广东省14个海滩裂流类型及统计特征分析

Types and statistical analysis of rip currents at 14 beaches in the Guangdong Province

裂流是沿海地区频发的一种高速离岸流。根据Castelle的裂流分类模型对广东省14个海滩的Google Earth影像进行了解译分类,对裂流分类模型在遥感影像中的应用进行了探讨。结果表明:在高风险月份,海滩裂流的组成较为单一,混合型裂流少,水深控制的裂流占据主导地位,裂流数量总体维持在较高水平;在中风险月份,水动力控制的裂流和混合型裂流的比例增加,水深控制的裂流仍然占有一定比例;在低风险月份,裂流很少出现,甚至无裂流发生。裂流的类型与海滩的状态密切相关。对于海湾中的海滩,海湾长度影响裂流的数量,海湾凹入度影响不同类型裂流的组成比例。考虑到实验条件的限制,这一规律需要后续结合实际地形地貌进行更细致和深入的研究和验证。按照本文解译标准得出的分类结果,与前人提出的裂流风险性评价模型吻合度较高,进一步说明了该解译标准的有效性,为今后对海滩裂流的研究和分类工作提供了一定的参考。

Rip current is a kind of high speed offshore current which occurs frequently in coastal.Based on Cas-telle’s rip current classification model,Google Earth images of 14 beaches in Guangdong Province were inter-preted and classified,and the application of rip current classification model in remote sensing images was dis-cussed.The results show that in high risk months,the composition of rip currents is relatively simple,the mixed rips are few,and the bathymetrically-controlled rip currents play a dominant role,and the number of rip currents re-mains at a high level.In the middle risk months,the proportion of hydrodynamically-controlled rip currents and mixed rips increases,while the proportion of bathymetrically-controlled rip currents still has a certain proportion.There is little or no rip currents in low-risk months.The structure of rip current is closely related to the state of beach.For the beach in the bay,the length of the bay affects the number of rip currents,and the concave degree of the bay affects the composition ratio of different types of rip currents.Considering the limitations of experimental conditions,this law needs to be further studied and verified in combination with the actual terrain and landform.The classification results obtained according to the interpretation criteria presented in this paper are in good agree-ment with the risk evaluation model proposed by previous authors,which further demonstrates the effectiveness of the interpretation criteria and provides some reference value for the future research and classification of rip cur-rents.