Welcome to the ParFlow User’s Manual

Reed M. Maxwell [1], Stefan J. Kollet [2], Laura E. Condon [3], Steven G. Smith [4], Carol S. Woodward [5], Robert D. Falgout [6], Ian M. Ferguson [7], Nicholas Engdahl [8], Jaro Hokkanen [9], George Artavanis [1], Benjamin West [3], Chen Yang [1], Basile Hector [10], James Gilbert [11], Lindsay Bearup [7], Jennifer Jefferson [12], Chuck Baldwin, William J. Bosl [13], Richard Hornung [4], Steven Ashby [14], Ketan B. Kulkarni [15]

Version: 3.15.0

Manual generated : Jul 16, 2026

Contents:

• 1. Introduction
  • 1.1. How to use this manual
• 2. Getting Started
  • 2.1. ParFlow Solvers
• 3. The ParFlow System
  • 3.1. Defining the Problem
  • 3.2. Running ParFlow
  • 3.3. Restarting a Run
  • 3.4. Visualizing Output
  • 3.5. Directory of Test Cases
  • 3.6. Annotated Input Scripts
• 4. Model Equations
  • 4.1. Steady-State, Saturated Groundwater Flow
  • 4.2. Richards’ Equation
  • 4.3. Terrain Following Grid
  • 4.4. Flow Barriers
  • 4.5. Overland Flow
  • 4.6. Multi-Phase Flow Equations
  • 4.7. Transport Equations
  • 4.8. Notation and Units
  • 4.9. Water Balance
• 5. ParFlow Files
  • 5.1. Main Input Files (.tcl, .py, .ipynb)
  • 5.2. ParFlow Binary Files (.pfb)
  • 5.3. ParFlow CLM Single Output Binary Files (.c.pfb)
  • 5.4. ParFlow Scattered Binary Files (.pfsb)
  • 5.5. ParFlow Solid Files (.pfsol)
  • 5.6. ParFlow Well Output File (.wells)
  • 5.7. ParFlow Simple ASCII and Simple Binary Files (.sa and .sb)
• 6. ParFlow Input Keys
  • 6.1. Input File Format Number
  • 6.2. Computing Topology
  • 6.3. Computational Grid
  • 6.4. Geometries
  • 6.5. Reservoirs
  • 6.6. Timing Information
  • 6.7. Time Cycles
  • 6.8. Domain
  • 6.9. Phases and Contaminants
  • 6.10. Gravity, Phase Density and Phase Viscosity
  • 6.11. Chemical Reactions
  • 6.12. Permeability
  • 6.13. Porosity
  • 6.14. Specific Storage
  • 6.15. dZMultipliers
  • 6.16. Flow Barriers
  • 6.17. Manning’s Roughness Values
  • 6.18. Topographical Slopes
  • 6.19. Channelwidths
  • 6.20. Retardation
  • 6.21. Full Multiphase Mobilities
  • 6.22. Richards’ Equation Relative Permeabilities
  • 6.23. Phase Sources
  • 6.24. Capillary Pressures
  • 6.25. Saturation
  • 6.26. Internal Boundary Conditions
  • 6.27. Boundary Conditions: Pressure
  • 6.28. Boundary Conditions: Saturation
  • 6.29. Initial Conditions: Phase Saturations
  • 6.30. Initial Conditions: Pressure
  • 6.31. Initial Conditions: Phase Concentrations
  • 6.32. Known Exact Solution
  • 6.33. Wells
  • 6.34. Code Parameters
  • 6.35. SILO Options
  • 6.36. Richards’ Equation Solver Parameters
  • 6.37. Spinup Options
  • 6.38. CLM Solver Parameters
  • 6.39. ParFlow NetCDF4 Parallel I/O
  • 6.40. NetCDF4 Chunking
  • 6.41. NetCDF4 Compression
  • 6.42. ROMIO Hints
  • 6.43. Node Level Collective I/O
  • 6.44. NetCDF4 Initial Conditions: Pressure
  • 6.45. NetCDF4 Slopes
  • 6.46. NetCDF4 Transient EvapTrans Forcing
  • 6.47. NetCDF4 CLM Output
  • 6.48. NetCDF4 CLM Input/Forcing
  • 6.49. NetCDF Testing Little Washita Test Case
• 7. Manipulating Data: PFTools
  • 7.1. Introduction to the ParFlow TCL commands (PFTCL)
  • 7.2. PFTCL Commands
  • 7.3. Common examples using ParFlow TCL commands (PFTCL)
• 8. Python
  • 8.1. PFTools
  • 8.2. Run script
  • 8.3. Tutorials
  • 8.4. Contributing keys
  • 8.5. PFTools API Reference
• 9. Bibliography

[1] (1,2,3)

Department of Civil and Environmental Engineering, The High Meadows Environmental Institute, and the Integrated GroundWater Modeling Center, Princeton University, Princeton, NJ, USA. reedmaxwell@princeton.edu

[2]

Institute for Bio- and Geosciences, Agrosphere (IBG-3) and Centre for High-Performance Scientific Computing in Terrestrial Systems, Research Centre Jülich, Jülich, Germany. s.kollet@fz-juelich.de

[3] (1,2)

Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, USA. lecondon@arizona.edu

[4] (1,2)

Center for Applied Scientific Computing, Lawrence Livermore National Laboratory, Livermore, CA. USA.

[5]

Center for Applied Scientific Computing, Lawrence Livermore National Laboratory, Livermore, CA, USA. cswoodward@llnl.gov

[6]

Center for Applied Scientific Computing, Lawrence Livermore National Laboratory, Livermore, CA, USA.

[7] (1,2)

US Bureau of Reclamation, Denver, CO, USA.

[8]

Civil and Environmental Engineering, Washington State University, Pullman, WA, USA. nick.engdahl@wsu.edu

[9]

CSC - IT Center for Science, Espoo, Finland

[10]

Université Grenoble-Alpes/IRD/IGE, Grenoble, FR.

[11]

University of California, Santa Cruz & NOAA Fisheries Southwest Fisheries Science Center, Santa Cruz, CA, USA

[12]

HNTB, Milwaukee, Wisconsin, United States.

[13]

Children’s Hospital Informatics Program, Harvard Medical School, Boston, MA, USA.

[14]

Pacific Northwest National Laboratory, Richland, WA, USA.

[15]

Jülich Supercomputing Centre and Centre for High-Performance Scientific Computing in Terrestrial Systems, Research Centre Jülich, Jülich, Germany.

ParFlow is released under the GNU LPGL License

This manual is licensed under the GNU Free Documentation License.

Copyright © 2024 Reed M. Maxwell, Stefan J. Kollet, Laura E. Condon, Ian M. Ferguson, Steven G. Smith, Carol S. Woodward, Nicholas Engdahl. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

This computer software and documentation was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes.