Three-dimensional Management Model for Lake Washington, Part I: Introduction and Hydrodynamic Modeling

A three-dimensional hydrodynamic model, CH3D-Z (curvilinear hydrodynamics in three dimension, Z-grid version), was implemented in Lake Washington as a part of a management model. The model was calibrated for hydrothermal distribution over a one-year time period for 1995 and verified for a two-year time period between 1996 and 1997. Simulation reproduced intra-annual variation of mixing represented by fall/winter mixing and spring/summer stratification. The simulated variation of vertical thermal structures also matched observation. Vertical flux was investigated in terms of stratification through turbulent mixing and internal waves. Basin scale internal waves showed a characteristic diurnal variation and modulation by surface wind. The model resolved the seasonal variation of thermal structures, assuring a good linkage to a nutrient-eutrophication model.