Hydrology Report
NWC Low Flow Project – Case Study in
Derivation of Residuals and Flow Generation
in the Paroo and Burdekin Catchments using
various conceptual models and climatic data
October 2011
Disclaimer
This document has been prepared with all due diligence and care, based on the best available information at the time of
publication. The department holds no responsibility for any errors or omissions within this document. Any decisions made by
other parties based on this document are solely the responsibility of those parties. Information contained in this document is
from a number of sources and, as such, does not necessarily represent government or departmental policy.
i
Contents
List of tables
iii
List of figures
iv
1
Overview
1
2
Trial Catchments
2
2.1
Paroo River
2
2.2
Broken River
5
3
4
Available Data
6
3.1
Rainfall Data Sets
6
3.2
Evaporation Data
6
3.3
Paroo River
7
3.4
Broken River
7
Results
9
4.1
9
Paroo River
4.1.1
4.1.2
4.2
Using Alternative Conceptual Models to Derive Inflows for River System
Simulation Models
Using Alternative Rainfall Data Sets in Rainfall Runoff Modelling
9
15
Broken River
19
4.2.1
19
Using Alternative Rainfall Data Sets in Rainfall Runoff Modelling
5
Preliminary Findings and Discussion
24
6
References
26
ii
List of tables
Table 3.1 Paroo River Gauges
7
Table 3.2 Rainfall Stations
7
Table 3.3 Broken River Gauges
7
Table 3.4 Rainfall Stations
8
Table 4.1 Low flow indicators selected for the Paroo and Broken Rivers
13
Table 4.2 Low flow indicators statistics for the Paroo River from Caiwarro to Willara Crossing
14
Table 4.3 Low flow indicators statistics for the Paroo River from Caiwarro to Willara Crossing
Runoff Generation
18
Table 4.4 Low flow indicators statistics for the Broken River at Crediton
23
iii
List of figures
Figure 2.1 Paroo Catchment Locality Map
3
Figure 2.2 Locality Map for the Reach from Caiwarro to Willara Crossing
4
Figure 2.3 Broken River Locality Map
5
Figure 4.1 Ranked Plot of the flow at Willara Crossing and the various calculated residuals
9
Figure 4.2 Plot of continuous flow at Willara Crossing and the various calculated residuals
10
Figure 4.3 Ranked Plot of the flow at Willara Crossing and the various calculated residuals
11
Figure 4.4 Plot of continuous flow at Willara Crossing and the various calculated residuals
12
Figure 4.5 Plot of Residual Flow compared to the generated runoffs from 05/03/1983 to
19/12/1984
15
Figure 4.6 Plot of Residual Flow compared to the generated runoffs from 05/10/1986 to
21/07/1988
16
Figure 4.7 Plot of Residual Flow compared to the generated runoffs from 29/03/1999 to
12/01/2001
16
Figure 4.8 Log Ranked Plot Plot of Residual Flow compared to the generated runoffs
17
Figure 4.9 Continuous Flow of Gauge Flows compared to generated runoffs from 23/06/1956
to 04/10/1958
19
Figure 4.10 Continuous Flow of Gauge Flows compared to generated runoffs from
04/10/1958 to 15/01/1960
20
Figure 4.11 Continuous Flow of Gauge Flows compared to generated runoffs from
27/04/1961 to 08/08/1962
20
Figure 4.12 Continuous Flow of Gauge Flows compared to generated runoffs from
16/04/1970 to 28/07/1971
21
Figure 4.13 Continuous Flow of Gauge Flows compared to generated runoffs from
27/10/1981 to 07/02/1983
21
Figure 4.14 Log Ranked Plot of the of Gauge Flows compared to generated runoffs less than
100 ML/day
22
Figure 4.15 Log Ranked Plot of the of Gauge Flows compared to generated runoffs less than
40 ML/day
22
iv
Hydrology Report: NWC Low Flow Project
1
Overview
The aim of this study is to evaluate if the simulation of low flows in river models can be improved by the
use of:
1. alternative conceptual models in deriving inflows for river system simulation models.
2. alternative rainfall data sources in rainfall runoff modeling.
.
To test the use of different conceptual models in deriving inflows for river system simulation models, five
different conceptual models were applied to simulate instream processes for a reach of the Paroo River
using an IQQM model of the reach. These were:
1. calculated residual inflows
2. residuals calculated using storage estimates
3. residuals calculated using storage estimates and calibrated losses
4. residuals calculated using storage estimates and stream evapotranspiration
5. residuals calculated using storage estimates, stream evapotranspiration and calibrated losses
To test the use of alternative rainfall data sets in rainfall runoff modeling, Sacramento models calibrated
during earlier Water Resource Planning studies had the following climatic data sets applied to them.:
1. Grid rainfall from the Enhanced Meteorological Data (SILO)
2. Infilled Rainfall gauges from the Enhanced Meteorological Data (SILO)
3. Infilled Rainfall gauges using the available BOM Rainfall Gauge Network
The Paroo rainfall runoff modelling testing was initially undertaken using the first two climatic data sets.
It was found that the climatic data were causing inconsistent catchment responses when results were
compared to the recorded flow data. So to assess the impact of using alternative rainfall data sets the three
data sets were applied for a catchment in the Broken River, in the Burdekin Catchment. The catchment
was chosen because, from a rainfall runoff perspective, it is simpler and smaller than the Paroo
Catchment.
To evaluate any improvement of low flow estimates by applying different conceptual models and climatic
data, duration curves and time series plot of modelled and observed flows were visually compared with
particular consideration of the timing, duration, frequency and magnitude of low flow events and zero
flow days. Results were also compared using performance indicator metrics. For the Paroo Reach, the
performance indicator metrics were selected because they were found to be those most consistently
relevant for describing the hydrologic characteristics of a Class 12 river (Kennard et al, 2009). Rivers
under this category are characteristic of arid and semi-arid regions and are described as ‘variable summer
extremely intermittent’ (>250 zero-flow days per year). For the Broken River, performance indicator
metrics were selected because they were found to be those most consistently relevant for describing the
hydrologic characteristics of a Class 7 river (Kennard et al, 2009). Rivers under this category are
distributed in the eastern side of Australia and are described as ‘unpredictable intermittent’. The selected
low flow metrics were statistically assessed using the River Analysis Package v3.0.3 (Marsh, Stewardson
and Kennard, 2003).
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Hydrology Report: NWC Low Flow Project
2
Trial Catchments
Two catchments were selected for this study : the Paroo and the Burdekin. Within each of these
catchments, one river section was chosen: The catchment between the Caiwarro to Willaro Crossing
gauges in the Paroo River and the Broken River at Crediton. A brief description of the catchments and the
selected river sections is presented below.
2.1
Paroo River
The headwaters of the catchment (Figure 2.1) are situated in the Warrego and Wallaroo Ranges. The river
flows southwest through Queensland and into N.S.W. where it discharges into a complex flood plain
south of Wanaaring, as it approaches the Darling River between Tilpa and Wilcannia.
The Paroo River is a dryland river, which most of the time consists of a series of disconnected waterholes.
The recorded mean annual flow in the river at Caiwarro, which is the last gauged point on the Paroo in
Queensland, is 546893 ML/yr (1968-2002). While the average flow is large, there is a considerable
variability of flow within the recorded periods, including long periods with no flow. At Caiwarro, there is
no flow for an estimated 60% of the time.
The catchment is very flat with its highest point being less than 200 m above sea level.
The mean annual flow discharging into the Darling River is estimated at 140861 ML/yr (1889-2002, from
full calibration model). The severe reduction in mean annual flow along the Paroo River is attributed
mostly to tributary breakouts, the numerous ephemeral lakes and the floodplain losses in the south of the
catchment.
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Hydrology Report: NWC Low Flow Project
Figure 2.1 Paroo Catchment Locality Map
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Hydrology Report: NWC Low Flow Project
Caiwarro (QLD AMTD 57.3 km) to Willara Crossing (NSW AMTD 290.4 km) is located in the central
part of the Paroo River System. The reach extends mainly northwest of the Paroo River, and is bound to
the west by the Bulloo River System, and the Warrego River System to the east. The mainstream length
of the Paroo River from Caiwarro to Willara Crossing is about 96 km.
The reach has a total area of 10212 km2 but there is a large number of natural waterholes and lakes taking
water that would otherwise flows into the Paroo River, including Lake Numulla, Lake Wyarra,
Bindegolly, Hutchinson, and Tomaroo. Lakes Hutchinson, Binedegolly and Toomaroo, are fed by
Bundilia Creek. These lakes have a large catchment area within the Paroo catchment, but are often dry.
Because of this the effective catchment area is 1565 km2.
Two main tributaries join the Paroo River between Caiwarro and Willara Crossing, Caiwarro Creek and
Barton’s Creek, but they do not flow for most of the time. The majority of the area of the reach will turn
into floodplains during floods and channel the water to the Paroo River.
The average annual rainfall varies from about 200 mm/a in the central and western areas to a maximum of
around 300 mm/a in the northwest.
Figure 2.2 Locality Map for the Reach from Caiwarro to Willara Crossing
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Hydrology Report: NWC Low Flow Project
2.2
Broken River
The catchment of G.S.120204, Broken River at Crediton (A.M.T.D. 98.3 km), is located in the southeastern part of the Burdekin River Basin. A map of the catchment area is illustrated in Figure 2.3.
The Broken River rises in the Clarke Range, which forms the eastern boundary of the catchment, and
flows westward towards Eungella Dam.
The catchment area to the Crediton gauge is approximately 41 km2. The biggest town in the area is
Crediton, which is located roughly at the centre of the catchment.
The average annual rainfall is relatively uniform across the catchment, decreasing from 1800mm to
1600mm moving east to west.
Figure 2.3 Broken River Locality Map
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Hydrology Report: NWC Low Flow Project
3
Available Data
3.1
Rainfall Data Sets
Daily rainfall data was available for the whole of the Paroo River and Broken River over the desired
period 1889–2009. It was obtained through the use of both Patched Point Dataset (PPD) and Data Drill
through the SILO NRM Enhanced Meteorological Datasets. Three types of climatic dataset were
employed to conduct the analysis in this study:
1. Grid rainfall from the Enhanced Meteorological Data (SILO)
2. Infilled Rainfall gauges from the Enhanced Meteorological Data (SILO)
3. Infilled Rainfall gauges using the available BOM Rainfall Gauge Network
Gridded data (Data Drill) and Patched Point Dataset (PPD) provide continuous daily climate data, suitable
for use in simulation models. However there are subtle but important differences between the two sets.
The PPD uses original Bureau of Meteorology measurements for a particular meteorological station, but
with interpolated data used to fill ("patch") any gaps in the observation record. The Data Drill accesses
grids of data attained through the use of a procedure developed by DNR&M (Carter, et al, 1996) to
interpolate point rainfall data at 0.05 degree latitude/longitude grid intervals using recorded daily rainfall
data from the Bureau of Meteorology. The procedure uses a type of spline technique for interpolation,
making use of elevation as well as horizontal position, and taking into account long-term variability of the
rainfall at each rainfall station being used. The data in the Data Drill are all synthetic; there are no original
meteorological station data left in the calculated grid fields. However, the Data Drill does have the
advantage of being available for any set of coordinates in Australia.
The PPD would typically be used when an analysis or simulation is needed quite close to a
meteorological station. However, if an analysis is required for a location which has no meteorological
station nearby, then the Data Drill is the more relevant product.
The third rainfall data set that has been utilised are the long term BOM rainfall stations, which are infilled
with surrounding rainfall stations normalised to account for any variation in long term rainfall.
3.2
Evaporation Data
A consistent potential evapotranspiration has been used in all of the rainfall runoff models to exclude any
potential interference in the effect of different rainfall (Table 3.2).
Table 3.2 Pan evaporation Station Details
Reach
3
Name (Sub Areas
Included)
Caiwarro to Willara
(p10 to p14)
Area
(km2)
10212
Effective
Area (km2)
1565
Average Annual Rainfall
(mm/a)*
272
6
Average Annual
Evapotranspiration (mm/a)
2403(p12),2410(p13)
Hydrology Report: NWC Low Flow Project
3.3
Paroo River
Stream flow data from the Willara Crossing station (424002 NSW AMTD 290.4 km), which is situated
30 km south of the QLD/NSW border, were obtained from the DLWC, N.S.W through the NSW
Provisional River Data website.
Caiwarro station is a current operational stream gauge, which has been collecting data since 1967. Willara
Crossing station is also a current operational stream gauge, which has been collecting data since 1975.
Table 3.1 Paroo River Gauges
Station
424201a
Paroo River at Caiwarro
57.3 (Qld)
17/04/1967 –current
Station No
Name
AMTD
Period Record
Station
424002
Paroo River at Willara Crossing
290.4 (NSW)
22/11/975 - current
Three long-term rainfall stations within the catchment area were examined and listed in Table 3.2.
Table 3.2 Rainfall Stations
3.4
NUMBER
NAME
RECORD PERIOD
44032
Eulo Post Office
1889-current
44181
Hungerford
1889-current
48079
Wanaaring Post Office
1889-current
Broken River
The catchment discharges have been measured at G.S.120204A and G.S.120204B, Broken River at
Crediton, A.M.T.D. 98.3 km.
Details of these gauging stations are presented in Table 3.3. The location of these gauges can be seen on
Figure 2.3.
Table 3.3 Broken River Gauges
Station No
Name
AMTD
Period Record
Station
120204a
Broken River at Crediton
98.3
1/10/1955 –31/8/1981
Station
120204b
Broken River at Crediton Recorder
98.3
1/10/1963– 1/10/1988
Several long-term rainfall stations within or adjacent to the catchment area were examined. For the point
rainfall based data sets one rainfall station, Dalrymple Heights, was used to represent the catchment in the
rainfall runoff model. Additional rainfall stations were used to infill the Dalrymple Heights missing
periods in the BOM recorded data based set of data. These are listed in Table 3.4.
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Hydrology Report: NWC Low Flow Project
Table 3.4 Rainfall Stations
NUMBER
NAME
RECORD PERIOD
33016
Dalrymple Heights
1938-current
33055
Netherdale Post Office
1912-1975
33026
Finch Hatton Cook Street
1914-2004
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Hydrology Report: NWC Low Flow Project
4
Results
4.1
4.1.1
Paroo River
Using Alternative Conceptual Models to Derive Inflows for River System
Simulation Models
The use of five alternative conceptual models was tested in the Paroo River catchment between Caiwarro
and Willara Crossing.
The period used for comparison for this river was 01/01/1990 to 02/01/2007. This period was chosen as
there were no missing daily data values for the observed site. RAP requires data sets without missing
values and the period chosen best suited the observed data set with minimal infilling.
In the figure 4.1 is presented the ranked plot of the observed flow and three of the five conceptual models:
 Observed flow at Willara gauge, represented by the red line
 Residual calculated using inflows, represented by the blue line
 Residual calculated using storage estimates, represented by the green line
 Residuals calculated using storage estimates and calibrated losses, represented by the pink line
Paroo section f rom Caiw arro to W illara
10
10
ML /d
10
10
10
10
01/01/1990 to 02/01/2007
W illara
inflow s
storage
storage and los
20
80
5
4
3
2
1
0
0
10
30
40
50
60
70
% T ime Exceeded or Equaled
Figure 4.1 Ranked Plot of the flow at Willara Crossing and the various calculated residuals
9
90
100
date:29/09/11 tim e:15:00:00.70
Hydrology Report: NWC Low Flow Project
In figure 4.2 are displayed the events between 16-10-1999 and 28-6-2000 for the observed flow and three
of the five conceptual models:
 Observed flow at the Willara gauge, represented by the red line
 Residual calculated using inflows, represented by the blue line
 Residual calculated using storage estimates, represented by the green line
 Residuals calculated using storage estimates and calibrated losses, represented by the pink line
Paroo section f rom Caiw arro to W illara
W illara
inf low
storage
storage and los
26/10/1999 to 25/06/2000
200000
180000
160000
140000
120000
ML /d
100000
80000
60000
40000
20000
N ov
D ec
Jan
Feb
Mar
Months
A pr
Figure 4.2 Plot of continuous flow at Willara Crossing and the various calculated residuals
10
May
Jun
date:29/09/11 tim e:15:06:38.05
Hydrology Report: NWC Low Flow Project
In figure 4.3 is presented the ranked plot of the observed flow and two of the five conceptual models:
 Observed flow at Willara gauge, represented by the red line
 Residuals calculated using storage estimates and stream evapotranspiration, represented by the
blue line
 Residuals calculated using storage estimates, stream evapotranspiration and calibrated losses,
represented by the green line
Paroo secti on f rom Cai w arro to W i l l ara g
01/01/1990 to 02/01/2007
10
10
ML /d
10
10
10
10
W il l ara gauge
storage-ev ap
storage-ev ap-lo
5
4
3
2
1
0
0
10
20
30
70
60
50
40
% T i m e Ex ceeded or Equal ed
Figure 4.3 Ranked Plot of the flow at Willara Crossing and the various calculated residuals
11
80
90
100
date:29/09/11 ti m e:14:55:39.79
Hydrology Report: NWC Low Flow Project
In figure 4.4 are displayed the events between 16-10-1999 and 28-6-2000 for the observed flow and three
of the five conceptual models:
 Observed flow at the Willara gauge, represented by the red line
 Residuals calculated using storage estimates and stream evapotranspiration, represented by the
blue line
 Residuals calculated using storage estimates, stream evapotranspiration and calibrated losses,
represented by the green line
W illara
491 W illara Gauge
491 W illara Gauge
16/10/1999 to 28/06/2000
Flow
Simulated flow
Simulated flow
50000
45000
40000
35000
30000
ML /d
25000
20000
15000
10000
5000
0
N ov
D ec
Jan
Feb
Mar
Months
A pr
Figure 4.4 Plot of continuous flow at Willara Crossing and the various calculated residuals
12
May
Jun
date:29/09/11 tim e:12:35:30.67
Hydrology Report: NWC Low Flow Project
The ecologically relevant low flow performance indicator metrics (Marsh 2011) are listed in Table 4.1.
These metrics were selected to describe the following key flow characteristics:
 Magnitude of (low) flow events

Frequency of (low) flow events

Duration of (low) flow events

Timing of (low) flow events
Table 4.1 Low flow indicators selected for the Paroo and Broken Rivers
Metric
Magnitude of low flows
Median of annual minimum flows
Low flow discharge 75th percentile
Low flow discharge 90th percentile
Frequency of low flows
Total Number of low spell > 3-day
Total Number of low spell > 7-day
Total Number of low spell > 30-day
Low flow spell number (<75th percentile)
Total of periods between low spells (<75th percentile)
Unit
Acronym
No unit
Mlday-1
Mlday-1
MedAnnMin
P75
P90
Days
Days
Days
year-1
Days
LSNum_3day
LSNum_7day
LSNum_30day
LSNum_P75
LSTotDurPerBetw_
P75
HSTotDurPerBetw
_P75
LSNum_P90
LSTotDurPerBetw_
P90
HSTotDurPerBetw
_P90
Days
Total of periods between high spells (<75th percentile)
Low flow spell number (<90th percentile)
year-1
Days
Total of periods between low spells (<90th percentile)
Days
Total of periods between high spells (<90th percentile)
Duration of low flows
Total Duration of low spell > 3-day
Days
Days
Median Annual Duration of low spell > 3-day
Days
Days
Days
LSTotDur_3day
MedAnnLSTotDur3day
LSTotDur_7day
MedAnnLSTotDur7day
LSTotDur_30day
MedAnnLSTotDur30day
LSTotDur_P75
LSTotDur_P90
NumZeroDay
No unit
JDMinMed
Days
Days
Total Duration of low spell > 7-day
Median Annual Duration of low spell > 7-day
Days
Days
Total Duration of low spell > 30-day
Median Annual Duration of low spell > 30-day
Total duration of low spell (<75th percentile)
Total duration of low spell (<90th percentile)
Number of zero-flow days
Timing of low flows
Median Julian date of annual minimum
The low flow metrics for the various scenarios and the recorded flow at Willara gauge were calculated for
comparison with the River Analysis Package v3.0.3 (Marsh, Stewardson and Kennard, 2003). The RAP
outputs are displayed in Table 4.2.
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Hydrology Report: NWC Low Flow Project
Table 4.2 Low flow indicators statistics for the Paroo River from Caiwarro to Willara Crossing
Observed
Flow
Modelled Flow
Case 1:
calculated
residual inflows
Abbreviation
Willara
gauge
Start based on User
Start
01/01/1990
01/01/1990
End Date
End
02/01/2007
02/01/2007
Name
Case 2: residuals
calculated using storage
estimates
Case 3: residuals calculated using
storage estimates and calibrated
losses
Case 4: residuals calculated using
storage estimates and stream
evapotranspiration
Case 5: residuals calculated using
storage estimates, stream
evapotranspiration and calibrated losses
01/01/1990
01/01/1990
01/01/1990
01/01/1990
02/01/2007
02/01/2007
02/01/2007
02/01/2007
Magnitude of low flows
153
Percentile 75
P 75
155
261
Percentile 90
P 90
1566
2002
170
186.5
170
1689
2108
1663
Median of annual minimum flows
MedAnnMin
0
0
0
0
0
Total Number of low spell > 3-day
LSNum_3day
52
97
Total Number of low spell > 7-day
LSNum_7day
42
46
43
90
54
86
42
43
Total Number of low spell > 30-day
LSNum_30day
24
14
56
24
24
25
LSNum_P75
102
20
86
109
101
126
101
LSTotDurPerBetw_P75
1552
1551
1550
1549
1553
1548
HSTotDurPerBetw_P75
4588
4590
4588
4589
4591
4589
LSNum_P90
61
61
66
62
101
61
LSTotDurPerBetw_P90
621
621
621
621
621
621
HSTotDurPerBetw_P90
5369
5371
5358
5369
5369
5369
2493
1606
2289
2464
2282
131
88
141
131
131
124.5
2454
1398
2516
2454
2420
2152
130.5
82.5
130.5
130.5
128
117.5
Total Duration of low spell > 30-day
Median Annual Duration of low spell > 30day
Total duration of low spell (<75th percentile)
LSTotDur_3day
MedAnnLSTotDur3day
LSTotDur_7day
MedAnnLSTotDur7day
LSTotDur_30day
MedAnnLSTotDur30day
LSTotDur_P75
2123
989
2159
2123
2095
1636
113.5
84.5
113.5
113.5
110
125.5
4659
4660
4661
4662
4658
4663
Total duration of low spell (<90th percentile)
LSTotDur_P90
5590
5590
5590
5590
5590
5590
NumZeroDay
2532
1753
2642
2532
2507
2394
15
15
15
Low flow spell number (<75th percentile)
Total of periods between low spells (<75th
percentile)
Total of periods between high spells (<75th
percentile)
Low flow spell number (<90th percentile)
Total of periods between low spells (<90th
percentile)
Total of periods between high spells (<90th
percentile)
Total Duration of low spell > 3-day
Median Annual Duration of low spell > 3-day
Total Duration of low spell > 7-day
Median Annual Duration of low spell > 7-day
Number of zero-flow days
Median Julian date of annual minimum
JDMinMed
13
13
1695
0
Frequency of low flows
52
Duration of low flows
2493
Timing of low flows
13
14
Hydrology Report: NWC Low Flow Project
4.1.2
Using Alternative Rainfall Data Sets in Rainfall Runoff Modelling
Grid Data and PPD infilled with rainfall data were used to generate runoff estimates from a calibrated
Sacramento model for the catchment in the Paroo River.
The Sacramento model for the reach had been previously calibrated during the development of the Paroo
WRP IQQM model using grid rainfall.
The grid rainfall and patchpoint rainfall data sets have the same long term average but have a significant
difference in the flows generated.
The following plots and tables present the results of the various rainfall data sets for the Paroo River.
Comparision of Generated Runof f s against
Calculated Residual Flow s
10
10
10
10
10
ML /d
10
10
10
10
10
5
Calc Residual F
SI L O Grid
SI L O Patch
05/03/1983 to 19/12/1984
4
3
2
1
0
-1
-2
-3
-4
1983
1984
Y ears
date:30/09/11 tim e:14:56:04.29
Figure 4.5 Plot of Residual Flow compared to the generated runoffs from 05/03/1983 to 19/12/1984
15
Hydrology Report: NWC Low Flow Project
Comparision of Generated Runof f s against
Calculated Residual Flow s
10
10
10
10
10
ML /d
10
10
10
10
10
Calc Residual F
SI L O Grid
SI L O Patch
05/10/1986 to 21/07/1988
5
4
3
2
1
0
-1
-2
-3
-4
1987
1988
Y ears
date:30/09/11 tim e:14:58:00.18
Figure 4.6 Plot of Residual Flow compared to the generated runoffs from 05/10/1986 to 21/07/1988
Comparision of Generated Runoff s against
Calculated Residual Flow s
10
10
10
10
10
ML /d
10
10
10
10
10
Calc Residual F
SI L O Grid
SI L O Patch
29/03/1999 to 12/01/2001
5
4
3
2
1
0
-1
-2
-3
-4
1999
2000
Y ears
date:30/09/11 tim e:15:01:26.39
Figure 4.7 Plot of Residual Flow compared to the generated runoffs from 29/03/1999 to 12/01/2001
16
Hydrology Report: NWC Low Flow Project
Ranked Plot of the Residual Flow
Caiw arro to W illara Crossing
10
10
10
10
ML /d
10
10
10
10
10
10
01/01/1976 to 31/12/2009
Calc Resid Flow
SI L O Grid
SI L O Patch
20
80
5
4
3
2
1
0
-1
-2
-3
-4
0
10
30
40
50
60
70
% T ime Exceeded or Equaled
90
100
date:30/09/11 tim e:15:04:30.01
Figure 4.8 Log Ranked Plot Plot of Residual Flow compared to the generated runoffs
The low flow metrics for the various scenarios were calculated with the River Analysis Package v3.0.3
(Marsh, Stewardson and Kennard, 2003) and they are presented in table 4.3.
17
Hydrology Report: NWC Low Flow Project
Table 4.3 Low flow indicators statistics for the Paroo River from Caiwarro to Willara Crossing Runoff Generation
Name
Abbreviation
Observed
Flow
120204A
gauge
Modelled Flow
Sacramento
Reporting Period Summary
Start based on User
Start
01-01-1976
01-01-1976
End Date
End
31-12-2009
31-12-2009
Minimum flow Percentile 75
P 75
1
0
Minimum flow Percentile 90
P 90
116
85
MedAnnMin
0
0
Total Number of low spell > 3-day
LSNum_3day
373
77
Total Number of low spell > 7-day
LSNum_7day
255
72
LSNum_30day
89
59
Magnitude of low flows
Median of annual minimum flows
Frequency of low flows
Total Number of low spell > 30day
low flow spell number (<75th
percentile)
Total of periods between low spells
(<75th percentile)
low flow spell number (<90th
percentile)
Total of periods between low spells
(<90th percentile)
LSNum_P75
331
86
LSTotDurPerBetw_P75
2779
2146
LSNum_P90
202
78
LSTotDurPerBetw_P90
1233
1224
Total Duration of low spell > 3-day
LSTotDur_3day
8702
10166
MedAnnLSTotDur-3day
270.5
304
LSTotDur_7day
8195
10141
MedAnnLSTotDur-7day
252
298.5
LSTotDur_30day
5728
9922
MedAnnLSTotDur-30day
144
296.5
LSTotDur_P75
9634
10178
LSTotDur_P90
11180
11180
NumZeroDay
9002
10178
1
1
Duration of low flows
Median Annual Duration of low
spell > 3-day
Total Duration of low spell > 7-day
Median Annual Duration of low
spell > 7-day
Total Duration of low spell > 30day
Median Annual Duration of high
spell > 30-day
Total duration of low spell (<75th
percentile)
Total duration of low spell (<90th
percentile)
Number of zero-flow days
Timing of low flows
Median Julian date of annual
minimum
JDMinMed
18
Hydrology Report: NWC Low Flow Project
4.2
Broken River
4.2.1
Using Alternative Rainfall Data Sets in Rainfall Runoff Modelling
The use of the following alternative rainfall datasets was tested on a previously calibrated Sacramento
model of the Broken River upstream of Crediton:
 Grid rainfall from the Enhanced Meteorological Data (SILO)
 Infilled Rainfall gauges from the Enhanced Meteorological Data (SILO)
 Infilled Rainfall gauges using the available BOM Rainfall Gauge Network
The period used for comparison for this river was 01/01/1956 to 31/12/1987. This period was chosen as
there were no missing daily data values for the observed site. RAP requires data sets without missing
values and the period chosen best suited the observed data set with minimal infilling.
The rainfall runoff model was originally calibrated to the SILO Grid data so the simulation of the runoff
with the SILO Grid should simulate the flows better than the comparative runoffs generated from the
other rainfall datasets.
The follow figures present recorded and simulated flows for different time periods at Crediton.
The rainfall station based data sets pick up individual events better in most cases and hence model the
recessions better than the grid data. This is key in representing the low flows in this catchment.
B roken River at Crediton
Flow
Gauge Flow
SI L O Grid
SI L O Patch
I nf ill Rain
23/06/1957 to 04/10/1958
10
10
ML /d, , ,
10
10
10
4
3
2
1
0
1957
1958
Y ears
date:27/09/11 tim e:11:26:47.54
Figure 4.9 Continuous Flow of Gauge Flows compared to generated runoffs from 23/06/1956 to 04/10/1958
19
Hydrology Report: NWC Low Flow Project
B roken River at Crediton
Flow
Gauge Flow
SI L O Grid
SI L O Patch
I nf ill Rain
04/10/1958 to 15/01/1960
10
10
ML /d, , ,
10
10
10
4
3
2
1
0
1959
Y ears
date:27/09/11 tim e:11:27:16.55
Figure 4.10 Continuous Flow of Gauge Flows compared to generated runoffs from 04/10/1958 to 15/01/1960
B roken River at Crediton
Flow
Gauge Flow
SI L O Grid
SI L O Patch
I nf ill Rain
27/04/1961 to 08/08/1962
10
10
ML /d, , ,
10
10
10
4
3
2
1
0
1961
1962
Y ears
date:27/09/11 tim e:11:27:40.25
Figure 4.11 Continuous Flow of Gauge Flows compared to generated runoffs from 27/04/1961 to 08/08/1962
20
Hydrology Report: NWC Low Flow Project
B roken River at Crediton
Flow
Gauge Flow
SI L O Grid
SI L O Patch
I nf ill Rain
16/04/1970 to 28/07/1971
10
10
ML /d, , ,
10
10
10
4
3
2
1
0
1970
1971
Y ears
date:27/09/11 tim e:11:28:33.03
Figure 4.12 Continuous Flow of Gauge Flows compared to generated runoffs from 16/04/1970 to 28/07/1971
B roken River at Crediton
Flow
Gauge Flow
SI L O Grid
SI L O Patch
I nf ill Rain
27/10/1981 to 07/02/1983
10
10
ML /d, , ,
10
10
10
4
3
2
1
0
1982
Y ears
date:27/09/11 tim e:11:30:44.25
Figure 4.13 Continuous Flow of Gauge Flows compared to generated runoffs from 27/10/1981 to 07/02/1983
21
Hydrology Report: NWC Low Flow Project
B roken River at Crediton
Ranked Plot
Gauge Flow
SI L O Grid
SI L O Patch
I nf ill Rain
01/01/1955 to 31/12/1992
10
1
ML /d
10
2
10
0
20
30
40
50
60
70
% T ime Exceeded or Equaled
80
90
100
date:27/09/11 tim e:11:34:17.66
Figure 4.14 Log Ranked Plot of the of Gauge Flows compared to generated runoffs less than 100 ML/day
B roken River at Crediton
Ranked Plot
Gauge Flow
SI L O Grid
SI L O Patch
I nf ill Rain
01/01/1955 to 31/12/1992
1
ML /d
10
10
0
45
50
55
60
65
70
75
80
% T ime Exceeded or Equaled
85
90
95
100
date:27/09/11 tim e:11:34:36.22
Figure 4.15 Log Ranked Plot of the of Gauge Flows compared to generated runoffs less than 40 ML/day
22
Hydrology Report: NWC Low Flow Project
The low flow metrics for the various scenarios were calculated with the River Analysis Package v3.0.3
(Marsh, Stewardson and Kennard, 2003) and they are presented in table 4.4.
Table 4.4 Low flow indicators statistics for the Broken River at Crediton
Name
Abbreviation
Observed
Flow
120204A
gauge
Modelled Flow
Credsac – Grid
Pat204 – Patchpoint
Drf204_2 – Infill rainfall
Reporting Period Summary
Start based on User
Start
01-01-1956
01-01-1955
01-01-1955
01-01-1955
End Date
End
31-12-1987
31-12-1990
31-12-1990
31-12-1990
Minimum flow Percentile 75
P 75
62
595
59
59
Minimum flow Percentile 90
P 90
144
152
160
159
MedAnnMin
1
4.5
4.5
4
Magnitude of low flows
Median of annual minimum flows
Frequency of low flows
Total Number of high spell > 3-day
HSNum_3day
1
1
1
1
Total Number of high spell > 7-day
HSNum_7day
1
1
1
1
HSNum_30day
1
1
1
1
HSNum_P75
210
133
134
135
LSTotDurPerBetw_P75
2913
2901
2900
2888
HSTotDurPerBetw_P75
8679
8689
8681
8695
LSNum_P90
210
74
91
88
LSTotDurPerBetw_P90
1166
1168
1166
1164
HSTotDurPerBetw_P90
10444
9901
9898
9899
Total Number of high spell > 30day
High flow spell number (<75th
percentile)
Total of periods between low spells
(<75th percentile)
Total of periods between high
spells (<75th percentile)
High flow spell number (<90th
percentile)
Total of periods between low spells
(<90th percentile)
Total of periods between high
spells (<90th percentile)
Duration of low flows
Total Duration of high spell > 3day
Median Annual Duration of high
spell > 3-day
Total Duration of high spell > 7day
Median Annual Duration of high
spell > 7-day
Total Duration of high spell > 30day
Median Annual Duration of high
spell > 30-day
Total duration of high spell (<75th
percentile)
Total duration of high spell (<90th
percentile)
Number of zero-flow days
HSTotDur_3day
11688
11688
11688
11688
MedAnnHSTotDur-3day
365
365
365
365
LSTotDur_7day
11688
11688
11688
11688
MedAnnHSTotDur-7day
365
365
365
365
LSTotDur_30day
11688
11688
11688
11688
MedAnnLSTotDur-30day
365
365
365
365
LSTotDur_P75
2950
2948
2948
2934
LSTotDur_P90
1181
1172
1173
1172
NumZeroDay
113
0
0
0
328
352
348
Timing of low flows
Median Julian date of annual
minimum
JDMinMed
355
23
Hydrology Report: NWC Low Flow Project
5
Preliminary Findings and Discussion
Testing the ability of five alternative conceptual models to derive inflow sequences for river system
simulation models in the Paroo River has identified that the more defined are the stream processes that
contribute or impact on the low flows, the better is the ability of the model to simulate the low flows.
No clear conclusion can be drawn from the testing of the use of alternative rainfall datasets to generate
runoff estimates with rainfall runoff models.
In the Paroo River, the modelled runoff estimates are cluttered and vary significantly from event to event.
There are several processes that could be impacting on our ability to interpret the data, including:
 Size of catchment
 Floodplain Interaction
 Soil Moisture Stores
 Connectivity of catchment areas
On the basis of these inconclusive results for the Paroo River, the Broken River was then utilised to test
the impact of using alternative rainfall datasets on the generation of the runoff. The rainfall station based
data picks up individual events better in most cases as well as producing better recessions than the grid
data.
In conclusion, the analyses carried out for these case studies have produced results to support the
following points. In relation to :
Using alternative conceptual models to derive inflows in River System Simulation Models:
-
The more defined are the stream processes that contribute or impact on the low flows the
better the ability of the model simulate the low flows.
There will be an inflection point at which the effort in modelling these processes will surpass
the return in the improved simulation of low flows.
Using alternative rainfall data sets in Rainfall Runoff Modelling (In particular the Sacramento model):
-
The utilisation of the rainfall stations infilled with data simulates the low flows better than the
gridded rainfall data.
Potentially, the infilling undertaken with surrounding rainfall stations is superior to the
infilling with interpolated data found in the patchpoint rainfall data sets. This was not tested
thoroughly in the Broken River due to the completeness of rainfall data in the principal rainfall
station.
The statistics have assisted in assessing the various options but there are some difficulties in the
interpretation of the statistics and proposed/relative weightings. Therefore they have not been able to be
used to make definitive decisions regarding which scenarios give better low flow responses.
This is similar to what occurs in real world current practices associated with the development of river
models where there is a significant component of subjective compromise to balance the performance
between the different events, timing and antecedent conditions.
24
Hydrology Report: NWC Low Flow Project
To confirm and/or bring clarity to these preliminary findings, more testing including a wider range of
catchments will need to be done.
25
Hydrology Report: NWC Low Flow Project
6
References
Burnash, R.J.C., Ferral, R.L. and McGuire. R.A. (1973). A Generalised Streamflow Simulation System:
Conceptual Modelling for Digital Computers, Joint Federal-State River Forecast Center, U.S. National
Weather Service and California Department of Water Resources, Sacramento, California, U.S.A.
DLWC(1997), “Integrated Quantity Quality Model - User Manual”, Department of Land and Water Conservation,
Sydney.
Kennard M.J., Pusey B.J., Olden J.D., Mackay S.J., Stein J.L., Marsh N.A. (2010). Classification of
natural flow regimes in Australia to support environmental flow management. Freshwater Biology 55,
171-193
Marsh N.A., Stewardson M.J., Kennard M.J. (2003). River Analysis Package, Cooperative Research
Centre for Catchment Hydrology, Monash University, Melbourne
26