To study the characteristics and hydrological dynamics of rainfall runoff on sloping land

the overland flow and subsurface flow on the weathering granite sloping land at different rainfall intensities (30

60

90

120

150 mm/h) and slope gradients (5°

8°

15°

25°) were comparatively studied with the method of artificial simulated rainfall. The results showed that the initial starting time of both the overland flow and subsurface flow advanced with the increase of rainfall intensity and slope gradient. The initial starting time of subsurface flow obviously lagged behind that of overland flow. With extension of rainfall time

the subsurface flow rate at different slope gradients turned to be stable after an increasing trend. The greater the rainfall intensity was

the earlier the subsurface flow rate reached the peak. And subsurface flow rate began to run down after the rainfall stopped for some time. In most cases

the proportion of subsurface flow was larger than that of the overland flow. The proportion of overland flow increased with the growth of rainfall intensity. Slope gradient

however

had little influence on the proportion of overland flow. The runoff correlation between the overland flow and rainfall intensity was relatively large

and the runoff coefficient of subsurface flow was mainly affected by slope gradient. The runoff modulus of overland flow

subsurface flow and mixed flow (overland flow and subsurface flow occurred simultaneously) showed a strong positive correlation with rainfall intensity and displayed the following order: mixed flow＞subsurface flow＞overland flow.