Broad CrestedWeir Profile for Level Spreader
Broad CrestedWeir Profile for Level Spreader
(OP)
Hi everyone,
In HydroCAD, I'd like to model my typical level spreader as a pond with insignificant storage.
My preferred level spreader design incorporates a level "lip" that is usually 10 to 20 feet long, with a height of 1 foot.
My preferred profile is 1:1 on the upstream side, and 4:1 on the downstream side.

The closest Broad Crested profile Id is "#29," which is defined as a 1:1 on the upstream, and 3:1 on the downstream.
real question is: from what text did those Profile ID's come from, since I would like to compute my own Head coefficients to use my 1:1 flowing to 1 4:1 profile.
Thanks very much
Craig Bailey
Hudson, NH
___
Craig T. Bailey, PE
www.bailey-associates.com
In HydroCAD, I'd like to model my typical level spreader as a pond with insignificant storage.
My preferred level spreader design incorporates a level "lip" that is usually 10 to 20 feet long, with a height of 1 foot.
My preferred profile is 1:1 on the upstream side, and 4:1 on the downstream side.

The closest Broad Crested profile Id is "#29," which is defined as a 1:1 on the upstream, and 3:1 on the downstream.
real question is: from what text did those Profile ID's come from, since I would like to compute my own Head coefficients to use my 1:1 flowing to 1 4:1 profile.
Thanks very much
Craig Bailey
Hudson, NH
___
Craig T. Bailey, PE
www.bailey-associates.com





RE: Broad CrestedWeir Profile for Level Spreader
HOWEVER, with a zero-storage pond your're always going to get Qout=Qin, so the details of the weir calculations are generally of little concern. The only thing you're going to learn from the zero-storage routing is the amount of head that will develop over the weir. And a sharp-crested weir (with a constant coefficient) should be entirely adequate for that purpose.
The Broad-Crested option is only needed for pond routings that are highly sensitive to the stage-discharge relationship, and even then I've never seen a need for custom coefficients. For details please see http://www.hydrocad.net/weir1.htm
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: Broad CrestedWeir Profile for Level Spreader
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: Broad CrestedWeir Profile for Level Spreader
I understand fully. The head that may model was developing over the level lip was precisely why I asked... was not sure if the broad crested weir coefficients would make any difference.
I'll be modeling my Level Spreaders as sharp crests from now on.
Thank you very much.
Craig.
___
Craig T. Bailey, PE, LLS
www.bailey-associates.com