Response Of Soil Erosion Based On Fractal Characteristics Of Vegetation Pattern And Application Research

This paper applies landscape ecology,hydrology,soil erosion,fractal theory,mathematical statistics and other disciplines,and adopts a research method of combining numerical simulation with theoretical analysis in combination with GIS and RS technologies,to carry out response of soil erosion based on fractal characteristics of vegetation pattern and application research,construct a digital vegetation model with basin pixel scale grid structure based on NDVI vegetation index,propose a calculation method of basin NDVI vegetation index and vegetation pattern FBM fractal dimension based on moving window method,illustrate the spatial distribution characteristic of Dali River Basin NDVI vegetation index,reveal the inter-annual variation,spatial distribution,vertical distribution characteristics and variation laws of vegetation pattern FBM fractal dimension with different spatial scales in Dali River Basin,construct a sediment yield multiple linear regression model of Dali River Basin,comparatively study the advantages and disadvantages of the vegetation pattern FBM fractal dimension and NDVI vegetation index in the aspect of comprehensive quantitative basin vegetation parameters,initially apply the vegetation pattern FBM fractal dimension to the soil and water conservation in West-East Natural Gas Transmission(second-line)Project,put forward a calculation method of vegetation pattern FBM fractal dimension of the production and construction project before and after soil and water conservation by using the aerial remote sensing images with UAV high resolution as basic information source,so as to provide a certain theoretical support for the comprehensive quantization of basin vegetation cover spatial distribution characteristics,construction of basin erosion and sediment yield prediction model as well as reasonable basin soil and water conservation plan,soil and water conservation monitoring and control effect evaluation of production and construction project.The main conclusions of this paper are as follows:(1)The research results of spatial distribution characteristics of NDVI vegetation index in Dali River Basin show that,the normalized NDVI value of Dali River Basin is 0.221;the normalized NDVI value of Dali River Basin from upstream to downstream is increased,respectively 0.193,0.214 and 0.259.The normalized NDVI value of 14 small basins of Dali River Basin with area of between 179.4?392.5 km2 is between 0.155?0.268;the normalized NDVI value of 53 small basins of Dali River Basin with area of between 21.9?208.9 km2 is between 0.133?0.287.In the basins of different spatial scales,the proportion of pixels with NDVI value within 0.1?0.3 in the total pixels is 59?90%;the size of normalized NDVI is mainly controlled by the number of pixels with pixel NDVI value of less than 0.1 and greater than 0.3;the normalized NDVI value decreases in the form of power function with the increase in the proportion of pixel NDVI value of less than 0.1,and increases in the form of power function with the increase in the proportion of pixel NDVI value of greater than 0.3.The increasing range of pixels of different NDVI values decreases with the increase in basin area.(2)The research results of spatial-temporal change characteristics of vegetation pattern FBM fractal dimension with different spatial scales in Dali River Basin show that,the vegetation pattern of the basin has self-similarity spatial distribution characteristic,which can be represented by FBM fractal dimension;the vegetation pattern FBM fractal dimension of entire basin of Dali River is 2.817;the vegetation pattern FBM fractal dimensions in upstream,midstream and downstream of Dali River Basin are respectively 2.810,2.814,2.816.The vegetation pattern FBM fractal dimension of 14 small basins of Dali River Basin with area of between 179.4?396.5 km2 is between 2.773?2.814;the vegetation pattern FBM fractal dimension of 53 small basins of Dali River Basin with area of between 21.9?208.9 km2 is between 2.695?2.811;the vegetation pattern FBM fractal dimension increases in the form of power function with the increase in the basin area,but the increasing range is smaller and smaller.When the basin area exceeds a certain value,the vegetation pattern FBM fractal dimension tends to be stable,and infinitely close to the fractal dimension of the entire basin.Driven by changes in soil and water conservation measures in the basin,from 1990 to 2006,the vegetation pattern FBM fractal dimension of each sub-basin in Dali River Basin increased first and then decreased.The inter-annual variation,spatial distribution,vertical distribution characteristics and variation laws of the vegetation cover characteristics and vegetation landscape pattern are studied;and the vegetation dynamic variation law of Dali River Basin in recent years is analyzed.The vegetation pattern fractal dimension gradually decreases from downstream to upstream with the increase in the distance from the exit point;the vegetation pattern tends to be complex and broken from downstream to upstream.Characteristics of the vegetation pattern fractal dimension and spatial-temporal change characteristics at different scales are analyzed.(3)Different NDVI value increases the number of pixels,amplitude decreases with increase of the basin area,shows that with the increase of area,like yuan number per unit area on the decrease.On different NDVI value per unit area on the number of pixels,and vegetation pattern FBM fractal dimension between the trend of decreasing,the correlation coefficient is 0.663(p<0.01).Vegetation characteristics of Dali river basin is studied and the spatial and temporal variation characteristics of vegetation landscape pattern,analyzes the Dali river basin in recent years,the vegetation dynamic change rule.(4)Vegetation pattern FBM fractal dimension is studied and the relationship between the elevation height,the results showed that the vegetation pattern FBM fractal dimension values present a tendency of decrease with the increase of altitude and low altitude area vegetation landscape fractal dimension is 2.847,the biggest followed by 2.833,2.826,high altitude,low altitude and high altitude area minimum 2.809.(5)According to 38 flood seasons of storm floods,runoff and sediment data in Caoping Station,Qingyangcha Station and Lijiahe Station of Dali River,sediment yield multiple linear regression model of Dali River Basin is established by mathematical statistics method by using rainfall erosion factor(i.e.runoff erosion power),topography factor(i.e.topographical feature FBM fractal dimension),vegetation cover factor(NDVI vegetation index)or vegetation pattern factor(i.e.vegetation pattern fractal dimension)as main impact factors;the results show that in the basin using the vegetation pattern FBM fractal dimension as surface vegetation cover quantitative factor,the simulation precision of the sediment yield multiple linear regression model is higher;gray correlation analysis results show that,compared with the normalized NDVI vegetation index of the basin,the vegetation pattern FBM fractal dimension more comprehensively and accurately reflects the relationship between underlying surface vegetation characteristic and soil erosion.Therefore,in the selection of comprehensive quantitative parameters of basin vegetation,the vegetation pattern FBM fractal dimension is better than that of NDVI vegetation index.(6)Based on GIS technology,illustrates the topographic factor of soil erosion intensity and the basin of Dali River Basin and sub basin(including gully density,slope and terrain)spatial distribution characteristics;partial correlation analysis was used to calculate the intensity of soil erosion and vegetation pattern FBM correlation coefficient between the fractal dimensions of-0.712;correlation analysis method between the calculated slope,gully density,roughness and fractal dimension of vegetation pattern and soil erosion intensity using grey correlation were 0.702,0.701,0.705 and 0.706.Construction of the vegetation pattern fractal dimension,slope,gully density,undulating terrain parameters for the soil erosion intensity of the multivariate linear regression model using SPSS statistical analysis software;using cluster analysis of 53 small watershed of Dali river basin is divided into Small Watershed Governance and key management of small watershed in 2 categories,and soil keep the initial Countermeasures on Dali River Basin 24 small watershed management.(7)Vegetation pattern FBM fractal dimension with different spatial scales in Dali River the NDVI vegetation index and vegetation pattern FBM fractal dimension of each key monitoring section before and after the construction are calculated by using the remote sensing images of three key remote sensing monitoring sections of soil and water conservation in West-East Natural Gas Transmission(second-line)Project as basic information source;comparative analysis results show that the NDVI vegetation index and vegetation pattern FBM fractal dimension after the construction of key remote sensing monitoring sections of soil and water conservation in West-East Natural Gas Transmission(second-line)Project are less than the corresponding value before the construction;therefore,in soil and water conservation monitoring of production and construction project,the vegetation pattern FBM fractal dimension can be regarded as the comprehensive quantitative indicator which reflects the disturbance and damage of surface vegetation caused by construction;the NDVI vegetation index and vegetation pattern FBM fractal dimension before and after soil and water conservation in waste disposal area and pipeline operation zone of production and construction project are calculated by using aerial remote sensing images with UAV high resolution as basic information source;the research results show that:in soil and water conservation control effect evaluation index system of production and construction project,the vegetation pattern FBM fractal dimension can be regarded as the comprehensive quantitative indicator of vegetation restoration.