Wednesday, September 26, 2018

Participate in the Development of HEC-RAS-Spatial Precipitation and Infiltration

Here's an opportunity to have a direct impact on the development of spatial precipitation and infiltration methods in HEC-RAS.  Please read the message from Gary Brunner, Lead Developer of HEC-RAS, and if you would like to provide feedback to his questions, please do so in the comments section at the bottom of this post.  If you would rather email me your response, you can send them to

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I will close the poll on October 3rd, so please have your responses in by then.  

This poll is now closed.  Thanks to all who participated.  

From Gary:
"I need some help from all of you.  We are working on adding spatial precipitation and infiltration methods into HEC-RAS for our version 5.1 release.  I need to ask the HEC-RAS users some questions in order to make better decisions as to which infiltration methods should be put into HEC-RAS.  Right now we are planning on adding three methods into HEC-RAS:

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  • Initial and Constant, with an option for re-instating the initial loss after a dry period
  • SCS Curve Number.  However modified to allow for the following:  User entered initial loss; separating Impervious from pervious surfaces, so curve number will only be applied to pervious surfaces; and re-instating initial loss after a dry period.
  • Green and Ampt.  During periods of no or low rainfall, the soil moisture is redistributed and the infiltration capacity is recovered."

Please answer the following questions and post in the comments section below or email to

1.  Do you think it is a good idea to put infiltration methods into HEC-RAS?

2.  If so, what methods would you like to see?

3.  Have you used the SCS Curve number method in any hydrologic modeling investigations?

4.  If you have used the SCS method, was it successful in calibrating the model?  Or did you need to switch to a different method?