The simulated rainfall method was applied

and three rainfall intensities (60

90 and 120 mm/h) of representative erosive rainfall and three common slope gradients (3°

5° and 7°) were chosen in the black soil region to analyze the effects of rainfall intensities and slope gradients on runoff

soil erosion

runoff rates and sediment concentrations of farmland unpaved road. The results showed that the total runoff mainly varied between 56.3 and 61.8 mm for different treatments. However

soil erosion rates increased 1.8～11.0 and 1.2～10.0 times

respectively with increasing rainfall intensities and slope gradients. Additionally

the mixed impacts of rainfall intensity and slope gradient on soil erosion were greater than those of the individual impact of the influencing factors. There was a mutual stimulation among the factors upon soil erosion. Furthermore

the effects of rainfall intensities on runoff rate patterns were obvious

while the effects of slope gradients were small. As rainfall intensities and slope gradients were increased

sediment concentrations obviously increased

and the fluctuation ranges also strengthened. Therefore

rainfall intensity and slope gradient showed notable effects on soil erosion of farmland unpaved road in the black soil region

and controlling rainfall and runoff erosivity

or changing pavement characteristics could effectively prevent soil and water loss on hillslopes.