| The large-scale project of returning farmland to forest and grassland in the Loess Plateau has effectively improved the regional soil erosion problem,and greatly changed the regional land use pattern and climate.The three are closely related.Assessing the spatial and temporal evolution of soil erosion in the past and predict the development trend of soil erosion under future land use and climate change conditions.This can understand the effect of soil erosion control in the past and provide scientific reference for future regional soil erosion control and land use policy formulation.In this study,the Jiuyuangou watershed,a typical watershed in the hilly and gully region of the Loess Plateau,was selected as the research object.The temporal and spatial evolution of land use and vegetation cover in the Jiuyuangou watershed from 2010 to 2020 was systematically analyzed.The Chinese soil erosion equation(CSLE)was used to explore the spatial and temporal distribution pattern of soil erosion to reveal the spatial and temporal variation characteristics of soil erosion,and the response relationship with land use change(LUCC).Based on the FLUS-CSLE model and different climate models of CMIP6(SSP126,SSP245,SSP585).The spatial pattern of land use in different scenarios in the future(2025,2030)of the basin was evaluated.At the same time,different land use change and climate change scenarios(A1-A3: natural development scenario and its corresponding climate model,B1-B3: ecological protection scenario and its corresponding climate model,C1-C3: economic growth scenario and its corresponding climate model)were constructed to predict the development trend of soil erosion in the future.The results showed that:(1)The spatial pattern of land use and vegetation coverage in the Jiuyuangou watershed changed significantly.The land use types are gradually concentrated,grassland and forest land are the main land use types in the basin,followed by cropland,building,and water.The center of gravity of vegetation coverage in the Jiuyuangou watershed migrated to the northeast.The vegetation in the low-elevation area was stable and continued to develop well.The situation in the middle and high areas was inverse.The area of vegetation degradation increased first and then decreased with the increase of slope.(2)The spatial and temporal distribution of soil erosion in the Jiuyuangou watershed changed significantly.During the study period,the area of weak and moderate erosion increased,and the area of other erosion intensity grades decreased.From 2015 to 2020,soil erosion intensity increased in 70 % of the study area.The main soil erosion intensity grade increased first and then decreased with the increase of elevation,and the main soil erosion intensity grade gradually increased with the increase of slope.From 2010 to 2015,the fragmentation of weak,slight and moderate erosion decreased,and weak erosion became the main erosion type.From 2015 to 2020,the dominance of strong and above erosion increased.(3)There are significant differences in soil erosion among different land use types.The soil erosion modulus of different land use types is: cropland > grassland > building > forest land.Overall,from 2010 to 2020,the soil erosion of different land use types in Jiuyuangou watershed decreased before 2015 and then increased.There was a high spatial correlation between LUCC and soil erosion in the northeastern,central,and southwestern parts of the basin.(4)In the future,soil erosion will continue to improve in A and B series scenarios,and there is a risk of soil erosion rebound in C series scenarios.The average value of rainfall erosivity in the basin under different climate models from 2025 to 2030 is SSP126,SSP245 and SSP585 from small to large.The spatial pattern of rainfall erosivity is likely to show an increasing trend from southwest to northeast.In different scenarios,the soil erosion modulus in 2025 and 2030 decreased compared with 2020 except for the C2 scenario in 2030.In A and B series scenarios,the average soil erosion modulus in 2030 decreased compared with that in 2025,and the average soil erosion modulus in the C series scenarios increased.(5)Soil erosion modulus of different land use types under different combinations of land use and climate change scenarios ranked from large to small are cropland,grassland,building,and forest land.The magnitude of changes in soil erosion modulus of different land use types from 2025 to 2030 is the largest under Scenario A and the smallest under Scenario C.The erosion modulus of cultivated land and forest land decreased under Scenarios A and B but increased under Scenario C,while that of grassland increased under Scenarios A and B but decreased under Scenario C.The erosion modulus of urban land decreased under Scenario A but increased under Scenarios B and C. |
