| In order to exactly determine the disturbance point of human activities to the runoff in Shiyang River,this paper analyzed the serial of runoff into the Hongyashan Reservoir in the lower reaches from 1956 to 2000 by R/S analysis(Rescaled Range Analysis).The results showed that,the aberrance year of the runoff sequence was 1977.There were significant differences between both the statistical eigenvalues and the regressive equations of the two sequences divided by 1977.This approximately accorded with the status of exploitation and use of water and land resources in the Shiyang River basin,which showed that the analysis result of the aberrance point was reliable.Thus it could be seen that since later 1970s,the natural conditions have not been the main factor that influences the change of runoff in the downstream of Shiyang River,and human activities in the upper and middle reaches have produced a dominant effect on the runoff. |