Highway ditches system

[Borys]

I am trying to model the hydraulics of highway ditches system.
Problem is that my subbasin length is the same as channel length; I have no inflow except lateral flow created by road, and I need to see what flow will be in the ditch.

I created open channel presenting median of highway including left and right lanes and shoulders. How I need to tie-in subbasin to have lateral flow?

Or is there any other way to do it?

[Chris Maeder]

I reviewed your model and found that the subbasin was not connected to an outlet junction. In addition, the junction maximum (rim) elevation was defined equal to the junction invert elevation. In addition, you had a detention pond curve defined but there was no detention pond and so I deleted the detention pond curve. I was able to run the revised model (attached) for the 50 year storm and now there is flow in the ditch.

See the attached (revised) model.