2008 年 24 巻 p. 87-92
Numerical simulations of tsunami run-up have been carried out to investigate the effect of open gap in a coastal forest zone parallel to the shoreline. First, a straight open gap perpendicular to the shoreline is considered and the gap width is changed. As the gap width increases, the current velocity at the end of the open gap increases first, reaches to the maximum and then decreases, while the run-up height increases monotonously. The maximum velocity is 1.8 times comparing with the velocity without the coastal forest at the opening ratio of 0.075. This is mainly due to the effect of in-flow from the both sides of the open gap. Next, for the condition of the opening ratio with 0.075 the effects of an open gap parallel to the shoreline in the forest and a zigzag arrangement of the open gap are investigated. It is concluded that the effect of those difference in the arrangement is not large on the run-up height.