HEC-RAS Custom Culvert

Chris,

I have a quick question about modeling a culvert in RAS. Is it possible to put in a custom culvert if it is not one of the nine options (i.e. circular, box, arched, etc) in the culvert data editor dialog box? I'm working on a project that has an odd shaped culvert and was wondering how this could be done. Any ideas would be great!

Rob Schurman, EIT | Water Resource Engineer
Entrancoz

Dear Rob :

The only way that you can model a custom shaped culvert is to either determine the rating curve for the culvert externally and then use that to define the head loss from the upstream cross section to the downstream cross section, or to model it as a bridge opening with the shape of your custom culvert.

If you have any additional questions or need any further information, please contact me again.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com

Thanks Chris,

Would I add the rating curve to the upstream or downstream cross-section? I think it should be the upstream cross-section but I just want to verify.

Rob Schurman, EIT I Water Resource Engineer
Entranco

Dear Rob :

The backwater would be created upstream of the culvert. So, I would define it at the upstream face cross section.

If you have any additional questions or need any further information, please contact me again.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com

[Chuck Moore]

I assume that you enter the rating curve as an "Internal Rating Curve" option for the cross-section. Does this work for unsteady HEC-RAS. It seems to be very unstable when I try it