PREDICTION OF BEACH CHANGES AROUND ARTIFICIAL REEF USING BG MODEL

Hiroaki Fujiwara, Takaaki Uda, Toshiaki Onishi, Shiho Miyahara, Masumi Serizawa

Abstract


On the Kaike coast, one of the twelve detached breakwaters was converted into an artificial reef. After the conversion, the tombolo behind the structure was reduced in size because of the generation of shoreward currents on the artificial reef, and severe scouring occurred at the opening between the artificial reef and the existing detached breakwater owing to the development of rip currents. To investigate this, the BG model (a 3-D model for predicting beach changes based on Bagnold’s concept) proposed by Serizawa and Uda was improved to include the effect of not only waves but also strong nearshore currents. Also, the increase in the depth of closure due to currents was considered in the model. The predicted and measured beach changes around an artificial reef were in good agreement.

Keywords


artificial reef; detached breakwater; beach changes; rip currents; BG model; Kaike coast

References


Bagnold, R. A. 1963. Mechanics of marine sedimentation, in The Sea, Hill, M. N. (ed.), Vol. 3, Wiley, New York, 507-528.

Dally, W. R., R. G. Dean, and R. A. Dalrymple.1984. A model for breaker decay on beaches, Proc. 19th ICCE, 82-97.

Horikawa, K. ed. 1988. Nearshore Dynamics and Coastal Processes, University of Tokyo Press, Tokyo, 522 pp.

Larson, M., and N. C. Kraus. 1991. Numerical model of longshore current for bar and trough beaches, J. Waterway Port Coastal and Ocean Engineering, ASCE, Vol. 117, No. 4, 326-347.http://dx.doi.org/10.1061/(ASCE)0733-950X(1991)117:4(326)

Mase, H. 2001. Multidirectional random wave transformation model based on energy balance equation, Coastal Eng. J., JSCE, Vol. 43, No. 4, 317-337.

Serizawa, M., T. Uda, T. San-nami, K. Furuike, and T. Ishikawa. 2008. Model for predicting formation of dynamically stable ebb tidal delta off tidal inlet, Proc. 31st ICCE, 2291-2302.

Serizawa, M., and T. Uda. 2011. Prediction of formation of sand spit on coast with sudden change using improved BG model, Coastal Sediments '11, 1907-1919.


Full Text: PDF

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.