粤东后江湾冲流带滩面高频振动及动力作用分析

Analysis of Beach Face High Frequency Oscillations and Dynamic Actions in the Swash Zone of the Houjiang Bay of Guangdong Province

利用涌浪影响下短时段内的冲流带滩面高频高程数据和碎波带波流资料,在奇异谱分析(SSA)的基础上,对比研究了不同形态滩面的冲淤变化趋势、趋势分布形状、冲淤变化周期和冲淤变化强度,以及同一条剖面不同桩点间各因素间的变化关系;用交叉谱方法探索了每分钟滩面高频冲淤变化与碎波带长重力波间的作用关系。分析结果表明,滩角韵律地形引起的冲流分流作用促进了滩脊向滩谷的泥沙转运,冲流带滩面存在明显的长重力波频段的周期性冲淤振动,滩面冲淤振动强度由滩面下部向上部递减,碎波带长重力波对滩面高频冲淤变化起重要作用。

In this paper, the beach face high frequency oscillation, wave and current data in the surf zone are used to study the beach face variation trends, trend distributions, oscillation periods and oscillation intensities for different beach profles and the variation relations between different factors between different stake points on the same profile by using singular spectrum analysis (SSA), and the relations between beach face high frequency oscillations and infragravity waves in the surf zone are also explored by using cross spectrum analysis. It is shown from the analysis results that the swash diffluences caused by the beach cusp rhythm topography promote the sediment transport from beach ridge to beach trough, and there are obvious beach face periodic oscillations with infragravity wave frequencies in the swash zone. The beach face oscillation intensities decrease from bottom part to upper part of beach face, and the infragravity waves in the surf zone play an important role in generating the beach face high frequency oscillations.