| Maintaining and improving the ecosystem service function is the cornerstone and difficulty in coordinating the contradiction between ecological environment protection and social economic development.As an important ecosystem service function,reasonable zoning of water conservation functions,and targeted protection and governance objectives and measures,can provide reference and basis for regional water resources allocation decision-making and ecological protection planning.which can provide reference and basis for regional water resources allocation decision-making and ecological protection planning.Taking the Nansi Lake Basin as an example,this thesis carries out value correction calculation and spatial heterogeneity analysis on water conservation function based on topographical perspective and social perspective.Using Pearson correlation analysis and PCA principal component analysis method,the influencing factors of water conservation value were studied from two different scales in the Nansi Lake Basin and its sub-basin Baimahe Basin.The influencing factors above the medium correlation level were selected to construct a comprehensive assessment model for water conservation,and the water source conservation function was divided according to the status of water conservation function.The paper obtained the following results:(1)After the terrain correction,the total value of water conservation in various types of land has decreased.The decline is in the order of cultivated land>grassland>forest land>construction land.The change of water conservation value in each municipal administrative region is different after social amendment,the regional value of the higher degree of socio-economic development has increased,and vice versa.After being corrected by two perspectives,water conservation value of the Nansi Lake Basin decreased from 16.78×10~8 yuan to 13.04×10~8 yuan,a decrease of 22.29%.The revised value of water conservation tends to be south high and low north,east high and low west.(2)Pearson correlation analysis was used to analyze the correlation of 13influential factors,and the factors above the moderate correlation were extracted for PCA principal component analysis.The main factors affecting the Nansi Lake Basin from the largest to the smallest,including seven positive factors related to evapotranspiration,rainfall,NDVI,surface water resources,GDP,urbanization rate,and crop planting area and three negative correlation factors:urbanization intensity,land fragmentation degree and population aggregation coefficient.The main factors affecting the Baimahe Basin are four positive correlation factors:rainfall,evapotranspiration,NDVI,population aggregation coefficient,and four negative correlation factors:urbanization intensity,land fragmentation,urbanization rate and surface water resources.(3)The comprehensive evaluation model of water conservation is constructed by selecting the influencing factors above the medium correlation level.The indicators are normalized according to the statistical results of the county area,and the weights are determined according to the comprehensive influence degree of each influencing factor.Comprehensive consideration of the critical value of the confidence interval of the water source conservation function in the cold hot spot area,the Nansi Lake Basin is divided into key protection areas,sub-key protection areas,improvement and improvement areas,comprehensive treatment areas and basic prevention areas.The Baimahe Basin is divided into four functional areas:key protected areas,sub-key protected areas,improvement and improvement areas,and comprehensive treatment areas.The analysis of the zoning results shows that in the large-scale basin,natural factors such as climate and vegetation cover have greater impact on the water conservation function of the basin.In small-scale watersheds,human disturbances such as population aggregation and urban construction will have a more significant impact on water conservation functions in the basin. |
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