Question 1 1. The ammual floods in Black Jack Creek are log -normally distributed with a mean off 800 ML /d and a standard deviation of 2.0 ML /d. [In full : the logarithms of the largest floods in each your are normally distributed and the mean of the logarithms of the annual floods is 800 ML /d and the standard deviation of the logarithms of the annual floods of 2.0 ML /d]- ) What is the probability of having a flood , in any one year , which is equal to or Larger them 800 ML /d b) What is the probability of having a flood , in any one year , which is equal to or Larger them 4000 ML /8 c) What is the magnitude of the 1 in 100 your discharge in this Crock What is the magnitude of the 5-your , 10 -your , 20 -year , and 50 -year events in this crack - Question 2 Background Black Range Creek drains a rural catch- ment - A road is being designed that will cross the Black Range Crook and you are asked to estimate design floods . The following data have been provided by your supervisor There is one gauge on Black Range Crack where the catchment area is 54.4 kim , and : summany of the gauging record from 1969 to 1961 is shown in the following table Estimate flows for Average Recurrence Intervals of 2, 5, 10, 20, 30 and 100 years An unbiased estimate of the population ABP for am event of rank m, is given by: AEP = (m-0.4 )(N +0.2 ) AEP = Annual exceedance probability ; m = Rank ; N = Number of years of record a) Calculate a. the mean of the annual flood discharges b. the standard deviation of the flood discharges C. the mean of the logarithms of the flood discharges (give your answer in natural and log units d. the standard deviation of the logarithms of the flood discharges b) Assume the discharges are log normally distributed and calculate the 1 in 20-year flood Question 3: Annual maximum floods in White Dog Crock are log -normally distributed . The average and standard deviation of log Q are 3 and 0.5 respectively . Flows have boon measured in units of ML /d. What is the magnitude of the 100 -year ARI flood