Split flow modeling - roadside ditch and culvert

[msengelen]

I'm trying to determine if there is a good way to use Hydrocad model split flow flow for the following described conditions.

Existing condition: There is a roadside ditch and a culvert crossing under the roadway. The roadside ditch contributes flows to the culvert and the ditch continues along the roadway past the culvert. I need to determine the amount of the split flows in each direction, through the culvert and through the ditch.

Proposed condition: Same as above, except a driveway and culvert is proposed just downstream of the existing culvert. I need to determine the amount of the split flows in each direction, through the existing culvert and through the proposed culvert.

Does someone have a good idea on how to model this?

 

[psmart]

To model a flow split between two culverts you would set the routing for one culvert to primary and the other to secondary. Same for the ditch/culvert split, modeling each with the appropriate outlet device.

You can also use a link to model a flow split according to a specified flow threshold and/or flow ratio. But using primary/secondary routing is generally preferred. For details see

http://www.hydrocad.net/diversion.htm

Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[msengelen]

Thanks for your reply. I modeled the proposed condition per your reply by routing for one culvert to primary and the other to secondary, and that worked fine. However, I am still not sure how to model the existing condition with the ditch and the culvert. How should I use a pond to model this (or should I use something other than a pond)? What are your thoughts on how to model the existing condition?

 

[psmart]

You would need to use a pond for the primary/secondary option. Even a zero-storage pond would work. For the ditch scenario you could model the ditch flow using a special outlet, a weir, or the new reach outlet added in HydroCAD 10.1


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[msengelen]

Thank you.