Taking the Chaohe River Basin above the Miyun Reservoir as a study area

the influence of soil and water conservation measures on annual runoff was assessed quantitatively by the rainfall-soil and water conservation-runoff statistical model established on the basis of multiple regression analysis using historical annual runoff

annual precipitation and areas of soil and water conservation measures in the drainage basin during 1961-2005.The results showed that during 1961-1970

1971-1980

1981-1990

1991-2000 and 2001-2005

the average annual runoff-reduction effects were 2.54%

3.52%

28.71%

6.87% and 48.02%

respectively

with an average of 22.96% during 1981-2005.The average annual runof-freduction effect was the greatest during 2001-2005

intermediate during 1981-1990

and the smallest during 1991-2000.The runoff reduction effects of soil and water conservation measures were more profound in the drier period.