Merger Exercises
1. Build and Verify the Simulation with a Sustained
Population
Build the model in Figure 1, set the step size to 1 month
and generate a 48 month simulation to verify the results in Figure 2.
2. Verify the Simulation with a Declining Population
Then set the length to 1200 months and adjust the elevation to match the
"step down" pattern in Figure 3. Simulate the model to verify
that the population of adults agrees with the results in Figure 3.
3. Model Merger and Sustained Population Test
Reconfigure the water balance model to operate on a monthly basis (see the 4th exercise in Chapter 4.) Combine the two models as two sectors within a single model. Set the initial volume of water in Mono Lake to ensure that the simulation begins with the elevation near 6380 feet. Set the water export at a constant value that will ensure that the elevation remains near 6380 feet. Run the new model over a 48 month interval to verify that the brine shrimp population matches the results in Figure 2.
4. Impact of High Exports
When you are satisfied with the previous test, change the export to 100 KAF/year and simulate the model over a a 600 month interval to show the impact of maintaining exports at the high level that was permitted in the past.
5. Reacting to Reduced Brine Shrimp Population
Conduct a test similar to Figure 4.14 in the book using the size of the brine shrimp population as an indicator of the health of the lake. Set export at 100 KAF/yr in the early years of the simulation. Locate the time point in the simulation when the adult shrimp population in the 7th month falls below 20 ks/sm. Set export to zero at this point and for the remainder of the simulation. Turn in a time graph similar to Figure 4.14 to document your results. Does the time graph show a recovery of the brine shrimp population?
6. Export Policy Based on Brine Shrimp
Recall the "buffer policy" from the 3rd exercise in Chapter 4 which controls the water export as a function of the simulated lake elevation. Examine a new buffer policy with export controlled by the size of the brine shrimp population that appears in the lake each summer. Assume that our goal is to maintain the shrimp population at 25 ks/sm or higher. (For example, we may want to maintain suitable summer stopover habitat for the Eared Grebe.) Can you devise an export policy that protects the simulated brine shrimp population? How does the annual water export under the new policy compare with the water export allowed in the 3rd exercise from Chapter 4?
7. Export Policy with Uncertainty in Cyst Hatching
Many of the parameters in the brine shrimp model are highly
uncertain. Let's select the cyst hatching fraction for closer examination.
Assume that the 60% hatch at low salinity is well known and the 0% hatch
at extremely high salinity is also well established. But the hatching fractions
for intermediate values of the salinity are highly uncertain. Change the
nonlinear relationship between the cyst hatching fraction and the salinity
in two sensitivity tests.
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