Local scour by inundating tsunami currents on the land side of coastal forests can greatly decrease the tsunami mitigation advantage of the forest by producing driftwood. The purpose of this study was to analyze the scour profiles inside and behind a forest model (FM) due to the flow passing through it, and to compare the scour phenomenon around fixed and moveable bed cases within the FM. Two series of flume experiments were conducted by changing initial water depths (water depth without FM in the flume, h_o = 3 cm to 7 cm), densities of FM (dense G/d = 0.25, intermediate G/d = 1.09, and sparse G/d = 2.13, where G = clear spacing between each cylinder in a cross-stream direction, d = diameter of a cylinder) and vegetation thicknesses (dn) of 180, 380, and 580 No.cm. In series 1 and 2, experiments were performed with a fixed bed inside FM for the three vegetation densities and for moveable bed case only for the intermediate density, respectively. Downstream scour profiles behind FM, backwater rise, and water surface gradient inside FM were investigated. For the fixed bed case, minimum scour was measured in the intermediate FM case for the three densities of 180, 380, and 580 No.cm. In the fixed bed inside FM, the location of maximum scouring moved away from the downstream end of FM while in cases of a moveable bed inside FM, the location of maximum scour moved towards the downstream end inside FM. Scour inside coastal forest damages the trees; therefore, it is recommended to stabilize the bed inside the forest by planting grasses, etc., if there is no constraint on the light environment inside the forest and the space behind the forest where local scour occurs.

中文翻译：

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洪泛海流冲刷沿海植被下游的实验研究

通过在沿海森林的陆地侧淹没海啸流来进行局部冲刷，可通过生产浮木大大降低森林的海啸缓解优势。这项研究的目的是分析森林模型（FM）内部和后面由于水流而引起的冲刷情况，并比较FM内固定床和可移动床箱周围的冲刷现象。两个系列的水槽实验由（在水槽，水深度而不FM改变初始的水深进行ħ _ø  = 3 2cm至7cm），FM的密度（密集ģ / d  = 0.25，中间ģ / d  = 1.09，并且稀疏G / d  = 2.13，其中G =在横流方向上每个气缸之间的净间距d =圆柱直径）和180、380和580 No.cm的植物厚度（dn）。在系列1和2中，分别在FM内的固定床上进行了三种植被密度的实验，而在活动床箱上仅针对中间密度进行了实验。FM后的下游冲刷剖面，死水上升和FM内部的水面梯度已得到调查。对于固定床箱，在三种FM密度为180、380和580 No.cm的情况下，在中频FM箱中测量的最小冲刷量。在FM内的固定床中，最大冲刷位置远离FM的下游端，而在FM内可移动床的情况下，最大冲刷位置向FM内的下游端移动。沿海森林的冲刷破坏了树木；因此，