HEC-RAS Open ditch to Storage Area modeling?

[KatieTX]

My basic question is how do I model a storage area that outfalls to a channel with no control structure?

The details:

In my detention system, I have a storage area (1) that outfalls into a channel through culverts. I am modeling this using the lateral structure option in HEC-RAS (unsteady). Downstream, the channel flows into another storage area (2), but this time it is an open connection (no embankment/culverts/control structure). How would I model that in HEC-RAS? I am thinking of using a lateral structure at the downstream end of the channel, and making the weir shape the same shape as my open channel. Would that be the most appropriate way to do it?

Storage area 2 is connected to another storage area downstream (3). These 2 are connected using culverts, and I can use a storage area connection to model that. Storage area 3 then flows into an open channel with no control structure.

 

[bltseattle]

Additional context would be helpful. What is the purpose of your modeling? WHat events are you trying to model? Is this for a floodplain analysis or for a detention design? What is the order of magnitude ratio of flow in the channel vs. flow from your detention system?

 

[KatieTX]

This is for a detention design - 100 year.

I found my answer though. It was in the Unsteady Flow example from the HEC-RAS manual all along. All I have to do is draw the storage area on the schematic, and then use the "Move Objects" command to drag the downstream end of the channel to the edge of the storage area. HEC-RAS will automatically connect them.