Soil Erosion in the Lancang River Basin: Variations, Drivers, and Future Projections From RUSLE-CMIP6.

Soil erosion constrains agricultural productivity, ecological security, and water resources in the Lancang River Basin. This study mapped annual soil erosion at 30-m resolution from 2000 to 2024 using the revised universal soil loss equation combined with Theil-Sen slope estimation and the Mann-Kendall test. Basin-wide mean erosion remained generally stable, while pixel-wise analyses revealed significant localized intensification (p < 0.05) in localized areas. Areas classified as very slight and slight erosion accounted for approximately 55%-73% and 25%-37% of the basin, respectively, whereas moderate-to-extreme erosion occupied <2% of the area. Optimal parameter geographical detector analysis identified precipitation (Q = 0.196) and land use (Q = 0.170) as the dominant controls, with strong bifactor enhancement indicating synergistic effects on exposed slopes. Future erosion for 2025-2050 was assessed using precipitation-driven CMIP6 scenarios (SSP1-1.9, SSP2-4.5, SSP5-8.5) based on the GFDL-CM4 model. Results indicate minimal change under SSP1-1.9, increases of 5%-10% under SSP2-4.5, and pronounced intensification exceeding 10% in parts of the middle and lower basin under SSP5-8.5. Sensitivity analyses confirm that the identified patterns are robust to reasonable uncertainty in land-cover and conservation parameters. These findings provide quantitative guidance for prioritizing soil conservation under future climate change.