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.


Rainfall Intensity Equation Coefficient outside of Denver

Rainfall Intensity Equation Coefficient outside of Denver

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

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
add a trend line
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

Please verify before use.

You can also convert the DDF to either IDF or to Hyetograph.

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!


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