Study On Landscape Pattern And Soil Erosion Based On Granite Region In South China And Landscape Optimization

The granite area in the south is a serious soil erosion area in China,and Anxi County is one of the typical areas of granite soil erosion in the south.It has attracted much attention from the government and people.Therefore,in this context,the relationship between landscape pattern and soil erosion in Xixi River Basin of Anxi County has been studied.On this basis,the landscape pattern is optimized from horizontal and vertical space in order to reduce soil erosion,and it provides a reasonable,scientific theoretical basis to keep soil.In this study,the Xixi watershed in the collapse-prone area of Anxi County is the main research background,the land use map,and the soil erosion map and the DEM topographic map is the main data source.Integrated use of landscape ecology theory and topographic index theory and BP neural network model,the minimum cumulative resistance model and ArcGIS technology,the influence of landscape pattern on soil erosion is analyzed from the perspective of land cover and topographic factors.Based on the above study on the influence of landscape pattern on soil erosion,the relationship between landscape pattern and BP model nonlinearity is established from the perspective of landscape pattern,and the landscape pattern is optimized with the actual control engineering measures to minimize the soil erosion.From the perspective of vertical space,according to the landscape pattern and process theory,the minimum cumulative resistance model is used to establish the soil conservation area,and the landscape pattern is further optimized combinating to its landscape type distribution and terrain index to reduce soil erosion.Based on this study,we can provide theoretical support and reference for soil erosion in order to optimize the landscape pattern in the red soil granite area of southern China.The paper draws the following main conclusions:(1)The landscape pattern and soil erosion of the study area were analyzed by ArcGIS and Fragstats software.The results showed that:The study area is mainly based on mountain landscape,tea garden landscape and farmland landscape with mountain forest as the landscape matrix as well.Soil erosion mainly occurs in tea garden landscape and bare landscape with mainly mild and moderate erosion;The land loss rate of construction land(farmland,river and reservoir)is small but the density of building landscape patch and fragmentation is big.(2)Effect of landscape pattern on soil erosion based on topographic factors.In the slope landscape pattern analysis,the average rate of soil erosion is high at the slope of 15 °-25 °.The average shape index of the area weight is the same as soil erosion rate,the landscape connectivity is on the contrary.The patch edge effect is greater,the landscape connectivity is smaller,Soil erosion occurs mainly in low volcanic forests and undulating hills.The number of patches,landscape shape index and area weighted average shape index of soil erosion has a positive effect.The landscape connectivity of soil erosion has a negative impact.(3)According to the influence of landscape pattern on soil erosion,the BP model is used to construct the nonlinear mapping relationship between landscape pattern and soil erosion area.Based on this model,soil erosion situation is optimized.The results show that the relative error of BP model is less than 5%which indicates that there is a high precision BP mapping relationship between landscape pattern and soil erosion area.By optimizing the landscape pattern of tea garden and bare land,the area of soil erosion is forecast to decrease by 9.27%.Therefore,the BP mapping relationship can be used to optimize the landscape pattern to predict soil erosion and to provide reference for guiding soil erosion control.(4)Based on the geomorphic index theory and the minimum cumulative resistance model,the surface of soil conservation resistance is established and divided into low safety soil conservation area,middle safe soil conservation area and higher soil conservation area.On this basis,Landscape type and topographic index and optimize the landscape pattern in order to reduce the soil erosion.The results show that:in the area where the terrain index is less than 1.11,rational construction land is used and a small watershed comprehensive management area is established.In the area where the terrain index is less than 1.11-1.89,dry land scattered around is integrated into tea garden to be set up a "tea garden-water conservation ecological zone".While the area where the terrain index is more than 1.89,it will be set up a model of model of"collapse hill-water conservation ecological zone-eco-tourism area".And it will optimize the way to reduce soil erosion.