SSA 2018 - IDF curve entered correctly but seems to not work as expected

[Tentie]

I have entered in all our data to generate the IDF curve for 2 to 100 years.  I have run the analysis using the 5 year and 100 year options and see no difference in any of the generated numbers like Max HGL, MAX EGL, etc.

I am working in metric units.

Am I misunderstanding something or doing something wrong?  The larger year should give larger answers.

Any advise is appreciated.

Glen

[mzjensen]

Glen,

Can you give a little more info on your project setup? What components do you have in your system? Are you using the Rational Method? Are the calculated "Rainfall intensity" values in the subbasin properties the same when you try each return period?

[Tentie]

Sorry - I should have come back and updated things.

It appears that the system I was working on was SEVERLY undersized and therefore the affect the IDF curve had was not measurable.  When I ran the 2 year and 100 year storms, there appeared to be no difference.  After playing for a while, I upsized some pipes and then I could see the differences.  The existing pipe network is well less than 50% of the size required for the flows that are being seen in the area (lots of flooding).  Now that I have confirmed this, it makes sense with what flows we are actually seeing in the area.

Thank you for your reply.

Glen

[mzjensen]

I see. Glad you got it figured out.