A Study on the Quantification of Annual Runoff Distribution Characteristics in the Dagujia River Basin

Manne-Kendall and minimum variance methods were applied to analyze the average value change-point of the runoff data in Dagujia River basin from 1966 to 2004,based on this results,the runoff was divided into four periods.And then the change of annual runoff distribution in Dagujia River basin was discussed by using the index of unevenness,degree and time concentration,and variation range etc.The results showed that:（1） The annual runoff distribution in Dagujia River was very uneventful,the runoff mainly concentrated in Jun to Oct.（2） The annual runoff distribution during 1966～1971 was very similar to that of 1982～1996,and the 1972～1981 was almost similar to 1997～2004.（3） The annual runoff distribution has changed a lot during 1997～2004,which caused more difficulty in exploiting and using the water resource.