bluuebunny/crossref_metadata_2025 huggingface dataset:
VISIBLE-REGION PHOTOGRAPHIC REMOTE SENSING OF NEARSHORE WATERS
Authors: Sunamura Tsuguo , Horikawa Kiyoshi
Published: June 2019

By use of a synchronized camera system, multiband black and white photographs and conventional color photographs were taken respectively with the purposes of testing filters available for shallow-water photographic bathymetry, and of checking the availability of low-cost process imagery for the study of coastal processes. Kodak Wratten filters 29, 58, and 90 were employed for the multiband photography. A Wratten 90 filter provided the best correlation between water depth and the photographic density. The low-cost imagery, obtained in a laboratory from the color photographs by applying ordinary filters without using any expensive image processing devices, proved to be useful.
ONSHORE-OFFSHORE SEDIMENT MOVEMENT ON A BEACH
Authors: Nielsen P. , Svensen I.A. , Staub C.
Published: June 2019

A theoretical model is developed for the movement of loose sediments in oscillatory flow with or without a net current. In the present formulation the model is two-dimensional, but may readily be extended to three dimensions. It is assumed that all movement of sediments occurs in suspension, and exact analytical solutions are given for the time variation of the concentration profile, the instantaneous sediment flux and the net flux of sediment over a wave period. The model requires as empirical input a diffusion coefficient e and pick-up function p(t), for which experimental data are presented. Two examples are discussed in detail, illustrating important aspects of the onshore-offshore sediment motion.
SCALE RELATIONS FOR EQUILIBRIUM BEACH PROFILES
Authors: Noda Hideaki
Published: June 2019

There are many practical problems related to coastal engineering, which may be solved by using movable bed scale models of the coastal zone. The scale model must obey the laws of sediment transport in order to obtain satisfactory results. However, sediment transport in the coastal zones is so complex that the mechanism is not fully understood. Some authors have attempted to find a model law relationship for equilibrium beach profiles. Yalin-'-^ derived a scale law for the offshore zone using a bed velocity based on laminar boundary conditions. Brebner, Karaphuis and Paul^' have performed extensive experimental tests on movable-bed models using light weight sediment, and Le Mehaute^) presented a scaling law for coastal movable-bed models in the breaker zones. The purpose of this study is finally to determine the scale law relationship for coastal movable-bed model. As first step, this paper concerns itself with the derivation of proper scale laws for modeling of equilibrium beaches.
A COMPARISON BETWEEN DREDGE INDUCED SEDIMENT RESUSPENSION AND THAT PRODUCED BY NATURAL STORM EVENTS
Authors: Bohlen W. Frank
Published: June 2019

Field observations indicate that the effect of dredge-induced resuspension on sediment transport within small estuaries is generally negligible in comparison to the transport induced by natural storm events. Data obtained in the Thames River, near New London, Connecticut show dredge-induced resuspension to be essentially a near field phenomenon. The resultant plume of material increases total suspended load in the river by approximately 25% but extends over less than 2.5% of the total estuarine area. In contrast storms are observed to increase total suspended load by a factor of three, influencing concentration levels throughout the estuary. These factors, in combination with the lower frequency of dredging vis-a-vis significant storm events, appear to effectively limit the influence of dredge-induced resuspension.
WAVES FORCES ON OFFSHORE PIPELINES
Authors: Jothishankar N. , Sundar V.
Published: June 2019

Transportation of offshore oil and gas is mostly carried out by means of offshore pipelines. Depending on the ocean environment these pipelines are either buried or made to rest on the ocean bed or placed on excavated trenches. In cases where the sea bed is mostly of rock, pipelines can be laid on the bed and anchored to the ocean floor by suitable supports. In certain instances pipelines are also placed on saddles leaving a clearance between pipe and the sea floor. The design of these pipelines requires an accurate assessment of wave induced loads acting on them. The objective of this paper is to present the experimental results of wave forces exerted on a model pipeline, of diameter 5 cms at different clearances from the bed of the flume. Hydrodynamic coefficients namely Drag and Inertia are computed from the measured forces and their correlation with the non-dimensional parameters, Reynold's Number, Keulegan-Carpenter Number and relative clearance from the bed are presented.
DESIGN OF AN OVERTOPPING BREAKWATER
Authors: Treloar P.D. , Nagle B.
Published: June 2019

The Maritime Services Board of New South Wales, Australia, is constructing a major new port facility on the northern foreshores of Botany Bay. A principal part of this project has been the construction of a large armoured revetment from the northern shores. The entrance to Botany Bay faces southeast and it is from this direction that a large proportion of offshore wave energy arrives. Some of the wave energy which is directed onto the Bumborah Point revetment is reflected towards Yarra Bay on the northern shores of Botany Bay. Yarra Bay is largely undeveloped, but a sailing club has stood for many years on the beach at the southern end. As a consequence of this reflected wave energy being directed towards Yarra Bay, its wave climate has been changed considerably so that during the storms of May-June, 1974, Foster (6), damage was suffered by the club-house. Additionally the more severe wave climate and consequent steeper beach have made it much more difficult to launch sailing boats. The Maritime Services Board is charged with the responsibility to carry out remedial works where damage is caused by the port development. Figure 1 shows the revetment and sailing club site. To assist in coastal engineering design aspects of the port development, a large fixed bed wave model of Botany Bay has been built to an undistorted scale of 1:120. This model, some aspects of which have been described by Lawson (4), has pneumatic wave generators which enable offshore wave directions between east-north-east and south to be generated with prototype periods in the range of 5 to 16 seconds. A pneumatic tide generator enables a sinusoidal tide to be generated.
DOLOSSE PAST, PRESENT, FUT
Authors: Zwamborn J.A. , Bosman D.E. , Moes J.
Published: June 2019

Information is presented on 38 dolos projects in various parts of the world. Some of the data were collected by means of questionnaires and the remainder are based on publications, reports and personal visits. Information is given on design conditions, structure details, model tests and site experiences. Past dolos research is discussed briefly. Present experience of damage to various dolos structures is described, particularly that to the 2 km long Sines main breakwater. The results are discussed of research initiated by differences in accepted design and model test conditions and the recent dolos failures. This research concerned dolos packing densities, dolos movements (damage criteria) and structural failure of armour units. There is little doubt that dolosse will be used effectively and economically, in the future for many small and medium-sized coastal structures. However, special attention will have to be given to deep-water structures of any kind, with regard to representative design conditions, the effect of the larger waves in the spectrum and the possibility of structural failure of armour units. A few practical suggestions are made for the design of safer dolosse, in the interim, but it is recommended that a major effort be made to collect reliable data on existing structures as well as to develop representative and, preferably, standardized design and model test techniques.
WAVE HEIGHT DISTRIBUTION AROUND PERMEABLE BREAKWATERS
Authors: Hotta Shintaro
Published: June 2019

A phase lag phenomenon in which waves are delayed in transmission through a permeable breakwater was considered in an approximate calculation method using the superposition principle of Sommerfeld. Experimental verifications were carried out for a semi-infinite permeable breakwater. In addition, a field observation of wave height distribution around a small detached breakwater is reported.
STABILITY OF RUBBLE MOUND BREAKWATER
Authors: Feuillet J. , Sabaton M.
Published: June 2019

The stability of a rubble mound breakwater section, with 3 in 2 armour slope, was tested under random waves attack. Tests analysis shows that the equivalent wave height characterizing the spectrum to be used in a stability formula elaborated with regular waves (for instance the Hudson's formula) is the upper twentieth height of the distribution for a storm duration of 6 hours. An analytical expression of the damage evolution as function of time modulates this choice according to the storm duration. The same rubble mound breakwater was also tested under the action of regular breaking waves. The damage was expressed in terms of the four following parameters : H0 : wave height T : wave period Dp : water depth at the toe of the structure Djj : breaker depth without the breakwater For a given wave height, the most important damage occur when : °b In this case the design wave height must be increased by about 30 % when using a stability formula elaborated for non breaking waves.
ARTIFICIAL RESORT BEACH PROTECTED BY OFFSHORE BREAKWATERS AND GROINS
Authors: Sato Shoji , Tanaka Norio
Published: June 2019

In Japan, area of natural beaches has decreased in the vicinity of cities, towns and villages, in consequence of constructing ports and harbours, reclamating shore and beach, and building strom-surge prevention structures like sea dikes and sea walls. On the other hand, the demand of people for recreation area is increasing year by year with the improvement of living and economic conditions. Therefore, since several years ago, local governments have extensively been constructing artificial beaches and restoring eroded beaches on many places by the aid of the central government. Such artificial beaches, however, need large amount of natural sand, in spite of the deterioration of sand supply and the soaring of sand price. Moreover, local governments are able to get subsidiary payments of the central government for the construction of artificial sand beach, but not for replenishing sand lost by wave action after the completion of the construction works. Therefore, most artificial beaches in Japan are usually protected by groins and offshore breakwaters in order to retain artificially filled sand. But in summer when sea is in calm condition, pollutant produced by sea-bathing people or discharged from the land is likely to stagnate in the vicinity of the shoreline on account of such structures. From the above-mentioned, coastal engineering problems on construction and restoration of sand beach in Japan are: (1) suitable arrangement of offshore breakwaters and groins from standpoint of artificial beach protection (2) keeping the sea water of the beach clean (3) estimation of profile change of the artificial beach due to wave action after its construction. This paper presents the results of investigations conducted with the aim of solving the above coastal engineering problems related to artificial beach constructions at Suma and Ito beaches. The investigations are mainly conducted using model experiment.
THE EFFECTS OF CONSTRUCTION TECHNIQUES & BULK TERMINAL OPERATIONAL REQUIREMENTS ON THE DESIGN CRITERIA FOR ISLAND BREAKWATERS
Authors: Eooie A.G.F. , Lawson J.O. , Graze H.R. , Dean B.K.
Published: June 2019

The title of the paper contains two important key words - CONSTRUCTION and ISLAND. The techniques for safe and economical construction of an island breakwater located some distance from the shore in exposed waters are radically different from the techniques required for conventional breakwaters with one end attached to the land. The differences in construction technique are so profound as to change the preferred basic design selection from rubble mound to caissons. The paper discusses:- 1. The circumstances in which island breakwaters will become increasingly necessary for unloading of bulk ships. 2. Reasons why prefabricated caisson breakwaters are preferable for construction in an offshore situation. 3. The economy to be gained by using the caissons as the structural support for ship unloading machinery. 4. A consequent necessity to develop a caisson breakwater configuration with adequate design criteria to ensure total safety of the equipment supported on it. 5. A research program aimed at deriving these criteria.
THE DESIGN AMD CONSTRUCTION OF THE NEW OIL PORT IN DALIAN, C.P.R.
Authors: Zhuang Zhu
Published: June 2019

The construction of New Oil Port in Dalian, C.P.R., was started around the end 1974 and completed in autumn 1976.In this paper a summary of the essential considerations in design and construction of this oil port, such as the planning of the pier, the determination of exciting forces (namely wave forces, forces due to earthquake, mooring line forces and berthing forces due to the impact of tanker on the fenders)on structures, the design of the large cylindrical cassion with a diameter of 9m and a height up to 19.7m and the construction of connecting bridges by two types, is presented.
SEPARATION OF CLIMATIC FLUCTUATIONS AND IMPACTS OF ENGINEERING ACTIVITIES IN ESTUARIES
Authors: Krause G.
Published: June 2019

Using salinity as an example of dissolved substances in estuarine waters it is shown how the long term trend of concentrations can be split up into a man-made and a climatic contribution. The understanding of long term mixing processes and adequate sampling techniques are essential for this purpose. The physical state of the estuary can be described in terms of 3 basic variables, the river discharge, the filtered water level and the filtered salinity. The river discharge represents the climatic fluctuations in the catchment area, and the filtered water level is a record of the large scale weather pattern over the adjacent ocean basin. Salinity trends which cannot be attributed to these two variables must originate from man-made actions, such as dredging or other engineering activities which change the geometry of an estuary. Two models are used for the trend analysis, the simplest possible mixing equation (which always holds for a sufficiently long time scale), and a salt flux consideration.
HYDRAULIC RESEARCH IN THE OOSTERSCHELDE ESTUARY
Authors: Walther A.W.
Published: June 2019

In 1974 a major policy change was made to the Delta plan (fig. 1) to close the Oosterschelde (East Scheldt). For ecological reasons it was decided to replace the originally planned barrier dam with a storm surge barrier. This could be opened to allow normal tidal movement or closed during storm surges.
ARTIFICIAL ROUGHNESS IN PHYSICAL MODELS OF ESTUARIES FOR STORM SURGE INVESTIGATIONS
Authors: Berndt D. , Giese E. , Schwarze H. , Vollmers H.J.
Published: June 2019

One of the characteristics of the North Sea between the British Isles, the Netherlands, Germany and Denmark is the occurrence of heave storm surges especially in autumn and winter with heights of about 4 m above spring highwater. Coastal areas and especially the estuaries of the tidal rivers are hit by these storm surge events. The mean tidal range at the German coast comes to about 3 m with relatively low daily and semimonthly inequalities of less than 0.5m. Within the framework of long-term developments of the navigation channels of the estuaries as well as of the storm surge protection works, physical model tests had to be carried out in order to predict the influences of such measures on the storm surge heights to be expected.
AN HEURISTIC MODEL OF WAVE HEIGHT DISTRIBUTION IN SURF ZONE
Authors: Mizuguchi Masaru
Published: June 2019

Until now, almost every study on coastal processes has considered the basic type of two-dimensional beach profile as being of constant slope. However, as our knowledge on this problem advances, we realize the importance of the influences of the bottom configuration on the hydrodynamic phenomena in a given area. Figure 1 shows a recent experimental result on the longshore current profile on a step type beach. ( Here the step type beaches are defined as those which have a step in the bottom profile, whether the beaches are of accretion type or not.)
THE CORPS OF ENGINEER'S GENERAL INVESTIGATION OF TIDAL INLETS
Authors: Sorensen Robert M.
Published: June 2019

During the past decade the U.S. Army Corps of Engineers has been conducting a General Investigation of Tidal Inlets (GITl). The GITI was an applied research program through which a wide range of inlet phenomena relating to Corps responsibilities for coastal navigation and recreation, prevention of beach erosion, and control of coastal flooding were investigated. The program was managed by the U.S. Army Coastal Engineering Research Center (CERC); specific research projects were conducted by CERC, the U.S. Army Waterways Experiment Station (WES), private consultants, and universities. The various GITI research efforts can be divided into five categories: 1) field studies of the hydraulics and sedimentary dynamics of selected inlets, 2) analysis of historic field data, 3) numerical models of inlet hydraulics, 4) movable and fixed-bed physical inlet models, and 5) other miscellaneous inlet studies. Research results are being published in a special report series. The number, title, author and date of each report are listed in the Appendix - GITI Reports. The intent of this paper is to summarize GITI research efforts and, based on key results of this research as well as recent Corps field experience, to recommend new areas for research.
BOUNDARY CONDITIONS FOR ANALYSIS OF FLOW IN TIDAL INLETS
Authors: Copalakrishnan T.C. , Machemehi J.L.
Published: June 2019

One-dimensional gradually varied flow analysis of flood routing and inlet flows (Mahmood and Yevjevich, 1975; Amein, 1975 and Hinwood and Wallis, 1975) has been a subject of study in the last few decades and many mathematical models have been developed based on those studies. A common feature in all these models is that the boundary conditions at the ends of the channel reaches are supplied from measured values of stage, discharge or velocity. These boundary conditions form an integral part of the mathematical models. In the case of implicit schemes, without the supply of these boundary conditions there will be more unknowns than equations. Even though in the explicit schemes they are not required in order to supply sufficient equations, it is obvious that the flow will not be properly simulated without imposing proper end conditions of flow. Normally two end conditions will be required, the upstream and downstream conditions, even though in a network of channels there will be more than two end conditions. Of these two the upstream condition is usually the forcing function and the downstream one is the result of the flow due to the forcing function. The downstream condition depends on what happens to the flow outside the system. In other words, it depends on the shallow water wave reflections from the continuation of the channel beyond the downstream end of the system considered. These reflections are characterized by the expansion or contraction of the channel, the rate of change of the side slopes and other channel characteristics. As mentioned earlier, the downstream end condition is supplied from measured values of flow parameters so that the channel features (outside the system) mentioned above are automatically simulated. However, if it is required to know the response for any given forcing function, the corresponding measured downstream values may not be available. This means that the downstream boundary condition cannot be imposed in ,the usual way. This paper describes a method by which the downstream boundary condition can be imposed in the absence of measured downstream response to a given forcing function.
BARDEN INLET, N.C. A CASE STUDY OF INLET MIGRATION
Authors: Vallianos Limberios
Published: June 2019

The migratory pattern of a small coastal inlet was examined in terms of the factors generally acknowledged to control inlet behavior. That is, the tidal discharge which acts to flush the inlet and, on the other hand, the intrusive littoral materials depositing in the inlet environment. Specifically, a "flow conveyance index" was computed and compared to shoreline movements. The "flow conveyance index" was defined as the ratio of the mean distribution of the overall planform area of the throat of the inlet to the mean distribution of the planform areas of shoals within the throat of the inlet. High and low "flow conveyance index" values would correspond, respectively, to periods of relatively high and low inlet flushing conditions. A consistent pattern obtained from this analysis, wherein high and low index values corresponded with high and low shoreline movements. Additionally, the plot of rates of shore movements against rates of change of "flow conveyance index" was fitted with a simple linear regression line having a positive correlation coefficient of 0.85. Further analyses of the mean distribution of the shoals within the throat of the inlet demonstrated the cause of timevarying rates of movement of points along the spiriferous east shoreline of the inlet. Shoreline movement rates were plotted on a time-space plane and isolines of shore movement rates contoured. The result was a three-dimensional image of shore movement rates over time and distance. The position of the centroid of the inlet shoal distribution at different times was superimposed upon the three-dimensional image. This revealed that variations of shoreline movement rates along the shore at any point in time are dependent on the mean position of the inlet shoal distribution. Also, the direction of movement of the mean position of the inlet shoal distribution appeared to indicate the predominant direction of flushing action, that is, flood or ebb tides.
AN EXPERIMENT ON CLAY SUSPENSION UNDER WATER WAVES
Authors: Thimakorn Prida
Published: June 2019

The physical behaviour of water waves upon the suspension of fine cohesive clay was explored experimentally in a wave channel. Results obtained from the experiment show that equilibrium concentration is reached in the wave field some time about five hours after the initiation of waves. The ratio between the mean bottom concentration and the vertical average is constant and yields almost the same value within the range 1.17 and 1.34 at equilibrium and the bottom concentration at equilibrium is linearly proportioning to the maximum bottom velocity of waves. The dimensionless transient concentration possesses a relationship also with the bottom velocity and the bottom shear stress can be related to the maximum value of the ratio between the bottom concentration and the vertical average value found within a short time after the initiation of waves.
INTEGRATION AND COMPUTATION IN AN ENVIRONMENTAL STUDY
Authors: Hinwood J.B. , Watson J.E. , Burrage D.M.
Published: June 2019

A high level of integration of disciplines and use of a centralised computer data base and programming system were seen to offer advantages in a study of the marine and coastal environment of the Port Melbourne Authority. These goals were only partially attained but the effort was well worthwhile.
VISUALLY OBSERVED WAVE DATA AT PT. MUGU, CALIF.
Authors: Weggel J. Richard , Schneider Christine
Published: June 2019

A Littoral Environment Observation (LEO) Program was established along the West Coast of the United States in 1968. This program provides for visual observations of waves and surf conditions to be made systematically on a daily basis. The data addressed in this report were collected at three LEO sites (as shown in Figure 1) at Pt. Mugu California, located 50 miles northwest of Los Angeles. In order to evaluate the reliability of wave heights and periods collected using the LEO techniques, comparisons of visual observations and measured wave gage records were made. The study revealed that individual visual observations of breaker height can deviate significantly from measured wave heights even when the gage wave heights had been corrected for shoaling effects. On the average the LEO observations gave a fair estimate of prevailing wave heights. LEO estimates of wave period tended to overpredict the period of maximum energy density. It is presumed that this occurred because observers often fail to count smaller waves when making this measurement. Statistics of the gage measurements of wave height and LEO wave heights are reasonably close.
A MEASUREMENT OF SLOPE, CURVATURE, AND DIRECTIONAL SPECTRA OF WIND WAVES IN LAKE MICHIGAN
Authors: Liu Paul C.
Published: June 2019

Wave recording activity among coastal and oceanic engineers has increased rapidly in recent years, and ample wave data covering a large number of gage stations are now available. Directional wave spectra, however, are relatively scarce. The detailed knowledge of directional wave characteristics that correlate with the simultaneously recorded wind field is needed immediately for a proper understanding of the generation, growth, and propagation of a wave field. The data are necessary for engineering design, for verification and improvement of wave prediction models, and for provision of appropriate ground truth for calibrating remote sensing measurements. This paper represents the results of an effort to fulfill this need.
DIRECTIONAL WAVE SPECTRA AND WAVE KINEMATICS IN HURRICANES CARMEN AND ELOISE
Authors: Forristall G.Z. , Ward E.G. , Cardone V.J.
Published: June 2019

A realistic description of the kinematics of hurricane waves requires that the directional spectrum of the sea be known. Models for hindcasting the directional spectrum have existed for some time, but there has been a dearth of data available for checking the directional characteristics of the hindcasts. Hurricane Carmen in 1974 and hurricane Eloise in 1975 passed reasonably close to platforms in the Gulf of Mexico which were instrumented with wave staffs and electromagnetic current meters. The maximum recorded significant wave height was 29 feet. The simultaneous measurements of wave height and water particle velocity permitted estimates of the directional spectra to be made. The estimated directional spectra are complicated and often bimodal in frequency and direction. Swell from the center of the storm can propagate in directions over 90 degrees away from the direction of the shorter waves which are in local equilibrium with the wind. The hindcast model reproduces these directional features remarkably well. The measurements of wave kinematics also permitted tests of the accuracy of wave theories in high and confused storm waves. All of the unidirectional theories tested showed a bias toward overpredicting the velocity under the highest waves. However, the kinetic energy in the velocity components and the velocity probability distribution could be found to within a ten percent scatter using directional spectral concepts and linear wave theory.
BEACH CUSPS AT POINT REYES AND DRAKES BAY BEACHES, CALIFORNIA
Authors: Dean R.G. , Maurmeyer E.M.
Published: June 2019

Beach cusps, fairly common and periodic features along many shorelines have been the focus of numerous investigations. The primary efforts have been directed toward (1) determining a causative mechanism for their formation; (2) describing qualitatively the associated water motions and sediment transport; and (3) developing a predictive relationship for their spacing. As in other problems in nearshore dynamics (e.g. rip currents), it may be that there are various valid explanations for different occurrences of beach cusps. In addition to satisfying scientific curiosity, an improved qualitative and quantitative understanding of beach cusp mechanisms would contribute substantially to swash zone dynamics and to nearshore hydrodynamics and sediment transport in general. This paper describes a series of measurements of beach cusps and associated parameters carried out at Point Reyes and Drakes Bay beaches in northern California during the summers of 1977-1979. An attempt to idealize the beach cusp topography and the resulting swash hydromechanics led to a possible relationship between beach cusp spacing and swash parameters in which the spacing is linearly related to maximum swash excursion.
PHYSICAL PROCESSES AND SEDIMENT FLUX THROUGH REEF-LAGOON SYSTEMS
Authors: Roberts Harry H.
Published: June 2019

Studies of physical processes in reef-lagoon systems continue to emphasize the importance of waves and wave-induced currents at the reef crest as agents of sediment transport to backreef environments. These across-the-reef currents are also largely responsible for driving backreef lagoon circulation. Rapid energy transformations associated with the process of wave breaking at the reef crest are responsible for strong reef-normal surge currents. Estimates of energy loss, as determined by wave height changes caused by wave breaking, can be as high as 70-80%' for discontinuous reefs and >90% for continuous examples. The amount of energy loss is related to depth of water over the reef crest, a function of reef topography and tidal regime. Low-tide conditions promote the greatest incident wave modification and attenuation as a result of increased breaking-wave intensity. Under trade-wind conditions found in the Caribbean, surge currents of 50-80 cm/sec for durations of 2-6 sec are common in a low to moderate wave-energy setting (4-6 sec input waves, 40- 50 cm average heights). Sediments through the sand sizes up to pebbles are easily transported lagoonward by these periodic bursts of energy. Flow in shallow backreef lagoons (generally
BEACH PROFILES AND ON-OFFSHORE SEDIMENT TRANSPORT
Authors: Watanabe Akira , Riho Yoshihiko , Horikawa Kiyoshi
Published: June 2019

The on-offshore sediment transport due to waves on a sloping beach is studied by analyzing the laboratory test data on two-dimensional beach deformation. The net rates of sediment transport both inside and outside the breaker zone are evaluated from beach profile changes and are related to the nondimensional bottom shear stress or the Shields parameter. The importance of the critical shear stress and of asymmetrical to-and-fro water partical motion near the bottom is pointed out.
SECONDARY SAND TRANSPORT MECHANISMS
Authors: Smith A.W. , Gordon A.D.
Published: June 2019

The basic concept of coastal littoral drift consisting of a "river" of sand driven by the direct alongshore component of oblique waves has long been considered as a basis for littoral transport equations. This concept however is highly simplified since the actual littoral drift on real beaches represents only the final result of the inter-action of dozens or perhaps hundreds of secondary hydraulic processes which continuously occur in Nature. On many Coasts littoral transport is taken to represent the primary mechanism of beach recession or build-up but many of the secondary mechanisms themselves are only partially understood and their individual contributions to the primary process largely unexplored. This paper therefore discusses some of these secondary processes and since offshore- onshore sediment transport is probably the most important of these a mechanism for this transport mode is suggested based upon the interaction between wave energy and a work capacity parameter for the beach sediments.
RELATIONSHIP BETWEEN ALONGSHORE WAVE ENERGY AND LITTORAL DRIFT IN THE MID-WEST COAST AT TAIWAN
Authors: Hou Ho-Shong , Lee Chung-Pan , Lin Lung-Hui
Published: June 2019

Based on the wave pattern, the geographical location and the disposition of rivers, the littoral drift moves predominantly from NE to SW direction in section II as shown in Fig. 1. Seven rivers of rapid stream bring tremendous amount of sediments from the high mountain to the nearshore of this section in typhoon season (i.e. from June to September). But for the winter monsoon season, i.e. from October to the next April, the waves induced by NE monsoons migrate littoral drift from North toward South. Applying the energy approach for unidirectional steady flow derived by Bagnold(1963), the theoretical relationship between the littoral immersed weight transport rate and the alongshore breaking wave energy is found out. It reveals that the relationship is not strictly linear, i.e. the larger part of the alongshore breaking wave energy is supplied for transporting the sediment as the former increases. But for a coast having a steady oceanographical condition, the relationship could be considered as linear relation since the alongshore breaking wave energy is not varying very much. In this paper, the study of littoral drift vs wave energy at the Taichung Coast from the Ta-Chia River to the Ta-Tu River will be carried out. Using the wave records gained by the ultrasonic wave gauge at 19m depth and the littoral drift quantity obtained from long-term observation, the relationship between alongshore breaking wave energy and littoral immersed weight transport rate is found out. First, the waves which have the same direction are summed up. Then from "THE WAVE CHARACTER COMPUTING PROGRAM", the incident directions of these wave groups at 19m depth are determined. Then the alongshore breaking wave energy per unit time per unit length of beach could be calculated by the same PROGRAM.
SAND BED-FORM LENGTHS UNDER OSCILLATORY MOTION
Authors: Brebner Arthur
Published: June 2019

Tests were carried out in the oscillating water tunnel to determine the bed-form lengths of sand ranging from 0.1 mm to 0.55 mm subjected to oscillatory motion of various orbital diameters ranging from 0.15 m to 1.5 m and of various periods ranging from 3 to 15 s. The relationship for the bed-form length is given in the accompanying graph in dimensionless form.
SEDIMENT TRANSPORT PROCESSES AND COASTAL VARIABILITY ON THE ALASKAN NORTH SLOPE
Authors: Owens E.H. , Harper J.R. , Nummedal D.
Published: June 2019

Shoreline development and shore-zone sediment transport on the Alaskan North Slope are dependent upon levels of wave energy, sea ice conditions, and the ice-sediment characteristics of eroding tundra cliffs. Considerable variation exists between the coastal processes and the shore-zone morphology of the Chukchi and Beaufort Sea beaches, (respectively west and east of Point Barrow). The supply of coarse sediments (sands or gravels) and the volumes of material eroded from tundra cliffs are a function of the initial character of the cliff sediments and of the ice content of the exposed cliffs. As cliff heights decrease, the ice content of the cliff increases, erosion rates increase but the sediment supply rates decrease. Wave-energy levels are relatively high and maintain a constant level on the Chukchi coast. The transport system on this coast is continuous and is augmented by storm events. On the Beaufort coast, energy levels are much lower, transport processes discontinuous, and storm events are therefore more significant. Sediments supplied to the coastal zone on the Chukchi coast are derived largely from the erosion of tundra cliffs and the barriers are continuous, linear, and stable. Rivers are the primary source of coastal sediments on the Beaufort coast and the more variable energy levels produce unstable barriers that are subject to aperiodic transport processes.
FLUID MUD DYNAMICS AND SHORELINE STABILIZATION: LOUISIANA CHENIER PLAIN
Authors: Wells John T. , Roberts Harry H.
Published: June 2019

The coast of western Louisiana is presently receiving a new influx of fine-grained sediment from the Afcchafalaya River to the east, the first such sediment pulse in recorded history. The major effect of this sediment, which accumulates as fluid mud in the nearshore and at the shoreline, is to attenuate incoming wave energy, thus providing conditions favorable for further sedimentation. Examination of color infrared photography and comparison of observations from aerial overflights and information from ground reconnaissance undertaken periodically since 1969 indicate that mudflat sedimentation is increasing and appears to be moving to the west. When muds move ashore and begin to dewater after becoming "shore attached," they gain strength rapidly and can resist subsequent fair-weather wave 3 scour if their bulk density exceeds 1.20-1.25 g/cm . An understanding of why and how these fluid muds accumulate and move subaqueously may provide us with the ability to predict areas of future erosion and accretion along the western Louisiana shoreline.
A PHASED-DREDGING PROGRAM FOR SANTA CRUZ HARBOR
Authors: Walker James R. , Williams Peter J.
Published: June 2019

This project was undertaken to define the littoral processes and resultant shoaling mechanisms at the Santa Cruz Harbor California, entrance channel and to develop and evaluate alternative methods of mitigating the shoaling effects. Since November 1963, when the construction of the entrance channel was finished, the channel has shoaled such that it was almost completely closed during the winter months. The study involved analysis of shoaling mechanisms and contour changes and review of past dredging procedures. Sixteen structural and non-structural alternatives for mitigation of shoaling were analyzed. A phased-dredging procedure was developed and tested over 3 winter seasons. The concept was to dredge the channel periodically each winter while shoaling occurs, thereby keeping the Harbor open to navigation most of the time. The experience gained at this site may be of benefit to others in solving a shoaling problem or in designing a new small-craft harbor.
ORBITAL VELOCITIES IN IRREGULAR WAVES
Authors: Vis F.C.
Published: June 2019

Experimental and theoretical study to determine the applicability of linear wave theory for the description of the velocity field in irregular waves. A comparison between theory and measurement was executed both in frequency and in time domain. In frequency domain by means of the experimentally and theoretically determined frequency response functions of wave motion to orbital velocity, and in time domain by means of the measured and computed time records of the velocities. The time records for the velocities were computed from the measured waterlevel fluctuations by using the impulse response function method. The orbital velocities were measured contactless with laser-doppler equipment.
CAPRICORN COAST BEACHES
Authors: Patterson D.C. , Ford L.R.
Published: June 2019

The Beach Protection Authority of Queensland published in December 1979 a report outlining the results of its investigation into all the factors which determine the coastal behaviour of the 90 km strip of Central Queensland's coastline known as the Capricorn Coast (Fig. 1). The purpose of the investigation was to provide a detailed explanation of beach behaviour in this area including all the data necessary for the preparation of a comprehensive program of works and management strategies for improving beach conditions and minimising present and future erosion problems. This paper represents a brief summary of the contents of the published report.
GANSBAAI FISHING HARBOUR - THE DESIGN AND CONSTRUCTION OF A BREAKWATER ON A HOSTILE COAST
Authors: Van Dijk W.S. , Vonk A.P.M. , Retief G. de F
Published: June 2019

This paper describes the design and construction of a fishing harbour on a rocky coastline exposed to the prevailing south westerly swell of the South Atlantic and to severe westerly gales. Because of economic pressure the first phase of the development was undertaken without adequate knowledge of the wave regime or the topography of the sea-bed in the area and resulted in a virtually unusable harbour. The second phase of construction was therefore only embarked upon after extensive hydrographic surveys, wave recording and analyses, and probably the most exhaustive series of model tests ever undertaken for such a small project. These investigations and the good co-operation between research staff, engineers and contractors resulted in the elimination of most of the initial problems and the creation of a functional fishing harbour,
WAVE FORCES ON PILES OF VARIABLE DIAMETER
Authors: LeMehaute Bernard , Walker James , Headland John , Wang John
Published: June 2019

A method of calculating nonlinear wave induced forces and moments on piles of variable diameter is presented. The method is based on the Morrison equation and the linear wave theory with correction parameters to account for convective inertial effects in the wave field. These corrections are based on the stream function wave theory by Dean (1974). The method permits one to take into account the added wave force due to marine growth in the intertidal zone or due to a protective jacket, and can also be used to calculate forces on braces and an array of piles.
OFFSHORE ARTIFICIAL STRUCTURES AND THEIR INFLUENCE ON THE ISRAEL AND SINAI MEDITERRANEAN BEACHES
Authors: Nir Vaacov
Published: June 2019

The Israel Mediterranean shore forms a gentle curve from an almost easterly direction in north Sinai to an almost northerly direction in Israel. This shore forms the southeastern corner of the Levantine Basin which itself forms the extreme eastern part of the Mediterranean Sea. The length of the Israel shoreline from Rosh Haniqra near the Lebanese border to northern Sinai in the south is about 230 km, while the Sinai coast from Rafah to Port Said (Fig.1), is almost 200 km long. The coastline region consists largely of Quaternary carbonate cemented quartz sandstone, known by local name "kurkar". Recent faulting is responsible for the shape and, to a certain extent, for the morphology of large parts of the central coastline, which is characterized by kurkar cliffs (Neev et. al_. , 1973 it 1978).Wide sandy beaches are found in the southern parts, while an abraded rocky platforms occur mainly in the central and northern parts, where the beaches are narrow having kurkar cliffs at their backshor.e side. Four different morphological sections can be found in the Israel Mediterranean shore, (Nir, 1982). These differ in their beach and inland morphology on one hand, and in their sedimentological properties on the other. The four different sections from north to south are: 1) Rosh Haniqra to Akko. A sedimentological1y isolated region, bounded on both the south and north. Beach sediments are mostly of local calcareous material of marine origin. Akko promontory is the most northern limit of Nile derived sands and plays as the recent edge of the Nile sedimentary cell (Nir, 1980). 2) Haifa Bay. Wide sandy beaches, bounded on the north by the Akko promontory, and by the Carmel "nose" on the south. 3) Mount Carmel coastal plain, is sedimentologically somewhat isolated region with relatively narrow beaches and small kurkar cliffs. Sediments consist of both local and imported components. 4) The kurkar cliffs and sandy beaches from Caesarea to Rafah. Beaches of differing width having quite uniform petrographic components, mostly quartz grains originating from the Nile river and transported along the Sinai beaches to the Israeli beaches. Some of the present beach components are derivated from the abraded kurkar cliff.
PERFORMANCE OP SAND-FILLED TUBE SHORE PROTECTION TUKTOYAKTUK, NORTH WEST TERRITORIES, CANADA
Authors: Shah V.K.
Published: June 2019

Seawalls, revetments and groynes designed to protect shorelines require normally timber, natural stone or concrete for their construction. In Tuktoyaktuk, none of these materials is available and to avoid excessive costs, an alternative form of construction, using long sausage shaped tubes filled with sand, was devised on an experimental basis. Tuktoyaktuk is situated on the eastern side of Kugmallit Bay in the Western Arctic at north latitude of 69 deg. 27' and west longitude of 133 deg. 02'. It is approximately 90 miles north of Inuvik and 1450 miles northwest of Edmonton (figure 1). The area is mainly comprised of a long, narrow, boot-shaped peninsula oriented in approximately north-south direction, a complex lagoon, which has been developed as a harbour, east of the peninsula and an island straddling the mouth of the lagoon (figure 2). Certain dwellings exist at the southern and southeasterly shores of Tuktoyaktuk Harbour. A large majority of the inhabitants reside in settlements developed on the peninsula and the southern area linking the peninsula with the mainland. Tuktoyaktuk is used as a transfer point linking the Mackenzie River barge transport with coastwide shipping serving the western arctic seaboard and inland settlements and bases. As a result of this the TCJK settlement has grown to be the largest of the western arctic coast settlements.
SEDIMENTOLOGICAL INFLUENCES OF DETACHED BREAKWATERS
Authors: Rosen Dov Sergiu , Vajda Michael
Published: June 2019

Wave diffraction and refraction in the surroundings of a new detached breakwater induce currents strong enough to cause substantial local sediment transport and consequently morphologic changes, the main feature of which are sand spits or tombolos. As shown by field studies the morphologic changes cause an equilibrium state with some minor fluctuations due to changing wave climate. Model studies have also proved the existance of such an equilibrium state for any given geometry and sea state The present paper treats mainly this equilibrium state, but also attempts to explain the mechanism of sand transport characterizing the initial and transitional states. According to observations by the authors in small scale models, the transporting mechanism in the transitional state involves sea bottom erosion, especially near the breakwater heads outside the protected area, and transport of sand towards the shore of the sheltered area in the form of small migrating sand bars, which finally join the shore line and widen it. Results of experimental investigations conducted by the authors, for the particular case of high impervious breakwaters attacked by waves of normal incidence, as well as results of field and model studies given by others, are used to define relationships among the factors determining the equilibrium state and to base a new hypothesis regarding the equilibrium state. This hypothesis states that a morphologic and sedimentologic equilibrium is reached behind a detached breakwater, when the shape of the contour lines becomes such, that along the sheltered beach the diffracted waves have components of momentum opposed to the gradients of the mean sea level induced by radiation stress due to non uniform wave heights along the wave fronts approaching from both sides of the breakwater. The significant parameters characterizing the dimensions of the spit or tombolo in the equilibrium state are shown to be the relative length of the breakwater (compared to its distance from the original shore line), the relative distance from the original shore line (compared to the position of the breakers' line) and the relative height of the breakwater crest (above M.S.L, compared to the incident wave height).
POLOS STABILITY EFFECT OF BLOCK DENSITY AND WAIST THICKNESS
Authors: Scholtz D.J.P. , Zwamborn J.A. , Van Niekerk M.
Published: June 2019

Model tests were done with dolosse having the same shape and volume, but with different block densities, to determine the effect of block density on stability and to check whether the theoretical third-power relationship between block volume and relative block density is valid. From these tests it can be concluded that the higher the density of the block material the greater the stability becomes. Although the individual scatter is appreciable, the average results indicate that the stability of dolosse is inversely proportional to a power of about 2,3 of the relative density, which is significantly less than the theoretical power of 3. Model tests were also carried out on dolosse having the same mass and volume but with different waist-to-height ratios to determine the effect of waist-to-height ratio on the stability of a dolos armour. From the results of these tests it can be concluded that the stability of the armour decreases with increasing waist thickness, particularly for relatively high waist ratios.