Irrigation control in CLM BGC

[Arup]

Dear all,
I am a new researcher working in the field of CLM BGC modeling, with a particular focus on studying the multiple roles of irrigation. I am seeking guidance on how to implement control over irrigation within the model. Specifically, I would like to apply a control rule or mechanism for managing irrigation processes.
Could anyone kindly advise me on whether this is possible, and if so, suggest potential approaches or resources that could assist in this?

Thanks for your supports
Arup

 

[slevis]

Please read the documentation for how the model works and how to use it, including specifically regarding the irrigation:

Welcome to the CTSM documentation for CLM5.0 (CESM2.1) — ctsm release-clm5.0 documentation

 

[Arup]

I have gone through both the documentation. I intend to irrigate the crop field with merely 10% of the quantity required to achieve field capacity, instead of fully irrigating to that extent. Which variable must I modify to get this objective? I suspect it may be the 'tuning parameter (f_thresh),' but could you kindly verify its accuracy?

One general query: Is CESM2.2.z not scientifically supported for running BGC-CROP simulations? Should I use CESM2.1.z for BGC-CROP, or is it acceptable to use CESM2.2 if I am only using CLM5?

 

[slevis]

We use the term "scientifically supported" for model versions that we have tested to confirm that the model science behaves as intended. With other versions you may discover problems that we are not aware of. Still, it's likely that things will work fine. Ultimately you decide which version you prefer to use and you may have to experiment a bit before you converge on the version that works best for you.

You are also responsible for making science decisions regarding your research. If you do not feel confident about which variable to modify, it usually helps to run the model in some "trial-and-error" experiments, to see how the model responds.

As always community members are welcome to offer feedback and/or help.

 

[Arup]

Thank you very much for your reply! I truly appreciate your input.

I want to study the impact of irrigation and need to ensure that I can control and limit the volume of irrigation water. Could you kindly verify if my understanding is correct?

I intend to irrigate the crop field with merely 10% of the quantity required to achieve field capacity, instead of fully irrigating to that extent. Which variable must I modify to get this objective? I suspect it may be the 'tuning parameter (f_thresh),' but could you kindly verify its accuracy?

 

[oleson]

I don't see "f_thresh" in either the code or namelist....

 

[oleson]

Ok, I guess you mean f_thresh in the technical note, which corresponds to the namelist parameter irrig_threshold_fraction. So, sure, you can try modifying that.
Seems like you could also change irrig_target_smp. The code has these comments:

! Determines soil moisture threshold at which we irrigate. If
! h2osoi_liq_wilting_point is the soil moisture level at wilting point and
! h2osoi_liq_target is the soil moisture level at the target irrigation level (given
! by irrig_target_smp), then the threshold at which we irrigate is
! h2osoi_liq_wilting_point +
! irrig_threshold_fraction*(h2osoi_liq_target - h2osoi_liq_wilting_point)
! A value of 1 means that we irrigate whenever soil moisture falls below the target
! A value of 0 means that we only irrigate when soil moisture falls below the
! wilting point
real(r8) :: irrig_threshold_fraction

 

[Arup]

Thank you for clarifying the issue.