For your numerical models, what is your calibration workflow?
There are multiple ways I guess, if the study site doesn’t have any streamflow gauge I don’t see how can calibration be done accurately because you will be comparing against other models and comparing with them with no ground truth. I guess that’s the engineering judgement.
If it does have a streamflow gauge, let’s say your first run gave you a volume ratio of about 0.4. So your model runoff at that gauge is about half of what was observed. What parameters do you change first to do calibration? I imagine decrease infiltration? Change infiltration methods? Maybe slightly alter manning’s n if timing of the peak is off.
But until when? Like within 10% margin of your calibration target? Does it rest on your engineering judgement? Does your firm or workplace or government policy have any threshold assigned?
But models like hecras doesn’t account for subsurface flow so if your study site has preferential flow pattern in the vadose zone that is not accounted for by the model then I suppose that’s might be a limitation too.