海滩剖面时空变化过程分析

Analysis on Spatial and Temporal Processes of Beach Profile Variations

利用粤西水东湾海滩重复测量的地形剖面，通过经验正交函数变换与小波变换，分析了剖面变化的主要空间过程及其时间振荡特性。结果显示，海滩剖面主要由占数据总方差９０％的３个空间过程构成：水下砂坝运移、滩肩进退和后滨侵蚀。三个主要空间过程在时频域具有多尺度的振荡周期性。其中，水下砂坝运动以准季节性变化为主，滩肩和后滨地形蚀积则显示出准２个月变化周期性。剖面变化主要过程与影响海区的台风作用密切相关。

Based on the repeatedly measured profile data in the middle section of the beach of the Shuidong Bay in west Guangdong, the main spatial processes of beach profiles and their temporal oscillations are analyzed with empirical orthogonal function and wavelet transform methods. The results show that the profile variations are mainly composed of three prodesses which accounted for 90% of the total variance of the original data: sub-tidal bar movement; berm progression and retrogression; and backshore erosions. Three main spatial processes indicate multi-scale oscillations in temporal and frequency domain, in which the variations of bar movements are mainly quasi-seasonal while the berm and backshore erosions exhibit the quasi-two month period. The main processes of profile changes are closely related to the typhoon actions.