Longer simulation time step of the tracer-aided hydrological model estimates lower contribution of slow runoff components

•The simulation time step of 1 h to 24 h led to 10% difference in the estimated contribution of subsurface runoff, which decreased with the increasing time steps.•Longer simulation time step simulated lower variability of stream water isotopes because of the slower water velocity within hydrological units, and the model would estimate lower contribution of slow runoff component to offset this.•Despite the additional uncertainty from simulation time step, involving isotope into calibration objective still improved the model confidence.