December 1, 1971
There is no universally acceptable technique available to estimate the magnitude and frequency of floods. The “rational method”, empirical formulae and regional analysis all have restrictions. The remaining approaches are deterministic, using design precipitation maxima and probabilistic, the latter using streamflow data to calculate frequencies. The concepts of design maxima and the fitting of statistical distributions to flood frequencies are discussed in detail. It is concluded that a more logical cost/benefit approach is required to decision making in spillway design.