Field Surveys and Numerical Simulation of the 2018 Typhoon Jebi: Impact of High Waves and Storm Surge in Semi-enclosed Osaka Bay, Japan
Field Surveys and Numerical Simulation of the 2018 Typhoon Jebi: Impact of High Waves and Storm Surge in Semi-enclosed Osaka Bay, Japan
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2018年台风飞燕的实地调查和数值模拟：日本半封闭大阪湾的巨浪和风暴潮的影响
DOI：
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发表时间：
2019
影响因子：
2
通讯作者：
Atsuhei Takahashi
中科院分区：
文献类型：
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作者：
T. Le;H. Takagi;M. Heidarzadeh;Yoshihumi Takata;Atsuhei Takahashi
2018年，台风“飞燕”登陆日本，9月4日袭击大坂湾，给日本第二大经济区关西地区造成严重破坏。在台风“飞燕”来袭后，我们立即对大坂、和歌山、德岛、兵库县、淡路岛等大坂湾周边地区进行了实地调查，对这些地区的情况进行了评估。杰比在这些地区的大片地区产生了大浪，许多海岸因大浪和风暴潮的共同影响而受到严重破坏。此次风暴潮是大坂有史以来最高的。我们使用了风暴潮波耦合模式来调查的影响所造成的Jebi。利用3个验潮站的真实的实测资料对模拟的涌浪位进行了验证，利用4个波浪监测站的实测资料对波浪模拟结果进行了验证。该模型的高精度表明，数值模拟可用于估计特定地点的风暴潮和风浪高度，特别是在没有监测站的地方。根据模拟结果，在德岛和和歌山之间的纪伊海峡入口处的有效波高约为13 m，大坂湾内的有效波高约为4 m。在实地考察过程中，我们遇到了倒塌的海堤，这些海堤明显受到了高浪的破坏。事实上，在兵库县的科比，风暴潮只比正常潮位高出1.7米，并不是特别高。因此，风暴潮和巨浪的结合可以解释兵库县的破坏程度，例如在实地调查期间观察到的内陆防洪闸失灵和防波堤上搁浅的大型船只。我们强调，即使在半封闭的海湾，适当的海岸设计对高波的重要性，因为他们似乎被低估时，台风灾害风险管理进行。
Typhoon Jebi made landfall in Japan in 2018 and hit Osaka Bay on September 4, causing severe damage to Kansai area, Japan’s second largest economical region. We conducted field surveys around the Osaka Bay including the cities of Osaka, Wakayama, Tokushima, Hyogo, and the island of Awaji-shima to evaluate the situation of these areas immediately after Typhoon Jebi struck. Jebi generated high waves over large areas in these regions, and many coasts were substantially damaged by the combined impact of high waves and storm surges. The Jebi storm surge was the highest in the recorded history of Osaka. We used a storm surge–wave coupled model to investigate the impact caused by Jebi. The simulated surge level was validated with real data acquired from three tidal stations, while the wave simulation results were verified with observed data from four wave monitoring stations. The high accuracy of the model demonstrates the usefulness of numerical simulations to estimate the heights of storm surges and wind waves at specific locations, especially where no monitoring stations are available. According to the simulation, the significant wave height was nearly 13 m in the entrance of Kii Strait between Tokushima and Wakayama and 4 m inside Osaka Bay. During the field survey, we encountered collapsed sea dykes, which were obviously damaged by high waves. In fact, the storm surge reached only 1.7 m above the normal tidal level at Kobe, Hyogo, which was not extremely high. Hence, the combination of storm surge and high waves can explain the extent of destruction in Hyogo, such as the failure of an inland floodgate and a stranded large vessel over the breakwater, which were observed during the field survey. We emphasize the importance of adequate coastal designs against high waves even in semi-enclosed bays, as they seem to have been underestimated when the typhoon disaster risk management was conducted.