Study On Risk Pattern Of Water Loss And Soil Erosion Based On RUSLE And MCR

Base on the DEM data, rainfall records, and structural data of soil in Diebu County, Gansu Province, this research integrated two models, Revised Universal Soil Loss Equation (RUSLE) and Minimum Cumulative Resistance (MCR), in the analysis to the risk pattern of water loss and soil erosion in the aspect of SPs. The main content of this research included:calculated present risk pattern of soil erosion by comprehensive analyzing of each factors in the equation, classified the soil erosion situation in the risk pattern and analyzed its distribution rule, assessed the potential risk of further erosion in the target area, and it finally came to certain protection methods. The conclusions were as follows:(1) according to the calculation result to RUSLE model in the research area, the estimated average soil loss in tons per acre per year A in Diebu County relied among 0-3287.39 (t·hm-2·a-1), and it was classified as low erosion in Gansu Province; (2) each factor in RUSLE model here could be defined from low to high as I-V five classes based on its erosion sensitivity, and if the resistance of each class was defined as 100,10,1,0.1 and 0.01, the software of ArcGIS could gain a picture of soil erosion risk pattern whose form was similar to the ecological security pattern of species protection, in which the areas of lower security class were surrounded by those of higher class and appeared radial arranged; (3) the fragmentation of each part in the risk pattern was much higher, which was in accordance with the characteristic of Loess Plateau in China, and it had a significant influence on the pattern and function of local landscape-ecological system; (4) in the soil erosion risk pattern of Diebu County, the amount of soil loss increased with the surface runoff, but inversely with the fragmentation of soil erosion areas, and the reduction of soil loss could decrease the possibility of occurrence to debris flow and landslide, therefore degrade the soil erosion in reverse; (5) among all the factors related to RUSLE model, it was difficult to alternate R (rainfall-runoff erosivity factor)and K (soil erodibility factor)because they were mainly determined by natural dynamic and the economic situation of Diebu County could not afford such an alternation, however, the factors of LS, C and P were relatively changeable by manpower, and it had been improved in the past decade as a positive result of the Natural Forest Protection Project, so whenever the methods of water and soil conservation, such as the transformation of planting mode and improvement of vegetation coverage, was needed, these factors could be considered to be the most available access to solve problems, and we suggested that the choosing of method should be accordance with the realistic situation.