Calibration of a Catchment

[sfRLeFe]

Harc –

I have modelled a small multi catchment drainage network using RORB 6.45.
One of the catchments (2.24 Km2) in size has been previously modelled by numerous others detailing the critical storm 1% flow using DRAINS, RAFTS-XP as well as TUFLOW with broadly similar results (around 25 – 30m3/sec).
I am trying to calibrate my RORB model with the expectation that I can use the established calibration values throughout the remaining drainage network of my model.

Unfortunately, the 1% AEP-20 minute storm flow that I am getting for this catchment within my RORB model is generating a peak flow of around 700m3/sec – significantly different. I have checked areas and adjusted the kc values accordingly. I have left the m value at 0.8

Can anyone advise what could possibly be incorrect in my model to create such a discrepency?
Thanks in advance – Paul

[Benson Liu]

Hi Paul,

One thing to check would be the volume you are getting in RORB, if the volume in RORB is also much higher then what you are expecting then this points to an issue with the rainfall. Normally such a large increase in flow (and volume) is caused by an incorrect time-step being used when inputting the rainfall.

Kind regards,

Benson

[danny.burkett]

On a somewhat related topic, I am seeking advice on how to input an actual rainfall event (6 minute intervals) so that I can calibrate the model against various rainfall and stream gauging stations.

[Benson Liu]

Hi Danny,

You can do this by setting up a storm file. Setting up a storm file and running it through RORB allows you to input rainfall and recorded streamflow data and compare it to the modelled output. Details on how to set up a storm file are in the RORB manual Table 5.2, item 7 onwards.

Kind regards,

Benson

[Author]

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