Future evolution characteristics of hydrological drought in the Yuanjiang River Basin under China's dual-carbon scenarios

As the main stem of the Yuanjiang–Red River, the Yuanjiang River has frequently experienced hydrological droughts in recent years. To reveal the future hydrological drought evolution characteristics of the Yuanjiang River Basin under the dual-carbon scenarios, this study innovatively employed the SWAT model, combined with the SRI, run theory, and Mann–Kendall test, to analyze these characteristics under the dual-carbon scenarios (SSP1-2.6, SSP2-4.5) and the high-carbon scenario (SSP5-8.5) for the future period (2026–2060), in line with China's carbon peaking and neutrality targets. Results showed that under dual-carbon scenarios, the annual and monthly runoff of the basin would increase, hydrological drought would decrease, and all sub-basins would become significantly wetter, compared with the baseline period (1981–2020). Drought duration, severity, and intensity would all decrease, with the reduction magnitude of SSP1-2.6 > SSP2-4.5. Under the high-carbon scenario, the majority of sub-basins would become significantly drier, and drought characteristics would generally increase compared with the baseline (except for individual sub-basins). The analysis indicated that as carbon emissions rose, hydrological drought in the basin would intensify. Promoting carbon emission reduction policies, enhancing water conservancy project construction, and other climate adaptation measures are crucial for alleviating hydrological drought in the Yuanjiang River Basin.