Effects of a proposed hydraulic project on the surface water connectivity in Poyang Lake floodplain system, China: Numerical simulation and geostatistical analysis

Study Region: Poyang Lake, the largest freshwater lake in China, has been experiencing persistent shrinkage in recent years.Study Focus: The Poyang Lake Hydraulic Project (PLHP) was proposed to improve water resource and environment carrying capacity, its hydrological effects remain under investigation. This study combined a hydrodynamic model with geostatistical connectivity analysis, to quantify the influence of the PLHP on surface water connectivity in Poyang Lake.New Hydrological Insights for the Region: The PLHP enlarges inundated areas most in the recession period (September-November), accounting for 85% of the total increase throughout the operating period (September-March), and enhances the interconnection probability within these inundated regions. Statistical analysis reveals that the Connectivity Function (CF) in low connectivity conditions (CF <0.4) can be significantly increased by 0.1-0.9, primarily in areas with lower topographies. While for the saucer-shaped sub-lakes, the PLHP can rarely extend the connecting processes between the main lake and sub-lakes in low-water-level conditions below 13 m, which is the lowest threshold height of most sub-lakes. Moreover, most isolated sub-lakes have merged into the main lake when the water level is higher than 14 m, thus the PLHP is no longer effective in this condition. Therefore, the enhancement effect of the PLHP on the connectivity of sub-lakes is restricted in both high-and low-water-level years, and is most pronounced in the medium water-level year.