漓江流域气象-水文干旱时空演变规律及传播特征研究OA

The increasing frequency of extreme drought events in southern China has severely impacted regional water security and socio-economic development.Focusing on the Lijiang River Basin,this study investigates the spatiotemporal evolution and propagation laws of meteorological and hydrological droughts at various time scales based on the Standardized Precipitation Index(SPI)and Standardized Runoff Index(SRI),utilizing the Mann-Kendall trend test,Pettitt abrupt change test,run theory,and Pearson correlation analysis.The results indicate a high frequency of extreme meteorological drought events within the basin,whereas hydrological droughts are primarily categorized as mild to moderate.Both SPI and SRI indices exhibit an increasing trend at monthly and annual scales.Significant abrupt changes in hydrological drought were detected at the Lingqu,Chaotian,and Pingle stations.Under mild drought conditions,meteorological droughts are more frequent but shorter and less intense than hydrological droughts.During moderate droughts,the upper basin demonstrates a drought amplification effect,while the middle and lower reaches exhibit stronger drought resilience.The propagation time from meteorological to hydrological drought ranges from 1 to 4 months,and this propagation time increases progressively from upstream to downstream.In 2022,a typical year with an abrupt wet-to-dry transition,the basin exhibited a wet state on an annual scale,yet SPI and SRI shifted by 2.79 and 3.08 on average from spring-summer to autumn-winter.At both monthly and seasonal scales,this year was characterized by frequent but mild meteorological droughts alongside rare but severe hydrological droughts.