A 60-year annual series of peak discharges in SI units fits a log-normal distribution. The mean of the log discharges is 3.0 and the standard deviation of the log discharges is 0.21.
(I) What is the return period for a discharge of 2000 m3/s?
(2) What is the return period for a discharge of 3000 m3/s?
(3) Determine the probability that the discharge of 3000 m3/s will occur in the next 100 years.
(4) Find the discharge that has a return period of 50 years.