Adjust HCOF and RHS for an existing package

[cneyens]

Is it possible to adjust the HCOF and RHS coefficients of an existing boundary condition package? I've tried this using set_advanced_var at the start of the outer iteration loop, but when calling solve() the coefficients are overwritten by the CF & FC subroutines (see also #30). Is there a way to prevent the solve() procedure from overwriting the user-defined HCOF and RHS values?

I'm basically trying to switch some GHB's from a third-type boundary condition to a constant-flux based on a maximum-allowed flow rate by adjusting the matrix coefficients (so setting HCOF to zero and setting RHS to the maximum flux). Alternatively, I can follow the approach of the custom ET package as shown in the MODFLOW-API paper, but that involves setting up a 'new' package instead of adjusting the behaviour of an existing one.

[christianlangevin]

Hey @cneyens, I was trying to think of a way for you to do this, but I couldn't think of a simple answer. Other than using the API package, I think the only other way would be to specify both a wel package and a ghb package, and then toggle the well flow rate and the ghb conductance according to the behavior you want. We could probably think of a future modification for MODFLOW that would allow this, but I don't think there is one now.

[cneyens]

Thanks for the reply @langevin-usgs! I don't expect MODFLOW to handle these kind of adjustments to existing packages; that's what the API is useful for. We'll use the custom package approach with the API to do this.