A spillway is being designed for a dam on the Feather River at Oroville, California (Prob. 1.7). The problem is to make the most reliable forecasts of future maximum annual floods. Compare the fit of the data to the normal, lognormal, and Type I extreme-value model. Use probability paper.
(a) Compare forecasts of 10-, 50- and 100-year floods.
(b) What model appears to give the best fit?
(c) For each model, what is the most likely (i.e., the modal value of the) maximum annual flood to be found in any one year? What is the probability of finding a flood equal to or greater than double this magnitude? Are these magnitudes particularly sensitive to the choice of model?