Understanding the step response pastas

[martafaneca]

Could you help interpret the step-reponse graphics generated with pastas? And is it possible to obtain the value of the step-response?

I cannot figure out how to interpret it, but if I look at the paper https://ngwa.onlinelibrary.wiley.com/doi/full/10.1111/gwat.12925 (explanation after figure 5) then it seems I could interpret it like this:

In the case below, for the recharge, can we say that if there is 1mm/d of recharge continuously the groundwater levels will reach a head of aprox 1.5m (or is it a change?) after 2000 days? or is it 3000 days or more? and for the wells, can we say that if we pump 1m3/d all the time, the head will drop 0.01m after aprox 100 days?
but I am not sure this is correct.

could you help?

Thank you very much!

[FransSchaars]

Hi @martafaneca,
Thank you for your question.
The response function is the basic building block of time series analysis.
You might want to read this article: Solving Groundwater Flow Problems with Time Series Analysis: You May Not Even Need Another Model.
Your interpretation is right, but the step respons is change in head caused by a unit change in the stress.
You can find the final change (called gain) denoted by parameter _A in the parameter list (model.parameters) in the model.plots.results() figure. To get the entire step response use model.get_step_response(). See for instance the example Notebook: https://pastas.readthedocs.io/en/master/examples/changing_responses.html.

[martafaneca]

Thank you very much for the swift answer!