Impacts of a proposed water control project on the inundation regime in China's largest freshwater lake (Poyang Lake): Quantification and ecological implications

Study region: Poyang Lake, the largest freshwater lake in China, is connected to the Yangtze River and has been undergoing shrinkage over the past decade. Study focus: The Poyang Lake water control project (PLWCP) was proposed to protect the lake against rapid shrinkage. However, the quantitative impact of the project on the floodplain inundation regime is not yet clear. This study used a hydrodynamic model to quantify the influence of the PLWCP on the inundation regime of upstream floodplains in Poyang Lake. New hydrological insights for the region: Poyang Lake was characterised by high spatiotemporal heterogeneity in inundation patterns and that the northern lake areas were most affected, followed by the central and eastern lake areas. The western and southern lake areas were less affected. The water levels of the northern channels increased by a maximum of 4-5 m during the first recession period (16 Sep-31 Oct) and increased by 1-2 m during the impounding period (1 Sep-15 Sep). Most of the lake areas except the northern channels showed a water level increase of less than 0.5 m from November to March. The increased inundation areas were mostly 100-400 km(2) (< 20%) and reached greater than 800 km(2) (similar to 30%) from September to October, of which over 300 km(2) (10%) lasted approximately 2 months. Potential suitable habitats in the northern, central and eastern lakes might be impacted.