[Obejective] The variation of runoff in the Tuotuo River in the headwaters of the Yangtze River in the past 51 years under different time scales of precipitation

such as interannual

interdecadal and season

and also the lagging effect of runoff on precipitation were analyzed in order to provide a theoretical basis for the management and utilization of water resources in the basin.[Methods] This paper used the runoff and precipitation data of hydrological station and the meteorological station in Tuotuo River of the Yangtze River source region from 1961 to 2011

and combined the statistical methods such as cumulative anomaly

variation coefficient

concentration frequency and concentration period

to investigate the variations of runoff and precipitation at decadal

annual and seasonal time scales. The hysteresis effect of runoff to precipitation was also discussed.[Results] The annual and seasonal runoff of the Tuotuo River Basin in the past 51 years showed an increasing trend. The annual

spring and summer runoff increased significantly. The climatic tendency rates were 1.00×108 m3/10 a

6.00×106 m3/10 a

6.30×107 m3/10 a

respectively. The runoff of the river was mainly concentrated in the period from May to October

especially from late July to mid-August. There was a significant correlation between runoff and precipitation. The runoff had a lagging effect on precipitation in most years

and the average lag time was about 10 d. The hysteresis period was observed being increased over the past time.[Conclusion] In the past 51 years

the trend of runoff and precipitation in the study area had increased

and the lag effect of runoff on precipitation was about 10 days.