Modeling Diversion in HEC-HMS 1

[Rookie2]

Hi, I'm trying to model a water quality / detention pond in HEC-HMS that has two outflow structures draining in different directions. One outlet (riser) drains to a second pond, the other (concrete spillway) discharges to a channel. I was hoping for some advice on how to split the flow in the model. I have been reading about the diversion element in HEC-HMS, but I'm not sure this will do what I need it to. There is a lateral weir diversion (primarily for offline ponds) and I was thinking of trying to use this but not sure how. Anyone with experience doing this? Any help would be appreciated. Thanks

 

[froude]

Rookie2,

It sounds like you may be able to utilize the "Auxiliary Discharge Location" feature (see HEC-HMS User's Manual - Chapter 9 Reservoir Elements). Using this, you will be able to model both the riser and the weir with flow from the riser going into your downstream pond element and flow from the weir going into your channel/routing elements.

1. In the main reservoirs tab (where you specify the number of outlets, spillways, elev-area function, etc.) you need to specify the node to which you want to send auxiliary flow. There should be a dropdown menu next to the "Auxiliary:" option.

2. In the outlets tab (where you specify the shape and characteristics of your outlets), set the riser to drain in the "Main" direction and set your weir to drain in the "Auxiliary" direction.

Hope this works for you. Good luck.

 

[Rookie2]

Thanks Froude! That's exactly what I needed.