The topography‐based, variable contributing area model of catchment hydrology of K. J. Beven and E. F. Wood (1983) was adapted for continuous simulation and extended to take account of observed processes in White Oak Run, a small forested catchment in Shenandoah National Park, Virginia. Automatic calibration of the model was attempted using eight different objective functions. All objective functions were indifferent to many of the model parameters and thus parameter estimation could not be done reliably. On the basis of results from a regionalized sensitivity analysis, the original model structure was greatly simplified. The parameters of the simplified model, which produced fits to the measured data very nearly as good as did the more complex model, were estimated well using a sum of squared errors criterion.