Variability in flow and tracer-based performance metric sensitivities reveal regional differences in dominant hydrological processes across the Athabasca River basin

•Sensitivity analyses identify regional variations in parameter sensitivity.•Flow metrics alone cannot fully calibrate a process-based hydrologic model.•Flow metric sensitivities limited to processes affecting flow volume and timing.•Isotope metrics respond to processes impacting mixing, basin storage and water age.•The relative importance of hydrological processes can be highly variable.