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The Hydrologic Engineering Center's River Analysis System (HEC-RAS) is a one- and two-dimensional model for computing water surface profiles for steady state or gradually varied flow. HEC-RAS supports networks of channels and is capable of modeling subcritical, supercritical, and mixed flow regime profiles. HEC-RAS is able to model obstructions in the flow path. Two dimensional capabilities were added to HEC-RAS 5.0 in 2016.

Historically, SMS and WMS have supported tools for creating and editing cross sections and attributes for these cross sections for one dimensional HEC-RAS 1D. These cross sections can be imported from the HEC-RAS system in the form of an SDF file (exported by HEC-Ras) and saved as a HEC-GeoRAS file for inclusion into a HEC-RAS project. The WMS package has also developed floodplain mapping tools to generate floodplains from HEC-RAS results.

With the 2D version of HEC-RAS, a new SMS interface to HEC-RAS has been added (starting with SMS 12.2). This new interface is a simulation-based interface that allows defining multiple simulations with individual settings in a single SMS project. All of the mesh generating options supported in the SMS may be used to generate/edit a grid for use in HEC-RAS 2D.

SMS continues to include tools for defining river networks and cross-sections.

The HEC-RAS model can be added to a paid edition of SMS.

HEC-RAS Simulation

Example of a HEC-RAS simulation in the Project Explorer

Starting in SMS 12.2, HEC-RAS uses a simulation process. SMS can run multiple HEC-RAS simulations using the same components. To create a new simulation, right-click in the Project Explorer and select New Simulation | HEC-RAS. Components can then be linked to simulations by dragging the components under the simulation or by right-clicking on the component item and using the Link To submenu.

Components for the HEC-RAS simulation include the following:

  • 2D Mesh

HEC-RAS Simulation Menu

Right-clicking on a HEC-RAS simulation provides a menu with the standard simulation menu commands and the following commands specific to HEC-RAS:

  • Model Check – Launches the model checker to look for problems with the simulation setup.
  • Export HEC-RAS – Exports the *.rasgeo file containing the mesh information that will be converted during the simulation run.
  • Launch HEC-RAS – Brings up the HEC-RAS model wrapper and starts the simulation run. At the end of the simulation run, HEC-RAS will have created a number of output files for use in the HEC-RAS program.
  • Save, Export, and Launch HEC-RAS – Completes the processes of saving the SMS project, exporting the HEC-RAS files, and launching the HEC-RAS simulation run.


A HEC-RAS simulation in SMS can generate a number of files for use in the HEC-RAS program. The following files are generated:

  • *.rasgeo – Contains the mesh data generated in SMS. This file is used to generate the other files and must be created before running the HEC-RAC simulation.
  • *.g01 – HEC-RAS geometry file.
  • *.g01.hdf
  • *.prj – The HEC-RAS projection file. For post-processsing, open this file in the HEC-RAS software.


The RASGEO file contains unit, element, and node information from the mesh component in the HEC-RAS simulation.

GridUnit "METER"
Elem 1 2 4 1
Elem 2 2 5 4
Elem 3 4 6 3
Elem 4 4 7 6
Elem 5 7 4 5
Elem 6 6 7 19
Elem 7 6 19 9
Elem 8 7 8 19
Elem 9 20 8 10
Elem 10 8 20 19
Elem 11 22 9 21
Node 1 412266.749188 2048559.109411 0.000000
Node 2 412293.104804 2048577.696988 0.000000
Node 3 412206.837470 2048630.299699 0.000000
Node 4 412235.340370 2048594.711214 0.000000
Node 5 412292.972567 2048627.616721 0.000000
Node 6 412234.872220 2048666.466041 0.000000
Node 7 412264.180764 2048663.798224 0.000000
Node 8 412281.643700 2048705.121722 0.000000
Node 9 412214.903435 2048704.060367 0.000000

HEC-RAS Troubleshooting

Starting in SMS 12.2, HEC-RAS uses the dynamic model interface. If HEC-RAS was purchased through Aquaveo, the DMI file and HEC-RAS library was included in the installation and should be available for use when starting SMS.

If installing HEC-RAS to an existing version of SMS 12.2 or later, the XML file must be placed in the DynamicXml directory inside the SMS program directory. HEC-RAS also requires a translator. The RAS2D_translator folder should be placed in the Models directory inside the SMS program directory.

SMS needs to know the location of the HEC-RAS executable. If an error appears stating the executable cannot be found, go to Edit | Preferences to open the Preferences dialog. In the File Locations tab, set the HECRAS Translate item to point to the "_runRunGeneric.bat" file in the RAS2D_tranlator.

Currently, HEC-RAS will encounter a memory error when exporting a mesh that contains more than 500,000 elements.

HEC-RAS does not support voids in a mesh. Be certain to review the mesh for voids, holes, flat elements, and other irregularities before exporting.

Related Topics

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