The 24th IAHR-APD Congress (24th IAHR-APD Congress)

352 / 2024-02-29 18:35:19

Extreme Hydrological Processes Variations in the River Source Regions in Qinghai-Tibet Plateau

extreme hydrological events,Evolution law,climatic change,The Qinghai-Tibet Plateau

The Qinghai-Tibet Plateau has undergone significant climatic change, leading to an increasing likelihood of extreme hydrological events, e.g. rainstorms and floods, seasonal water scarcity, the shrinkage or even disappearance of lakes and wetlands, and climbing risks of glacial lake outbursts. In this study, the historical evolution characteristics and risks analysis of extreme hydrological events in the river source region were conducted. The variation patterns of precipitation extreme values were analyzed using multi-source remote sensing precipitation datasets including TPHiPr, GPM, and ERA5-land. Additionally, the Lagrange backward tracking model was employed to further determine the stem of precipitation water vapor. The Indicators of Hydrologic Alteration method was used to analyze the variations of discharge extreme value in typical watersheds. Long-term glacier data were used to further analyze the flood risk caused by glacier and snow meltwater and glacial lake outburst. A comprehensive drought index considering snowmelt was constructed to study the evolution characteristics of drought. Results showed that the extreme value of precipitation runoff increased, the water vapor in three rivers source region is mainly transported by the westerlies, the Indian summer monsoon and the East Asian summer monsoon, and the contribution rate of water vapor in the plateau, eastern China and Eurasia is 66.6%, 24.1% and 8.1%, respectively. Lakes in the northeastern part of the Qinghai-Tibet Plateau expanded, the southern part shrank, and the western part first shrank and then expanded, but did not recover to their original state. Although the source region of the Yellow River showed humidification on different time scales, short-term drought occurs more frequently. The proportion of mild drought was the largest, and the rate of decrease is the fastest, and the decrease trend of the total dry area reaches 0.41% per year.