Monte Carlo simulation summary results

Tagged: extreme events, Monte Carlo, rare

This topic has 5 replies, 3 voices, and was last updated 1 year, 4 months ago by Matt Scorah.

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April 12, 2018 at 2:27 PM #972

JM
Participant

Hi

I am running a Monte Carlo simulation and in the output text file under ‘Summary of Runs for Critical Duration Analysis’ I am only getting results for AEP events 2 to 50.
Is there a way to get the summary to show results for 1 in 100 events as well?
I am using RORB V6.32 and ARR2016.

Thanks

April 12, 2018 at 2:47 PM #973

Matt Scorah
Moderator

Hi,

In order to generate results for a given AEP of interest you require runs that have been generated using rainfalls either side of that AEP – therefore, to estimate 1 in 100 floods you need rainfalls rarer than 1 in 100. For this reason RORB will not report Monte Carlo results for the first and last AEPs specified in your IFD input.

When downloading IFDs from the BoM website design rainfalls are split into three different tables – Very Frequent, IFD (up to an AEP of 1 in 100) and Rare (AEP of 1 in 100 to 1 in 2000). You will need to download both the IFD and Rare tables and combine them (either in the RORB interface or Excel) and rerun the model to get results for an AEP of 1 in 100.

I hope this helps!

April 12, 2018 at 2:50 PM #974

JM
Participant

Thank-you for the quick reply.

July 4, 2023 at 5:28 PM #3031

_nikkatorres
Participant

Hi, I’m running Monte Carlo for extreme events and sometimes there are unreliable values. What does “ie bound by interval contributions to AEP > 20% total” mean?

ex: I ran 200yr, 500yr, 1000yr, 2000yr, 5000yr, 10 000yr, and 20 000yr. Only 2000yr was reliable

Peak flows for selected AEPs (* indicates value unreliable, ie bounded by interval contributions to AEP > 20% total)

No. AEP(1inY) Peak 01
1 500 475.43*
2 1000 484.84*
3 2000 551.69
4 5000 701.04*
5 10000 841.63*

Any general advice as to how I can always ensure that my values are reliable?

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July 5, 2023 at 11:54 AM #3033
Matt Scorah
Moderator
Hi,

I’ll give a brief overview of what this message means, but you can find more info in the manual about some of these concepts. If you don’t want the explanation and just want the answer, it is “extend the depth frequency curve”.

EDIT: I hit the character limit, will follow up with another post
- This reply was modified 1 year, 4 months ago by Matt Scorah.
July 5, 2023 at 12:02 PM #3035

Matt Scorah
Moderator

I’m having issues with the forum right now, if you send an email to enquiries@dev7.preflight.com.au I’ll explain the theory behind that message
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Monte Carlo simulation summary results

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