Dynamic changes in soil erosion risk and its driving mechanism: A case study in the Loess Plateau of China

The Loess Plateau has long been considered as a very fragile area that suffers from serious water erosion. With the onset of global climate fluctuations and regional implementation of soil and water conservation measures, it is of great significance to effectively reveal the variations in soil erosion risk and its driving mechanism on the Loess Plateau. Taking the Yanwachuan watershed as a case study and using rainfall, soil, digital elevation model (DEM) and land‐use data, this study applied the Revised Universal Soil loss Equation (RUSLE) model with geographic information system (GIS) technology to analyse the temporal and spatial variations of soil erosion risk and to evaluate the effects of land‐use change and climate change on soil erosion from 1981 to 2016. Future soil erosion risk was also assessed under different land‐use and climate‐change scenarios. Results showed that annual soil loss in the Yanwachuan watershed presented a significant decreasing trend with a rate of 47.928 t km⁻² a⁻¹ and that average annual soil loss was 3,543.7 t km⁻² from 1981 to 2016. However, some areas, even with good vegetation cover, still had a rather high soil erosion risk (exceeding the severe erosion rate of 5,000 t km⁻² in 2000–2016) if located in hilly and gully slope regions. Land‐use change and climate variation contributed 37.2% and 62.8%, respectively, to reducing soil erosion, showing that climate variation played a leading role in current soil‐erosion reduction. In addition, the average soil losses in the 2020s, 2030s and 2040s under different scenarios are predicted to increase by 8.6–42.6% compared with the average soil loss (2,993.8 t km⁻²) in 2001–2016. Future climate change may be the main driving factor in enhancing the risk of soil erosion. Hence, there is an urgent need to strengthen soil and water conservation research and management in future years. HIGHLIGHTS: This study assessed current and future water erosion risk on the Loess Plateau using the RUSLE model. Areas with steep slopes were still experiencing serious soil erosion risk in 2000–2016. Climate change was the main driving factor for soil erosion variation. Future erosion risk is expected to increase under different climate and land‐use scenarios.