In order to research the impact of rainfall intensity on slope erosion process and distribution of sediment particles in the rocky mountain area of North China

two typical soils from this area were selected

and the variation of runoff

the composition of particles and the enrichment rate of particles in erosion sediment were analyzed under 4 different rainfall intensities (30

60

90

and 120 mm/h) through rainfall simulation experiments in laboratory. The results were as follows: (1) With the rainfall intensity increased from 30 mm/h to 120 mm/h

the time producing runoff decreased by 79% and 85% for the loess cinnamon soil and calcic cinnamon soil

respectively; (2) Under the 60

90

and 120 mm/h rainfall intensity

runoff intensity and sediment concentration of the loess cinnamon soil decreased first and then increased with rainfall time extending

and then tended to be stable

while runoff intensity and sediment concentration of calcic cinnamon soil appeared similar trend only under 120 mm/h rainfall intensity; (3) When the rainfall intensity increased from 30 mm/h to 120 mm/h

the content of coarse particle increased in the lost sediment for the loess cinnamon soil

and the contents of sand and coarse silt increased by 67% and 16%

respectively. However

there was no obviously change for the calcic cinnamon soil; (4) In the initial stage of rainfall

the clay and fine silt enriched obviously

and the coarse silt and sand were not easy to be lost

while with the extending of rainfall the enrichment rate of different sediment particles gradually approached to 1

especially under heavy rain.