How to calculate the percentage of measurement error?

[jamil]

Dear SWAT-CUP users,

I am new to SWAT-CUP and would like to know what is exactly the "Percentage of measurement error" that has to be specified in the "Observed.txt" file of the Objective function section?

I guess it has something to do with the standard deviation of the measured data that is used to compute the R-factor?

Does anyone know how to calculate this parameter?

Thanks in advance,

Jamil

[Karim]

That is the average expected error in your observed data. It is used to calculate the r-factor and the p-factor..

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[jamil]

Thanks for the answer, but how can I calculate this parameter from my observed data? Can I consider it as the accuracy of the measurement device of the observed data? (for instance the limnimetric scale to calculate my observed daily flow values?)

Thanks again,

Jamil

[Karim]

You cannot calculate it. It is the accuracy of the measurement. For discharge about 10-20% is reasonable. For sediment it should be much more!

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[jamil]

Ok, I'll leave it to the default value then, thanks for the advice!

Jamil

Le mardi 16 avril 2013 17:30:28 UTC+2, jamil a écrit :

[Jessica Chen]

Dear Dr Abbaspour,

Can you elaborate on that? How are p and r-factor calculated based on error in observation data? Thanks!

Best,

Jessica

[Abbaspour, Karim]

If (observation +/- percent error * observation) is in the 95ppu, then it is treated as being bracketed by the 95ppu.

Karim

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