Multivariate spatiotemporal patterns and propagation characteristics of meteorological and hydrological compound hot-drought events in the Yangtze River Basin

Study area The entire Yangtze River Basin, China. Study focus Compound hot–drought events pose increasing risks to water resources, ecosystems, and socio-economic systems under global warming. However, their hydrological manifestations remain insufficiently understood compared with meteorological characteristics. This study identifies compound hot–meteorological and hot–hydrological drought events in the Yangtze River Basin using long-term observations and a joint-threshold approach. New insights for the region Findings show that: (1) compound hot–drought events in the YRB have intensified since the 2000s. Meteorological compound events show increasing event days at most stations, with the largest trend at Hukou (0.19 yr⁻¹). Hydrological compound events also strengthened, with drought intensity reaching 2.36 at Datong and drought severity exceeding 14 at Yichang. (2) Spatially, meteorological compound events increase from western to central–eastern regions, whereas hydrological compound events are stronger in the middle and lower reaches. (3) The propagation time from meteorological to hydrological compound events varies among stations, with the longest lag (8 months) at Yichang. (4) ENSO, PDO, and IOD also exhibit notable associations with compound event characteristics. These findings enhance the understanding of compound hot–drought dynamics and support climate risk assessment and water resource management in the Yangtze River Basin.