Smaller dt Hint Message

[amicka]

We're trying to replicate the work done in an older version of HydroCAD using version 9.00. We are getting message 49 "Hint: Tc<2dt may require smaller dt" for one of our subcatchments. The Tc is 5.8 minutes.

Our dt was set at 0.50, which we reduced to 0.10, but the message remains.

What do we need to change to satisfy the program and get rid of this message? Or is this something that should not concern us?

 

[hydroponder]

Usually, if the dt is 1/2 of the smallest Tc or less, the error should not come up. There is a possibility that your minimum Tc is set greater than 5.8 minutes. You can change this in Settings -> Calculation -> Advanced, but this is usually a different error message.

 

[psmart]

The default dt of 0.05 hours is suitable whenever the Tc is 0.1 hours (6 minutes) or greater. For a smaller Tc you will get hint 49, suggesting a smaller dt. (Be sure to click the message for full details!)

For your Tc of 5.8 minutes, reducing the dt to 0.04 hours will eliminate the message.

Note: The "Minimum Tc" setting is used to arbitrarily raise any Tc that falls below the specified threshold. This feature is intended for use ONLY when a minimum Tc is prescribed by local regulations. Otherwise the actual Tc value should be used.

For further information please see

http://www.hydrocad.net/tc.htm

Peter Smart
HydroCAD Software

http://www.hydrocad.net