LAN YONGCHAO¹, DING YONGJIAN¹, CHEN XIANZHANG¹ & MA JIANHUA²

Abstract The runoff in the upper Yellow River basin above Tangnag has been decreasing recently due to global climate warming and human activity influences since the end of the 1980s. The decrease not only badly affects hydro-power and irrigation in the upper Yellow River areas, but also influences the environment of the whole Yellow River basin. Thus, it is necessary for the orderly development and utilization of water resources of the Yellow River basin to understand the future possible change, and the corresponding relationship between global warming with runoff in the upper Yellow River. The long-period evolution law and space–time distribution characteristics of the runoff in the Upper Yellow River are analysed based on data measured at some relational hydrometric and weather observation stations, and a new long-period trend forecast model called the Time Series—Markov Chain Forecast Model, are presented in this paper. The result shows that runoff in the upper Yellow River is located IN a low-flow period that started at the end of the 1980s, and the status will be changed in the future decade. The runoff will gradually increase in the future decade and mean runoff in the future decade will be larger than that in the former decade.