Hydro File Error

[Bahman Esfandiar]

Hi All,
I am getting the following error when trying to do drainage design with rational method, any suggestion?
ERROR: Hydro file Global data:Frequency must be ARI for rational method.
I am using 12d V14.0C2d and the IFD values are form BOM.

[Matthew Monk]

As I understand it, the IFD tables provided by the BoM are listed per AEP (Annual Exceedance Probability). 12d Model requires this to be expressed in ARI (Average Recurrence Interval) instead. See also this: http://www.bom.gov.au/water/designRainfalls/#sec1q5

Basically, you need to edit your IFD row of AEPs and convert them to their ARI values.

[Bahman Esfandiar]

Thanks Matt, However, I should be able to use both AEP and ARI with Rational method. I have used it before and in 12d YouTube channel there is a video (https://youtu.be/hGa4ZvvTqqQ?t=482) where the instructor clearly uses the BOM IFD data in AEP format. I am just wondering if anyone else encountered this error or am I missing something obvious.

Cheers,

[Matthew Monk]

No idea. I was just going off what the error message was saying.

[Brady Williams]

Did you download the "all design rainfalls CSV" from BOM?

In V14, only the first 10 columns in the .12dhydro IFD table can be read. If you downloaded the all design rainfalls file, chances are you will have more than 10 columns so if you are trying to run a 1% AEP or 100-year ARI, you will get an error (mine wasn't identical to yours but similar).

Try removing some of the columns you don't need and see if that works

[Owen Thornton]

Upgrade to the latest v14. It supports ARI or AEP for use with Rational. Not sure exactly which version first included this enhancement. Feels like more than two years ago.

[Bahman Esfandiar]

Updated to V.14.0C2h and problem solved.