Hydraflow Storm Sewers - Rational Equation

[jrennickUQAYD]

I'm looking for some insight on how Storm Sewers handles the frequency factor (Kr in SS) in the Rational Equation.  Per the user manual, Kr = 1:

However, some drainage manuals specify that the frequency factor varies based on the storm event:

For a long time, my workflow has been to create multiple SS files for the different storm events that I want to analyze, with the C-value of each drainage area adjusted based on the required frequency factor.  However, this gets tedious, especially for large networks.

My question is this:  Does Storm Sewers adjust the frequency factor for different storm events?

[matt_anderson_pe]

Kr is not Ki.   Kr is a unit conversion factor.  Its not exposed, so you cant change it.

Ki is a multiplier for rainfall.  It probably would be just as easy simply increase your rainfall values by 10, 20 or 25%.

[lim.wendy]

Hi Jacob,

Thank you for submitting your question in our discussion forums. 

I see you are visiting as a new member of the Civil 3D forum. Welcome to the Autodesk Community!

Thanks for reaching out to the forum. Have you had a chance to look over Matt's suggestions?

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[fcernst]

No just can’t hit the Q like that... because you have to make sure C x Cf <= 1

[matt_anderson_pe]

i.e., it works ok if C < 0.8.   It's a manual validation.