Using the same data set used for problem 6 of assignment 1, fit a Log-Pearson type 3 probability distribution
and calculate the discharges which equates to the 2 year, 5 year, 10 year, 25 year, 100 year and 200 year
As part of your work, you must show:
ï‚· all of your calculations and workings;
ï‚· a graph which compares the actual measured data and the fitted probability distribution function; and
ï‚· a description of the actual data versus fitted PDF including comments on its goodness of fit and any
other aspects you may think relevant.
Make sure all units are correctly shown and that your graph axes are appropriately scaled and titled.
Problem 2 (7 marks)
Create an MS Excel spreadsheet which shows the computational steps to solve the following problem:
ï‚· Consider a 2-acre stormwater detention basin with vertical walls.
ï‚· Assume a triangular inflow hydrograph which increases linearly from zero to a peak of 60 cfs at 60 min
and then decreases linearly to a zero discharge at 180 min.
ï‚· Route the inflow hydrograph through the detention basin using the head-discharge relationship for the
5-ft diameter pipe spillway shown in Table 9.2.1 (see below) noting that the pipe is located at the
bottom of the basin.
ï‚· Assuming the basin is initially empty, use the level pool routing procedure with a 10-min time interval
to determine the maximum depth in the detention basin.
Note that this problem has been taken from Chapter 9 of the text Mays (2001) Water Resources Engineering.
John Wiley & Sons. You may like to refer to this text to assist you with this problem.
The results for this problem are shown in Table 9.2.2 below. Your task is to create an MS Excel spreadsheet
which re-creates these results. In addition, create a graph which compares in the inflow and outflow
hydrographs and provide some comments on the magnitude of peak attenuation and also peak lag time.
Ensure you spreadsheet is properly labelled so that others can read, interpret and understand your results.