Does automatic calibration in GSSHA match hydrograph shape?

[Sushban]

GSSHA needs observed peak and volume flow data to compare calibration runs for a closeness of fit. If an observed hydrograph has multiple peaks for a single event, how will automatic calibration in GSSHA deal with that? Also, does automatic calibration in GSSHA tends to match observed peak and volume only, but not the shape of hydrograph?

[Chris Smemoe]

There's not a way to calibrate to multiple peaks for a single event using GSSHA's built-in calibration. I think the calibration will match the observed peak and volume and not necessarily the shape of the hydrograph.

[Sushban]

That's what I thought. I have a question, in general, for Chris and others interested. What parameters are most sensitive to controlling the shape (slope, volume,..) of falling limb of hydrograph?

[Chris Smemoe]

I'd say rainfall, Green-Ampt infiltration parameters (especially hydraulic conductivity), and overland roughness would impact the shape of the hydrograph. The shape of your watershed will also have some impact on the shape of your hydrograph. Stream roughness values may also impact the shape. Those are basically all the main parameters in a GSSHA model. Try playing with these parameters and see how the hydrograph shape changes.

[Sushban]

I learned about WMS supporting PEST based auto-calibration method from this link:

http://www.xmswiki.com/xms/WMS:GSSHA_Calibration

I was trying to explore more about it but I can't find "Calibration Setup" button in WMS to set up PEST auto-calibration. I am using WMS 9.1.12 version. Does WMS support both SCE and PEST auto-calibration method?

[Chris Smemoe]

Sushban,

WMS 10.0 beta supports PEST-based auto-calibration at the outlet point. This method works much better than the previous SCE-based calibration. The link you mention above is valid for WMS 10.0 beta, which is available for download from the aquaveo.com web site and should run if you have a current license. A tutorial describing how to setup an auto-calibration model using WMS 10.0 is available on the xmswiki.com WMS tutorial page. There's a link to the tutorial from the xmswiki page you mention above. WMS 10.0 and GSSHA still support both PEST-based and SCE auto-calibration but the SCE calibration options are deprecated and will not be supported in a future version.

Thanks,

Chris

[Sushban]

Thanks Chris,

I guess I will have to burn the keys to switch to WMS 10 (Beta) Version, is that correct?

Is there an expected date for the release of WMS 10 regular version?

[Chris Smemoe]

Sushban,

If your maintenance is not expired on your WMS 9.1 version, you should be able to download and run WMS 10.0 beta. The final WMS 10.0 version will be released sometime during November.

Thanks,

Chris