×
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

IDF to Incremental depth

IDF to Incremental depth

IDF to Incremental depth

(OP)
Hi,

I am going to use SCS method to size a detention pond. The problem here is, the rainfall data is in IDF curve format (A,B,C constants available). No guage data. I was told IDF curve can be transformed to depth vs. time curve, for a given distribution type, eg, Chicago.

Anybody knows how to do this? Any free software can do this?

RE: IDF to Incremental depth

You should not need to do this.

For Chicago you are probably going to be using a Type II storm.

You didn't say but you need to decide what duration storm you will use, or are required to use. Usually that is a 24 hour storm but you need to know that.

Next you need to know what Annual Exceedence Probability storm, or storms, you will use. 1%, 10% 25%, 0.5% ?
Then you need to know the total rainfall for the durations and AEPs of interest to you.  These can be found on Isospluvial maps published by NOAA. They can be downloaded at NOAA's website. Google it.

As for software you can use the NRCS ( formerly SCS ) free program WINTR-55, or HydroCad, or Hydraflow Hydrographs, or, SWMM ( free) or SMADA or HEC-HMS to generate the hydrographs for your design storm(s).

good luck

RE: IDF to Incremental depth

I think you're asking about a "Chicago-style" rainfall distribution.  This is a general technique for defining an SCS-type rainfall distribution using IDF coefficients.  This can be used anywhere, not just Chicago.

This is one of the many rainfall formats supported by HydroCAD.  For details please see www.hydrocad.net/rftables.htm

RE: IDF to Incremental depth

The IDF should actually give you a somewhat more local hyetograph than the blanket SCS Type II.  Now I wholeheartedly agree with the earlier and more useful posts (especially RWF7347 since it is unlikely that you are going to do better than the National Weather Service
), but why not select you time off the IDF compute a depth and then distribute like a type II (It is something like 40% at the peak of a 24 hour period.)  Also if you are using TR55 graphical you do even need to trouble with that.

And if you have ATLAS 14 data why even bother ruining all that databy altering it to a type II.

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