CIV E 445 - APPLIED HYDROLOGY
SPRING 2014
HOMEWORK No. 8

  1. Use the Weibull formula (Eq. 6-26) to calculate the plotting positions for the following series of annual maxima, in cubic feet per second:
    8020, 3260, 2210, 1735, 5550, 3560, 3745, 3040, 3500, 2010, 1835, 7350, 4350, 2890, 2620, 1405, 1165, 5505, 6080, 6215, 7015, 6925.

  2. Fit a log Pearson III curve to the data of Problem 1. Plot the calculated distribution on log probability paper, along with the Weibull plotting positions calculated in 1. Verify your hand calculations with ONLINE PEARSON.

  3. Given the following statistics of annual maxima for river Y: number of years n = 35; mean = 1550 m3/s; standard deviation= 435 m3/s; mean of the logarithms = 3.05; standard deviation of the logarithms = 0.3; skew coefficient of the logarithms = -0.2. Compute the 100-y flood using the following probability distributions: (a) normal, (b) Gumbel, and (c) log Pearson III.