Sensitivity Analysis Simulations

Model sensitivity was evaluated using simulations of the May 2004 storm event. The geomean (50th percentile) simulation for the May 2004 storm event was used as the base simulation (S5) and compared to the effect of varying FC concentrations (S4 25th percentile and S6 75th percentile), increasing flow by 20% (S14), increasing flow by a factor of 2 (S15), applying a constant wind speed of 10 m/sec (22.6 mph) from the SW (S16), and eliminating FC decay to simulate FC inputs as a conservative tracer (S17). All other parameters were held constant.

Simulate Effect of Increasing FC Loading Concentrations

May 2004 storm event with varying FC loading concentrations

S4: FC Loading set to 25th percentile
S5: FC Loading set to 50th percentile (Base Simulation)
S6: FC Loading set to 75th percentile

Open animation of all three simulations

Simulate Effect of Increasing Flows

May 2004 storm event using geomean FC loading concentration and varying flows for all the streams, stormwater outfalls, and WWTPs by a factor of 1, 1.2, and 2.

S5: Flow set to 1.0 (Base Simulation)
S14: Flow set to 1.2
S15: Flow set to 2.0

Open animation of all three simulations

Simulate Effect of Wind

May 2004 storm event using geomean FC loading concentration, flow set to 1 (base simulation flow) and a constant wind speed of 10 m/sec (22.6 mph) throughout the duration of the simulation.

S5: No Wind (Base Simulation)
S16: Constant wind speed of 10 m/sec (22.6)

Open animation of both simulations

Simulate Effect of FC Die Off (Decay Rate Set to Zero)

May 2004 storm event using geomean FC concentration, flow set to 1 (base simulation flow), no wind, and FC decay rate set to zero (FC inputs simulated as a conservative tracer).

S5: Normal FC die off rate (Base Simulation)
S17: No FC die off (Decay set to zero)

Open animation of both simulations