HEC RAS Model with pipe in cross section

[NolanN]

I have a project where there is a T intersection of two roads. There is a pipe that pics up the water for normal situations and carries it downstream along the north side of the road. In a high flow situation the water exceeds the capacity of the pipe and overtops the street and runs into a ditch along the south side of the road.

So my question is do I use a junction to split the flow? Is there a way to model a pipe or culvert that passes through multiple cross sections?

 

[gbam]

I am not sure, but I do not think that the current HECRAS can model this situation. Weir flow from the culvert scenario is placed at the downstream segment. In the older versions of HECRAS I had to evaluate the weirflow externaly to determine the amount of weir flow being diverted. You may want to try to evaluate with a rating curve; but, it would still need to be computed externally of HECRAS. Maybe there is someone else that has found a way to model this in one HECRAS model.

 

[RWF7437]

NolanN,

Can you post a sketch, or two ?

 

[NolanN]

Splitting the flow and figuring out how much flow goes to each side looks like my only option right now. Unless someone else has a solution.

I provided a quick sketch of the situation

 

[RWF7437]

Some dimensions, a North Arrow, a graphic scale, a direction of flow !, some indication of the roadway sections, the flow or flows to be analysed, cross sections of both the upstream and downstream reaches, the length of the "culvert", and estimates of Manning's "n" for the channels and overbank areas would all be needed before HEC-RAS, or anyone else can answer your question.