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河道水沙变化过程具有非线性特征,基于长江寸滩站、朱沱站和嘉陵江北碚站(简称“三站”)1955-2011年的水文资料,应用多重分形消除趋势波动分析法(MF-DFA方法),研究长江重庆河段水沙变化过程的多重分形特征。结果表明:三站日流量和日输沙率序列具有多重分形特征,该多重分形特征是由序列的长程相关性引起的;日流量序列的奇异谱呈右钩状曲线,小涨落的影响在序列中占优势,日输沙率序列的奇异谱对称,大小涨落的标度行为在序列中基本一致;水沙时序变化的复杂程度可用多重分形谱宽Δα表征,且日输沙率序列的Δα相对较大,变化更为复杂;不同时段水沙序列的谱曲线形状存在较大差异,丰水丰沙时序的谱曲线较宽,顶部较圆滑,Δα较大,枯水枯沙时序的谱曲线较窄,顶部较尖锐,Δα较小。
Based on the hydrological data from 1955-2011 of the Yangtze River Cuntan Station, Zhu Tuo Station and Jialing River Beijiao Station (referred to as “Three Stations”), the process of multifractal elimination trend fluctuation analysis (MF -DFA method) to study the multifractal characteristics of water and sediment variation in the Chongqing reach of the Yangtze River. The results show that the daily flow rate and the daily sediment transport rate of the three stations have multifractal characteristics. The multifractal characteristics are caused by the long-range correlation of the sequences. The singular spectrum of the daily flow rate series shows a right hook curve, In the sequence, the singular spectral symmetry of the daily sediment transport rate series and the scaling behavior of the size fluctuations are basically the same in the sequence. The complexity of the time series variation of water and sediment can be characterized by the multifractal spectrum width Δα, and the daily sediment transport rate series Δα is relatively large, and the change is more complicated. The shape and shape of the spectral curves of water and sediment sequences are quite different in different periods. The abundance curve of Fengshesu sequence has a wide spectral curve, a smoother top and a larger Δα, The curve is narrower, the top is sharper, and Δα is smaller.