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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 mesh geometry so it can be imported into HEC-RAS.


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

  • *.g01 – HEC-RAS geometry file.
  • *.g01.hdf
  • *.prj – The HEC-RAS projection file. For post-processsing, open this file in the HEC-RAS software.
  • *_projection.prj – The projection/coordinate system used by the project in SMS.

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.

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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