Abstract:

Runoff and sediment conditions of the Jinghe River were categorized into rich, normal and poor states, by using a P-III-type distribution and the data series at Zhangjiashan hydrological station from 1932 to 2008, and the evolution trend of runoff-sediment combination (RSC) was examined by the theory of Markov processes. An analysis of transient probability shows that the combinations tend to be rich-rich or poor-poor. In synchronous self-transient probability, rich-rich combination is the most probable with a value of 0.72, while in asynchronous self-transient probability, normal-poor is the most probable with a value of 0.50, and the synchronous-asynchronous transient probability of poor-normal combination is greater. An analysis of RSC encounter risks with the Copula method reveals that rich-rich encounter risk is the highest value of 27.9% in synchronous frequency, but differences exist in asynchronous ones. In general, the synchronous encounter frequencies are higher than the asynchronous ones. Finally, an analysis on the recurrence period of RSC is presented.