RELATIONSHIP BETWEEN SANDBANK TOPOGRAPHY AND TIDAL RESIDUAL FLOW IN THE SETO INLAND SEA

摘要

There are many sand banks in the Seto Inland Sea, Japan. These sand banks are generallyrnlocated behind islands or peninsulas. During high economic growth age, however, a hugernamount of sand was dredged from these sand banks in order to get an aggregate for concreternstructures such as highway roads or buildings. It is estimated that totally 600 million m3 ofrnsand was dredged from the Seto Inland Sea for last four decades. In this paper, the formationrnmechanisms of these sand banks and the environmental impacts due to change of topography arerninvestigated by physical model experiments and numerical model simulations. By the study,rnfollowing conclusions are obtained. (1) Sand banks are located around the center of tidalrnresidual circulation generated by islands or peninsulas. (2) The angle difference between therndirection of sand bank and the main direction of tidal current is about 15 to 30 degree. (3) Thernarea of sand banks is coincidence with the area of convergence of tidal residual flow on searnbottom layer.