A simple transformation of the incomplete gamma function was used to describe single-peaked hydrographs. A weighted least-squares method produces a forced fit of the crest portion of the observed hydrograph. In addition to determining the parameters of the fit with minimum squared deviations, the computer plots the original and fitted hydrographs and calculates statistics to assist in making an objective decision as to the hydrological goodness-of-fit. A good least-squares fit does not necessarily result in a good hydrologic fit. Judgment of goodness-of-fit on the central portion of the hydrograph is aided by a significance test which combines the number of data points with features of the ocular fit (balancing of volumes and minimizing of deviations). The complete goodness-of-fit test assumes that: (1) the assumed model is correct; and (2) if the model is a correct one, there is a close mathematical relation between the observed and fitted data. (WRSIC Abstract).