Research On The Calculation And Control Of Soil Erosion In Xingshan County

Soil erosion has become an environmental problem that cannot be ignored in China,affecting human production and living activities.Xingshan County is located in the mountainous area,the karst landform is developed,and the risk of soil erosion is high.The calculation and control research on soil erosion is beneficial to maintaining regional ecological security and promoting the coordinated development of social economy and natural environment.Based on the theoretical basis of the Universal Soil Loss Equation(USLE model),this paper selects factors such as rainfall erosivity,soil erodibility,topography(including slope and slope length),vegetation cover and soil and water conservation measures in Xingshan County.Obtaining factor data with the support of technologies such as GIS and basic data such as statistical yearbooks:calculating rainfall erosivity based on monthly rainfall;using EPIC model to calculate soil erodibility factor;obtaining topographic factors based on DEM data and two-dimensional surface calculation;using human-computer interaction method to interpret remote sensing images can obtain land use layer,by which experience values can be assigned to vegetation cover and soil and water conservation measures.The soil erosion data in Xingshan County is calculated in the In VEST software.After measuring,the total area of soil erosion in Xingshan County is 48671 hectares,accounting for 21% of the total land area of Xingshan County,the intensity of loss is mainly mild and moderate.The small watershed with large erosion intensity is mainly distributed in the midwest of Xingshan County.Soil erosion mainly exists in arable land,garden and other fields where human activities are more frequent,at the same time,it is concentrated on the area between 15°～25°.According to the space,land use and slope characteristics of the loss distribution,the key problems of Xingshan County were identified,including slope loss,channel erosion,geological disasters,non-point source pollution and the water-level fluctuation zone of the Three Gorges Reservoir Area.Combined with the natural environment,social economy,land use status,current status of soil erosion,and basic functions of soil and water conservation in Xingshan County,14 indicators are selected to construct a regional indicator system for soil and water conservation.Then standardize the raw data for the indicator factors through standard deviation standardization.Using SPSS principal component analysis method to extract the principal components and the weight is determined according to its contribution rate.Initial partitions can be generated by cluster analysis on principal component composite scores,after the adjustment and merger,Xingshan County is finally divided into six soil and water conservation type zones.From the perspectives of regional scope,natural environment characteristics,and current situation of soil erosion,various types of districts are analyzed,and soil and water conservation control rules are formulated according to local conditions.In order to further clarify the layout direction of soil erosion control projects in the future,identifying key areas of soil erosion,including key prevention areas and key controlled areas.Comprehensive consideration of soil erosion intensity,forest coverage rate and other quantitative conditions and ecological function red line area,drinking water source protection area,nature reserves,scenic spots and other qualitative conditions,identifying key prevention areas.Adjustment and merging of the initial partition according to the principle of centralized contiguous and multi-regulation,dividing out the key prevention area of soil erosion at the county level in Daba Mountain,accounting for 17.89% of the total land area of Xingshan County.By analyzing the small watershed range,natural environment and soil erosion characteristics of the prevention area,control measures which focus on prevention and giving priority to protection can be formulated.Comprehensive consideration of soil erosion intensity,sloping land occupation ratio and other quantitative conditions and geological disaster-prone areas,large tailings area,rocky desertification karst area and other qualitative conditions,identifying key controlled areas.Adjustment and merging of the initial partition according to the principle of centralized contiguous and prevention zone priority,dividing out the key controlled areas of soil erosion at the county level along the Xiangxi River、the key controlled areas of soil erosion at the county level in eastern county,and the area percentage of them are 21.01% and 11.07%.By analyzing the small watershed range,natural environment and soil erosion characteristics of the two key controlled areas,comprehensive control measures which focus on soil erosion and ecological environment restoration can be formulated.