Soil erosion differences in paired grassland and forestland catchments on the Chinese Loess Plateau

In this study, two adjacent gauged catchments on the Chinese Loess Plateau were selected, in which one catchment was afforested and one was restored with natural vegetation in 1954. The distributions of soil erosion rates were estimated between 2010 and 2020 with a high spatial resolution of 2 m in the paired catchments based on the Revised Universal Soil Loss Equation model (RUSLE) and Geographic Information Systems (GIS). The results showed that the simulated soil erosion rates in 2010-2020 averaged 12.58 and 8.56 t ha(-1) a(-1) for the grassland and forestland catchment, respectively. Moreover, areas with high soil erosion rates (> 80 t ha(-1) a(-1)) were mainly distributed in the topography with steep slope gradients (>45 degrees). Comparisons between simulated soil erosion rates and observed annual sediment loads indicated that the simulation results of the grassland catchment were lower than the observed values, while it was reversed in the forestland catchment. We conclude that the RUSLE model cannot simulate the gravity erosion induced by extreme rainfall events. For the forestland catchment, insufficient streamflow and dense vegetation coverage are crucial factors resulting in hindering the movement of sediments.