Changes in soil erosion and its driving factors under climate change and land use scenarios in Sichuan-Yunnan-Loess Plateau region and the Southern Hilly Mountain Belt, China

Under the influence of climate, tectonics, and topography, soil erosion is most severe in the Loess Plateau and the Southern Hilly Mountain of China, which causes ecological degradation, frequent natural disasters, and other potential dangers. At present, there are few research on the spatio-temporal changes of soil erosion on the Loess Plateau and the Southern Hilly Mountain of China and its underlying mechanism, in particular, tendency projections on soil erosion under climate change and land use scenarios. Therefore, in this study, the Sichuan-Yunnan-Loess Plateau region and the Southern Hilly Mountain belt were selected as the target area to explore the soil erosion change in 2000-2015 using Revised Universal Soil Loss Equation(RUSLE). At the same time, we also predicted the future trend of soil erosion under the combined impacts of climate change(scenarios RCP2.6 and RCP4.5) and land use change. The results show that:(1) soil erosion has been significantly alleviated under the positive effects of vegetation restoration in the Loess Plateau.(2) Soil erosion in the southwestern Sichuan-Yunnan-Loess Plateau region has been significantly alleviated due to the increase in vegetation coverage accompanied by the decrease in rainfall. However, in Sichuan Province, the increased soil erosion occurred due to the increasing farmland in the densely populated areas along with the greatly increased precipitation.(3) The deterioration of soil erosion in some areas took place due to the increasing precipitation in the Southern Hilly Zone.(4) Under future climate change scenarios, rainfall in most parts of the study area will be likely to decrease, which will help alleviate soil erosion. However, most areas of Sichuan, the Loess Plateau and the Southern Hilly Mountain of China will face the pressure of soil erosion due to an increasing farmland. Considering the reduced rainfall under future climate change, it is recommended to increase the proportion of grassland on the Loess Plateau in order to reduce water consumption, while to maintain surface cover to alleviate water and soil erosion at the same time; in addition, each region still needs to control farmland expansion and takes appropriate measures to manage slope farmland and to reduce soil and water erosion in farmland areas.