不同周期分潮簇对复杂河网潮位分布的影响

Relationship of tidal level and different tidal species in complex river networks

在不规则半日潮为主的河口,半日和全日周期的分潮簇在很大程度上影响了潮位的振幅。但当潮波向三角洲河网内部传播时,由于不同周期分潮簇的振幅沿程变化速率存在差异,特别是半月周期分潮簇振幅作用得到增强,使得不同周期分潮簇对河网内潮位分布的影响具有明显的区域性特征。通过珠江三角洲河网一维水动力模型得到研究区域内高频且长周期的潮位资料,基于小波分解重构出主要周期分潮簇的振幅,采用谱聚类图像分割算法,通过像素分割计算确定综合相似度,从图像学等角度论证了不同周期分潮簇与复杂河网潮位分布的空间关联性。研究发现,半日和全日周期的分潮簇影响了复杂河网口门潮位振幅的量值,但半月周期的分潮簇却影响了复杂河网整体潮位分布的形态特征。

The surface level variation greatly depends on semidiurnal and diurnal tidal species in the estuaries of irregularly semidiurnal tides. However, fortnightly tidal species have a great impact on the mean water surface topography upriver due to substantial difference in damping of the main different tidal species. Therefore, the effect of different tidal species on tidal level distribution has obviously regional characteristics when tides propagate into deltaic river networks. In this paper, a one-dimensional flow model of the Pearl River networks was used to obtain a series of high-frequency and long-period tidal levels. Then, spatial distributions of the four main tidal species in the study area were obtained for further study by continuous wavelet transformation(CWT) and reconstruction. Finally, a new pixel affinity for spectral image segmentation was employed to compare the similarity between two figures, which implied a spatial correlation of tidal species and tidal level distribution in the complex river network. The results showed that surface level variation is influenced by semi-diurnal and diurnal tidal species near the outlets, while mean water surface topography is influenced by fortnightly tidal species in the complex river network.