HEC-RAS: existing steady model, proposed detention 2

[dlnva350]

We have an existing steady model we’re working with. We don’t have the hydrology, only the HEC-RAS files with the steady flows (peak flows of course). We need to make some sort of change to the channel and/or floodway to lower the 100-YR WSE in the vicinity of an existing college football field. The university has offered a piece of land slightly upstream as an area for detention. I’ve never modeled detention in HEC-RAS and I understand that’s not it’s forte but in our case, I think the best way to model this might be an unsteady model with offline storage. Perhaps I’m completely wrong with that assumption. From what I can tell I’ll need hydrographs for the unsteady model but as I’ve already mentioned, I only have peak flows. Any thoughts?

 

[cvg]

develop the hydrographs, you will need them. and since you are developing them, you can probably route them through the proposed detention basin within the same hydrology model to evaluate the effectiveness and size the basin. Depending on the design, you may still need to model the hydraulics of the diversion into the basin using HEC-RAS.

 

[MattZ99]

In order to model the detention within HEC-RAS, you will need the hydrographs. I have successfully completed several detention analyses using unsteady flow HEC-RAS models.

As cvg said, it may be easier to just do your routing within the hydrology software than to set up an unsteady flow HEC-RAS model.