| The earth is the material base of human survival.Soil erosion has been a globally ecological issue,severely effecting the sustainable development of regions and the social security and stabilization.This problem has raised worldwide attention.Danjiangkou reservoir area is the water resource of the South-to-North Water Transfer Project and soil erosion directly relates the ecologically environmental quality of the reservoir area and the social efficiency of the project.This paper bases on platforms GIS and RS,researches into Danjiangkou reservoir area,and calculates the amount of soil erosion in 2002,2006 and 2010 with revised universal soil losing erosion(RUSLE),and finally generates the distribution map of soil erosion.With that basis,this paper also researches quantitatively on the scale effect,spatial and temporal fractionation characteristics and driving force,providing scientific evidence for improving soil erosion in Danjiangkou reservoir.The main works and conclusions are following.(1)Landscape metrics are used to research the spatial scale effect of soil erosion intensity level map in Danjiangkou reservoir,and the model to select the optimum scale based on information entropy and fractal theory is developed.The result of this model is verified by scale effect curves of landscape metrics.The results show that there exists dependence between the landscape metrics of soil erosion patches and scale,and separate metrics respond differently to scale.The scale effect of some landscape metrics is predictable with simple functions,and the scale effect of others is only predictable within a certain scale range but irregular beyond such range.The optimum scale is determined as 90 meters according to the selecting model,which has been proved reasonable by observing 90-meter is in the first scale area of the curve using scale effect curves of landscape metrics method.(2)The spatial and temporal distribution characteristics in Danjiangkou reservoir in 2002,2006 and 2010 is analyzed under the optimum scale.On the temporal development,the extent of soil erosion decreases with time passing and then centroid of erosion with light intensity moves southwards.On the spatial distribution,soil erosion with minor and light intensity mainly exists in the reservoir area,while erosion with middle or more intensive intensity is observed more often in the northern mountain area.The order of soil erosion intensity in different categories of land utilization is,unused land,construction land,farmland,forest land,water.In terms of slope angle,it is observed that soil erosion on slopes at slope angles between 15 and 25 degrees is most severe.(3)The relationship between soil erosion intensity and main driving force including waterfall,land use intensity,and slope is quantitatively researched by geographically weighted regression(GWR)and grey correlation analysis in Danjiangkou reservoir in 2002.It has been shown in GWR model results that there is no obvious linear relationship between these three elements and soil erosion intensity,with R~2(Adjusted)only 0.38.Slope is the primary element in the most area,while waterfall is the leading element in northern area.It is interpreted in the grey correlation analysis that the order of correlation between these three elements and soil erosion intensity is slope angle,waterfall,land utilization intensity.This paper proposes some reasonable suggestions for improving management of soil erosion based on driving force researches. |
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