黄河主要断面泥沙时序可预报时间及趋势分析

Predictable time and trend analysis of the sediment time series at some control sections along the Yellow River

选取黄河头道拐、潼关、花园口和利津断面1952—2000年的泥沙含量为时序，分别计算了泥沙时序的K2熵和Hurst指数。结果表明，各断面的款熵变化在0．13～0．38之间，说明黄河流域各级系统均具有混沌特征，并且从上游到下游混沌特性逐渐增强。随着混沌特性的增强其平均可预报时间下降，头道拐断面的可预报时间8a，其余断面为3a。各断面Hurst指数均大于0．68，在可预报时间内泥沙时序具有持续性下降趋势，并用2001—2004年实际数据进行了验证。

Sediment concentrations from 1952 to 2000 were chosen as the time series at Toudaoguai section, Tongguan section, Huayuankou section and Lijin section along the Yellow River. Kolmogorov entropy（ K2 ）^-2 was calculated according to Zhao Gui-bing arithmetic, and Hurst index（H） according to R/S analysis. The results show that （1） Kolmogorov entropy is 0.13 at Toudaoguai section, 0.37 at Tongguan section, 0.40 at Huayuankou section and 0.38 at Lijin section, so the dynamic systems controlled by the different sections of the Yellow River basin are chaotic systems and the chaotic degrees heighten gradually from the upper to lower section. （2） At Toudaoguai section, the forecast time of the sediment time series is about 8 years, and the other sections are 3 years. The more obvious the chaos is, the shorter the forecast time is. （3） Hurst indexes at all study sections are more .than 0.5, the maximum is 0.86 at Tongguan section and the minimum is 0.68 at Toudaoguai section, which indicates that the changes of the time series have continuous descending trends.