The performance of a quasi-physically based rainfall-runoff model is evaluated for a set of 72 events from a small upland catchment based upon two levels of characterization for overland flow plane geometry. In the first level of characterization there are 22 overland flow planes with average estimates of steady state infiltration rates based upon soil type. In the second level of characterization there are 145 overland flow planes centered upon the locations of steady state infiltration rate measurement sites. Model performance is also evaluated for four different estimates of antecedent soil water content for a subset of 39 events for the more detailed overland flow plane characterization. The results show only slight improvements in model performance for the more detailed characterization of overland flow plane geometry and soil hydraulic property information.