Long-term changes in the drought propagation characteristics in the Yangtze River Basin

Study region: The Yangtze River Basin, crucial for China’s economy and food security, faces growing threats from severe and prolonged droughts, challenging water resources and ecosystem stability. Study focus: Although drought propagation has been widely studied, the long-term evolution of propagation characteristics across large river basins remains poorly understood. This study systematically assesses the long-term evolution of drought propagation characteristics in the Yangtze River Basin (1950–2022). By integrating a 30-year sliding-window framework with copula-based joint probability analysis, we quantify the dynamic trends of drought propagation, focusing on the intensification and prolongation from meteorological to other drought types. New hydrological insights for the region: Drought propagation in the Yangtze Basin shows clear temporal lags and strong spatial clustering, meteorological drought to agricultural drought propagation is dominated by a 2-month lag (64.5 % of the basin), whereas meteorological drought to hydrological drought typically takes 4 months with about 25 % of the basin exceeding 6 months. Sliding-window analysis reveals significant decreases in propagation time in parts of the upper basin, but widespread increases in drought propagation risk, most pronounced in the Sichuan Basin. Areas dominated by cultivated vegetation exhibit longer propagation times and higher risks, with more pronounced upward trends than natural vegetation regions. These results clarify the spatiotemporal patterns and vegetation controls of drought propagation and provide regional knowledge for drought early warning and water resources management. • A framework is proposed to analyze trends in drought propagation characteristics. • Drought propagation time is decreasing in the upper Yangtze River. • Drought propagation risk shows an increasing trend in most areas of the basin. • Cultivated lands are more vulnerable to drought propagation than natural lands.