Broad Crested Weir Interference

[KatiLynSki]

I have an existing dam outlet that in plan is two broadcrested weirs that are 90 degrees to one another. The longer broadcrested weir (~14') is located perpindicular to the flow and the shorter broadcrested weir (~10') is located parallel to the flow.

I know the design flows over the spillway. I am trying to calculate the water height during a 100-year storm.

Is there a procedure that should be used to account for the interference due to the layout? Should I just use the sum of the two weirs as the weir length? A fraction of the sum?

Any insight or documentation of a similar case would be appreciated.

 

[gbam]

If I understand the configuration, one is perpendicular to flow and one parallel to flow, correct?. For that configuration I would consult Chow, Open Channel Hydraulics for side weir flow leaving while using the perpendicular weir as control. Hopefully, I understand the layout.

 

[cvg]

you will need to adjust your side flow weir to account for momentum losses. The flow has to turn 90 deg and flow towards the weir crest.