厦门岛海滩剖面对9914号台风大浪波动力的快速响应

A rapid response to 9914 typhoon-induced storm wave force made by the beach profiles of Xiamen Island

根据 9914号台风发生前后对厦门岛滨岸海滩剖面地形的重复测量结果及有关台风要素和潮位的实测资料 ,探讨了台风袭击厦门岛期间海滩的变形特征和侵蚀状态。分析得出 ,海滩地形受台风暴浪冲击普遍发生急剧变化。横向冲淤变形以东岸海滩为最剧烈 :滩肩蚀退可达 2 5m ;滩面呈上冲下淤 ,上段和滩肩的单宽冲蚀量达 30m3 /m ;下段单宽淤积量达 17m3 /m ;剖面类型由滩肩式断面向沙坝式断面转变。这种变形特点是在台风大浪波动力和潮位暴涨的双重作用下造成的。台风期间 ,沿岸输沙能力以北岸最高 ,南岸次之 ,东岸较低 ;且自南岸到东岸 ,随着沿岸输沙量减少 ,横向变形相应有增大的趋势。这是9914号台风以偏东方向袭击厦门的结果。表明不同方向海岸岸滩地形对同一台风大浪波动力作用具有不同响应特征。

The beach deformation and erosion during 9914 typhoon against Xiamen Island are studied in the paper, according to both the repeated topographic survey of the beach profiles of Xiamen Island and the determined data of tidal level and wind elements for 9914 typhoon. It is drawn from the study that rapid changes of the beach topography commonly take place due to the attack of wave forces. Beach profile deformation along the east coast of the Island is more radical where the retreat of ordinary berm crest may come up to 25 m, the above MSL profile erosion may reach 30 m 3/m, the under MSL profile accretion caused by mass transport of waves may attain 17 m 3/m. This unusual onshore offshore transport indicates that the beach profiles made a rapid response to both the action of the storm wave force and that of the storm surge. As for the net longshore transport rate, the north coast occupies the first place; the south coast comes the second; and the east coast is the lowest. From the south coast to the east coast, the net longshore transport rate becomes gradually lower, but the beach profile deformation is strengthened progressively. All this was caused by 9914 typhoon against Xiamen Island mainly with an easterly wind.