Basic study on the implementation of vegetation aimed at the reduction of tsunami damage

提出了沿海黑松树倒伏、连根、折断的判断图。提出了一种综合考虑倒伏、连根拔起和破坏条件的海岸森林海啸能量减少量估算方法(数值模拟法)。利用考虑树木相似规律制作的低矮海岸树木模型和高矮海岸树木模型，进行了水力学试验，既检验了数值模拟结果的准确性，又掌握了海岸森林中的海啸淹没现象，并通过试验和野外调查证实，面对大海的海岸树木可以受到大的脉冲流体力的作用。基于所开发方法的数值模拟，研究了海岸森林平面形状和生长对海啸抬高的影响。此外，通过对2011年东北地震海啸的实地调查，说明了沿海森林在减少海啸能量方面的作用和限度。

A judgment graph of lodging, uprooting and breaking for coastal black pine trees was proposed. An estimation method (numerical simulation method), integrated the conditions of lodging, uprooting and breaking, for the degree of tsunami energy reduction due to coastal forests was developed. Using low and high coastal tree models made by considering the similarity law for the trees, hydraulic experiments aimed to not only check the accuracy of numerical simulation results but also grasp the tsunami inundation phenomena in the coastal forests were carried out and it was confirmed through both the experiments and field surveys that large impulsive fluid force can act on coastal trees facing the sea. Based on numerical simulations by the developed method, effects of the plane shape and growth of coastal forest on the tsunami run-up were examined. Moreover, effects and limits of coastal forests on the reduction of tsunami energy were illustrated through the field survey of the 2011 Tohoku Earthquake Tsunami.