Research On Soil And Water Loss Dynamic Monitoring Technology Of Typical Watershed In Limestone Mountains Based On Multi-Source Remote Sensing

Soil erosion is the result of multiple factors,and it is a normal phenomenon in nature.However,the deterioration of ecological environment,economic losses and other problems caused by soil erosion have a serious impact on human life.Limestone mountain is a high incidence area of soil and water loss due to its large undulating terrain,poor and loose soil and relatively low vegetation coverage.Gushan watershed is a typical area of soil and water loss in limestone mountainous area of Southern mountain region of Jinan,which belongs to the national key control area of soil and water loss.Many rainfall stations and hydrological stations in the watershed can provide important basic data sources for the establishment of dynamic monitoring technology system of soil and water loss.Quantitative monitoring of soil and water loss based on typical watershed can provide important technical support and data base for soil and water conservation in southern mountainous area.Traditional dynamic monitoring of soil and water loss is mainly based on low and medium resolution remote sensing data,whose accuracy is difficult to meet the current needs of soil and water loss monitoring and control.Combining domestic high-resolution satellite data and UAV low-altitude remote sensing data,based on the basic principles of CSLE and SCS-CN,the parameters of the model were optimized and the accuracy was tested.The optimized model was used to monitor and evaluate the soil and water loss in gushan watershed in recent ten years,and the factors of land use,vegetation cover,topography and soil were discussed.The relationship between soil erosion and surface runoff,soil erosion and surface runoff were analyzed.The main conclusions are as follows:(1)Based on the high-resolution remote sensing data,the land use types in the study area are mainly cultivated land,garden land,forest land,construction land,transportation land and water area,with a total of 11 land use types.earth dike terrace and rock ridge terrace are two main soil and water conservation measures in the study area.(2)For soil erosion model,based on the high resolution satellite data and UAV low altitude remote sensing data,this paper improves the accuracy of vegetation coverage extraction and terrain factor calculation,in which the determination coefficient R~2of goodness of fit of vegetation coverage extraction optimization method is 0.7726,and the similarity of histogram frequency curve after terrain factor optimization is 0.94,so as to establish the calculation model of soil erosion with high precision in gushan watershed.(3)For the runoff calculation model,based on the measured rainfall runoff data of 50erosive rainfall events in gushan watershed from 2009 to 2018,the applicability analysis and parameter optimization of the runoff curve model are carried out by using the goodness of fit statistical analysis method and Nash efficiency coefficient method.The runoff calculation accuracy of the optimized Runoff Curve model is significantly improved,and the goodness of fit determination coefficient R~2is improved 113.08%and the Nash efficiency coefficient NSE increased by 137.59%,thus the surface runoff monitoring technology with high accuracy in gushan watershed was established.(4)Based on the analysis of the relationship between soil erosion and surface runoff under different influencing factors,the established soil erosion monitoring technology and surface runoff monitoring technology in gushan watershed were coupled into a dynamic monitoring technology of soil and water loss.The analysis results of spatiotemporal variation of soil and water loss in gushan watershed by using this method showed that:The area of soil and water loss in gushan watershed decreased by 3.18km~2from 2010 to 2019,with an average annual reduction rate of 0.87%.The average annual erosion runoff and sediment concentration of erosive rainfall decreased by 0.21kg/m~3.It was determined that the cinnamon soil area with a slope of 6°to 15°should be monitored.The soil and water conservation control work of orchard,dryland and shrubland should be further strengthened.When the vegetation coverage is between 60%and 75%,the susceptibility of soil erosion can be effectively reduced.