To Export Data to HEC-RAS Format

Use the Export To HEC-RAS command to export Autodesk Civil 3D surface, site, alignment, and section information for use in the HEC-RAS software.

1. Prepare your drawing data.
2. Click Output tabExport panelExport To HEC RAS Find.
3. In the Export To HEC RAS dialog box, for Surface, select the surface you want to sample for the ditch sections.
4. For Site, select the site that contains the ditch centerline alignment, or select <None> if the alignment is not located in a site.
5. For Reach Alignment, select the alignment that represents the ditch centerline.
6. Select the Sample Line Group that contains the sections you want to export.
7. Enter a River Name. This should typically be the name of the ditch alignment. This name is used in the HEC-RAS application as the title of the GEO file and is used as a label for the ditch in the HEC-RAS Geometric Data window.
8. To export river bank information, select Check This To Use River Banks, click Left and/or Right, and select the polylines or alignments in the drawing.
   Note: 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, drainage 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.
9. Click Export.
10. In the Export Data To GEO File dialog box, navigate to the location where you want to save the GEO file.
11. Enter a File Name. Click Save.
12. Click OK to exit the Export To HEC RAS dialog box.
13. Follow the steps in To Import Data into and Export Data from HEC-RAS Software.