Coastal vulnerability analysis during tsunami-induced levee overflow and breaching by a high-resolution flood model
Coastal vulnerability analysis during tsunami-induced levee overflow and breaching by a high-resolution flood model
复制标题
DOI：
10.1016/j.coastaleng.2015.10.007
复制
发表时间：
2016
影响因子：
4.4
通讯作者：
T. Shimozono;Shinji Sato
中科院分区：
文献类型：
--
作者：
T. Shimozono;Shinji Sato
沿海堤坝是低洼沿海地区的重要防御要素，但当水位急剧上升时，很容易溢出。本研究的重点是在2011年日本东北海啸中广泛观察到的向陆坡脚局部冲刷导致的混凝土铠装堤坝破坏。使用高分辨率的洪水模型与冲击捕捉属性，我们探讨了实际的突破过程及其对受破坏最严重的地区之一的保护区的影响。该模型是基于非线性浅水方程组，并成功地再现了详细的流动结构的海啸溢流在2米的分辨率。然而，由于我们忽略了陡峭堤坝斜坡上的非静水压力，模拟的溢流流量略有低估。在模拟过程中，超临界流发展的堤段的陆侧，尾水位缓慢上升，由于腹地的地形特征，尽管大的溢流流量。地形数据分析显示，大规模的冲刷坑或沟的位置处的超临界流的发展，这表明，堤坝的脆弱性可以识别的局部流动参数的基础上的高分辨率模型。堤坝决口被模拟为相应的堤坝部分的突然移动，并对其后果进行了研究。堤防决口改变了洪水强度的空间平衡，但在这种情况下，并没有显着恶化的损害，因为狭窄的低洼地区完全淹没，即使没有突破。
The coastal levee is a crucial defense element in low-lying coastal areas, but is vulnerable to overflow when water levels increase extremely. This study focuses on the failure of the concrete-armored levees caused by local scouring at the toe of their landward slope that was widely observed in the 2011 Tohoku tsunami in Japan. Using a high-resolution flood model with a shock-capturing property, we explore the actual breach processes and their impacts on the protected areas in one of the most devastated districts. The model is based on nonlinear shallow water equations and successfully reproduces detailed flow structures of the tsunami overflow at 2 m resolution. However, because we neglect the non-hydrostatic pressure over steep levee slopes, the modeled overflow discharge is slightly underestimated. During simulation, supercritical flow developed on the land side of levee sections with slowly rising tailwater water level due to hinterland topographic features, despite the large overflow discharge. Topographic data analysis revealed large-scale scour holes or trenches at the locations of the supercritical flow development, suggesting that levee vulnerability can be identified by the local flow parameters based on the high-resolution model. The levee breach was modeled as a sudden removal of the corresponding levee section, and the consequences were investigated. The levee breach changed the spatial balance of the flood intensity, but did not significantly worsen the damage in this case, because the narrow low-lying areas were fully inundated even without breach.