福建江田下沙沙滩沉积地貌组合对台风的响应模式

利用福建长乐江田下沙砂质海滩台风前后两次野外调查资料,探讨了该处沙滩地貌和沉积物组合分布的基本特征;初步研究了该处沙滩对0418号台风“艾利”的响应模式.研究结果表明,下沙沙滩剖面沉积物以细砂和中细砂为主,台风前后采集的18个样品中,细砂6个,占总样品量的33%;中细砂11个,占总样品量的61%.沉积物结构上具有三维均匀性,沉积特征单一.剖面地形具有典型的夷直海岸特点,前滨滩面宽阔平坦,后滨沙丘带发育,岸线平直.受台风“艾利”作用,剖面后滨和高潮带遭受严重侵蚀,后滨低沙丘带平均蚀退超过6m,并出现高度为0.5~1.0m间的直立侵蚀陡坎.海滩沉积物对台风的响应相对较弱,台风过后剖面表层沉积物的平均粒径(Mz)均值由2.48变为2.39,粒度稍有变大;分选系数(σi)平均值由0.52变为0.63,分选稍有变差;偏度(Ski)平均值由-0.02变为0.01,峰态(Kg)平均值由0.96变为1.13;偏度和峰度没有明显变化.剖面底层沉积物对0418号台风“艾利”的响应特征与表层沉积物的沉积响应相似.

Typhoon response model of sedimentary and geomorphological associations on Xiasha beach, Jiangtian, Fujian

By comparing the data obtained in two field investigations on the sandy beach of Xiasha, Jiangtian, Changle, Fujian, before and after No.0418 typhoon "Aere", the basic feature of the (sedimentary) and geomorphological associations on the beach is discussed, and its response model to "Aere" is studied preliminarily. The result showed that Xiasha beach profile are mainly composed of fine sand and mid-fine sand with an even construction in three dimensions and a simple sedimentary characteristic. Among the 18 samples of this profile, there are 6 fine sand with a proportion of 33% of total samples and 11 mid-fine sand with a proportion 61% of total samples. The profile morphology presents a typical feature of the straightened beach. Its foreshore is broad and smooth, its backshore consists of dunes and its coastline is rather straight. Suffering from "Aere", the backshore dunes and the high tide zone on Xiasha beach were eroded severely. The foredunes retreated over 6 m and perpendicular beach scarps 0.5 to 1 m high occurred. The response of the sedimentary characteristic to the typhoon is relatively light. After "Aere", the surface sediments mean sizes () changed from 2.48 to 2.39;sorting coefficients from 0.52 to 0.63,skewness from -0.02 to 0.01, kurtosis from 0.96 to 1.13 by average. The feature of the bottom sediments responsing to typhoon on Xiasha profile is similar to its surface sediments.