STAGE AND INHOMOGENEITY OF RUNOFF INFLUENCED BY PRECIPITATION ON HONGNENCHUAN BASIN IN MIYUN COUNTY

With the purpose of studying the hydrological-ecological changing process and helping the further statistical analysis of Miyun county in Beijing,this paper focus on collecting the data of water precipitation and runoff of Hongmenchuan Basin from 1990 to 2006.The results showed that the average annual precipitation of the target is about 600 mm per year and relatively less than others.From 1990 to 2000,the precipitation of the area gradually deCreased.The annual variation of Runoff fluctuated intensely from 1990 to 2006 and deCreased significantly.The average annual runoff of the target is 16090000 m3 and mainly distributes from June to September.Besides above,the periodity of inter-annual runoff appears obviously.Runoff is rich(runoff coefficient=0.39) in 1990～1998,but it occurred much more less(runoff coefficient=0.09) thereafter.As to the annual distribution of runoff,the annual inhomogeneity in 1990-1998 is comparatively less while in 1998-2006 is comparatively more.