How to “freeze” calibrated parameters in the SWAT+ToolBox:

[Afonso Augusto Magalhães de Araujo]

Hello everyone!

Once you calibrate the parameters of an upstream basin and freeze them, can the NSE result change?

I set up the complete project in the SWAT+ ToolBox, inserting all the fluviometric stations (daily scale), as well as the respective parameter blocks for the respective units of HRUs and AQUs for each channel. (see attached figures).

I started the calibration by channel 108, having obtained an NSE = 0.491, I understand that this result can impact the downstream results, as shown in the attached figure.

From there, I fixed the set of calibrated parameters for channel 108, using the interface button (see figure attached) and proceeded to the calibration of channel 122. Curiously and, in my view, inexplicably and inconsistently, the result of channel 108, even with the parameters frozen and having no relation to channel 122, has its result changed in calibration time ( see figure attache  ).

Therefore, I would like to understand, why, having calibrated channel 108 and fixed its parameters, in the course of the calibration of channel 122, the results for channel 108 are modified?

Please, could someone help me with this?

[celray....@gmail.com]

Hi,

When you want to calibrate by subbasin going downstream, make sure each parameter set you add is attached to specific HRUs (and aquifers) in that region. if you add parameters without specifying their region, they will apply to all objects and will affect all objects the moment they are changed. if that is the case, fixing parameters will not work as intended.

also keep in mind that some parameters will always affect all objects in your model (e.g surlag)

PS: Please post to SPT group