Influence of submarine topography change on current field due to sand mining has been investigated using numerical model experiment at off-Tadanoumi in the Seto Inland Sea. The calculated results show that the current field changes in not only the sand mining area but also the surrounding area. Furthermore, transportation mechanism of sand has been investigated to grope for the possibility of the sandbank recovery. As a result, it is suggested that there is a possibility that the sandbank will develop again from the Ookuno-Shima Island to the east in the far future, if the source of sand exists.
A huge amount of sea sand has been mined from many sandbanks in the Seto Inland Sea, because of uses for the construction material. On the other hand, the sandbank is an important place for the biological production. It is worried about the influence of the disappearance of the sandbank on the ecosystem at the sea. Furthermore, it is thought that the current field is affected due to the bottom topography change. The influence of the current field change on the water environment is also worried about. So, it is important to clarify the influence of the sand mining on the water environment. Off-Tadanoumi is one of the areas where the depth change is large in the Seto Inland Sea. Therefore, it is tried to clarify the influence on the current field by the topography change as a first step at off-Tadanoumi with use of the numerical model. Furthermore, it is tried to clarify the transportation mechanism of sea sand to grope for the possibility of the sandbank recovery using numerical model results.
Figure 1 shows the sand mining area at off-Tadanoumi. The hatched areas show areas in which the sand mining was permitted.