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Showing papers in "Journal of Waterway Port Coastal and Ocean Engineering-asce in 1985"


Journal ArticleDOI
TL;DR: In this article, an alternative Stokes theory for steady waves in water of constant depth is presented where the expansion parameter is the wave steepness itself, and the first step in application requires the solution of one nonlinear equation, rather than two or three simultaneously as has been previously necessary.
Abstract: An alternative Stokes theory for steady waves in water of constant depth is presented where the expansion parameter is the wave steepness itself. The first step in application requires the solution of one nonlinear equation, rather than two or three simultaneously as has been previously necessary. In addition to the usually specified design parameters of wave height, period and water depth, it is also necessary to specify the current or mass flux to apply any steady wave theory. The reason being that the waves almost always travel on some finite current and the apparent wave period is actually a Dopplershifted period. Most previous theories have ignored this, and their application has been indefinite, if not wrong, at first order. A numerical method for testing theoretical results is proposed, which shows that two existing theories are wrong at fifth order, while the present theory and that of Chappelear are correct. Comparisons with experiments and accurate numerical results show that the present theory ...

488 citations


Journal ArticleDOI
TL;DR: In this article, the seaward limit of sediment transport was estimated using measurements collected at the Coastal Engineering Research Center's Field Research Facility located on the Atlantic Ocean, where the data consisted of measured wave characteristics and accurate repetitive nearshore surveys which extended out to a depth of 30 ft (9 m).
Abstract: Many coastal engineering problems require an estimate of the seaward limit of sediment transport, defined as the minimum depth at which no measurable change in water depth occurs. A procedure to estimate this limit depth was evaluated using measurements collected at the Coastal Engineering Research Center's Field Research Facility located on the Atlantic Ocean. The data consisted of measured wave characteristics and accurate repetitive nearshore surveys which extended out to a depth of 30 ft (9 m). Ten unique data points were used in the evaluation with measured limit depths ranging from 18 to 21 (3.9 to 6.4 m). These depths were overpredicted by an average of 4.6 ft (1.4 m). This difference could be reduced to 1.3 ft (0.4 m) by adjusting the coefficients in the equation. A reasonable correlation was also obtained using a simple multiple of wave height.

231 citations


Journal ArticleDOI
TL;DR: In this paper, the various types of breakwaters are classified into four general categories: Box, Pontoon, Mat, and Tethered Float, and the advantages and disadvantages of these three types are discussed.
Abstract: Floating breakwaters are inventoried. The various types are separated into 4 general categories, which are Box, Pontoon, Mat, and Tethered Float. The Tethered Float was identified as a special category but lacked sufficient prototype experience for detailed analysis. Advantages and disadvantages of the Box, Pontoon and Mat are presented. Hydraulic model test results and prototype experience for these 3 types are presented. Alternative mooring systems and anchorage methods are summarized. The engineering studies usually needed for a suitable design are outlined. Costs and design data for selected prototype installations are tabulated.

178 citations


Journal ArticleDOI
TL;DR: In this paper, the distribution of suspended sediment in the combined wave-current motion is theoretically predicted in the case of a plane bed, if the wave-induced motion close to the bed is sufficiently strong.
Abstract: The distribution of suspended sediment in the combined wave‐current motion is theoretically predicted in the case of a plane bed. This will be the case if the wave‐induced motion close to the bed is sufficiently strong. The theory is able to predict the average value of the concentration as well as the instantaneous values at a given distance from the bed. The theory is compared with laboratory and field measurements.

135 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of an increased discharge on the tide progressing into a river is evaluated quantitatively by gaging the signal recorded at upstream stations against a reference station, during intervals of effectively constant discharge; this process is repeated for progressively larger values of the discharge.
Abstract: The effect of an increased discharge on the tide progressing into a river is evaluated quantitatively by gaging the signal recorded at upstream stations against a reference station, during intervals of effectively constant discharge; this process is repeated for progressively larger values of the discharge. Upstream, the tidal range is reduced by an increased discharge; the time of arrival of low water is accelerated, while high water is retarded. The changes in range and in time may be represented by simple regression relations. Downstream an increased discharge causes a decrease in the effective friction during flood and an increase in it during ebb. Low water is retarded and high water is accelerated; some tidal components may actually be amplified over a segment of the river.

111 citations


Journal ArticleDOI
TL;DR: In this article, a numerical model is presented that predicts the transformation of monochromatic waves over complex bathymetry and includes both refractive and diffractive effects, and the solution is obtained for a finite number of rectilinear grid cells that comprise the domain of interest.
Abstract: A numerical model is presented that predicts the transformation of monochromatic waves over complex bathymetry and includes both refractive and diffractive effects. Finite difference approximations are used to solve the governing equations, and the solution is obtained for a finite number of rectilinear grid cells that comprise the domain of interest. Model results are compared with data from two experimental tests, and the capability and utility of the model for real coastal applications are illustrated by application to an ocean inlet system.

106 citations


Journal ArticleDOI
TL;DR: In this article, a description of major features and patterns of motion in water waves just after breaking is presented, and new observations utilized to develop a new qualitative picture of the breaking process.
Abstract: A description of major features and patterns of motion in water waves just after breaking is presented. Previous literature is synthesized and new observations utilized to develop a new qualitative picture of the breaking process. Both classic spilling and plunging‐type breakers are found to have similar initial breaking motions, but at vastly different scales. Two primary vortex motions are identified. A plunger vortex is initially created by the overturning jet, which in turn causes a splash‐up of trough fluid and subsequent formation of a surface vortex similar to the roller in a hydraulic jump. Introduced for the first time is the hypothesis that the plunger vortex translates laterally to push up a new surface wave with vastly different wave kinematics that continues propagating into the inner surf zone. Of primary interest is the outer or transition region where momentum is being exchanged between mean, periodic and random flow processes along with some energy loss. Evidence is presented from the lit...

97 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used two days of field data from a low slope beach with moderate wave heights (H∼70cm), some low order, normalized moments are compared to results from simple monochromatic and linear random wave models.
Abstract: Recent models for nearshore sediment transport suggest the importance of various moments of the fluid velocity field in determining transport rates. Using two days of field data from a low slope beach with moderate wave heights (H∼70cm), some low order, normalized moments are compared to results from simple monochromatic and linear random wave models. Not surprisingly, the random wave model is substantially more accurate than the monochromatic model. However, wave breaking and other nonlinearities introduce effects not explained by either formalism. The observed cross‐shore velocity variance is decomposed into wind wave and surf beat components. The surf beat contribution is maximum at the shoreline, while the wind wave component is maximum offshore. The total variance is nearly constant across the surf zone. This observation contradicts assumptions that are fundamental to many models of surf zone dynamics and sediment transport. Analysis of a wider range of wave conditions is needed to assess the general...

95 citations


Journal ArticleDOI
TL;DR: In this article, the authors give a model for the force exerted on vertical walls by the reflection of water waves with an arbitrary angle of incidence, and show that the maximum force per unit length can be caused by obliquely-incident waves rather than standing waves.
Abstract: Formulae are given for the force exerted on vertical walls: by the reflection of water waves with an arbitrary angle of incidence. The variation of the loads with all design variables show a number of unusual features, including the fact that the maximum force per unit length can be caused by obliquely-incident waves rather than standing waves. It is important for design that the whole range of possible wave conditions be considered. A method is developed for the numerical solution of the problem, which unlike the theory on which the above-mentioned formulae are based, solves the stated problem exactly. Results from the approximate formulae are compared with those from the numerical method, and are found to be surprisingly accurate over a wide range of wave conditions.

55 citations


Journal ArticleDOI
TL;DR: In this article, the effects of a rising sea surface are quantified and separated from other causes of shore retreat using a conservation of sand approach, and the authors found that sea level rise accounts for about 53% of the total shore retreat of 5.5 m/yr measured at Smith Island, Virginia, and for about 88% of measured, 1.7m/yr retreat of the barrier island south of Oregon Inlet, North Carolina.
Abstract: Using a conservation of sand approach, the effects of a rising sea surface are quantified and separated from other causes of shore retreat. Sitespecific data important in predicting shoreline changes are: (1) Initial shoreface and backbeach profile; (2) subsequent backbeach profile; (3) relative sea level rise; (4) grain size distribution of sediment landward of the shoreface; and (5) net quantity of sand‐sized material that enters or leaves a specified coastal reach. A key element of the approach, Bruun's assumption of a shoreface is dynamic equilibrium with the sea surface, was evaluated and found to be reasonably accurate. Field application of the method shows that sea level rise accounts for about 53% of the total shore retreat of 5.5 m/yr measured at Smith Island, Virginia, and for about 88% of the measured, 1.7‐m/yr retreat of the barrier island south of Oregon Inlet, North Carolina. Net sand losses account for the remainder. Because shoreface adjustments are required to maintain an equilibrium prof...

55 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of steady, uniform currents on random waves and associated waterparticle kinematics were investigated, and the basic equations describing the interactions between waves and currents were described.
Abstract: The effects of steady, uniform currents on random waves, and the associated waterparticle kinematics, are investigated. The basic equations describing the interactions between waves and currents ar...

Journal ArticleDOI
TL;DR: In this article, a simple empirical method is developed to relate statistical and energy based significant wave height estimates with CERC laboratory flume data from a 1:30 plane slope, two samples of field data, and stream function wave theory.
Abstract: Wave height parameters used in coastal and ocean engineering are grouped into three classes according to their definition bases: height statistics, energy, and monochromatic. Parameters within each class are easily interrelated for most engineering purposes. However, parameters from different classes are difficult to interrelate, particularly for shallow water applications where waves are near breaking. The often-used parameter “significant wave height” has traditionally been based on height statistics but many modern estimates are based on wave energy. A simple empirical method is developed to relate statistical and energy based significant height estimates. The method is developed with CERC laboratory flume data from a 1:30 plane slope, two samples of field data, and stream function wave theory. Since the two significant height estimates differ by over 40% in some laboratory cases, engineers should clearly recognize the distinction between them.

Journal ArticleDOI
TL;DR: In this paper, two approximate methods are presented for the calculation of the wave induced forces and moments on a vertical, surface-piercing cylinder of elliptic cross section, which provide a substantial reduction in computational effort when Compared with the exact solution which involves the numerical evaluation of Mathieu functions.
Abstract: Two approximate methods are presented for the calculation of the wave induced forces and moments on a vertical, surface‐piercing cylinder of elliptic cross section. Both methods provide a substantial reduction in computational effort when Compared with the exact solution which involves the numerical evaluation of Mathieu functions. One method involves the expansion of the exact expressions for the forces and moments for small values of the elliptic eccentricity parameter. The second method is based on Green's theorem and gives rise to an integral equation for the fluid velocity potential on the cylinder surface. Numerical results are presented for a range of relevant parameters and show excellent agreement with the computed values of the exact solution.

Journal ArticleDOI
TL;DR: In this paper, a model developed to optimize the design and operation of containerports is described and demonstrated, and the model minimizes total port costs, including the costs of dock labor, facilities and equipment, ships, containers, and cargo.
Abstract: A model developed to optimize the design and operation of containerports is described and demonstrated. The model minimizes total port costs, including the costs of dock labor, facilities and equipment, ships, containers, and cargo. It accounts for queueing delays to ships, mutual interference among cranes, minimum work shifts, and storage yard requirements. Model results are mainly used to determine the optimal combination of berths and cranes under various circumstances and to show that total costs per ship or unit of cargo served can be reduced by increasing the number of cranes per berth and berth utilization above present levels.

Journal ArticleDOI
TL;DR: In this paper, the Coulomb friction between soil grains is found to be the most important wave damping mechanism in soft soil beds, e.g., clays and silts.
Abstract: Wave damping by wave-soil interactions are examined quantitatively using the Coulomb-damped poro-elastic theory recently developed. The dispersion relation is obtained explicitly. It is found that the Coulomb friction between soil grains is by far the most important wave damping mechanism in soft soil beds, e.g., clays and silts. This mechanism is highly nonlinear owing to the dynamic softening behavior of soils. Large waves damp much quicker than small waves. Simple formulas and charts are presented for estimation of the wave damping by soil motion for wide ranges of soil wave parameters. Wave lenghts are also modified by the bed motion by up to ±\N 15%.

Journal ArticleDOI
TL;DR: In this paper, a system is described for sampling coastal data from a remote central station under computer control, which handles wave measurements from offshore buoys and nearshore pressure sensors, and velocity components from current meters and anemometers.
Abstract: A system is described for sampling coastal data from a remote central station under computer control. The data gathering network handles wave measurements from offshore buoys and nearshore pressure sensors, and velocity components from current meters and anemometers. Coastal station locations range from Hawaii to North Carolina with system interconnection through ordinary dial up telephone lines. Data are objectively edited automatically, analyzed and are available for remote display within a few minutes of the observation. Measuring instruments, system hardware, operations, and reports are described.

Journal ArticleDOI
TL;DR: In this paper, the authors used boundary integral equation method (BIEM) to estimate the wave-induced pressure on a pipeline in a two-dimensional domain, assuming that the soil structure and fluid are incompressible.
Abstract: Wave‐induced pressures are an important design consideration for oil and natural gas pipelines buried in the marine environment. Realistic problems are three‐dimensional in nature and involve waves approaching the buried pipeline at oblique angles and special pipeline geometries. For fluid flow in a sandy soil where liquefaction does not occur and fluid acceleration terms are negligible, Darcy's law can be used. Assuming that the soil structure and fluid are incompressible, results will show the wave‐induced pressure in the domain being governed by the Laplace equation with associated boundary conditions on the domain boundaries. The pressure distribution on the pipeline is obtained using the boundary integral equation method (BIEM). The BIEM is economical because the computations are performed only on the two‐dimensional surface boundaries of the solution domain rather than throughout the entire three‐dimensional domain. The first problem analyzed is the two‐dimensional case where the pipeline is paralle...

Journal ArticleDOI
TL;DR: In this article, a method of estimating wave runups on plane, smooth slopes is presented, which uses empirical formulas to predict monochromatic wave runup for a wide range of surf conditions.
Abstract: A method of estimating wave runups on plane, smooth slopes is presented. The method uses empirical formulas to predict monochromatic wave runups for a wide range of surf conditions. Intuitive arguments are used to support the form of the equations. The analysis shows that wave nonlinearity has a strong influence on the runup of nonbreaking, monochromatic waves. Other factors being equal, the more nonlinear the wave the greater the runup. Comparisons show that the formulas given make good estimates of the observed wave runup elevations.

Journal ArticleDOI
TL;DR: In this paper, an upper bound on the total energy of the wind wave spectrum in shallow water is extended to define a depth-controlled zero-moment wave height for irregular waves.
Abstract: A method for estimating an upperbound on the total energy of the wind wave spectrum in shallow water is extended to define a depth‐controlled zero‐moment wave height for irregular waves. The method requires an estimate of the peak frequency of the wave spectrum, knowledge of the Phillips' equilibrium coefficient, a, and water depth, h. A method for estimating α from the peak frequency of the sea spectrum and windspeed is given. Results indicate that the depth‐controlled zero‐moment wave height is generally less than the depth‐limited monochromatic wave height, Hd, and appears to vary with the square root of depth.

Journal ArticleDOI
TL;DR: In this article, an analytical model is developed to examine the response and efficiency of a rigid, hinged floating breakwater, and the theoretical model is verified experimentally and used to develop design curves which may be employed to estimate necessary physical breakwater characteristics to satisfy specified wave attenuation criteria.
Abstract: An analytical model is developed to examine the response and efficiency of a rigid, hinged floating breakwater. The theoretical model is verified experimentally and is used to develop design curves which may be employed to estimate necessary physical breakwater characteristics to satisfy specified wave attenuation criteria. The utility of these curves is demonstrated in a design problem. It is shown that a structure of reasonable size is an effective dynamic barrier for high frequency waves and an effective kinematic barrier for low frequency waves.

Journal ArticleDOI
TL;DR: In this paper, the authors show that the range between annual extremes at any station is only 0.4 feet (0.12m) with the highest tides predicted during the period 1986-1990, and that future astronomical components of extreme tides will exceed those of 1982-1983 by at most several tenths of a foot.
Abstract: When a combination of high tides and severe storm induced waves devastated California's coast in the winter of 1982-1983, predictions of much higher tides in the early 1990's appeared in the press. Standard harmonic tide predictions are prepared for San Diego, Los Angeles, San Francisco and Humboldt Bay extending until the year 2000. These show that the range between annual extremes at any station is only 0.4 foot (0.12m) with the highest tides predicted during the period 1986-1990. The predictions include: The semiannual beat of tide constituents which produce peak tides each summer and winter; a distinct 4.4 year beating which peaked during 1982-1983; and a peak enhancement of extreme tides in 1987 from maximum contributions of diurnal constituents due to the 18.61 year cycle in the longitude of the moon's node. Future astronomical components of extreme tides will exceed those of 1982-1983 by at most several tenths of a foot.

Journal ArticleDOI
TL;DR: In this paper, the shear stresses in saline wedges have been investigated in a 20 m long variable slope flume by the following approaches: (1) direct measurements of velocities and Reynolds stresses through hot film anemometers; (2) integration of the equations of motion; (3) Schijf-Schoenfeld's one-dimensional model; (4) Integration of the equation of motion assuming zero bed stress, which was found that the interfacial and bed friction coefficients, fi and fo, respectively, can best be correlated with the number ReFr2
Abstract: The shear stresses in saline wedges have been investigated in a 20 m long variable slope flume by the following approaches: (1) Direct measurements of velocities and Reynolds stresses through hot film anemometers; (2) integration of the equations of motion; (3) Schijf‐Schoenfeld's one‐dimensional model; (4) integration of the equations of motion assuming zero bed stress. It was found that the interfacial and bed friction coefficients, fi and fo, respectively, can best be correlated with the number ReFr2, in which Re is the Reynolds number, and Fr is the nondensimetric Froude number and with the relative density Δρ/ρ taken as an independent parameter. The results are given as a family of curves with each curve corresponding to a specific Δρ/ρ. The scattering of data is small and the agreement with results of earlier studies is good. Values of fi determined by the first two approaches agree closely, as do values obtained by the third and fourth approach. However the latter are substantially higher than the ...

Journal ArticleDOI
TL;DR: In this article, a model is developed to describe the turbidity plume induced by dredging a ship channel using an hydraulic dredge, which predicts the suspended sediment concentration within the plume and the resulting sediment deposition alongside the dredged channel.
Abstract: A model is developed to describe the turbidity plume induced by dredging a ship channel using an hydraulic dredge. The model predicts the suspended sediment concentration within the plume and the resulting sediment deposition alongside the dredged channel. The model applies to a dredging operation in a water body in which the current is primarily along the channel axis and the channel depth is large enough that no significant suspended sediment reaches water surface. Results of field measurements are presented and compared with model. It is shown that the model describes the qualitative feature of prototype data and that the calibrated model parameters agree with independent observations by other investigators.

Journal ArticleDOI
TL;DR: In this article, a numerical model describing wave-induced mean sea level variations and coastal currents in the nearshore region is developed by the finite element method, which includes nonlinear convective accelerations, lateral mixing and bottom friction.
Abstract: A numerical model describing wave‐induced mean sea level variations and coastal currents in the nearshore region is developed by the finite element method. The model includes nonlinear convective accelerations, lateral mixing and bottom friction. To specify the wave refraction field, a wave model is also developed with a semi‐discrete Galerkin method. The numerical accuracy of the model is verified with the analytic solutions for one‐dimenional longshore currents and two‐dimensional rip currents. The numerical model is also applied to predict realistic meandering currents occurring on a periodic rip channel. Due to the nonlinear inertial effect, the unaccelerated longshore current profile is stretched and causes a decrease in the magnitude of maximum velocity. A comparison with the analytic solution of a one‐dimensional longshore current velocity distribution indicates that the linear analytic solution significantly overestimates the maximum velocity. The numerical results quantitatively demonstrate the r...

Journal ArticleDOI
TL;DR: In this article, a mathematical model is developed to predict the flow characteristics in the downrush of regular waves and the critical condition for initiation of movement of armor units on the slope of a coastal structure.
Abstract: A mathematical model is developed to predict the flow characteristics in the downrush of regular waves and the critical condition for initiation of movement of armor units on the slope of a coastal structure. The analysis of water motion on the slope is based on the standing‐wave solution of the finite‐amplitude shallow‐water equations with an implicit account of the effects of wave breaking. This simple model neglects the effects of permeability, bottom friction and water depth. In addition, use is made of an empirical runup relationship. A stability analysis of armor units is performed including the drag, lift and inertia forces acting on an armor unit which vary along the slope with time over the period of wave downrush. Comparison is made with the largescale test data on riprap stability from an earlier study. The predicted critical stability number follows the same trend as the observed zero‐damage stability number, although the agreement is qualitative.

Journal ArticleDOI
TL;DR: In this article, a numerical model based on the parabolic approximation method is developed to calculate the wave characteristics in the nearshore region of the United States, and the model is developed for monochromatic linear waves and considers refraction, diffraction, and energy dissipation caused by the bottom turbulent boundary layer.
Abstract: A numerical model based on the parabolic approximation method is developed to calculate the wave characteristics in the nearshore region The model is developed for monochromatic linear waves and considers refraction, diffraction, and energy dissipation caused by the bottom turbulent boundary layer A numerical algorithm is also proposed to treat dignitized bathymetry data The accuracy of the present model is verified by comparing numerical results with two sets of field measurements collected by the Coastal Engineering Research Center along its research pier at Duck, North Carolina

Journal ArticleDOI
TL;DR: In this article, the effects of berm-type slopes on the stability of armor units and wave runup as compared to uniform slopes are investigated in a wave flume to investigate the effects.
Abstract: Riprap and sandbag model tests are conducted in a wave flume to investigate the effects of berm-type slopes on the stability of armor units and wave runup as compared to uniform slopes. Measurements of wave runup, rundown, wave height, breaker type and the response of armor units under regular wave action are made for each test run. The uniform and composite slope test results are analyzed using a modified Saville’s method which accounts for the overall effects of the slope configuration on the stability of armor units and wave runup. A simple analysis procedure based on the proposed method is developed for a preliminary design of a berm configuration. An example computation is made for a composite slope protected with riprap. The berm width, the berm slope and the water depth at the shallowest point of the berm are varied so as to determine the optimal berm configuration for increasing the stability of riprap under the assumed wave conditions.

Journal ArticleDOI
TL;DR: In this article, a method for representing the action of a seawall in the 1-line numerical model of shoreline evolution is presented, which involves restriction of the shoreline position and adjustment of the longshore sand transport rate so as to conserve sand volume and preserve direction of transport.
Abstract: A method is given for representing the action of a seawall in the 1-line numerical model of shoreline evolution. The method involves restriction of the shoreline position and adjustment of the longshore sand transport rate so as to conserve sand volume and preserve direction of transport. Sample calculations are presented, and the results are in accord with experience.

Journal ArticleDOI
TL;DR: In this paper, the authors derived an equation for the limiting wave height in the case of fully saturated wind seas in shallow water, which is very similar to the empirically derived expression obtained by Bretschneider in 1958.
Abstract: New developments in the area of shallow water wave spectra have aided in the derivation of an equation for the limiting wave height in the case of fully saturated wind seas in shallow water The result is very similar to the empirically derived expression obtained by Bretschneider in 1958 Starting with an equation for the depth controlled zero moment wave height in terms of depth, Phillip's coefficient, and the wave period associated with the peak spectral frequency, the result is obtained using a recently developed empirical experssion for the Phillip's coefficient and a method for specifying the peak spectral frequency at full development in shallow water The good comparison to Bretschneider's result is satisfying in that further validity is added to the basic equation used in the derivation and to the newer developments in shallow water spectral representations

Journal ArticleDOI
TL;DR: In this article, a time series of daily net longshore transport is estimated using the energy flux method, based upon measured Sxy, and from these, a number of statistics characterizing the degree of episodic transport are generated.
Abstract: Seven West Coast sites are selected having from one to three years of nearshore directional wave measurements several times a day during the period 1979–82. Time series of daily net longshore transport are estimated using the energy flux method, based upon measured Sxy. Investigations are made on frequency and cumulative distributions of transport, and from these, a number of statistics characterizing the degree of episodic transport are generated. The transport is found to be very episodic, with almost half of the gross transport occurring during only 10% of the time. The maximum transport occurring in a single day each year produced between ten times, and more than 600 times, the mean daily net transport. Inferences concerning the design requirements for sand bypass systems are drawn from the statistics of episodicity.