One more way to address the seasonal water shortage of the largest freshwater lake in China? A nature-based solution through lake bathymetry restoration

Poyang Lake, the largest freshwater lake in China, is a critical water resource and ecological hub. However, seasonal dryness has raised significant concerns about the sustainability of its hydrological regime. This study investigates the potential of morphological restoration as a nature-based solution to mitigate Poyang Lake’s seasonal water shortages. A hydrodynamic model simulated water level, depth, and velocity changes under four scenarios where the lakebed morphology of three severely incised areas was restored to 1998 conditions. The simulations evaluated the hydrodynamic impacts of restoration, focusing on its implications for water resource management and ecological functions. Results revealed significant impacts of bathymetry restoration, particularly during low-water-level periods. Water depth in the upstream main channel increased by 0.5–2.5 m and by 0.1–0.5 m in the floodplain during the dry season. Water velocity showed contrasting trends, decreasing by 0.01–0.1 m/s in the main channel and increasing by 0.01–0.1 m/s in the floodplain. Nonlinear correlations between water depth increases and baseline water levels highlighted the most pronounced effects during dry seasons. The study demonstrates that bathymetry restoration may be a promising strategy for addressing water shortages in the dry season. However, trade-offs among multiple ecosystem services and an optimization procedure should be used in future to select the different opportunities for restoration planning. • A nature-based solution was proposed to address seasonal dryness in a floodplain lake. • Hydrodynamic effects of bathymetry restoration in severely incised areas were modeled. • Remarkable increases in upstream water level/depth were found during the dry season. • Magnitude of water level elevation were most pronounced during low-water level periods. • Synergies and trade-offs of multifunctionality should be considered during optimization.