Seeking advice|URGENT

[Dessalegn Worku]

Dear all

Merry Christmas! I am writing to ask for your advice on the calibration and validation strategy in the SWAT+ toolbox.

I am modeling the impacts of climate change on the water balance components on a watershed covering about 65,000 km2. I am now doing the model calibration and validation . Besides the main outlet, I planned to calibrate and validate the model in two nested sub-catchments, covering 16,000 km2 and 1,300 km2.

In your opinion, is it better to calibrate and validate the model sequentially (e.g., smallest catchment → medium one and then → the main outlet), or to perform a simultaneous multi-site calibration that considers all three outlets together?

I would greatly appreciate and look forward to your thoughts.