LI Hong-liang, LIU Dong-xu
Hydrological Bureau , YRCC£¬China Zhengzhou 475004

Abstract: the length of annual runoff at Qingtongxia station and Shanxian station were extrapolated to 278 years and 236 years respectively with recorded stakes flow rising information in Qing dynasty. the variety of natural flow of Yellow River has obviously presented periodical change of rich and dry flow with uncertainty period through analysis on long term natural runoff. The variety of natural flow of Qingtongxia and Shanxian for many years is basically, but incompletely identical; the representative analysis of the series of natural flow shows that the upper stream and down stream should separate, the series length of natural flow for Qingtongxia is not little less than 83 years, the series length of natural flow of Shanxian is not little less than 70 years, the variety of average value just tend to stability basically. here are three times that the withered water segment with continued eleven years appears in 236 years series for Shanxian; According to the data analysis in last few years, the withered water segment from 1990 to 2000 hasn't ended by 2002.

Key words: Yellow River; variety of natural flow; representative analysis; variety characteristic