Objectives and Scope


This report presents the results of the study described above, the objective of which was: to use the hydrodynamic model of Upper Klamath and Agency Lakes to run experiments with numerical tracers while systematically varying one of three independent variables at a time (wind, lake elevation, and Williamson River inflow), and to use the results for understanding the relative effects of these three variables on flow and transport (the movement of water and passively transported constituents) through both sides of the Delta. An additional objective was to use the results of the experiments to develop multivariate regressions that quantitatively describe the dependence of flow and transport on wind, lake elevation, and Williamson River inflow. The regressions serve two purposes. First, they condense all the tracer experiment results into a single empirical model through which the dependencies are easily visualized, and they therefore contribute to understanding the movement of water and transported constituents through the Delta. Second, these regressions can be used by managers to generate rough but quantitative estimates of, for example, water residence time in the Delta or the rate of water movement through the boundaries of the Delta, for a given set of conditions.


The values of lake elevation and Williamson River inflows used in the tracer experiments spanned a realistic range of conditions, but practical considerations limited the number of elevation and inflow conditions to three elevations between 4,140.5 and 4,142.5 ft (1,262.0 and 1,262.6 m), and the number of inflows to four between 530 and 3,531 ft³/s (15 and 100 m³/s). For the same reason, it was not feasible to run the tracer experiments with all possible realistic wind configurations. Instead, an attempt was made to cover a reasonable range by running the tracer experiments at 5-day intervals between April and September 2008. This resulted in 32 distinct wind scenarios that were used as a forcing function in the tracer experiments.


First posted March 29, 2012