Evolution of Compound Drought and Extreme Precipitation Events on the Tibetan Plateau

Abstract The Tibetan Plateau, often called the “Asian water tower,” is highly sensitive to extreme droughts and intense precipitation because of its complex topography and strong monsoonal influences, which pose significant risks to regional and downstream water and ecosystem security. This study uses China Meteorological Forcing Dataset (CMFD) daily precipitation data for 1979–2015 and bias-corrected and downscaled Coupled Model Intercomparison Project phase 6 (CMIP6) daily precipitation data for 2016–2100 to identify and project two types of sequential compound events: drought followed by extreme precipitation (CDEP) and extreme precipitation followed by drought (CWDE). A dynamic identification framework was applied, defining drought with a 30-day precipitation threshold, defining extreme precipitation with a 3-day threshold, and pairing events within intervals from 1 to 3 months. Our results show that the frequency of both CDEP and CWDE increases markedly with longer lag times. During the historical period, event hotspots were concentrated in the southern and central Plateau. Under future shared socioeconomic pathway (SSP) scenarios, CDEP risk expands northward into interior arid regions such as northern Tibet and the Qaidam Basin, while CWDE remains centered in the south and central Plateau but extends toward inland areas. Importantly, the increase in event frequency is not monotonic with warming; the strongest enhancement occurs under moderate emissions, specifically SSP2-4.5 and SSP3-7.0. Overall, warming and a moister atmosphere intensify the alternation between dry and wet extremes, driven by enhanced monsoonal moisture transport, orographic lifting, and stronger land–atmosphere coupling. These findings provide a scientific basis for improving drought and flood risk management and climate adaptation strategies in high mountain watersheds of the Tibetan Plateau. Significance Statement This study examines two sequential extremes on the Tibetan Plateau: CDEP and CWDE. CDEP is drought followed by extreme precipitation, and CWDE is extreme precipitation followed by drought. We evaluate how both change over time. The results show that in the historical period, the frequency of these compound events rises with longer intervals, with hotspots in the southern and central Plateau. In the future, across all emission scenarios, CDEP events are projected to strengthen in the northern and drier regions, while CWDE events will remain most common in the south and center and will extend into inland areas. These changes are driven by orographic lifting, monsoon moisture transport, and stronger land–atmosphere coupling under warming. They will worsen water shortages and flood risk, increasing the challenges for water resources management and ecosystem protection. This study provides essential scientific guidance to help policymakers and communities prepare for more frequent and more intense transitions between drought and flood in alpine watersheds.