Three runoff plots of bare land

waste grassland and shrub land were established in Yangou watershed of Yan'an City.Based on observations of total rainfall

rainfall duration

runoff depth

sediment yield

infiltration rate in individual rainfall events

the erosion characteristics of each plot were investigated using the statistic package of SAS.The results indicate that regardless of rainfall intensity

both runoff and sediment yields decreased

and correspondingly the infiltration rate increased in the three plots as listed in order.Runoff were closely correlated with rainfall.Sediment yields increased with total rainfall

especially in the bare-land plot.Similarly

the infiltration rates increased with total rainfall amounts

but decreased significantly in rainfalls with high intensity.The sediment yields correlated well with the runoff.However

a quadratic function performed better in describing the relationship between the sediment yield and runoff of the grassland.