Optimizing the HEC-RAS Model

With an imported HEC-RAS model ready to be run in HEC-WAT, a few small steps can help reduce the overall model run times further – primarily by running the Geometry Pre-processor and saving the results prior to the compute.  The example study's HEC-RAS model contains 2D areas and require the terrain file to compute the geometry. Therefore, the terrain file will need to be added to your Russian River study folders and the HEC-RAS Geometry Preprocessor will need to be computed.

  1. From the File menu, click Save Study.
  2. From the user's computer, locate the HEC-WAT directory for the watershed. From the FRA_RR > RussianRiver_Maps folder, copy the three Terrain.* files into the ras folder to the HEC-WAT directory that contains the study. 
  3. Return to the HEC-WAT main window, from the Menu bar, click the HEC-RAS icon HEC-RAS icon to open HEC-RAS.
    HEC-RAS main window


  4. From the HEC-RAS main window, click the RAS Mapper icon RAS Mapper icon. 
  5. The RAS Mapper window opens. Right-click on Terrain in the Study Tree and select Add and Existing RAS Terrain.
    RAS Mapper, Add an Existing RAS Terrain shortcut menu command


  6. From the Select existing terrain file browser window, navigate to the ras folder and select the copied Terrain.hdf file, and click Open. The browser window closes.
  7. The RAS Mapper window updates to display the selected Russian River terrain. In the RAS Mapper window, from the File menu, click Save and Exit to close RAS Mapper.
  8. From the HEC-RAS main window, click the Unsteady Flow Analysis icon Unsteady Flow icon. The Unsteady Flow Analysis dialog opens.
    HEC-RAS Unsteady Flow Analysis dialog


  9. In the Programs to Run panel the following three items are selected:
    • Geometry Preprocessor
    • Unsteady Flow Simulation
    • Post Processor
  10. Unselect everything but the Geometry Preprocessor, and click Compute. The HEC-RAS Computations window open.
    HEC-RAS Computations Finished window


  11. When the compute finishes, click Close and from the Unsteady Flow Analysis dialog, Programs to Run panel, reselect the Unsteady Flow Simulation and Post Processor. Close the Unsteady Flow Analysis dialog.
  12. From the HEC-RAS main window, from the File menu, click Save Project and Exit to close HEC-RAS.