Modeling and model validation of wind-driven circulation in Upper Klamath Lake, Oregon

The hydrodynamics in the Upper Klamath Lake (UKL) plays a significant role in the water quality conditions of the lake. In order to provide a quantitative evaluation of the impacts of hydrodynamics on water quality in UKL, a detailed hydrodynamic model was implemented using an unstructured grid 3-D hydrodynamic model known as the UnTRIM model. The circulation in UKL is driven primarily by wind. Wind speed and direction time-series records were used as input, the numerical model reproduced the wind "set-up" and "set-down" at down wind and upwind ends of the lake, respectively. Of the two acoustic Doppler current profiler (ADCP) records, the UnTRIM model reproduced the measured velocity at the deep station. At the shallow station, the model results showed diurnal patterns that correlated well with wind variations, but the measured velocity showed water velocity sustained at 3 to 5 cm/sec or above. Discrepancies between the model results and observations at the shallow ADCP station is discussed on the basis of correct physics. If the field measurements are inconsistent with the known physics, there exists the possibility that the field data are suspect or the field data are revealing some physical processes that are not yet understood. Copyright ASCE 2005.