Aagaard, T., Infragravity Waves and Nearshore Bars in Protected, Storm- Dominated Coastal Environments, Marine Geology, 94 (3), 181-203, 1990.


Aagaard, T., N. Nielsen, and J. Nielsen, Cross-Shore Structure of Infragravity Standing-Wave Motion and Morphological Adjustment - an Example From Northern Zealand, Denmark, Journal of Coastal Research, 10 (3), 716-731, 1994.

A set of eight manometer tubes was deployed across a barred surf zone in Northern Zealand, Denmark in order to resolve the cross-shore structure of infragravity wave motions. During a storm, a single dominant standing infragravity wave was generated. This wave had a frequency similar to waves observed on previous occasions. Nearshore bars migrated 5-10 m landward (bar 1) and seaward (bar 2), respectively, with maximum accretion occurring close to the antinodes of the standing wave. The field data thus support theoretical models for bar formation and adjustment, according to which bars are generated through suspended sediment transport convergence at infragravity standing wave antinodes. The generation of the infragravity waves was investigated using bispectral analysis techniques. It was found that during the peak of the storm, two separate incident wave components transferred energy to the infragravity wave. As the storm waned, the incident wave components became further separated in frequency space. Simultaneously, the standing infragravity wave decayed.

Abadie, S., J.P. Caltagirone, and P. Watremez, Splash-up generation in a plunging breaker, Comptes Rendus De L Academie Des Sciences Serie Ii Fascicule B- Mecanique Physique Astronomie, 326 (9), 553-559, 1998.

We present in this paper a numerical method able to simulate the flow generated after the breaking of a wave. This latter is calculated by a direct solving of the incompressible Navier- Stokes equations involving two phases (water and air) associated with an accurate interface tracking algorithm. The whole method is validated on the case of permanent non linear wave propagation. A plunging breaking of a non-linear 'sinusoidal' wave is then simulated. The tracking of a 'marked' fluid volume standing in front of the wave before the impact allows us to find the origin of the fluid involved in the splash-up. This latter appears to be mainly composed of fluid particules which were initially in front of the wave.

Allen, J.R., N.P. Psuty, B.O. Bauer, and R.W.G. Carter, A field data assessment of contemporary models of beach cusp formation, Journal of Coastal Research, 12 (3), 622-629, 1996.

Cusp formation was observed during an instrumented, daily profiled, time series of a reflective beach in Canaveral National Seashore, Florida on January 5, 1988. The monitored cusp embayment formed by erosion of the foreshore and the cusp series had a mean spacing of approximately 28 m. During this time, inshore fluid flows were dominated by two standing edge waves at frequencies of 0.06 Hz (primary) and 0.035 Hz (secondary) whereas incident waves were broadbanded at 0.12- 0.16 Hz. Directly measured flows (and indirectly estimated swash excursion) data support both the standing wave subharmonic model (GUZA and INMAN, 1975) and the self- organization model (WERNER and FINK, 1993) of cusp formation in this study.

Baird, A.J., and D.P. Horn, Monitoring and modelling groundwater behaviour sandy beaches, Journal of Coastal Research, 12 (3), 630-640, 1996.

This paper reviews previous work on groundwater behaviour in sandy beaches. We consider the variations in beach watertables and moisture conditions above the watertable in relation to tidal and wave frequencies, and the relationship between beach groundwater, swash/backwash hydrodynamics and sediment transport. We note that most work on beach groundwater processes has tended to be empirical and argue that if understanding of beach groundwater/swash zone sediment transport interactions is to be improved, better measurement and physical representation of the relevant processes are needed, together with the formulation of physically-based models. We identify the form that future field monitoring programmes and models of beach groundwater processes could take.

Baldock, T.E., P. Holmes, and D.P. Horn, Low frequency swash motion induced by wave grouping, Coastal Engineering, 32 (2-3), 197-222, 1997.

This paper concerns the low frequency motion of swash directly induced by wave grouping on a steep beach. A new experimental investigation is presented which considers the hydrodynamics of the inner surf zone and swash zone using vertical wave gauges and a run-up wire. Results for regular waves, wave groups and random waves are discussed, with particular reference to low frequency motions. The inner surf zone and swash zone are found to be unsaturated at incident short wave frequencies and, as a result, significant wave grouping is apparent at the shoreline. The low frequency motion in the surf zone is found to be in phase with the incident wave grouping and may therefore be regarded as a time varying set-up (Watson and Peregrine, 1992). The low frequency motion of the swash is shown to be an order of magnitude greater than that in the inner surf zone, inconsistent with cross-shore standing long waves, for which no evidence is found. We demonstrate that the low frequency motion of the shoreline provides an excellent approximation to the run-up of individual bores and therefore describes the run-up envelope. Spectral analysis shows that the low frequency motion of the swash is directly linked to the modulations in offshore wave height, i.e. the low frequency energy in the incident wave envelope, In addition, the random wave run-up spectra show an f(-4) high frequency roll-off, as found by Huntley et al. (1977). The accumulated data show that, unless the surf zone is totally saturated, a significant proportion of the low frequency swash motion may be directly due to incident wave grouping and rot standing long waves. (C) 1997 Elsevier Science B.V.

Baldock, T.E., P. Holmes, S. Bunker, and P. Van Weert, Cross-shore hydrodynamics within an unsaturated surf zone, Coastal Engineering, 34 (3-4), 173-196, 1998.

This paper concerns the hydrodynamics induced by random waves incident on a steep beach. New experimental results are presented on surface elevation and kinematic probability density functions, cross-shore variation in wave heights, the fraction of broken waves and velocity moments. The surf zone is found to be unsaturated at incident wave frequencies, with a significant proportion of the incident wave energy remaining at the shoreline in the form of bores. Wave heights in both the outer and inner surf zones are best described by a full Rayleigh distribution [Thornton, E.B., Guza, R.T., 1983. Transformation of wave height distribution. J. Geophys. Res. 88, 5925-5938], rather than a truncated Rayleigh distribution as used by Battjes and Janssen (1978) [Battjes, J.A, Janssen, J.P., 1978. Energy loss and setup due to breaking of random waves. Proc. 16th Int. Conf. Coastal Eng. ASCE, New York, pp. 569-588]. A new parametric wave transformation model is outlined which provides explicit expressions for the fraction of broken waves and the energy dissipation rate within the surf zone. On steep beaches, the model appears to offer improved predictive capabilities over the original Battjes and Janssen model. Cross-shore variations in the velocity variance and velocity moments are best described using Linear Gaussian wave theory, with less than 20% of the velocity variance in the inner surf zone due to low frequency energy. (C) 1998 Elsevier Science B.V. All rights reserved.

Baldock, T.E., and P. Holmes, Simulation and prediction of swash oscillations on a steep beach, Coastal Engineering, 36 (3), 219-242, 1999.

This paper presents numerical simulations and analytical predictions of key aspects of swash oscillations on a steep beach. Simulations of the shoreline displacement based on bore run-up theory are found to give excellent agreement with recent experimental data for regular waves, wave groups and random waves. The theory is used to derive parameters that predict the onset of swash saturation and the spectral characteristics of the saturated shoreline motion. These parameters are again in good agreement with the measured laboratory data and are also consistent with previous experimental data. Simulation of irregular wave run-up using a series of overlapping monochromatic swash events is found to reproduce typical features of swash oscillations and can accurately describe both the low and high frequency spectral characteristics of the swash zone. In particular, the low frequency components of the run-up can be modelled directly using a sequence of incident short wave bores, with no direct long wave input to the numerical simulations. This suggests that wave groupiness must be accounted for when modelling shoreline oscillations. (C) 1999 Elsevier Science B.V. All rights reserved.

Baquerizo, A., M.A. Losada, J.M. Smith, and N. Kobayashi, Cross-shore variation of wave reflection from beaches, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 123 (5), 274-279, 1997.

The cross-shore variation of the local reflection coefficient R is examined under the assumptions of normally incident wind waves on beaches with alongshore uniform bathymetry. The existing three-gauge method is modified to estimate R for the sloping bottom. A new method is developed to estimate the incident and reflected root-mean-square (RMS) wave heights from the measured RMS wave height and wave setup. These methods are used to analyze six runs from the large-scale SUPERTANK data set. The estimated values of R are affected little by the formation of a bar and increase shoreward with the increased percentage of breaking waves. One set of the DELILAH field data on a barred beach is also analyzed using collocated pressure and velocity measurements. This data set confirms the negligible effect of the bat on the variation of R over the bar in the absence of wave-breaking on the bar crest. These crude estimates of R suggest that the reflected wind waves may not be negligibly small in comparison to the incident wind waves, especially inside the surf zone.

Battjes, J.A., Surf-Zone Dynamics, Annual Review of Fluid Mechanics, 20, 257-293, 1988.


Bauer, B.O., and B. Greenwood, Surf-Zone Similarity, Geographical Review, 78 (2), 137-147, 1988.


Bauer, B.O., and J.R. Allen, Beach Steps - an Evolutionary Perspective, Marine Geology, 123 (3-4), 143-166, 1995.

Field observation of contrasting beach-step behavior at Canaveral National Seashore on two subsequent days when incident-wave conditions in the inner surf zone were similar prompted this re-examination of our conceptual and quantitative understanding of beach steps. These lower-foreshore features are more complex than previously assumed, evolving through erosional as well as accretional phases, and displaying equifinality in geometric form but not necessarily internal sedimentary structure. Past and recent evidence is reviewed that links beach steps to incident waves at the surging- plunging transition and to the action of a backwash vortex. Tides and low-frequency waves likely play no direct role in beach-step initiation, although their presence can have pronounced influences on modulating nearshore hydrodynamics, and thus, on beach-step maintenance and evolution. A generalized, conceptual model capturing these aspects of beach- step dynamics is presented. Beach-step initiation proceeds via step ''carving'', ''excavation'', or ''building'' depending on the erosional-accretional character of the beach-foreshore system. Subsequent evolution of the step form may take one of several alternative morphodynamic pathways including step-face ''retreat'', step ''drag down'' or step ''infilling/elimination'' depending on tidal stage/range or wave set-up/set-down. Additional data on equilibrium beach-step forms and associated morphodynamic and hydrodynamic conditions in the field are necessary before quantitative models of beach- step existence and evolution can be formulated with realistic results.

Beji, S., and K. Nadaoka, A formal derivation and numerical modelling of the improved Boussinesq equations for varying depth, Ocean Engineering, 23 (8), 691-704, 1996.

A formal derivation of the improved Boussinesq equations of Madsen and Sorensen (1992) is presented to provide the correct forms of the depth-gradient related terms. Linear shoaling characteristics of the new equations are investigated by the method of Madsen and Sorensen (1992) and by the energy flux concept separately and found to agree perfectly, whereas these approaches give conflicting results for the equations derived by Madsen and Sorensen (1992). Furthermore, Nwogu's (1993) modified Boussinesq model is found to produce a linear shoaling-gradient identical with the present work. Numerical modelling of the derived equations for directional waves is carried out by three-time level finite-difference approximations. A higher-order radiation condition is implemented for effective absorption of the outgoing waves. Several test cases are included to demonstrate the performance of the model. Copyright (C) 1996 Elsevier Science Ltd

Beji, S., and K. Nadaoka, A time-dependent nonlinear mild-slope equation for water waves, Proceedings of the Royal Society of London Series a- Mathematical Physical and Engineering Sciences, 453 (1957), 319-332, 1997.

A weakly nonlinear and dispersive water wave equation, which in linearized form yields a new version of the time-dependent mild-slope equation of Smith & Sprinks (1975), is derived. The applicable spectral width of the new wave equation for random waves is found to be more satisfactory than that of Smith and Sprinks (1975). For very shallow depths the equation reduces to the combined form of Airy's nonlinear non-dispersive wave equations; if the lowest-order dispersion is retained it produces the combined form of Boussinesq's equations. In the deep-water limit the equation admits the second-order Stokes waves as analytical solutions. Furthermore, by introducing a right-moving coordinate transformation, the equation is recast into a unidirectional form, rendering the KdV equation in one limit while reproducing the second-order Stokes waves in the other.

Beji, S., and K. Nadaoka, Authors' reply to Discussion of Schaffer and Madsen on "A formal derivation and numerical modelling of the improved Boussinesq equations for varying depth" (Ocean Engineering, 25 (1998) 497-500), Ocean Engineering, 25 (7), 615-618, 1998.


Beji, S., and K. Nadaoka, A spectral model for unidirectional nonlinear wave propagation over arbitrary depths, Coastal Engineering, 36 (1), 1-16, 1999.

A weakly-nonlinear and dispersive wave equation recently developed by the authors is used for formulating a spectral- type unidirectional wave propagation model describing spectral transformations of narrow-band waves travelling over arbitrary depths. The essential characteristics of the model equation are recapitulated first and then the spectral domain representation in terms of spatially varying harmonic amplitudes is presented. The resulting evolution equations are used to simulate the experiments concerning harmonic generation in shallow water and nonlinear random wave transformations over a submerged bar. Furthermore, the spectral model predictions are compared with the field measurements in nearshore with satisfactory results. (C) 1999 Elsevier Science B.V. All rights reserved.

Bradford, S.F., Numerical simulation of surf zone dynamics, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 126 (1), 1-13, 2000.

A numerical model that solves the unsteady, incompressible, Navier-Stokes equations has been utilized to simulate monochromatic, spilling and plunging waves over a sloping bed. The volume of fluid technique is used to track the location of the highly complex, discontinuous free surface. The influence of wave boundary conditions and the order of accuracy of the numerical approximations on predictions of breaker height, location, and undertow has been examined. In addition, simulations with one and two equation turbulence models were evaluated and results were compared with laboratory measurements of mean water level, trough and crest heights, undertow, and mean turbulence kinetic energy in order to evaluate the applicability of each approach in computing surf zone dynamics. Details of the breaking wave properties are presented and discussed.

Brazeiro, A., and O. Defeo, Macroinfauna zonation in microtidal sandy beaches: Is it possible to identify patterns in such variable environments?, Estuarine Coastal and Shelf Science, 42 (4), 523-536, 1996.

Prior studies on sandy beach macroinfauna have been directed to elucidate generalizable zonation patterns. These studies, usually based on a reduced temporal scale (i.e. one sampling date), have often highlighted the discrepancies between their results and the classical, static zonation schemes. This paper demonstrates that snapshot studies might fail to obtain conclusive results about zonation patterns in microtidal sandy beaches, because these constitute dynamic environments subjected to many sources of uncertainty. For this purpose, a yearly study (February 1988-January 1989) of the macroinfauna was carried out on a dissipative beach on the Atlantic coast of Uruguay. An average zonation pattern with three main belts was recognized between the sand dunes and the lower levels of the swash zone when considering annual mean abundances. This pattern roughly matched traditional zonation schemes, whereas monthly patterns did not always fit them-with the exception of some species. Important spatial variability of the macroinfauna was observed, with aperiodic and seasonal components. The former was associated with unpredictable movements of tidal levels, with the macroinfauna changing its position, tracking the high water level. Concerning seasonal periodicity, the species tended to occupy the upper levels of their respective distribution areas during spring and summer, whereas in autumn and winter they inhabited the lower levels. The fact that faunal zones are dynamic, and track sea levels and seasons, diminishes the applicability of static traditional patterns. It was concluded that a yearly study is needed to give a more representative picture of the zonation patterns in microtidal sandy beaches. (C) 1996 Academic Press Limited

Brinchnielsen, U., and I.G. Jonsson, 4th Order Evolution-Equations and Stability Analysis For Stokes Waves On Arbitrary Water Depth, Wave Motion, 8 (5), 455-472, 1986.


Brinkkjaer, O., J.B. Christoffersen, and I.G. Jonsson, Irregular Wave Refraction Due to Current - Discussion, Journal of Hydraulic Engineering-Asce, 110 (12), 1871-1873, 1984.


Brocchini, M., and D.H. Peregrine, Integral flow properties of the swash zone and averaging, Journal of Fluid Mechanics, 317, 241-273, 1996.

The swash zone is that part of a beach over which the instantaneous shoreline moves back and forth as waves meet the shore, This zone is discussed using the nonlinear shallow water equations which are appropriate for gently sloping beaches. A weakly three-dimensional extension of the two-dimensional solution by Carrier & Greenspan (1958) of the shallow water equations for a wave reflecting on an inclined plane beach is developed and used to illustrate the ideas, Thereafter attention is given to integrated and averaged quantities, The mean shoreline might be defined in several ways, but for modelling purposes we find the lower boundary of the swash zone to be more useful. A set of equations obtained by integrating across the swash zone is investigated as a model for use as an alternative boundary condition for wave-resolving studies, Comparison with sample numerical computations illustrates that they are effective in modelling the dynamics of the swash zone and that a reasonable representation of swash zone hows may be obtained from the integrated variables. The longshore flow of water in the swash zone is in many ways similar to the Stokes' drift of propagating water waves. Further averaging is made over short waves to obtain results suitable as boundary conditions for longer period motions including the effect of incident short waves. In order to clearly present the work a few simplifications are made. The main result is that in addition to the kinematic type of boundary condition that occurs on a simple, e.g. rigid, boundary two further conditions are found in order that both the changing position of the swash zone boundary and the longshore flow in the swash zone may be determined. Models of the short waves both outside and inside the swash zone are needed to complete a full wave-averaged model; only brief indication is given of such modelling.

Brocchini, M., Eulerian and Lagrangian aspects of the longshore drift in the surf and swash zones, Journal of Geophysical Research-Oceans, 102 (C10), 23155-23168, 1997.

A theoretical study of the mean longshore mass flux and longshore drift velocities due to waves obliquely incident on a uniform sloping beach is presented. Analysis is performed using both Eulerian and Lagrangian representations of the flow. A number of results based on inviscid solutions are obtained concerning the mean longshore mass flux [M-y] inside the swash zone. Thus [M-y] depends on the parameters (wave amplitude, wave frequency, and wave number) of waves incident at a shoreline in a similar fashion to the dependence of the mass flux occurring between the crests and troughs of propagating waves on the same wave parameters. The mass flux depends on the square of the local wave amplitude, even for very steep waves which break before reaching the shoreline. A Lagrangian approach shows that particle paths are not closed even offshore of the breaking point and that "zigzag transport" is characteristic of Lagrangian particle paths in the two- dimensional horizontal flow seaward of the swash zone. The cross-shore profile of the longshore drift velocity is analyzed. Very weak longshore drift velocity characterizes the nonbreaking waves up to the swash zone. Onshore of the breaking point we find that the longshore drift velocity has a quasi- linear profile up to the maximum velocity reached near the shoreline. Effects of seabed friction are included in the computation of cross-shore profiles of the longshore drift velocity. A sensitivity analysis reveals that even for relatively small friction parameters (f approximate to 0.1), velocities inside the swash zone are greatly reduced. The reduction in longshore drift velocity is greater for the Lagrangian profile than for the Eulerian one, and for larger friction parameters (f greater than or equal to 0.1) the maximum longshore velocity moves toward the breaking point, where the friction effects are smaller. Finally, steady state profiles of the longshore drift velocities (Eulerian and Lagrangian) are computed.

Bryan, K.R., and A.J. Bowen, Edge wave trapping and amplification on barred beaches, Journal of Geophysical Research-Oceans, 101 (C3), 6543-6552, 1996.

Theoretical predictions show that edge waves may be trapped on bars, providing a possible mechanism for bar growth. Simple solutions to the linear shallow water equations reveal that bar trapping is controlled by the depth of the water over the bar h(bar) and the geometry of the inshore trough relative to the bar. For specific geometries, amplification over the bar approaches an order of magnitude or more as the phase speed approaches root gh(bar), where amplification is defined as the surface displacement over the bar relative to the surface displacement at the shoreline. The amplification increases with the cross-shore length scales of the profiles. The amplification is somewhat frequency dependent, generating stronger currents at the location of the bar in specific frequency ranges. Previous work showed that particular edge wave modes have the correct length scales to generate beach features such as bars and beach cusps, but field observations, notably, shoreline run-up data, frequently show no evidence of edge wave energy being concentrated at the appropriate frequencies. However, for bar-trapped modes, edge wave energy is concentrated at the location of the bar; therefore this edge wave energy will not necessarily be evident in shoreline measurements. Strong correlation exists between the energy distribution of the longshore component of the orbital velocity observed in data collected at Superduck, October 11, 1986, and the distribution expected for a white edge wave spectrum at the shoreline. This suggests that bar-trapped edge waves exist, in particular, at incident wave frequencies.

Butt, T., and P. Russell, Suspended sediment transport mechanisms in high-energy swash, Marine Geology, 161 (2-4), 361-375, 1999.

Measurements of suspended sediment concentration at three heights above the bed, and cross-shore velocity at a single height were obtained usings miniature optical backscatter sensors and a miniature electromagnetic current meter, from the swash-zone of a high-energy macrotidal dissipative beach. Time- series from relatively low (H-s approximate to 0.8 m) and high (H-s approximate to 2.2 m) energy conditions were chosen for analysis. Possible onshore and offshore sediment transport mechanisms are identified as (a) sudden offshore to onshore velocity transition and turbulence in the swash-front leading to subsequent onshore advection by the uprush, and (b) low- frequency high-velocity backwashes exceeding a certain threshold for sediment suspension. These mechanisms are related to the velocity field through skewness and asymmetry. An increase in negative infragravity skewness in high-energy conditions suggests a potential shift towards offshore net transport. Time-averaged vertical profiles of cross-share suspended sediment flux were calculated from the velocity and concentration time-series. These show a tendency towards offshore transport in high-energy conditions, particularly at low levels in the water column. The actual sediment fluxes are believed to be more offshore than those calculated. One reason for this discrepancy is the inability of the instruments to detect swash activity at very low levels in the water column. (C) 1999 Elsevier Science B.V. All rights reserved.

Chadwick, A.J., An Unsteady-Flow Bore Model For Sediment Transport in Broken Waves .1. the Development of the Numerical-Model, Proceedings of the Institution of Civil Engineers Part 2- Research and Theory, 91, 719-737, 1991.

The paper is concerned primarily with numerical model studies of unsteady flow in the surf and swash zones using bore propagation models, and the resulting longshore transport of coarse non-cohesive materials. The development of a new numerical model of oblique bores on beaches, coupled with a uniform flow field sediment transport equation, is described. This model estimates the instantaneous and period averaged values of longshore and on/offshore sediment transport across the surf and swash zones. It has the potential for wide application (without site specific calibration) in the determination of longshore transport of coarse beach materials and also could be used to predict beach plan form changes.

Chang, K.A., and P.L.F. Liu, Experimental investigation of turbulence generated by breaking waves in water of intermediate depth, Physics of Fluids, 11 (11), 3390-3400, 1999.

This paper reports a set of laboratory data for breaking waves in the water of intermediate depth. A monochromatic wave train with a wave height of 14.5 cm and a wavelength of 121 cm was generated in a water depth, h, of 20 cm. The wave train breaks consistently at a distance of about 2h from the wave generator. The instantaneous velocity fields under the breaking waves on a two-dimensional vertical plane were measured by using the particle image velocimetry (PIV) technique. By repeating the same experiments twenty times and performing the ensemble average, mean velocity, mean vorticity, turbulence intensity, and other flow properties such as the Reynolds stress and the mean strain rate were calculated. Outside the aerated region, where the density of air bubbles is high, the experimental data show that the mean vorticity was of the same order of magnitude as (C/h) (approximate to 6 s(-1)) with C being the phase speed. The maximum turbulence intensity outside the aerated region was in the order of magnitude of 0.1 C (approximate to 11 cm/s). The time-averaged (over one wave period) turbulence intensity under the wave trough level was one order of magnitude smaller, i.e., it was about 0.04 C (approximate to 4.8 cm/s). Based the experimental data, the transport equation for turbulent kinetic energy was further examined. The turbulence dissipation rate and its time scale were also estimated. Under the trough level at the measurement section, which was about 3h downstream from the breaking point, the turbulence production, and dissipation were of the same order of magnitude, but not identical. The turbulence advection, production, and dissipation were equally important, while the turbulence diffusion was almost negligible. (C) 1999 American Institute of Physics. [S1070- 6631(99)02211-4].

Chen, Y.Z., R.T. Guza, and S. Elgar, Modeling spectra of breaking surface waves in shallow water, Journal of Geophysical Research-Oceans, 102 (C11), 25035-25046, 1997.

Predictions from Boussinesq-equation-based models for the evolution of breaking surface gravity waves in shallow water are compared with field and laboratory observations. In the majority of the 10 cases investigated, the observed spectral evolution across the surf zone is modeled more accurately by a dissipation that increases at high frequency than by a frequency-independent dissipation. However, in each case the predicted spectra are qualitatively accurate for a wide range of frequency-dependent dissipations, apparently because preferential reduction of high-frequency energy (by dissipation that increases with increasing frequency) is largely compensated by increased nonlinear energy transfers to high frequencies. In contrast to the insensitivity of predicted spectral levels, model predictions of skewness and asymmetry (statistical measures of the wave shapes) are sensitive to the frequency dependence of the dissipation. The observed spatial evolution of skewness and asymmetry is predicted qualitatively well by the model with frequency-dependent dissipation, but ij predicted poorly with frequency-independent dissipation. Although the extension of the Boussinesq equations to breaking waves is ad hoc, a dissipation depending on the frequency squared (as previously suggested) reproduces well the observed evolution of wave frequency spectra, skewness, and asymmetry.

Chen, Q., J.T. Kirby, R.A. Dalrymple, A.B. Kennedy, and A. Chawla, Boussinesq modeling of wave transformation, breaking, and runup. II: 2D, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 126 (1), 48-56, 2000.

In this paper, we focus on the implementation and verification of an extended Boussinesq model for surf zone hydrodynamics in two horizontal dimensions. The lime-domain numerical model is based on the fully nonlinear Boussinesq equations. As described in Part I of this two-part paper, the energy dissipation due to wave breaking is modeled by introducing an eddy viscosity term into the momentum equations, with the viscosity strongly localized on the front face of the breaking waves. Wave runup on the beach is simulated using a permeable-seabed technique. We apply the model to simulate two laboratory experiments in large wave basins. They are wave transformation and breaking over a submerged circular shoal and solitary wave runup on a conical island. Satisfactory agreement is found between the numerical results and the laboratory measurements.

Cho, Y.S., and P.L.F. Liu, Crest-length effects in nearshore tsunami run-up around islands, Journal of Geophysical Research-Oceans, 104 (C4), 7907-7913, 1999.

The large run-up heights observed on the lee side of a circular island are investigated, using the shallow-water equations, to understand the devastating run-up heights reported in the lees of both Babi and Okushiri Islands during the Flores 1992 and the Hokkaido 1993 tsunamis. Specifically, the effects of the crest length of incident waves are examined both numerically and experimentally. It is found that the run-up heights around a circular island are strongly dependent on the crest length of incident waves when the crest length is less than the base diameter of the island but are almost insensitive if the crest length is greater than twice the base diameter. This observation implies that it may be possible to calculate a worst case scenario of run-up on an island from nearshore events.

Christoffersen, J.B., and I.G. Jonsson, An Energy Reference Line For Dissipative Water-Waves On a Current, Journal of Hydraulic Research, 19 (1), 1-27, 1981.


Christoffersen, J.B., and I.G. Jonsson, Bed Friction and Dissipation in a Combined Current and Wave Motion, Ocean Engineering, 12 (5), 387-423, 1985.


Contreras, H., O. Defeo, and E. Jaramillo, Life history of Emerita analoga (Stimpson) (Anomura, Hippidae) in a sandy beach of south central Chile, Estuarine Coastal and Shelf Science, 48 (1), 101-112, 1999.

Emerita analoga (Crustacea, Anomura, Hippidae) is a characteristic species of the swash zone of temperate sandy beaches of the Eastern Pacific. To analyse the reproductive biology and population dynamics of a population located in south central Chile, monthly samples were collected from an exposed sandy beach (Mehuin, c. 39 degrees S). Samples were taken from June 1989 through May 1991, and between June 1992 and May 1993, from the uppermost beach levels and the lowest: level of the swash zone. The highest abundances of E. analoga occurred during the late spring-early summer. The highest mean fecundity values occurred in winter and summer, and the lowest during spring. The size at which females reach sexual maturity was found to be 16-17 mm (about 12 months after recruitment). Two recruitment peaks were found: one during early autumn, and the other during spring. Growth analyses showed that growth rates of females were higher than those of males for the three annual periods analysed. It is concluded that differences in size at sexual maturity and in growth rates can explain sexual dimorphism in adult E. analoga in south central Chile. (C) 1999 Academic Press.

Cox, D.T., N. Kobayashi, and A. Okayasu, Bottom shear stress in the surf zone, Journal of Geophysical Research-Oceans, 101 (C6), 14337-14348, 1996.

To investigate the bottom shear stress in the surf zone, detailed laboratory measurements were made of the free surface elevations and velocities for the case of regular waves spilling on a rough, impermeable 1:35 slope. The velocity profiles were measured at several vertical lines in the cross- shore direction to include the shoaling region seaward of breaking, the break point, the transition region, and the inner surf zone. Each vertical line included measuring points at a fraction of the grain height above the rough, fixed bottom. A logarithmic layer was found to exist in the bottom boundary layer for most of the phases over a wave period seaward of the break point and in the surf zone. A regression analysis was used at each phase to estimate the shear velocity and bottom roughness from the phase-averaged horizontal velocities in the lower portion of the bottom boundary layer. The bottom friction factor was estimated from a quadratic friction equation based on the measured horizontal velocity above the bottom boundary layer together with the estimated shear velocity. The quadratic friction equation with the fitted friction factor was shown to predict the temporal variation of the bottom shear stress within a factor of 2. The bottom roughness estimated from the grain size assuming rough turbulent flow was shown to agree qualitatively with the measured values. The cross-shore variation of the friction factor estimated from an empirical formula developed for nonbreaking waves was shown to agree within a factor of 2 of the measured values.

CupulMagana, L.A., and M.A. TellezDuarte, Space-time variations in macrobenthic fauna of a sandy beach, related to changes in the beach profile and sediment grain size, at El Pelicano Beach, Baja California, Ciencias Marinas, 23 (4), 419-434, 1997.

Time-space variations in macrobenthonic biocenosis are described in relation to the morphology of the beach profile and textural characteristics of the sediment at El Pelicano Beach, south of San Felipe, Baja California, Mexico. Sampling was carried out in March, May, September and November 1993 along a beach profile, at fixed stations from the higher high tide to the lower low tide. Abundance data matrices were analyzed by applying a Q-mode cluster analysis, in order to establish community structural changes and compare them with changes in the beach profile and sediment grain size. In general, the number of species was consistently low and varied with the textural characteristics of the sediment and the morphology of the beach profile. Only the gastropod Nassarius iodes was dominant in all the samplings and beach profile levels, because of its tendency to follow the tide in order to remain in the swash zone where feeding conditions are optimum. Community structural changes at El Pelicano Beach indicate that the ecological and paleoecological interpretation of comparable coastal environments is complex, because of the biotic and abiotic time-space variability.

Curray, J.R., Origin of beach ridges: Comment, Marine Geology, 136 (1-2), 121-125, 1996.

Tanner (1995) has proposed that most common strand plain sandy beach ridges (his swash-built type) have been formed by a sea level rise-and-fall couplet of 5-30 cm, with a periodicity which is most commonly 30-60 years, but which ranges from as little as 3 to as much as 60 years. While such a mechanism could perhaps apply to beach ridges in lakes, if sea level has fluctuated with such regularity for the past several thousand years, all open ocean beach ridge periodicities should be the same, and furthermore this sea level signal would surely have been detected by physical oceanographers. Curray et al. (1969) described a strand plain of several hundred beach ridges on the western Mexican coast with cyclic formation of ridges varying from 12.2 to 16.5 years. The mechanism of formation invoked was periodic building of offshore bars to above sea level after sufficient sand had been transported into the area and during an optimal combination of oceanographic conditions.

Dodd, N., Numerical model of wave run-up, overtopping, and regeneration, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 124 (2), 73-81, 1998.

A numerical model of wave run-up, overtopping, and regeneration is presented. The model (called OTT) is based on the one- dimensional nonlinear shallow water equations on a sloping bed, including the effects of bed shear stress. These equations are solved using a finite-volume technique incorporating a Roe-type Riemann solver. The main advantage of this approach over previously used finite difference solvers is that no special shoreline-tracking algorithm is required, so that noncontiguous hows can easily be simulated. Hence, this model can be used to simulate the transmission of waves over water surface-piercing obstacles. The numerical scheme and boundary conditions are described, and several existing data sets used to test the ability of the model to simulate wave transformation, run-up, and overtopping. Experiments of random wave (unimodal and bimodal) overtopping, presented here for the first time, indicate that the model performs much better than empirical formulas in predicting average overtopping rates, and that it provides good estimates for the number of overtopping events. Experiments of overtopping of a sea wall by a solitary wave are also presented, including measurements of wave regeneration in lee of the dike. The model does a reasonable job of reproducing the water depths on top of the dike, and performs well in simulating the initial height of the regenerated waves.

Elgar, S., R.T. Guza, and M.H. Freilich, Observations of Nonlinear-Interactions in Directionally Spread Shoaling Surface Gravity-Waves, Journal of Geophysical Research-Oceans, 98 (C11), 20299-20305, 1993.

Shoaling wave fields generated in laboratory experiments were analyzed to determine the sensitivity of nonlinear interactions to the directional distributions of incident waves. Peaks in the directional spectra observed in shallow water were consistent with near-resonant, quadratic interactions between two primary waves transferring energy to a third wave with the sum frequency and vector sum wavenumber of the primary waves. Directionally colinear waves forced a higher-frequency wave propagating in the same direction as the primary waves, while directionally spread (i.e., noncolinear) primary waves forced a higher-frequency wave that propagated in a direction between those of the interacting primary waves. Deepwater wave fields with similar frequency spectra but different directional spectra evolved to different shallow-water directional spectra, yet their shallow-water frequency spectra were remarkably similar. This result suggests that the shape of the directional spectrum of the incident wave field has only a small effect on the magnitudes of nonlinear energy transfers during shoaling. The principal effect of directionality in the incident wave field is on the directions, not the amplitudes, of the nonlinearly generated waves. The laboratory data demonstrate clearly the importance of triad interactions between noncolinear and colinear shoaling waves.

Elgar, S., R.T. Guza, B. Raubenheimer, T.H.C. Herbers, and E.L. Gallagher, Spectral evolution of shoaling and breaking waves on a barred beach, Journal of Geophysical Research-Oceans, 102 (C7), 15797-15805, 1997.

Field observations and numerical model predictions are used to investigate the effects of nonlinear interactions, reflection, and dissipation on the evolution of surface gravity waves propagating across a barred beach. Nonlinear interactions resulted in a doubling of the number of wave crests when moderately energetic (about 0.8-m significant wave height), narrowband swell propagated without breaking across an 80-m- wide, nearly flat (2-m depth) section of beach between a small offshore sand bar and a steep (slope = 0.1) beach face, where the waves finally broke. These nonlinear energy transfers are accurately predicted by a model based on the nondissipative, unidirectional (i.e., reflection is. neglected) Boussinesq equations. For a lower-energy (wave height about 0.4 m) bimodal wave field, high-frequency seas dissipated in the surf zone; but lower-frequency swell partially reflected from the steep beach face, resulting in significant cross-shore modulation of swell energy. The combined effects of reflection from the beach face and dissipation across the sand bar and near the shoreline are described well by a bore propagation model based on the nondispersive nonlinear shallow water equations. Boussinesq model predictions on the flat section (where dissipation is weak) are improved by decomposing the wave field into seaward and shoreward propagating components. In more energetic (wave heights greater than 1 m) conditions, reflection is negligible, and the region of significant dissipation can extend well seaward of the sand bar. Differences between observed decreases in spectral levels and Boussinesq model predictions of nonlinear energy transfers are used to infer the spectrum pf breaking wave induced dissipation between adjacent measurement locations. The inferred dissipation rates typically increase with increasing frequency and are comparable in magnitude to the nonlinear energy transfer rates.

Ellers, O., Behavioral-Control of Swash-Riding in the Clam Donax-Variabilis, Biological Bulletin, 189 (2), 120-127, 1995.

Clams of the species Donax variabilis migrate shoreward during rising tides and seaward during falling tides. These clams spend most of the time in the sand, emerging several times per tidal cycle to ride waves. Migration is not merely a passive result of waves eroding clams out of the sand; rather clams actively jump out of the sand and ride specific waves. Such active migration is experimentally demonstrated during a falling tide by comparing the motion of dead and live clams; live clams emerge from the sand and move seaward even when dead ones do not. As low tide approaches, live clams become progressively less active. They cease migrating for 2 hours around low tide and resume jumping to migrate shoreward after the tide has turned. During the rising tide, far from being passive, the clams jump out to ride only the largest 20% of waves. Specifically, they choose swash that have the largest excursion, i.e., those swash that move furthest on the beach.

Ellers, O., Discrimination Among Wave-Generated Sounds By a Swash-Riding Clam, Biological Bulletin, 189 (2), 128-137, 1995.

Clams, Donax variabilis, responded to sound stimuli presented to them in a laboratory aquarium by jumping out of the sand, lying on the sand for several seconds, and digging in again. On a beach, clams jump out of the sand and ride waves, migrating shoreward with the rising tide and seaward with the falling tide. Parallels between clam behavior on a beach and that elicited in the laboratory suggest that clams cue on wave sounds to jump out of the sand. Three aspects of the response to sound were parallel. (i) Clams were most responsive to low- frequency sounds similar to those produced on a beach by waves rolling onto shore. (ii) Clams were also more responsive to louder sounds; on a beach, clams jump preferentially for the largest (loudest) 20% of waves. (iii) Responsiveness in the laboratory had an endogenous tidal rhythm, with highest activity occurring at high tide and no activity occurring at low tide; this rhythm corresponds to the activity of clams on the beach from which they were collected. By using sounds to identify large waves, clams can ride selected waves and continuously maintain position at the sea's edge as the tide floods and ebbs.

Ellers, O., Form and Motion of Donax-Variabilis in Flow, Biological Bulletin, 189 (2), 138-147, 1995.

The coquina clam, Donax variabilis, rides flow from waves, migrating shoreward during rising tides and seaward during falling tides. This method of locomotion, swash-riding, is controlled not only behaviorally but also morphologically. The shape of this clam causes it to orient passively; a clam rotates in flow, usually in backwash, until its anterior end is upstream. Rotation is about a vertical axis through a pivotal point where the shell touches the sand. The density, weight distribution, and wedge-like shape are all important in effecting orientation. Such orientation is significant because it contributes to stability of motion. On an unoriented clam, upward lift can be higher than its underwater weight-a circumstance that results in uncontrollable tumbling. In contrast, once oriented with its anterior end upstream, a clam experiences downward lift that contributes to its stability while sliding in backwash. Furthermore, when the anterior end is upstream, drag is reduced relative to when the ventral, dorsal, or posterior ends are upstream. Since orientation occurs only above a minimum velocity, it has the effect of slowing a clam's motion over the substratum in rapid flows. Stability, drag, and speed reduction enhance a clam's ability to gain a foothold and dig in after a swash-ride, before wave flows can wash it off the beach and out to sea.

Fletcher, C.H., B.M. Richmond, G.M. Barnes, and T.A. Schroeder, Marine Flooding On the Coast of Kauai During Hurricane Iniki - Hindcasting Inundation Components and Delineating Washover, Journal of Coastal Research, 11 (1), 188-204, 1995.

The right frontal quadrant of Hurricane Iniki crossed the southeast coast of Kaua'i on the afternoon of September 11, 1992 and produced marine overwash with excursion distances of approximately 20-250 m and elevations in the range 4-9 m (mllw). Using a combination of field data, empirical relationships, and theory, we estimate that the effective maximum sustained wind velocity (V-theta max) was in the range 52.4+/-2 m/s. We also analyze the meteorological and oceanographic components of marine flooding under the right frontal quadrant of the storm. Overwash was principally a function of eye-relative position and orientation of the coast, tan theta (slope), the friction-controlled wave run-up, and the wave set-up. Maximum overwash was adjacent to a major bathymetric channel and a slightly embayed coastline which reduced wave-energy dissipation in the nearshore, affording greater landward translation of deep-water wave characteristics. Total combined calculated overwash on the south shore of Kaua'i at Kukuiula (similar to 5.2 m mllw) is the sum of pressure set-up (0.39 m), wave set-up (1 m), wind stress set-up (0.06 m), run-up (2.9 m) and tidal stage (similar to 0.8 m). Measured debris-line and still-water mark elevations there ranged from 3.91-5.90 m (mllw). To the east on the steeper Koloa Landing coast, the calculated overwash components equaled approximately 6.6 m (mllw), and measured debris-line elevations ranged from 6.84 to 9.16 m (mllw). We present and discuss maps of the Iniki debris line relative to the FEMA V- zone and 100-yr flood zone, and major transportation arteries along the shoreline at five major coastal population centers on Kaua'i.

Foote, M., and D. Horn, Video measurement of swash zone hydrodynamics, Geomorphology, 29 (1-2), 59-76, 1999.

A new technique for recording two-dimensional uprush and backwash depth profiles using standard analogue camcorder technology is introduced. This technique has the potential to provide low cost, high frequency, high resolution measurements of individual swash events. Analogue to digital data conversion using multimedia software is discussed, as is the derivation of metric data via image processing and geographical information systems techniques. A series of field and laboratory experiments are described which provided an opportunity to refine and test the technique. Data from the laboratory video record are compared against measurements from standard surface piercing resistance type wave gauges, and an assessment made of the next steps required for the enhancement of the technique. The comparison between video and probe data indicates that the technique shows promise as a means of deriving two-dimensional profiles of swash lens; however, further development and testing are necessary. (C) 1999 Elsevier Science B.V. All rights reserved.

Forbes, D.L., J.D. Orford, R.W.G. Carter, J. Shaw, and S.C. Jennings, Morphodynamic Evolution, Self-Organization, and Instability of Coarse-Clastic Barriers On Paraglacial Coasts, Marine Geology, 126 (1-4), 63-85, 1995.

Beaches and barriers on many mid- to high-latitude coasts comprise mixtures of fine and coarse elastic materials forming a distinctive morphodynamic environment. In many cases, the sediments are derived primarily from limited glacigenic deposits and the coasts are considered paraglacial. Over relatively long time scales (decades to centuries), coarse- elastic barriers on such coasts show evidence of self- organisation through large-scale morphological evolution and facies differentiation. This process involves gradual reworking, partitioning, and textural sorting of material toward transport minima. Long intervals of slow evolution are punctuated by episodes of rapid reorganisation, involving breakdown of stable barrier structures and facies patterns, remixing of sediment, and accelerated migration of transgressive systems. Drift-aligned systems develop longshore cell structure, sometimes leading to breaching and segmentation, and may evolve toward progressively greater swash alignment under appropriate circumstances. Swash-aligned systems may experience catastrophic transformation when appropriate environmental triggers lead to threshold exceedance in the morphodynamics of the shore system. Adjacent barriers may show quite different behaviour, depending on the antecedent states of individual coastal cells. While appropriate parameterisations and sediment budget formulations allow us to model the long-term evolution of some barrier structures, the non-linear dynamics that appear to dominate large-scale behaviour may limit predictability. The identification of stability threshold criteria remains an important research priority.

Frihy, O.E., M.F. Lotfy, and P.D. Komar, Spatial Variations in Heavy Minerals and Patterns of Sediment Sorting Along the Nile Delta, Egypt, Sedimentary Geology, 97 (1-2), 33-41, 1995.

Sand samples were collected along 34 beach profiles spanning the 240-km length of the Nile Delta in order to examine the sorting patterns of heavy minerals that develop during cross- shore and alongshore sediment transport. Factor analysis of the heavy-mineral contents shows that two mineral factors or groups result from sorting due to the contrasting densities and sizes of the grains. One factor is dominated by augite, hornblende and epidote, while the second factor consists of opaques, garnet, zircon, rutile and monazite. Minerals of factor 1 are of lower densities and coarser sizes, and represent the grains that are selectively entrained by waves and currents in areas of beach erosion and preferentially transported to zones of beach accretion where they are deposited. The higher-density minerals of factor 2 tend to become concentrated in areas of beach erosion, accounting for the formation of black-sand placers where the erosion has been greatest. The spatial distributions of these two factors reflect the grain-sorting patterns of the heavy minerals which coincide with the general trends of shoreline erosion versus accretion that exist along the length of the delta. There is also a distinctive pattern of cross-shore sorting, with factor 2 containing the denser minerals being best developed within the inner surf zone, generally with a maximum at the shoreline. Its development corresponds to the formation of black-sand concentrates on the beach face where erosion has been greatest, implying that grain sorting has taken place mainly within the swash zone. There is a general decrease in factor 2 relative to factor 1 toward the offshore, often with oscillations that are congruent with the beach topography; factor 1 with the lower-density minerals is greatest over offshore bars where deposition has prevailed.

Frouin, P., C. Hily, and P. Hutchings, Ecology of spionid polychaetes in the swash zone of exposed beaches in Tahiti (French Polynesia), Comptes Rendus De L Academie Des Sciences Serie Iii-Sciences De La Vie-Life Sciences, 321 (1), 47-54, 1998.

The high-energy black sand beaches around the island of Tahiti show low species richness. Most of the individuals collected in the swash zone belong to two recently described species of polychaete Scolelepis sp. A, and Scolelepis sp. B (Spionidae). Densities of the first species can reach up to 1 900 individuals.m(-2) and biomasses up to 47.5 g dry weight (gD.W.).m(-2). These high densities and biomasses occur because of their adaptation to this high-energy habitat, where they are restricted to the swash zone on the beach. Scolelepis sp. A appears to be a suspension feeder and feeding occurs only as the wave recedes. This suggests that the species is highly efficient at obtaining nutrients in this oligotrophic environment. Scolelepis sp. B, sampled in one station, exhibits the same patterns as Scolepis sp. A. Only three other species are present in this environment; carnivores or suspension feeders, they occur in low densities(< 10 individuals.m(-2)). ((C) Academie des sciences/Elsevier, Paris.).

Gares, P.A., R. Beachley, and M. Lampe, Offshore sediment transport through a blowout at Coquina beach, Outer Banks, North Carolina, USA, Zeitschrift Fur Geomorphologie, 41 (1), 31-43, 1997.

Offshore aeolian sediment transport is increasingly recognized as playing an important role in the sediment budget of beach/dune systems. The purpose of this study is to quantify the amount of sediment moved offshore from the dune crest, through a foredune blowout and across the beach. The study was conducted at Coquina Beach in Cape Hatteras National Seashore, North Carolina, USA, a location with a shoreline azimuth of 10 degrees. Sediment traps mere deployed in several locations on the dune, in a blowout, and across the beach on April 19, 1994, January 20, 1995, and February 23, 1995 when the wind direction had azimuths of 230-260 degrees and speeds of 6-15 m s(-1). The highest rates of sediment transport occurred on the unvegetated parts of the blowout rim, at the mouth of the blowout, and on the beach berm. The blowout redirected sediment transport along the base of the dune north of the blowout in a shore parallel direction. Sediment transport was lower at the landward end of the blowout throat and on the back beach between the dune and the berm. Sediment transport diminished noticeably between the berm crest and the swash line because of the moisture content of the beach sediments. The sediment transport patterns suggest that blowouts play an important role in the removal of sediment from a dune system during offshore winds and that they are partially responsible for variation in aeolian sediment transport across the beach.

Gimenez, L., and B. Yannicelli, Variability of zonation patterns in temperate microtidal Uruguayan beaches with different morphodynamic types, Marine Ecology-Progress Series, 160, 197-207, 1997.

Early studies on sandy beach zonation patterns have shown rather rigid schemes. Recent work has suggested that zonation changes with morphodynamic type and, in dissipative beaches, it also changes through time. This last finding leads to the conclusion that at least 1 yr of study is necessary to understand zonation patterns in dissipative sandy beaches. Here we report a 1 yr study (from March 1994 to March 1995) of 4 microtidal beaches with different morphodynamic types situated on the Atlantic coast of Uruguay. We show that zonation patterns (number of zones or belts) can change through time regardless of beach type. However, the morphodynamic characteristics of the beach seem to affect how frequently the zonation pattern can change by fusion or subdivision of zones, and which zones are involved in those processes. In beaches with flat slopes (toward the dissipative extremity), the lower zones were frequently fused and divided. The same occurred with the medium and upper zones in the beaches with steeper slopes (towards the reflective extremity). Our results suggest that spatial variability of the macrofauna is related to variability in the position of the swash zone, which in turn depends on beach slope and width. Variability of species distribution would also depend on morphological adaptations of organisms to move in such environments. We suggest 2 mechanisms of species movement to explain the variability in species distribution observed in this study: Swash Mediated Active Movement (SMAM) and Autonomous Active Movement (AAM). The first mechanism involves both an active and a passive component. AAM is independent of swash movements and affects species distribution on the upper levels of the beach.

Grilli, S.T., M.A. Losada, and F. Martin, Characteristics of Solitary Wave Breaking Induced By Breakwaters, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 120 (1), 74-92, 1994.

Laboratory experiments are presented for the breaking of solitary waves over breakwaters. A variety of behaviors is observed, depending on both breakwater and incident wave height: for emerged breakwaters, waves may collapse over the crown, or break backward during rundown; and for submerged breakwaters, waves may break forward or backward, downstream of the breakwater. The limit of overtopping and wave transmission and reflection coefficients are experimentally determined. It is seen that transmission is large over submerged breakwaters (55-90%), and may also reach 20-40% over emerged breakwaters. Computations using a fully nonlinear potential model agree well with experimental results for the submerged breakwaters, particularly for the smaller waves (H/d < 0.4). For emerged breakwaters, computations correctly predict the limit of overtopping, and the backward collapsing during rundown.

Grilli, S.T., R. Subramanya, I.A. Svendsen, and J. Veeramony, Shoaling of Solitary Waves On Plane Beaches, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 120 (6), 609-628, 1994.

Shoaling of solitary waves on both gentle (1:35) and steeper slopes (less-than-or-equal-to 1:6.50) is analyzed up to breaking using both a fully nonlinear wave model and high- accuracy laboratory experiments. For the mildest slope, close agreement is obtained between both approaches up to breaking, where waves become very asymmetric and breaking indices reach almost twice the value for the largest stable symmetric wave. Bottom friction does not seem to affect the results at all. Wave celerity decreases during shoaling and slightly increases before breaking. At breaking, the crest particle velocity is almost horizontal and reaches 90% of the crest celerity, which is two to three times larger than the bottom velocity. The nonlinear shallow water (NSW) equations and the Boussinesq approximation both fail to predict these results. Finally, shoaling rates for various wave heights and bottom slopes differ from the predictions of Green's or Boussinesq shoaling laws. On the mildest slope, shoaling rates roughly follow a ''two-zone'' model proposed earlier but on steeper slopes reflection becomes significant and wave heights change little during shoaling.

Hamilton, N.T.M., and L.B. Collins, Placer formation in a Holocene barrier system, southwestern Australia, Journal of Coastal Research, 14 (1), 240-255, 1998.

The location of coastal titanium-zirconium placers within coastal barrier sequences provides significant problems for traditional exploration model development, because of the geomorphic (as opposed to geologic) nature of the processes responsible for placer formation. This paper describes an economic placer at Minninup, southwestern Australia, and develops a model of formation from a geomorphic viewpoint. The Minninup placer deposits lie on the contemporary coast about 160 km south of Perth, Western Australia. The sediments form part of a Late Holocene transgressive barrier sequence, with placer development occurring in transgressive dune, elevated Mid Holocene beach and nearshore units, as well as contemporary environments. Sea-level history is a significant factor in placer development and preservation. Formation of the Minninup placers is the result of processes operating at different temporal and spatial scales. Heavy mineral segregation due to differential entrainment in the nearshore and swash zones, differential transport, shear sorting, and longshore and offshore sediment movement all contribute to concentration and preservation. Seasonal variation in wave energy and direction, coastal morphology, and barrier evolution are also crucial. A model, based on geomorphological concepts, showing how these factors interact to produce economic placers, reveals the value of alternative approaches to exploration model development.

Hamm, L., P.A. Madsen, and D.H. Peregrine, Wave Transformation in the Nearshore Zone - a Review, Coastal Engineering, 21 (1-3), 5-39, 1993.

This paper reviews works related to nearshore wave propagation with an emphasis on several aspects related to coastal morphodynamic modelling including randomness and directionality of waves, energy transfer and dissipation in the surf zone, shallow water non linearities and long period motions. The first part briefly reviews four main issues in laboratory experiments and field campaigns. The second part is devoted to spectral and probabilistic approaches. Then, recent developments of advanced numerical models based on Boussinesq equations are reviewed. The last part is devoted to low frequency waves and vortical motions.

Hegge, B.J., and G. Masselink, Spectral analysis of geomorphic time series: Auto-spectrum, Earth Surface Processes and Landforms, 21 (11), 1021-1040, 1996.

The collection of time series data is an essential component in the investigation of earth surface processes. Spectral analysis of these time series can provide an invaluable insight into the behaviour of geophysical processes. Spectral analysis of a single time series produces an auto-spectrum which provides a representation of the amount variance of the time series as a function of frequency. Prior to spectral analysis, the time series should be plotted to identify the presence of any trends in the mean or the variance of the series, and to identify anomalies in the data which should be corrected. To satisfy the assumption of stationarity, any trend (in either the mean or variance) should be removed from the time series. Consequently, the probability density function of the time series should be plotted and compared with the Gaussian distribution. The final stage in preparing the time series for spectral analysis is to apply a taper to reduce spectral leakage and distortion of the auto-spectrum. Following the calculation of the periodogram, spectral estimates should be combined to reduce the variability associated with the estimates and thereby ensure that the autospectrum is more representative. Finally, confidence limits should be constructed around the spectral density function so that statistically significant spectral peaks (or troughs) can be identified.

Herbers, T.H.C., S. Elgar, R.T. Guza, and W.C. Oreilly, Infragravity-Frequency (0.005-0.05 Hz) Motions On the Shelf .2. Free Waves, Journal of Physical Oceanography, 25 (6), 1063-1079, 1995.

In Part I, the energy levels of ocean surface waves at infragravity frequencies (nominally 0.005-0.05 Hz) locally forced by swell in 13-m water depth were shown to be predicted accurately by second-order nonlinear wave theory. However, forced infragravity waves were consistently much less energetic than free infragravity waves. Here, in Part II, observations in depths between 8 and 204 m, on Atlantic and Pacific shelves, are used to investigate the sources and variability of free infragravity wave energy. Both free and forced infragravity energy levels generally increase with increasing swell energy and decreasing water depth, but their dependencies are markedly different. Although free waves usually dominate the infragravity frequency band, forced waves contribute a significant fraction of the total infragravity energy with high energy swell and/or in very shallow water. The observed h(-1) variation of free infragravity energy with increasing water depth h is stronger than the h(-1/2) dependence predicted for leaky surface gravity waves propagating approximately perpendicular to local depth contours, but is consistent with a heuristic, geometrical optics-based (WKB) model of the refractive trapping of a directionally broad wave field generated close to shore. Preliminary analysis shows that free infragravity waves are indeed directionally broad and that the propagation directions of infragravity waves and incident swell are related. Free infragravity energy levels also depend on the general geographic surroundings. Comparisons of observations from the same depth and with similar swell conditions, but on different shelves, suggest that more free infragravity wave energy is radiated from wide, sandy beaches than from rocky, cliffed coasts and that less energy is trapped on a narrow shelf than on a wide shelf.

Herbers, T.H.C., S. Elgar, and R.T. Guza, Directional spreading of waves in the nearshore, Journal of Geophysical Research-Oceans, 104 (C4), 7683-7693, 1999.

Observations of surface gravity waves shoaling between 8-m water depth and the shoreline on a barred beach indicate that breaking results in an increase in the directional spread of wave energy, in contrast to the directional narrowing with decreasing depth predicted by refraction theory (Snell's law). During low-energy wave conditions, when breaking-induced wave energy losses over the instrumented transect are small, the observed mean propagation direction and spread about the mean both decrease with decreasing depth, consistent with the expected effects of refraction. Nonlinearity causes high- frequency components of the spectrum to become directionally aligned with the dominant incident waves. During high-energy wave conditions with significant wave breaking on the sand bar, the observed mean directions still decrease with decreasing depth. However, the observed directional spreads increase sharply (nominally a factor of 2 for values integrated over the swell-sea frequency range) between the outer edge of the surf zone and the crest of the sand bar, followed by a decrease toward the shoreline. Observations on a nonbarred beach also show directional broadening, with spreads increasing monotonically from the outer edge of the surf zone to a maximum value near the shoreline. Although the mechanism is not understood, these spatial patterns of directional broadening suggest that wave breaking causes significant scattering of incident wave energy into obliquely propagating components.

Holland, K.T., B. Raubenheimer, R.T. Guza, and R.A. Holman, Runup Kinematics On a Natural Beach, Journal of Geophysical Research-Oceans, 100 (C3), 4985-4993, 1995.

Runup kinematics on a gently sloping natural beach are examined with detailed measurements from video images, resistance wires deployed at five elevations (between 5 and 25 cm) above and parallel to the beach face, and pressure sensors located in the inner surf zone. As suggested in a previous study comparing a single-level resistance wire and manually digitized films, runup measurements are sensitive to the sensor elevation above the bed, owing to the elongated shape of the runup tongue. The measured mean runup elevation (setup) and vertical excursion increase as the sensor elevation decreases, with the video- based runup estimates having the maximum means and variances. For the six data runs the average ratios of the video-based setup and significant runup excursion to estimates based on wires elevated 15 cm above the bed are 2.7 and 1.5, respectively. These trends, combined with the high coherence and small phase difference between the video and the lowest wire, demonstrate that the video-based estimates correspond to a very near-bed (less than a few centimeters elevation) wire measurement. The measured increase in runup excursion with decreasing sensor elevation and the cross-shore variation in the amplitudes of pressure fluctuations at infragravity frequencies, are consistent with the theory for linear, inviscid, normally incident standing waves. For example, valleys in the pressure spectra occur at approximately the predicted standing wave nodal frequencies. Also in accord with small-amplitude wave theory, observed swash excursions are nearly identical to pressure fluctuations at the location of the measured runup mean (for pressure sensors located seaward of the most offshore bed-level rundown). However, at very low frequencies, where reflection is typically assumed complete and dissipation negligible, the observed, near-bed swash magnitudes are overamplified relative to a best fit of the linear standing wave model based on the amplitude and phase of the seaward observations.

Holland, K.T., and R.A. Holman, Field observations of beach cusps and swash motions, Marine Geology, 134 (1-2), 77-93, 1996.

We tested the hypothesis of cusp formation by the longshore structure of synchronous or subharmonic, mode-zero edge waves using detailed field measurements of foreshore topography, incident waves and swash motions. Two distinct intervals of cusp formation were observed. Alongshore separated swash measurements were analyzed to detect structures at wavelengths and frequencies consistent with the measured cusp spacings. For both events, no statistical support for cusp generation by the traditional subharmonic or synchronous edge wave mechanisms was found. However, once cusps became well developed, there was evidence of interaction between fluids and topography at a wavelength equal to the cusp spacing, but at the period of the incident swash. We propose that this interaction could have been responsible for the generation of the second set of cusps with a spacing of half the pre-existing cusp wavelength.

Holland, K.T., and R.A. Holman, Video estimation of foreshore topography using trinocular stereo, Journal of Coastal Research, 13 (1), 81-87, 1997.

Previous researchers have shown that topographic response to swash processes is typically rapid and occasionally substantial. However, the methods used to document these fluctuations were often labor intensive and usually resulted in only a few estimates at a limited number of survey locations. We present an automated technique for the detection of small- and large-scale variations in foreshore topography that has both high spatial and temporal resolution. This technique utilizes trinocular (three view) stereogrammetry to recover topographic information from a set of synchronous, overlapping video images. The foreshore topography is mapped by following the movement of the sharply defined foamy runup edge that visibly contrasts with the darker, underlying, saturated beachface. Under field test conditions, the video method has a vertical accuracy of between 1 and 3 cm, comparable to that of traditional surveying methods and to theoretical expectations. The advantages of this new technique are that the topography estimates are extremely dense, on the order of thousands of estimates within a 100 m(2) region, that estimates can be made on a wave by wave basis, and that sampling requires minimal manpower. This method may prove useful in the study of rapid foreshore sediment transport dynamics, such as the formation of beach cusps.

Holland, K.T., Beach cusp formation and spacings at Duck, USA, Continental Shelf Research, 18 (10), 1081-1098, 1998.

Approximately nine years of daily video images from Duck, NC, USA, were analyzed to determine the timing of cusp formation in relation to environmental forcing and the distances separating consecutive cusp horns. 57 independent cusp events (defined as transitions from visibly smooth to cuspate topography) were observed with most of the cusps forming after storms. The temporal lag between the peak in storm intensity and cusp development was typically 3 days. Approximately half of the cusp events had formations predicted by an empirical threshold relating storm presence, breaker angle, and beach reflectivity. This threshold and other statistical observations suggest that Duck cusps form as energy conditions become more reflective, as the offshore wave angle approaches normal incidence and as the directional spread of the incident wave field becomes narrower. The standard deviation of the observed spacings relative to the mean spacing for each event was around 15% with the range in spacings for each event being typically less than half the event's mean cusp width. There were no strong statistical relationships between mean cusp spacings and environmental parameters (such as swash excursion lengths). Copyright (C) 1998 Elsevier Science Ltd. All rights reserved.

Holland, K.T., and R.A. Holman, Wavenumber-frequency structure of infragravity swash motions, Journal of Geophysical Research-Oceans, 104 (C6), 13479-13488, 1999.

Alongshore-separated time series of natural swash motions were obtained over a range of environmental conditions using a video technique. Although the frequency spectra and normalized wavenumber spectra for these motions were particularly bland, wavenumber-frequency spectra of these data showed clear partitions of infragravity band energy levels associated with various wave types. For the frequencies 0.025 < f less than or equal to 0.05 Hz, 45 +/- 13% of the shoreline variance was, on average, associated with high-mode (n greater than or equal to 2) edge waves and/or leaky waves, while approximately half that amount was associated with low-mode edge waves. Gravity wave motions (comprising both edge and leaky modes) were typically dominant in a lower-frequency band (0.001 < f less than or equal to 0.025 Hz). A substantial portion of the variance in this band (21 +/- 10%, with a maximum of 38%), however, was identified as a nondispersive waveform with wavenumbers well outside of the wavenumber-frequency bounds for gravity waves. Surprisingly: this nongravity swash variance showed no significant dependence on mean alongshore current strength or mean alongshore current sheer as measured in the surf zone trough separating the shoreline from an offshore bar. In addition, the celerities of these swash zone nondispersive waves were found to differ in magnitude, and in one instance, sign, from celerities of similarly structured waves measured farther offshore in the surf zone. These unexpected observations with respect to low-frequency, nongravity swash energy imply a strong decorrelation between trough and shoreline fluid motions.

Holman, R.A., Extreme Value Statistics For Wave Run-Up On a Natural Beach, Coastal Engineering, 9 (6), 527-544, 1986.


Horn, D.P., and T. Mason, Swash Zone Sediment Transport Modes, Marine Geology, 120 (3-4), 309-325, 1994.

The result of field experiments, designed to investigate the relative proportions of bedload and suspended load, are described. The ratio of bedload to suspended sediment load in the swash zone is examined in both swash and backwash on four beaches by measuring the amounts collected in a sediment trap. Bedload transport is found to dominate the backwash. The relative proportions of bedload and suspended load change over the tidal cycle, with increasing bedload dominance at low tide. The total amount of sediment transported as swash and backwash is noticeably greater at high tide than at low tide. More sediment is transported on the flood tide than on the ebb.

Horn, D.P., Beach research in the 1990s, Progress in Physical Geography, 21 (3), 454-470, 1997.


Horn, D.P., Synergy and co-operation: collaborative coastal research projects, Progress in Physical Geography, 23 (1), 115-133, 1999.


Howd, P.A., A.J. Bowen, and R.A. Holman, Edge Waves in the Presence of Strong Longshore Currents, Journal of Geophysical Research-Oceans, 97 (C7), 11357-11371, 1992.

A form of the linear, inviscid shallow water wave equation which includes alongshore uniform, but cross-shore variable, longshore currents and bathymetry is presented. This formulation provides a continuum between gravity waves (either leaky or edge waves) on a longshore current, and the recently discovered shear waves. In this paper we will concentrate on gravity wave solutions for which V(x)/c < 1, where V(x) is the longshore current, and c is the edge wave celerity. The effects of the current can be uniquely accounted for in terms of a modification to the true beach profile, h'(x) = h(x) [1 - V(x)/C]-2, where h(x) is the true profile and h'(x) is the effective profile. This is particularly useful in conceptualizing the combined effects of longshore currents and variable bottom topography. We have solved numerically for the dispersion relationship and the cross-shore shapes of edge waves on a plane beach under a range of current conditions. Changes to the edge wave alongshore wavenumber, kappa, of over 50% are found for reasonable current profiles, showing that the departure from plane beach dispersion due to longshore currents can be of the same order as the effect of introducing nonplanar topography. These changes are not symmetric as they are for profile changes; \kappa\ increases for edge waves opposing the current flow (a shallower effective profile), but decreases for those coincident with the flow (a deeper effective profile). The cross-shore structure of the edge waves is also strongly modified. As \kappa\ increases (decreases), the nodal structure shifts landward (seaward) from the positions found on the test beach in the absence of a current. In addition, the predicted variances away from the nodes, particularly for the alongshore component of edge wave orbital velocity, may change dramatically from the no-current case. Many of the edge wave responses are related to the ratio V(max)/c, where V(max) is the maximum current, and to the dimensionless cross-shore scale of the current, \kappa\x(V(max), where x(V(max) is the cross- shore distance to V(max). This is most easily understood in terms of the effective profile and the strong dependence of the edge waves on the details of the inner part of the beach profile. Inclusion of the longshore current also has implications regarding the role of edge waves in the generation of nearshore morphology. For example, in the absence of a current, two phase-locked edge waves of equal frequency and mode progressing in opposite directions are expected to produce a crescentic bar. However, in the presence of a current, the wavenumbers would differ, stretching the expected crescentic bar into a welded bar. A more interesting effect is the possibility that modifications to the edge waves due to the presence of a virtual bar in the effective profile could lead to the development of a real sand bar on the true profile. These modifications appear to be only weakly sensitive to frequency, in contrast to the relatively strong dependence of the traditional model of sand bar generation at infragravity wave nodes.

Hughes, M.G., Friction Factors For Wave Uprush, Journal of Coastal Research, 11 (4), 1089-1098, 1995.

The non-linear shallow water theory contains a set of solutions for the problem of swash following bore collapse on a hydraulically smooth and impermeable beach. These have recently been compared with held data from a number of natural sandy beaches (HUGHES, 1992). The comparison between the inviscid equations and the data was generally favourable; however, the parameters measured were consistently over-predicted by the theory. It is assumed here that this discrepancy is due to energy dissipation effects not originally represented in the theory. The inviscid equation of motion for the shoreline following bore collapse is expanded to include a shear stress term to account for bed friction. This equation is then solved for the time-history of the shoreline position and the maximum swash height. Weld measurements of the maximum awash height, initial shoreline velocity, swash depth, beach slope and grain size are used with these equations to determine the inferred friction factor for the uprush. The magnitude of the friction factor is found to be of the order of 0.1 for the sandy beaches considered here. A recent model for the bottom boundary layer in the presence of sheet dow is capable of predicting the magnitude of the observed friction factor.

Hughes, M.G., G. Masselink, and R.W. Brander, Flow velocity and sediment transport in the swash zone of a steep beach, Marine Geology, 138 (1-2), 91-103, 1997.

Detailed measurements of flow velocity and total sediment load were obtained in the swash zone on a steep beach. Swash motion was measured using ducted impeller how meters and capacitance water level probes. During wave uprush, the onshore flow increased almost instantaneously from zero to its maximum velocity after the arrival of the leading edge of the swash lens and subsequently decreased gradually to zero for the remainder of the uprush. During backwash, the offshore how increased steadily from zero to its maximum towards the end of the backwash and dropped rapidly to zero as the beach fell ''dry''. The duration of backwash was typically longer than that of uprush and maximum water depth on the beach was attained just prior to the end of the uprush. The total sediment load was measured for 35 individual wave uprush events using a sediment trap. The amount of sediment transported by a single uprush was typically two to three orders of magnitude greater than the net transport per swash cycle (difference between uprush and backwash) inferred from surveys of beach profile change. The measured immersed weight total load transport rate displayed a strong relationship with the time- averaged velocity cubed, which is consistent with equations for both bedload transport and total load transport under sheet flow conditions. The Bagnold (1963, 1966) bedload transport model was tested against our field data and yielded I-b=ku(- 3)T(u)/(tan phi+tan beta), where I-b is the immersed weight of bedload transported during the entire uprush (kg m(-1)), k is a coefficient (kg m(-4) s(2)), (u) over bar is the time-averaged flow velocity for the uprush (m s(-1)), T-u is the uprush duration (s), phi is the friction angle of the sediment and beta is the beach slope. The empirically determined value for the coefficient k was 1.37+/-0.17. (C) 1997 Elsevier Science B.V.

Hughes, M.G., G. Masselink, and R.W. Brander, Flow velocity and sediment transport in the swash zone of a steep beach (vol 138, pg 91, 1997), Marine Geology, 145 (1-2), 149-149, 1998.


Inman, D.L., and R.T. Guza, The Origin of Swash Cusps On Beaches, Marine Geology, 49 (1-2), 133-148, 1982.


James, R.J., and P.G. Fairweather, Spatial variation of intertidal macrofauna on a sandy ocean beach in Australia, Estuarine Coastal and Shelf Science, 43 (1), 81-107, 1996.

Spatial variation of macrofauna on a sandy beach was examined simultaneously over two scales across-shore (among and within zones) and three nested scales along-shore over the entire length of the beach. Prior to the main study, pilot studies were performed to determine: (1) the relative efficiency, accuracy and precision of combinations of core size, depth of sampling, and sieve mesh size; and (2) the likely distribution of macrofauna across-shore so that stratification of sampling in the main study would be meaningful. From this, three zones were defined across-shore, namely: (1) the high-shore zone which extended 10 m downshore of the drift line and was dominated by two species of isopod; (2) the mid-shore zone which extended across the beach from the bottom of the high- shore zone to the top of the swash zone and was dominated by the glycerid polychaete Hemipodus sp.; and (3) the swash zone which contained more species than the other two zones and was dominated by amphipods, Hemipodus sp., the bivalve Donax deltoides and a species of cumacean. In the main study, multivariate analyses confirmed that assemblages of macrofauna varied significantly among zones despite smaller scale variation within zones and along-shore variation. Significant along-shore variation was detected in assemblages of macrofauna from each zone and occurred at different scales for different zones. Only assemblages in the swash zone showed a pattern of along-shore variation that was consistent with a gradient in wave exposure along the beach. Univariate analyses showed that significant variation in populations of individual taxa occurred at both large and small scales. Significant variation was detected across-shore within zones for nearly all variates and this demonstrated the importance of formally assessing variation within zones when making comparisons among zones. Significant variation was also detected along-shore in analyses of particular taxa, and interactions of across- and along-shore variation also occurred. These results illustrate the necessity of considering both across- and along-shore variation for describing spatial patterns in assemblages or individual species of macrofauna. Unfortunately, sampling a single transect across a beach, which is common in many published descriptions of spatial patterns, will not provide an adequate nor representative description of the macrofauna of that beach because this approach fails to consider all important sources of variation and confounds large- and small-scale variation. The authors conclude that a better understanding of small-scale variation, both along- and across-shore within beaches, is required in order to provide better descriptions of patterns, provide a basis for larger scale studies, allow unconfounded comparisons among beaches and, ultimately, to improve our understanding of the ecology of sandy beaches. (C) 1996 Academic Press Limited

Jaramillo, E., R. Stead, P. Quijon, H. Contreras, and M. Gonzalez, Temporal variability of the sand beach macroinfauna in south- central Chile, Revista Chilena De Historia Natural, 69 (4), 641-653, 1996.

Two sandy beaches were studied in south - central Chile (ca., 39 degrees S), during 17 months to analyze the seasonal variability in population abundances and zonation of the most common species of the intertidal macroinfauna. The beaches displayed differences in mean grain size, Dean's parameter (a composite index of wave and sediment characteristics) and beach face slope. The peracarids Orchestoidea tuberculata Nicolet (Amphipoda, Talitridae), Excirolana braziliensis Richardson and Excirolana hirsuticauda Menzies (Isopoda, Cirolanidae), and the anomuran crab Emerita analoga (Stimpson) (Hippidae) were the most common organisms at both beaches, being E. analoga and E. hirsuticauda the top contributors to abundance. O. tuberculata tended to occur in higher abundance, either during autumn - early winter or late summer - early autumn; E. braziliensis was more abundant during summer - early autumn, while the abundances of E. hirsuticauda and E. analoga were quite erratic throughout seasons. In general, the temporal patterns of abundance did not show significant correlations with the beach physical factors considered. The species showed a clear pattern of zonation: O. tuberculata occurred in the upper beach levels (around the drift line); E. braziliensis occurrred in the mid - upper levels of the retention zone; E. hirsuticauda occurred throughout all the retention zone and also in the upper and middle levels of the resurgence zone, while E. analoga was mostly found in the swash zone and lower levels of the resurgence zone. Although, seasonal changes in the intertidal distribution was observed, it can be seen that each physical zone of the beaches is biologically distinct through seasons.

Jelgersma, S., M.J.F. Stive, and L. Vandervalk, Holocene Storm-Surge Signatures in the Coastal Dunes of the Western Netherlands, Marine Geology, 125 (1-2), 95-110, 1995.

On five different sites along the central Netherlands' coast one or more sequences of shell deposits in the dunes have been observed. They are believed to be the result of storm surge activity on the foreshore, either through swash or overwash action, and of subsequent preservation due to aeolian coverage of a basically sedimentary coastal system. Through their stratigraphical positions and radiocarbon dating of shell material their approximate age was determined. By interpretation of the role of dynamic wave set-up and run-up the associated storm surge elevations relative to contemporary mean sea level are reconstructed. Although our data may not be statistically accurate, an increasing level of storm surge elevations over the recent Holocene is observed with a particular maximum during the Little Ice Age. It is our suggestion that climatic variations on the one hand and foreshore bathymetry on the other hand may be factors of relevance to explain these observations. If these findings are correct this would imply that for a proper analysis of exceedance frequencies of extreme storm surge events it would be relevant to base such an analysis not only on present climate and foreshore bathymetry.

Jones, A.R., A. Murray, and R.E. Marsh, A method for sampling sandy beach amphipods that tidally migrate, Marine and Freshwater Research, 49 (8), 863-865, 1998.

Some sandy beach species display tidally-related, across-beach migrations. Such behaviour can produce false or misleading results when standard sampling methods are used. To address this problem, a novel method was developed for sampling migratory amphipod populations that maintain position in the swash zone. This method provides sampling repeatability at any stage of the tide by locating the water's edge, defined as the median of the upper limits of II consecutive waves, and thus locating the migrating population. Data to test the hypothesis of choice are then obtained via replicate core samples taken at fixed levels above and below the water's edge.

Jonsson, I.G., O. Skovgaard, and O. Brinkkjaer, Diffraction and Refraction Calculations For Waves Incident On an Island, Journal of Marine Research, 34 (3), 469-496, 1976.


Jonsson, I.G., Friction Factor Under Oscillatory Waves - Discussion, Journal of the Waterways Harbors and Coastal Engineering Division-Asce, 102 (1), 108-109, 1976.


Jonsson, I.G., Power Resource Estimate of Ocean Surface-Waves, Ocean Engineering, 4 (4-5), 211-212, 1977.


Jonsson, I.G., Energy Flux and Wave Action in Gravity-Waves Propagating On a Current, Journal of Hydraulic Research, 16 (3), 223-234, 1978.


Jonsson, I.G., O. Brinkkjaer, and G.P. Thomas, Wave Action and Set-Down For Waves On a Shear Current, Journal of Fluid Mechanics, 87 (AUG), 401-416, 1978.


Jonsson, I.G., Determination of a Bed Friction Factor For Botany Bay, Australia - Discussion, Coastal Engineering, 3 (1), 67-74, 1979.


Jonsson, I.G., Addition, Ocean Engineering, 7 (4), 567-570, 1980.


Jonsson, I.G., Sand Bed Friction Factors For Oscillatory Flows - Discussion, Journal of the Waterway Port Coastal and Ocean Division-Asce, 106 (3), 423-424, 1980.


Jonsson, I.G., New Approach to Oscillatory Rough Turbulent Boundary-Layers, Ocean Engineering, 7 (1), 109-152, 1980.


Jonsson, I.G., and J.D. Wang, Current-Depth Refraction of Water-Waves, Ocean Engineering, 7 (1), 153-171, 1980.


Jonsson, I.G., and H. Kofoedhansen, Pressure and Set Down For Higher-Order Stokes Waves On Current, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 119 (5), 496-504, 1993.

The Bernoulli equation for higher-order Stokes waves on a steady current over a horizontal, impermeable bed was analyzed, and an ambiguity was detected in the determination of the wave- induced pressure at even-order theories. This leads to the introduction of a new (reduced) Bernoulli constant. A simple relation between this quantity and the current-wave set down is presented, and the set down correct to the fourth order in wave steepness is calculated. The finding of the fourth-order current-wave set down is a necessary step to allow calculation of the wave height for fourth-order shoaling in the presence of a current. Finally, the difference between a wave quantity belonging to nth-order theory and being correct to the nth order is discussed, and guidelines are offered for the determination of the former and the corresponding dispersion relation.

Jonsson, I.G., and L. Arneborg, Energy Properties and Shoaling of Higher-Order Stokes Waves On a Current, Ocean Engineering, 22 (8), 819-&, 1995.

The energy density, the energy flux, the set-down, the radiation stress, and some wave energy velocities have been derived correct to fourth order in wave steepness for waves on a vorticity-free current. The energy flux and the set-down have been used for shoaling predictions for finite amplitude waves with and without a net volume flux. The results with a zero volume flux are compared with more accurate shoaling predictions showing rather good accordance, except for large steepnesses. This also applies to the deep water wave energy transport velocity. The results with a net volume flux show that the steepness of the waves reduces the influence of this Aux on the wave evolution. Some problems in connection with the orders in Stokes waves are discussed, among others concerning the dispersion relation and the orders of integral properties. Bed shear and accompanying dissipation is neglected.

Jonsson, I.G., Wave action flux: a physical interpretation, Journal of Fluid Mechanics, 368, 155-164, 1998.

Steady, gravity water waves on a constant-over-depth current, progressing over a slowly varying bed, are studied with the purpose of connecting the wave action flux concept with conventional energy flux considerations. The analysis is two- dimensional and dissipation is neglected. A new relation between integral properties containing the energy flux referred to a 'global' level, the so-called mean energy level, gives the surprising result that this flux is simply the product of absolute angular frequency and wave action flux. An alternative, less physical, proof of this result is also presented. A general equation for the action velocity is set out and for linear waves shown to equal a well-known expression. Also presented are new expressions for relative phase velocity in terms of kinetic energy and mean momentum for the wave, and the kinetic energy in terms of the characteristic velocities for the combined wave and current motion. In the Appendix a simple relation between energy and action fluxes for small-amplitude waves on a linear shear current is found which resembles the irrotational theory, finite-height result. A possible extension of this relation to finite-height waves on a general shear current is discussed.

Jonsson, I.G., and C.M. Steenberg, Characteristic velocities for higher-order Stokes waves in deep water, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 125 (3), 109-117, 1999.

The accuracy of asymptotic expressions for phase, wave energy, and wave action velocities for steady, plane gravity waves progressing in deep water and with no ambient currents is investigated. The calculations are to a large extent based on Fenton's fifth-order Stokes wave theory. Using the dispersion relation correct to sixth order for arbitrary water depth, the phase velocity is calculated to fourth order in wave steepness for infinitely deep water; this is in accordance with a number of previously found results. Potential and kinetic energy is calculated, which leads to the energy density correct to sixth order. Comparison with previous findings showed one discrepancy, which can however be explained. Also, the energy Aux is found correct to sixth order, leading to a fourth-order expression for the wave energy velocity. From sixth-order action and action flux results, the wave action velocity is finally calculated correct to fourth order. Agreement with more accurate numerical results is excellent for all three velocities except near the wave of maximum steepness. Practical asymptotic formulas are introduced, enabling one to calculate the characteristic velocities explicitly from given wave height and period. Two new exact relations between integral properties for deep water with no current are presented.

Kana, T.W., E.J. Hayter, and P.A. Work, Mesoscale sediment transport at southeastern US tidal inlets: Conceptual model applicable to mixed energy settings, Journal of Coastal Research, 15 (2), 303-313, 1999.

Prediction of shoreline change around inlets at meso-time scales (years to decades) is the next logical step following verification of microscale models. If mesoscale simulations are a goal, a basic question is how microscale models (that simulate processes at hours to weeks) can be scaled up in time or whether macroscale geomorphic models (that qualitatively describe changes at decades to centuries) can become more quantitative. The authors propose an approach that begins with consideration of tidal inlet morphology and sediment circulation around ebb-tidal deltas. Inlets are the focus because in some barrier island settings such as the southeast U.S. coast, it appears a majority of coastal erosion problems at meso-time scales can be traced to changes in adjacent inlets. Inlet morphology and geomorphic models, typical of mixed-energy coastal plain shorelines, are reviewed to illustrate certain common sediment transport patterns. A simplified conceptual model of inlets at meso-time scale is proposed from which the problem of sediment transport may be spatially partitioned. Four primary inlet domains are considered: (A) main ebb channel where tidally generated ebb currents control sediment discharge, (B) ebb-tidal delta with a broad swash platform that is ultimately in balance between ebb- directed flows and wave- and tide-generated shoreward transport, (C) shoal-bypassing zones at the margins of the ebb- tidal delta where sediment shifts unidirectionally from the delta to the shoreline under wave-generated transport, and (D) recurved spits adjacent to the inlet which receive shoal-bypass sediments. Excess sand accumulating in Domain D becomes subject to longshore advection toward and away from the inlet. A portion nourishes the adjacent beach and the remainder recycles back to the inlet channel (Domain A), completing the inlet transport loop.

Karunarathna, H., and K. Tanimoto, Long-period water surface fluctuations on a horizontal coastal shelf with a steep seaward face, Coastal Engineering, 29 (1-2), 123-147, 1996.

Steep slopes significantly influence the propagation of both short period waves and accompanying long-period waves with the same time scale as the wave groups. Therefore, conventional wave models are not directly appropriate for the computation of the wave field on such a slope. A numerical model is proposed for the simulation of long-period water surface fluctuations forced by short-period wave groups. This model is based on the generalized conservation equations of mass and momentum. The conventional closure relationship used for radiation stresses in most previous long-period wave models is upgraded for steep slopes and an explicit relationship is found for the dynamic component of the mean bottom pressure. The model is verified through some wave flume data collected on a steep slope. The model is then used to investigate long-period water surface fluctuations on horizontal shelves with steep seaward faces. It is found through numerical investigations that the long-period water surface fluctuations on a steeply faced coastal shelf greatly depend on the transmission of short-period waves. For short-period waves propagating without breaking, steeply faced shelves provide large long-period waves while opposite is true for breaking short-period waves.

Kazanci, N., O. Ileri, B. Varol, and M. Ergin, On the significance of small-scale and short-lived air escape structures for the destruction of primary sedimentary laminations in the Colakh Beach deposits, Gulf of Antalya, Turkey (Eastern Mediterranean), Estuarine Coastal and Shelf Science, 47 (2), 181-190, 1998.

Colakh beach is a 4 km long coastal depositional system on the Mediterranean coast of southern Turkey. It has been accumulating at the foot of Taurus tectonic belt since the late Pleistocene. The beach deposits are composed of fine-grained sands with no significant longshore changes in granulometry and mineralogy. In addition, the sequence of beach deposits is characterized by a homogenous internal appearance due to the lack of preserved primary sedimentary structures. On the foreshore, air-escape structures comprising small tubes, 5-30 mm in length and 0.5-3 mm in width are extensively formed along the upper swash zone during the backwash phase of wave action. When the next wave swashes across the beach, the former structures are destroyed, at the same time producing conditions for the creation of new ones. The escape structures destroy the original sedimentary lamination. It is thus proposed that the homogenous internal appearance of the older beach deposits has been produced by the same mechanism. (C) 1998 Academic Press.

Kim, C.S., and D.A. Huntley, On Time Delays in the Nearshore Zone Between Onshore and Longshore Currents At Incident Wave Frequencies, Journal of Geophysical Research-Oceans, 91 (C3), 3967-3978, 1986.


Kobayashi, N., and A.M. Reece, Irregular Wave Overtopping On Gravel Islands, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 109 (4), 429-444, 1983.


Kobayashi, N., and B.K. Jacobs, Riprap Stability Under Wave Action, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 111 (3), 552-566, 1985.


Kobayashi, N., Irregular Wave Overtopping On Gravel Islands - Closure, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 111 (1), 147-150, 1985.


Kobayashi, N., Riprap Stability Under Wave Action - Closure, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 112 (6), 673-681, 1986.


Kobayashi, N., and D. Aktan, Thermo-Erosion of Frozen Sediment Under Wave Action, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 112 (1), 140-158, 1986.


Kobayashi, N., and S. Frankenstein, Wave Drift Force On Ice-Floe, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 113 (5), 476-492, 1987.


Kobayashi, N., A.K. Otta, and I. Roy, Wave Reflection and Run-Up On Rough Slopes, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 113 (3), 282-298, 1987.


Kobayashi, N., Review of Wave Transformation and Cross-Shore Sediment Transport Processes in Surf Zones, Journal of Coastal Research, 4 (3), 435-445, 1988.


Kobayashi, N., and A. Wurjanto, Wave Transmission Over Submerged Breakwaters, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 115 (5), 662-680, 1989.


Kobayashi, N., and A. Wurjanto, Wave Overtopping On Coastal Structures, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 115 (2), 235-251, 1989.


Kobayashi, N., Wave Reflection and Run-Up On Rough Slopes - Closure, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 115 (1), 143-148, 1989.


Kobayashi, N., G.S. Desilva, and K.D. Watson, Wave Transformation and Swash Oscillation On Gentle and Steep Slopes, Journal of Geophysical Research-Oceans, 94 (C1), 951-966, 1989.


Kobayashi, N., D.T. Cox, and A. Wurjanto, Irregular Wave Reflection and Run-Up On Rough Impermeable Slopes, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 116 (6), 708-726, 1990.


Kobayashi, N., D.T. Cox, and A. Wurjanto, Permeability Effects On Irregular Wave Runup and Reflection, Journal of Coastal Research, 7 (1), 127-136, 1991.

Six small-scale test runs were conducted to examine the detailed spectral and time series characteristics of irregular wave reflection and runup on 1:3 rough impermeable and permeable slopes. The permeability effects reduced the average reflection coefficient and significant runup as was observed by a number of researchers. The permeability effects on irregular wave reflection were found to reduce the reflection coefficient fairly uniformly over the wind wave frequency range. The permeability effects on irregular wave runup were found to reduce the low frequency wave components significantly. The measured runup distributions in the range of the exceedance probability greater than approximately 0.02 were represented by the Rayleigh distribution fairly well.

Kobayashi, N., and A. Wurjanto, Irregular Wave Setup and Run-Up On Beaches, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 118 (4), 368-386, 1992.

The one-dimensional equations of mass, momentum, and energy are derived from the two-dimensional continuity and Reynolds equations in order to elucidate the approximations involved in these one-dimensional equations, which have been used previously to predict normally incident wave motions on coastal structures and beaches. The numerical model based on these equations is compared qualitatively with the wave setup and swash statistics on a moderately steep beach with a nearshore bar. The numerical model is shown to predict the irregular wave transformation and swash oscillation on the barred beach, at least qualitatively. The computed setup and swash heights are found to follow the lower bound of scattered data points partly because of the neglect of the longshore variability on the natural beach and low-frequency components in the specified incident wave train. A more quantitative comparison is also made with the spectrum of the shoreline oscillation measured on a 1:20 plane beach, for which the corresponding wave spectrum was given. Thc numerical model is shown to predict the dominant low-frequency components of the measured spectrum fairly well.

Kobayashi, N., A.W. Raichle, and T. Asano, Wave Attenuation By Vegetation, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 119 (1), 30-48, 1993.

The vertically two-dimensional problem of small-amplitude waves propagating over submerged vegetation is formulated using the continuity and linearized momentum equations for the regions above and within the vegetation. The effects of the vegetation on the flow field are assumed to be expressible in terms of the drag force acting on the vegetation. An analytical solution is obtained for the monochromatic wave whose height decays exponentially. The expressions for the wave number and the exponential decay coefficient derived for arbitrary damping arc shown to reduce to those based on linear wave theory and the conservation equation of energy if the damping is small. The analytical solution is compared with 60 test runs conducted using deeply submerged artificial kelp. The calibrated drag coefficients for these runs are found to vary in a wide range and appear to be affected by the kelp motion and viscous effects that are neglected in the analysis. The analytical solution is also shown to be applicable to subaerial vegetation, which is predicted to be much more effective in dissipating wave energy.

Kobayashi, N., and E.A. Karjadi, Surf-Similarity Parameter For Breaking Solitary-Wave Runup, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 120 (6), 645-650, 1994.


Kobayashi, N., and A.W. Raichle, Irregular Wave Overtopping of Revetments in Surf Zones, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 120 (1), 56-73, 1994.

Twelve test runs were conducted to examine the overtopping processes of normally incident irregular waves over a revetment of a 1:2 rough impermeable slope fronted by a gentle, smooth slope and situated well inside the surf zone. The measured overtopping probability and average overtopping rate are affected noticeably by the spectral shape and wave grouping of the incident irregular waves measured immediately outside the surf zone. The empirical procedure for estimating these overtopping quantities is found to yield only order-of- magnitude estimates for this experiment. The measurements made for the 12 runs are used to calibrate and evaluate the existing one-dimensional, time-dependent numerical model, which is modified slightly to allow the spatial variation of the bottom friction factor. The calibrated numerical model is shown to be fairly capable of predicting the average overtopping rate and the depth of overtopping flow on the crest of the revetment. The measured and predicted time series and spectra of the flow depth including entrained air show the grouped nature of irregular wave overtopping events.

Kobayashi, N., Y. Tega, and M.W. Hancock, Wave reflection and overwash of dunes, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 122 (3), 150-153, 1996.

Seven tests consisting of 72 runs were conduced to measure wave reflection, overtopping, and overwash of dunes. The measured reflection coefficients and overtopping rates are compared with the empirical formulas developed for coastal structures. The equivalent uniform slope for reflection is assumed to be the beach slope at the still water shoreline. The equivalent uniform slope for overtopping is assumed to be the overall slope between the dune crest and the point where the water depth equals the significant wave height. The toe depth of the coastal structure is assumed to correspond to the water depth immediately seaward of the breaker zone on the beach. The formulas with these adjustments are then shown to predict the order of magnitude of the measured reflection coefficients and overtopping rates. Furthermore, the average volumetric sand concentration in the overwash flow was measured to be approximately 0.04 for these small-scale tests.

Kobayashi, N., and E.A. Karjadi, Obliquely incident irregular waves in surf and swash zones, Journal of Geophysical Research-Oceans, 101 (C3), 6527-6542, 1996.

A time-dependent numerical model is developed for predicting the free surface elevation and depth-averaged cross-shore and alongshore velocities in the swash and surf zones under obliquely incident irregular waves. The assumption of small incident angles is made to simplify the finite-amplitude, shallow-water equations and allow the computation of the cross- shore fluid motion using the existing one-dimensional model for normally incident waves. The developed numerical model is compared with available field data. The time-dependent model is shown to be capable of predicting the cross-shore variations of the root-mean-square wave height and longshore current in the surf zone. The numerical model predicts large cross-shore and alongshore velocities near the shoreline. The causes of these large velocities are examined but cannot be ascertained for lack of velocity data near the shoreline.

Kobayashi, N., E.A. Karjadi, and B.D. Johnson, Dispersion effects on longshore currents in surf zones, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 123 (5), 240-248, 1997.

A time-dependent model for obliquely incident shallow-water waves with small incident angles is developed to elucidate the dispersion effects due to the vertical variations of instantaneous horizontal fluid velocities on the cross-shore variations of the wave height, setup, and longshore current in surf zones. The three equations for the cross-shore continuity, momentum, and momentum flux correction are solved numerically to predict the water depth and the cross-shore depth-averaged and near-bottom velocities. The two equations for the alongshore momentum and momentum flux correction are derived and solved to predict the alongshore depth-averaged and near- bottom velocities. The developed model is compared with laboratory and field data for planar beaches. The dispersion effects on the wave height and setup are shown to be minor. The dispersion effects on the longshore current are significant for regular waves but secondary for irregular waves. The model is also shown to predict the vertical shape of the longshore current in the surf zone but not outside the surf zone.

Kobayashi, N., M.N. Herrman, B.D. Johnson, and M.D. Orzech, Probability distribution of surface elevation in surf and swash zones, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 124 (3), 99-107, 1998.

Three irregular wave tests were conducted on a 1:16 smooth impermeable slope to investigate the detailed cross-shore variations of the probability distributions and statistics of the free surface elevations and middepth horizontal velocities in the shoaling, surf, and swash zones. The exponential gamma distribution with the measured mean, standard deviation, and skewness is shown to be capable of describing the measured probability distributions in a unified manner, although the agreement becomes worse in the lower swash zone. The probability distribution of the free surface elevation whose lower limit is imposed by the beach face in the swash zone becomes exponential with the skewness s = 2 and the standard deviation sigma = (h) over bar with (h) over bar = mean water depth. These upper limits of s and sigma/h in the lower swash zone are in qualitative agreement with the data in the region of (h) over bar greater than or similar to 0.4 cm in these small-scale tests. The cross-shore variations of the mean (undertow) and standard deviation of the middepth horizontal velocity measured in the shoaling and surf zones can be predicted fairly accurately using the simple relationships derived using linear long-wave theory together with the measured values of (h) over bar and sigma. The adopted distribution and these simple relationships will need to be verified using extensive data on sand beaches of various profiles.

Lee, C.T., Textural variations over a foreshore-backshore environment, Hawaii, Physical Geography, 18 (3), 263-290, 1997.

Detailed textural analyses in a carbonate foreshore-backshore coastal environment in Hawaii indicated distinct differences in mean, sorting, skewness, and percent of fines between zones and within zones. A well-developed berm crest partitioned the 1,000 m(2) grid into foreshore (n = 79) and backshore (n = 46) zones. As a group, foreshore sediments were finer, better sorted, and more negatively skewed than backshore sediments. This pattern was thought to reflect the decoupling of the foreshore source population by swash-backwash and eolian processes. Spatial variations in texture within the foreshore were also observed, and this led to the subdivision of the foreshore into three zones based on observed textural variations-lower foreshore, mid-foreshore, and upper foreshore. The lower foreshore was found to be statistically coarser, more poorly sorted, and more positively skewed than the other foreshore zones. The mid- foreshore zone was the finest, and the upper foreshore was intermediate in grain size. This patterning was thought to reflect the greatest energy dissipation in the lower foreshore, subsequent competency decrease of swash runup, and deposition of coarsest particles remaining in transport in the upper foreshore, accompanied by infiltration losses in the backwash and deposition of the finest materials in the mid-foreshore zone. Traditional bivariate plots of textural parameters for the foreshore and backshore samples indicated that this approach alone would not be useful in distinguishing subenvironments in paleosequence studies. A mean value approach (MVA) was developed and used in combination with published bivariate plots to identify depositional environments using moment statistics. Encouraging results were obtained from Waimanalo Beach sediments and from data published in the literature. The bivariate (textural) suite statistics approach (Tanner, 1991b) was used to test for correct environmental recognition using the 125 beach samples. Results at first appeared promising, but assessment of literature data illustrated that the original suite diagrams could usefully be expanded. These results support previous statements that textural studies should not be used as the only tool in paleoenvironmental reconstruction.

Lentz, S., and B. Raubenheimer, Field observations of wave setup, Journal of Geophysical Research-Oceans, 104 (C11), 25867-25875, 1999.

Wave setup is assumed to be a balance between the cross-shore convergence of the onshore flux of momentum (wave radiation stress S-xx) in the surfzone and a cross-shore pressure gradient. Oceanic observations between the 2- and 8-m isobaths near Duck, North Carolina, provide a test of the wave setup balance without assuming that wave height in the surfzone is proportional to water depth. Analysis of data from a cross- shore array of 11 pressure gauges and 10 sonar altimeters deployed during the fall of 1994 indicates the wave setup balance holds to at least the accuracy of the pressure measurements (a few centimeters). The correlation between the two terms in the setup balance is 0.93, and the linear regression slope is 1.05 +/- 0.19. Accurate estimates of the cross-shore pressure gradient require density measurements to adjust pressure measurements taken at different depths to the same level. The assumption that pressure and bathymetry are linear between the 2- and 8-m isobaths (or the more common assumption that the height of normally incident, shallow water waves is proportional to the water depth) introduces errors of up to 6 cm for the conditions considered here. Given this assumption, 3.5 years of data from pressure gauges in 2 and 8 m of water indicate that the wave setup balance is valid for a wide range of conditions (correlation 0.71 and regression slope 0.98 +/- 0.08).

Leontyev, I.O., Numerical modelling of beach erosion during storm event, Coastal Engineering, 29 (1-2), 187-200, 1996.

A model is proposed that describes short-term changes in beach profile due to attack by storm waves. A key assumption is that the total sediment transport rate q in the nearshore area may be decomposed into two distinct components. The first is rate q(w) induced by wave/current mechanisms and the second is rate q(R) generated by run-up flow. In the swash zone q(W) = 0 and q = q(R); in the wave shoaling zone q(R) = 0 and q = q(W) and in the surf zone q = q(W) + q(R). the q(W) term can be determined from the existing models of nearshore dynamics and in present work the author's 1995 model is used. The swash zone contribution q(R) is parameterized in terms of run-up height and equilibrium beach slope gradient. Temporal changes in beach profile are computed from the mass balance equation, A numerical procedure includes the module simulating the avalanche conditions. The model is tested against data from prototype-scale wave tank experiments and field observations.

Leontyev, I.O., Beach profile development during a storm, Okeanologiya, 37 (1), 136-144, 1997.

A model is proposed describing short-term changes in a beach profile due to influence of stormy waves, The key assumption is the total sediment transport rate q in the nearshore area may be decomposed in two distinct components. The first is the rate q(w) induced by wave/current mechanisms and the second is the rate q(R) generated by a run-up flow. In the swash zone q(W)= 0 and q = q(R), in the wave shoaling zone q(R) = 0 and q = q(W) and in the surf zone q= q(W) + q(R). The q(W) term can be determined from the existing models of nearshore dynamics and it is used in the present work, The swash zone contribution q(R) is parameterized in terms of run-up height and equilibrium beach slope gradient, Temporal changes in beach profile are computed from the mass balance equation. A numerical procedure includes the module simulating the avalanche condition. The model is tested against data from prototype-scale wave tank experiments [19].

Levoy, F., E. Anthony, J.P. Barusseau, H. Howa, and B. Tessier, Morphodynamics of a macrotidal ridge and runnel beach, Comptes Rendus De L Academie Des Sciences Serie Ii Fascicule a- Sciences De La Terre Et Des Planetes, 327 (12), 811-818, 1998.

The topography, currents, waves, and sediment dynamics of a macrotidal ridge and runnel beach were monitored from April 24 to May 4, 1997 in order to characterise the morphodynamics of this beach type under fair-weather and storm conditions. Sand tracer experiments show moderate longshore and cross-shore transport components while profile surveying highlights a remarkably stable system. These trends are not in agreement with the current pattern, which is dominated by an essentially tidally driven longshore component. The stability of the ridges reflects the high rates of migration of the breaker/swash zone in response to the important vertical tidal excursion across a wide, low-gradient beach. ((C) Academie des sciences / Elsevier, Paris.).

Li, L., D.A. Barry, J.Y. Parlange, and C.B. Pattiaratchi, Beach water table fluctuations due to wave run-up: Capillarity effects, Water Resources Research, 33 (5), 935-945, 1997.

High-frequency beach water table fluctuations due to wave run- up and rundown have been observed in the field [Waddell, 1976]. Such fluctuations affect the infiltration/exfiltration process across the beach face and the interstitial oxygenation process in the beach ecosystem. Accurate representation of high- frequency water table fluctuations is of importance in the modeling of (1) the interaction between seawater and groundwater, more important, the effects on swash sediment transport and (2) the biological activities in the beach ecosystem. Capillarity effects provide a mechanism for high- frequency water table fluctuations. Previous modeling approaches adopted the assumption of saturated flow only and failed to predict the propagation of high-frequency fluctuations in the aquifer. In this paper we develop a modified kinematic boundary condition (kbc) for the water table which incorporates capillarity effects. The application of this kbc in a boundary element model enables the simulation of high- frequency water table fluctuations due to wave run-up. Numerical tests were carried out for a rectangular domain with small-amplitude oscillations; the behavior of water table responses was found to be similar to that predicted by an analytical solution based on the one-dimensional Boussinesq equation. The model was also applied to simulate the water table response to wave run-up on a doping beach. The results showed similar features of water table fluctuations observed in the field. In particular, these fluctuations are standing wave- like with the amplitude becoming increasingly damped inland. We conclude that the modified kbc presented here is a reasonable approximation of capillarity effects on beach water table fluctuations. However, further model validation is necessary before the model can confidently be used to simulate high- frequency water table fluctuations due to wave run-up.

Li, Z., and B. Johns, A three-dimensional numerical model of surface waves in the surf zone and longshore current generation over a plane beach, Estuarine Coastal and Shelf Science, 47 (4), 395-413, 1998.

A three-dimensional numerical model is developed for the propagation of shallow-water short-period surface waves in the surf zone and longshore current generation over a plane beach topography. This model, which is based on Reynolds-averaged non-linear shallow-water (NSW) equations and, hence, includes implicitly the classical radiation stress concept, resolves time- and space-dependence of the sea surface elevation and the velocity fields during one wave cycle (short-wave-resolving). The generation of turbulence by wave breaking and vertical fluid shear above the beach is parameterized by the application of a generalized turbulence energy closure scheme. The instantaneous position of the moving shoreline is determined from the model equations during the simulated propagation process. In the case of a single incoming wave train, the wave amplitude, wave period and angle of incidence are prescribed at an offshore open boundary by application of a forced radiation condition. For uniform alongshore topographic conditions, when cyclic boundary conditions are appropriate at alongshore open boundaries whose positions are determined by the alongshore component of wavelength in an incoming single wave train, the model is used to determine the (mean) longshore current during one wave cycle. It is shown that the maximum longshore depth- averaged current occurs at an approximate offshore position where the generation of turbulence energy through wave breaking is a maximum. It is further shown that the cross-shore gradient of the longshore momentum flux is of predominant importance in generating longshore currents. Experiments are described that determine the dependence of the computed longshore current on the bottom roughness and the length scale prescription in that part of the turbulence closure scheme pertaining to the parameterization of the wave breaking process. The implications of the model results are discussed in the context of the longshore bedload transport of sedimentary material. Finally, a comparison is made between the model predictions and observational data on longshore currents and wave heights. (C) 1998 Academic Press.

Li, L., and D.A. Barry, Wave-induced beach groundwater flow, Advances in Water Resources, 23 (4), 325-337, 2000.

Wave-induced beach groundwater flow has been linked to sediment transport in the near-shore zone and chemical transfer from the aquifer to the ocean. The flow dynamics, however, are not well- understood. This paper presents a numerical study of the instantaneous (i.e., phase-resolved) wave motion and resulting groundwater responses in the beach zone. Simulations conducted for a representative beach reveal various important features of the flow. In particular, periodic local groundwater circulation occurs below progressive bores while the averaged flow behaviour is characterised by continuous circulation (due to wave set-up) extending from the upper part of the beach to the lower part. These results are analysed and compared with previous analytical solutions derived for simplified situations. The findings will assist future studies to quantify the effects of beach groundwater flow on other coastal processes. (C) 1999 Elsevier Science Ltd. All rights reserved.

Lin, P.Z., and P.L.F. Liu, A numerical study of breaking waves in the surf zone, Journal of Fluid Mechanics, 359, 239-264, 1998.

This paper describes the development of a numerical model for studying the evolution of a wave train, shoaling and breaking in the surf zone. The model solves the Reynolds equations for the mean (ensemble average) flow field and the k-epsilon equations for the turbulent kinetic energy, k, and the turbulence dissipation rate, epsilon. A nonlinear Reynolds stress model (Shih, Zhu & Lumley 1996) is employed to relate the Reynolds stresses and the strain rates of the mean flow. To track free-surface movements, the volume of fluid (VOF) method is employed. To ensure the accuracy of each component of the numerical model, several steps have been taken to verify numerical solutions with either analytical solutions or experimental data. For non-breaking waves, very accurate results are obtained for a solitary wave propagating over a long distance in a constant depth. Good agreement between numerical results and experimental data has also been observed for shoaling and breaking cnoidal waves on a sloping beach in terms of free-surface profiles, mean velocities, and turbulent kinetic energy. Based on the numerical results, turbulence transport mechanisms under breaking waves are discussed.

Lin, P.Z., and P.L.F. Liu, Turbulence transport, vorticity dynamics, and solute mixing under plunging breaking waves in surf zone, Journal of Geophysical Research-Oceans, 103 (C8), 15677-15694, 1998.

Plunging breaking waves generate turbulence and vorticity, which are of great importance for the solute and sediment transport in surf zone. In this paper the complex breaking processes are simulated by using an accurate numerical model that solves the Reynolds equations for the mean flow and modified k-epsilon equations for the turbulence field. A solute transport model is employed to investigate the solute mixing under plunging waves. After validation of the numerical model by comparing numerical results with available experimental data, the numerical model is further utilized to study the detailed mechanisms of turbulence transport and vorticity dynamics. The differences between spilling and plunging breaking waves are discussed. The impact of the wave breaking on solute mixing in the surf zone is also examined.

Lin, P.Z., K.A. Chang, and P.L.F. Liu, Runup and rundown of solitary waves on sloping beaches, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 125 (5), 247-255, 1999.

This paper presents a combined experimental and numerical effort to study solitary wave runup and rundown on beaches. Both nonbreaking and breaking solitary waves are investigated. A two-dimensional numerical model that solves both mean flow and turbulence is employed in this study. For the nonbreaking solitary wave on a steep slope, numerical results of the present model are verified by experimental data and numerical results obtained from the boundary integral equation method model, in terms of both velocity distribution and free surface profiles. The characteristics of flow patterns during runup and rundown phases are discussed. The vertical variations of the horizontal velocity component are large at some instances, implying that the shallow water approximation may be inaccurate even for the nonbreaking wave runup and rundown. For the breaking solitary wave on a mild slope, numerical results of the present model are compared with experimental data for foe surface displacements. The present model is found to be more accurate than the depth-averaged equations models. Using this numerical model, the mean velocity field and turbulence distribution under the breaking wave are discussed.

Lippmann, T.C., R.A. Holman, and A.J. Bowen, Generation of edge waves in shallow water, Journal of Geophysical Research-Oceans, 102 (C4), 8663-8679, 1997.

Theoretical growth rates for resonantly driven edge waves in the nearshore are estimated from the forced, shallow water equations of motion for the case of a plane sloping bed. The forcing mechanism arises from spatial and temporal variations in radiation stress gradients induced by a modulating incident wave field. Only the case of exact resonance is considered, where the difference frequencies and wavenumbers satisfy the edge wave dispersion relation (the specific carrier frequencies are not important, only the forced difference values). The forcing is examined in the region seaward of the breakpoint and also within the fluctuating region of surf zone width. In each region, the forcing is dominated by the cross-shore gradient of onshore directed momentum flux, except for large angles of incidence and the lowest edge wave modes. Outside the surf zone, the spatial and temporal variation of the forcing is determined by considering the interaction of two progressive shallow water waves approaching the beach obliquely. In the surf zone, incident wave amplitudes are assumed to be proportional to the water depth. Thus inside the breakpoint, radiation stress gradients are constant and no forcing occurs. However, at the breakpoint, gradients arising from breaking and nonbreaking waves are turned on and off (like a wave maker) with timescales and length scales determined by the modulation of the breaker position. The forcing in this region is stronger, with inviscid growth rates resulting in edge waves growing to the size of the incident waves of the order of about 10 edge wave periods, a factor of 2-10 times larger than in the offshore region. Using a simple parameterization for frictional damping, edge wave equilibrium amplitudes are found to depend linearly on the ratio tan beta/C-d, where beta is the beach slope and C-d is a bottom drag coefficient. For tan beta/C-d about 3-10, equilibrium amplitudes can be as much as 75% of the incident waves over most of the infragravity portion of the spectrum. When the forcing is turned off, these dissipation rates result in a half-life decay timescale of the order of 10- 30 edge wave periods.

Lippmann, T.C., T.H.C. Herbers, and E.B. Thornton, Gravity and shear wave contributions to nearshore infragravity motions, Journal of Physical Oceanography, 29 (2), 231-239, 1999.

Data from a cross-shore array of nine collocated pressure sensors and bidirectional current meters, extending from the shoreline to approximately 4.5-m depth, are used to estimate the relative contributions of gravity waves (e.g., edge and leaky waves) and instabilities of the alongshore current (shear waves) to motions in the infragravity (frequencies nominally 0.004-0.05 Hz) band. The ratio between frequency-integrated velocity and pressure variances is shown to be approximately equal to g/h for a broad spectrum of gravity waves independent of the mode mix of edge and leaky waves. Since shear waves have velocity to pressure variance ratios >> g/h, this ratio can be used to estimate the relative contributions of gravity and shear waves to the infragravity band. Outside the surf zone where the shear in the along shore current is relatively weak, the observed velocity to pressure variance ratios are approximately equal to g/h, consistent with a gravity-dominated wave field. Inside the surf zone where alongshore currents are strongly sheared, these ratios are up to a factor of 4 larger, indicating that shear waves contribute as much as 75% of the velocity variance in the infragravity band. Observed shear- wave-dominated infragravity band motions are confined to a narrow region of strong shear on the seaward side of the alongshore current maximum, and their cross-shore structure appears to be insensitive to changes in the beach profile, qualitatively consistent with theoretical predictions by linear stability analysis.

Litvin, E.N., K.V. Pokazeev, and V.N. Tuporshin, Infragravity Waves in Mouth of the River Kamshatka, Okeanologiya, 32 (2), 211-218, 1992.

The oscillations of sea level were measured in 3 points with probes of pressure in the mouth of the river Kamshatka in september of 1988 and spectral analysis of these oscillations was performed. In wave spectrum there are wind waves, swell and infragravity waves with frequency 0,002-0,05 Hz. Infragravity waves have high correlation with wave groups. There is connection between energy of infragravity waves with energy of wind waves and swell.

Liu, P.L.F., C.E. Synolakis, and H.H. Yeh, Report On the International Workshop On Long-Wave Run-Up, Journal of Fluid Mechanics, 229, 675-&, 1991.

A workshop reviewing the current research on long-wave run-up was held in the Marine Science Center of the University of Southern California at Catalina Island, California, in August 1990. The workshop covered theoretical, experimental, and field studies of run-up phenomena. The primary application of the research results discussed was in tsunami run-up and flooding and in tsunami run-up hazard mitigation. Certain other applications of long-wave run-up related to wind waves were also discussed. This report summarizes the twenty-six papers presented and it provides one particular view of the current understanding of this run-up process.

Liu, P.L.F., Y.S. Cho, M.J. Briggs, U.K. Lu, and C.E. Synolakis, Runup of Solitary Waves On a Circular Island, Journal of Fluid Mechanics, 302, 259-285, 1995.

This is a study of the interactions of solitary waves climbing up a circular island. A series of large-scale laboratory experiments with waves of different incident height-to-depth ratios and different crest lengths is described. Detailed two- dimensional run-up height measurements and time histories of surface elevations around the island are presented. A numerical model based on the two-dimensional shallow-water wave equations including runup calculations was developed. Numerical model predictions agreed very well with the laboratory data and the model was used to study wave trapping and the effect of slope. Under certain conditions, enhanced runup and wave trapping on the lee side of the island were observed, suggesting a possible explanation for the devastation reported by field surveys in Babi Island off Flores, Indonesia, and in Okushiri Island, Japan.

Losada, I.J., R.A. Dalrymple, and M.A. Losada, Wave-induced mean flows in vertical rubble mound structures, Coastal Engineering, 35 (4), 251-281, 1998.

Waves impinging on rubble mound breakwaters and seawalls induce a mean flow within the breakwater, analogous to the so-called undertow within the surf zone. Here, using a plane wave approximation (kh < 1.5), a second-order problem is solved for an idealized breakwater with a rectangular cross-section to show the origin and the nature of the mean flow within the porous structure. The mean flow is expressed in terms of a mean stream function analytically derived, obtained based on the mass flux balance between the incident, reflected and transmitted waves. Furthermore, the evolution of other second- order magnitudes such as mean water level and mass flux is analyzed under different incident wave conditions, structure geometry and porous material characteristics. Results show that the evolution of the different mean quantities is controlled mainly by reflection and consequently depends highly on structure geometry and porous material characteristics. Furthermore, it is shown that the return flow is stronger with increasing mass flux decay. Some qualitative experiments to show the described mechanism are also presented. (C) 1998 Elsevier Science B.V. All rights reserved.

Luccio, P.A., S.I. Voropayev, H.J.S. Fernando, D.L. Boyer, and W.N. Houston, The motion of cobbles in the swash zone on an impermeable slope, Coastal Engineering, 33 (1), 41-60, 1998.

The purpose of this communication is to present the results of a series of laboratory experiments aimed at better understanding the dynamics of the motion of large bottom particles (cobbles) in a swash zone. In this region, a thin sheet of water that results from the collapse of a turbulent bore, runs up the beach and can induce the transport of relatively large solid objects in the on-shore direction. The aims of the study were to: (i) mimic this process in laboratory experiments and identify the associated physical processes involved and (ii) to develop a suitable theoretical model to describe the motion of cobbles. The experiments employed a solid impermeable bottom and were conducted in a long tank of rectangular cross-section. An impulsive hydraulic bore, produced by a dam-break mechanism at one end of the tank, was used to simulate the water motion in the swash zone. Solid objects of simple discoid shape were used to model the cobbles. The results of the laboratory observations were compared with model predictions. In the range of external parameters used for the experiments (size and density of cobbles, propagation velocity and height of the water front, slope and friction at the bottom), a reasonable agreement between the measured and calculated values of the cobble displacement as a function of time was obtained. (C) 1998 Elsevier Science B.V.

Madsen, P.A., O.R. Sorensen, and H.A. Schaffer, Surf zone dynamics simulated by a Boussinesq type model. Part I. Model description and cross-shore motion of regular waves, Coastal Engineering, 32 (4), 255-287, 1997.

This is the first of three papers on the modelling of various types of surf zone phenomena. In this first paper, part I, the model is presented and its basic features are studied for the case of regular waves. The model is based an two-dimensional equations of the Boussinesq type and it features improved linear dispersion characteristics, possibility of wave breaking, and a moving boundary at the shoreline. The moving shoreline is treated numerically by replacing the solid beach by a permeable beach characterized by an extremely small porosity. Run-up of nonbreaking waves is verified against the analytical solution for nonlinear shallow water waves. The inclusion of wave breaking is based on the surface roller concept for spilling breakers using a geometrical determination of the instantaneous roller thickness at each point and modelling the effect of wave breaking by an additional convective momentum term. This is a function of the local wave celerity, which is determined interactively. The model is applied to cross-shore motions of regular waves including various types of breaking on plane sloping beaches and over submerged bars. Model results comprise time series of surface elevations and the spatial variation of phase-averaged quantities such as the wave height, the crest and trough elevations, the mean water level, and the depth-averaged undertow. Comparisons with physical experiments are presented. The phase-averaged balance of the individual terms in the momentum and energy equation is determined by time-integration and quantities such as the cross-sectional roller area, the radiation stress, the energy flux and the energy dissipation are studied and discussed with reference to conventional phase- averaged wave models. The companion papers present cross-shore motions of breaking irregular waves, swash oscillations and surf beats (part II) and nearshore circulations induced by breaking of unidirectional and multidirectional waves (part III). (C) 1997 Elsevier Science B.V.

Madsen, P.A., O.R. Sorensen, and H.A. Schaffer, Surf zone dynamics simulated by a Boussinesq type model. Part II: Surf beat and swash oscillations for wave groups and irregular waves, Coastal Engineering, 32 (4), 289-319, 1997.

This is the second of three papers on the modelling of various types of surf zone phenomena. In the first paper the general model was described and it was applied to study cross-shore motion of regular waves in the surf zone. In this paper, part II, we consider the cross-shore motion of wave groups and irregular waves with emphasis on shoaling, breaking and runup as well as the generation of surf beats. These phenomena are investigated numerically by using a time-domain Boussinesq type model, which resolves the primary wave motion as well as the long waves. As compared with the classical Boussinesq equations, the equations adopted here allow for improved linear dispersion characteristics and wave breaking is modelled by using a roller concept for spilling breakers. The swash zone is included by incorporating a moving shoreline boundary condition and radiation of short and long period waves from the offshore boundary is allowed by the use of absorbing sponge layers. Mutual interaction between short waves and long waves is inherent in the model. This allows, for example, for a general exchange of energy between triads rather than a simple one-way forcing of bound waves and for a substantial modification of bore celerities in the swash zone due to the presence of long waves. The model study is based mainly on incident bichromatic wave groups considering a range of mean frequencies, group frequencies, modulation rates, sea bed slopes and surf similarity parameters. Additionally, two cases of incident irregular waves are studied. The model results presented include transformation of surface elevations during shoaling, breaking and runup and the resulting shoreline oscillations. The low frequency motion induced by the primary-wave groups is determined at the shoreline and outside the surf zone by low- pass filtering and subsequent division into incident bound and free components and reflected free components. The model results are compared with laboratory experiments from the literature and the agreement is generally found to be very good. Finally the paper includes special details from the breaker model: time and space trajectories of surface rollers revealing the breakpoint oscillation and thr speed of bores; envelopes of low-pass filtered radiation stress and surface elevation: sensitivity of surf bent to group frequency, modulation rate and bottom slope is investigated. Part III of this work (Sorensen et al., 1998) presents nearshore circulations induced by the breaking of unidirectional and multi-directional waves. (C) 1997 Elsevier Science B.V.

Makaske, B., and P. Augustinus, Morphologic changes of a micro-tidal, low wave energy beach face during a spring-neap tide cycle, Rhone-Delta, France, Journal of Coastal Research, 14 (2), 632-645, 1998.

Detailed profiles of the beach face at the micro-tidal, low wave energy shoreline of the Rhone-Delta were measured up to three times daily during one spring-neap tide cycle. Samples of sedimentary structures and quantitative data of tides, wind, waves, swash and backwash, beach groundwater levels and sediment transport were collected simultaneously. A qualitative model for morphologic changes of the beach face in the Rhone- Delta is based on these data. As the study period did not include storms, the results are only applicable to low wave energy conditions. The morphologic changes of the beach face can be schematized as an alternation of three profile types: (1) straight, (2) concave and (3) convex-concave. The straight profile develops under lower energy conditions (H-b < 0.25 m), while the convex-concave profile develops under higher energy conditions (H-b > 0.35 m). The concave profile takes an intermediate position. The influence of the micro-tidal cycle (mean range 0.21 m) on the beach face morphology is expressed by the exact position of the step and the berm crest. Slight variations of the three profile types develop under conditions of strong offshore winds resulting in eolian sediment transport towards the beach face and during high groundwater levels relative to sea-level leading to localized mid-beach face erosion caused by impermeability of this part of the beach face. Sedimentary structures were classified according to the observed morphologic zones in the beach face environment.

Mase, H., Random Wave Runup Height On Gentle Slope, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 115 (5), 649-661, 1989.


Mase, H., Frequency Down-Shift of Swash Oscillations Compared to Incident Waves, Journal of Hydraulic Research, 33 (3), 397-411, 1995.

The frequency down-shift of swash oscillations compared to incident waves is examined by laboratory experiments and numerical simulations in connection with the uprush-backwash interaction in the swash zone and the standing wave in the surf zone. The experimental and numerical results show that the interaction between uprush and backwash actually generates swash oscillations with the frequency lower than that of incident waves when the power of short waves or bores near the shoreline is large. When the power of the bores is weak, a group-induced standing wave is dominant in the swash oscillations.

Masselink, G., and B. Hegge, Morphodynamics of meso- and macrotidal beaches: Examples from central Queensland, Australia, Marine Geology, 129 (1-2), 1-23, 1995.

Detailed measurements of the morphology, waves, and longshore and cross-shore currents were conducted on two beaches on the low- to medium-energy, macrotidal coastline of central Queensland (Australia). Nine Mile Beach is characterised by a relatively steep upper profile, a low-gradient intertidal zone with one or two swash bars, transverse bar/rip morphology at low-tide level and a very low-gradient, dissipative subtidal zone. The beach is composed of fine to medium sand and experiences a modal wave height of 0.75 m and a mean spring- tide range of 3.6 m. Lambert's Beach possesses a steep, coarse- grained, reflective upper profile, and a low-gradient dissipative low tide terrace composed of fine to medium sand. Subdued rip channels intersect the low tide terrace and the beach is subject to a modal wave height of 0.6 m and a mean spring-tide range of 4.6 m. The two beaches are classified as Low Tide Bar/Rip and Low Tide Terrace beaches, respectively, following the model of Masselink and Short (1993). During the present investigation, the Low Tide Bar/Rip beach (Nine Mile Beach) exhibited a larger temporal variability than the Low Tide Terrace beach (Lambert's Beach), despite similar hydrodynamic conditions over the survey period. This difference is principally attributed to the differences in the beach morphologies and the types of morphological changes that occurred. On Nine Mile Beach, morphologic changes were primarily associated with secondary features (swash bars and low tide bar/rip system), whereas on Lambert's Beach the changes in morphology were largely the result of adjustments of the overall beach profile. A number of surf zone processes were investigated, including incident-wave attenuation, infragravity-wave energy, bed return flow and longshore currents. The influence of the tide on surf zone dynamics was found to be insignificant, except in the case of longshore currents. On Nine Mile Beach, the longshore current associated with the nearshore cell circulation was stronger during low tide. On Lambert's Beach, the shore-parallel current on the low tide terrace was largely driven by the tide. A beach profile zonation was defined for Nine Mile Beach and Lambert's Beach based on an examination of the varying influence of swash, surf zone and shoaling wave processes. The four-part tidal zonation consists of: (1) an upper intertidal zone across which swash and aeolian processes are the major influence; (2) a mid- intertidal zone dominated by swash and surf zone processes; (3) a lower intertidal zone controlled by surf zone and shoaling wave processes; and (4) a subtidal zone largely influenced by shoaling wave processes.

Masselink, G., B.J. Hegge, and C.B. Pattiaratchi, Beach cusp morphodynamics, Earth Surface Processes and Landforms, 22 (12), 1139-+, 1997.

Detailed measurements of three-dimensional beach cusp morphology were made on a steep gradient, low energy, microtidal beach in Perth, Western Australia. During the held campaign a variety of wave conditions and tidal ranges were experienced, and these differing hydrodynamic conditions were reflected in a consistent pattern of morphological changes to the beach cusp system. A useful parameter to delineate between trends of cusp destruction and re-formation appeared to be the surf similarity parameter xi=tan beta/root H-0/L-0, where H-0 is offshore wave height, L-0 is deep water wave length and tan beta is beach gradient. For xi<1.2 the beach cusps were planed off, whereas cusp morphology was enhanced when xi>1.2. A small storm was experienced at the start of the field campaign period and resulted in considerable erosion of the beach face. The cusp morphology across the lower beachface was destroyed, but a subtle remnant of the pre-storm cusp morphology was preserved on the upper beachface. When cusps reformed after the storm, under the influence of declining wave conditions, they appeared at the same location and with the same dimensions as the pre- storm cusp morphology. Hence, it is considered that the cusp re-formation was controlled more by the antecedent morphology than the hydrodynamic conditions. This indicates that positive feedback between swash hydrodynamics and beachface morphology, necessary to form beach cusps, does not require a large variation in relief. (C) 1997 John Wiley & Sons, Ltd.

Masselink, G., and M. Hughes, Field investigation of sediment transport in the swash zone, Continental Shelf Research, 18 (10), 1179-1199, 1998.

Concurrent measurements of swash flow velocity and sediment transport were obtained from a natural beach to develop a means for predicting sediment transport in the swash zone. Twenty- seven swash events were monitored and the sediment load of each event was correlated to the flow velocity for both the wave uprush and backwash. The sediment load displayed a strong relationship with the time-averaged velocity cubed, consistent with equations for both bedload transport and total load transport under sheet flow conditions. Validation of the energetics-based model of Bagnold (1963, 1966) revealed different constants of proportionality for wave uprush and backwash, with the uprush value being approximately twice that obtained for the backwash. Similarly, validation of a modified Shields parameter (to account for the effect of a sloping bed) also indicated different coefficients. The physical explanation for the different constants of proportionality is that neither sediment transport model adequately accounts for the disparate nature of the two phases of the swash cycle. (C) 1998 Elsevier Science Ltd. All rights reserved.

Masselink, G., and C.B. Pattiaratchi, Morphological evolution of beach cusps and associated swash circulation patterns, Marine Geology, 146 (1-4), 93-113, 1998.

A numerical model capable of simulating the motion of water particles on beach cusp morphology under the influence of an initial velocity and gravity is presented. The model indicates that the typical swash pattern on beach cusps is three- dimensional, with wave uprush diverging at the cusp horns resulting in concentrated backwash streams in the embayment. The degree of horn divergence is an increasing function of the parameter epsilon(S/lambda)(2), where epsilon quantifies the prominence of the beach cusps, S is the horizontal swash excursion length and lambda is the cusp spacing. The numerical experiments are supplemented with detailed field measurements of beach cusp morphological change. The field data include three types of morphological response, each characterised by a particular pattern of swash circulation, that can be delineated using epsilon(S/lambda)(2). When epsilon(S/lambda)(2) < 0.015, beach cusp morphology is large and/or subdued in relation to the swash length. Swash circulation is essentially two- dimensional (oscillatory flow) and results in steepening of the beachface and infilling of the cusp embayments. For epsilon(S/lambda)(2) = 0.015 to 0.15, wave uprush is deflected from the cusp horns and flows into the embayments where it exits in a concentrated backwash stream (horn divergent flow). The ensuing swash/backwash inequality reinforces cusp development and maintains existing cusp morphology. When epsilon(S/lambda(2) > 0.15, beach cusps are small and/or pronounced in relation to the length of the swash. Overtopping and pending of the cusp horn takes place and swash circulation is from the embayment to the horn thorn convergent flow). As a result, cusp horns are eroded and accretion occurs in the embayments. (C) 1998 Elsevier Science B.V. All rights reserved.

Masselink, G., and C. Pattiaratchi, Morphodynamic impact of sea breeze activity on a beach with beach cusp morphology, Journal of Coastal Research, 14 (2), 393-406, 1998.

Beach morphology and nearshore hydrodynamics were monitored over a number of sea breeze cycles on a beach with pronounced beach cusp morphology in southwestern Australia. The action of the sea breeze resulted in consistent changes to the incident wave field and beach cusp morphology, and induced a diurnal cycle of beach change. The morphological changes were accomplished without an apparent sediment gain or loss, but involved a redistribution of sediment within the cusp morphological system. During the sea breeze, the addition of locally-generated, short-period mind waves to the background swell resulted in an increase in wave height, a decrease in wave period and an intensification of the nearshore currents. The cusp morphology became increasingly subdued due to accretion in the embayment and, to a lesser extent, erosion of the horns. After the cessation of the sea breeze, the wind-wave energy level gradually decreased and the associated wind-wave period increased. Accretion on the cusp horns was accompanied by minor erosion of the embayment and resulted in an accentuation of the cusp morphology. The build-up of the cusp morphology was a consequence of the morpho dynamic feedback between the antecedent cusp morphology and the wave runup characteristics. The wave runup was diverted from the horn into the embayment, resulting in decreased backwash volumes and hence build-up of the horn. In the cusp embayment, increased backwash volumes resulted in scouring and the suppression of potential swash events at the base of the beachface. Consequently, the proportion of infragravity-wave energy in the runup record was larger in the embayment than on the horn. Ten hours after the sea breeze had stopped blowing, significant amounts of wind-wave energy were still present. It is suggested that these wind waves were generated a distance of almost 200 km south of the study area, implying that the presence of the local sea breeze may have regional implications for coastal processes.

Masselink, G., Alongshore variation in beach cusp morphology in a coastal embayment, Earth Surface Processes and Landforms, 24 (4), 335-347, 1999.

The variation in beach cusp characteristics was examined along a 1 km long embayed beach (Pearl Beach, New South Wales, Australia). The beach cusp morphology had formed during the previous day and/or night and displayed a marked alongshore variation in cusp spacing. The edge wave mechanism of beach cusp formation could not account for the observed trend in cusp spacing, because no relationship could be established between the spacing of the cusps and the gradient of the beachface. On the other hand, the cusp spacing was strongly related to the horizontal swash excursion, providing some support for the self-organization model of beach cusp formation. Copyright (C) 1999 John Wiley & Sons, Ltd.

Matsunaga, N., K. Takehara, and Y. Awaya, The Offshore Vortex Train, Journal of Fluid Mechanics, 276, 113-124, 1994.

A row of two-dimensional vortices forms in an offshore zone when regular surface waves run up a sloping flat bed. This vortex row is called the offshore vortex train. The vortices begin to appear near the breaking point. Moving in the offshore direction, they develop and increase their horizontal lengthscale through vortex merging. After reaching a particular offshore location, however, they decay rapidly. The formation region of the vortex train has been investigated on the basis of visual experiments for three bed slopes. Its formation does not depend on the type of wave breaking but is observed when the steepness of deep-water waves is smaller than 4.2 x 10(-2). The horizontal lengthscale of the vortices and the velocities of the vortex movement,have also been evaluated empirically.

McLachlan, A., J.E. Dugan, O. Defeo, A.D. Ansell, D.M. Hubbard, E. Jaramillo, and P.E. Penchaszadeh, Beach clam fisheries, in Oceanography and Marine Biology, Vol 34, pp. 163-232, 1996.

The biology, ecology, and fisheries of 15 species of clam from exposed ocean beaches are reviewed and contrasted. The species, representative of four families of bivalves, are Tivela stultorum and Siliqua patula from North America, Tivela mactroides, Donax denticulatus and D. striatus from the Caribbean, Mesodesma mactroides and M. donacium from southern South America, Donax trunculus from Europe, D. serra from southern Africa, D. cuneatus and D. faba from Asia, Donax deltoides from Australia, and Paphies ventricosa, P. subtriangulata and P. donacina from New Zealand. These clams tend to fall into two categories: generally larger temperate species that dominate the: macrofauna community biomass on beaches of the dissipative type, and generally smaller tropical species, mostly donacids, found on reflective beaches. Some species have intertidal distributions, but most are centred in the swash zone or shallow subtidal. Vertical distribution appears to be related to latitude and temperature with lower temperatures leading to a more downshore distribution. Subtidal species are more difficult to exploit because of the protection afforded by high energy surf zones. All are filter feeders, playing important roles in the trophic structure of beaches. Most species have extended spawning, often with two peaks in the year. In many cases recruitment occurs in a different zone from the adult populations with subsequent migration up or downshore. Life spans range from 1-3 yr for the smaller, warm water species to >20yr in the larger temperate species, but most species live for 2-8yr and have relatively rapid growth to maturity. Many populations exhibit resurgences-considerable fluctuations in abundance coupled to variable recruitment and/or mass mortalities. Exploitation of beach clams is sometimes constrained by the accumulation of toxins, such as those associated with blooms of toxic algae, that can render them unsafe for human consumption and may cause mass mortalities of the clams themselves. Many beach clam species support recreational, artisanal and commercial fisheries, hut recreational fisheries are also mostly commercial and, with a few notable exceptions, most of the commercial fisheries are also artisanal. Recreational fisheries are notoriously difficult to manage since numbers of harvesters cannot usually be controlled and exploitation must be limited solely by recourse to size, bag and season and/or area restrictions. The recreational experience provided by clam fisheries on ocean beaches must be considered to be as valuable as the food value of the resource itself.


Nadaoka, K., M. Hino, and Y. Koyano, Structure of the Turbulent-Flow Field Under Breaking Waves in the Surf Zone, Journal of Fluid Mechanics, 204, 359-387, 1989.


Nadaoka, K., H. Yagi, and H. Kamata, A Simple Quasi-3-D Model of Suspended Sediment Transport in a Nonequilibrium State, Coastal Engineering, 15 (5-6), 459-474, 1991.

A new simple model to evaluate quasi-3-D suspended sediment transport in a non-equilibrium state has been developed through a formulation based on a kind of weighted residual concept. The model includes only two unknown variables to be solved in a horizontal 2-D domain (x,y); i.e., the sediment concentration at the bottom C(b)(x,y,t) and the shape factor A(x,y,t) in the assumed exponential curve for the vertical profile of the concentration, both of which are the most important factors governing the nonequilibrium sedimentary process. From the computational results for the 1-D deposition and erosion problems, the model has been confirmed to give satisfactory results in accuracy and in computational time. The present model has also been applied to the 3-D suspended sediment transport problem in the nearshore region including the surf zone. The comparison between the computational results by the present model and those by the conventional models assuming the local equilibrium concentration profile and the nonequilibrium but vertically uniform profile, have demonstrated the importance of taking the effect of the nonequilibrium 3-D condition into the consideration for such problems.

Nadaoka, K., S. Beji, and Y. Nakagawa, A fully dispersive weakly nonlinear model for water waves, Proceedings of the Royal Society of London Series a- Mathematical Physical and Engineering Sciences, 453 (1957), 303-318, 1997.

A fully dispersive weakly nonlinear water wave model is developed via a new approach named the multiterm-coupling technique, in which the velocity field is represented by a few vertical-dependence functions having different wave-numbers. This expression of velocity, which is approximately irrotational for variable depth, is used to satisfy the continuity and momentum equations. The Galerkin method is invoked to obtain a solvable set of coupled equations for the horizontal velocity components and shown to provide an optimum combination of the prescribed depth-dependence functions to represent a random wave-field with diversely varying wave- numbers. The new wave equations are valid for arbitrary ratios of depth to wavelength and therefore it is possible to recover all the well-known linear and weakly nonlinear wave models as special cases. Numerical simulations are carried out to demonstrate that a wide spectrum of waves, such as random deep water waves and solitary waves over constant depth as well as nonlinear random waves over variable depth, is well reproduced at affordable computational cost.

Nadaoka, K., and H. Yagi, Shallow-water turbulence modeling and horizontal large-eddy computation of river flow, Journal of Hydraulic Engineering-Asce, 124 (5), 493-500, 1998.

By introducing the concept of "SDS (subdepth scale) turbulence" to model three-dimensional (3D) turbulence with length scales less than the water depth and treating it explicitly with a proper separate modeling, an SDS-2DH model has been developed to simulate the evolution of horizontal large-scale eddies in shallow water. Applying this model to river flows with transverse shear due to vegetation drag, the horizontal large- scale (HLS) eddies were found to dominate horizontal momentum mixing. The bottom friction and vegetation drag, acting as sinks of vorticity, play the key roles in the development of the horizontal large-scale eddies and in Reynolds stress generation. The SDS-2DH model can directly describe effects of flow geometry, such as vegetation layer width, on the large- scale eddy development and, hence, predicts turbulence-mixing better than the k-epsilon model.

Nielsen, P., N.R. Sena, and Z.J. You, The Roughness Height Under Waves, Journal of Hydraulic Research, 28 (5), 645-646, 1990.


Nittrouer, C.A., and L.D. Wright, Transport of Particles Across Continental Shelves, Reviews of Geophysics, 32 (1), 85-113, 1994.

Transport of particulate material across continental shelves is well demonstrated by the distributions on the seabed and in the water column of geological, chemical, or biological components, whose sources are found farther landward or farther seaward. This paper addresses passive (incapable of swimming) particles and their transport across (not necessarily off) continental shelves during high stands of sea level. Among the general factors that influence across-shelf transport are shelf geometry, latitudinal constraints, and the timescale of interest. Research studies have investigated the physical mechanisms of transport and have made quantitative estimates of mass flux across continental shelves. Important mechanisms include wind-driven flows, internal waves, wave-orbital flows, infragravity phenomena, buoyant plumes, and surf zone processes. Most particulate transport occurs in the portion of the water column closet to the seabed. Therefore physical processes are effective where and when they influence the bottom boundary layer, causing shear stresses sufficient to erode and transport particulate material. Biological and geological processes at the seabed play important roles within the boundary layer. The coupling of hydrodynamic forces from currents and surface gravity waves has a particularly strong influence on across-shelf transport; during storm events, the combined effect can transport particles tens of kilometers seaward. Several important mechanisms can cause bidirectional (seaward and landward) transport, and estimates of the net flux are difficult to obtain. Also, measurements of across-shelf transport are made difficult by the dominance of along-shelf transport. Geological parameters are often the best indicators of net across-shelf transport integrated over time scales longer than a mouth. For example, fluvially discharged particles with distinct composition commonly accumulate in the midshelf region. Across-shelf transport of particulate material has important implications for basic and applied oceanographic research (e.g., dispersal of planktonic larvae and particle- reactive pollutants). Continued research is needed to understand the salient mechanisms and to monitor them over a range of timescales.

Ohyama, T., and K. Nadaoka, Development of a Numerical Wave Tank For Analysis of Nonlinear and Irregular Wave Field, Fluid Dynamics Research, 8 (5-6), 231-251, 1991.

A numerical wave-absorption filter has been developed for an open boundary condition in the analysis of nonlinear and irregular wave evolution. The filter is composed of a simulated sponge layer and Sommerfeld's radiation condition at the outer edge of the layer. The wave-absorption characteristics of the filter have been investigated by applying the linear potential theory and a two-dimensional nonlinear boundary element model. In both cases, the filter is found to be applicable for a wide range of wave parameters. In order to realize an idealized "numerical wave tank", the present model also incorporates a nonreflective wave generator in the computational domain composed of a series of vertically aligned point sources. Numerous numerical experiments demonstrate that the present approach is effective in generating an arbitrary wave profile without reflection not only at the open boundaries but also at the wave generator.

Ohyama, T., and K. Nadaoka, Transformation of a Nonlinear-Wave Train Passing Over a Submerged Shelf Without Breaking, Coastal Engineering, 24 (1-2), 1-22, 1994.

The decomposition phenomenon of a nonlinear wave train passing over a submerged shelf without breaking has been investigated by a previously developed numerical model. The computed wave profiles at various locations agree favorably with experimental observations. This phenomenon is triggered by higher harmonic generation and nonlinear resonant interaction over the shelf. In the case of a strongly nonlinear wave field over the shelf, the resultant beat length of higher harmonic amplitudes cannot be properly described by weakly nonlinear solutions, in which the linear dispersion relation is employed for free waves. A large amount of energy in bound harmonics over the shelf is abruptly transferred into free higher harmonics in the trailing side of the shelf, where a second-order theory markedly overestimates the first- and the second-harmonic amplitudes. Variations of the decomposition characteristic between the shelf's configuration and the incident wave conditions are also investigated. When the width of the shelf is nearly one half of the beat length of a higher harmonic amplitude, the magnitude of the corresponding component becomes remarkably large in transmitted waves. In the case of large incident waves, significant decomposition takes place even when the shelf is deeply submerged. In addition, the transformation of multicomponent random waves has been studied. The results show that nonlinear interaction among the incident wave components also generates distinct higher harmonics. The power spectrum of the transmitted wave is found to be significantly influenced by the phase differences among the incident components.

Ohyama, T., S. Beji, K. Nadaoka, and J.A. Battjes, Experimental-Verification of Numerical-Model For Nonlinear-Wave Evolutions, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 120 (6), 637-644, 1994.


Oltmanshay, J., P.A. Howd, and W.A. Birkemeier, Shear Instabilities of the Mean Longshore-Current .2. Field Observations, Journal of Geophysical Research-Oceans, 94 (C12), 18031-18042, 1989.


Orford, J.D., and R.W.G. Carter, Examination of Mesoscale Forcing of a Swash-Aligned, Gravel Barrier From Nova-Scotia, Marine Geology, 126 (1-4), 201-211, 1995.

The possibility by which the retreat of a swash-aligned, gravel barrier on Nova Scotia's Atlantic coast may be influenced by varying mesoscale time domains of differential process conditions is examined. Tide gauge data are used to generate definition of mesoscale process domains regarded as influential in barrier behaviour. Semi-diurnal, high-water tidal residuals from Halifax (Nova Scotia) tide gauge (1920-1990) are characterised for both surge magnitude and frequency on an annual basis. These two variables are combined to define three event types of annual surge histories. First-order, nth-step Markov analyses show that significant memory exists in 6-year and 22-year transitions between surge event types. The longer transition sequence mirrors a major decadal mesoscale domain change in surge generation which is suggested to be associated with phases of barrier crest reworking that enhance barrier retreat when the domain change occurs. The shorter transition sequence may reflect cyclonic activity cycles on the Scotian Shelf superimposed on the longer-term transition.

Orford, J.D., R.W.G. Carter, J. McKenna, and S.C. Jennings, The Relationship Between the Rate of Mesoscale Sea-Level Rise and the Rate of Retreat of Swash-Aligned Gravel-Dominated Barriers, Marine Geology, 124 (1-4), 177-186, 1995.

In theory, a rise in sea level should force swash-aligned gravel-barriers to retreat landwards. Evidence from three single-crested, swash-aligned gravel barriers from eastern Canada and northwest Europe indicates that barrier-retreat rate correlates with the rate of sea-level rise measured over the lower end of the mesoscale time spectrum (subdecadal: 10(0) yr- 10(1) yr). There is also a relationship between a barrier's rate of change in retreat rate and the decadal mesoscale mean rate of sea-level rise (specified by the duration of the tide- gauge record: 10(1) yr-10(2) yr). Specifically, the higher the decadal mesoscale sea-level rise rate the faster the rate of retreat of the swash-aligned gravel barrier. However, this latter relationship may also be a function of the barrier's inertia as defined by the barrier's cross-sectional volume in that barrier retreat rate correlates negatively with barrier inertia.

Orford, J.D., R.W.G. Carter, and S.C. Jennings, Control domains and morphological phases in gravel-dominated coastal barriers of Nova Scotia, Journal of Coastal Research, 12 (3), 589-604, 1996.

Gravel dominated barriers are a major coastal feature of mid and upper latitudes indicating the active sorting of heterogeneous glacigenic sediments by wave action. Research over the last decade has suggested a sequential process for the development of gravel-dominated barrier coasts along the Atlantic coast of Nova Scotia. Controls on the development of gravel-dominated barriers are sediment supply, sea-level change, terrestrial basement geometry and wave climate. The variable interaction of these controls is shown to define distinctive process domains in which phases of barrier morphology develop. Sediment supply in its control on barrier alignment and barrier breakdown, is suggested as the most important of these variables for between-variation in the Nova Scotia barriers. Long-term (10a(3)) sea-level change controls the tempo of the transgression and thereby regulate macro- longshore sediment supply. Shortterm (<10a) sea-level rise may be influential in the rate of barrier breakdown. Barriers can be assigned by morphological structure to one of four main types of domains; growth, consolidation, breakdown and reformation. Some domains show different phases; growth has an inception phase and growth phase; breakdown has slow rollover, fast rollover and dissolution phases. Barriers may exhibit elements of several phases at the same time. Whether the phases are regarded as evolutionary is debated. The idea of phases being considered as the result of indeterminate activity is presented.

Osborne, P.D., and E.H. Boak, Sediment suspension and morphological response under vessel- generated wave groups: Torpedo Bay, Auckland, new Zealand, Journal of Coastal Research, 15 (2), 388-398, 1999.

Waves, currents, suspended sediments and beach morphological response were measured using fast-response sensors over a 13 month period at Torpedo Bay, Auckland to evaluate the relative effects of vessel generated waves (VGW) and wind generated waves (WGW). WGW (H-s = 0.1-0.2 m, T-pk = 1-2 s) are severely limited by the maximum unrestricted fetch of only 2.5 km at this location. In contrast, VGW reach maximum heights in excess of 0.85 m, have an average H-s similar to 0.3 m and periods of 2-6 s on the foreshore. The groupiness and nonlinear form of these large VGW makes them capable of entraining and suspending significant quantities of bottom sediment (concentrations reaching 10-100 g l(-1)) resulting in sustained increases of turbidity in the nearshore region. VGW represent a significant proportion of the total energy available to transport sediment at Torpedo Bay, contributing as much as twice the sediment transport potential relative to wind-generated waves. Sand resuspension events under non-linear (asymmetric and skewed) shoaling and breaking VGW exhibit a distinctive temporal structure. This structure is characterised by a marked instantaneous response to sharp accelerations, high velocities and intense turbulence under the crests of asymmetric breaking waves and also by a gradual accumulation and decay of suspended sediment in the water column. The former feature leads to net onshore transport while the latter feature leads to both a distinctive phase lag between the largest VGW and the event maximum suspended sediment concentration (SSC), and to the enhancement of turbidity in the nearshore. Despite short term fluctuations in bed elevation of up to +/- 10 cm in response to large VGW and relatively high gross sediment transport, the net effect of both WGW and VGW on the sediment transport and foreshore response at Torpedo Bay appears to be insignificant.

Osborne, P.D., and G.A. Rooker, Sand re-suspension events in a high energy infragravity swash zone, Journal of Coastal Research, 15 (1), 74-86, 1999.

Suspended sediment concentration (SSC), fluid velocity and morphological response were measured on the foreshore of a high energy dissipative beach west of Auckland, New Zealand. Swash re-suspension events exhibit a distinct temporal structure associated with both the uprush and backwash phases. SSC of >50 gl(-1) is associated with large accelerations, turbulence, and high flow speeds in shallow water under shoreward propagating swash bores. SSC decreases rapidly from the initial peak and then more gradually as water depth increases to a maximum at the end of the uprush SSC increases gradually as the backwash accelerates, and then reaches a peak under the rapidly thinning and accelerating flow near the end of the backwash. Flows are super-critical, hydraulic jumps occur and unstable anti-dune bedforms often develop near the end of backwash events resulting in sharp increases in SSC. Event averaged SSC declines systematically as maximum depth of swash increases. Peak SSC tends to be larger under uprush events than backwash events particularly near the margins of the swash zone. Cross- spectral analysis of velocity and SSC at the transition between the inner surf zone and swash zone confirms that the dominant transport occurs at infragravity frequencies. Net transport is potentially sensitive to small variations in the phase angle between SSC and velocity in the uprush and backwash cycle as well as to the variability in bed conditions during swash cycles.

Pattiaratchi, C., B. Hegge, J. Gould, and I. Eliot, Impact of sea-breeze activity on nearshore and foreshore processes in southwestern Australia, Continental Shelf Research, 17 (13), 1539-1560, 1997.

In coastal regions sheltered from the direct impact of swell- and storm-wave activity, locally generated wind waves, particularly those associated with strong sea-breeze activity, play a dominant role in controlling nearshore and foreshore processes. Field data collected from the Perth Metropolitan Coast (western Australia) during a typical summer sea-breeze cycle, are presented. It is demonstrated that the nearshore environment responds rapidly to an increase in wind speed (up to 12 m s(-1)) during the sea breeze, resulting in considerable changes to the nearshore hydrodynamics and morphology. Incident wave energy increased during the sea breeze and was associated with development of a wind-wave field with significant wave heights up to 0.9 m. Nearshore currents responded to this change in wave climate with the development of net offshore near-bed currents and a rapid increase in the mean longshore current from <0.05 m s(-1) to 1.0 m s(-1). A 10-fold increase in suspended sediment concentration and a 100-fold increase in the longshore sand transport resulted from the effects of the sea-breeze system. Erosion of the beachface was coincident with the development of the wind-wave held. Sea breeze wave-driven water circulation also completely eroded beach cusps (wavelength 20-30 m), overwhelmed the rip current system associated with the beach cusps and suppressed the infra- gravity wave frequencies in the incident wave and swash record. The beach cusps reformed after the cessation of the sea breeze. It is demonstrated that the beachface is in a constant stage of adjustment to the incident wave energy through the diurnal sea- breeze cycle alternating between dissipative and reflective morphodynamic regimes. The results may be used to determine the impact of a medium-sized storm on the beachface. It is clear that the sea-breeze system plays a major role in controlling the nearshore and foreshore processes not only in this region, but also on other geographic locations where strong sea breezes are present. (C) 1997 Elsevier Science Ltd. All rights reserved.

Pedersen, C., R. Deigaard, J. Fredsoe, and E.A. Hansen, Simulation of Sand in Plunging Breakers, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 121 (2), 77-87, 1995.

A numerical model that simulates the sediment transport due to plunging breaking waves has been developed. A plunging breaker is simulated by superimposing a jet on a nonbreaking wave. The hydrodynamics are described by applying a discrete vortex model based on the mixed Eulerian-Lagrangian description of the cloud-in-cell method. Rotation is introduced in the flow where the jet impinges on the surface and in the boundary layer along the bottom. A combined diffusion-convection procedure provides a Lagrangian description of the suspended sediment. The pickup and initial suspension event in the boundary layer is simulated by a diffusion process, while the transport in the outer flow domain is simulated by convection, using the flow field provided by the hydrodynamic module. The bed-load transport is calculated by a conventional formula that relates the transport rate to the Shields parameter. A simulation over a complex bottom topography is compared to the full-scale laboratory experiments performed by Dette and Uliczka in 1986. The calculated and measured time-averaged concentration profiles show good agreement both with respect to the overall concentration levels and the cross-shore distribution.

Plant, N.G., and R.A. Holman, Intertidal beach profile estimation using video images, Marine Geology, 140 (1-2), 1-24, 1997.

In this paper, we present a technique suitable for measurement of intertidal bathymetry over a broad range of length scales (10(1) to 10(3) m) and time scales (days to decades). A series of time-averaged images of the swash zone are used to map contour lines of the beach surface. In each image, contours are identified using bands of maximum brightness associated with breaking waves at the shoreline. By mapping the location of these bands in a sequence of images collected over one tidal cycle, contour maps of the intertidal bathymetry are generated. We expect this technique to work best (smallest absolute error) under waves which are nearly reflective at the shoreline, but break enough to be observed visually. This is typical of a barred beach since the wave height at the shoreline is limited by wave breaking over the bar crest. The ability of the measurements made with this technique to resolve actual beach elevation variation depends on the ratio of the measurement error variance to the true beach elevation variance. Thus, large measurement errors may be compensated by either large tidal ranges or large temporal changes of the beach itself. In a comparison to bathymetry surveyed using a Differential Global Positioning System (DGPS) during the Duck94 experiment, in Duck, N.C., the image-based elevation estimates were well correlated with the actual bathymetry. The deviations (image- based vs. DGPS measurements) may be partially attributed to effects scaled by wave height at the shoreline, wave-induced setup, and wave height saturation over the sand bar. In particular, setup was important during dissipative conditions. The rms deviation (vertical) between the DGPS and image-based bathymetry was reduced from 0.24 m to 0.06 m by correcting for the systematic deviations due to variations in setup and wave height saturation. Further improvement of the elevation estimates resulted from parameterizing the actual bathymetry with a simple plane beach surface, which reduced random (or unresolvable) measurement errors. This led to estimates of the beach slope that were accurate to within 10% of the actual slope and estimates of the cross-shore location of the mean sea level line accurate to about 0.50 m. (C) 1997 Elsevier Science B.V.

Putrevu, U., and I.A. Svendsen, Infragravity Velocity Profiles in the Surf Zone, Journal of Geophysical Research-Oceans, 100 (C8), 16131-16142, 1995.

We present a theoretical solution for the vertical structure of the velocity profiles in infragravity waves. The solution predicts that while the velocity without local forcing of the infragravity waves does not vary significantly with the vertical coordinate, the velocity with local forcing of the infragravity waves has a substantial vertical structure.

Pyokari, M., The provenance of beach sediments on Rhodes, southeastern Greece, indicated by sediment texture, composition and roundness, Geomorphology, 18 (3-4), 315-332, 1997.

The texture, composition, provenance, and transport of beach sediments and the roundness of sediment grains were studied on the coasts of the island of Rhodes in southeastern Greece. All the studied beaches are intermediate or high-carbonate beaches where the texture and mineral composition of beach sediments and roundness of sediment grains display some degree of local variation. Beach sediments consist mainly of medium and coarse sand and granule gravel, being moderately or poorly sorted, symmetrical or negatively skewed and leptokurtic or very leptokurtic. On pocket beaches the mineral composition is closely related to nearby exposed coastal formations (sea cliffs, bluffs and rocks), the grain-size frequency distributions of beach sediments being nearly normal, and the roundness of sediment grains good. Where rivers discharge on to the beach or near to it, the mineral content of these beaches is-related both to the formations situated inland in the catchment basins of the rivers and to coastal formations. River sediments (55-60%) and coastal abrasion sediments (40-45%) on shores are mixed by waves and littoral drift. Low-Mg calcite and quartz are the most common minerals in the beach sediments of Rhodes. The other common minerals are dolomite, feldspars, olivine, and magnetite; the sources being mainly the ophiolites on the mountains of northern Rhodes. The direction of net littoral drift is determined mainly by the predominant wind and waves approaching from the direction of the greatest fetch. These same waves determine, to a large extent, the direction of seasonal littoral drift in the beach and swash zones, whereas in the surf zone on the NW coast of Rhodes, it is determined mainly by the prevailing wind and waves.

Pyokari, M., Beach sediments of Crete: Texture, composition, roundness, source and transport, Journal of Coastal Research, 15 (2), 537-553, 1999.

The texture, composition, provenance, and transport of beach sediments and the roundness of sediment grains were studied on 22 beaches on the coasts of Crete in southern Greece. The studied beaches range from low-carbonate to high-carbonate beaches, where the texture and mineral composition of beach sediments and roundness of sediment grains display some degree of local variation. Beach sediments consist mainly of medium and coarse sand, being moderately well or well-sorted, symmetrical or negatively skewed and mesokurtic or leptokurtic. On beaches where no rivers enter the sea the mineral composition is closely related to nearby exposed coastal formations (sea cliffs, bluffs and rocks), the grain-size frequency distribution of beach sediments being nearly normal, and the roundness of sediment grains rather good. Where rivers discharge on to the beach or near to it, the mineral content of these beaches is related both to the coastal formations and the formations situated inland in the catchment basins of the rivers. Coastal abrasion and fluvial sediments on shores are mixed by waves and littoral drift, causing somewhat poorer sorting and roundness. Low-Mg calcite and quartz are the most common minerals (altogether 50-90%) in the beach sediments on Crete. The other common minerals are dolomite, feldspars, epidotes, pyroxenes, amphiboles, tourmaline, zircon, titanite and magnetite; the sources being mainly dolomites, phyllite- quartzites, ophiolites, flysch, and sandstones on the mountains and coasts of Crete. The direction of net littoral drift is determined mainly by the predominant wind and waves approaching from the direction of the greatest fetch, while the onshore Rinds and waves (the directions of the fetches arranged according to the length of the fetch) greatly determine the direction of seasonal littoral drift. These two wind factors together determine, to the large extent, the direction of seasonal littoral drift in the surf zone, whereas in the swash zone the direction is determined only by the onshore winds and waves. On the other hand, the prevailing wind and waves have a little effect on the direction of sediment movement on the coasts of Crete.

Rajopadhye, S.V., Propagation of Bores in Incompressible Fluids, International Journal of Modern Physics C-Physics and Computers, 4 (3), 621-699, 1993.


Raubenheimer, B., R.T. Guza, S. Elgar, and N. Kobayashi, Swash On a Gently Sloping Beach, Journal of Geophysical Research-Oceans, 100 (C5), 8751-8760, 1995.

Waves observed in the inner surf and swash zones of a fine grained, gently sloping beach are modeled accurately with the nonlinear shallow water equations. The model is initialized with observations from pressure and current sensors collocated about 50 m from the mean shoreline in about 1 m depth, and model predictions are compared to pressure fluctuations measured at five shoreward locations and to run-up. Run-up was measured with a vertical stack of five wires supported parallel to and above the beach face at elevations of 5, 10, 15, 20, and 25 cm. Each 60-m-long run-up wire yields time series of the most shoreward location where the water depth exceeds the wire elevation. As noted previously, run-up measurements are sensitive to the wire elevation owing to thin run-up tongues not measured by the more elevated wires. As the wire elevation increases, the measured mean run-up location moves seaward, low-frequency (infragravity) energy decreases, and higher- frequency sea swell energy increases. These trends, as well as the variation of wave spectra and shapes (e.g., wave skewness) across the inner surf zone, are well predicted by the numerical model.

Raubenheimer, B., and R.T. Guza, Observations and predictions of run-up, Journal of Geophysical Research-Oceans, 101 (C11), 25575-25587, 1996.

For a significant range of offshore wave conditions and foreshore slopes, run-up observations are compared to semiempirical formulations and predictions of an existing numerical model based on the depth-averaged one-dimensional nonlinear shallow water equations with bore-like breaking wave dissipation and quadratic bottom friction. The numerical model is initialized with time series of sea surface elevation and cross-shore velocity observed in 80 cm mean water depth (approximately 50 m offshore of the mean shoreline) on a gently sloping beach and in 175 cm water depth (100 m offshore of the shoreline) on a steep concave beach. Run-up was measured with a stack of resistance wires at elevations 5, 10, 15, 20, and 25 cm above and parallel to the beach face. At sea swell frequencies (nominally 0.05 < f less than or equal to 0.18 Hz), run-up energy is limited by surf zone dissipation of shoreward propagating waves so that increasing the offshore wave height above a threshold value does not substantially increase the predicted or observed sea swell run-up excursions (e.g., run-up is ''saturated''). Existing semiempirical saturation formulations are most consistent with the observations and numerical model predictions of run-up excursions nearest the bed. In contrast, at infragravity frequencies (0.004 < f less than or equal to 0.05 Hz) where surf zone dissipation is relatively weak and reflection from the beach face is strong (e.g., saturation formulas are not applicable), the run-up excursions increase approximately linearly with increasing offshore wave height. The numerical model also accurately predicts that the tongue-like shape of the run-up results in sensitivity of run-up measurements to wire elevation. For instance, run-up excursions and mean vertical superelevation (above the offshore still water level) increase with decreasing wire elevation, and continuous thinning of the run-up tongue during the wave uprush can result in large phase differences between run-up excursions measured at different wire elevations. Numerical model simulations suggest that run-up measured more than a few centimeters above the bed cannot be used to infer even the sign of the fluid velocities in the run- up tongue.

Raubenheimer, B., R.T. Guza, and S. Elgar, Wave transformation across the inner surf zone, Journal of Geophysical Research-Oceans, 101 (C11), 25589-25597, 1996.

Sea and swell wave heights observed on transects crossing the mid and inner surf zone on three beaches (a steep concave-up beach, a gently sloped approximately planar beach, and a beach with an approximately flat terrace adjacent to a steep foreshore) were depth limited (i.e., approximately independent of the offshore wave height), consistent with previous observations. The wave evolution is well predicted by a numerical model based on the one-dimensional nonlinear shallow water equations with bore dissipation. The model is initialized with the time series of sea surface elevation and cross-shore current observed at the most offshore sensors (located about 50 to 120 m from the mean shoreline in mean water depths 0.80 to 2.10 m). The model accurately predicts the cross-shore variation of energy at both infragravity (nominally 0.004 < f less than or equal to 0.05 Hz),nd sea swell (here 0.05 < f less than or equal to 0.18 Hz) frequencies. In models of surf zone hydrodynamics, wave-energy dissipation is frequently parameterized in terms of gamma(s), the ratio of the sea swell significant wave height to the local mean water depth. The observed and predicted values of gamma(s) increase with increasing beach slope beta and decreasing normalized (by a characteristic wavenumber k) water depth kh and are well correlated with beta/kh, a measure of the fractional change in water depth over a wavelength. Errors in the predicted individual values of gamma(s) are typically less than 20%. It has been suggested that infragravity motions affect waves in the sea swell band and hence gamma(s), but this speculation is difficult to test with field observations. Numerical simulations suggest that for the range of conditions considered here, gamma(s) is insensitive to infragravity energy levels.

Raubenheimer, B., S. Elgar, and R.T. Guza, Estimating wave heights from pressure measured in sand bed, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 124 (3), 151-154, 1998.

Comparison of predicted with observed attenuation of pressure fluctuations shows that wave heights can be estimated with observations from a pressure sensor that is buried a known depth in fine sand. The attenuation of pressure fluctuations within the sand bed under unbroken shoaling waves, bores in the surf zone, and swash near the shoreline was measured with vertical stacks of buried pressure sensors. The attenuation increased with increasing frequency and depth below the bed surface, consistent with previous observations under nonbreaking waves in deeper water and with model predictions based on pore-elastic theory, in the limit of an infinitely deep soil skeleton that is much more compressible than the pore fluid, the predicted pressure fluctuations decrease exponentially with increasing burial depth, and the attenuation is independent of the sediment properties. For the fine-grained sand beds considered here, this exponential limit accurately predicts the observed attenuation.

Roep, T.B., C.J. Dabrio, A.R. Fortuin, and M.D. Polo, Late highstand patterns of shifting and stepping coastal barriers and washover-fans (late Messinian, Sorbas Basin, SE Spain), Sedimentary Geology, 116 (1-2), 27-56, 1998.

The late Messinian Sorbas Member, up to 75 m thick, consists in its type area of a parasequence set of three prograding coastal barriers (sequences I-III), associated with lagoon and washover sediments. Around the town of Sorbas these strata can be studied exceptionally well due to absence of burrowing by raised Messinian salinities and exposure along a network of up to 30 m deep canyons. Fifteen vertical sections were logged and carefully correlated. This permits to reconstruct and discuss patterns of relative sea-level movements between decimetres, up to 15 m within a parasequence. Excellent examples of non-tidal transgressive facies are characterized by lagoon and washover sediments instead of the usual combination of washover and tidal deposits (channel and flood-tidal delta). Implications for the sandstone connectivity are given. The lower two sequences are deposited in a relatively large, tectonically enhanced wedge-shaped accommodation space. They show both fining-up, deepening sequences, followed by prograding coarsening-up shoaling sequences and can be compared to the classical parasequences of the Western Interior Basin (USA). Progradation of sequence II was interrupted by a major slide event (most likely triggered by an earthquake), which caused more than 400 m seaward slumping of a stretch of 1 km of coastal sands. The architecture of sequence III is more complex due to limited accommodation space characteristic for the late highstand, so that this setting was very sensitive to sea-level fluctuations. This resulted in an intricate pattern of juxtaposed and superposed lagoonal muds, washover fans and swash zones. So-called 'stranded' coastal barriers occur, which were left behind after seaward jump of the coastline over more than 1.5 km during forced regression. The pattern of reconstructed sea-level positions is well comparable to the sequential pattern shown by the correlated equivalents along the northern basin margin, which belong to the so-called Terminal Carbonate Complex. The problem of ranking the complex sequence III as one or more parasequences and its consequences for cyclostratigraphy are shortly discussed. Two models of washover formation are given, respectively during more rapid and more slow sea-level rise. The influence of synsedimentary folding on the location of barriers is discussed and also the source area of extra-and intraclasts supplied to barriers and washovers. After deposition of the Sorbas Member the sea withdrew from the Sorbas Basin, probably as a result of the major downdrop in the Mediterranean at the maximum isolation during the Salinity Crisis. It is suggested that the semi- enclosed setting of the basin resulted only in limited, localized erosion, in contrast to the deeper adjacent Vera Basin, which was more open to the Mediterranean. (C) 1998 Elsevier Science B.V. All rights reserved.

Ruessink, B.G., The temporal and spatial variability of infragravity energy in a barred nearshore zone, Continental Shelf Research, 18 (6), 585-605, 1998.

Recordings of near-bottom pressure at six cross-shore positions in a gently sloping multiple bar system were analysed to study the temporal and spatial variability of infragravity (0.004- 0.04 Hz) energy. The temporal variations in infragravity levels at each position were, as expected, strongly related to those in the offshore incident wave energy. Furthermore, infragravity energy was better correlated to swell than to sea energy and, under non-breaking conditions, was tidally modulated with larger values during low water than during high water. During low-energy conditions infragravity energy was almost constant over the profile, suggesting a dominance of free long-wave motions; however, it rapidly grew in the onshore direction during more energetic, though non-breaking conditions, caused by significant bound-wave contributions to the total long-wave held. Infragravity energy was significantly damped under surf- zone conditions, even causing a decline in the onshore direction. The data indicates that the release of hound long waves during the breaking process of the incident sea and swell may be the main source of free infragravity motions. (C) 1998 Elsevier Science Ltd. All rights reserved.

Ruessink, B.G., M.G. Kleinhans, and P.G.L. van den Beukel, Observations of swash under highly dissipative conditions, Journal of Geophysical Research-Oceans, 103 (C2), 3111-3118, 1998.

Video measurements of swash were made at the low-sloping beach of the multiple bar system at Terschelling, Netherlands. The majority of the measurements were conducted under highly dissipative conditions with Iribarren numbers xi(0) (the ratio of beach slope to the square root of offshore wave steepness) less than 0.2. Infragravity (0.004 - 0.05 Hz) waves dominated the swash with an average ratio of infragravity and total swash height R-ig/R of 0.85. Using linear regression we investigated the dependence of swash parameters on environmental conditions such as short-wave height, period, and local beach slope. On average, R-ig was about 30% of the offshore wave height H-0; the slope in the linear H-0 dependence of R-ig amounted to only 0.18, considerably smaller than that observed on steeper beaches. The data set shows evidence for saturation of the higher infragravity frequencies for xi(0) less than, roughly, 0.27. In our opinion, this saturation caused the constant of proportionality in the linear relationship between R-ig/H-0 and xi(0) to be significantly larger than that observed under higher Iribarren number regimes. The saturated tails of the swash spectra had an approximate f(-3) roll-off (where f is frequency), whereas, in general, the nonsaturated parts were white. This lack of significant peaks casts doubt on the causality between infragravity waves and nearshore bars.

Sakurai, I., M. Seto, and S. Nakao, Effects of water temperature, salinity and substrata on burrowing behaviors of the three bivalves, Pseudocardium sachalinensis, Mactra chinensis, and Ruditapes philippinarum, Nippon Suisan Gakkaishi, 62 (6), 878-885, 1996.

This paper analyzed the effects of water temperature, salinity and particle size of the substratum on the burrowing behaviors of the three Veneroid bivalves, Pseudocardium sachalinensis, Mactra chinensis, and Ruditapes philippinarum. The starting time for burrowing behavior (STBB) and mean burrowing velocity (MBV) of the three bivalves in 15-25 degrees C tended to be more rapid than those in 5-10 degrees C. In 5-10 degrees C, STBB and MBV of P. sachalinensis were the most rapid, and the burying depth of this species in 5-10 degrees was deeper than that in 15-25 degrees C. In R. philippinarum, the ranges of optimum salinity and particle size for burrowing were wide compared with the other species. It was concluded that the burrowing behaviors of P. sachalinensis and R. philippinarum are well adapted to the dynamic swash conditions in high latitudes and to sites with fresh water, fluctuation of water temperature and low sorting sediment.

Sallenger, A.H., and R.A. Holman, Infragravity Waves Over a Natural Barred Profile, Journal of Geophysical Research-Oceans, 92 (C9), 9531-9540, 1987.


Schaffer, H.A., and I.G. Jonsson, Edge Waves Revisited, Coastal Engineering, 16 (4), 349-368, 1992.

For edge waves on an infinite beach of constant slope comparison is made between the full linear solution and the shallow water approximation. Modifications to the shallow- water edge-wave dispersion relation accounting for an offshore shelf are obtained and compared with an earlier approximation. A physically comprehensible description of edge waves is given, using a geometrical optics approach, leading to approximate expressions for their dispersion relation. Both shallow water and general depth are considered. For the shallow water case comparison is made with the exact relation for an exponentially seaward decreasing slope. Finally the maximum possible edge wave amplitude is estimated by heuristic arguments.

Schaffer, H.A., Infragravity Waves Induced By Short-Wave Groups, Journal of Fluid Mechanics, 247, 551-588, 1993.

A theoretical model for infragravity waves generated by incident short-wave groups is developed. Both normal and oblique short-wave incidence is considered. The depth- integrated conservation equations for mass and momentum averaged over a short-wave period are equivalent to the nonlinear shallow-water equations with a forcing term. In linearized form these equations combine to a second-order long- wave equation including forcing, and this is the equation we solve. The forcing term is expressed in terms of the short-wave radiation stress, and the modelling of these short waves in regard to their breaking and dynamic surf zone behaviour is essential. The model takes into account the time-varying position of the initial break point as well as a (partial) transmission of grouping into the surf zone. The former produces a dynamic set-up, while the latter is equivalent to the short-wave forcing that takes place outside the surf zone. These two effects have a mutual dependence which is modelled by a parameter kappa, and their relative strength is estimated. Before the waves break the standard assumption of energy conservation leads to a variation of the radiation stress, which causes a bound, long wave, and the shoaling bottom results in a modification of the solution known for constant depth. The respective effects of this incident bound, long wave and of oscillations of the break-point position are shown to be of the same order of magnitude, and they oppose each other to some extent. The transfer of energy from the short waves to waves at infragravity frequencies is analysed using the depth- integrated conservation equation of energy. For the case of normally incident groups a semi-analytical steady-state solution for the infragravity wave motion is given for a plane beach and small primary-wave modulations. Examples of the resulting surface elevation as well as the corresponding particle velocity and mean infragravity-wave energy flux are presented. Also the sensitivity to the variation of input parameters is analysed. The model results are compared with laboratory experiments from the literature. The qualitative agreement is good, but quantitatively the model overestimates the infragravity wave activity. This can, in part, be attributed to the neglect of frictional effects.

Schaffer, H.A., P.A. Madsen, and R. Deigaard, A Boussinesq Model For Waves Breaking in Shallow-Water, Coastal Engineering, 20 (3-4), 185-202, 1993.

A simple description of wave breaking in shallow water is incorporated in the Boussinesq equations by using the concept of surface rollers. The roller is considered as a volume of water being carried by the wave with the wave celerity. The effect vf the roller is included in the vertical distribution of the horizontal velocity, which leads tn an additional convective momentum term. The breaking criterion is related to the local slope of water surface and the thickness of the roller is determined from simple geometrical considerations. Although the model is simple, it is capable of representing a variety of processes such as the initiation and cessation of wave breaking, the evolution of wave profiles before,, during and after wave breaking, the initial conversion of potential energy into forward momentum flux, and the associated horizontal shift between the break point and the point where the setup in mean water level is initiated. Results are presented for regular and irregular wave trains and comparison with measurements shows good agreement.

Schonfeldt, H.J., On the Modification of Edge Waves By Longshore Currents, Continental Shelf Research, 15 (10), 1213-1220, 1995.

On natural, barred beaches edge waves with frequencies within the range of the wind-wave frequencies are found to be trapped on the bar. For edge waves travelling in the direction of a longshore current, the onset of trapping is shifted to lower frequencies. The frequency range where the waves are trapped on the bar becomes greater and the waves in this range exhibit larger amplitudes offshore than at the shoreline. Furthermore, the most distant offshore antinode trapped on a bar increases its amplitude under the influence of longshore currents for edge waves travelling with the current. The objective of this note is to elucidate some new aspects of the impact of a natural seabed profile in the presence of longshore current.

Shih, S.M., and P.D. Komar, Sediments, Beach Morphology and Sea Cliff Erosion Within an Oregon Coast Littoral Cell, Journal of Coastal Research, 10 (1), 144-157, 1994.

The 24-km long beach of the Lincoln City littoral cell on the central Oregon coast is bound by pronounced headlands that prevent bypassing of beach sands, in effect making this a large pocket beach There is a seasonal reversal in the sand transport along this embayed shoreline, but the net littoral drift is zero. The wave energy is extreme, with storms generating 7- meter significant wave breaker heights. This wave energy is essentially uniform along the Lincoln City littoral cell; in spite of this uniformity, there is a marked longshore variation in grain sites of the beach sediments and an accompanying change in beach morphology from dissipative to reflective benches. These variations in the bench sediment grain sizes parallel those found in the sea cliffs which consist of Pleistocene bench and dune deposits apparently formed in environments similar to those found today. Gravel and coarse- sand layers are exposed in the sea cliff along the south central portion of the littoral cell, and these constitute the major source of coarser sizes in the modern beach. By dissecting the multimodal grain-size distributions of bench sediments into individual modes having log-normal distributions, we have been able to trace the coarse modes back to their sea cliff sources. The proportions of these modes within the bench rapidly decrease away from their sources indicating a relatively small degree of longshore dispersal in spite of the high-energy wave environment The persistence of the dispersal pattern suggests a period of time that has been insufficient to produce the longshore homogenization of the sediments, it is suggested that the sea cliff erosion which introduces the coarse modes into the bench sediments did not begin or was insignificant until about 300 years ago, at which time a major subduction earthquake caused subsidence of this portion of the coast and rapid cliff recession. The longshore variations in beach sand grain sizes and accompanying beach morphology are playing an important role in the continuing sea cliff erosion with cliffs backing the coarse-grained reflective beaches eroding more rapidly than the cliffs buffered by the fine-grained dissipative beaches.

Shulmeister, J., and R.M. Kirk, Holocene fluvial-coastal interactions on a mixed sand and sand and gravel beach system, North Canterbury, New Zealand, Catena, 30 (4), 337-355, 1997.

Fluvio-coastal interactions are examined on a progradational sand, and mixed sand and gravel beach sequence between the Ashley and Kowai rivers, Pegasus Bay, New Zealand. This coastal system presents an example of a wave-dominated environment energetic enough to deal with the sediment supply derived from the rivers, but where the coast is still prograding. Progradation occurs because of the inability of the marine system to evacuate wave-eroded sediment from the bay floor. This results in gradual nearshore aggradation until nearshore storage is filled and sediment is finally transported landward to form a new beach ridge. This type of coastal system can be identified by a diagnostic morphological assemblage comprising a 'small river' coastal morphology (sensu Zenkovich (1967, Processes of Coastal Development, Oliver and Boyd, Edinburgh) backed by a sequence of beach ridges. Sediment fractionation (shape and size sorting) is identified as the primary effect of erosional processes on a mixed sand and gravel beach. Fractionation is capable of converting sandy beaches with minor gravel components to gravel-dominated beaches. Gravel is concentrated by the evacuation of sand from the shoreface. This occurs dominantly through storm sifting but also occurs in response to normal swash processes. This process is very similar to the process of chenier production on mixed mud and sand beaches, and fractionation is highlighted as a dominant erosional process on mixed beaches, irrespective of grain size. (C) 1997 Elsevier Science B.V.

Skotner, C., I.G. Jonsson, and J. Skourup, Wave-Forces On a Large, Horizontal Submerged Cylinder, Ocean Engineering, 21 (8), 711-731, 1994.

A numerical boundary integral equation method combined with a non-linear time stepping procedure is used for the calculation of wave forces on a large, submerged, horizontal circular cylinder. As the method is based on potential theory, all computations are performed in the inertia dominated domain, that is, for small Keulegan-Carpenter numbers. Computations are carried out for the Eulerian mean current under wave trough level equal to zero. When the cylinder is moved towards the sea bed the computations show that the inertia coefficients increase significantly, which is associated with a blockage effect. Furthermore, the effect of the wave steepness is reduced when the submergence of the cylinder is increased. In the vicinity of the free water surface the vertical inertia coefficient is highly dependent upon the wave steepness, which tends to reduce it, whereas the horizontal inertia coefficient is only slightly dependent on the wave steepness. Computations are also carried out for cylinder diameters comparable with the wave length. Finally, inertia coefficients computed by the present method are compared with some analytical results by Ogilvie [(1963), First and second order forces on a cylinder submerged under a free surface. J. Fluid Mech. 16, 451-472]. As long as the assumptions leading to Ogilvie's theory are fulfilled (cylinder radius small compared to the wave length), the results are quite similar.

Skotner, C., and C.J. Apelt, Application of a Boussinesq model for the computation of breaking waves Part 1: Development and verification, Ocean Engineering, 26 (10), 905-925, 1999.

Based on a set of Boussinesq-type equations with improved linear frequency dispersion characteristics in deeper water, the present paper incorporates the simplified effect of spilling wave breaking into the equations. The analysis is restricted to a single horizontal dimension but the method can be extended to include the second horizontal dimension. Inside the surf zone the vertical variation of the horizontal velocity profile is assumed to be composed of an (initially unknown) organised velocity component below the roller and a surface roller travelling with the wave celerity. This leads to a new set of equations which is capable of simulating the transformation of waves before, during and after wave breaking. The model is calibrated and verified by comparison with several wave flume measurements. The results show that the model produces sound physical results. (C) 1999 Elsevier Science Ltd. All rights reserved.

Skourup, J., and I.G. Jonsson, Computations of Forces On, and Particle Orbits Around, Horizontal Cylinders Under Steep Waves, Ocean Engineering, 19 (6), 527-553, 1992.

A numerical method, based on a boundary integral equation combined with a nonlinear time stepping procedure for the free water surface, is developed for simulations of the interaction between highly non-linear water waves and submerged horizontal cylinders. The method is based on potential theory, and the omission of viscous effects restricts the wave-structure interaction computations to low Keulegan-Carpenter numbers where inertia forces are dominant. The numerical scheme is verified by computations with a steep wave of exact form during several wave periods, and by computations of a breaking wave. A new method for tracing the orbits of water particles in the fluid domain is developed, and the influence from submerged structures on the orbits is visualized through several computational examples. The wave forces on submerged structures are computed and are found to correspond well with other computed results for low Keulegan-Carpenter numbers.

Skovgaard, O., I.G. Jonsson, and J.A. Bertelsen, Computation of Wave Heights Due to Refraction and Friction, Journal of the Waterways Harbors and Coastal Engineering Division-Asce, 101 (WW1), 15-32, 1975.


Skovgaard, O., I.G. Jonsson, and J.A. Bertelsen, Computation of Wave Heights Due to Refraction and Friction - Closure, Journal of the Waterways Harbors and Coastal Engineering Division-Asce, 102 (1), 100-105, 1976.


Skovgaard, O., and I.G. Jonsson, Solution of a Water Wave-Equation For an Inhomogeneous-Medium, Zeitschrift Fur Angewandte Mathematik Und Mechanik, 58 (7), T328-T331, 1978.


Skovgaard, O., and I.G. Jonsson, Computation of Wave Fields in the Ocean Around an Island, International Journal For Numerical Methods in Fluids, 1 (3), 237-272, 1981.


Soares, A.G., A. McLachlan, and T.A. Schlacher, Disturbance effects of stranded kelp on populations of the sandy beach bivalve Donax serra (Roding), Journal of Experimental Marine Biology and Ecology, 205 (1-2), 165-186, 1996.

Twelve beaches on the coast west of Cape Agulhas, South Africa, were surveyed to examine the influence of several physical factors, including stranded kelp, on the zonation, density and biomass of populations of the wedge clam Donax serra. Biomass and density of adult clams were significantly higher on beaches with lower cover of stranded kelp; this pattern did not hold for juveniles. Discriminant analysis of beaches with and without Donax classified these beaches 100% correctly - the most important factor being kelp cover followed by average winter temperature, wave height, morphodynamic state, beach length, wave period and beach slope. Beaches with Donax had a significantly lower percentage of the drift line covered by stranded kelp (mean = 30%) than beaches without Donax (mean = 77%). On two beaches of the southwest coast with similar morphodynamics and temperature regimes but different kelp cover, adult populations were centered in different zones: in the low intertidal to subtidal where kelp cover was higher (mean = 42%) and in the mid-intertidal where no kelp was found. A disturbance hypothesis is developed to explain the observed patterns: kelp stranding in varying quantities interferes with Donax feeding and burrowing activities, dislodging animals of increasing size gradually downshore to the saturation and inner surf zones, where adult populations are eventually established. In the presence of extremely high quantities of stranded kelp, both juveniles and adults would be dislodged from the intertidal to the subtidal. The disturbance process may interact with several other physical factors, being magnified when coupled with low temperatures and small waves on reflective pocket beaches with steep slopes and coarse sands. Additionally, kelp gulls predate dislodged animals, explaining the absence of clams in a stretch of 20 m above the swash zone. It is thus concluded that the zonation patterns here observed are the result of a disturbance effect triggered by stranded kelp and mediated by multiple interacting factors. The adaptations of Donax serra that enable it successfully to colonize intertidal and subtidal habitats of the beach ecosystem are discussed.

Soons, J.M., J. Shulmeister, and S. Holt, The Holocene evolution of a well nourished gravelly barrier and lagoon complex, Kaitorete ''Spit'', Canterbury, New Zealand, Marine Geology, 138 (1-2), 69-90, 1997.

Morphological, stratigraphical, micropaleontological and radiocarbon dating investigations of the gravelly Kaitorete ''Spit'' system, Canterbury, New Zealand show that a barrier/spit system has existed at this site for the last 8000 yr. Kaitorete ''Spit'' developed as a true spit extending north from near the Rakaia river mouth, during sea level rise in the Late Pleistocene and Early Holocene. This produced an estuarine coastline along the southwestern flank of Banks Peninsula. The spit extended to Banks Peninsula sometime in the early mid- Holocene creating a barrier lake complex behind the spit. Since the mid-Holocene, there have been at least three fluctuations between lacustrine and estuarine/lagoona1 conditions in the barrier blocked system. The most recent fluctuation, which resulted in the present barrier lake complex, occurred within the last 200-500 yr. These fluctuations are associated with the avulsion of a large braided river, the Waimakariri, to and from the Lake Ellesmere basin. When the river flows through the basin, a permanent channel is maintained to the ocean with estuarine conditions present. When the river flows elsewhere, the barrier closes and a freshwater lake system forms behind it. This study emphasises the importance of fluvial control on the evolution of gravelly coastlines where sediment supply is not the limiting factor. Both the sediments and the water in the back barrier area are predominantly derived from the terrestrial catchment. We highlight the absence of true marine influence in the back barrier area, except in the vicinity of the tidal channel, even when such a channel is present. Marine processes have been limited to the gradual re-orientation of the barrier system from drift to swash alignment. (C) 1997 Elsevier Science B.V.

Sorensen, O.R., H.A. Schaffer, and P.A. Madsen, Surf zone dynamics simulated by a Boussinesq type model. III. Wave-induced horizontal nearshore circulations, Coastal Engineering, 33 (2-3), 155-176, 1998.

This is the third of three papers on the modelling of various types of surf zone phenomena by the use of a time-domain Boussinesq type model, which is extended to the surf zone and swash zone by including a simple description of wave breaking and a moving boundary at the shoreline. In the first paper [Madsen, P.A., Sorensen, O.R., Schaffer, H.A., 1997. Surf zone dynamics simulated by a Boussinesq type model: Part 1. Model description and cross-shore motion of regular waves. Coastal Eng. 32, 255-288.], the numerical model was described and it was applied to study cross-shore motion of regular waves in the surf zone including shoaling, breaking and runup. The first paper also included a discussion of time-averaged quantities derived from the time-domain solutions. The second paper [Madsen, P.A., Sorensen, O.R., Schaffer, H.A., 1997. Surf zone dynamics simulated by a Boussinesq type model: Part 2. Surf beat and swash oscillations for wave groups and irregular waves. Coastal Eng. 32, 289-320.] treated the cross-shore motion of wave groups and irregular waves with emphasis on the resulting shoreline motion and surf beat. The present paper concentrates on wave breaking and wave-induced currents in the horizontal plane. This is done without the traditional splitting of the phenomenon into a wave problem and a current problem. Mutual interaction between short waves and long waves and wave-induced (depth-averaged) currents is inherent in the model. Two situations are studied with waves normally incident on a plane sloping beach, but with some alongshore non- uniformity. In the first example, a rip channel is present and the other concerns a detached breakwater parallel to the shoreline. In both situations, wave-driven currents are generated and circulation cells appear. In turn, the currents appear to affect the waves. Results are presented for the case of unidirectional waves as well as for directionally spread waves. The resulting current patterns and wave height distributions are shown to be in good agreement with laboratory measurements from the literature. (C) 1998 Elsevier Science B.V.

Staub, C., I.G. Jonsson, and I.A. Svendsen, Sediment suspension in oscillatory flow: Measurements of instantaneous concentration at high shear, Coastal Engineering, 27 (1-2), 67-96, 1996.

Different syphon type suspended load probes were used together with a specially developed ''carousel'' sampler for measurements of the instantaneous sediment concentration in turbulent oscillatory flow over a sand bed, Shields parameters were well above the ripple/flat bed transition region, resulting in intense sediment transport over a flat bed, The measurements were performed at different levels in a large oscillating water tunnel. They showed some characteristic features of the temporal concentration variation at fixed levels, including a pronounced effect of the orientation of the suction tube relative to the flow. The variation with height of the average concentration is reasonably well described assuming a constant turbulent diffusivity, and the magnitude of this can be predicted relatively well using simple turbulence arguments. Two empirical formulae for the extrapolated bed concentration are also presented. The analysis is partly based on Wilson's finding that in sheet flow the equivalent bed roughness is nearly proportional with the Shields parameter, resulting in a roughness/grain diameter ratio much larger than 2.5, the figure often adopted for a flat bed, but without sheet flow.

Synolakis, C.E., M.K. Deb, and J.E. Skjelbreia, The Anomalous Behavior of the Runup of Cnoidal Waves, Physics of Fluids, 31 (1), 3-5, 1988.


Tanner, W.F., Origin of beach ridges and swales, Marine Geology, 129 (1-2), 149-161, 1995.

Sandy beach ridges occur in four main categories: (1) Swash- built, (2) Settling lag, (3) Eolian, (4) Storm surge. Ridges in the first two classes are geometrically regular, only a few tens of centimeters above adjacent swales, and commonly in ridge sets and systems (tens to hundreds of ridges each). Individual sets (of 5-25 ridges) tend to stand 0.5 m to 2 m above (or below) adjacent sets. Ridges in the third and fourth classes de, not have these characteristics, do not occur in sets, and are generally not suitable for detailed historical studies. No one of these ridges is the same as the storm-built berm, which is almost never preserved. Swash-built sandy beach ridges have diagnostic (1) map spacing, (2) accretion rate, (3) periodicity, (4) cross-bedding and (5) granulometry. The last two indicate fair-weather waves on a sandy beach, in contrast with settling-lag ridges (Postma style), which have the same external geometry but which were deposited without important wave work; and in contrast with storm-built berms, generally seen on eroding coasts, but rarely or never in beach ridge plains. The grain-size kurtosis of beach sand is an excellent index to near-shore wave energy density. Changes in kurtosis at ridge set boundaries mark changes in long-term wave energy density, hence in sea level. The latter can be deduced also from set height differences and from spacing differences. Periodicity is typically 30-60 years, map spacing 25-50 m and accretion rate fairly close to 1 m/yr. A few ridge sets, with intervals of 3-7, 10-12, or 18-19 years, have smaller spacings. This is not what can be done, if each ridge is built by one storm. If each ridge had been built by one storm, wide beach ridge plains (like one in Denmark, dating from about 11,700 yr B.P.), would have been formed in the last 30-50 years, at accretion rates of hundreds of meters per year. Instead, each swash-type sandy beach ridge was made by a sea-level rise-and- fall couplet (amplitude, 5-30 cm). The swale marks the lower position. This mechanism reflects the fact that the transverse profile, from beach to sea, is gently concave upward, with maximum curvature close to shore; this is a shape which is out of adjustment with the shoaling wave system shortly after a small sea-level change. Settling-lag ridges were built without waves, hence the ridge-and-swale sequence in this case cannot be attributed to waves, either fair-weather or storm. These ridges show the same historical pattern as do swash-built ridges; this fact suggests that both were controlled by the same mechanism (sea-level change).

Taylor, M., and G.W. Stone, Beach-ridges: A review, Journal of Coastal Research, 12 (3), 612-621, 1996.

A review of the beach-ridge literature is provided with emphasis on those composed of sand. Although confusion in the literature exists on differentiating beach-ridges from cheniers, both are viewed here as morphogenetically distinct. Several models describing the evolution of beach-ridges in diverse coastal settings have been published. Review of these models indicates that beach-ridges are deposited by swash during high or low wave-energy conditions, and may also emerge through aggradation of an offshore bar. Additionally, numerous models emphasize the role of vegetation and aeolian deposition in the stabilization, accretion, and preservation of beach- ridges. Beach-ridges generally prograde when an abundance of sediment exists and the offshore gradient is low. Sea-level changes do not determine beach-ridge growth, but can affect the orientation and elevation of beach-ridge sets in a beach-ridge plain. Interruption, truncation, erosion of beach-ridges, and deposition of younger beach-ridges with a different orientation and shape may be caused by climate, sea-level, or sediment supply fluctuations. Thus beach-ridges are utilized in the reconstruction of sea-level, climate, and sediment budget histories. Growth rates of beach-ridges are studied in an attempt to elucidate rates of coastal progradation. Absolute quantification of beach-ridge growth rates is limited by the scarcity of reliable in situ material for dating. Growth rates can also be erroneous due to erosion of some beach-ridges making up a beach-ridge plain. The study of beach-ridges has progressed from descriptions of their morphology and discussions on beach-ridge origin, to the use of these landforms in the interpretation of paleo-environments.

Tchamen, G.W., and R.A. Kahawita, Modelling wetting and drying effects over complex topography, Hydrological Processes, 12 (8), 1151-1182, 1998.

The numerical simulation of free surface flows that alternately flood and dry out over complex topography is a formidable task. The model equation set generally used for this purpose is the two-dimensional (2D) shallow water wave model (SWWM). Simplified forms of this system such as the zero inertia model (ZIM) can accommodate specific situations like slowly evolving floods over gentle slopes. Classical numerical techniques, such as finite differences (FD) and finite elements (FE), have been used for their integration over the last 20-30 years. Most of these schemes experience some kind of instability and usually fail when some particular domain under specific flow conditions is treated. The numerical instability generally manifests itself in the form of an unphysical negative depth that subsequently causes a run-time error at the computation of the celerity and/or the friction slope. The origins of this behaviour are diverse and may be generally attributed to: 1. The use of a scheme that is inappropriate for such complex flow conditions (mixed regimes). 2. Improper treatment of a friction source term or a large local curvature in topography. 3. Mishandling of a cell that is partially wet/dry. In this paper, a tentative attempt has been made to gain a better understanding of the genesis of the instabilities, their implications and the limits to the proposed solutions. Frequently, the enforcement of robustness is made at the expense of accuracy. The need for a positive scheme, that is, a scheme that always predicts positive demand when run within the constraints of some practical stability limits, is fundamental. It is shown here how a carefully chosen scheme (in this case, an adaptation of the solver to the SWWM) can preserve positive values of water depth under both explicit and implicit time integration, high velocities and complex topography that may include dry areas. However, the treatment of the source terms: friction, Coriolis and particularly the bathymetry, are also of prime importance and must not be overlooked. Linearization with a combination of switching between explicit-implicit integration can overcome the 'stiffness' of the friction and Coriolis terms and provide stable numerical integration. The treatment of the bathymetry source term is much mon delicate. For cells undergoing a transient wet-dry process, the imposition of zero velocity stabilizes most of the approximations, However, this artificial zero velocity condition can be the cause of considerable error, especially when fast moving fronts are involved. Besides these difficulties linked with the internal position of the front within a cell versus the limited resolution of a numerical grid, it appears that the second derivative that defines whether the bed is locally convex or concave is a key indicator for stability. A convex bottom may lead to unbounded solutions. It appears that this behaviour is not linked to the numerics (numerical scheme) but rather to the mathematical theory of the SWWM. These concerns about stability have taken precedence, until now, over the crucial and related question of accuracy, especially near a moving front, and how these possible inaccuracies at the leading edge may affect the solution at interior points within the domain. This paper presents an in depth, fully two-dimensional space analysis of the aforementioned problem that has not been addressed before. The purpose of the present communication is not to propose what could be viewed as a `final solution', but rather to provide some key considerations that may reveal the ingredients and insight necessary for the development of accurate and robust solutions in the future. (C) 1998 John Wiley & Sons. Ltd.

Thompson, T.A., and S.J. Baedke, Strand-plain evidence for late Holocene lake-level variations in Lake Michigan, Geological Society of America Bulletin, 109 (6), 666-682, 1997.

Lake level is a primary control on shoreline behavior in Lake Michigan. The historical record from lake-level gauges is the most accurate source of information on past lake levels, but the short duration of the record does not permit the recognition of long-term patterns of lake-level change (longer than a decade or two). To extend the record of lake-level change, the internal architecture and timing of development of five strand plains of late Holocene beach ridges along the Lake Michigan coastline were studied. Relative lake-level curves for each site were constructed by determining the elevation of foreshore (swash zone) sediments in the beach ridges and by dating basal wetland sediments in the swales between ridges. These curves detect long-term (30+ yr) lake-level variations and differential isostatic adjustments over the past 4700 yr at a greater resolution than achieved by other studies. The average timing of beach-ridge development for all sites is between 29 and 38 yr/ridge. This correspondence occurs in spite of the embayments containing the strand plains being different in size, orientation, hydrographic regime, and available sediment type and caliber. If not coincidental, all sites responded to a lake-level fluctuation of a little more than three decades in duration and a range of 0.5 to 0.6 m. Most pronounced in the relative lake-level curves is a fluctuation of 120-180 yr in duration. This approximate to 150 yr variation is defined by groups of four to six ridges that show a rise and fall in foreshore elevations of 0.5 to 1.5 m within the group. The 150 yr variation can be correlated between sites in the Lake Michigan basin. The approximate to 30 and 150 yr fluctuations are superimposed on a long-term loss of water to the Lake Michigan basin and differential rates of isostatic adjustment.

Ting, F.C.K., and J.T. Kirby, Dynamics of Surf-Zone Turbulence in a Strong Plunging Breaker, Coastal Engineering, 24 (3-4), 177-204, 1995.

The characteristics of turbulence created by a plunging breaker on a 1 on 35 plane slope have been studied experimentally in a two-dimensional wave tank. The experiments involved detailed measurements of fluid velocities below trough level and water surface elevations in the surf zone using a fibreoptic laser- Doppler anemometer and a capacitance wave gage. The dynamical role of turbulence is examined making use of the transport equation for turbulent kinetic energy (the k-equation). The results show that turbulence under a plunging breaker is dominated by large-scale motions and has certain unique features that are associated with its wave condition. It was found that the nature of turbulence transport in the inner surf zone depends on a particular wave condition and it is not similar for different types of breakers. Turbulent kinetic energy is transported landward under a plunging breaker and dissipated within one wave cycle. This is different from spilling breakers where turbulent kinetic energy is transported seaward and the dissipation rate is much slower. The analysis of the k-equation shows that advective and diffusive transport of turbulence play a major role in the distribution of turbulence under a plunging breaker, while production and dissipation are not in local equilibrium but are of the same order of magnitude. Based on certain approximate analytical approaches and experimental measurements it is shown that turbulence production and viscous dissipation below trough level amount to only a small portion of the wave energy loss caused by wave breaking. It is suggested that the onshore sediment transport produced by swell waves may be tied in a direct way to the unique characteristics of turbulent flows in these waves.

Titov, V.V., and C.E. Synolakis, Modeling of Breaking and Nonbreaking Long-Wave Evolution and Runup Using Vtcs-2, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 121 (6), 308-316, 1995.

We present a variable grid finite-differences approximation of the characteristic form of the shallow-water-wave equations without artificial viscosity or friction factors to model the propagation and runup of one-dimensional long waves, referred to as VTCS-2. We apply our method in the calculation of the evolution of breaking and nonbreaking waves on sloping beaches. We compare the computational results with analytical solutions, other numerical computations and with laboratory data for breaking and nonbreaking solitary waves. We find that the model describes the evolution and runup of nonbreaking waves very well, even when using a very small number of grid points per wavelength. Even though our method does not model the detailed surface profile of wave breaking well, it adequately predicts the runup of plunging solitary waves without ad-hoc assumptions about viscosity and friction. This appears to be a further manifestation of the well-documented but unexplained ability of the shallow water wave equations to provide quantitatively correct runup results even in parameter ranges where the underlying assumptions of the governing equations are violated.

Titov, V.V., and C.E. Synolakis, Extreme inundation flows during the Hokkaido-Nansei-Oki tsunami, Geophysical Research Letters, 24 (11), 1315-1318, 1997.

The tsunami generated by the July 12, 1993 Hokkaido-Nansei-Oki M-w = 7.8 earthquake produced in Japan the worst local tsunami- related death toll in fifty years, with estimated 10-18m/sec overland flow velocities and 30m runup. These extreme values are the largest recorded in Japan this century and are among the highest ever documented for non-landslide generated tsunamis. We model this event to confirm the estimated overland flow velocities, and we find that, given reasonable ground deformation data, current state-of-the-art shallow-water wave models can predict tsunami inundation correctly including extreme runup, current velocities and overland flow. We find that even small local topographic structures affect the runup to first-order, and that the resolution of the bathymetric data is more important than the grid resolution. Our results qualitatively suggest that for this event-coastal inundation is more correlated with inundation velocities than with inundation heights, explaining also why threshold-type modeling has substantially underpredicted coastal inundation for this and other recent events.

Titov, V.V., and C.E. Synolakis, Numerical modeling of tidal wave runup, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 124 (4), 157-171, 1998.

A numerical solution for the 2 + 1 (long-shore and onshore propagation directions and time) nonlinear shallow-water wave equations, without friction factors or artificial viscosity is presented. The models use a splitting method to generate two 1 + 1 propagation problems, one in the onshore and the other in longshore direction. Both are solved in characteristic form using the method of characteristics. A shoreline algorithm is implemented, which is the generalization of the earlier 1 + 1 algorithm used in the code VTCS-2. The model is validated using large-scale laboratory data from solitary wave experiments attacking a conical island. The method is applied then to model the 1993 Okushiri, Japan, the 1994 Kuril Island, Russia, and the 1996 Chimbote, Peru tsunamis. It is found that the model can reproduce correctly overland flow and even extreme events such as the 30-m runup and the 20-m/s inundation velocities inferred during field surveys. The results suggest that bathymetric and topographic resolution of at least 150 m is necessary for adequate predictions, while at least 50 m resolution is needed to model extreme events, contrary to intuitive expectations that long waves would not interact with morphological features of such short scales.

Trenhaile, A.S., L.V. VanDerNol, and P.D. LaValle, Sand grain roundness and transport in the swash zone, Journal of Coastal Research, 12 (4), 1017-1023, 1996.

This study considered the effect of particle roundness on the movement of sand grains in the swash zone. A wave tank was used to investigate the transport of a sample of quartz grains of fairly uniform size up an inclined ramp. A similar procedure, using fluorescently dyed grains, was used in the field in southern Lake St. Clair, Ontario. It was found that rounder grains were preferentially transported towards the upper part of the swash zone in the laboratory and field. Round grains may congregate on the berm and upper foreshore because of their higher settling velocities or their greater ease of entrainment compared with more angular grains.

Tsai, C.P., J.S. Wang, and C. Lin, Downrush flow from waves on sloping seawalls, Ocean Engineering, 25 (4-5), 295-308, 1998.

This paper investigates the characteristics of downrush flow from breaking waves on sloping seawalls, which cause toe scour. Flow visualization techniques were employed in these experiments. The velocity and pressure of the downrush flow at the toe were analyzed. It was found that the intensity of the flow is reduced as the structure slope decreases. The empirical formula for normalized flow intensity at the structure toe is presented as a function of the relative wave run-up height. (C) 1997 Elsevier Science Ltd.

Turner, I.L., Modelling the time-varying extent of groundwater seepage on tidal beaches, Earth Surface Processes and Landforms, 20 (9), 833-843, 1995.

The outcrop of groundwater on tidal beaches distinguishes an upper unsaturated region from a lower saturated region of the intertidal profile. Since the 1940s, it has been recognized that the extent of groundwater seepage at the beach face is one factor determining the tendency for erosive or accretionary conditions to prevail. As a primary step towards incorporating bed saturation characteristics within cross-shore sediment transport models, this paper (and accompanying program disk) details a simple model to simulate the time-varying extent of seepage face development across tidal beaches. From a comparison with field results obtained on the macrotidal Central Queensland (Australia) coast, the model appears to provide an encouraging degree of predictive capability. The model also assists in highlighting the sensitivity of seepage face development to varying beach face, tide and wave characteristics.

Turner, I.L., Simulating the Influence of Groundwater Seepage On Sediment Transported By the Sweep of the Swash Zone Across Macro-Tidal Beaches, Marine Geology, 125 (1-2), 153-174, 1995.

A numerical model is developed to simulate the influence of groundwater seepage on swash zone sediment transport across macro-tidal beaches. The emergence of equilibrium profile morphology is examined in response to varying tide, sediment and initial profile characteristics. Due to the unresolved complexities of boundary layer flow and corresponding shear stresses in the swash zone, sediment transport across the beach face is modelled by incorporating an uprush phase described by the shallow water wave equations, within an heuristic model of equilibrium beach face slope. A new parameter, termed the ''M'' net transport parameter, is defined to parameterize the net flux of sediment per uprush-backrush cycle. The definition of differing equilibrium gradients across saturated versus unsaturated regions of the intertidal profile permits the saturation characteristics of the bed to be incorporated. The dynamics of the watertable exit point on the beach face is central to the scheme, as this defines the time-varying extent of saturated and unsaturated regions of the intertidal profile. The sensitivity of coastal seepage face development to tide, profile and sediment characteristics is highlighted through the derivation of a new seepage face parameter. The simulation model is found to successfully reproduce key aspects of observed profile adjustment and resulting equilibrium morphology. Complex morphodynamic feedback is observed between: the tidal stage, net transport per uprush-backrush cycle, profile slope, and the dynamics of the watertable outcrop. Net upper-profile steepening and lower-profile lowering is simulated on beaches composed of medium to coarse sand. This results in the emergence of a distinctive break in slope within the intertidal profile. Such morphology is commonly observed on macro-tidal coasts.

Turner, I.L., and P. Nielsen, Rapid water table fluctuations within the beach face: Implications for swash zone sediment mobility?, Coastal Engineering, 32 (1), 45-59, 1997.

To incorporate groundwater infiltration/exfiltration in the description of swash zone sediment transport, it is required that the details of groundwater dynamics within the beach face be clarified. Field measurements of the vertical pore-pressure structure within the bed identify capillarity effects as the primary mechanism driving rapid and relatively large magnitude water table fluctuations within the swash zone. When the upper extent of the fully saturated capillary fringe coincides with the beach face surface, wave runup produces near-instantaneous increase in pore-pressures across the capillary fringe, corresponding to a rapid rise of the phreatic surface (i.e. the surface where pore-pressure = atmospheric pressure) to the sand surface. Therefore, counter to previous conclusions in the literature, the rapid rise and fall of the water table under the swash zone do not equate to regions of the beach face alternating between states that favor sediment deposition (unsaturated) and erosion (saturated). Similar reports that rapid fluctuations of the water table within the beach face correspond to rapid rates of vertical now and hence bed fluidization, are also a misinterpretation. Field measurements, and a careful consideration of saturation and pore-pressure characteristics within the beach face, demonstrate that rapid water table rise is associated with minute (downwards) swash infiltration, rather than rapid (upwards) groundwater exfiltration. The cause of the pressure fluctuations and phreatic surface oscillations is the alternating appearance and disappearance of meniscuses at the sand surface, which generate pressure head fluctuations of decimeters due to the addition of millimeters of water. (C) 1997 Elsevier Science B.V.

Turner, I.L., and S.P. Leatherman, Beach dewatering as a 'soft' engineering solution to coastal erosion - A history and critical review, Journal of Coastal Research, 13 (4), 1050-1063, 1997.

For over half a century, researchers have reported a link between the elevation of beach groundwater and erosional or accretionary trends at the beach face. Beach dewatering (the artificial lowering of the watertable within beaches by a system of drains and pumps) is proposed by its proponents as a practical alternative to more traditional methods of shoreline stabilization. Within the last 15 years several test sites have been installed, and to date seven commercial dewatering systems have operated. This paper traces the origins and development of the dewatering concept, from early work on beach face permeability and beach groundwater dynamics, to recent field and laboratory studies that have explicitly examined the effect of artificial groundwater manipulation on beach face accretion and erosion. All test and commercial dewatering installations undertaken to date are detailed, and published monitoring results from the two longest-running sites are critically re- assessed. It is concluded that the effectiveness of the dewatering concept in maintaining beach stability and controlling coastal retreat is yet to be convincingly demonstrated at the prototype scale. Some ideas are discussed for further research that may shed light on the underlying physical mechanisms, and if warranted, provide the basis for future design criteria.

Turner, I.L., and G. Masselink, Swash infiltration-exfiltration and sediment transport, Journal of Geophysical Research-Oceans, 103 (C13), 30813-30824, 1998.

Field measurements of vertical pore-pressure gradients within the bed are used to quantify instantaneous (8 Hz) rates of swash infiltration-exfiltration across the beach face. Cyclic infiltration-exfiltration is associated with individual swash events, with observed vertical flow rates O(10(-3)) m/s. Rates of net swash-groundwater exchange (i.e., through-bed flow integrated over several swash cycles) are two orders of magnitude smaller. At the timescale of individual swashes, vertical pore-pressure gradients within the beach face are much greater than horizontal pore-pressure gradients. This permits application of the numerical solution of Darcy's law for one- dimensional vertical flow to model fluctuating pore pressures (and hence vertical through-bed flow). Vertical flow through a porous bed modifies sediment mobility in (at least) two ways: (1) Seepage forces change the effective weight of surficial sediments, and (2) boundary layer "thickening" or "thinning'' result in altered bed shear stresses. By considering these two (opposing) effects separately, a new Shields parameter is derived that incorporates terms for through-bed flow. Simulation of time-varying seepage force and bed stress effects over an uprush-backwash cycle suggests that the effect of altered bed stresses dominates over the change in effective weight and that infiltration-exfiltration effects are most important during uprush. Simulated transport rates are increased by up to 40% of the peak transport rate during uprush and reduced by 10% during backrush. In summary, swash infiltration-exfiltration across a saturated beach face enhances the net upslope transport of sediment.

Turner, I.L., Monitoring groundwater dynamics in the littoral zone at seasonal, storm, tide and swash frequencies, Coastal Engineering, 35 (1-2), 1-16, 1998.

Monitoring groundwater fluctuations and flow at the coast is of both practical and research interest to a range of coastal engineering applications. These include the operation of water supply and sewage waste disposal facilities in coastal dunes, foundation design for coastal structures, coastal flora and fauna impact studies, the investigation of sediment transport mechanisms at the foreshore, and coastline stability. An overview of instrumentation and deployment requirements is provided, making specific reference to techniques that have proven successful in coastal investigations. Groundwater monitoring is not a new science, but the application of these techniques to the littoral zone is enabling new measurements to be made. To assist coastal engineers and scientists in the planning and implementation of groundwater monitoring projects, five successful field deployments are described, and the data obtained illustrated. (C) 1998 Elsevier Science B.V. All rights reserved.

Van Heteren, S., D.M. Fitzgerald, P.A. McKinlay, and I.V. Buynevich, Radar facies of paraglacial barrier systems: coastal New England, USA, Sedimentology, 45 (1), 181-200, 1998.

Analysis of a large data base of ground-penetrating-radar (GPR) profiles from both natural and developed paraglacial barriers along the coast of New England has allowed identification of eight reflection configurations that characterize this type of mid- to high-latitude coastal environment. Bedrock anchor points yield primarily hyperbolic configurations, whereas glacial anchor points and sediment-source areas are characterized by chaotic, parallel, and tangential-oblique configurations. Beaches and dunes produce predominantly sigmoidal oblique, hummocky, reflection-free, and bounding- surface configurations. Back-barrier sediments may yield basin- fill configurations, but generally include abundant signal- attenuating units. The GPR data, calibrated with information from cores, were collected across swash-aligned and drift- aligned barriers in a variety of wave- and tidal-energy settings. Application of a 120-MHz antenna, as used in this study, enables portrayal of a range of sedimentary units, from individual bedforms (on single records) to entire barrier elements (using large numbers of intersecting GPR sections), at maximum vertical resolutions that vary between 0.2 m and 0.7 m. The most important drawback of GPR in the coastal environment is attenuation of the electromagnetic (EM) signal by layers of salt-marsh peat or by brackish or salty groundwater, primarily along barrier edges. This disadvantage is offset by many benefits. Data can be collected at rates of several km per day, making GPR an excellent reconnaissance tool. A core that is used in the calibration of GPR data can be matched with great accuracy to its position on the complementary GPR record, allowing detailed correlation between lithostratigraphy and reflection configuration.

VanDongeren, A.R., and I.A. Svendsen, Absorbing-generating boundary condition for shallow water models, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 123 (6), 303-313, 1997.

An absorbing-generating boundary condition is derived for the two-dimensional-horizontal nonlinear shallow equations using the method of characteristics. It assumes local superposition of the incoming and outgoing long waves at the boundary, and uses a relationship between the flux and surface elevation of the waves. This boundary condition allows the outgoing waves to leave the computational domain through the boundaries with a minimum of reflection, while specifying incoming waves at the same boundaries. The boundary condition's absorbing properties are tested for both linear and nonlinear waves for a range of amplitudes and of angles of incidence. Its performance is compared to the classical Sommerfeld radiation condition for the linear case and is shown to cause significantly less reflection errors, especially for oblique angles. Also, a case of simultaneous absorption and generation of waves at the same boundary is analyzed where it is shown that the errors are of the same order as for the case of absorption only. Finally the boundary condition is extended to include known currents.

Vangent, M.R.A., Wave Interaction With Berm Breakwaters, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 121 (5), 229-238, 1995.

Wave interaction with berm breakwaters is studied by means of a physical model and a numerical model. The physical-model tests have been used to verify the wave motion as calculated by the numerical model. The numerical model based on finite-amplitude shallow-water wave equations is capable of simulating the wave motion both on and inside the structure. This model for normally incident waves has been extended with a new morphological model for cross-structure transport, which resulted in a wave load-response model capable of simulating the reshaping process of the seaward slopes of dynamic coastal structures such as berm breakwaters and gravel beaches. The combined wave-morphological model has been verified with small- scale laboratory tests and with prototype data. Trends observed in physical model tests, such as the influence of wave height, wave period, and stone diameter on the reshaped seaward slopes, are also reproduced properly.

Veloso, V.G., and R.S. Cardoso, Population biology of the mole crab Emerita brasiliensis (Decapoda : Hippidae) at Fora Beach, Brazil, Journal of Crustacean Biology, 19 (1), 147-153, 1999.

The population biology of Emerita brasiliensis (Decapoda: Hippidae) was studied by means of bi-weekly sampling from October 1990 through March 1993 at Praia da Fora Beach, Rio de Janeiro, Brazil (22 degrees 57'S, 43 degrees 10'W). Two transects were established in the swash zone, and divided into 4 strata parallel to the waterline. From each stratum, 4 replicates were taken with a 0.04-m(2) sampler. Highest population densities were observed at the end of spring and during summer. The presence of ovigerous females and juveniles during the entire sampling period indicated continuous reproduction of the population. The sex ratio was 1.82 for males : 1.00 for females. Batch size varied from 610-1,093 eggs, for females 10-23 mm long, respectively. Growth and mortality rates were higher for females than for males. Longevity for 99% of the population varied approximately from 6-10 months.

Villeneuve, M., and S.B. Savage, Nonlinear, Dispersive, Shallow-Water Waves Developed By a Moving Bed, Journal of Hydraulic Research, 31 (2), 249-266, 1993.

Landslides and avalanches plunging into lakes or reservoirs located in mountainous regions can generate large waves which can result in loss of life and significant property damage. As is the case with tsunamis generated in the ocean by underwater seismic activity, landslide induced water waves result from the motion of a solid boundary of the fluid. The present study deals with the mathematical modelling of water waves developed in a channel by a moving bed. A set of depth-averaged governing equations is derived to predict the evolution of the free surface resulting from a predetermined bed motion. These equations, which constitute a generalization of the Boussinesq system for waves over a flat bed, include both nonlinear and dispersive effects. Numerical solutions are obtained by using the finite difference method coupled with a Flux Corrected Transport (FCT) algorithm. The resulting model is used to predict the waves resulting from simple bed motions.

Voropayev, S.I., J. Roney, D.L. Boyer, H.J.S. Fernando, and W.N. Houston, The motion of large bottom particles (cobbles) in a wave- induced oscillatory flow, Coastal Engineering, 34 (3-4), 197-219, 1998.

The purpose of this paper is to present the results of a series of experiments aimed at better understanding the dynamics of the motion of large bottom particles (cobbles) in a wave- induced oscillatory flow. This problem is closely related to the motion of cobbles along the bottom in an oscillatory flow such as occurs in coastal waters beyond the region of wave breaking. The aims of the study were (i) to mimic this process in laboratory experiments and (ii) to develop a physical model to predict cobble movements. The oscillatory flow was created in a long tank of rectangular cross-section using standing waves of large amplitude, objects of different shapes (spheres and disks) were placed in the flow and their subsequent motion along the tank floor was studied. The results of the observations were compared with the predictions of a theoretical model. For the range of parameters used in the experiments (shape, size, aspect ratio and density of cobbles, amplitude and frequency of the oscillatory flow and bottom friction), reasonable agreement between the measured and calculated values of the cobble displacements as a function of time was obtained. (C) 1998 Elsevier Science B.V. All rights reserved.

Voulgaris, G., D. Simmonds, D. Michel, H. Howa, M.B. Collins, and D.A. Huntley, Measuring and modelling sediment transport on a macrotidal ridge and runnel beach: An intercomparison, Journal of Coastal Research, 14 (1), 315-330, 1998.

Observations of hydrodynamics, fluorescent tracer dispersal and beach morphology were acquired in the intertidal zone of a macrotidal ridge and runnel beach. High frequency hydrodynamic data from pressure transducers and electromagnetic current meters were used to describe flow patterns in the intertidal zone while sediment transport rates were estimated using energetics and empirical models. Results from fluorescent tracer experiments provided information on net sediment movement over periods ranging from one to five tidal cycles whereas morphometric analysis was carried out to determine net beach movement during a period of 24 tidal cycles. Comparison of the results showed that sediment transport based on the hydrodynamic measurements did not agree with sediment movement derived using the tracer and morphometric methods. This disagreement is because the latter methods integrate processes occurring throughout the whole tidal cycle including those at very low water depths (swash zone processes). Hydrodynamic data were limited to periods of the tidal cycle where the mean water depth was greater than 0.5 m. Such limitation, imposed by the physical dimensions, principle of operation and installation procedures of the instruments is common in nearshore studies. Sediment transport results obtained by using hydrodynamic data obtained in macrotidal areas would be incomplete if swash-zone processes are not covered by the sampling scheme. However, comparison of results obtained for shorter periods (i.e. excluding shallow water) with those from other methods that integrate over the whole tidal cycle can be used to extract information on sedimentary processes for periods where no direct data are available.

Wallerstein, G., and S. Elgar, Shock-Waves in Stellar Atmospheres and Breaking Waves On an Ocean Beach, Science, 256 (5063), 1531-1536, 1992.

The phenomenon of ocean waves breaking on a beach is analogous to shock waves in the atmosphere of a pulsating star. In both cases a velocity discontinuity is clearly present. In stars the upper, expanding layer halts and falls back so as to interact with the rising gas at a shock. Similarly, a bore on a beach reaches its maximum extension before sliding back onto the next incoming wave. Analogous quantities such as the surface gravity of the star and the beach gradient in the ocean have similar effects on the flows and the nature of the discontinuity between them. Phenomena that are not analogous include the thermodynamic properties of the two media. Ocean observations may help solve some problems in shock phenomena associated with stellar pulsation.

Walton, T.L., Ocean City, Maryland, Wave Runup Study, Journal of Coastal Research, 9 (1), 1-10, 1993.

An investigation of wave runup using video camera technology at Ocean City, Maryland, is discussed. Past studies on wave runup statistics are reviewed and practical problems of the ave runup prediction problem are noted. Results are provided from a subset of the runup experiment and differences between wave runup level probability density functions and wave runup amplitude probability density functions are detailed.

Walton, T.L., A Tale of 2 Wave-Trains, Ocean Engineering, 22 (5), 457-488, 1995.

The present study is an investigation into the transfer of the wave energy as it propagates through the surf zone and the consequent evolution of the wave trains and the corresponding envelope of the wave trains. The generation of long wave energy is investigated and one approach to developing the nonlinear transfer function for the transformation process is attempted. A nondimensionalized format for expressing the data is suggested for clarifying future studies of this type.

Wang, P., R.A. Davis, and N.C. Kraus, Cross-shore distribution of sediment texture under breaking waves along low-wave-energy coasts, Journal of Sedimentary Research, 68 (3), 497-506, 1998.

Sediment samples were collected with streamer traps at different elevations in the water column and across the surf zone. Beach profiles and breaking waves were measured together with the sediment sampling. The experiments were conducted on beaches with various sediment composition ranging from well- sorted fine sand to poorly sorted gravel and shell debris. The cross shore variation of sediment mean grain size ranged from less than 1 phi to significant variation of up to 3.5 phi. The resultant database contains 99 vertical grain-size profiles, composed of 99 bottom samples and 552 trap samples taken throughout the water column and at 29 different locations along the southeast coast of the United States and the Gulf coast of Florida. A homogeneous vertical profile of mean grain size and grain-size distribution pattern was found on most of the beaches with a wide range of sediment sizes, The homogeneous vertical profile, representing 92% of the measurements, was found on all morphological features: swash zone, breaker line, mid-surf zone, trough, and bar. A homogeneous distribution indicates that the vertical mixing mechanism in the water column of the surf zone is independent of sediment size ranging from fine sand to fine pebbles, Bottom sediment, represented by an 8-cm core sample, was generally coarser than the sediment trapped in the water column.

Wang, P., Longshore sediment flux in water column and across surf zone, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 124 (3), 108-117, 1998.

Streamer sediment traps were used to measure the distribution of longshore sediment flux in the surf zone at 29 locations along the southeast coast of the United States and the Gulf coast of Florida. Measurements were conducted on both barred and nonbarred coasts under low-wave energy conditions. Results indicate that longshore sediment flux decreases logarithmically upward in the water column throughout the surf zone, and the rate of upward decrease is largest in the trough and smallest in the swash due to stronger mixing energy in the swash. Six types of cross-shore distribution patterns of longshore sediment transport (LST) were found. These six distribution patterns are controlled by nearshore morphology, breaker type, and energy dissipation pattern. For low-wave energy coasts, the swash (nonbarred coast) and inner surf (barred coast) zones contain significant contributions to the longshore sediment transport rate. The cross-shore distribution pattern of the longshore sediment transport rate along nonbarred coasts was well reproduced using energy-dissipation and shear-stress approaches developed mainly from laboratory studies.

Williams, A.T., and G.T. Roberts, The measurement of pebble impacts and wave action on shore platforms and beaches: The swash force transducer (swashometer), Marine Geology, 129 (1-2), 137-143, 1995.

An instrument has been designed that can measure pebble impacts and wave forces in a harsh, high-energy, turbulent near-shore environment. The instrument weighs some 50 kg and stands 60 cm in height, and has a pebble sensor head that is interchangeable in that the size and shape can be representative of beach pebbles e.g. discoid, spherical, blade or rod like. Impacts on the sensor are recorded on a computer and the instrument can be programmed to run for varying time periods. Two characteristic force versus time traces, representing a different wave activity are presented. The instrument performed well throughout several tidal cycles and under a variety of energy conditions.

Wurjanto, A., and N. Kobayashi, Irregular Wave Reflection and Runup On Permeable Slopes, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 119 (5), 537-557, 1993.

A One-dimensional, time-dependent numerical model is developed to simulate the flow over a rough permeable slope as well as the flow inside a permeable underlayer of arbitrary thickness for specified normally incident irregular waves. The derivation of the one-dimensional continuity, momentum and energy equations employed in the numerical model is presented to clarify the basic assumptions made in these equations. The comparison of the numerical model with three test runs shows that the numerical model can predict the time series and spectral characteristics of the reflected waves and waterline oscillations on a 1:3 rough slope with a thick permeable underlayer. The computed results for the three runs indicate that the wave propagation, attenuation, and setup inside the permeable underlayer reduce the intensity of wave breaking and resulting energy dissipation on the slope but increase the energy influx and dissipation inside the thick permeable underlayer. Moreover, the permeability effects result in the time-averaged landward and seaward mass fluxes above and inside the permeable underlayer, respectively.

Yoshizawa, M., K. Shiga, N. Yoshimoto, N. Oki, H. Iwasaki, S. Kenmochi, and N. Kobayashi, Surface acoustic wave investigations of Y1-xPrxBa2Cu3Oy films, Physica B, 220, 179-181, 1996.

Temperature and magnetic field dependence of surface acoustic wave (SAW) velocity has been measured for Y1-xPrxBa2Cu3Oy films with x = 0.3 and x = 1. SAW velocity shows a step-like anomaly al the superconducting transition T-c, and a remarkable softening at low temperatures. The amount of the anomaly at T-c is 4.5 x 10(-5), which is the same order as bulk samples. SAW velocity below T-c is enhanced by applying the magnetic field, which is caused by interaction between the vortices and SAW.

You, Z.J., D.L. Wilkinson, and P. Nielsen, Velocity Distributions of Waves and Currents in the Combined Flow, Coastal Engineering, 15 (5-6), 525-543, 1991.

The theoretical model presented here is designed to predict waves and currents velocity profiles in the combined wave and current motion near a fixed bed. It is also valid for the pure wave motion, because the pure wave motion is only a special case of the combined flow. This model has been derived by using the equation of motion and the eddy viscosity assumptions which are somewhat different from those of former authors. Although the model is simple, the predictions are quite good compared with experimental data from Jonsson and Carlsen (1976) No. 1 and No. 2, Van Doorn (1981) V00RA, V10RA and V20RA, Van Doom (1982) S00RAL, S10RAL and S20RAL, and Jensen (1989) Test-12 and Test-13.

You, Z.J., D.L. Wilkinson, and P. Nielsen, Velocity Distribution in Turbulent Oscillatory Boundary-Layer, Coastal Engineering, 18 (1-2), 21-38, 1992.

The theoretical model presented here is designed to predict the velocity distribution in a turbulent oscillatory boundary layer over a fixed bed by using an eddy viscosity model. In this model. the appropriable nature of the eddy viscosity is discussed on the basis of experimental data. It is concluded that for a certain range of experimental conditions it is reasonable to assume that the eddy viscosity in the turbulent oscillatory boundary layer is a time independent and real- valued function of elevation only. Moreover, the present model has been compared with a wide range of experimental data and with the models of Kajiura (1968) and Myrhaug (1982). It has been found that the present model gives a better prediction on the velocity distribution than the former models.

You, Z.J., An Evaluation of Expressions For Wave Energy-Dissipation Due to Bottom Friction in the Presence of Currents - Comments, Coastal Engineering, 19 (3-4), 327-328, 1993.


You, Z.J., Eddy Viscosities and Velocities in Combined Wave Current Flows, Ocean Engineering, 21 (1), 81-97, 1994.

The eddy viscosities for the steady and the periodic components of combined wave-current flows have been studied quantitatively from the presently available experimental data. It has been found that inside the boundary interaction layer [z < delta] the eddy viscosity epsilon(c) for the steady flow is increased in the presence of waves while outside the boundary interaction layer [z > delta] it is affected little by the wave motion, and that the eddy viscosity c(w) for the wave motion in the boundary layer is independent of the current strength U*BAR. On the other hand, a new eddy viscosity model is presented to give a good prediction of the velocity distributions of the waves and currents in comparison with experimental data.

You, Z.J., Increase of current bottom shear stress due to waves, Coastal Engineering, 26 (3-4), 291-295, 1995.

The increase of current bottom shear stress in the presence of waves is studied. It is found that this increment is linearly proportional to the near-bed wave orbital velocity amplitude A omega and can be considered practically to be independent of the relative bed roughness k(s)/A and the angle theta between the wave propagation and the current. A new model is presented to calculate the current bottom shear stress in the presence of waves and gives better agreements with a wide range of presently available experimental data than Bijker's model.

You, Z.J., A Simple-Model For Current Velocity Profiles in Combined Wave- Current Flows - Reply, Coastal Engineering, 26 (1-2), 101-104, 1995.


You, Z.J., Bottom Friction Effects in the Combined Flow-Field of Random Waves and Currents - Comments, Coastal Engineering, 24 (3-4), 357-359, 1995.


You, Z.J., Transport of fine sands by currents and waves .2, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 122 (5), 265-266, 1996.


You, Z.J., The effect of wave-induced stress on current profiles, Ocean Engineering, 23 (7), 619-628, 1996.

Current velocity profiles in the presence of non-breaking waves on a horizontal bottom are studied. Particular consideration is given to the derivations of measured current profiles from the standard logarithmic profiles near the mean water surface. The deviations are found to be due mainly to the wave-induced second-order stress which was generally neglected in the former models. The available experimental data indicate that the wave- induced second-order stress is a linear function of elevation and depends on the wave parameters, the current strength and the angle between the waves and the current. A semi-empirical model is developed and gives good agreements with experimental measurements of current profiles near the mean water surface. Copyright (C) 1996 Elsevier Science Ltd

You, Z.J., Movable bed roughness and current profiles in the presence of irregular waves with an arbitrary angle to currents, Ocean Engineering, 23 (3), 225-242, 1996.

The bed roughness k(s) and current velocity profiles in the presence of waves with an arbitrary angle theta to currents are studied. It is found that the movable bed roughness is affected by both the wave and the current and only slightly by the angle theta between the wave propagation and the current, and that existing formulae derived in purely oscillatory flows generally fail to predict k(s). In the present study, a new formula which takes account the effect of the wave and the current on the bed roughness is suggested to calculate k(s) in combined wave- current flows. With the present formula, the current profiles calculated by the model of You agree satisfactorily with the laboratory data of van Kampen and Nap and Havinga, and the field measurements of Grant and Williams and Drake et al.

You, Z.J., On the vertical distribution of ((u)over-tilde-(w)over-tilde) by F.J. Rivero and A.S. Arcilla: Comments, Coastal Engineering, 30 (3-4), 305-310, 1997.


You, Z.J., Laboratory investigations into wave period effects on sand bed erodibility under the combined action of waves and currents, by G. Voulgaris et al: Comments, Coastal Engineering, 30 (1-2), 157-160, 1997.


You, Z.J., Initial motion of sediment in oscillatory flow, Journal of Waterway Port Coastal and Ocean Engineering-Asce, 124 (2), 68-72, 1998.

A new model is developed to study the initial motion of sediment in oscillatory flow over a flat bottom on the basis of available experimental data. It is found that the initial motion of sediment in oscillatory flow is uniquely defined by the simple model of A/d = KA(2) omega/v + B, where A = semiexcursion of wave orbital motion near the bed; omega = angular frequency; d = grain diameter; v = kinematic viscosity; and K and B = dimensionless coefficients determined by the immersed sediment weight. For a given sediment, the onset velocity derived from the model is found to initially increase with the wave period T and then approach a constant. A practical formula is also presented to calculate the onset velocity of sediment in the coastal zone.

You, Z.J., The inception of sheet flow in oscillatory flow, Ocean Engineering, 26 (3), 277-285, 1999.

A simple model is developed to study the inception of sheet flow in oscillatory flow based on the available experimental data. The inception of sheet flow in oscillatory flow is well defined by the simple model: A/d = KA(2)omega/nu + B, where A is the semi-excursion of wave orbital motion near the bed, d is the grain size, omega is the angular frequency, nu is the kinematic viscosity of water, and K and B are the coefficients and dependent on sediment properties only. The inception velocity of sheet flow derived from the model is shown to be the function of grain size d, oscillatory period T and specific sediment density s. For a given sediment, the inception velocity is found to increase sharply initially with T and then approach a constant at T > 6.0 s. The present model is quite simple and gives good agreement with the available experimental data. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

Zelt, J.A., The Run-Up of Nonbreaking and Breaking Solitary Waves, Coastal Engineering, 15 (3), 205-246, 1991.

The run-up of nonbreaking and breaking solitary waves on plane impermeable beaches is investigated with a Lagrangian finite- element Boussinesq wave model. Wave breaking is parameterized with an artificial viscosity (diffusion) term in the momentum equation, and bottom friction is modelled with a term quadratic in the horizontal fluid velocity. Comparisons are presented with laboratory data of maximum run-up, shoreline motion, and spatial profiles of near-shore free-surface elevation for both steep (20-degrees) and gradual (2.88-degrees) slopes. For the steep slope, only waves which do not break on run-up are considered, and excellent agreement is obtained with the laboratory data. For the gradual slope, wave shoaling, breaking, bore formation and subsequent collapse at the shoreline are predicted well by the model, although the breaking algorithm does not attempt to model the details of the turbulent flow in the breaking region. The backwash bore is also modelled reasonably well, although it persists longer in the numerical computations than in the laboratory data. It is shown that the inclusion of nonhydrostatic effects reduces the tendency of waves to break and improves the agreement of the numerical results with the laboratory run-up data. This allows higher amplitude waves to be modelled and larger propagation distances to be treated without the need to limit the wave steepness with artificial dissipation.