CALIBRATION AND APPLICATION OF A 2-DIMENSIONAL HYDRODYMANIC AND WATER QUALITY MODEL OF LAKE MOHAVE, NEVADA

A water quality model of Lake Mohave was developed to estimate the effects of changes in nutrient load on 1) the in-lake water quality and 2) the nutrient load discharged downstream of Davis Dam. The model chosen was CE-QUAL-W2, a time varying, longitudinal-vertical hydrodynamic and water quality model maintained by the Waterways Experiment Station of the US Army Corps of Engineers. The setup of this model for Lake Mohave included a representation of the lake bathymetry and development of time varying boundary condition data sets for the period 1981-1982. Simulation results were compared to observations to ensure that the model reproduced the observed behavior. Changes were required in the model parameters and formulations to produce an adequate match.The model will be used to assess the response of Lake Mohave to various engineering alternatives. A separate model for Lake Mead is being developed at Flow Science Inc. that will provide as one of its outputs the nutrient load to Lake Mohave under these engineering alternatives. The engineering alternative scenario definitions and the calibrated Lake Mead model are not final at this time. Therefore, two hypothetical simulations were made to illustrate the range of effects expected from the model. Results of these simulations suggest that the nutrient added in excess of existing loads will be partially retained in the lake. The percent retention of excess load appears to be higher than the retention of the existing load.