Abstract A hybrid tsunami defense system comprising vegetation (V), an embankment (E), and a moat (M) while changing the order of the components and the inundation depth of vegetation was investigated in a flume using a surge-type flow produced by quickly lifting a gate. Compared with the hybrid defense system in which vegetation is emergent, the tsunami mitigation effects of seaward vegetation became smaller than the other types because the reflections were weakened by the reduction of vegetation resistance in the submerged condition. Based on the decrease in overflow volume, fluid force, and moment by fluid force, the optimal structures of seaward and landward submerged vegetation types were the same order of ‘V, M, and E (VME type)’ and ‘E, M, and V (EMV type)’ from seaward, respectively, as those in the emergent condition. Differences in tsunami mitigation effects due to vegetation renewal were demonstrated in VME and EMV types by changing the horizontal vegetation structure. Although the mitigation effects of horizontally combined types were in between emergent and submerged conditions, the water surface gradient behind the forest, which is related to erosion and driftwood production, showed a clear difference in the order of submerged and emergent vegetation.

中文翻译：

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由堤防、护城河和森林组成的混合海啸防御系统在淹没、紧急或组合条件下的有效性差异

摘要 以植被 (V)、堤防 (E) 和护城河 (M) 组成的混合海啸防御系统同时改变组件的顺序和植被的淹没深度，在水槽中使用由水槽产生的涌流进行了研究。快速举起一道闸门。与植被突现的混合防御系统相比，由于在淹没条件下植被抵抗力的降低，反射减弱，因此向海植被的海啸减缓效果比其他类型小。基于溢流量、流体力和流体力力矩的减小，向海和向陆淹没植被类型的最佳结构为'V、M、E（VME型）'和'E、M、和 V（EMV 型）' 分别来自向海，与紧急情况下的一样。通过改变水平植被结构，在 VME 和 EMV 类型中证明了由于植被更新而导致的海啸缓解效果的差异。虽然水平组合类型的减缓效果介于挺水和沉水之间，但与侵蚀和浮木生产相关的林后水面梯度在沉水和挺水植被的顺序上表现出明显的差异。