基于小波分析的长江南京段分级水位研究

Research on graded water level of Nanjing section of Yangtze River based on wavelet analysis

为研究长江南京段高低潮水位的分级等问题,采用Mann-Kendall检验、复Morlet小波分析法分析了南京潮水位站1950~2020年潮水位的变化趋势、周期。采用滑动平均序列提取趋势项法量化潮位的变化趋势,对南京潮水位站的年最高、最低潮位进行修正。采用频率分析方法推求对应频率90%下的高水位、50%下的中水位及10%下的低水位。计算思路及成果为长江南京段高低潮水位的分级研究、生态水位及水资源的保护利用等提供一定的科学依据。结果表明:南京潮水位站年均潮水位变化趋势不明显,年最高潮水位、年最低潮水位序列存在明显的增加趋势;年均潮水位、年最高潮水位、年最低潮水位周期为10,15,14 a,且南京潮水位站年最高潮、最低水位序列的次周期均同为9 a,年最高潮水位与年最低潮水位的变化波动尺度比较接近。

In order to classify the high and low tide levels in the Nanjing section of the Yangtze River,Mann-Kend⁃all test and complex Morlet wavelet analysis were used to analyze the trend and cycle of the tide level at the Nanjing tide station from 1950 to 2020.The moving average sequence is used to extract the trend item to quantify the trend of the tide level,and the annual maximum and minimum tide levels of the Nanjing tide level station are corrected.The frequency analysis method is used to calculate the high water level at 90%frequency,the medium water level at 50%frequency,and the low water level at 10%frequency.The calculation ideas and results can provide a certain scientific basis for the classification study of the high and low tide water levels of the Nanjing.The analysis showed that the annual average tidal level change trend at Nanjing tide water level station is not obvious,and the annual highest tide water level and the annual lowest tide water level sequence have an obvious increasing trend;the annual average tidal water level,annual highest tide water level,and annual lowest tide water level cycle are 10 years,15 years,14 years,and the sub-periods of the annual highest tide and lowest water level sequence at the Nanjing tide water level station are all 9 years,and the fluctuation scales of the annual highest tide water level and the annual lowest tide water level are relatively close.Section of the Yangtze River,the ecological water level and the protec⁃tion and utilization of water resources.