Assessment and Spatial Distribution of Soil Erosion in Sichuan Province

Sichuan Province is located in the upper reaches of the Yangtze River.The quality of its ecological environment not only has a direct bearing on the regional ecological security,but also it occupies a pivotal position in the ecological environment and the sustainable development of social economy of the upper reaches of the Yangtze River.And yet soil erosion of this region has become the most serious ecological problem.In this paper by using the technique of GIS,analysis was made of the impact of rainfall factor,soil factor,topography factor and vegetation coverage on soil erosion sensitivity based on universal soil erosion equation.On this basis of overlapping operations of the single factor,thus an evaluation was gotten on soil erosion sensitivity of the study area by applying the spatial overlapping analysis functions of ArcGIS;Discussion was made on the soil erosion sensitivity space dividing rule of different terrain features effected by different leading factors.The results showed that the soil erosion sensitivity of the study area was mainly based on the high,middle and extreme sensitivity,the mild sensitivity and insensitivity constituted a relatively minor proportion,the spatial distribution regularity of soil erosion sensibility was obvi-ous;The area was separated by the Longmen Mountains in the center of Sichuan province and the middle reaches of the Yalong River in southwest of Sichuan province,the sensitivity of most parts of the western area was moderate and low,the most parts of the eastern area were high and extreme sensitive areas.It indicated that the degree of soil erosion sensitivity coincided with the existing overall distribution;Rainfall,soil texture,topographic,vegetation coverage and other natural factors were potential conditions of occurrence and development of soil erosion,vegetation converage in the study area was affected by human activity more significantly than other factors.Therefore,when it was extremely difficult to change its natrual factors,protection of the exsiting primeval forest vegetation in study area and adequate restoration of ecosystem had important implications for soil erosion control.