海岸沙丘近表层粒度对台风的响应

根据“麦德姆”强台风登陆前后福建平潭岛海岸前丘、爬坡沙丘、横向沙丘和海岸沙席等海岸沙丘近表层的粒度数据，分析了台风登陆前后典型海岸沙丘近表层粒径组成与粒度参数的变化，初步总结了海岸沙丘近表层粒度对台风的响应特征。整体而言，平潭岛海岸沙丘在“麦德姆”登陆前后近表层的粒度变化较小，对台风的响应变化不大且基本无等级性的差别，但海岸沙丘不同类型及不同部位的响应程度并不一致，主要是由海岸沙丘沙与海滩沙粒度的相近性及台风过程中大风的非选择性风蚀所致，同时也受到不同类型沙丘的形态和规模等的影响。

Responses of Grain Size of Near Surface Layer over Coastal Dunes to Typhoon

Based on the grain size data of near surface layer over four types of coastal dunes in Pingtan Island before and after the tenth Typhoon Matmo landed in 2014, such as coastal foredune, climbing dune and transverse dune as well as coastal sand sheet, the grain size change of near surface layer over four types of coastal dunes in response to the typhoon Matmo event is analyzed. The results suggest that the basic feature of the impact of typhoon Matmo on the grain size of near surface layer over four types of coastal dunes is the low change magnitude of grain size composition and grain size parameters after the typhoon Matmo landing compared with before, there is no clear change of grain size over coastal dunes resulted from the typhoon Matmo in observation sample areas, but the magnitude of grain size change differs between different type of coastal dunes and the sites over the coastal dunes although the change magnitude of grain size is very small. The basic factors influencing the characteristics of the typhoon Matmo impact on the grain size of near surface layer over four types of coastal dunes are the aeolian sands of coastal dunes and the beach sands in Pingtan Island have no significantly sedimentological discrimination in grain size composition and grain size parameters, and the high-speed wind under the condition of typhoon Matmo landing resulted in the strong wind erosion which eroded all the different grain size sands of near surface layer over four types of coastal dunes, meanwhile the special shape and the volume of coastal dunes also could influence the typhoon impact degree of grain size of near surface layer over four types of coastal dunes.