AutoCAD Civil 3D - Stormwater

Valued Mentor
Posts: 1,089
Registered: ‎01-07-2011
Message 11 of 12 (202 Views)

Re: Hydraflow - Modified Rational Method - Storm Duration

12-05-2012 12:30 PM in reply to: *Matt.Anderson

"Hydraflow Hydrographs will stop figuring the Intensity out when it hits 
60 minutes which is the highest value in the IDF curve it can calculate."


This is incorrect. It uses the FHA IDF curve equation to extrapolate out past the 60 minute intensity value.

Fred Ernst, PE
C3D 2015
Ernst Engineering
Posts: 2,909
Registered: ‎05-13-2005
Message 12 of 12 (185 Views)

Re: Hydraflow - Modified Rational Method - Storm Duration

12-12-2012 12:34 PM in reply to: fcernst

Fred -


The SDF stopping at 9.9 is an issue development has been notified. 


A bit of clarification on the statement regarding IDF calculations stopping at 60 minutes back when I noted it in 2009.  The defects have been fixed.

Matthew Anderson, PE
Product Manager

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