Associative relationships between moments of rainstorms and the corresponding hydrographs.

Abstract

The effects of rainfall intensity distribution on runoff hydrographs were studied for 89 watersheds, using event data obtained from the USDA-ARS. Treating the hyetograph and hydrograph as frequency distributions, their shapes were described by the first four statistical moments. A number of other measures of the rainfall and runoff were calculated (rainfall depth and duration, maximum 15-minute intensity, watershed moisture status; runoff depth and duration, peak runoff rate, peak rate relative to event rainfall and runoff depths, runoff ratio, and runoff Curve Number). The rainfall moments and measures were compared to those of the hydrographs, and statistical associations were drawn. The first two moments of the hyetograph and hydrograph were significantly correlated, while the shape parameters of skew and peakedness were less so. The dispersion of the rainfall intensity distribution is a significant factor affecting the correlations between the commonly studied parameters mentioned above.