Multiple structures in outlet structure of a detention pond

[BillsSis]

Hello,
I use HEC-HMS to route water through a detention pond. To find the elevation - discharge curve, I use Excel to find the discharge relating to its relevant elevation - using the Weir or Orifice Equations as appropriate. I'm working on a detention pond that has a 4' wide by 45' long concrete flume, with a trapezoidal weir in the middle of its length. The drawing of the weir and the flume is attached to this message. How would I analyze this situation? Do I analyze the water first as its coming into the 4' wide flume? Then, use the weir formula as the water flows through the weir? If so, what numbers do I put in the weir formula?

I appreciate any and all advice.

 

[Twinkie]

You need to route toewall>trapezoidal weir

 

[BillsSis]

Hi Twinkie,
By the greater-than sign, do you mean for me to route the water through the toewall first, then through the weir?

Thanks!

 

[Twinkie]

Yes

 

[BillsSis]

Thank you Twinkie. I appreciate your time and knowledge.