I am using AutoCAD to model a stream and then using the Export to HEC RAS tool to export the geometry to HEC RAS. I know about the workarounds for fixing the reach and cross section directions, so that I not my problem.
I am exporting the river banks with the geometry by checking the left and right boxes, and I have alignments drawn along the river banks. But when I import the geometry into HEC-RAS, the left bank and right bank are not where I had drawn them. In areas where I drew the bank alignment along an obvious top of bank in AutoCAD, the bank station appears in HEC-RAS at the bottom of the channel or much further up the side of the overbanks.
The AutoCAD help menu for this tool has a note which says “The Bank Positions exported to the GEO file are measured as percentages of the overall section length rather than as offset distances.”
It appears as if there is an issue with this percentage calculation. Does anyone have a workaround for this issue? Perhaps a method for drawing cross sections and bank alignments which minimizes this issue?