Experimental Study on Process of Rainfall-Infiltration-Runoff Generation on Rocky Desertification Slope in North of Guangdong Province

Simulated rain is a valid tool to examine soil erosion on sloping land.Experiments under 36 events of simulated rainfall with intensities of 0.3 mm/min,0.48 mm/min,0.72 mm/min and 1.08 mm/min and different duration were carried out on three different types of lands(bare land,grassland and farmland) in typical rocky desertification land slope in northern Guangdong Province.Results show that the runoff processes in different lands have features with the fluctuating nature of the valley and peak due to rock heterogeneity factors.The fluctuation range of initial runoff curve was large.There is a very clear linear relationship between reaching stable surface runoff intensity between the rainfall intensity.Land surface runoff intensites on three kinds of land use types increase with the rise of rainfall intensity.The largest and significant increment of runoff occurs on bare land.Although the infiltration rate also increases with the rise of rainfall intensity,the increment is significantly less than that of runoff;the least increment is observed on bare land,however,the infiltaration basically remains stable.Under the case of less initial soil moisture,the time of flow production rapidly shortens with increase of the rainfall intensity;there is an obvious power function relation between initial soil moisture and rainfall intensity.Surface runoff on three types of land produces when the rainfall amount meets a certain level.