II.3.4 - Modes of Operation

The Scenario Mode runs one year with as many releases as desired. It can be used to gain insight on the effects of changes in system parameters on the survival and migration of fish during a single water year. In this mode, natural unregulated inflows are specified. These flow into the mainstem rivers and storage reservoirs at headwaters. System operation and fish biological parameters can be varied stochastically according to user specifications.

The Monte Carlo Mode runs CRiSP.1 for one or more combinations of water year and system operations. Flows are specified at the project, not headwaters. In each run, a different flow regime and other model parameters are used. Fish survival is determined for each run and the distribution of survivals from all runs provides an estimate of the probability distribution of survival under the specified conditions.

The main variable changed in each run is river flow. These are generated from runs of the hydrosystem models maintained by the Army Corps of Engineers (HYSSR) and the BPA (HYDROSIM) (Fig. 9). The flow models use historical water data and a projection of electrical demand to simulate system flows, which are designated Flow Archive Files. These files give period-averaged flows at operating projects which are modulated by CRiSP.1 to represent daily flows. CRiSP.1 uses the modulated flows along with input data files describing the system operations and fish biological parameters to produce histograms of survival (Fig. 9).

Fig. 9 Interaction of flow model and CRiSP.1 in Monte Carlo Mode