Q/Qp templates
Q/Qp templates
(OP)
Does anyone know of a source, or how to develop a Q/Qp template for a particular region (western PA)to generate a hydrograph using the Rational Method? I've been using an example template that came with the software I use (Haestad's PondPack) but I don't know if the template is pertinent to this area. Also, how do you determine the duration, Td, of a storm when using the Modified Rational method. I understand what the time of concentration Tc,is but not how it correlates (or doesn't) to the duration of a storm.
Thanks - LPS
Thanks - LPS





RE: Q/Qp templates
A. Finding the Maximum Volume
The question now becomes "assuming a constant outflow, for what duration storm will the maximum storage volume be required?" In the sketch above, the shaded area represents that volume. The task of finding that duration and volume lends itself particularly well to a spreadsheet solution.
Click the icon to see this solution.
MAXSTOR.XLS (1 page)
Cell XX,YY contains the solution using Excel's =maximum function.
B. Limitations
The Rational Method was developed in the US in Rochester, New York and based on studies of a small number of urban drainage basins. The original studies used only small basins. For these reasons, most reviewing agencies limit its use to small drainage areas. For example, the Federal Emergency Management Agency (FEMA) accepts the Rational Method only for drainage areas of less than 100 acres. Local agencies typically adopt even lower limits; on the order of 25 acres or so.
RE: Q/Qp templates
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It is a method for generating a hydrograph using the Rational method, useful for routing storms through a detention facility. I just don't know what template is suitable for use in my area (i.e. Type II storm).
Thanks-
LPS
RE: Q/Qp templates
RE: Q/Qp templates