Water, Soil Conservation Effect And Soil Erosion Models During The Ecosystem Rehabilitation Of Karst Valleys

There exists the causality between soil erosion and rock desertification in the formation. Rock desertification is the result of soil erosion for a long time, while soil erosion is the reflection of rock desertification intensity in a certain phase. Soil erosion and disasters of flood and waterlog, ground degeneration resulting from it have become the limiting factors for harmony developments in karst areas. This paper, with a special reference to Huajiang Demonstration Area, studies its effects of water and soil conservation, and discusses the process of soil erosion factors'changes and the rule of erosion value changes during the ecologic restoration. Through the temporal analysis of soil erosion factors and the synchronous comparison of sample sites in different desertification grades, this paper evaluates correctly the effects of water and soil conservation during ecological restoration, which has important practical value to control erosion and ground degeneration, develop agriculture, and improve eco-environment in karst areas.With sample sites as basic units, this paper, on basis of theories of ecology, restoration ecology and sustainable development and by means of erosion lines and sediment trapping dam, surveys soil erosion value of this area. Meanwhile, it uses advanced analytical tools just as GIS and WEPP to study the systematism, relativity and arrangement of soil erosion factors. Then, based on the physical and chemic characteristics of soil and the elements of environment, the paper combines the soil erosion factors with soil erosion value and uses the analyses of frequency, relativity,time contrast and mathematics to compare the factors under different grades of rock desertification, to summarize the effect of soil erosion by those factors, and to generalize the relationship between water and soil conservation and vegetation restoration. The paper systematically discusses the dynamic characteristics of soil erosion and the rules of spatial distribution differences under different grades of rock desertification. At the same time, it makes an integrative analysis on the influences of soil erosion by vegetation coverage rate, root density and physical and chemic characteristics of soil, and on this basis, preliminarily discusses the effect of soil erosion in Huajiang Demonstration Area during the ecologic restoration. On the basis of the research of erosion value, the statistics and analysis of erosion factors under different grades of rock desertification are done, and the quantitative statistic model suitable for forecast and estimation is established for the current situation of soil erosion in Huajiang Demonstration Area.The results are as follows:...