"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 2013 SP1, C3D 2014
W7x64; i7 8gb; Radeon HD 5700
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