洪泽湖入湖水沙序列的多时间尺度小波分析

Multi-time scale wavelet analysis of streamflow and sediment sequences into Hongze Lake

为了分析洪泽湖入湖水沙序列的多时间尺度变化过程及特征,预测洪泽湖入湖水沙变化趋势,利用洪泽湖1975—2015年的年来水、来沙量数据,在统计分析的基础上,对洪泽湖年来水、来沙序列进行延伸和距平处理,采用小波分析方法对处理后的洪泽湖入湖水沙距平序列进行Morlet连续复小波变换,得到了小波变换系数的实部等值线图和模方等值线图,小波方差图和主周期变化趋势图。结果表明:洪泽湖近41 a年来水、来沙序列存在着多时间尺度特征,在不同的时间尺度下,洪泽湖年来水、来沙量丰枯变化趋势不同;年来水、来沙序列存在着同样的第一主周期,为30a特征尺度,在该特征尺度下,预测2015年之后未来短时间内洪泽湖年来水量、来沙量将分别进入到枯水期和少沙期且都将处于相应的峰值期。

In order to analyze the multi-time-scale variation process and characteristics of streamflow and sediment sequences into Hongze Lake and predict the trend of streamflow and sediment variation into Hongze Lake, based on the data of annual streamflow and sediment into Hongze Lake from 1975 to 2015, the streamflow and sediment sequences into Hongze Lake are extended and anomalous processed based on the statistical analysis. Morlet complex continuous wavelet transform is used to analyze the multi-time scale variation characteristics of the processed streamflow and sediment sequences into Hongze Lake. The real part contour maps and modulus contour maps of the wavelet transform coefficients, the wavelet variance maps and the trend maps of the main period change are obtained. The results show that the streamflow and sediment into Hongze Lake in recent 41 years have multi-time scale characteristics. Under different time scales, the annual streamflow and sediment into Hongze Lake have different trends, and the streamflow and sediment sequences into Hongze Lake have the same first main cycle, which is the 30-year characteristic scale. Based on the 30-year characteristic scale, it is predicted that the annual streamflow and sediment into Hongze Lake will enter the dry season and the low sediment season respectively in the short time after 2015 and will be in the corresponding peak period.