Projected seasonal changes in future rainfall erosivity over the Lancang-Mekong River basin under the CMIP6 scenarios

Climate change is a driver of soil erosion, but the future projections of seasonal rainfall erosivity variability and spatial distribution over the Lancang-Mekong River Basin (LMRB) are still not well understood. Based on the bias-corrected precipitation data from five General Circulation Models (GCMs) in the sixth phase of the Coupled Model Intercomparison Project (CMIP6), the impacts of future climate change on the seasonal rainfall erosivity over the LMRB were assessed using three widely applied empirical daily rainfall erosivity models under three combined scenarios of the Shared Socioeconomic Pathways and the Representative Concentration Pathways (SSP1-RCP2.6, SSP3- RCP7.0 and SSP5- RCP8.5). The results show that rainfall erosivity would generally increase in the near term (2030–2060) and far term (2070–2100), and more ensemble members agree with the increase in rainfall erosivity, especially under the high emission scenarios in the far term. In the near term, the ensemble mean of basin-wide rainfall erosivity would increase by 2.5%-8.7% compared to the baseline period (1980–2010), while in the far term, the ensemble mean would increase by 12.2%-31.0%. Seasonal variations in rainfall erosivity show that summer rainfall erosivity from June to August accounts for more than two-thirds of the total annual rainfall erosivity. Although the projected basin-wide average summer rainfall erosivity would increase, the mid-southern basin in Thailand and southern Lao PDR would experience a decrease. For rainfall erosivity from March to May, large areas except for the mountainous part of China would also experience a decrease in seasonal rainfall erosivity. The projected changes in rainfall erosivity can contribute to a better understanding of soil erosion risk under climate change across the LMRB.