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I am getting used to Vensim for Modelling System Dynamics. To train, I am busy with a System Dynamics of Park Visitors. Where I have modelling the following Stock and Flow Diagram: SFD

For the equation of 'Max Capacity' I have defined it as:

max capacity = - ( 0.05 * amount of visitors )

And also I have set the initial value to 400.000 visitors per year as a max.

This means that the carrying capacity gets lower by 5% of the total amount of visitors of the previous year. This results into the following diagram: diagram2

Now I want to make the park regain its capacity again. I initially thought of something like:

IF THEN ELSE( Max Capacity < 250000 , 0.05 * Max Capacity, - ( 0.05 * Amount of visitors ))

This gives the following diagram: diagram3

As you see, it doesn't really it just prevents the capacity from ever continuing to decay with 5%.

How can I make it so that the capacity regains again to 400.000 over time?

claudius
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user12368876
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    Hello! Could you give us a reproducible example? Because in this example there's no all equations required to reproduce the behavior observed in the charts. – claudius Jan 09 '20 at 18:08
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    You says that the equation `max capacity` depends of the `amount of visitors`, but in the diagram there's no relationship between these variables... – claudius Jan 09 '20 at 18:12

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