This stream has its narrower bank on the left, imported correctly. Sections run left to right (looking downstream) and your banks are in In the Geometric Data, View, View Options, Cross Section PropertiesĪrea, turn on the XS Direction Arrows check box. Then paste the resulting list (no reversing needed) back into the Cross Sections and IB Nodes, Import As column. Use spreadsheet to fix cross section River Stations You may want to copy the stations to a LibreOffice (Go, Free/Libre Open Source Software!) spreadsheet, and subtract each River Station from the highest River Station. They will increase from upstream to downstream, which will make HEC-RAS calculate your stream backwards.
If you want, use the tools in the Cross Sections and IB Nodes tab to assign river stations to the sections, but DO NOT import yet. Rename cross sections to increase going upstream.When you get to the Cross Sections and IB Nodes, STOP. to import the Civil-3D-geometry-export you created. In the HEC-RAS Geometry Data editor, use File, Import Geometry Data., GIS Format.The finished sample lines should all start on the left and run to the right. After you select the alignment, a toolbox appears where you can choose to create the sample lines from polylines. They should cross (not end at or short of) the centerline. We will address the downstream to upstream hydraulic calculations later. Having it point downstream is important so that the cross sections and banks read correctly from left to right looking downstream. Create a Civil 3D alignment from the polyline, and use the Reverse Alignment Direction tool if necessary so that the stations increase going downstream. Draw a stream alignment polyline (direction is not important). Start with a ground surface that completely encompasses both the river alignment and the cross sections. But the general idea works with earlier Civil 3D and HEC-RAS 4. Note: These were written toward Civil 3D 2016 and HEC-RAS 5.