A probability plot of 19 yr of peak discharges for the West Branch of the Mahoning River near Newton Falls, Ohio, is shown in Fig. P3-20 this is an example of Gumbel, or extreme-value I, probability paper. Simply use the straight, fitted line to obtain the answers.
(a) What is the 25-yr flow?
(b) What is the 100-yr flow?
(c) What is the return period of a flow of 4000 cfs?
(d) What is the probability that the annual peak discharge will fall between 5000 and 7000 cfs?