ENV3105 Hydrology S2 2019

Running head: ENV3105 HYDROLOGY S2 2019 1
ENV3105 Hydrology S2 2019
Firstname Lastname
Name of Institution

ENV3105 HYDROLOGY S2 2019 2
Project Background
This evaluation is intended to evaluate your accomplishment of Modules 2 to 5's chosen learning
goals. The assignment includes (a) measurement and presentation of rainfall and streamflow
data, (b) analysis of flood frequency and estimation of flood design, (c) design IFD rainfall, and
(d) estimation of peak discharges. Historical streamflow and rainfall information will work with
you. The purpose of the task is to strengthen and extend your understanding of hydrological
techniques and the (significant) uncertainty connected with the assessment of design floods.
To show how hydrology can be integrated into engineering practice, a hypothetical project has
been designed. Although the project is imaginary (and unlikely to receive permission to
proceed), the different hydrological tasks included in the project are representative of what you
may encounter after graduating.
The aim of the task is to predict the design flood discharges for the stream gage site (142001A
Caboolture River at Upper Caboolture under the Pine Basin) for a range of annual excess
probabilities (2, 10 and 100-year ARIs corresponding to 50%, 10% and 1% AEPs respectively).
The assessment of flood frequency (FFA) will be based on the results of four methods: the
Annual Series, the Partial Series, the Palmen & Weeks process (Palmen and Weeks, 2014) and
the fresh Regional Flood Frequency Estimate (RFFE) instrument established as part of the
AR&R update (Rahman et al, 2015).
The task is based on the following key responsibilities:
1. Obtaining and reviewing information from streamflow
2. Annual FFA series based on fitting a distribution of the Pearson 3 log (LP3) to the maximum
annual flow
3. Partial FFA series based on a maximum of monthly release.
4. Design estimation of release using the techniques Palmen & Weeks (2014) and RFFE.
5. Compilation of estimates and choice of a set of discharges from the design flood, based on the
above inputs

ENV3105 HYDROLOGY S2 2019 3
6. Evaluation of the rainfall frequency connected with flood event in January 2011.
7. Preparing a report on the task
3.1 Streamflow data
Basic stream gauge Data
Information Required Answer
Basin name Pine Basin
Creek name Caboolture River at Upper Caboolture
Location of site Caboolture, 27o05’52.1”S (latitude) and
152o53’26.2”E (longitude)
Catchment area 94 km2 (9400 hectares)
Streamgauging commencement data 01/10/1965
Rainfall (data source A and AT) data
measurement start date
17/09/1990
Rainfall data resolution Daily
Maximum instantaneous discharge (in
cumecs) value and occurrence data (from data
source A)
604.482 cumecs, 11/01/2011
2526.620 cumecs, 15/03/2019
HYDRAULIC CONTROL AND RATING CURVE
Information Required Answer
Type of control Sand gravel

ENV3105 HYDROLOGY S2 2019 4
Image of River section and highest
recorded gauge height.
Highest gauge height = 10.50 metres
Two images, one for the most recent
rating curve and the other for a
comparison plot of gaugings and
rating curve.
Gaugings performed between
January 1966 and June 2018
275
Maximum gauged level and when
was this measured.
7.080 m on 09/01/1968
Compare this highest gauging to the
highest recorded flood (level,
discharge and measurement date).
By comparison, the highest flood recorded
occurred at 11/01/2011 with a gauge level of
10.50 m and an estimated discharge (from
the rating curve) of 604.482 m3/s (Weeks,
2009).
Comment on the adequacy of the rating Assertive for flow less than 900 cumecs: From

ENV3105 HYDROLOGY S2 2019 5
curve, especially the reliability of the
discharges associated with different
flood levels.
many gaugings, the rating curve has been
confirmed for flows (<900 m3/s (Rahman,
2008). This offers self-assurance in discharges in
this flow range only.
Low accuracy for flows more than 900 cumecs:
The largest observed flood discharge is
approximately 2526.620 m3/s. Flood discharges
are based on a theoretical rating curve and is
expected that the accuracy is low to moderate.
FLOW DURATION CURVE
Information Required Answer
Provide an image of the daily flow
duration curve of the creek.
What is the median daily flow (in cumecs)? 0.09 cumec
What is the discharge (in cumecs) that
is equalled or exceeded for 10% and
90% time in the river?
1.1 cumecs and 0.035 cumecs
What is the percent of time the flow is
very low or close zero?
4%
4. ANNUAL SERIES FLOOD FREQUENCY ANALYSIS

ENV3105 HYDROLOGY S2 2019 6
1. Provide a Table (in word or copy from excel) showing water year ending from 1966 to 2018,
peak discharge and number of missing data. Highlight the water years that have at least one
month of missing discharge data.
Water year
ending
Peak discharge
(m3/s)
Missing data
months
1966 35.17 1
1967 292.22 0
1968 184.31 0
1969 77.24 2
1970 331.22 0
1971 298.11 1
1972 533.71 0
1973 161.38 0
1974 493.34 0
1975 94.07 0
1976 205.82 0
1977 22.83 3
1978 132.06 1
1979 336.79 0
1980 87.57 0
1981 129.83 0
1982 243.57 5
1983 194.14 3
1984 131.32 0
1985 66.42 0
1986 39.76 2
1987 56.56 9
1988 403.68 5
1989 371.93 0
1990 169.54 0
1991 560.33 4
1992 323.93 2
1993 22.79 12
1994 65.23 2
1995 151.95 3
1996 407.85 2
1997 41.68 5
1998 86.36 6
1999 273.85 0
2000 49.84 3
2001 173.57 4