×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• 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.

# Rainfall Intensity Equation Coefficient outside of Denver

## Rainfall Intensity Equation Coefficient outside of Denver

(OP)
I'm trying to develop an IDF curve for Craig, Colorado. I'm using the UDFCD Rational Method spreadsheet and have the appropriate 1-hour rainfall depths but I can't seem find the appropriate coefficients for the Rainfall Intensity Equation (a, b, and c). Is there an adjustment factor or a table somewhere based on zone?

### RE: Rainfall Intensity Equation Coefficient outside of Denver

(OP)
thanks beej67. I used these depths to develop an IDF curve that I can use. I was hoping to be able to come up with an equation for use in our spreadsheets. I did some more research and realized that the coefficients from the equation were derived from the curve using Excel Solver, which I don't have the time to learn how to use so I'll just use the curve for now.

### RE: Rainfall Intensity Equation Coefficient outside of Denver

one mouse click and the equation is solved
create a x,y (scatter) chart
display the equation on the chart

ok, 3 mouse clicks

### RE: Rainfall Intensity Equation Coefficient outside of Denver

Yr, a0, a1
1, 0.103903, 0.313687
2, 0.128763, 0.305261
5, 0.177688, 0.291029
10, 0.226557, 0.279501
25, 0.307198, 0.264093
50, 0.379736, 0.253163
100, 0.462293, 0.242978
200, 0.555014, 0.233734
500, 0.694905, 0.222314
1000, 0.807472, 0.215545

DDF Coefficients calculated using PDF from NOAA for Craig, CO (ID 05-1928)
Inch = a0 x (minutes ^ a1)
Where a0 and a1 are the coefficients for year yr

See http://www.hydrocalc.com/beta/rain_ddf/main.html#
You can also convert the DDF to either IDF or to Hyetograph.
Thanks

#### 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.

#### 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
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!