| Soil erosion is one of the most important processes of land degradation in the world,which is considered to be a serious threat to food supply,human health and terrestrial ecosystems.There are significant differences in temporal and spatial distribution of soil erosion,and the causes of soil erosion are complex and diverse.Based on the revised universal soil loss equation(RUSLE),combined with DEM data,multi-temporal remote sensing data,long time series meteorological data and soil property data,the soil erosion in Qinba Mountains from 2000 to 2018 was evaluated.By constructing multiple linear regression equations between soil erosion modulus and environmental variables and bioclimatic variables,three climate scenarios(RCP2.6,RCP4.5 and RCP8.5)and five GCMs models were predicted(BCC-CSM1-1.1,GFDL?CM3,Had GEM2?ES,IPSL?CM5A?LR and Nor ESM1?M)in 2050s(2041-2060).The spatial distribution pattern of soil erosion intensity and the main driving factors of dynamic change of soil erosion were analyzed from different angles(slope,landform type,administrative unit,land use type)and different factors(natural factors and social factors).The main conclusions are as follows:From 2000 to 2018,the annual average rainfall and rainfall erosivity(R)in Qinba Mountains were 766.86 mm and 204.26 MJ·mm·hm-2·h-1·a-1,respectively.The spatial and temporal distribution characteristics of the two indicators decreased gradually from east to west and from south to north.The annual average rainfall and annual average rainfall erosivity in 2010 were significantly higher than those in other years;By adding trend line analysis,there is a good linear relationship between rainfall erosivity and rainfall.Soil erodible factor(K)was affected by soil texture and soil type,and the value of soil erodible factor(K)was between 0-0.34 t·h·MJ-1·mm-1.Slope and slope length factor(LS)is affected by the terrain slope,the high value area distributes in the western Qinba Mountains,the lower value of LS factor distributes in the eastern Qinba Mountains and Hanzhong Basin,and the overall spatial distribution characteristics of LS factor is high in the west and low in the east.Vegetation cover management factor(C)was affected by vegetation coverage,the higher the vegetation coverage,the lower the value of C factor;The C value of vegetation cover and management factor in Qinba Mountains was higher in the west and lower in the east,and higher in the north and lower in the south.The value of water and soil conservation factor(P)depends on the land use type,and the P value of unused land,forest land and grassland are higher than other land use types.The RUSLE model estimates that the average soil erosion modulus of Qinba Mountain from 2000 to 2018 is 4234.47 t·km-2·a-1,and the total annual soil erosion is 12.92×10~8 t;In 2000,2005,2010,2015 and 2018,the average soil erosion modulus was 2549.95 t·km-2·a-1,3699.63 t·km-2·a-1,8131.13 t·km-2·a-1,1916.74 t·km-2·a-1 and 4876.34 t·km-2·a-1,the average soil erosion is 7.75×10~8 t,11.29 ×10~8 t,24.84×10~8 t,5.85×10~8 t,14.88×10~8 t;The erosion situation was lighter in 2015,and the most serious erosion degree was in 2010;the national "Soil Erosion Classification Classification Standard"(SL 1990-2007)was used to classify the erosion intensity of the Qinba Mountains from 2000 to 2018.It is found that the areas with more severe erosion are mainly distributed in the west of Qinba Mountains.The spatial distribution differences of soil erosion intensity under different slope gradients,landform types,administrative units and land use types were analyzed.The results showed that the areas of moderate,strong,extremely strong and severe erosion intensities were mainly distributed in the range of slope gradient > 30 °,and the distribution area was the smallest in the area of slope gradient < 10 °,which indicated that steep slopes would accelerate soil erosion;With the change of time,the erosion degree of low mountains and low middle mountains gradually transferred from slight and light to higher erosion degree,while the erosion degree of high middle mountains and high mountains showed the opposite change trend,which indicated that the soil erosion of Qinba Mountains had gradually transferred from high altitude to low altitude,and the risk of erosion in low mountains and low middle mountains gradually increased;The degree of soil erosion in Gansu Province gradually changed from slight and slight to moderate and strong,and Sichuan Province is the most serious erosion area in five provinces and one city of Qinba Mountains;With the increase of soil erosion degree,the area percentage of cultivated land in each erosion degree decreased gradually,the area percentage of forest land decreased at first and then tended to be stable from 2000 to 2010,and decreased gradually after 2010,while the area proportion of grassland increased gradually.The effects of terrain index,temperature,precipitation,vegetation,soil,population and economic factors on soil erosion were analyzed by Geodetector and Pearson correlation analysis.The results showed that there was no significant correlation between slope aspect and soil erosion;DEM and NDVI were the most important factors affecting soil erosion;Geodetector analysis results show that DEM and NDVI have the highest interpretation of soil erosion in the Qinba Mountains,and they interact with other factors to affect the spatial and temporal distribution of soil erosion in the Qinba Mountains.Multiple linear regression model simulated the linear relationship between soil erosion and environmental variables and bioclimatic variables(R2 = 0.32);Based On the simulated data of three climate scenarios and five global climate models of Worldclim,it is predicted that the soil erosion in the future(2050s)will be more serious than that at present due to the influence of global climate change,and the most serious erosion areas are mainly distributed in the west of Qinba Mountains.And with the change of climate,the soil erosion in Qinba Mountains has increased compared with the current(2000-2018). |
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