Estuarine flow is the fundamental driving of physical processes such as estuarine ecological environment, river evolution and material transport. Due to the runoff, tide, topography and meteorology, the estuarine flow presents a complex three-dimensional structure, including not only the residual flow induced by fresh water injection, but also the periodical tidal current, wind-driven flow, baroclinic flow and the residual flow caused by estuarine nonlinearity. In order to explore the composition and intra-tidal variation of estuarine flow, based on the field data in the Oujiang River Estuary, the estuarine flow is decomposed by principal component analysis (PCA) method, and the decomposition performance of PCA method for estuarine flow and high-frequency characteristics of baroclinic overtide are deeply discussed. The results show that PCA method can operate original data or standardized data in the study of estuarine flow structure. PCA method can decompose baroclinic components (estuarine gravitational circulation structure), but cannot separate barotropic components (runoff and tidal current). The coupled effect of runoff and tidal current is reflected in the score of principal components. The filter of principal components should employ conjoint judgment of flow structure and cumulative interpretation variance, rather than only cumulative interpretation variance. The estuarine baroclinic flow has clearly high-frequency characteristics, which approximates quarter-diurnal.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |