Study On Spatial And Temporal Differentiation Characteristics And Driving Factors Of Soil Erosion In Taizi River Basin

Soil erosion affects the ecological environment and people's production and life.Serious soil erosion will destroy farmland,increase sediment deposition,and affect the water environment and water security.The spatial distribution and evolution of soil erosion is restricted by many factors.The analysis of soil erosion factors and soil erosion process by soil erosion model can provide theoretical basis of the formulation of soil and water conservation measures.Taizi River basin,located in the middle of Liaoning province,is an important commodity grain base of Liaoning province,and also the economic core area of Liaoning and even northeast Asia.With the increase in human activities,regional soil erosion is affected.The study of soil erosion is of great significance of the economic development and ecological balance of Taizi River basin.This paper analyzes the land use and landscape pattern change in Taizi River basin from 1985 to 2018,and studies the dynamic change and driving mechanism of soil erosion in the study area from 1985 to 2018 based on the RUSLE model.The main research results are as follows:(1)The ENVI software was used to interpret the Landsat data onto Taizi River basin of1985 to 2018,and the land use of the fourth phase of the study area was obtained,with Kappa coefficient above 0.8 and high accuracy.According to the national standards to determine six types of land use.It can be seen from the analysis of land use for the basin that forest land and cultivated land are the main types of land use for the basin.The total area of other land type decreases;Farmland and woodland are the main types of land use transfer and transfer in the research area.The land use change in Taizi River basin was gradually stable during the study period.(2)Calculate watershed landscape index based on Fragstats,and analyze the overall characteristics and fragmentation degree of patches,landscape patch shape,and landscape diversity and evenness of each landscape.It can be seen that the number of landscape patches of farmland and construction land is large and the degree of fragmentation is serious.In 34 years,the fragmentation degree of each landscape showed a trend of increasing first and then decreasing.Each landscape patch edge density increases,patch more and more discrete.The diversity index and evenness index of landscape increased,while the dominance degree decreased,indicating that people are making sustainable development of land use whileconstantly transforming land use.(3)The erosion factors of RUSLE model were analyzed based on Arc GIS.The results were as follows: the rainfall erosion factor of the basin was between 2874.2-5447.06(MJ·mm)/(hm2·h),which was strongly correlated with the rainfall distribution.Therefore,the potential erosion of soil in the southeastern mountainous area should be paid attention to.In addition,attention should be paid to prevent the influence of summer rainfall on soil erosion.The erosion factor value of soil is between 0 and 0.43,and the erosion factor value of ordinary luvisol and calcareous coarse bone soil is 0.39.The topographic factor value of the mountain in the southeast of the basin is large,so it is necessary to pay attention to the occurrence of soil erosion and do a good job of the prevention and control of soil and water conservation.The vegetation cover and management factors increased from 1985 to 1996,and the factor values showed a decreasing trend after 1996,indicating that the vegetation coverage of the basin increased after 1996.The soil and water conservation factor was negatively correlated with the C value,and the P value was larger in the southeastern part of the basin,indicating that the measures in the southeastern part of the basin were superior to those in the northwest.(4)Calculate the soil erosion modulus of the study area from 1985 to 2018 based on the RUSLE model,and analyze the soil erosion characteristics.In Taizi River basin,the erosion area decreases from the increase in erosion intensity.The average annual soil erosion was1447.01×104 t.Soil erosion decreased in 34 years,showing a benign development trend.Spatially,the soil erosion of the upper reaches of Taizi River basin is more serious than that in the lower reaches,and the spatial distribution is uneven.Soil erosion of the study area shifted to low intensity,with the most obvious shift from 1996 to 2007.In the upper reaches of Fushun and Benxi,due to the influence of topography and precipitation,the potential erosion of the soil is relatively large.(5)Based on Arc GIS and SPSS,the influence of each factor of soil erosion of the research area was analyzed.The results are as follows: the areas with high rainfall,high elevation and slope of 8°-25° have a large amount of soil loss,which is the key area of soil and water conservation.In soil types,the soil erosion sensitivity of calcareous soil and brown loam soil was higher.However,brown soil is the most widely distributed and the main source of soil loss.In land use,the erosion modulus of unused land was 185.25 t/km2×a,accounting for 24.07% of the erosion modulus of the basin.The soil erosion amount of cultivated land is large,the annual erosion amount is 138.36×104 t,the two are the key areas of soil erosion.In each landscape index,NP,FRAC?AM and CONTAG with the increase of average soil erosion modulus.ED,AREA?MN,SHDI and C were negatively correlated with average soil erosion modulus.It can be seen that artificial intervention in the regularity of patch shape canhelp disperse soil erosion.