Abstract
When waves are incident to a sandy beach from two opposite directions, a cuspate foreland or a land-tied island may develop. A typical land-tied island can be seen offshore of Shodoshima Island in the Seto Inland Sea. Another example is Chiringashima Island located in the south part of Satsuma Peninsula, Kyushu. In both cases, the island and land are connected by an extremely slender sand bar that has been stably maintained for a long time, suggesting that it is stable against wave action from both sides of the sand bar. We developed a numerical model for predicting the elongation of a sand bar of a land-tied island using the BG model (a three-dimensional model for predicting beach changes based on Bagnold's concept).References
Nagayama, A., Yamaguchi, H., Chaya, A., Tanaka, R., Nakamura, K. and Asano, T. 2009. Study on emerging and submerging processes of a tombolo at Chiringashima Island, Ibusuki City, J. JSCE, Ser. B2 (Coastal Engineering), Vol. 65, No.1, pp. 586-590. (in Japanese)
Nagayama, A., Taniyama, M., Kawakami, K. and Asano, T. 2010. Study on deformation process of a tombolo throughout a whole year at Chiringashima Island, Ibusuki City, J. JSCE, Ser. B2 (Coastal Engineering), Vol. 66, No.1, pp. 156-160. (in Japanese)
Serizawa, M., Uda, T., San-nami, T. and Furuike, K. 2006. Three-dimensional model for predicting beach changes based on Bagnold's concept, Proc. 30th ICCE, pp. 3155-3167.
Serizawa, M., Miyahara, S. and Uda, T. 2014. Interaction between two circular sandy islands on flat shallow seabed owing to waves, Proc. 34th ICCE. (in press)
San-nami, T., Uda, T., Serizawa, M. and Miyahara, S. 2013. Prediction of devastation of natural coral cay by human activity, Proc. Coastal Dynamics 2013, Paper No. 138, pp. 1427-1438.