Rocky Desertification Land Soil Erosion Processes In The Northern Part Of Guangdong Artificial Rainfall Simulation Study

North Guangdong mountain-area is an entironment-vulnerable karst area in themiddle subtropical zone of South China, where rocky desertification process isprominent and the problem of rocky desertification is rather serious.Some scientific problems such as the reasons, the process and the reversionmechanism of rocky desertification have been researched through qualitative analysis,but microscopic process and mechanism study is scarce. In order to complete the task,Simulated rainfall experiments are completed on 3 different lands in typicalrocky desertification slope in North of Guangdong Province.(1) From the results: it is found that the runoff processes in different lands havethe characteristics of rapidly rise and fall and big range of the variety. The relationbetween the rainfall intensity and steady surface runoff is distinctly linearity. Theirregression equations are blow: R=0.7471P-0.1244, R=0.5369P-0.0938, R=0.4850P-0.0754. Runoff coefficient is mainly influenced by rainfall intensity. Therelation between the rainfall intensity and the time of flow initiating is shown to beexponential. The regression equations are blow: T=3.82P^-1.20,T=2.55P^-1.29,T=1.80P^-1.17. The effect of land surface condition on runoff process diminishes withrainfall intensity enlarged. The steady infiltration rate of the experimental area isdecided by the characteristics of the land surface, and it is irrelevant with rainfallintensity and rainfall time. Under the same land surface condition, the sediment yieldfluctuated descends carrying on the process of run and ascends as rising of rainfallintensity. The relationship between sediment and runoff intensity shows to beextremely remarkable linear correlation。(2) Seldom of the rainfall which arrive the surface stability exchanged the soilwater. The runoff and Groundwater replenishment enlarges with rainfall intensityenlarged. With rainfall intensity enlarged, the proportion of runoff occupied rainfall isenlarging but that of the groundwater occupied rainfall is reducing. The relationbetween rainfall and runoff is distinctly linearity. The regression equation likes blow:R=-3.2208+0.5796P r²=0.8558. The runoff model of typical rocky desertification slope is including excess infiltration runoff model and saturation runoff model.(3) Under the same land surface condition, the sediment yield fluctuateddescends carrying on the process of run and ascends as enlarging of rainfall intensity.The relationship between sediment yield and runoff intensity shows to be extremelydistinctly linear correlation。Whether under rainfall intensity, the sediment yield ofbare land is more than the grass land and artificial land. The land cover has theimportant inhibitory action to sediment yield, especially under the big rainfallintensity condition. The contour ditch farming can reduce sediment yield under smallrainfall intensity, but the influence reduce with the rising of rainfall intensity.