Comparison of a 2D and 3D Hydrodynamic and Water Quality Model for Lake Systems

A two and three-dimensional hydrothermal numerical model were developed and calibrated for Laurance Lake, Oregon, USA. The numerical scheme in the two-dimensional laterally averaged hydrodynamic and water quality model, CE-QUAL-W2, was adapted for a three-dimensional model, called W3, to solve the governing equations of continuity, free surface equation, and momentum. In order to perform an equivalent comparison between the results of the two and three-dimensional model, both models were run using the same meteorological data, boundary conditions of flow and temperature, and surface heat exchange algorithms. The reservoir water levels and temperature were calibrated over the simulation period. Even though the calculated error statistics of the 3D model were slightly higher compared to the 2D model, the numerical predictions of both models had good agreement with field data. Conditions where a 2D or a 3D model is better suited to a lake or reservoir were discussed.