Extreme Hydrological Events and Lake-Wetland Landscape Dynamics: Toward Adaptive Management in Large Freshwater Systems-Insights from Poyang Lake, China

Abstract

Extreme hydrological events induced by climate change pose significant challenges to the ecological stability of river-connected lake-wetland systems. Poyang Lake, China’s largest freshwater lake, provides an ideal case for investigating landscape responses to compound drought and flood disturbances. This study quantifies the propagation process from meteorological drought to hydrological drought and identifies critical water level thresholds governing abrupt landscape transitions. By integrating remote sensing data, drought indices, Morphological Spatial Pattern Analysis (MSPA), and piecewise regression, we evaluated nonlinear landscape responses to extreme water level fluctuations. The results showed that the optimal lag time for lake water area response to meteorological drought was 21 days. Landscape connectivity exhibited nonlinear responses to water level variations, with 12.50 m and 12.73 m identified as critical thresholds for maintaining lake-wide connectivity and core deep-water habitats, respectively. The 9.75–14.44 m water level range was identified as the key sensitive interval associated with rapid landscape reorganization. Moreover, landscape responses showed significant spatial heterogeneity, with the Nanji Wetland National Nature Reserve being more sensitive to drought-induced fragmentation than the Poyang Lake National Nature Reserve. These findings provide quantitative thresholds and adaptive management implications for improving the resilience of floodplain lake-wetland systems under increasing hydrological extremes.