Staged water–wetland dynamics in Yangtze-connected Poyang Lake driven by cross-basin compound disasters (1992–2024)

Frequent meteorological disasters increasingly affect wetland ecosystems, yet their long-term impacts on water–wetland dynamics remain poorly understood. This study investigates Poyang Lake, China’s largest freshwater lake hydrologically connected to the Yangtze River, from 1992 to 2024. A spectral-guided hierarchical classification rule set was developed to map open water and wetlands, achieving high accuracy with Kappa coefficients exceeding 0.93. The results reveal strongly stage-dependent responses to compound drought-flood events. During the Wet Season, open water and wetlands showed a negative relationship, with floods generally compressing wetlands and moderate drought promoting wetland exposure. During the Water Recession Period, this relationship weakened owing to temporally compounded events and lake-river interactions. During the Dry Season, water area remained relatively stable, whereas wetlands were less coupled with rainfall but declined sharply under extreme drought. These findings support stage-specific wetland management in large lake-floodplain systems.