×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

HEC-RAS 5.0.7 cannot calculate infiltration for each cells?

HEC-RAS 5.0.7 cannot calculate infiltration for each cells?

HEC-RAS 5.0.7 cannot calculate infiltration for each cells?

(OP)
Just started to use HEC-RAS 2D to calculate the flow depth and velocities. I am using HEC-RAS 5.0.7. I noticed it cannot calculate the infiltration for each cells. I have to calculate infiltration by myself when Computing Excess Rainfall Hyetograph using a averaged CN for the whole site. And then use the Excess Rainfall Hyetograph as a boundary condition.

Here are the equations I use:
Fa=S*(P-Ia)/(P-Ia+S)
where, P, Fa, S and Ia have the same unit of length [L]. Usually total rainfall (P) is known, and S is computed by using the CN (assumed to be given for this exercise) as shown in the equation below:
S= (1000/CN)-10)
Where S is in inches. the continuous abstraction term Fa gives the amount of rainfall that is lost as infiltration from the total rainfall.

I do realize this is not accurate to use an averaged CN. Am I not using the software properly? What is the correct way? Any guidance will be greatly appreciated! T.I.A.

RE: HEC-RAS 5.0.7 cannot calculate infiltration for each cells?

HEC-RAS 5.0.7 does not account for infiltration or initial abstraction. The precipitation data on SA/2D boundary condition has be be the excess rainfall hyetograph. Unless you want to be conservative and assume no infiltration and all the rainfall runoff are conveyed to your 2D flow area. It is more of hydraulics computation and less hydrology. Your other alternative will be switch to HEC-HMS which does little of both.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close