49256 – FLOOD ESTIMATION
ASSIGNMENT 1
The Powells Creek catchment which is located in the Inner Western Suburbs of Sydney drains stormwater runoff from an urban area into Homebush Bay. A stream gauge has been operating on this stormwater channel since 1958. The catchment area upstream of the gauging station is 2.4km2.
The annual maxima series of flows is
|
Year |
Flow (m3/s) |
Year |
Flow (m3/s) |
Year |
Flow (m3/s) |
|
1958 |
15.98 |
1972 |
37.97 |
1986 |
20.20 |
|
1959 |
48.16 |
1973 |
33.45 |
1987 |
11.81 |
|
1960 |
10.75 |
1974 |
28.91 |
1988 |
23.10 |
|
1961 |
7.01 |
1975 |
16.96 |
1989 |
13.94 |
|
1962 |
19.99 |
1976 |
14.94 |
1990 |
23.30 |
|
1963 |
32.97 |
1977 |
16.46 |
1991 |
19.19 |
|
1964 |
25.30 |
1978 |
15.07 |
1992 |
17.05 |
|
1965 |
8.79 |
1979 |
12.61 |
1993 |
6.85 |
|
1966 |
12.56 |
1980 |
12.74 |
1994 |
13.32 |
|
1967 |
17.20 |
1981 |
14.61 |
1995 |
7.81 |
|
1968 |
5.33 |
1982 |
19.31 |
1996 |
7.63 |
|
1969 |
18.26 |
1983 |
21.26 |
1997 |
7.11 |
|
1970 |
17.44 |
1984 |
21.33 |
|
|
|
1971 |
12.14 |
1985 |
13.07 |
|
|
Part 1
a) Using these data, undertake a flood frequency analysis to estimate the flood flows associated with events having AEPs of 1%, 2%, 5% and 10%.
b) Determine the confidence limits for these flows.
c) Comment on the likely accuracy of these estimates.
Part 2
Assume the full period of record were not available and only 11 years of record is available..
a) Determine the expected design quantiles for the following periods
a) 1960 to 1970
b) 1970 to 1980
c) 1980 to 1990
b) Discuss differences in the estimates. Include in your discussion of the differences, how the flood events included in each of the samples differ and the significance of these differences.
Assignment Presentation
The report is to be written as a memo from an employee to a manager outlining the basis of the study, the methods of analysis used, and will develop some conclusions and a recommendation. Hence the report will include an introduction, a main body, and some conclusions.