AutoCAD Civil 3D and HEC-RAS

From AutoCAD Civil3D

Exporting Data to HEC-RAS:

1. Prepare the data in your drawing:
• Bring in the surface for the existing grade of the ground in and around the stream.
• Define the centerline (CL) of your stream with an alignment in your drawing with the stationing increase downstream.
• Create a sample line group at the desired intervals of the alignment. Be sure they do not extend beyond the extents of the surface.
• Optional: Create alignments or polylines that represent the top of bank (TB) and bottom of bank (BB).
2. Export the data as a GEO file:
• OUTPUT TAB>EXPORT PANEL>Select EXPORT to HEC RAS
• Select the surface you want for the stream sections.
• Select the site that contains the CL alignment. If it is not in a site, select <None>.
• Select the alignment that represents the CL.
• Select the Sample Line Group that contains the sections you want to export.
• Enter a name for the river/reach. This will be the name of the GEO file and the label for the stream in the HEC-RAS Geometric Data Window.
• Select the river banks if you prepared them:
• The bank locations appear in the HEC-RAS application as red dots on the sections.
• The left and right bank locations tell HEC-RAS where the Manning’s n values change for left, channel, and right bank situations in the section.
• This effects the calculations and the level of water in the section.
• The Bank Positions exported to the GEO file are measured as percentages of the overall section length rather than as offset distances.
• Click Export.
• Select where you want to save the file, enter a name and click save.
• Click OK to exit the Export to HEC RAS dialog box.

Reference

Importing Data to HEC-RAS:

1. Start the HEC-RAS Software.
2. Click Edit>Geometric Data.
3. In the Geometric Data dialog box, click File menu>import Geometric Data>GIS Format.
4. In the Import GIS Format Data File dialog box, navigate to and select the GEO file you exported from AutoCAD Civil 3D. Hit OK.
5. In the Import Geometry Data wizard, confirm the import geometry data and click Finish - Import Data. The geometry will be visible in the Geometric Data window.

Reference

From HEC-RAS

Export Data from HEC-RAS:

1. Complete your analysis in HEC-RAS.
2. In the main HEC-RAS window, click File menu>Export GIS Data.
3. In the GIS Export dialog box:
• Under Results Export Options, select Export Water Surfaces
• Select any profiles you may have created during the analysis.
4. Click Export Data. A SDF file is created.

Reference

Importing Data from HEC-RAS:

1. In AutoCAD Civil 3D, open the drawing that you exported the GEO file from.
2. INSERT TAB>IMPORT PANEL>Import HEC-RAS
3. In the Import HEC RAS dialog box, select the Site For Reach Alignment.
• If no sites exist in the drawing, then a new site named "RASimport" is selected and will be created.
• The stream alignment is imported into the drawing only if an alignment of the same name does not already exist in the site you specify.
• Existing alignments of the same name and site are not overwritten.
• Line objects that represent the sections are only imported if the alignment is imported.
4. Select the Style For Reach Alignment.
5. Select the Alignment Label Style Set.
6. Select the Profile Style.
7. Select the Profile Label Style Set.
8. Under SDF To Import, click the browse button and select the SDF file you exported from the HEC-RAS application.
9. Click Open.
10. In the Import HEC RAS dialog box, select the stream to import.
• When you select a stream, the number of profiles and sections that exist for that stream are shown in the dialog box. 
• The profiles are imported as AutoCAD Civil 3D profile objects. You must create a profile view in the drawing to view them.
• Existing profiles of the same name inside the same alignment WILL be overwritten. This is designed to allow multiple iterations within the HEC-RAS application without having to manually delete profiles in AutoCAD Civil 3D when you bring in updated data.
• The section data is imported as line objects along the alignment. These lines show where the top water surface intersects each section (according to the HEC-RAS application). They are created on layers using the convention <alignment name> - <profile name>. The section lines are imported only if the alignment is imported.
11. Click Import.
12. The flood elevation profiles are imported into the drawing and are visible in Prospector.
• If an alignment of the same name and site, as the selected stream alignment, does not already exist in the drawing, then it and the section lines are also imported.
• Section lines are not imported if the alignment is not imported.
13. Click OK.

Reference