USLE is a better and widely used model for forecasting soil erosion.Rainfall erosivity and its distribution characteristics is the key to the application of USLE in soil erosion research in a large area.Based on the daily rainfall erosivity model

the average monthly and annual rainfall erosivity model for the Loess Plateau is established.Using the daily rainfall data from 235 weather stations from 1971 to 2000 on the Loess Plateau

we estimated the monthly rainfall erosivity and the annual rainfall erosivity

which were used to interpolate a spatial distribution map by the Kriging interpolation method.The spatial pattern of rainfall erosivity was also analyzed for different topographic regions.Results show that there is a descending trend from southeast to northwest in spatial pattern of rainfall erosivity on the Loess Plateau.Rainfall erosivity on the Loess Plateau is between 300 and 7 500

with an averaged value of less than 3 000.The topographic units

from large to small

are rock mountainous area

hilly gully area(Yan'an)

high plateau gully area

hilly gully area(Yulin)

and hilly gully area(Longxi).Rainfall erosivity is mainly concentrated in July and August.Cycle analysis indicates that there is a 2.7-year undulating period of rainfall erosivity in the entire region and the undulating range of rainfall erosivity is more than twice of annual average value.There are distinct differences among different regions.