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lOtion technique similar to the method of steepest descent for optimizing an unconstrained problem will be devised to evaluate the storm parameters appearing in the resulting hyetograph equations. The "stan- dard" rainfall intensity-duration data for a number of major cities in the United States will be calculated from Weather Bureau Technical Paper No. 40 (1961) and supplemented by NOAA Atlas 2 (Miller, Fred- erick, and Tracey, 1973). These "standard" data will be further utilized to evaluate the "standard" storm- pattern parameters, the values of which are expected to vary slightly with localities, but not with fre- quency. For completely describing a storm pattern based on the rainfall intensity-duration-frequency relationship, the skewness of the temporal pattern must be specified or evaluated by other means. There seems to be no way to estimate the skewness except by analyzing the most intense rainfalls of various durations recorded at the location under consider- ation. Major storms for a number of stations will be selected from ARS experimental watersheds (ARS mack Book Series, 1933-67) and analyzed, in addi- tion to the major storms collected in the Salt Lake City area (Fletcher and Chen, 1975). However, the analysis may fail to produce the average storm skewness, if meaningful at all, for each station under study. Finally, a graphical method will be proposed to evaluate the Ustandard" storm-pattern parameters, which with the help of Weather Bureau Technical Paper No. 40, will be used to derive a storm pattern for any station with a desired frequency. For understanding the characteristics of the generalized design stonn-pattern equations, the equa- tions will be normalized so that dimensionless para- meters which play a significant role in the formula- tion of the design hyetograph will be identified, Sensitivity and interaction of the parameters in the generalized design storm pattern will be studied, 2