Lateral Structure Tailwater Connection

[mlc3n3]

I am modeling a road embankment parallel to a stream with a lateral structure with culverts.

I am looking to better understand the tailwater connection input. I’ve looked at the HECRAS user manual and other resources, but I’m not finding a clear definition and suggested practice to define the tailwater connection station. Could someone explain this?

Right now I have one lateral structure and 3 groups of culverts. I was getting weird results because I defined the tailwater station at the most upstream x-sec of the lateral structure. I found a suggestion to define the tailwater station at the x-secs in the middle between culvert groups. Any idea why?
I found another suggestion to split the lateral structure into 3 different lateral structures, so each contains only one culvert group.
Further, the tailwater station for each lateral structure would be placed at the x-secs just upstream of a culvert group. Any idea why?

Also not sure how to upload screenshots on this new platform…

Thanks in advance!

[Scott Miller]

It would be helpful to see those screen shots. Are you modeling 1D/2D unsteady, or 1D with a storage area? Do the lateral structures connect to the tailwater only through the culverts, or do you expect them to be overtopped? Are you defining the lateral structure entirely in the geometry editor, or in Mapper and the geometry editor. What progress have you made since your post, and are you seeing convergence issues or volume error?

[Author]

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