MODFLOW (USGS Modular Groundwater Flow Model)
Criterion | Explanation |
General Description | MODFLOW simulates groundwater flow using a finite difference equation solution to the groundwater flow equation. |
Model Domain | The physical domain of the model includes the unsaturated and saturated zones. |
Developer | US Geological Survey |
Hardware computing requirements | The code has been used on UNIX-based computers and personal computers running various forms of the Microsoft Windows operating system. |
Code language | FortranFORTRAN. The most recent version, MODFLOW 6 was programmed in Fortran FORTRAN using a modern programming style. Many of the simulation components were programmed using an object-oriented design described in Adams and others (2009) provides a comprehensive description of the details for implementing object-oriented programming concepts using FortranFORTRAN. The object-oriented design is different from the procedural program design that was used for previous MODFLOW versions. |
Original application | The original MODFLOW model was developed in 1984 to simulate groundwater flow using a finite difference equation solution to the groundwater flow equation. It used a modular framework in which independent subroutines (modules) which simulate different features of the hydrologic system. |
Public/proprietary and cost | Public, no cost |
Physically or empirically based | Physically based |
Mathematical methods used | MODFLOW solves the groundwater flow equation using a finite-difference numerical solution. |
Input data requirements | Hydraulic conductivity, storativity, boundary fluxes (recharge, lateral fluxes), boundary conditions (constant head, head-dependent boundary, etc.) |
Outputs | Outputs include spatial distribution of heads, water budgets, and boundary flows. |
Pre-processing and post-processing tools | Multiple pre-and post-processing programs can be used with MODFLOW. These include Visual MODFLOW (Waterloo Hydrogeologic), Groundwater Vistas (Rockware), USGS Model Muse and Model Viewer. |
Representation of uncertainty | Uncertainty is represented through the results of sensitivity analysis which can be used to provide ranges of model outputs. |
Prevalence | Of all the groundwater flow models widely available, MODFLOW, is regarded by many as the most widely used by government agencies and consultant firms (Loudyi et al. 2014). |
Ease of use for public entities | There is a high level of use ease. The code is readily available for free. Training and support are readily available. Multiple graphic interfaces are available. |
Ease of obtaining information and availability of technical support | There is substantial online information available through the USGS. The USGS continues to support MODFLOW with upgraded models and addition additional features. User groups exist. Support is provided at the USGS for correcting bugs and clarification of how MODFLOW 6 is intended to work. Only limited assistance can be provided for applying MODFLOW 6 to specific problems by emailing modflow@usgs.gov or by contacting Chris Langevin, Joe Hughes, or Ned Banta at: |
Source code availability | The source code is available for modification if needed at https://water.usgs.gov/ogw/modflow/MODFLOW.html#related |
Status of model developmentWhether the model is developed and available for immediate use; this may include models that continue to be updated. What is the future direction of model updates? | MODFLOW has evolved since its initial release. Modules have been added. Examples include integration with surface-water and watershed models, addition of the unstructured grid package, explicit modeling of unsaturated-zone flow and development of the farm processes package. |
Uses in Delta | MODFLOW has been used in the Delta to simulate groundwater hydrologic conditions for the entire Delta (CVHM-D) to simulate groundwater resources impacts analysis for the BDCP EIR/EIS, and individual islands (e.g. Deverel et al. 2017). |
Challenges for integration | For integration with surface water modeling, temporal and spatial scales and calculations associated with MODFLOW modeling are different that those used for surface water models. |
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Adams, J.C., Brainerd, W.S., Hendrickson, R.A., Maine, R.E., Martin, J.T., and Smith, B.T., 2009, The Fortran 2003 handbook—The complete syntax, features and procedures, Springer Science + Business Media, 713 p., accessed Accessed June 27, 2017, at https://doi.org/10.1007/978-1-84628-746-6.
Deverel, S. J, Leighton, D. A, Lucero, C., & Ingrum, T. (, 2017). , Simulation of Subsidence Mitigation Effects on Island Drain Flow, Seepage, and Organic Carbon Loads on Subsided Islands Sacramento–San Joaquin Delta. San Francisco Estuary and Watershed Science, 15(4). Retrieved from https://escholarship.org/uc/item/4q340190.
Loudyi, Dalila; Falconer, Roger; and Lin, Binliang, 2014, "MODFLOW: An Insight Into Thirty Years Development Of A Standard Numerical Code For Groundwater Simulations" (2014). , CUNY Academic Works.
, http://academicworks.cuny.edu/cc_conf_hic/168.
See https://en.wikipedia.org/wiki/MODFLOW for summary and history.