initially planar profile. It appears that the initially planar profile unrealistically affects the breaker type and results in a more pronounced longshore bar and offshore slopes that are steeper than found in nature. Tests conducted to evaluate the criterion separating onshore-offshore transport suggested a higher value of the fall time parameter, H/wT, than was originally proposed by Dean (1973); this is interpreted to be due to scale effects in most of the model data used in the original development. Tests to simulate post-storm recovery were affected by the presence of "reflection bars" associated with a partial standing wave system. The reflection bars appear to strongly affect the sediment transport limiting the post-storm profile recovery. The most effective recovery was induced by continually changing wave conditions to maintain the wave breakpoint slightly landward of the bar crest.
EXPERIMENTAL STUDY ON ON-OFFSHORE SEDIMENT TRANSPORT OF ACCRETIVE BEACH
Authors: Kuo Ching-Ton , Hwang Ching-Her , Tseng I-Chou
Published: June 2019

In treating coastal proceses, sediment transport is usually divided into along-shore and on-offshore components. It is believed that the on-offshore component has a prominant connection with short-term profile changes, observed during storm wave climates. Obviously its shift of sand plays a very vital role in shoreline migration. In other words, the beach profile has great bearing on coastal phenomena related to on-offshore sediment transport. As we know, there have been many studies on this kind of sediment transport rate, and considerable amount of knowledge on this problem has been accumulated so far. Yet it seems that we are still far from a reliable formulus to estimate the beach profile changes. The reason why is due to the complexity of mechanics of sediment transport. Therefore, the aim of this study is to examine experimentally the mechanism between onoffshore sediment transport and the deformation processes of twodimensional beach profile. Then , a predictive model of the temporal and spatial distribution of net on-offshore sediment transport based on two-dimensional beach profiles and an equation of continuity of sediment transport is proposed. Various parameters of net on-offshore sediment transport in this model are discussed also.
NUMERICAL MODEL OF BREAKING WAVE AROUND A RIVER MOUTH
Authors: Lee Jong-Sup , Sawaragi Toru , Deguchi Ichiro
Published: June 2019

Equations for wave kinematics and wave dynamics based on small amplitude wave theory have been used in the prediction of wave deformations and wave-indused currents. However, the applicability of the linear wave theory is questionable in a river mouth where forced wave breaking and strong wave-current interaction take place. A numerical model based on the non-linear dispersive wave theory has been developed, the results by this model was compared with the values of the experiments and the linear theory. Wave transformations including shoaling, wave-current interaction and wave breaking by the model showed a good agreement with the experimental result. In the prediction of wave-induced currents, the excess momentum flux (Pxx) computed by the model has more reasonable value than the radiation stress ( Sxx) calculated by the small amplitude wave theory.
TRACERS OF SAND MOVEMENT ON THE OREGON COAST
Authors: Clemens Karen E. , Komar Paul D.
Published: June 2019

The study of sand mineralogy and grain rounding can help answer many questions of immediate concern to coastal engineers or to broader issues of beach preservation. The heavy-mineral contents of sands, together with statistical techniques such as factor analysis, can be used to delineate sediment sources, trace transport paths, and map out patterns of mixing during sediment dispersal. Variations in the degree of grain rounding can similarly be used to trace sand movements, or to obtain additional information concerning the history of the sediment particles. The techniques of studying sand mineralogies and grain rounding, and the types of problems they can address, are illustrated by research on the Oregon coast. Heavy mineral compositions of Oregon beach sands are the products of mixing contributions from four sources; the Columbia River on the north, the smaller rivers draining the Coast Range, the Umpqua River on the southern Oregon coast, and the Klamath Mountains of southern Oregon and northern California. Numerous headlands now prevent the longshore transport and mixing of sands from these multiple sources. The beach-sand compositions instead reflect along-coast mixing during Pleistocene lowered sea levels when blockage by headlands was absent. At that time there was a net littoral sand transport to the north, evident from the dispersal of Klamath-derived sands. With a rise in sea level and accompanying migrations of the beaches, headlands eventually interrupted the along-coast mixing of nearshore sands. Therefore, the north to south variation in compositions of beach sands is in part a relict pattern inherited from mixing during lowered sea levels. This has been modified during the past several thousand years by some additions of sand to the beaches from sea-cliff erosion and from rivers. However, studies of sediment mineralogy and grain rounding indicate that sands derived from most rivers draining the Coast Range are presently trapped in estuaries and so are not significant sources of beach sand. The Columbia River now supplies sand to Oregon beaches only to the first headland, Tillamook Head. At that headland there is a marked change in mineralogy and grain rounding with angular, recently supplied Columbia River sand to the north and rounded relict sand to the south.
PROBABILISTIC ANALYSIS OP SEAFLOOR LIQUEFACTION
Authors: Blazquez Rafael , Martinez Felipe M.
Published: June 2019

To investigate the reliability of a sandy soil layer in an ocean wave environment a liquefaction model is used in conjunction with a first order reliability method. Thus, sensitivity indices of the soil-water system with respect to the uncertain strength and input variables are computed, and the relative importance of the various factors defining the problem can be determined. The relationship of this approach with more conventional design methods (deterministic models, risk models) is discussed along with the range of applicability of the different safety measurements.
LONGSHORE CURRENT AND TRANSPORT ACROSS NON-SINGULAR EQUILIBRIUM BEACH PROFILES
Authors: Bodge Kevin R.
Published: June 2019

The longshore current and longshore sediment transport distributions are described across an equilibrium beach profile comprised of an intersecting planar foreshore and a concave-up profile. Such a profile shape avoids the singularity associated with the infinite-slope at the shoreline described by traditional equilibrium profile forms and allows prediction of beach processes at and above the shoreline. The mathematical expressions which describe the distributions are simplified and can be more readily applied relative to expressions previously presented in the literature. The findings are in general agreement with similar previous analytic studies and indicate that the current and transport maxima are generally located at about the intersection of the planar and concave-up portions of the profile.
DUNE EROSION AND SEDIMENT PROFILE DUE TO WAVE UPRUSH
Authors: Fenaish T.A. , Overton M.F. , Fisher J.S.
Published: June 2019

Shorelines are continuously adjusting in response to the changing hydraulic and meteorological conditions. Storms that generate large waves and surge conditions can alter the nearshore topography and relocate the beach shorelines, often with substantial amounts of beach and dune erosion. Such storms pose a major threat to coastal developments for which the economic impact can be significant. The ability to predict the rate of erosion and, consequently the shoreline change, is important in making decisions regarding the planning and managing of the coastal regions. In general, the available methods for the prediction of beach and dune erosion are based on the assumption of post-storm equilibrium profile. In this approach it is assumed that, for a given set of wave and surge conditions, the entire beach reaches a steadystate, and that the volume of sand released from the dune is equal to the volume of sand required to establish this profile. Existing methods that are based on this concept include those developed by Edelman (1968, 1972), Vellinga (1982, 1983, 1986), Kriebel and Dean (1984), Sargent and Birkemeier (1985), and Kobayashi (1987).. The reliance of these methods on the assumption of steady-state condition limits their application to extreme events generated by severe storms. Generally, storms do not have sufficient duration or intensity, such that the beach profile attains equilibrium during the storm.