A proposed index for comparing hydrographs

Abstract

Existing goodness of fit indices are inadequate for comparing model‐generated hydrographs with measured hydrographs. The Pearson product‐moment correlation coefficient, which is the most frequently used index of regeneration, is inadequate because it is insensitive to differences in the size of the two hydrographs. A better coefficient of regeneration is obtained if Pearson's coefficient is adjusted by using a ratio of the standard deviations of the two hydrographs being compared. The resulting index is numerically the same as the regression of the hydrograph with the smaller variance on the hydrograph having the larger variance. Examples are used to illustrate the superiority of the modified correlation index.