长江下游感潮河段极值水位的周期分析

Analysis of the periodicity of yearly extreme water level in the tidal reaches of the Yangtze River

采用周期图法和最大熵谱法两种谱分析方法,研究了长江下游感潮河段芜湖、南京、江阴3个水文站1964—1987年共24 a的年最高水位及年最低水位的周期特征。发现芜湖、南京、江阴的年最高水位都具有3.14 a的周期,芜湖、南京还提取了7.33,2.2 a的周期,江阴还有5.5 a的周期。芜湖、南京、江阴的年最低水位序列都提取有2.44～3.14 a的周期,芜湖、南京、江阴还分别有2.2,5.5,11 a的周期。提取出的这些周期既反映了长江径流的周期特性,也体现了海洋潮汐的周期特性,从而为研究长江下游感潮河段的年际变化规律提供了科学依据。

The periodic characteristics of the time series of yearly highest water level and yearly lowest water level on the lower tidal reaches of the Yangtze River are analyzed by using periodogram analysis and maximum entropy spectrum analysis according to the data（1964-1987） of Wuhu,Nanjing and Jiangyin hydrologic stations.The results show that the period obtained in the yearly highest water level of Wuhu,Nanjing and Jiangyin is all 3.14 years,that obtained in the yearly highest water level of Wuhu and Nanjing is 7.33 and 2.2 years respectively,and that obtained in the yearly highest water level of Jiangyin is 5.5 years.The period obtained in the yearly lowest water level of Wuhu,Nanjing and Jiangyin is 2.443.14 years,and that obtained in the yearly lowest water level of Wuhu,Nanjing and Jiangyin is 2.2,5.5 and 11 years respectively.These periods not only reflect the periodic characteristics of runoff of the Yangtze River,but also represent those of ocean tide.It provides the foundation for further research of evolution of the lower tidal reaches of the Yangtze River.