Soil Erosion Simulation In Hilly Area Of South China

The Soil and Water Assessment Tool (SWAT model) uses MUSLE (Modified Universal soil loss equation) calculate sediments yield based on Hydrologic Response Units (HRU), slope-length is one of very important parameters in MUSLE. Given that the SWAT model have some defect to compute the average slope-length of HRU, in this paper, the Xixi Watershed, Jinjiang basin was taken as the study area. According to the terrain characteristics in hilly area of south china which has a larger fluctuation of slope changes, using the Arc View GIS SWAT slope-length auto modified module calculates HRU average slope-length, carried out its applicability research and accuracy improvement analysis of sediments yield simulation in hilly area of south china. The result obtained in this study show that Slope-length auto modified module could compensate somewhat for the deviation of calculating the slope-length of HRU when applying the SWAT model to the mountainous and hilly land watersheds. For this reason, the Slope-length auto modified module should be use for accurate simulation of sediment yield when using the SWAT model in the hilly area of southern part in China.Collapse hill is a special erosion physiognomy type distributed in red hilly region of south China. Through the proper subwatershed delineation method, make a distinction between collapse hill erosion subwatershed and none collapse hill erosion subwatershed calibrate the model parameters, and established the sediments yield model for collapse hill erosion watershed based on SWAT model; Therefore, the model provides a technical support and theoretical basis for quantitative research and soil and water conservation effect quantitative evaluation in collapse hill erosion area. The different revegetation scenarios were simulated Based on this SWAT model in order to evaluate the impact of vegetation changes on sediments yield. The results demonstrate that revegetation has a great impact on the sediment yield in collapse hill erosion area. Compared with the orchard rehabilitation and agricultural land, the forest rehabilitation and high covering grass can reduce sediment yield effectively in collapse hill erosion subwatershed.