Ravindra Jayaratne, Yasufumi Takayama, Tomoya Shibayama


Study of beach morphological changes under storm conditions and its prediction capability are of paramount importance in coastal zone management. Seabed sediment is picked up violently in and outside the surf zone due to suspension mechanisms, therefore a considerable amount of sand is transported in coastal waters due to such mechanisms. For the construction of an accurate beach morphological model, it is necessary to elucidate the sediment suspension and to introduce it properly into the modelling of sediment transport. Jayaratne and Shibayama (2007) developed a complete set of explicit theoretical formulae to predict the time-averaged concentration on sandy beaches due to three suspension mechanisms: a) vortical motion over wave-generated sand ripples, b) from sheet flow, and c) turbulent motion under breaking waves. The present paper focuses on the development of a quasi-3D beach deformation model using the sediment concentration models of Jayaratne and Shibayama (2007), the bed load model of Watanabe (1982), the wave propagation model of Onaka et al. (1988), the nearshore current model of Philips (1977) and the undertow model of Okayasu et al. (1990) to predict the large-scale morphodynamics of sandy beaches. The predicted beach profiles and total sediment transport rates were compared with two sets of large-scale laboratory experimental data [Kajima et al. (1983); Kraus and Larson (1988)] and Seisho beach at Kanagawa Prefecture, Japan. It can be concluded that the present numerical model is capable of predicting sediment transport direction, on-offshore sand bar formation and the general trend of the beach profiles of large-scale erosive- and accretive-type sandy beaches to a satisfactory level.


large-scale beach morphological changes; sediment suspension; wave-generated sand ripples; sheet flow; breaking waves; sediment concentration; Quasi-3D beach deformation model

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Berkhoff, J.C.W. 1972. Computation of combined refraction-diffraction, Proceedings of 13th International Conference on Coastal Engineering, ASCE, 471-490.

Booij, N. 1981. Gravity waves on water with non-uniform depth and current, Communications on Hydraulics, No. 81-1, Department of Civil Engineering, Delft University of Technology, 131 pp.

Jayaratne, M.P.R., and T. Shibayama. 2007. Suspended sediment concentration on beaches under three different mechanisms, Coastal Engineering Journal, 49(4), 357-392.

Kajima, R., T. Shimuzu, K. Maruyama, and S. Saito. 1983. On-Offshore Sediment Transport Experiment by Using Large-Scale Wave Flume, Collected Data No. 1–8, Central Research Institute of Electrical Power Industry (CRIEPI), Japan (in Japanese).

Kirby, J.T. 1984. A note on linear surface wave-current interaction over slowly varying topography, Journal of Geophysical Research, 89(C1), 745-747.

Komar, P.D. 1977. Beach sand transport: Distribution and total drift, Proceedings of ASCE, 103, WW2, 225-239.

Kraus, N.C., and M. Larson. 1988. Beach Profile Change Measured in the Tank of Large Waves, 1956-1957 and 1962, Technical Report CERC-88-6, US Army Engineers Waterways Experiment Station.

Liu, P.L.F. 1983. Wave-current interaction on slowly varying topography, Journal of Geophysical Research, 88(C7), 4421-4426.

Ohnaka, S., A. Watanabe, and M. Isobe. 1988. Numerical modelling of wave deformation with a current, Proceedings of 21st International Conference on Coastal Engineering, ASCE, 393-407.

Okayasu, A., A. Watanabe, and M. Isobe. 1990. Modelling of energy transfer and undertow in the surf zone, Proceedings of 22nd International Conference on Coastal Engineering, ASCE, 123-135.

Phillips, O.M. 1977. The Dynamics of Upper Ocean, 2nd Edition, Cambridge University Press, London, 336 pp.

Rattanapitikon, W., and T. Shibayama. 1996. Cross-shore sediment transport and beach deformation model, Proceedings of 25th International Conference on Coastal Engineering, ASCE, 3062-3075.

Rattanapitikon, W., and T. Shibayama. 1998. Energy dissipation model for regular and irregular breaking waves, Coastal Engineering Journal, 40(4), 327-346.

Sato, S. 1987. Oscillatory Boundary Layer Flow and Sand Movement over Ripples, PhD Thesis, University of Tokyo, Japan.

Sato, S., K. Homma, and T. Shibayama. 1990. Laboratory study on sand suspension due breaking waves, Coastal Engineering in Japan, 33(2), 219-231.

Shibayama, T., and K. Horikawa. 1982. Sediment transport and beach transformation, Proceedings of 18th International Conference on Coastal Engineering, ASCE, 1439-1458.

Sunamura, T., and K. Horikawa. 1974. Two-dimensional beach transformation due to wave, Proceedings of 14th International Conference on Coastal Engineering, ASCE, 920-938.

Takayama, Y., T. Shibayama, and R. Jayaratne. 2012. A proposal of quasi-3D large-scale beach deformation model using local sand transport formula, Annual Journal of Coastal Engineering, JSCE, 68, 531-535 (in Japanese).

Van Rijn, L.C. 1984. Sediment transport, Part I: Bed load transport, Journal Waterways, Port, Coastal and Ocean Engineering, 110(10), 1431-1456.

Watanabe, A. 1982. Numerical models of nearshore currents and beach deformation, Coastal Engineering in Japan, 25, 147-161.

Watanabe, A., and K. Maruyama. 1986. Numerical modelling of nearshore wave field under combined refraction, diffraction and breaking, Coastal Engineering in Japan, 29, 19-39.

Watanabe, A., K. Maruyama, T. Shimizu, and T. Sakakiyama. 1986. Numerical prediction model of three-dimensional beach deformation around a structure. Coastal Engineering in Japan, 29, 179-194.