[Objective] Effects of rainfall intensity and slope gradient on erosion process were studied in red soil hillslopes

to provide a scientific basis for soil and water loss control. [Methods] An simulated rainfall experiment was conducted to quantify the effects of rainfall intensity (240

180

120

60 mm/h) and slope gradients (25°

15°

5°) on runoff generation and sediment yielding on red soil slope. [Results] (1) In same slope gradient

the accumulative runoff and accumulative sediment load both significantly and linearly increased with the increase of rainfall intensity. In same rainfall intensity

slope runoff increased with slope gradient increasing

but sediment transport exhibited an elusory variaton. (2) The soil loss increased when rainfall intensity increased from 60 to 180 mm/h

while there was a critical slope at 15° in the rainfall intensity of 240 mm/h

wherein the soil loss increased at first and then decreased. Runoff rate kept a relatively stable stage after an initial fluctuated increased from 0 to 15 min

this fluctuation phenomenon was obvious under rainfall intensity of the 240 and 180 mm/h. The sediment generation rate rapidly increased and then decreased quickly. This pattern was more pronounced when there were heavy rains and steep slopes. (3) The average flow velocity of slope flow had a significant fitting relationship of power function with the unit width discharge and slope ratio. The flow rate experienced a similar regular pattern with respect to surface runoff and sediment generation. [Conclusion] Rainfall intensity is the main factor in the red soil erosion process

and velocity could be used as important indicators to assess red soil slope erosion features.