Add HFB package builder from dataframes

[bdestombe]

The full workflow from GeoDataFrame line features to a FloPy HFB package is implemented in nlmod, while delegating the horizontal line-to-cell routing to FloPy.

Summary

• add nlmod.gwf.hfb.hfb_from_df to build MF6 HFB packages from line GeoDataFrames
• delegate HFB line routing to flopy.utils.make_hfb_array from Feat(hfb_util): add method for creating HFBs modflowpy/flopy#2745
• keep nlmod-specific depth/elevation hydchr scaling and idomain <= 0 filtering around the FloPy-generated cell pairs
• use FloPy develop until the HFB utility from flopy#2745 is available in a release (flopy>3.10.0)
• cover default columns, scalar values, custom columns, MultiLineString input, package naming, zero-SPD cleanup, FloPy routing, and inactive/pass-through filtering in HFB tests

Validation

• python -m py_compile nlmod\gwf\hfb.py
• python -m ruff format nlmod\gwf\hfb.py tests\test_023_hfb.py
• python -m ruff check --fix nlmod\gwf\hfb.py tests\test_023_hfb.py
• python -m pytest tests\test_023_hfb.py -v
• python -m prospector nlmod\gwf\hfb.py tests\test_023_hfb.py
• bandit -q -r nlmod\gwf\hfb.py
• local availability check for flopy.utils.make_hfb_array

[dbrakenhoff]

Looks good to me!

Seeing this reminds me that flopy now has HFB logic: modflowpy/flopy#2745

So I'm not sure how robust our algorithm is, but it could be worth exploring deferring the logic for building the HFBs to flopy? And on a similar note, I at some point added the line_to_hfb_buffer method that was supposed to be more robust and faster for more complex HFBs. I don't know if I actually succeeded, but it could be worth checking out this method as well...

But feel free to open a new issue to tackle those questions :)

[bdestombe]

Looks good to me!

Seeing this reminds me that flopy now has HFB logic: modflowpy/flopy#2745

So I'm not sure how robust our algorithm is, but it could be worth exploring deferring the logic for building the HFBs to flopy? And on a similar note, I at some point added the line_to_hfb_buffer method that was supposed to be more robust and faster for more complex HFBs. I don't know if I actually succeeded, but it could be worth checking out this method as well...

But feel free to open a new issue to tackle those questions :)

Thanks for the review! And I'm all in favor, but that would require pinning flopy to something recent. Could that cause any issues with other users?

As for the linting/formatting, I'll update that. I think I was developing from a different folder so that ruff didn't pick up on the formatting configuration file.

[dbrakenhoff]

Thanks for the review! And I'm all in favor, but that would require pinning flopy to something recent. Could that cause any issues with other users?

Good question. I don't really think so since flopy mostly manages I/O and backwards compatibility is something they take very seriously.

[bdestombe]

Thanks for the pointer to modflowpy/flopy#2745. I updated this PR to use that FloPy logic instead of maintaining nlmod's own line-routing path for the new package-builder workflow.

Changes since your review:

• get_hfb_spd now delegates horizontal line-to-cell routing to flopy.utils.make_hfb_array.
• nlmod still handles the parts that FloPy does not: depth/elevation vertical hydchr scaling and explicit idomain <= 0 filtering.
• hfb_from_df remains the GeoDataFrame-to-package convenience wrapper on top of get_hfb_spd.
• The FloPy dependency now points to the develop branch, with an inline pyproject.toml comment noting that this is for the HFB utility from flopy#2745 and can move to flopy>3.10.0 once released.
• Tests now assert FloPy availability/use, structured known-answer depth/elevation scaling, vertex cell-pair agreement with direct FloPy output, MultiLineString handling, and inactive/pass-through filtering completeness.
• I also removed the stale commented-out endpoint-handling block in the legacy line_to_hfb path.

Local validation passed with FloPy develop: py_compile, ruff format/check, pytest tests\test_023_hfb.py -v, prospector, bandit, and an explicit flopy.utils.make_hfb_array import check.

[bdestombe]

As far as I can tell there is no option to disable the trailing comma in multiline calls in the ruff configuration. Apparently, this complies with the standard, but also nlmod's, formatting rules

[bdestombe]

Hi David and others,
Merging this would require nlmod to use the develop branch of flopy. I would understand this is not ideal, however:

• It would only be until the next flopy version is released (e.g., flopy version > 3.10)
• it passes the current nlmod CI, so seems stable enough

[dbrakenhoff]

Yeah, ideally we release this only when flopy releases with the hfb utils and pin nlmod to use the newest flopy? From issues on flopy I gather the next release should happen in the next 1-2 weeks, so we won't have to wait that long?

So fine by me to merge this into dev, and hold our next release (which we really should do) until flopy has made theirs.

[Copilot]

Pull request overview

Implements an end-to-end workflow for creating MODFLOW 6 Horizontal Flow Barrier (HFB) packages from line GeoDataFrames in nlmod, delegating line-to-cell-pair routing to FloPy while keeping nlmod-specific hydchr scaling and inactive/pass-through filtering.

Changes:

• Added nlmod.gwf.hfb.hfb_from_df plus supporting helpers, and updated get_hfb_spd to use flopy.utils.make_hfb_array.
• Deprecated legacy line-routing helpers (line_to_hfb, line2hfb, line_to_hfb_buffer) and updated tests accordingly.
• Switched flopy dependency to a VCS URL targeting the develop branch to access the new utility.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
nlmod/gwf/hfb.py	Adds the DataFrame-to-HFB builder, routes via FloPy make_hfb_array, and introduces deprecation warnings for legacy routing helpers.
tests/test_023_hfb.py	Adds/updates tests for hfb_from_df, FloPy routing delegation, scaling behavior, geometry handling, and deprecation warnings.
pyproject.toml	Changes flopy dependency to track FloPy develop to obtain the new HFB routing utility.

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