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Water Software > Groundwater Software > MODFLOW and Related Programs > SWR

Surface-Water Routing (SWR) Process for Modeling Surface-Water Flow with the USGS Modular Groundwater Flow Model (MODFLOW)

Overview of the SWR Process

[Image: Cover of software documentation report. ]

The Surface-Water Routing (SWR) Process was developed to accurately simulate stages, surface-water flows, and surface-water/groundwater interactions in areas where surface-water gradients are small and (or) there is significant management of surface water. A simplified form of the Saint-Venant equations was implemented in the SWR Process based on assumption requirement that it will be applied to continuous simulations (hourly to daily time steps) in support of water-resource planning activities. As a result, the SWR Process was not intended as a replacement for hydrodynamic models that solve the full Saint-Venant equations and are applied to event simulations (sub-hourly time steps).

The SWR Process uses a flexible approach for simulating one- and two-dimensional routing of surface-water flow. The SWR Process is implicitly coupled to the Groundwater Flow Process in MODFLOW. Surface-water routing in SWR can be simulated using a diffusive-wave approximation of the vertically-integrated Saint-Venant equations and/or a simplified level-pool approach. SWR can account for surface-water flow controlled by backwater conditions caused by small water-surface gradients or surface-water control structures. A number of typical surface-water control structures (such as culverts, weirs, and pumps, for example) can be represented, and simple operational rules can be specified to manage surface-water stages and streamflow by moving water from one surface-water feature to another. The non-linear surface-water flow equations implemented in the SWR Process are solved using Newton methods and direct or iterative solvers.

The SWR Process uses the familiar structure of MODFLOW-2005 and the MODFLOW concepts of "packages" and "processes" are retained. This permits versions of MODFLOW-NWT and MODFLOW-2005 that include the SWR Process to work with many of the MODFLOW-related software programs, such as MODPATH, ZONEBUDGET, and parameter estimation programs. MODFLOW-NWT and MODFLOW-2005 with the SWR Process are public domain computer programs. The source code and software are distributed free of charge by the USGS.

SWR Information and Downloads

SWR History

  • SWR Release Notes [5KB TXT]
  • History Version 1.0, released 09/21/2012: This is the original SWR version as documented in Hughes and others (2012).
  • Version 1.01.0, released 10/17/2012: The SWR Process was modified to allow incorporation of SWR derivative terms into the groundwater flow equation solved by MODFLOW-NWT. The SWR Process was also modified to allow downstream discharge from a SFR2 reach to be routed to a SWR reach using an additional type of SWR surface-water control structure. The SWR Process was also modified to allow surface-water control structures discharging from the SWR network to discharge to SFR2 reaches. SWR Version 1.01.0 is also included in the version of MODFLOW-2005 available in the "Superseded Versions" section of this page.

SWR Process users are encouraged to use the version incorporated into MODFLOW-NWT, even if the features of MODFLOW-NWT are not required for a particular application.


Documentation of SWR

Hughes, J.D., Langevin, C.D., Chartier, K.L., and White, J.T., 2012, Documentation of the Surface-Water Routing (SWR1) Process for modeling surface-water flow with the U.S. Geological Survey Modular Ground-Water Model (MODFLOW-2005): U.S. Geological Survey Techniques and Methods, book 6, chap. A40 (Version 1.0), 113 p. Available online at

Superseded Versions

Note: these versions are no longer actively supported or maintained

Example Applications of the Surface-Water Routing Process

Hughes, J.D., and White, J.T., 2014, Hydrologic conditions in urban Miami-Dade County, Florida, and the effect of groundwater pumpage and increased sea level on canal leakage and regional groundwater flow: U.S. Geological Survey Scientific Investigations Report 2014-5162, 175 p.,

Hughes, J.D., Langevin, C.D., and White, J.T., 2014, MODFLOW-based coupled surface-water routing and groundwater flow simulation: Ground Water,

Point of Contact

Support is provided for correcting bugs and clarification of how the SWR Process is intended to work. Only limited assistance can be provided for applying the SWR Process to specific problems by contacting the point of contact listed below:

Joseph D. Hughes

U.S. Geological Survey (USGS) Office of Groundwater
411 National Center
12201 Sunrise Valley Drive
Reston, VA 20192

Development of the SWR Process was funded in part by the Miami-Dade Water and Sewer Department[ Link exits USGS web site ].

Related USGS Software Resources

Other USGS Groundwater Software

The USGS develops groundwater, water-quality, surface-water, and other water-resources software for use by the USGS in fulfilling its mission. Most of this software is available online for download at no charge.

Disclaimers and Notices

This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. 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. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use. Also refer to the USGS Water Resources Software User Rights Notice for complete use, copyright, and distribution information.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

See also, USGS policy on linking to non-Federal web sites.

Software License and Purchase Information

This software is a product of the U.S. Geological Survey, which is part of the U.S. Government.


This software is freely distributed. There is no fee to download and (or) use this software.


Users do not need a license or permission from the USGS to use this software. Users can download and install as many copies of the software as they need.

Public Domain:

As a work of the United States Government, this USGS product is in the public domain within the United States. You can copy, modify, distribute, and perform the work, even for commercial purposes, all without asking permission. Additionally, USGS waives copyright and related rights in the work worldwide through CC0 1.0 Universal Public Domain Dedication ( [Link exits USGS]).

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Page Last Modified: Thursday, 29-Dec-2016 20:33:29 EST