flopy

flopy is a skill for Claude Code, Codex from SteadfastAsArt/geoscience-skills. It costs 52 tokens per session (734 once invoked), scanned A, original, MIT.

A Python interface for building, running and inspecting MODFLOW groundwater-flow models. MODFLOW is a numerical simulator for water movement through aquifers; running a model also requires a compatible MODFLOW executable.

In plain words
What is it for?
Use it to create MODFLOW 6 simulations, define aquifer layers and stresses, run groundwater-flow models, inspect hydraulic heads, and check water budgets and solver output.
Why use it?
It helps expose errors in layers, units, boundaries, pumping, recharge and water budgets before results are trusted. It also distinguishes groundwater head, which is elevation relative to a datum, from a depth measured down a well.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create MODFLOW 6 simulations, define aquifer layers and stresses, run groundwater-flow models, inspect hydraulic heads, and check water budgets and solver output.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/steadfastasart/geoscience-skills/flopy
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add SteadfastAsArt/geoscience-skills --skill flopy
Clone the repo
git clone --depth 1 https://github.com/SteadfastAsArt/geoscience-skills

Made for: Claude Code, Codex.

Its marketplace also offers this one on its own, as the plugin flopy — /plugin install flopy after adding the marketplace above.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for flopy

README.md
[![agentmods](https://agentmods.dev/badge/skills/steadfastasart/geoscience-skills/flopy/github.svg)](https://agentmods.dev/skills/steadfastasart/geoscience-skills/flopy)
Your own site
<a href="https://agentmods.dev/skills/steadfastasart/geoscience-skills/flopy"><img src="https://agentmods.dev/badge/skills/steadfastasart/geoscience-skills/flopy/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for flopy

Your own site · 80×15
<a href="https://agentmods.dev/skills/steadfastasart/geoscience-skills/flopy"><img src="https://agentmods.dev/badge/skills/steadfastasart/geoscience-skills/flopy.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 734 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00052 $0.00734
Opus 5.5 $0.00021 $0.00294
Sonnet 5.5 $0.00010 $0.00147
Haiku 4.5 $0.00005 $0.00073

Measured 1mo ago against content hash 5f10cc466ec0, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

flopy scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/confined_flow.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

flopy/SKILL.md · 68 lines

How it starts

The opening of the file, as written. The whole thing — 68 lines — stays where its author put it; the contents beside it link to each section on GitHub.

FloPy

Produce a reproducible groundwater model and a checked water budget. FloPy writes and reads MODFLOW files; solving also requires a compatible MODFLOW executable.

Inputs and choices

  • Establish horizontal CRS, vertical datum, length/time units, layer tops/bottoms, active cells, hydraulic properties, stresses and observation uncertainties.
  • Head is an elevation relative to a datum. Depth below a well collar must first be converted with the collar elevation; a LAS depth curve is not a head series.
  • Choose steady or transient conditions from the question and stress history. Distinguish hydraulic conductivity (length/time), transmissivity (length²/time), recharge (length/time) and pumping (length³/time; extraction is negative).
  • Keep MODFLOW 6 packages separate from older MODFLOW model/package APIs. Use an isolated project environment and record the executable version and origin.

Workflow

  1. Audit geometry, layer ordering and boundary coverage before assigning values.
  2. Build the simulation, temporal discretization, solver, flow model and packages. Specify convertible/confined cells deliberately, with storage for transients.
  3. Write inputs, run the declared executable, and fail if it reports failure.
  4. Inspect head/budget files and listing convergence; mask dry/inactive sentinel values before statistics. Do not treat a successful process as calibration.
  5. Compare observations with uncertainties, inspect budget discrepancy and run grid/time-step sensitivity. Hold out wells or periods before tuning parameters.

Small executable benchmark

Run scripts/confined_flow.py in an empty output folder:

python confined_flow.py --workspace ./flow-check --exe /path/to/mf6

The script models a synthetic confined strip: 11 cells, each 10 m long and 10 m wide, 20 m thick, K = 1 m/day, with fixed heads of 10 and 9 m at the end cell centres. The 100 m separation implies a linear head profile and a flow of 2 m³/day. The layer spans elevations -20 to 0 m relative to an arbitrary local datum, so both imposed heads are above the aquifer top. It checks the head profile and flow against actual MODFLOW output. No recharge, pumping, storage or heterogeneous calibration is implied by this benchmark.

Read the full file on GitHub · 68 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 68 lines · 52 tokens per session scan A 5f10cc466ec0

Subscribe to this mod's changes

flopy is a skill published in the GitHub repository SteadfastAsArt/geoscience-skills (70 stars, last pushed 1mo ago), licensed MIT. It adds 52 tokens to every session and 734 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-16.

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