Understanding thermal stratification and circulation dynamics in Fuxian Lake: Insights from EFDC simulation study

This study aims to provide a comprehensive numerical solution and quantitative analysis of the thermal stratification and circulation in Fuxian Lake, the largest freshwater deep lake in China, utilizing a high-fidelity Environmental Fluid Dynamics Code (EFDC) to build a three-dimensional hydrodynamic model. Simulation results reveal that meteorological conditions and hydrodynamic processes notably influence the spatiotemporal characteristics of the thermocline, with wind and temperature disparities primarily impacting water flow. Maximum water temperature (24.3 °C) and thermocline intensity (0.31 °C/m) typically occur in September. Vertical circulation, driven by wind-induced horizontal divergence and convergence of lake currents, often induces uneven vertical movements, leading to thermocline irregularities. This study also assesses the sensitivity of Fuxian Lake to temperature changes, showcasing the efficacy of EFDC model in accurately reproducing observed spatiotemporal variations. This research not only establishes a foundation for integrating the EFDC model with water quality models but also presents an effective approach for studying hydrodynamics and thermal stratification processes in other deep-water lakes, thereby facilitating lake management and ecological restoration endeavors.