Predicting the Runoff from Storm Rainfall, Volume 30

The estimation of the volume of runoff to be expected from a given volume of rainfall is a fundamental problem in flood forecasting. Such estimates are necessary before the unit hydrograph or other techniques can be used to predict the streamflow hydrograph. The authors describe the technique now used at the River Forecast Centers of the U.S. Weather Bureau for evaluating the effect of season, antecedent conditions, duration of rainfall and rainfall amount in determining the portion of the rainfall contributing to storm runoff. Special problems encountered in flood forecasting are emphasized. The technique, developed and tested over several years, yields a high degree of accuracy in estimated runoff. Although prepared by empirical procedures, the close agreement between relations for basins of similar hydrologic characteristics suggests that rational parameter have been adopted. The similarity between relations also simplifies the work required for their preparation.