ABSTRACT Countermeasures are investigated against coastal erosion and sediment invasion around a half-buried floodway through a series of small-scale physical model experimentations. Further, countermeasures are proposed to shorten the protruded length of the floodway across the shoreline to prevent interruption of longshore sediment transport and to excavate downdrift sediments at the mouth of the floodway to minimize the downdrift erosion as well as the sedimentation inside the floodway. Results of the study show that the shortened floodway is successful in mitigating downdrift erosion, while continuous downdrift excavation is proven to be significantly effective in reducing sedimentation inside the floodway when excavation is implemented with the same order-of-magnitude of the longshore sand transport rate. Attention must be paid, however, on the effect of wave randomness and floodway discharge during stormy waves as they further increase sedimentation inside the floodway apparently owing to onshore sediment movement enhanced by asymmetric horizontal acceleration and to a large skewness in the water particle velocity at the mouth of the floodway.

中文翻译：

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半掩埋泄洪道周边海岸侵蚀泥沙入侵对策研究

摘要 通过一系列小规模物理模型实验，研究了半掩埋泄洪道周围海岸侵蚀和泥沙入侵的对策。此外，还提出了缩短泄洪道跨海岸线突出长度的对策，以防止沿岸泥沙输运中断，并在泄洪道口挖掘下流沉积物，以尽量减少下流侵蚀和泄洪道内的沉积。研究结果表明，缩短的泄洪道成功减轻了下流侵蚀，而当以与沿岸输沙率相同的数量级进行开挖时，连续下流开挖被证明对减少泄洪道内的沉积作用显着有效。 . 不过需要注意的是，