Based on the runoff data during the period between 1962and 2008

runoff variations in the Jihe river watershed(1019km2)

located in the third sub-region of the Loess Plateau

were characterized using statistical analysis.The results indicate that the runoff presented a evident decreasing trend during the research period

and the runoff in the 1970s

1980s

1990sand 2000saccounted for 62.3%

61.1%

30.2% and 35.2% of the 1960srespectively

with an annual increasing rate of-2.7%and and a variation coefficient of 0.75.It was observed that inter-annual distribution of runoff was greatly unsteady

and the runoff percentages in flood seasons ranged from 50.8%to 95.2% with an average of 76.5%and a monthly variation coefficient of 1.13.According to wet and drought year classification of the runoff

Jihe river watershed has gone since the 1960s through the periods of wet year

average year

sub-wet year and drought year

respectively.The runoff decreased dramatically after 1990

lasting a nine-year period of drought

in coincidence with the large-scaled implementation of soil and water conservation.Thorough descriptions of the response of hydrological factors to land use and cover changes are another requirement for future study in the watershed.