Physical modelling data were collected on a 61·0 cm Parshall flume to determine the sensitivity on predicted flow rate resulting from improperly located staff gauges and differing entrance conditions to the flume. Improperly located staff gauges and variant entrance conditions are a common problem in field applications. The study indicated that discharge errors of up to 60% can occur when head measurements are recorded at locations other than those specified by Parshall. Differing entrance wingwall configurations also changed the standard ratings of the flume. Due to the lack of geometric similarity between flumes of varying sizes, the creation of correction coefficients for these problems is dependent on flume size. This paper uses the data collected from the 61·0 cm physical model and the associated correction coefficients for this size flume to validate the use of numerical modelling in extending the initial study to other sized flumes. The numerical model is explained and the results of both models are compared. Acceptable agreement between the physical and the numerical models supports the use of numerical modelling in extending the correction factors to Parshall flumes of different sizes.