Numerical modeling of water level and current in very shallow large Lake Poyang

Environmental Fluid Dynamics Code (EFDC) was applied to study the large shallow lake Poyang, which is formed in a three dimensional hydrodynamic frame of Navier-Stokes equations including solving equations of coupled turbulent kinetic energy and turbulent scale, and especially suitable for shallow water study. The numerical scheme of the model is spatial finite difference method in a three time-level, external-internal mode splitting frame. Based on Xingzi station field data, 15 days of calibration was conducted during dry season and flood season in 2008 respectively, using measured bathymetry, rainfall, wind velocity, inflow and outflow data for the section from Duobao Village to Hukou Count in Poyang Lake. During dry season from 2007 to 2008, the lake current is south to north; during flood season in 2008, the lake current in Hukou is turning from northward to southward. The reversion process is important for fresh water exchange between Yangtze River and Poyang Lake, also affording a channel important for fish migration and upgrading of water quality of Poyang Lake. The numerical results were verified by field observation data, and it is suggested the water lock as Poyang Complex project in plan is including a water level adjustment function to reserve the existing water level and lake current variation, and satisfy the demand of biodiversity.