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以混沌理论为基础,提出了河流混沌特性分析方法。选择对河流演变有重要影响的宽深比时间序列和水沙时间序列,首先对这些时间序列进行相空间重构,计算不同河型的宽深比、径流量和含沙量时间序列的饱和关联维数和最大Lyapunov指数,然后通过求这些时间序列的饱和关联维数的加权平均值和最大Lyapunov指数的加权平均值,得出不同河型的混沌特性。以黄河下游的6个河段3种河型为例,对宽深比、径流量和含沙量时间序列,分别进行混沌特性分析。研究结果表明,河流演变具有明显的混沌特性,但不同河型表现出的混沌特性不同,游荡河型混沌特性较强,弯曲河型混沌特性较弱。通过对河流混沌特性分析,有助于加深对河流演变预测的进一步认识。根据混沌理论,混沌系统短期行为可以预测,而长期不能预测。所以,河流演变预测是短期可行,长期很难预测、甚至是不可预测的。
Based on chaos theory, a method of analyzing the chaos characteristics of rivers is proposed. Firstly, the space-time reconstruction of these time series is first selected to calculate the ratio of aspect ratio, runoff and sediment concentration time series of different river patterns Dimension and the largest Lyapunov exponent, and then obtain the chaotic characteristics of different river types by calculating the weighted average of the saturation correlation dimension and the weighted average of the maximum Lyapunov exponents of these time series. Taking the 6 types of river sections in the lower reaches of the Yellow River as an example, chaotic characteristics were respectively analyzed for the time series of width-depth ratio, runoff and sediment concentration. The results show that the evolution of the river has obvious chaotic characteristics, but the chaotic characteristics of different river types are different. The chaotic characteristics of the wandering river are stronger and the chaotic characteristics of the curved river are weaker. By analyzing the chaotic characteristics of rivers, it is helpful to deepen the further understanding of the prediction of river evolution. According to chaos theory, short-term behavior of chaotic system can be predicted, but not predicted in the long term. Therefore, the forecast of river evolution is feasible in the short term, and it is hard to predict in the long term or even unpredictable.