Case Studies:Several Models for LAR Temperature Study

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Lower American River near Sacramento California, USA

Project Overview

Report: "Temperature Modeling of Folsom Lake, Lake Natoma, and the Lower American River" prepared by Merlynn D. Bender, Joseph P. Kubitschek, and Tracy B. Vermeyen, Bureau of Reclamation, Technical Service Center, Denver, Colorado, April 2007. (79 pages plus five appendices)

The combination of a CEQUALW2 model of Folsom Lake, a CEQUALW2 model of Lake Natoma, a Flow3D CFD model of Nimbus Dam forebay, and a RMS (ADYN/RQUAL) model of the Nimbus Dam tailwater to the Sacramento River were used to model water temperature in support of anadromous fish restoration studies.

Model Applications

Hourly peaking power operations and water temperatures of the Lower American River from the headwater of Folsom Lake to the confluence with the Sacramento River were modeled in combination with a fine grid (5 foot cubes) computational fluid dynamics (CFD) model of the Nimbus Dam forebay to estimate the effects of five identified actions that may improve transport of cold water through Lake Natoma and reduce the temperature of the lower American River. Hourly two-dimensional (laterally averaged) CEQUALW2 models of Folsom Lake and Lake Natoma provided a thorough understanding of the reservoir stratified environments. The ADYN/RQUAL one-dimensional riverine model with an internal boundary condition at the weir with pickets that restict fish movement was used to provide longitudinal and diel variations in river temperature under varying meteorology, release temperature, and release rate. The CFD three-dimensional model used quasi steady-state boundary conditons to estimate the near-field hydraulic effects on flow patterns and vorticity and changes in release temperature due to debris wall removal and installation of a powerplant intake curtain. The combination of several individually calibrated models with different strengths provided a good understanding of the system-wide effects on water temperature for fishery studies.

Report Link

A link for the modeling report is at:

Several Models for LAR Temperature Study