Preliminary study on the characteristics of annual precipitation and runoff in Longjiang catchment

The serial characteristics of precipitation and runoff in Longjiang catchment have been analyzed based on the gauge records of runoff and annual precipitation between 1959—2000.Indexes of unevenness and concentration were calculated for runoff and precipitation annual distribution.By analysis,the conclusions is that the changing trend of runoff was similar to that of precipitation in long period.A cycle period from 8 to 11years was found both in runoff and precipitation,which in runoff was more obviously;Due to the impacts of runoff-supplying source,47.5% of the annual total runoff occurred in summer.Runoff annual distribution was evener than that of precipitation.Precipitation distribution centralized in July,and runoff in August,about 1month lags to precipitation;The changing of runoff was caused primarily by precipitation,but the seasonal changes in ground water and evaporation would have also obviously effect on the river regimes in winter and spring.