Towards a more comprehensive scenario analysis: Response of soil erosion to future land use and climate change in the Central Yunnan Urban Agglomeration, China

Rapid urbanization and climate change exacerbate soil erosion globally, threatening ecosystem services and sustainable development. However, current predictive studies on future soil erosion often lack comprehensive consideration of the interactions between land use and climate change. This study proposed a comprehensive scenario analysis framework that integrated four Shared Socioeconomic Pathways (SSPs) from CMIP6 with four bespoke land-use scenarios (Inertial Development (IDS), Urban Development Priority (UDPS), Ecological Protection Priority (EPPS), and Farmland Protection Priority (FPPS)) to create 16 future scenarios, allowing for a more nuanced understanding of potential soil erosion trajectories. The results indicated that (1) compared to the baseline period (2000-2020), future soil erosion in the Central Yunnan Urban Agglomeration (CYUA) would improve, albeit with significant differences among the scenarios. The most notable improvement was under EPPS + SSP1-2.6 scenario (ScC1). (2) The lower Jinsha, upper Nanpan, and Red river basins were high-risk areas for soil erosion in the CYUA, each dominated by different factors, necessitating differentiated soil erosion control measures. (3) Land-use and climate change jointly influenced the direction of erosion development, with the lightest erosion occurring under the EPPS and heaviest erosion occurring under the FPPS. The largest decrease in erosion occurs under SSP1-2.6, whereas the smallest decrease occurs under SSP5-8.5. (4) Climate change had a more significant impact on soil erosion than land-use change, with the reduction rates of the soil erosion modulus and area between different climate change scenarios relative to the past 20 years being 9% and 3.77%, respectively, approximately eight and four times the magnitude of change under different land-use scenarios. This study recommends reducing carbon emissions, enhancing vegetation cover, and controlling slope land development to effectively mitigate the soil erosion risk in CYUA and promote regional sustainable development. The proposed comprehensive scenario analysis method provides new insights into future global small-scale regional predictions.