CalSWIM Simulation Tool

Predicting Total Coliform Concentrations
in Upper Newport Bay

Upper Newport Bay acts as a net treatment system and attenuates the magnitude of total coliform contamination/loading received from upstream urban and or natural runoff. This coupled with long and uniform residence times across Upper Bay, justifies the treatment of Upper Bay as a simple continuous stirred tank reactor (CSTR). Total coliform is assumed to flow into the CSTR in surface water runoff from creeks and drains. Inside the CSTR total coliform die-off/re-grow at a rate that varies with solar intensity and various other parameters.

The prototype of the Simulate tool is built so that the user can vary the input parameters to the CSTR model, by increasing or decreasing the combined loading of total coliform from the San Diego creek and Santa Ana Delhi channel, and observing the simulated concentrations in the Upper Bay. The user can also specify the data range for the simulations by selecting a time period. The output of the simulated TC concentrations are shown in the last panel along with other relevant input parameters that are passed on to the model.

(*): The unsteady state solution implies that TC concentrations are predicted using the complete mathematical solution of the CSTR (Continuous Stirred Tank Reactor) model. Not selecting the unsteady state box implies that Quasi steady state solution will be used and varying the load is not permitted. TC concentrations are predicted assuming that the rate of change of concentration of TC at any given instant of time is zero.

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