Dear Lee :
I have answered your questions below. Feel free to ask any others.
> 1. Can I put in multiple levees, stairsteps if you will, on the same side of the river to handle different flows?
Ummm... This is a limitation in HEC-RAS. You can only place a single levee on each side of the river. In order to model multiple levees, you would need to revise the cross section geometry to account for this.
> 2. Is it possible to flood map 2 reaches on the same drawing, like for split flows going into different channels?
Yes. I just finished a model with 2 branches. Model the first reach and generate the floodplain map. Then, WBLOCK the floodplain map to an external file. Do the same for the second reach. Then, open a new drawing file and INSERT the two wblocked blocks and then EXPLODE them. You can then manually edit the ploylines that make up the final floodplain map. It goes quite quickly. I would even rename the layer that the floodplain map is on. Finally, save this file and then INSERT this floodplain map into your original drawing file.
> 3. Is there a way, say like channel mods etc., to apply levees or
floodwalls to my drawing to see the effects on the flood mapping?
The digital terrain engine needs to be able to see the floodwalls as part of the terrain data. If it is just a HEC-RAS levee definition, then use the "Simple Floodplain Mapping" option. It will draw a straight line between cross sections, but it is a very close to the actual results.
> 4. Can 3d polylines be used etc.?
Yes. Anything 3D, even sopt elevations, points, and blocks.
> 5. When will the new XP version with Hec-Ras 3.1 be ready?
RSN (real soon now :). You can even select which version of the HEC-RAS engine you want to use (i.e., 2.2, 3.0, 3.1). It's really cool.
Sincerely,
Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com
Linear Mode
