Variation of hydro-climatic extremes in headwater regions of Hei River basin under climate change

Study region: Headwater regions of Hei River basin, located in the northeast of Tibetan Plateau. Study focus: Hydro-climatic extremes analysis for historical (1971-2015) and future (2024-2100) period. New hydrological insights for the region: Remarkable climate change has been observed in high mountain areas, which may result in more frequent hydro-climatic extremes. Investigating hydroclimatic extremes variations is important for mitigating hydro-climatic disasters and implementing water resource management. Warm extremes present an increasing trend in frequency and magnitude for historical and future period, while the cold extremes show a decreasing trend in the study area. Meanwhile, frequency and amount of precipitation extremes present an increasing trend for historical and future period. As a result, the intensity of meteorological and hydrological droughts show decreasing trends while floods present an increasing trend, indicating a certain drought relief in the study area. But future occurrence of extreme droughts or floods will increase. Moreover, floods for different return periods will rise with different change rate under different scenarios (SSP 1-2.6, SSP 2-4.5, SSP 3-7.0 and SSP 5-8.5). Therefore, extreme floods or droughts risks should not be underestimated and need be addressed accordingly. The findings highlight the importance of adaptive strategies to cope with more frequent hydro-climatic extremes under climate change.