bluuebunny/crossref_metadata_2025 huggingface dataset:
FIELD MEASUREMENTS OF WIND WAVE KINEMATICS
Authors: Battjes J.A. , Van Heteren J.
Published: June 2019

Measurements of surface elevations and three orthogonal subsurface velocity components have been performed from a platform in the southern North Sea, off the Dutch coast, in order to check linear spectral transfer functions relating subsurface velocities to surface elevations, to obtain information about the directional properties of the waves, and to investigate the velocity statistics. The data obtained as far do not cover a sufficiently wide range of conditions to permit general conclusions. Some preliminary results are presented in the paper.
HF RADAR MAPPING OF EXTENSIVE OCEAN WINDFIELDS
Authors: Dexter P.E. , Casey R.C.
Published: June 2019

The possibility of deriving parameters of sea wave spectra remotely from characteristics of radio waves at high frequency (HF) scattered from the sea surface was first raised when Crombie (1955) correctly deduced that Doppler frequency shifts in the signal returned from short range in his HF radar resulted uniquely from components of the sea wave spectrum having wavelengths exactly one-half the radio wavelength, and travelling radially with respect to the radar. Since then the technique has been expanded in two directions: (a) The use of ionospherically propagated-JiF radio waves ('Skywave' HF radar) to^ examine extensive ocean areas out to some 4000 km from the observing site, to obtain oceanographic and meteorological data suitable for input to synoptic observation systems. This approach has been developed through the experimental work of Tveten (1967) and Ward (1969), and the empirical technique proposed by Long and Trizna (1973) to allow the simple extraction of sea surface wind vectors from Doppler spectra of the backscattered radio signals. (b) The determination of directional sea wave spectra and sea surface currents at short ranges with HF radars operating in the groundwave propagation mode, based on theoretical analyses of the scattering process such as those of Barrick (1972). The HF Skywave radar constructed and operated at Townsville by the Physics Department of James Cook University has been employed for some years now on research into the possibilities for mapping sea states and sea surface winds over ocean areas surrounding Australia (Ward, 1969; Ward and Dexter, 1976; Dexter and Casey, 1978).
VELOCITY FIELD IN A STEADY BREAKER
Authors: Battjes J.A. , Sakai T.
Published: June 2019

An experimental investigation is described of the velocity field in a steady, spilling-type breaker, generated on a steady current by a submerged hydrofoil. Velocities have been measured with a laser-doppler system, and analysed with respect to mean and rms-values as well as Reynolds stresses. The results indicate that the turbulent flow field downstream of the initiation of the separation at the surface resembles that in a turbulent wake.
THE FLUID MECHANICS OF WAVES APPROACHING BREAKING
Authors: Peregrine D.H. , Cokelet E.D. , McIver P.
Published: June 2019

Numerical computations of water waves deforming until an overhanging, incipient jet has formed near the crest are studied in detail. Velocity and acceleration plots lead to the identification of three regions in the water which appear to be significant in the approach to breaking. In particular there is a region with particle accelerations greater than the acceleration of gravity.
VELOCITY AND PRESSURE FIELD OF SPILLING BREAKERS
Authors: Stive M.J.F.
Published: June 2019

The internal velocity and pressure fields of quasi-steady spilling breaking waves have been investigated experimentally. The internal flow fields are shown to be in qualitative agreement with a model proposed by Peregrine and Svendsen (1978). Furthermore a quantitative comparison is made with nonbreaking wave theories. Measurements of the pressure field are presented, and interpreted semi-quantitatively using the vertical momentum balance. Finally, it is shown how the integral properties can be obtained and analysed.
TWO-DIMENSIONAL SURF BEAT
Authors: Flick Reinhard E. , Inman Douglas L. , Guza Robert T.
Published: June 2019

Surface elevation and velocity measurements in shallow water on beaches show large fluctuations known as surf beat in the long period range from approximately 20s to 2000s (Munk, 1949; Tucker, 1950). A laboratory study was conducted to determine if two shoaling primary waves of nearly equal frequency would generate two-dimensional surf beat at their difference frequency. The experiments, carried out in the Scripps Institution of Oceanography Hydraulics Laboratory 30 m glass walled wave channel, show that the beat frequency motion in the channel consists of the sum of a forced progressive wave and two free standing waves. The progressive wave is forced by the local nonlinear interaction of the primary waves and grows sharply in shallow water. One of the free standing waves is generated directly by the wavemaker. The data is consistent with the hypotheses that the second, much larger, free wave is generated in shallow water as the reflection of the long, forced progressive wave, leading to the observed standing wave surf beat pattern.
LONG WAVES GENERATED BY COMPLEX BOTTOM MOTIONS
Authors: Hammack J.L. , Raichlen F.
Published: June 2019

Studies of tsunami generation often employ simple models of the sea floor dislocations to permit tractable analytical solutions. Although these solutions provide basic insight into the generation process, they are incapable of producing explicit results for prototype events where both the spatial and temporal distributions of the sea floor dislocation may be quite complicated. Herein we exploit the apparent linearity of the generation process and demonstrate both the use and validity of the superposition principle to construct solutions for complex bed motions. Analytical and experimental results are presented for a monopolar dislocation (block upthrust or downthrow) with a complex time-displacement history. The time history used in the computations is obtained from an integrated accelerogram recorded at Pacoima Dam, near Los Angeles, during the earthquake of February 9, 1971. A complex spatial deformation is not used in order to enable experimental verification of the analytical results. This is unfortunate since it appears that the details of the time-displacement history are not important for prototype phenomena where the motion may be considered instantaneous. However, it is important to note that the analysis treats both space and time variations in an identical manner; hence, confirmation of this approach for complex time variations strongly suggests analogous behavior for complex spatial variations. Finally, we examine and compare several alternative time-displacement histories for the mean motion. It is shown that the results for each mean motion can be unified by introducing a velocity as a descriptive parameter which is based on the kinetic energy input of the moving bottom to the overlying fluid.
ON THE CORRECTION OF LAND-BASED WIND MEASUREMENTS FOR OCEANOGRAPHIC APPLICATIONS
Authors: Hsu S.A.
Published: June 2019

Simultaneous offshore and onshore wind measurements were made at stations ranging from Somalia, near the equator, to the Gulf of Alaska. Offshore data obtained from standard U.S. NOAA buoys, research platforms, and merchant ships were compared with data from coastal stations. The results indicated that, under the commonly observed speed of 5-6 m/s, land measurements of mean wind speed are only 63% of the offshore mean speed. Furthermore, it was found that only those stations located in the beach area that measure wind speed above both the internal boundary layer and the nocturnal inversion height represent offshore conditions. In order to correct land-measured wind data, a formula is developed and verified by all 2/3 existing data sets. A simplified equation, i.e., U = 3 U1 s is proposed for offshore applications. Criteria for in situ wind measurements near the coast are outlined. Data reduction procedures for inland stations are also provided.
NUMERICAL MODELLING OF TROPICAL CYCLONE STORM SURGE
Authors: Sobey Rodney J. , Harper Bruce A. , Mitchell George M.
Published: June 2019

Details are presented of a general numerical hydrodynamic model for the generation and propagation of tropical cyclone or hurricane storm surge. The model, known as SURGE, solves the two-dimensional depth-integrated form of the Long Wave Equations using an explicit finite difference procedure, with tropical cyclone surface wind and pressure forcing estimated from an adaption of available models based on U.S. hurricanes. Variations in tropical cyclone parameters as well as the physical characteristics of a coastal location such as bathymetry and details of capes, bays, reefs and islands are accommodated by the model. The accuracy and stability of the numerical solution have been confirmed by a comprehensive wave deformation analysis including quasi-non-linear effects and the open boundary problem has been overcome by the use of a Bathystrophic Storm Tide approximation to boundary water levels. A detailed sensitivity analysis has identified the principal surge generating parameters and the model has been checked against an historical tropical cyclone storm surge. SURGE has been used extensively in the northern Australian region and examples are presented.
VERIFICATION OF A WAVE REFRACTION MODEL UTILISING RECORDED AND OBSERVED WAVE DATA
Authors: Henderson G. , Webber N.B.
Published: June 2019

There are few references in the published literature to the verification of wave refraction models utilising field data. More often, such models have been compared to the results of analytical solutions or using laboratory models. This paper reviews the present state of knowledge of such verifications and describes a method which has been successfully employed at a coastal site in the central English Channel. The procedure involves hindcasting recorded Waverider Buoy wave information from a nearshore region to deep water. A comprehensive coverage of wind data has been utilised to provide the offshore wave approach direction. Wave orthogonals have then been tracked inshore and the breaking wave heights and directions compared with observed data. The results show reasonable comparison where the waves are free from diffraction. However, for oblique wave attack, diffraction around headlands produces evident anomalies.
TRANSIENT FINITE-DIFFERENCE TSUNAMI CALCULATIONS
Authors: Skovgaard Ove , Jonsson Ivar G.
Published: June 2019

The applicability of a time-stepping approximate finite difference method is tested for the response of a plane incoming tsunami of small amplitude meeting an idealized island (see Fig 1). The resulting amplitudes are compared with the exact solution, which comes out of solving the linear shallow water wave equation for the area in question. Since this wave equation excludes dissipation (bottom friction) and the Coriolis force, these terms are omitted in the Boussinesq equations, formulated as mass and momentum conservation, which are the bases of the finite difference scheme. Grid size is 1 x 1 km. The incoming wave is time-harmonic with a period of T = 480 s; the (test) solution to the wave equation is thus a truly steady-state solution. The finite difference scheme, however, has a so-called "cold start" and so it is transient in principle. During a time corresponding to three periods, in which disturbances from the open boundaries still have only a small effect on the wave field near the island, the time-series of signals in selected points can define a steady response, though. Considering the inevitable shortcomings of a provisional study like the present, satisfactory agreement with the exact solution is met over the shoal in Fig 1. We have thus a promising starting point for more elaborate studies, comprising new filtering algorithms for the boundaries, tests with real transient input signals, and including non-linearity, bottom friction, and the Coriolis force. The numerical scheme used is the so-called System 21, developed at the Danish Hydraulic Institute and placed at our disposal for the present study.
BARRON RIVER DELTA INVESTIGATION
Authors: Robinson D.A. , Cook D.J. , Barff J.G.
Published: June 2019

The Barron River flows to sea through a 50 km2 alluvial Delta on the narrow coastal plain near Cairns, Queensland in north eastern Australia. The Delta is in the tropics at 17 degrees south latitude. Most of the 2175 km2 catchment lies above 450 m above sea level. The coastal portion of the catchment has an average annual rainfall in excess of 2000 mm. River flows are highly variable with peak flood flows of over 4000 m3s"', and dry season flows of less than 15 m3s"'. The Delta is tidal with ocean tides having a range of 1.8 m at Spring Tides. There are three water storages on the catchment, one on the upper catchment having an ungated spillway and a capacity of 407 x 106 m3 for irrigation purposes and the other two just upstream of the Delta, are a small weir of 1.7 x 106 m3 capacity to regulate water supply to the Barron Gorge Hydro-electric Power Station, and Copperlode Falls Dam on Freshwater Creek, a 45 x 106 m3 ungated storage to provide water to Cairns City and the nearby Mulgrave Shire. The Delta consists of alluvial soils which support 3600 hectares of sugar cane farm land. The beaches in the Delta are being developed as resort towns and dormitory suburbs. Sand and gravel is reularly dredged from the lower reaches of the main river in the Delta at the rate of 50,000-80,000 m3 per year. Increasing scarcity of sand sources, and the concern that dredging and dam construction is threatening beach sand sources have raised conflicting pressures on the Authority which licences the extraction of sand and gravel from the river. This, coupled with regular flooding of the Delta and the cutting of major highways, and the continuing erosion of cane farm land has initiated a major data collection programme as a prerequisite to formulating solutions for the flooding and erosion problems.
GEOLOGICAL CONTROLS ON PROCESS-RESPONSE, S.E. AUSTRALIA
Authors: Roy P.S. , Stephens A.W.
Published: June 2019

Results of regional geological studies on the southeastern Australian coast and inner continental shelf suggest that broad relationships between nearshore sediments and morphologies are often the result of factors other than incident waves and wave-induced currents. Five main factors (including wave action) have been identified: 1. degree of compartmentization and sand bypassing, 2. incident wave energy, 3. offshore sand loss to deep water sinks, 4. inherited sediment characteristics, and 5. substrate control. It is thought that these factors have controlled coastal evolution in the past and also influence present-day coastal changes. Identification of the role played by individual factors in specific areas provides valuable information on coastal sediment budgets.
BEACH CUT IN RELATION TO SURF ZONE MORPHODYNAMICS
Authors: Wright L.D.
Published: June 2019

Field experiments on the coast of Southeastern Australia, supplemented by systematic observations in a variety of environments in other parts of the world, indicate at least three quasi-discrete modes of subaerial beach cut, each of which is related to a distinct set of mechanisms. For any given set of incident wave conditions, the operation or non-operation of a particular mode of cutting depends on the morphodynamic state of the surf-zone and beach. Steep, reflective, beaches are susceptible to cut under moderate swell conditions by accentuated runup and berm overtopping associated with subharmonic resonance. Appreciably more energy is required to cut flat dissipative beaches. Cut of dissipative beaches involves high setup which oscillates at infragravity frequency and allows the bores of broken waves to penetrate to the backshore. Beach states intermediate between the reflective and dissipative extremes are subject to cut by both the modes just described as well as by scour in the embayments of topographically arrested rips which can cause significant localized erosion even when the coast regionally is accreting. Beaches which most commonly exhibit intermediate topographies are the least stable and most mobile.
BEACH RESPONSE TO VARIATIONS IN BREAKER HEIGHT
Authors: Short A.D.
Published: June 2019

The breaker wave height required to produce a particular beach-surfzone morphology is examined for micro-tidal, medium to fine sand beaches. Waves >2.5m produce dissipative beach systems with wide surfzones and shore parallel bar/s and channel/s. Breakers between 1 and 2.5m result in rip circulation and associated rhythmic morphology (crescentic bars, rip channels, megacusps, etc). Low waves (
NEARSHORE CURRENTS ON A PARTIALLY ROCKY SHORE
Authors: Sasaki T.O. , Igarashi H. , Harikai S.
Published: June 2019

Nearshore circulation on a partially rocky shore at Haranomachi Beach, Fukushima Prefecture, Japan has been studied in terms of field observations and numerical experiments for a low energy wave regime and with a physical experiment for a high energy wave regime. No significant distinctions were found in current velocity and rip current spacing between rocky and sandy beaches for the low energy wave regime, however the positions of rip currents were affected by wave refraction from the offshore exposed rocky bottom. On the other hand, since the surf zone bed is largely occupied by an exposed rocky floor for the high energy wave regime, the circulation exhibited fairly irregular patterns, so that a rip current becomes difficult to define, however the positions of inflow across the breaker line were found to be coincident with wave convergence zone.
TOPOGRAPHIC CONTROL OF RUN-UP VARIABILITY
Authors: Bradshaw Mark P.
Published: June 2019

This paper presents observations of currents recorded in the swash zones of a number of morphologically different types of beaches in order to demonstrate the large variability in run-up patterns that exists primarily because of variability in beach face and surf zone configuration. Run-up spectra are shown for steep and flat beaches under low (
SAND TRANSPORT BY WAVES
Authors: Van de Graaff Jan , Tilmans Wiel M.K.
Published: June 2019

In coastal engineering practice frequently a distinction is made between two different modes of sand transport: - longshore transport - onshore-offshore transport From a theoretical point of view the longshore transport phenomenon is not as complicated as the onshore-offshore phenomenon. In the longshore mode of transport, the variations in time (wave period scale) are less important since the current velocity component in the longshore direction is nearly constant in time. In the onshoreoffshore direction both the time-variations of (orbital) velocities and sediment concentrations have to be considered in order to be able to compute the resulting net sediment transport. Since our quantitative knowledge of the time variations of the concentration is extremely poor at this moment, realistic calculations of the onshore-offshore transport, based on the actual physics involved, cannot be made. In many practical coastal engineering applications the onshore-offshore transports play an important role, however, and therefore a reliable description is urgently needed. Swart (1974;1976) presented an experimentally based computing method. The Coastal Engineering Group of the Delft University of Technology has been studying the onshoreoffshore transport phenomenon since 1968. Since the beginning of the investigation a rather experimental research method has been used also since the measuring devices lacked to measure real concentrations. The outcome of the present investigation, however, is rather surprising in some aspects. Bijker, Van Hijum and Vellinga (1976) reported on some preliminary results.
A SURVEY OF "RANDOM" WAVE GENERATION TECHNIQUES
Authors: Ploeg J. , Funke E.R.
Published: June 2019

Techniques of producing waves in hydraulic models and laboratory flumes have evolved from the simple electrical-mechanical technique of some 15 years ago, to the present sophisticated hydraulic-electric servo systems, controlled by on-line computers and capable of producing a large number of different types of sea states. An accurate definition of the required sea state has become very important, since it has been shown that different types of wave trains, although all having the same significant wave heights and periods, can produce large differences in the results of model tests. Even a specification of the input spectrum, including all relevant spectral parameters, is not sufficient. The occurrance of wave groups, for instance, has to be defined separately. Table 1 illustrates which sea state parameters (A-E) need to be defined and controlled in the laboratory for different types of model studies (1-9). This is just shown as an example, and does not pretend to be a definitive statement. There exists presently a great variety of different techniques and methods to produce irregular waves and there is no assurance that testing the same model in different laboratories will give similar results. As a first step to address this problem, it was thought to be useful to determine the variety (or perhaps similarity) of all laboratory wave generation systems presently used. A discussion with representatives of a number of hydraulics laboratories and ship towing tanks in the spring of 1979 led to the organisation of a survey of wave generation and analysis systems. The results of the survey are shown in the same format as the questionnaire. A list of all institutes which participated is also included.
NEARSHORE SUSPENDED SEDIMENT LOAD DURING STORM AND POSXTSTORM CONDITIONS
Authors: Kana Timothy W. , Ward Larry G.
Published: June 2019

As part of the DUCK-X experiment at the CERC field research facility at Duck, North Carolina in September, 1978, suspended sediment measurements were made along the CERC pier. In situ bulk water samples were collected during a moderate northeast storm and two days later during post-storm wave conditions. Concentrations varied from approximately 0.01 g/1 to over 10.0 g/1. Vertical arrays of suspended sediment samples indicated that concentration decreases rapidly up to two meters above the bed, then remains relatively constant, reflecting the nature of the suspension; intermittent suspension of sand near the bed, and continuous washload higher in the water column. Concentrations were at a maximum during storm conditions when measured values were 3 to 5 times higher than during non-storm conditions. The total load of sediment in a pier cross section during sampling periods in storm and post^storm conditions was calculated from arrays of 49 samples each. With H1/3 exceeding 2.3 HI and the surf zone width over 300 m during the storm, the total load of sediment in suspension was approximately 10 times higher than during poststorm conditions (Hi 73 - 1.2 m and surf zone width approximately 100 m) . Estimates of the longshore flux of suspended sediment indicate that as much as 60 times more sediment was transported during storm than during post-storm conditions. Longshore transport of sediment measured from 5 cm above the bed to the surface reached the equivalent of 22,330 m^/day. This value corresponds very closely to longshore transport predicted from wave energy flux. During post-storm conditions, on the other hand, transport of suspended sediment accounts for less than one-third of the transport predicted from wave energy flux.
ONSHORE-OFFSHORE TRANSPORT AND BEACH PROFILE CHANGE
Authors: Hattori Masataro , Kawamata Ryoichi
Published: June 2019

In this paper a model is presented to describe onshore-offshore sand transport in the surf zone. The model is based on the physical consideration that when the net transport attains a state of equilibrium, the power expended through gravitational force in suspending sand grains is balanced by that due to the uplifting force arising from the turbulence generated by breaking waves. Two important parameters controlling sand transport are the dimensionless fall-time parameter and bottom slope.
ON-OFFSHORE SEDIMENT TRANSPORT RATE IN THE SURF ZONE
Authors: Sawaragi Toru , Deguchi Ichiro
Published: June 2019

In this paper, models of the distribution of net on-offshore sediment transport based on two-dimensional equilibrium beach profiles and an equation of continuity of sediment transport are proposed. Various parameters of net on-offshore sediment transport in those models are discussed. Furhter, the relative importance of bed load and suspended load in the two-dimensional beach deformation are examined by measuring both of them on model beach experiments.
FIELD MEASUREMENTS OF SAND MOTION IN THE SURF ZONE
Authors: Inman Douglas L. , Zampol James A. , White Thomas E. , Hanes Daniel M. , Waldorf B. Walton , Kastens Kim A.
Published: June 2019

Forcing functions and sediment response were measured during two comprehensive surf zone experiments. The experiments included simultaneous measurements of waves and currents, and the movement of sediment as bed and suspended load. The longshore transport of suspended load was found to be about 10 to 20% of the tracer-measured load. Results from tracer measurements of the longshore transport of bed load indicate that previous measurements may have misestimated the effective "tracer layer thickness," and a more rigorous method is proposed.
A SEDIMENT TRAPPING EXPERIMENT AT SANTA CRUZ, CA.
Authors: Seymour R.J. , Domurat G.W. , Pirie D.M.
Published: June 2019

Santa Cruz Harbor is located on the northern coast of Monterey Bay, California, approximately 104 kilometers south of San Francisco and 22 kilometers north of Moss Landing, as shown in Figures 1 and 2. Harbor construction was authorized by Congress under the Rivers and Harbors Act of 195S, which provided for a harbor to accommodate light-draft vessels in Woods Lagoon at the eastern boundary of Santa Cruz. The authorized improvements included two rubblemound jetties 360 meters long and 243 meters long, on the west and east sides of an entrance channel, respectively - an entrance channel approximately 270 meters long, 30 meters wide and 6 meters deep, reducing to 45 meters in depth at the same width for an additional HI meters - an inner channel, 240 meters long, 45 meters wide, 45 meters deep, reducing to 3 meters in depth at the same width for an additional 100 meters - a'turning basin approximately 90 meters long, 75 meters wide, and 3 meters deep, and a sand-bypassing plan. Figure 3 shows the project features. The armor units of the seaward side of the west jetty are 28-ton quadripods. The west jetty also has a concrete cap extending to elevation +4. 8 meters MLLW. Construction of the harbor was initiated in February of 1962 with the dredging of Woods Lagoon and the start of work on the west jetty. The west jetty was completed in February 1963. Then work began on the east jetty, and it was completed in April 1963. The entrance channel was dredged to the project dimensions in the summer of 1963. Construction of Santa Cruz Harbor was completed in November 1963, with the exception of the sand-bypassing plant. Construction of the sand-bypassing plant was deferred until the littoral drift rate could be more accurately determined.
NEARSHORE SEDIMENT TRANSPORT STUDY EXPERIMENTS
Authors: Seymour R.J. , Gable C.G.
Published: June 2019

The Nearshore Sediment Transport Study (NSTS) is a multi-institutional research program with the objective of developing improved engineering predictive models for transport of sediment. both longshore and cross shore, by waves and currents. The program is sponsored by the Office of Sea Grant (OSG), an agency of the National Oceanic and Atmospheric Administration (NOAA). A general introduction to the objectivesi schedule and organization of the NSTS program was presented at the 16th ICCE by Seymour and Duane (1979). Shortly after the Hamburg Conference, the first major field experiment was conducted at Torrey Pines Beach. California, in November, 1978. The second major experiment was conducted 14 months later in February, 1980 at Leadbetter Beach, in Santa Barbara, California. Each of these experiments involved levels of measurement intensity that appear to exceed by a large factor those of any similar work. Because of the large data sets obtained and the importance of these data to other investigators in coastal processes, the NSTS project is making them available promptly. In the following sections, a general description will be given for each of these experiments and information supplied on how the data may be obtained.
OPENING AND MAINTAINING TIDAL LAGOONS & ESTUARIES
Authors: Jenkins Scott A. , Inman Douglas L. , Bailard James A.
Published: June 2019

Sedimentation in tidal lagoons and estuaries has become an acute problem, particularly where there has been over-dredging to accomodate today's deep draft vessels, 0(15m). The rise in mean sea level, which created natural estuaries, has not kept pace with the demand for greater draft ships. The limited number of navigable lagoons confronting a growing demand for more inland waterways has encouraged reconstruction dredging of some closed or partially filled lagoons. Man's efforts to deepen existing or relict estuarine systems have disturbed the steady state equilibrium of the systems. Sedimentation acts continuously to restore this equilibrium by either of two,processes. One is floculation of fine-grained fluvial born sediments, a process accelerated when an estuary is deepened thereby allowing greater salt wedge intrusion. The other is the interception of the longshore transport of coarse grained beach sediments by the lagoon inlet. The larger tidal prism of an enlarged lagoon draws a greater percentage of the longshore transport into the lagoon from the adjacent surf zone. In the absence of wave suspension within the lagoon, very .little of this sediment is carried back out of the lagoon on ebbing tides. These sedimentation processes confront the coastal engineer with several distinct problems. A particular set of counter-measures are needed against accumulations of cohesive fines from the rivers, another set against accretion of cohesionless coarse grained sediments from the beaches. Still other methods are needed to reopen a closed lagoon. Dredging has been the most widely practiced solution to all of these problems for the past 150 years. It is a solution we may not be able to afford indefinitely. In addition to intrinsic high rates of energy consumption and equipment breakdown, there are ever-growing costs associated with dredge spoils disposal. Ninety percent of the material annually dredged is contaminated by heavy metals, concentrated in the floes from either natural erosion of country rock or industrial sources (Malloy, 1980).
RESEARCH IN SOUTHERN QUEENSLAND INTO THE MANAGEMENT OF COASTAL SAND DUNES
Authors: McKenzie James B. , Barr David A.
Published: June 2019

Queensland's Beach Protection Act (1968-1974) resulted, inter alia in the formation of the Beach Protection Authority, which is responsible for investigating coastal erosion, planning remedial works, recording and evaluating results of investigations, and various other functions. Control of windblown sand and retention of vegetated and naturally stable coastal sand dunes are valuable means of decreasing coastal erosion and because of this the Authority implements a broad research program into the management of coastal dunes in Queensland. Field trials are carried out at the Authority's Dune Management Research Station on South Stradbroke Island to determine methods of repairing, stabilizing and managing coastal dunes. The research program conducted so far consists of fifteen separate field trials within four general areas of investigation:- (a) Dune Forming Fences Two trials were installed in blown-out sections of the frontal dune to compare different types of semi-permeable fences (eg. wooden slats) and brush matting (a surface mulch of tree branches) on the basis of their ability to accumulate windblown sand and initiate dune formation. (b) Dune Stabilization Techniques Three trials were installed on bare dunal areas to evaluate methods of temporary sand surface stabilization (organic mulches and spray-on materials) as an aid in establishing dune vegetation. (c) Dune Vegetation Two trials were conducted to produce and compile information on the performance of important or potentially useful dune plants. (d) Plant Nutrition Eight trials using different combinations and rates of fertilizer were used to study methods of improvement of establishment and early growth of dune stabilizing plants, particularly sand spinifex grass (Spinifex hirsutus). Good establishment and rapid early growth is required in order to accelerate, improve, and decrease the costs of, the stabilization process.
WIND AND SEDIMENT MOVEMENT IN COASTAL DUNE AREAS
Authors: Hails John R. , Bennett John
Published: June 2019

Little is known about how air-sediment interaction processes control the differential rates and direction of dune migration along the coast of South Australia. Information is needed on sand transport and dune formation in order to establish better guidelines for conservation and agricultural management programmes in areas that are undergoing erosion. The writers, with financial support from the Coast Protection Board, Department for the Environment, South Australia, have commenced a pilot research project to examine dunes in the lower Coorong and adjacent areas in the southeast of the State (Figure 1). The aims of the project are - To determine: (a) instantaneous surface stress values on the windward slopes of active transgressive dunes; (b) sand movement over the crestline as a function of surface stress on the windward slope in order to establish the life expectancy of stability of individual dunes; (c) the extent to which the local topography affects the wind regime in the dunal areas. To obtain: (a) air trajectories over and around transgressive dunes; (b) information on dune geometry (slope inclinations, crest heights, base lengths, etc.).
TURBULENCE GENERATED BY WAVE BREAKING ON BEACH
Authors: Sakai T. , Inada Y. , Sandanbata I.
Published: June 2019

Horizontal and vertical velocities are measured with a hot-film anemometer (HFA) and a two-component laser-doppler velocimeter(LDV) in surf zones on uniform slopes of about 1/30 in two wave tanks. The turbulence generated by wave breaking is detected from the records. Following three aspects of the turbulence are discussed : (1) the distribution of the turbulence intensity in the surf zone, (2) the variation of the vertical distribution of the turbulence during one wave period and (3) the variation of the Reynolds stress during one wave period. It is found that the pattern of the distribution of the turbulence in the surf zone depends on the breaker type. A model is proposed, by extending the turbulent wake theory, to explain the variation of the vertical distribution of the turbulence during one wave period.
CONSTRUCTION SEQUENCE MODELLING FOR HARBOUR BREAKWATER
Authors: Henory Roger W.
Published: June 2019

Gansbaai fishing and pleasure craft harbour is situated approximately 160km east of Cape Town. Modifications and extensions were required to the existing breakwater as well as construction of an internal access mound. An investigation was commissioned into alternative construction methods and construction sequences for the modifications and extensions. The aim of the study forming the subject of the paper was to establish as accurately as possible the optimum sequence of construction for the various phases of the work and to establish the optimum construction methods to be adopted so that any damage to the work was minimised as construction proceeded. By means of a three dimensional hydraulic model, alternative construction methods and sequences were investigated under varying wave heights and sea conditions. Minimum wave heights and the sea direction causing damage or localised displacement of the elements of construction were studied.
DESIGN AND CONSTRUCTION OF HADERA OFFSHORE COAL UNLOADING TERMINAL
Authors: Yaron S.L. , Shimoni J. , Tzachar C. , Zwemmer D.
Published: June 2019

A new coal fired power plant constructed by the Israel Electric Corporation on the Mediterranean coast off Hadera, Israel, requires the import of 3.3 million tons of coal per year. As there is no port on the Israeli Mediterranean coast capable of handling the 60,000 to 140,000 DWT bulk carriers required for transferring of coal, several studies were conducted in order to decide on the most feasible facility for mooring and unloading these boats. Rather than expand existing ports or build a new protected port, a decision was finally taken to construct an unprotected offshore terminal at the power plant site. The terminal was designed to accommodate bulk carriers of up to 140,000 DWT in the first stage, and up to 170,000 DWT with future expansion. The design of the coal unloading terminal in an unprotected environment created the need to develop design criteria as well as operational and structural systems that will respond to problems arising from unloading bulk in the open sea. As there was no known precedent of an unprotected unloading terminal, the criteria was based on experience in existing offshore loading terminals, laboratory tests and engineering judgment. The construction of an unprotected offshore terminal, at a cost of $60 million (excluding mechanical equipment), represents a considerable saving of time and money in comparison to the expansion of existing ports or construction of a new protected facility.
LITTORAL PROBLEMS IN THE PORTUGUESE WEST COAST
Authors: Oliveira I.B. Mota , Valle A.J.S.F. , Miranda F.C.C.
Published: June 2019

This paper summarizes a study recently concluded of a sandy coastal reach, 110 km long, on the Portuguese west coast. The final objective of that study was the design of a sea defense master plan covering all the stretch, to be built at a long term. That coastal reach has been under a strong erosion process for a long time. The history of the problem and its present situation were thoroughly analysed. Different techniques, related to different aspects of the general problem (wave climate, littoral transport, sand bypassing, long term evolution under accretion or erosion conditions, groin field, spiral beaches, etc. were used. In what concerns littoral transport and sand bypassing the improvement of currently available methods was tried. The need of an accurately defined wave climate was felt; some rather disappointing results can sure ly be related to the lack of accurate wave data.
DURBAN BEACHES RECLAMATION : PRACTICAL ASPECTS
Authors: Barnett K.A.
Published: June 2019

Much controversy has revolved around the stability of Durban's beaches over the years and in its concern for this valuable tourist asset, the Durban City Council commissioned several studies culminating in a commission in 1961, jointly with the South' African Transport Services, with the Council for Scientific and Industrial Research in which they were required to investigate the possibilities of maintaining the harbour entrance channel at certain depths and to find some means to stabilise and improve the Durban beaches.
IMPROVEMENTS IN MODELLING RUBBLE-MOUND BREAKWATERS
Authors: Timco G.W. , Mansard E.P.D.
Published: June 2019

Physical modelling is a technique which is commonly used in the design procedure of rubble-mound breakwaters. For reliable results it is necessary that the model tests accurately represent the prototype situation. In this paper, two significant improvements in modelling of breakwaters are presented. They are the generation of realistic sea states at the test site, and the simulation of the breakage of the armour units by using units which have mechanical properties properly scaled from the prototype units. These techniques have been used to study the recent breakwater failure at Riviere-au-Renard, Canada.
STABILITY ANALYSIS FOR A RUBBLE-MOUND FOUNDATION THROUGH IRREGULAR WAVE TEST
Authors: Yamamoto Masato , Asakawa Tsutomu
Published: June 2019

Irregular wave tests have been conducted to research into the stability characteristics of armor units for a rubble foundation of a composite breakwater. A cover layer to protect the rubble foundation from erosion had two layers of tetrapods. Waves higher than H]_/]_Q (the average height of the highest 10% of all waves) caused damage to armor units at the point of critical stability. This suggested that wave height changes in the surf zone should be taken into consideration for design purpose.
IRREGULAR WAVE TESTS FOR COMPOSITE BREAKWATER FOUNDATIONS
Authors: Tanimoto Katsutoshi , Yagyu Tadahiko , Goda Yoshimi
Published: June 2019

The stability of armor units for the rubble mound foundations of composite breakwaters has been investigated under the action of irregular waves. The tests establish that irregular waves are more destructive than regular waves, when the height of regular waves is set equal to the significant wave height. The stability number, defined by Hudson, for quarry stones and concrete blocks with simple shapes is formulated on the basis of irregular wave tests. The stability number is expressed by two parameters of h'7/7]/3 and K, where h' is the crest depth of the rubble mound foundation, #1/3 is the design significant wave height, and K is a parameter for the combined effects of the relative water depth and the relative berm width of the rubble mound foundation to the wavelength. The design mass of armor units can be calculated by the stability equation with the stability number. The application of the proposed method to the results of the irregular wave tests demonstrates that the damage percent for the quarry stones is at most 3.5% at the design condition and the damage progresses rather gradually for the action of higher waves. On the other hand, the damage of the concrete blocks almost jumps beyond the design wave height. In particular, the drastic damage is often caused in the case of high rubble mound foundations. The proposed method is confirmed, however, to be applicable for the ordinary low mound foundations with a sufficient safety.
AUTOMATED DIGITAL SIMULATION OF TIDES S LONG WAVES
Authors: Henry R.F.
Published: June 2019

A system for indirect programming of shallow-water models is discussed, particular attention being given to facilitating successful operation by novice users. Pre-developed programs are used to check numerical coding of model layout, to execute the finite-difference computations required at each time step and to analyse the computed surface elevations and velocities. Many error-prone steps are thus eliminated and model development is speeded for modest increase in computation costs.
TIDAL EROSIONAL EFFECTS ON A BULKHEAD SYSTEM
Authors: Noble Ronald M. , Roth Wolfgang H. , Patil Uday K.
Published: June 2019

In the design and construction of waterfront bulkhead systems, it is essential to consider the coastal effects of tides, waves, boat wakes, currents, bottom sediment movement and bottom scour. Many improperly designed bulkhead systems experience severe loss of backfill and toe materials with the bulkhead eventually failing if it is not corrected in time. Inadequate drainage, joint connections, and/or inadequate toe protection are typically the causes of failure. This paper describes an investigation of a bulkhead system supporting a large waterfront development in southern California which was experiencing widespread sinkhole development in the bulkhead's backfill and was on the verge of losing toe material. The objective of this investigation was to determine the extent and cause of ongoing subsurface erosion, to evaluate its effect on the bulkhead stability, and to recommend and design mitigative measures. The cause of the erosion was determined to be piping of fine grained soils due to inadequate backfill drainage. A remedial drainage scheme was designed and field-tested, and several structural repair schemes were suggested for portions of the bulkhead where accumulated damage affected the integrity of the structure.
BREAKAGE OF CONCRETE ARMOR UNITS
Authors: Markle Dennis G. , Davidson D.D.
Published: June 2019

A survey of existing Corps breakwaters with concrete armor units and hydraulic model tests of rubble-mound breakwater trunk sections protected with dolosse were conducted to determine the effects of broken armor units on breakwater stability and to establish some criteria by which decisions can be made as to when maintenance and rehabilitation work should be initiated on damaged concrete armor unit cover layers. The survey revealed that where good engineering designs were used, prototype breakage has been random and has not exceeded about 3 percent of the total number of units placed. The model tests, conducted with both breaking and nonbreaking waves with no overtopping, revealed the percent breakage can be quite a bit higher than 3 percent before the overall functional integrity of dolos cover layers is affected.
RESPONDING TO AN SOS - SAVE OUR SHORES
Authors: Heiberg MG E.R. , Duscha L.A. , Lockhart J.H.
Published: June 2019

The rising sea level issue affecting U.S. coastal policy is reviewed, and the U. S. Army Corps of Engineers coastal role is summarized. Three case studies are provided to demonstrate the successful application of several structural devices available to solve different coastal problems. The coastal engineer, and other scientists, should contribute significantly to the information upon which society bases its decisions on use of the shoreline.
SAN FRANCISCO'S SOUTHWEST OCEAN OUTFALL
Authors: Eisenberg Y. , Treadwell D.D.
Published: June 2019

The Southwest Ocean Outfall, with an overall length of 23,400 feet and a capacity of 450 million gallons per day, will be a major element of the Clean Water Program of the City and County of San Francisco, California, U.S.A. Offshore, the Outfall will cross one of the world's major active fault zones, the San Andreas. Outfall construction started in 1981 and is scheduled to be completed by early 1985. The shoreward 3,000 feet is being built from a pile-supported trestle; offshore, the Outfall conduit sections will be placed using a barge designed and built specifically for the project. Oceanographic, coastal, geotechnical, and seismic conditions pertinent to design are presented along with discussions of specific Outfall design and construction features.
CYLINDRICAL LONG WAVE INTO A CYLINDRICAL SHELF
Authors: Power Henry
Published: June 2019

Based on the linear non-dispersive theory, the reflection of a Converging Cylindrical long wave, of wave length L, onto a Cylindrical shelf, of radius r = a and positive or negative height A h relative to an otherwise flat bottom, is study analitically. It is found that these linear approximation agrees well with the existing non-linear numerical solution when the ratio a/L is large enough. It is also found that these two-dimensional reflection process is the contrary of the corresponding one-dimensional case, since the solution of these problem gives a negative reflected wave for a positive step and a positive reflected wave for a negative step.
A SURVEY OF MAN-MADE TIDAL SWIMMING POOLS ALONG THE SOUTH AFRICAN COAST
Authors: Bosman D.E. , Scholtz D.J.P.
Published: June 2019

A large number of man-made tidal swimming pools (two examples are shown in Figure 1) exist along the South African coast. They are usually situated on rocky outcrops in the close vicinity of popular sandy bathing beaches to provide protected bathing conditions in these areas mainly for children and elderly people. Some tidal pools, especially along rocky coast, provide the only safe bathing facilities. Besides affording protection against waves and surfzone currents the pools provide protection from sharks. A large number of tidal pools were built during the early 1950s along the Natal South Coast after the occurrence of a relatively large number of shark attacks on bathers on that coast. The semi-diurnal tide with a range of about 1,5 m along the South African coast makes it possible for pools to be built such that water replenishment can occur during every high-water (approximately every 12 hours) during both neap and spring tide periods. Presently, there exists a great need for more tidal pools as part of the demand for more recreational facilities along the South African coast. However, no information on design criteria could be found in the literature.