bluuebunny/crossref_metadata_2025 huggingface dataset:
SEA-LEVEL MEASUREMENTS IN THE WASH BAY
Authors: Binne & Partners B&P
Published: June 2019

A report (Binnie and Partners, 1965) on the water resources of the Great Ouse Basin put forward proposals for storage in the Wash of fresh water from the four rivers draining into the bay. The scheme suggested was to take the form of a barrage, enclosing about a third of the area of the bay, behind which fresh water would be stored in raised impoundments. Four years later (Binnie and Partners, 1970) this proposal was superseded by a scheme for storage in bunded reservoirs built on the foreshore at the head of the bay. The current Wash Feasibility Study (commenced in 1971) is expected to highlight the most suitable scheme of this sort following a programme which includes field data collection, hydraulic and mathematical model testing and site investigations. The scheme as currently envisaged would take the form of bunded reservoirs built (largely from dredged sea bed material) on the foreshore close to the outfall of the river Great Ouse and connected by tunnel to intakes on that river, and later on the river Nene. To meet increasing demand further impoundments could be built along the foreshore to store water drawn from the other rivers draining into the Wash. Figure 1 shows a possible reservoir scheme which is among those being considered. Continuous sea level observations have been made at 4 points in the Wash bay (figure l) using automatic level recorders. The purpose was to provide information on tides and surges in connection with the feasibility study.
SPECTRA AND BISPECTRA OF OCEAN WAVES
Authors: Houmb Ole Gunnar
Published: June 2019

The two dimensional (directional) power spectrum gives an adequate description of water waves that may be regarded as a linear superposition of statistically independent waves. In such cases the sea surface is linear to the first order and the surface displacement is represented by CO n(t) = Z an sm(u> t + n) n=l where an are the amplitudes of individual waves and is a Tn randomly distributed phase angle, and the process is stationary. Under such circumstances the wave surface is Gaussian, which means that ordinates measured from MWL are normally distributed rf they are sampled at constant intervals of time. It is equally important that the wave heights are Rayleigh distributed. This formulation of the wave surface is widely used e.g. in wave forecasting. There are, however, phenomena such as wave breaking, energy transfer between wave components and surf beat which can only be described by higher order effects of wave motion (1, 2, 3, 4). In this case the two dimensional power spectrum fails to give an accurate description of the wave surface. This means that the first and second order moments (mean and covariance) no longer give all the probability information, and we have to consider higher order moments (5, 6, 7).
SURF SIMILARITY
Authors: Battjes J.A.
Published: June 2019

This paper deals with the following aspects of periodic water waves breaking on a plane slope breaking criterion, breaker type, phase difference across the surfzone, breaker height-to-depth ratio, run-up and set-up, and reflection. It is shown that these are approximately governed by a single similarity parameter only, embodying both the effects of slope angle and incident wave steepness. Various physical interpretations of this similarity parameter are given, while its role is discussed m general terms from the viewpoint of model prototype similarity.
FIELD MEASUREMENTS OF NEARSHORE VELOCITIES
Authors: Huntley David A. , Bowen Anthony J.
Published: June 2019

Two component electromagnetic flowmeters are being used as the basis of an apparatus to measure nearshore velocities on natural beaches. The flowmeters are mounted on free standing tripods, 1 m. base side and 0.3 m. high, to measure the two components of horizontal flow, and have been used in depths of up to 4 m. and up to 150 m. from the shoreline. The apparatus has proved both flexible and reliable on beaches ranging from steep shingle (slope ^ 0.13) to very shallow sand (slope'*' 0.01) and under a wide variety of wave conditions, including full storm waves on a beach of intermediate slope ( ^ 0.04). Results show that a single flowmeter can be used on a tidal beach to measure the variation of the flow field along a line perpendicular to the shoreline. In this way edge waves and steady nearshore circulation patterns have been detected. If several flowmeters are placed on a line perpendicular to the shoreline, the progress of individual waves can be followed as they pass over each flowmeter in turn, and hence propagation speeds, changes of wave form and the development of lower frequency wave motion close to the shoreline can be studied.
WATER WAVES ON A BILINEAR SHEAR CURRENT
Authors: Dalrymple Robert A.
Published: June 2019

A water wave theory is presented to describe waves propagating on a bilinear shear current flowing in the direction of the waves. The theory is derived assuming an ideal fluid in which a current exists, having a vertical velocity profile which varies linearly from a mean water level velocity of Ug, an interfacial velocity Uj at depth, d, and a bottom velocity Uj$. The theory is developed first for small amplitude waves and then extended to any arbitrary order by a numerical perturbation technique for symmetric waves. For measured waves, an irregular form of the theory is presented to provide a representation of these waves for analysis.
DYNAMICS AND MORPHOLOGY OF SAND BANKS IN THE SURF ZONE OF OUTER TIDAL FLATS
Authors: Gohren Harald
Published: June 2019

Extended sand banks ranging up to some hundred acres with a crest height in the MHW-level are typical structures of the outer tidal flats of the south-eastern North Sea coast (Fig. 1). Primary forms grow up in the surf zone at the sea-side tidal flat border. They are formed like bars and migrate towards the coast with a surprisingly high velocity, up to 150 m/year. The movement is caused by strong erosion on the sea-side slope - which is shaped beach-like - and deposition at the steeper land-side (lee-side) slope. It was found that surf action at the bar is linked with strong unidirectional currents across the crest, Up to 100 cm/s. The currents are most likely generated by wave set-up in front of the bank and by wind-drift water motion.
A SCHEMATIZATION OF ONSHORE-OFFSHORE TRANSPORT
Authors: Swart D.H.
Published: June 2019

The investigation reported herein covers two aspects of the schematization of coastal processes on sandy beaches in a direction perpendicular to the coastline, viz.: (1) the prediction of equilibrium beach profiles and (2) the corresponding offshore sediment transport due to wave action. A physically-based schematic model of the onshore-offshore profile development was tested on available small-scale and full-scale model tests and physically-based empirical relationships were derived to enable the application of the model to both small-scale and prototype conditions.
TWO-DIMENSIONAL BEACH TRANSFORMATION DUE TO WAVES
Authors: Sunamura Tsuguo , Horikawa Kiyoshi
Published: June 2019

Important physical parameters controlling sandy beach transformation were clarified on the basis of the result obtained by a laboratory test. They were not only wave steepness but also beach gradient and a ratio of sand size to wave length. These parameters enabled the previously obtained laboratory beach profiles to be classified into newly proposed three beach types. These parameters were also found to be effective in grouping the data of shoreline changes both in laboratories and in fields.
TRACER TESTS IN THE MIDDLE NORTH SEA
Authors: Bratteland E. , Bruun P.
Published: June 2019

Tracing of sediment transport has so far mostly been concentrated in rivers and particularly in estuaries and in shallow coastal waters with main interest on navigational, erosional and some pollutionary aspects. With the ever increasing oil activites in the North Sea, knowledge on bottom sediment movements at large water depths is becoming more and more important. Little tracing has been undertaken on the offshore sea bottom at depths exceeding 20 - 30 meters.
FIELD INVESTIGATIONS OF SUSPENDED SEDIMENT
Authors: Basinski Tadeusz , Lewandowski Andrzej
Published: June 2019

A radiometric probe and sand traps have been applied to measure a distribution of the suspended sediment in a vertical profile. The first stage of investigations, comprising the laboratory tests and first experiments in the Baltic Sea, were carried out in 1973. As results of the above experiments calibration curve for radiometric probe has been obtained and some weak points of the method have been overcome. Six sand traps of bamboo type were situated in different distance from a shoreline and by turns perpendicular or parallel to the shoreline. It enables the determination of percentage distribution of suspended sand in vertical profile and along a bottom profile during a wave cycle.
SAND CONCENTRATION IN AN OSCILLATOR! FLOW
Authors: Bakker W.T.
Published: June 2019

In this paper first a numerical model is described concerning the velocity distribution in an oscillatory flow, respectively without and with resultant current . From the momentaneous velocity gradients eddy viscosities are derived . Using the approach of VANONI [13 , a numerical model is given for the calculation of sediment concentration and suspended sediment transport. In order to give reliable results, the bed-load concentration should be known This will be investigated in the future; at the moment the model only provides qualitative results.
PROTECTION OF SANDY COASTS IN DEPENDENCE OF THE DUNE - BEACH - TYPE
Authors: Erchinger Heie Focken
Published: June 2019

Barrier dunes are the natural protective structures against flooding the low-lying land during storm tides. Their strength and resistance are to be estimated in consideration of the total dune-beach-profile. For standardization of dune-beach-profiles 3 types are to be distinguished. For each of these types the necessary and the possible actions for stabilization of the barrier dunes and also of inshore dune areas are described.
EROSION PROBLEMS OF THE DUTCH ISLAND OF GOEREE
Authors: Krueger H.G.H. ten Hoopen , Bakker W.T.
Published: June 2019

At many places along the Dutch coast especially at the West side of the islands, erosion occurs. One of the islands where the erosion is severe, is Goeree, situated in the Delta area in the South-West of the Netherlands. (see fig. 1). This isle is recently connected with other islands by dams, (see fig.2). These dams built within the scope of the Delt aproject plans closing the tidal estuaries and to shorten the length of the coastline thus reducing the wave attack. This paper examines how the influences of the closure of the estuaries affect on the erosion of the neighbouring coast. To this end, the changes in vertical and horizontal tide caused by the closure as well as the wave induced littoral drift and the sand transport caused by a combination of tidal currents and waves before and after the closure, are computed. On the basis of this computations, a few suitable solutions for the reduction of erosion are discussed.
PHYSICAL CHANGES IN ESTUARINE SEDIMENTS ACCOMPANYING CHANNEL DREDGING
Authors: Sollitt Charles K. , Crane Stephen D.
Published: June 2019

The physical characteristics of estuarine sediments provide useful information about sediment sources, the nature of bottom surface stresses and sediment transport mechanisms. Changes in sediment composition and state are also useful indicators for estimating the effects of unnatural stresses on dependent chemical and biological activities. In this study, the changes in several sediment properties have been monitored for an isolated estuarine dredging project. The effect of estuarine hopper dredge activities has been evaluated for an Army Corps of Engineers project at Coos Bay, Oregon. The project included suction head dredging at a shoal area within the navigation channel and in bay spoiling at a deep section of channel one mile downstream from the dredge site. Core samples were taken five days before dredging and two, thirteen and seventy days after dredging at the dredge and spoil sites. Subsequent laboratory analysis of the core samples revealed that dredging induced redistribution of bottom sediments produced significant changes in several physical characteristics of the dredged material. Repeated resuspension of bottom sediments during the dredging and spoiling operations caused a net loss of fine grained sediments and light organic constituents. Several symptomatic changes were observed which validate this finding, including: an increase in median grain size and decrease in uniformity of dredge spoils due to loss of fine fractions; a decrease in volatile solids in the dredge spoils due to a net loss of organics; a decrease in porosity at the spoils site due to the ability of the coarse grain sediments to resist resuspension; and a decrease in hygroscopic moisture content due to loss of porous organics and silt-clay material from the spoils. Conditions following dredging were observed for a period of seventy days. Partial recovery of the sediment system was observed after two weeks with no further recovery in two months. The initial recovery came about due to the availability of local sources of resuspended sediment adjacent to the dredge site. This occured under low flow conditions in early fall. Complete recovery of the system was not observed and probably requires the relatively large sources of sediment which accompany heavy winter and spring runoff. Thus, the immediate effects of dredging may persist until the annual cycle of sediment erosion and deposition have occurred.
GEOMORPHOLOGICAL STUDIES OP THE ESTUARY OF RIVER NETRA7ATI NEAR MANGALORE
Authors: John E.J. , Cheryan K.P.
Published: June 2019

A number of factors such as wave conditions, tides, river flows, sediment charge, and ocean currents affect the features of an estuary. The understanding of the morphology of an estuary is essential on purely scientific considerations as well as applied to harbours. An attempt is made to study these inter-related and unsteady features and their combined effect on an estuary qualitatively. The estuary selected for the study is the one near Mangalore on the West Coast of India at latitude 12 51' north and longitude 74° 50' east, where two rivers, viz., river Netravati and river Gurpur meet together and join the sea. An effort is made to analyse the changes in the estuary in terms of prevailing wave conditions, river flows and sediment transport.
COMPUTING EOLIAN SAND TRANSPORT FROM ROUTINE WEATHER DATA
Authors: Hsu S.A.
Published: June 2019

Extensive wind profile measurements have been made over beaches, tidal flats, and small dune fields in Barbados, Ecuador, Florida, Texas, and on Alaskan Arctic coasts by the author and his associates during the past several years. The linear relationship between shear and wind velocities was further verified by these measurements, in conjunction with Bagnold's data from experiments in a Libyan desert. From these measurements, a simple method is developed for computing eolian transport of the most common sand particle sizes which occur on coasts and deserts by using only routinely available wind observations from nearby weather stations.
DAMAGES TO COASTAL STRUCTURES
Authors: Magoon Orville T. , Sloan Robert L. , Foote Gary L.
Published: June 2019

Coastal Engineering literature contains many references to coastal structures in the design or construction stage but few references to these same structures concerning their maintenance effectiveness subsequent to completion. This paper describes a successful long-term maintenance history of major coastal public structures in the State of California, U.S.A. It is concluded that proper design combined with prudent maintenance will result in effective coastal structures with long economic lifetimes.
STABILITY OF TIDAL CHANNELS DEPENDENT ON RIVER IMPROVEMENT
Authors: Barthel Volker
Published: June 2019

Many authors have dealt with the migration of sand in front of the German coast of the North Sea. Especially the movement of sand-banks and deep channels in the Weser-estuary was subject matter of several investigations with different results. Thorough investigations of selected cross-sections point out, that the movement goes on in some regions. The important shipping channel however has obtained a certain stability during the last 3o - 4o years, because the migration of sand occurs otherwise than in former days. This phenomenon coincides with the extensive and decisive river improvement measures in the inner part of the Weser-estuary. Current measurements in the investigation area demonstrate, that concentrated tidal currents in the deep channels guarantee a sufficient clearance for shipping purpose. It seems to be sure, that for the present no essential shifting of the main channel calls for important measures in the field of shipping, dredging and building of sea-marks.
PROCESS AND MORPHOLOGY CHARACTERISTICS OF TWO BARRIER BEACHES IN THE MAGDALEN ISLANDS, GULF OF ST. LAWRENCE, CANADA
Authors: Owens E.H.
Published: June 2019

Detailed field investigations of barrier beach morphology and processes at adjacent sites in the Magdalen Islands, Gulf of St. Lawrence, show that the two beaches are in distinctly different morphodynamic environments. The differences are expressed in terms of wave energy levels, sediment dispersal patterns, and nearshore, littoral, and dune geomorphology. The exposed west-facing coast has a steeper offshore gradient, is a zone of sediment bypassing, and has a complex sequence of three nearshore bars. Wave energy levels are lower on the sheltered east coast, and this is a zone of sediment redistribution and deposition with a single, linear nearshore bar. The different morphological characteristics of the two barriers are attributed to the spatial variation in energy levels and to the differences in offshore gradients on the two coasts. Computed wave energy values, derived from data monitored during two study periods (August and November, 1974), indicate that the mean wave energy levels were greater on the west coast as compared to the east coast by factors of 2.25 in summer and 2.95 in winter. This is due primarily to the dominance of winds out of the westerly quadrant throughout the year. 1975
SEDIMENTATION STUDIES ON THE NIGER RIVER DELTA
Authors: Mayor-Mora Ramiro , Mortensen Preben , Fredsoe Jorgen
Published: June 2019

An area of the Niger River Delta was studied from October 1974 to October 1975 in connection with feasibility studies and preliminary design for the development of a deep draught port in the Western portion of the Delta. The provision of a"100-kilometer, 8 or 10 m navigation channel through one of the entrances from the sea, up to new port facilities at Warri required comprehensive hydraulic, hydrographic and sedimentation surveys over such period.
CONCEPTS IN DESIGN OF COASTAL STRUCTURES
Authors: Kray Casimir J.
Published: June 2019

Certain design of the existing and proposed coastal structures for lateral loading in the United States is presently based upon the use of timber which is structurally inefficient in the elastic range. Figure 1, for example, indicates the plan of timber pile structure. This is a low- capacity dolphin composed of 19 piles, where piles in line of load carry two times axial load and three times larger shear than next piles in line of load. A relatively small load will be conducive to yield in the tension or compression members. Repetitive loading will gradually cause collapse of such structure. Being inefficient in the elastic range, timber structures may nevertheless, be adequate to provide safety for condition of shallow water, moderate wind pressures, moderate tides, and for moderate cross and reversing currents. However, such factors as: traffic safety, the possibility of marine borer attack, the location of structures in greater water depths, where they are exposed to waves, currents, tides, winds, and floating objects, indicate a need for larger capacity, more reliable and functional coastal structures consistent with the growing requirements.
NEAR-BOTTOM WATER MOTION UNDER OCEAN WAVES
Authors: Grace Robert A.
Published: June 2019

A two-year ocean experiment involving wave-induced forces on a test pipe mounted on the sea floor [Grace and Nicinski (1976)] involved the measurement of various quantities other than the pipe forces per se. A pair of these involved surface wave characteristics and wave-induced water motion at the level of the pipe centerline but off to one end of the pipe. These wave-kinematics data have been combined, and the results of this work make up this paper in which the emphasis is on the deterministic approach to data interpretation. Presented are comparisons of the velocity and acceleration data with the predictions of Airy and stream function theories plus discussion of the dispersion of the field data. The primary intent of the paper is to suggest to designers of bottom-laid structures, such as pipes, how values of the peak velocity and maximum acceleration of the water motion associated with a non-breaking design wave of specified characteristics can be chosen.
ARMOUR BLOCKS AS SLOPE PROTECTION
Authors: Willock A.F. , Price W.A.
Published: June 2019

Dolosse blocks were first described in 1966 by Merrifield and Zwamborn in a paper to the 10th Coastal Engineering Conference held in Tokyo. They reported a block whose design weight was one-fifth to one-sixth that of natural stone to resist the same wave height. The reaction of the profession was surprise and perhaps a little disbelief that the new block could have such a high K value. A considerable amount of testing followed in a number of hydraulic laboratories. Quite a lot of work was done at the Hydraulics Research Station at Wallingford and some interesting points came to light. The paper discusses how wave period and angle of attack affect block stability and suggests a way in which engineers might approach the problem of design of breakwaters.
LARGE SCALE MODEL TESTS OF PLACED STONE BREAKWATERS
Authors: Sollitt Charles K. , Debok Donald H.
Published: June 2019

Large scale model studies reveal that Reynolds scaling can affect the apparent stability and wave modifying properties of layered breakwater structures. Results of a study for a breakwater configuration designed to protect offshore power and port facilities in water depths to 60 feet are presented and discussed. The armor layer of this structure is formed from quarried rock of irregular rectangular parallelepiped shape, individually placed perpendicular to 1:2 seaward slope and crest. The resulting armor layer is relatively smooth, densely packed and very stable. Model studies of similar configurations were studied at 1:10, 1:20 and 1:100 scale ratios. Stability, runup, rundown and reflection were measured for a variety of water depths, wave heights and periods. Analysis of the large scale test results establish that the placed stone armor is approximately as stable as dolos armor units. Runup, rundown and reflection respond similar to rough, impermeable slopes. Comparison of large and small scale results demonstrate that relative increases in drag forces at lower Reynolds numbers decrease stability and runup in small scale models.
FLOATING BREAKWATER PERFORMANCE
Authors: Adee Bruce H.
Published: June 2019

The Pacific Northwestern United States contains large areas of protected waters with abundant recreational boating opportunities. The area also supports many commercial fishermen who use small boats in their fishing operations . As a result, there is a large demand for sheltered moorage for all these vessels. Traditionally, this demand has been accommodated by constructing rubble-mound breakwaters for marina protection. At present, most of the sites where rubble-mound breakwater construction is economically feasible have been used. Conditions at many of the remaining areas"for marina development are unsuitable for traditional techniques of marina construction. In general, the cost is too great because the water is too deep, or the environmental degradation resulting from marina development is unacceptable. To satisfy the demand for moorage, while at the same time overcoming the other restrictions, floating breakwaters have been employed at many new marina facilities. In order to optimize the configuration of floating breakwaters and to overcome the problems which have been encountered with their use, the University of Washington has undertaken a continuing program of research. The aim of this research has been to monitor the performance of existing breakwaters and to develop a theoretical model to predict performance. Using the theoretical model supplemented with appropriate model-scale tests, a series of parametric variations will be tested to determine the effects of these variations on breakwater performance. At present, several comparisons of the theory with model tests and full-scale performance have been reported by Adee (1975a, 1975b, 1976). This report is a continuation of this effort incorporating data obtained at the Friday Harbor, Washington floating breakwater.
RECENT- APPLICATIONS OF ARTIFICIAL SEAWEED IN THE NETHERLANDS
Authors: Ten Hoopen Henk G.H.
Published: June 2019

This paper deals with the effects and the method of laying of some recent emplaced artificial seaweed fields in the Netherlands. The weed is placed on the bottom in coastal waters to promote accretion or at least to prevent erosion along beaches and in gullies. The results of the three field trials, and some of the conditions, that govern the successful application of the seaweed, which will be discussed.
BUOYANCY-DRIVEN GRAVITATIONAL SPREADING
Authors: Koh Robert C.Y.
Published: June 2019

It frequently occurs in environmental fluid mechanics that a mass of less heavy fluid spreads horizontally on top of a heavier one or a more homogeneous parcel of fluid spreads within a stratified one. Examples of such phenomena include spreading of diluted sewage effluent either at the surface or in a submerged layer, the spreading of heated effluent discharged from power plants, and the spreading of oil on the surface of the sea. The general problem is rather complex, being influenced not only by the buoyancy but also by momentum, ambient turbulence and flow, surface tension, waves, wind and other complicating factors. This paper attempts to examine gravitational buoyancy-driven flow in a homogeneous otherwise motionless ambient by casting it in the form of an initial value problem. Several assumptions are made and two empirical coefficients are introduced which must be determined from experiments. Experimental data are also presented, compared with the results of the analysis and the empirical coefficients determined. Previous investigations on similar problems include Sharp (1969, 1971), Koh and Fan (1968, 1969, 1971), and Koh and Chang (1973).
COASTAL ENVIRONMENT AND A NUCLEAR POWER PLANT
Authors: De la Parra Ralph A.
Published: June 2019

Regulatory requirements and social constraints make it necessary to evaluate the environmental effects of a project and to incorporate into the design features to minimize adverse environmental impacts. This paper presents a case history of efforts to meet these requirements for a coastal power plant in southern California, Southern California Edison Company and San Diego Gas & Electric Company are jointly now constructing two additional units to the existing San Onofre Nuclear Generating Station, Being added are Units 2 and 3, The site, about 84 acres (34 ha,), is located within Camp Pendleton, a United States Marine Corps Base, about halfway between San Diego and Los Angeles, Califoria, The site (See Figure 1) is situated on the edge of a narrow coastal plain that extends from the coastline to a range of low hills, two miles inland, that have a maximum elevation of 1,725 feet (525 m) above sea level. The plain terminates at the beach in a line of wave-straightened cliffs, extending 60 to 80 feet (18 to 24m) above a narrow sandy beach. Numerous ravines are cut into the cliffs as a result of erosion by storm runoff from the coastal plain, Oceanographic features at the San Onofre site include a sandy bottom which slopes gradually to a depth of 60 feet (18 m) at about 10,000 feet (3,000 m) offshore. Mean maximum summer surface water temperature is about 73°F (23°C). During the fall and winter the water column is usually thermally homogeneous with a minimum temperature of approximately 56°F (13°C). Ocean currents at the site are chiefly tidally induced, although large scale low velocity circulation patterns are generally present. Very near to the southern California coast, local currents are influenced primarily by a combination of wind, tide, and local topography. The total current is ordinarily the sum of components due to wind, tide, and perhaps large-scale ocean circulations. Speed of the total current measured at San Onofre typically ranges from 0.10 to 1,75 knots, but averages 0.2 knots. San Onofre, Units 2 and 3 are being constructed southeast of, and immediately adjacent to existing Unit 1. Both the existing and the units under construction generate electrical power by using pressurized water nuclear reactors. Unit 1 has a capacity of 450 MWe and began commercial operation in 1968, Units 2 and 3 will each have a rated electrical output of 1,100 MWe. Commercial operation of Unit 2 is scheduled to begin in October 1981, and Unit 3 in January of 1983,
FLOW FIELD NEAR AN OCEAN THERMAL ENERGY CONVERSION PLANT
Authors: Sheppard D.M. , Powell G.M. , Chou I.B.
Published: June 2019

The flow field in the vicinity of an Ocean Thermal Energy Conversion (OTEC) Plant is extremely complex. The plants will normally be located in an area of relatively high surface currents and the location must also be such that a large temperature difference exists between the lower layers and the surface. Locations that demonstrate this characteristic can in many cases be modeled as a two layer fluid as shown in Figure 1. A number of different designs for the OTEC plants are being considered, but they all have one thing in common, a large vertical cold water pipe. This pipe extends from near the surface to some point in the cold water layer (see Figure 1). In some designs this pipe is as large as 40 m in diameter and 460 m in length. Having such a large object penetrating the interface between the two temperature layers in the presence of a shear flow can significantly alter the character of the interface. The highly turbulent wake downstream from the pipe can drastically effect the mixing across this density interface. A conventional heat engine cycle is used in the plant with the high temperature source being the water in the upper layers and the low temperature reservoir being the water from the lower depths. \ Since the temperature difference is small for this type of plant (20° max.), vast quantities of both high and low temperature water must be used. The intake and discharge for the warm water as well as the cold water discharge will be in the upper layer; the intake for the cold water will be in the lower layer at or near the end of the cold water pipe. The flow problem is thus one of a vertical cylinder in a two layer stratified shear flow with sources and sinks located along the cylinder.
HORIZONTAL DIFFUSION IN TIDAL MODELS AND SCALING CRITEREA FOR THERMAL-HYDRAULIC MODEL TESTS
Authors: Flugge Gerd
Published: June 2019

Near Brokdorf at the lower Elbe river (West Germany) a nuclear power plant is projected. The electric energy output shall be 1300 MWe; therefore the waste heat output will be about 2600 MWe. The maximum allowed temperature rise in the condenser amounts to 10 K. Accordingly the cooling water discharge is about 61 m /s in case of the provided once through cooling. For the purpose of the mixing and spreading of the discharged cooling water by mean tidal conditions and storm-tide conditions model tests have been carried out at the Franzius-Institut of the Technical University of Hannover.
NUMERICAL MODEL FOR DENSITY CURRENTS IN ESTUARIES
Authors: Fischer Karsten
Published: June 2019

In the estuarine mixing areas of salt water and fresh water the vertical stream velocity profile generally is strongly affected by the baroclinic forces, giving rise to upstream currents near the bottom. Such reverse currents occur not only in stratified estuaries, but also in estuaries of the well-mixed type |1|, and they may cause problems like strong shoaling areas, salt intrusion, or difficulties when disposing wastes or dredged material |3|. The contributions of the salinity variations to the tidal motion are comparable to the contributions from the fresh water upland discharge |1|. For well-mixed estuaries with negligible fresh water discharge, the tidal velocities and water elevations may be obtained from numerical vertically averaged models or from physical homogeneous-flow models, but for all other conditions or desired results one has to use numerical vertically discretized models or physical inhomogeneous-flow models. As numerical and physical models have different properties and deficiencies, they may be used complementarily rather than concurrently |4|, the farfield regime apparently becoming the domain of numerical models. The increased public and scientific interest in water quality problems led to the development and application of baroclinic numerical tidal models |5, 6| . The present paper is concerned with the question, how well the action of baroclinic forces can be represented by numerical techniques. As a test example, the salt wedge problems is tackled. Studies on salt wedges by means of physical models have been very sucessful |1, 7|, but mathematical approches were confined to analytical solutions for the stationary salt wedge |8 - 10| and simple geometric boundaries only. The numerical approach is free from these restrictions, giving a solution of the complete equations of motion, continuity, and convection-diffusion simultaneously.
WAVE CLIMATE ANALYSIS FOR ENGINEERING PURPOSE
Authors: Dette Hans H. , Fuhrboter Alfred
Published: June 2019

The North Sea (Fig. 1) is known as a random sea with depths in the southern part between 40 m and 100 m so that in contrary to the Atlantic and Pacific coastlines deep sea wave conditions do not exist. After four years of comprehensive wave measurements in the offshore area of the Island of Sylt near the Danish border a general analysis of the wave climate in that region was possible. In this paper results and suggestions will be presented under the aspect of replacing qualitative judgements by quantitative statements which are derived from the knowledge of the adjacent wave climate. Because the wave action varies from year to year a general time unit is not advisable for the evaluation of shore processes; therefore the time scale should be substituted by the integral of incoming wave energy occurring after a certain time. The investigated method of expressing the total energy of one season or one year in the electrical unit Kilowatthour (kWh) per meter (m) width of shoreline could prove in future as a feasible way of classifying the irregular seasonal and yearly wave intensities. It is further shown that wave measurements over a period of several years can be sufficient for the investigation of correlations between the wind velocities occurring from all directions and the resulting wave heights. In case of satisfying correlation factors it will then be possible to carry out feedback operations for periods from which only records of wind velocities and directions are available and even to hindcast the wave heights for certain not yet measured wind velocities.
RANDOM WAVE SIMULATION IN A LABORATORY WAVE TANK
Authors: Kimura Akira , Iwagaki Yuichi
Published: June 2019

Most of coastal engineering problems have been studied with monocromatic waves. However, sea waves which arrive at the coast are random. It is very difficult to estimate exactly the influence of these random waves to coastal structures. Then the model tests in a laboratory wave tank using random wave simulation techniques seem to be most desirable way to estimate the influence of randomness of sea waves. For this purpose, the accomplishment of random wave simulation system, which make possible generating random waves having statistically same properties as those of sea waves, has long been desired. The authors achieved to establish such a new wave simulation system. In this paper, the characteristics of this system are demonstrated experimentally through several cases of random wave simulations.
PROBABLE UTILIZATION LEVEL FOR A BARGE HARBOR
Authors: Czerniak Martin T. , Sonu Choule J.
Published: June 2019

The main consideration in harbor master planning is to maximize the amount of time that the harbor can be used. The potential level of harbor utilization can be evaluated by analyzing vessel performance during harbor operations in terms of the range of imposed environmental conditions. The harbor utilization level is expressed statistically as the probable amount of time that the harbor can be used as planned. In this paper, a siting study for a towboat-barge harbor will be described. This example will demonstrate the use of harbor utilization statistics for a simplified case of a single-purpose harbor and a single design vessel. This scheme can be applied to more complex cases of multipurpose harbors used by a variety of vessels. The purpose of this paper is twofold. First, it outlines the basic concept of harbor utilization statistics and their value to harbor master planning. While it seems that studies of this type would have been undertaken in the past, at present no examples have been found by the authors among published literature. Secondly, considering the lack of published information, it is beneficial to record some practical experience regarding towboat and barge systems as design vessels.
KINEMATICS OF BREAKING WAVES
Authors: Thornton Edward B. , Galvin James J. , Bub Frank L. , Richardson David P.
Published: June 2019

The sight and sound of breaking waves and surf is so familiar and enjoyable that we tend to forget how little we really understand about them. Why is it, that compared to other branches of wave studies our knowledge of breaking waves is so empirical and inexact? The reason must lie partly in the difficulty of finding a precise mathematical description of a fluid flow that is in general nonlinear and time-dependent. The fluid accelerations can no longer be assumed t o be small compared t o gravity, as in Stokes's theory for periodic waves and the theory of cnoidal waves in shallow water, nor is the particle velocity any longer small compared to the phase velocity. The aim of this paper is to bring together s ome recent contributions to the calculation both of steep symmetric waves and of time-dependent surface waves. These have a bearing on the behaviour of whitecaps in deep water and of surf in the breaker zone . Since spilling breakers in gently shoaling water closely resemble solitary waves, we begin with the description of solitary waves of limiting amplitude, then discuss steep waves of arbitrary height. The observed intermittency of whitecaps is discussed in terms of the energy maximum, as a function of wave steepness, In Sections 6 and 7 a simpler description of steady symmetric waves is proposed, using an asymptotic expression for the flow near the wave crest. Finally we describe a new numerical technique (MEL, or mixed Eulerian-Lagrangian) with which it has been found possible to follow the development of periodic waves past the point when overturning takes place. Measurement of waves, and vertical and horizontal water particle velocities were made of spilling, plunging and surging breakers at sandy beaches in the vicinity of Monterey, California. The measured breaking waves, derived characteristically from swell-type waves, can be described as highly nonlinear. Spectra and cross spectra were calculated between waves and velocities. Secondary waves were noted visually and by the strong harmonics in the spectra. The strength of the harmonics is related to the beach steepness, wave height and period. The phase difference between waves and horizontal velocities indicates the unstable crest of the wave leads the velocities on the average by 5-20 degrees. Phase measurements between wave gauges in a line perpendicular to the shore show breaking waves to be frequency nondispersive indicating phase-coupling of the various wave components. The coherence squared values between the sea surface elevation and the horizontal water particle velocity were high in all runs, ranging above 0.8 at the peak of the spectra. The high coherence suggests that most of the motion in the body of breaking waves is wave-induced and not turbulent.
DEFORMATION UP TO BREAKING OF PERIODIC WAVES ON A BEACH
Authors: Svendson Ib A. , Hansen J. Buhr
Published: June 2019

An experimental description is presented for 'the transformation of periodic waves which approach breaking on a gently sloping beach. The data include the variation of wave height, phase velocity, wave surface profiles, and the maximum value of the wave height to water depth ratio (H/h)max around the breaking point. The results are compared with the theories of sinusoidal and cnoidal wave shoaling, and the latter is shown in most cases to agree remarkably well when the laminar energy loss along the walls and bottom of the wave tank is included. An empirical relation is established between wave length to water depth ratio L/h at the breaking point and the deep water wave steepness H0/L0. Also the maximum wave height to water depth ratio at breaking shows considerably less scattering than found previously, when plotted versus S = hx L/h, hx being bottom slope.
WAVES USED FOR INTER-TIDAL DESIGN AND CONSTRUCTION
Authors: Keiller D.C. , Ruxton T.D.
Published: June 2019

The selection of suitable design criteria and methods of construction for works on inter-tidal sand flats has played an important part in a recently completed study (1) which examines the feasibility of storing fresh water in bunded reservoirs built on the foreshore of the Wash bay in the east coat of England (figure 1). Wave, wind and tide conditions have been monitored in the bay for 3 years to provide the information needed for design and construction. Experienced gained during the construction of a 15m high trial embankment (figure 2) located lm below mean sea level and 5 km from the sea defence bank has enabled us to examine the economy of construction methods. Short and long term observations on the bank will provide data on the performance of rip rap surface protection in field conditions.
SET-UP AND RUN-UP IN SHOALING BREAKERS
Authors: Van Dorn William G.
Published: June 2019

This paper reports the results of a series of laboratory experiments with periodic waves breaking on uniformly sloping impermeable beaches with the object of distinguishing set-up from dynamic shoreline motions due to partial reflection, the combination of which is normally referred to as 'run-up'. The principal findings are: 1. The mean set-up across the breaker zone was observed to be linear with mean slope proportional to the square of the bottom slope. The mean slope was independent of frequency over slopes of 0.04 or less, and increased with wave period over steeper slopes. 2. The dynamic run-up range was found to be proportional to the square of wave period times beach slope, in agreement with the equation of motion for a nearly frictionless block sliding on corresponding slopes under gravity. 3. The total run-up was poorly correlated with Hunt's empirical formula, nor could any reasonable deterministic justification of this formula be deduced from the present results. 4. Transient run-up was observed to considerably exceed steady-state values in most cases, suggesting that time-dependent momentum flux should be considered in the run-up of variable (natural) waves.
WAVE RUN-UP ON A SIMULATED BEACH
Authors: Sutherland A.J. , Sharma J.N. , Shemdin O.H.
Published: June 2019

A set of experiments concerning wave run-up in the presence of an offshore bar is described. Results pertaining to the direct relationship between incident waves and run-up heights are presented. It is clear that in the majority of cases the offshore bar does reduce run-up heights. The experiments showed that under certain conditions very large run-up and rundown heights are produced. This is ascribed to a resonance effect between either the basin, formed between the bar and the beach, or the beach face and the incident waves.
CHARACTERISTICS OF FLOW IN RUN-UP OF PERIODIC WAVES
Authors: Roos Ary , Battjes Jurjen A.
Published: June 2019

An experimental study is presented of some characteristic parameters of the flow in the up-rush and down-rush of periodic waves breaking on a plane, smooth slope. The water layer thickness has been measured as a function of time at four locations above still water level. Discharges and particle velocities have been calculated. The results have been made nondimensional on the basis of Hunt's formula for the run-up height. They appear to be either independent of the wave steepness H/L and slope gradient tan Ct or to be a function of a single similarity parameter £ - tana / yH/L only. An hypothesis is stated concerning a relation between the mean rate of overtopping of a dike by waves, and the run-up which would occur under the same circumstances on an uninterrupted slope. On the basis of this hypothesis the overtopping volume per wave can be normalized so as to make it independent of slope angle and wave steepness. A comparison of the result with measurements from other sources indicates a rough agreement.
ACTION OF NON-LINEAR WAVES AT A SOLID WALL
Authors: Nasser Mohamed S. , McCorquodale John A.
Published: June 2019

A one-dimensional finite difference model is developed to simulate the action of long non-linear shallow water waves at a solid barrier. A damping parameter is introduced to account for the centrifugal effects in the incident wave. A stability criterion for At/Ax is suggested. The numerical predictions of reflection and run-up compare satisfactorily with experimental results.
ESTIMATION OF INCIDENT AND REFLECTED WAVES IN RANDOM WAVE EXPERIMENTS
Authors: Goda Yoshimi , Suzuki Tasumasa
Published: June 2019

A technique to resolve the incident and reflected waves from the records of composite waves is presented. It is applicable to both regular and irregular trains of waves. Two simultaneous wave records are taken at adjacent locations, and all the amplitudes of Fourier components are analyzed by the FFT technique. The amplitudes of incident and reflected wave components are estimated from the Fourier components, and the incident and reflected wave spectra are constructed by smoothing the estimated periodograms. The wave resolution is effective in the range outside the condition of the gauge spacing being even integer of half wavelength. The ratio of incident and reflected wave energies in the effective resolution range is employed in estimating the overall reflection coefficient. The incident and reflected wave heights are estimated from the composite wave heights by energy consideration.
SPLASH - A MODEL FOR FORECASTING TROPICAL STORM SURGES
Authors: Barrientos Celso S. , Jelesnianski Chester P.
Published: June 2019

A significant portion of the damage by hurricanes is the storm surges. The National Weather Service has developed a dynamical-numerical model to forecast hurricane storm surges. The model is used operationally for prediction, warning, and planning purposes. The model requires fixed oceanographic and real time meteorological input data. The oceanographic data were prepared for the Gulf and East coasts of the U.S. and are stored as an essential part of the program. Meteorological data for any tropical storm are supplied by the forecasters or planners using the model. The model was applied to hurricane Camille 1969. Comparison between the observed and computed surges for Camille was satisfactory for prediction purposes.