Mangrove forest against dyke-break-induced tsunami on rapidly subsidingcoasts
Mangrove forest against dyke-break-induced tsunami on rapidly subsidingcoasts
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红树林抵御快速下沉海岸上堤坝溃决引发的海啸
DOI：
10.5194/nhess-16-1629-2016
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发表时间：
2016
影响因子：
4.6
通讯作者：
Shota Kurobe
中科院分区：
文献类型：
--
作者：
H. Takagi;Takahito Mikami;D. Fujii;M. Esteban;Shota Kurobe
抽象。通常在发展中国家发现的薄的沿海堤坝可能由于快速的地面沉降、材料老化、海平面上升、巨浪袭击、地震、山体滑坡或与船只碰撞而突然倒塌。这种失败可能引发溃坝海啸式的洪水，或“溃坝引发的海啸”，这种可能性迄今在沿海灾害科学和管理领域被忽视。为了分析由堤坝破坏引起的洪水事件的潜在后果，根据作者对印度尼西亚雅加达脆弱沿海地区的实地调查，构建了一个水动力学模型。在一个2米的地面沉降的情况下，预计将在大约10-20年后在研究区域发生，模型结果表明，洪水迅速上升到近3米的高度，类似于地震引发的海啸的洪水模式。深度-速度积准则表明，堤坝后面的许多狭窄的行人通道可能会遇到强烈的水流，远远超过允许行人疏散的安全限制。此外，还考虑了几种替代方案，以研究如何通过在堤坝前建立一个红树林带作为额外的安全措施来减轻洪水的影响。决堤引发的海啸在许多地区比一般的地震海啸发生的可能性大得多，不能忽视，因此在许多发展中国家的灾害管理和沿着城市规划中应加以考虑。
Abstract. Thin coastal dykes typically found in developing countries may suddenly collapse due to rapid land subsidence, material ageing, sea-level rise, high wave attack, earthquakes, landslides, or a collision with vessels. Such a failure could trigger dam-break tsunami-type flooding, or “dyke-break-induced tsunami”, a possibility which has so far been overlooked in the field of coastal disaster science and management. To analyse the potential consequences of one such flooding event caused by a dyke failure, a hydrodynamic model was constructed based on the authors' field surveys of a vulnerable coastal location in Jakarta, Indonesia. In a 2 m land subsidence scenario – which is expected to take place in the study area after only about 10–20 years – the model results show that the floodwaters rapidly rise to a height of nearly 3 m, resembling the flooding pattern of earthquake-induced tsunamis. The depth–velocity product criterion suggests that many of the narrow pedestrian paths behind the dyke could experience strong flows, which are far greater than the safe limits that would allow pedestrian evacuation. A couple of alternative scenarios were also considered to investigate how such flood impacts could be mitigated by creating a mangrove belt in front of the dyke as an additional safety measure. The dyke-break-induced tsunamis, which in many areas are far more likely than regular earthquake tsunamis, cannot be overlooked and thus should be considered in disaster management and urban planning along the coasts of many developing countries.