A Python package to create, run, and post-process MODFLOW-based models.





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Version 3.3.5 — release candidate

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FloPy includes support for MODFLOW 6, MODFLOW-2005, MODFLOW-NWT, MODFLOW-USG, and MODFLOW-2000. Other supported MODFLOW-based models include MODPATH (version 6 and 7), MT3DMS, MT3D-USGS, and SEAWAT.

For general modeling issues, please consult a modeling forum, such as the MODFLOW Users Group. Other MODFLOW resources are listed in the MODFLOW Resources section.


FloPy requires Python 3.7 (or higher) and NumPy 1.15 (or higher). Dependencies for optional FloPy methods are summarized here.

To install FloPy type:

conda install -c conda-forge flopy


pip install flopy

The release candidate version can also be installed from the git repository using the instructions provided below.


Documentation is available on Read the Docs and includes information on FloPy; tutorials for using FloPy with MODFLOW 6 and previous versions of MODFLOW, MT3DMS, MT3D-USGS, MODPATH, and ZONEBUDGET; and code documentation.

Getting Started

MODFLOW 6 Quick Start

import flopy
ws = './mymodel'
name = 'mymodel'
sim = flopy.mf6.MFSimulation(sim_name=name, sim_ws=ws, exe_name='mf6')
tdis = flopy.mf6.ModflowTdis(sim)
ims = flopy.mf6.ModflowIms(sim)
gwf = flopy.mf6.ModflowGwf(sim, modelname=name, save_flows=True)
dis = flopy.mf6.ModflowGwfdis(gwf, nrow=10, ncol=10)
ic = flopy.mf6.ModflowGwfic(gwf)
npf = flopy.mf6.ModflowGwfnpf(gwf, save_specific_discharge=True)
chd = flopy.mf6.ModflowGwfchd(gwf, stress_period_data=[[(0, 0, 0), 1.],
                                                       [(0, 9, 9), 0.]])
budget_file = name + '.bud'
head_file = name + '.hds'
oc = flopy.mf6.ModflowGwfoc(gwf,
                            saverecord=[('HEAD', 'ALL'), ('BUDGET', 'ALL')])

head = gwf.output.head().get_data()
bud = gwf.output.budget()

spdis = bud.get_data(text='DATA-SPDIS')[0]
qx, qy, qz = flopy.utils.postprocessing.get_specific_discharge(spdis, gwf)
pmv = flopy.plot.PlotMapView(gwf)
pmv.contour_array(head, levels=[.2, .4, .6, .8], linewidths=3.)
pmv.plot_vector(qx, qy, normalize=True, color="white")

Additional FloPy Resources

  • Tutorials demonstrating basic FloPy use.

  • MODFLOW 6 Example Problems demonstrating FloPy use to create, run, and post-process MODFLOW 6 models.

  • Jupyter notebooks demonstrating the use of FloPy pre- and post-processing capabilities with a variety of MODFLOW-based models.

  • Scripts demonstrating the use of FloPy for running and post-processing MODFLOW-based models.

  • A list of supported packages in FloPy is available in docs/supported_packages.md on the github repo.

  • A table of the supported and proposed model checks implemented in FloPy is available in docs/model_checks.md on the github repo.

  • A summary of changes in each FloPy version is available in docs/version_changes.md on the github repo.


FloPy usage has been growing rapidly, and as the number of users has increased, so has the number of questions about how to use FloPy. We ask our users to carefully consider the nature of their problem and seek help in the appropriate manner.

Do not open issues for general support questions as we want to keep GitHub issues for bug reports and feature requests. You've got much better chances of getting your question answered on Stack Overflow where the questions should be tagged with tag flopy or the MODFLOW google group.

Stack Overflow is a much better place to ask questions since:

  • there are thousands of people willing to help on Stack Overflow and the MODFLOW google group
  • questions and answers stay available for public viewing so your question / answer might help someone else
  • Stack Overflow's voting system assures that the best answers are prominently visible.

To save your and our time, we will systematically close all issues that are requests for general support and redirect people to Stack Overflow or the MODFLOW google group.


Bug reports, code contributions, or improvements to the documentation are welcome from the community. Prior to contributing, please read up on our guidelines for contributing and then check out one of our issues in the hotlist: community-help.

Installing the latest FloPy release candidate

To install the latest release candidate type:

pip install https://github.com/modflowpy/flopy/zipball/develop

How to Cite

Citation for FloPy:

Bakker, Mark, Post, Vincent, Langevin, C. D., Hughes, J. D., White, J. T., Starn, J. J. and Fienen, M. N., 2016, Scripting MODFLOW Model Development Using Python and FloPy: Groundwater, v. 54, p. 733–739, doi:10.1111/gwat.12413.

Software/Code citation for FloPy:

Bakker, Mark, Post, Vincent, Hughes, J. D., Langevin, C. D., White, J. T., Leaf, A. T., Paulinski, S. R., Bellino, J. C., Morway, E. D., Toews, M. W., Larsen, J. D., Fienen, M. N., Starn, J. J., and Brakenhoff, Davíd, 2021, FloPy v3.3.5 — release candidate: U.S. Geological Survey Software Release, 20 August 2021, http://dx.doi.org/10.5066/F7BK19FH

MODFLOW Resources


This software is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The software has not received final approval by the U.S. Geological Survey (USGS). No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the functionality of the software and related material nor shall the fact of release constitute any such warranty. The software is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the software.

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