基于DFA的长江上游径流演化标度特性研究

针对河川径流时序所具有的非线性与非平稳性特征，运用消除趋势波动分析法（Detrended Fluctuation Analysis，DFA）对长江上游控制性水文站-宜昌站1878～2001年的月均流量时序的演化特征进行了研究，以揭示该流域河川径流的长程相关性及其内在规律性。结果表明：长江上游河川径流时序波动具有长程相关性，且其标度指数具有显著的区域性，即在短时间尺度上具有强烈的正持续性，在长时间尺度上具有强烈的负持续性，且其正持续性至多可持续19个月，显示了长江上游流域产汇流系统演化具有复杂的物理机制

DFA based study on scaling property of runoff evolvement of Upper Yangtze River

In accordance with the non linear and non steady features of the river runoff time series， the evolvement characteristics of the time series of the monthly average flow rates from 1878 to 2001 of Yichang Hydrological Station——a control station on the Upper Yangtze River is studied herein based on the Detrended Fluctuation Analysis（DFA）， so as to reveal the long range correlation of the river runoff within the river basin and its inherent law.The result shows that the fluctuation of the river runoff time series of the Upper Yangtze River has a long range correlation and its scaling index has obvious regionality， i.e.a strong positive durative is on a short time scale there， while a strong negative durative is there on a long time scale， moreover， the positive can only continue for 19 months at the longest; which shows a complicated physical mechanism of the evolvement of the runoff and convergence system within the basin of the Upper Yangtze River.