High Early Discharge (HED) Strucutures
High Early Discharge (HED) Strucutures
(OP)
How do you define HED? Can you help to give me examples and sketches/drawings. Any refernce to read up this topics? What are the advantages using HED and when should we use them?
Your advice shall be very much appreciated
Your advice shall be very much appreciated





RE: High Early Discharge (HED) Strucutures
http://ww
One benefit of "high early discharge" would be to make optimum use of detention storage by passing the early flow, thus leaving more of the storage available to handle the peak flow, later in the storm. Vortex values and similar devices are sometimes used for this purpose.
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: High Early Discharge (HED) Strucutures
RE: High Early Discharge (HED) Strucutures
Sometimes it feels like we can't win from an environmental standpoint.
RE: High Early Discharge (HED) Strucutures
RE: High Early Discharge (HED) Strucutures
While we do not use the term HED here, its use would apply to water Quantity control rather Quality control (someone pointed out that water quality would suffer...but it could be achieved elsewhere in the overall stormwater management).
Here, we have regulations for quantity contol. An HED type strategy would apply only if one showed that normal quantity control would aggrevate downstream flooding. This would usuallly happen near the bottom of a watershed, where detaining the site discharge peak can make the peak overlap the peak coming from the upper watershed. In this situation it can be advantageous to push the site peak out early so that the peaks aren't additive.
Like Peter, I did a google search of the term and noticed it is used in manuals in AU. The manuals seemed be concerned with outlet control structures (primary discharge orifices in particular) being submerged by tailwater.
RE: High Early Discharge (HED) Strucutures
yes, that is true. However with ephemeral desert streams (what we call dry washes or arroyos), if you divert them into a detention basin you may dry up the stream completely and that causes the vegetation to die. The permitting agencies generally consider this to be more of an environmental impact than to allow the dirty water to flow in the stream. So generally, low flows are required to be maintained in the stream.
RE: High Early Discharge (HED) Strucutures