| The Xiangjiang River is an important strategic resource in Hunan and an important strategic resource in China,and the development of the Xiangjiang River Basin affects Hunan’s ecological security and economic development.Based on GIS technology,this paper uses satellite images of the Xiangjiang River Basin as the basic data,and studies and classifies the land use types in the Xiangjiang River Basin.The land use in the Xiangjiang River Basin in the past 20 years was studied,and the changes(increase or decrease)and different land use modes in different periods were discussed,and the dynamic characteristics of their changes were analyzed.The RUSLE model was used to determine the values of each factor in the RUSLE model in the Xiangjiang River Basin and analyze the characteristics of soil erosion time.On this basis,through the study of annual precipitation,land use type and vegetation coverage in the Xiangjiang River Basin,the relevant laws of soil erosion and change in the Xiangjiang River Basin were revealed.Then,based on the three-stage DEA model,70 counties in the Xiangjiang River Basin were in-depth researched,and the soil erosion risk assessment of land use was considered considering environmental factors,so as to provide a reference for the land development plan of the Xiangjiang River Basin.The main findings of this paper are as follows:(1)Land use change.The results show that there has been a significant change in the area of land use type.In the past 20 years,cultivated land,forest land and construction land have changed the most,among which the change of construction land is the most drastic.From the overall comprehensive point of view,the construction land continued to increase in four stages,of which the increase was the most obvious from 2005 to 2010,with an increase of 451km2;The cultivated land area increased in 20002005,2005-2010 and 2015-2020,and only in 2010-2015 it was in the stage of decrease,but the decrease was much less than the increase,so the overall four stages still increased;Shrubs,grasslands,and water bodies continued to decrease in the four stages,but the reduction was small,almost close to 0;Forest land decreased in 2000-2005,2005-2010 and 2015-2020,and increased in 2010-2015,and the decrease was most pronounced in 2005-2010,with a decrease of 2423km2,so the area of forest land decreased throughout the change.The overall change of land use area showed an upward trend.Cultivated land showed an overall upward trend from 2000 to 2020;From 2000 to 2020,forest land continued to be converted to arable land and construction land,at a relatively fast rate;From the overall results of 2000-2020,the speed of water is decreasing,but the speed is slower;The overall results of grassland showed that it was constantly changing to other land types,and the rate was slow.Construction land continued to rise from 2000 to 2020,and rose rapidly in 2010-2015 and 2015-2020.Through the above analysis,the land use types in the Xiangjiang River Basin are mainly forest land,cultivated land and construction land,and these three land types change the most,and the decrease of forest land is the inevitable result of the increase of cultivated land and construction land.(2)Changes in soil erosion.During the entire study period from 2000 to 2020,the erosion status in the study area was dominated by intensity erosion,followed by micro erosion and mild erosion,and the erosion area increased significantly at each stage,and the area of mild erosion increased in 2015,but the area of intensity erosion and other erosion intensity decreased,indicating that the strong erosion was alleviated and the erosion intensity decreased during this period.The characteristics of each precipitation interval are mainly mild erosion in the range of 1500-1800mm.From 2000 to 2020,soil erosion mainly occurred in the woodland area of the Xiangjiang River Basin,showing a state of mild erosion and continuous growth.Grass and shrubs are moderately eroded,but negligible due to their small area.Water areas and construction land are slightly eroded,but the amount of erosion is increasing.The soil erosion intensity in the Xiangjiang River Basin decreased with the increase of vegetation cover,and the richer the vegetation cover,the better the erosion resistance.The amount of soil erosion is decreasing,and the average erosion modulus is decreasing,but the affected area is increasing.(3)Using the traditional DEA model,the average overall soil erosion disaster risk in each county during the 10-year period in the Xiangjiang River Basin was 0.57,and after the SFA regression model eliminated the influence of environmental variables,the average overall soil erosion disaster risk in each county in 10 years was 0.32,indicating that environmental variables had a significant impact on soil erosion disaster risk assessment.At the same time,the increase of runoff,GDP and dike slope length will reduce the risk of soil erosion disaster,while the increase of soil erosion rate will increase the risk of soil erosion disaster,and the impact of various environmental variables on soil erosion disaster risk in different counties in the Xiangjiang River Basin is different.(4)The impact of land use change on soil erosion disaster risk is spatially heterogeneous,and the impact of land use on soil erosion disaster is different in different counties.The counties with high risk of soil erosion disasters are mainly distributed in the northwest and central regions of the Xiangjiang River Basin,which are the main product producing areas in the Xiangjiang River Basin,mostly located in low-altitude plains,and frequent cultivated land reclamation activities are easy to destroy soil structure and ecosystem balance,so land activities increase the risk of soil erosion disasters.The counties with low risk of soil erosion disasters are mainly distributed in the southeast of the Xiangjiang River Basin,and the southeast is mostly high-altitude forest land,with less human activities and fewer disturbance factors of soil erosion disasters,so the risk of soil erosion disasters is low.(5)The proportion of land use that does not contribute to soil erosion risk reflects the drivers of soil erosion risk,and the drivers of soil erosion risk are different in different counties,that is,not all land-use inputs cause soil erosion risk,and the same land-use input contributes to soil erosion risk or does not contribute.The vulnerability of land development in each county can be obtained through a comprehensive soil erosion risk assessment and the number of unutilized inputs. |
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