Thursday, October 16, 2014

Re-Projecting HEC-RAS Model Geometry

Written by Sarah Bengtson  |  WEST Consultants
Copyright © The RAS Solution 2014.  All rights reserved.

HEC-RAS 5.0 now provides a tool for quickly re-projecting model geometry within RAS. It is accessible from the main RAS interface under the Options menu…Convert Horizontal Coordinate Systems.


From this window, the user must select the Current Project Spatial Reference System and the Destination Project Spatial Reference System by loading the appropriate projection file (*.prj) for each. Do not confuse this file type with an HEC-RAS project file (also *.prj).  Once the projection files are loaded, click OK.


A warning window will appear alerting you that running this tool will automatically save the data to disk. If you do not wish to overwrite your existing RAS project files, click cancel, save the project as a new name, and convert the duplicate project. Otherwise, click OK.



  1. Hi Chris,

    Do you know if there is a way to determine a HEC-RAS model's projection/spatial reference system when we were not told?

    Derek Chang

    1. Derek- Give this a read and see if it helps:

      Essentially it requires some trial and error work. Experience working with projections will speed up the process.

      Good luck-

  2. Hello, I get the following error when I convert project coordinates. Do you know of a way I can resolve this error? THanks

    Warning - An error occured in geometry data SRS conversion.

  3. Hi JC, I got the same error, but it converted the projection anyway! You might see if it worked despite the error.

  4. when i do that it appear error in saving file alrady open how i solve this problem

  5. Chris,

    Question about unit change of HEC-RAS. We know HEC-RAS has two units (i.e., feet or meter), so people can choose which one to use.

    Here is a unique situation. We have a HEC-RAS model used in the Souris River System which covers both Canada and US; the model is calibrated by Army Cops of Engineers in unit of feet. Then we in Canada want to use this model, but our unit here is meter for flow, lake level, and discharges.

    So can we simply change the unit to meter in HEC-RAS, and have our inputs with this model? Or we need to have our inputs converted to feet, then to feed inputs into this model? I feel that latter makes more sense. What is your thought?



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