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DPIW – SURFACE WATER MODELS
LEVEN & GAWLER CATCHMENT
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
i
DOCUMENT INFORMATION
JOB/PROJECT TITLE Surface Water Hydrological Models for DPIW
CLIENT ORGANISATION Department of Primary Industries and Water
CLIENT CONTACT Bryce Graham
DOCUMENT ID NUMBER WR 2007/08
JOB/PROJECT MANAGER Mark Willis
JOB/PROJECT NUMBER E200690/P202167
Document History and Status
Revision Prepared
by
Reviewed
by
Approved
by
Date
approved
Revision
type
1.0 Mark Willis Dr Fiona
Ling
Crispin
Smythe
April 2007 Final
2.0 Mark Willis Fiona Ling C. Smythe Sept 2007 Final
2.1 Mark Willis Fiona Ling C. Smythe July 2008 Final
Current Document Approval
PREPARED BY Mark Willis
Water Resources Mngt Sign Date
REVIEWED BY Dr Fiona Ling
Water Resources Mngt Sign Date
APPROVED FOR
SUBMISSION
Crispin Smythe
Water Resources Mngt Sign Date
Current Document Distribution List
Organisation Date Issued To
DPIW July 2008 Bryce Graham
The concepts and information contained in this document are the property of Hydro Tasmania.
This document may only be used for the purposes of assessing our offer of services and for inclusion in
documentation for the engagement of Hydro Tasmania. Use or copying of this document in whole or in part for any
other purpose without the written permission of Hydro Tasmania constitutes an infringement of copyright.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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EXECUTIVE SUMMARY
This report is part of a series of reports which present the methodologies and results
from the development and calibration of surface water hydrological models for 26
catchments under both current and natural flow conditions. This report describes the
results of the hydrological model developed for the Leven and Gawler catchment.
A model was developed for the Leven and Gawler catchment that facilitates the
modelling of flow data for three scenarios:
• Scenario 1 – No entitlements (Natural Flow);
• Scenario 2 – with Entitlements (with water entitlements extracted);
• Scenario 3 - Environmental Flows and Entitlements (Water entitlements
extracted, however low priority entitlements are limited by an environmental
flow threshold).
The results from the scenario modelling allow the calculation of indices of hydrological
disturbance. These indices include:
• Index of Mean Annual Flow
• Index of Flow Duration Curve Difference
• Index of Seasonal Amplitude
• Index of Seasonal Periodicity
• Hydrological Disturbance Index
The indices were calculated using the formulas stated in the Natural Resource
Management (NRM) Monitoring and Evaluation Framework developed by SKM for the
Murray-Darling Basin (MDBC 08/04).
A user interface is also provided that allows the user to run the model under varying
catchment demand scenarios. It allows the user to add further extractions to catchments
and see what effect these additional extractions have on the available water in the
catchment of concern. The interface provides sub-catchment summary of flow statistics,
duration curves, hydrological indices and water entitlements data. For information on the
use of the user interface refer to the Operating Manual for the NAP Region Hydrological
Models (Hydro Tasmania 2004).
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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CONTENTS
EXECUTIVE SUMMARY ii
1. INTRODUCTION 6
2. CATCHMENT CHARACTERISTICS 7
3. DATA COMPILATION 9
3.1 Climate data (Rainfall & Evaporation) 9
3.2 Advantages of using climate DRILL data 9
3.3 Transposition of climate DRILL data to local catchment 10
3.4 Comparison of Data Drill rainfall and site gauges 12
3.5 Streamflow data 14
3.6 Irrigation and water usage 14
3.7 Estimation of unlicensed dams 19
3.8 Environmental flows 20
4. MODEL DEVELOPMENT 22
4.1 Sub-catchment delination 22
4.2 Hydstra Model 22
4.2.1 Lake Isandula 24
4.3 AWBM Model 25
4.3.1 Channel Routing 27
4.4 Model Calibrations 28
4.4.1 Factors affecting the reliability of the model calibration. 39
4.4.2 Model Accuracy - Model Fit Statistics 40
4.4.3 Model accuracy across the catchment 44
4.5 Model results 46
4.5.1 Indices of hydrological disturbance 48
4.6 Flood frequency analysis 49
5. REFERENCES 52
5.1 Personal Communications 53
6. GLOSSARY 54
APPENDIX A 56
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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LIST OF FIGURES
Figure 2-1 Sub-catchment boundaries 8
Figure 3-1 Climate Drill Site Locations 11
Figure 3-2 Rainfall and Data Drill Comparisons 13
Figure 3-3 WIMS Water Allocations 18
Figure 4-1 Hydstra Model Schematic 23
Figure 4-2 Australian Water Balance Model Schematic 27
Figure 4-3 Monthly Variation of CapAve Parameter 31
Figure 4-4 Daily time series comparison (ML/d) – Leven Rv. Good fit. 32
Figure 4-5 Daily time series comparison (ML/d) – Leven Rv. Fair fit. 33
Figure 4-6 Daily time series comparison (ML/d) – Leven Rv. Fair fit. 33
Figure 4-7 Daily time series comparison (ML/d) – Gawler Rv. Good fit. 34
Figure 4-8 Daily time series comparison (ML/d) – Gawler Rv. Fair fit. 34
Figure 4-9 Daily time series comparison (ML/d) – Gawler Rv. Fair fit. 35
Figure 4-10 Time Series of Monthly Volumes – Leven River 36
Figure 4-11 Time Series of Monthly Volumes – Gawler River 36
Figure 4-12 Long term average monthly, seasonal and annual comparison plot – Leven River
37
Figure 4-13 Long term average monthly, seasonal and annual comparison plot – Gawler River
38
Figure 4-14 Duration Curve – Daily flow percentage difference – Leven Rv 42
Figure 4-15 Duration Curve – Monthly volume percentage difference – Leven Rv 43
Figure 4-16 Duration Curve – Daily flow percentage difference – Gawler Rv 43
Figure 4-17 Duration Curve – Monthly volume percentage difference- Gawler Rv 44
Figure 4-18 Time Series of Monthly Volumes- Site 821 45
Figure 4-19 Time Series of Monthly Volumes- Site 14227 46
Figure 4-20 Daily Duration Curve – Leven River 47
Figure 4-21 Daily Duration Curve – Gawler River 47
Figure 4-22 Modelled and Observed Flood Frequency Plot - Leven River at Bannon’s Bridge
51
Figure 4-23 Modelled and Observed Flood Frequency Plot Gawler River at West Gawler51
Figure A-1 Forth catchment – monthly volumes at secondary site. 58
Figure A-2 George catchment – monthly volumes at secondary site. 58
Figure A-3 Leven catchment – monthly volumes at secondary site. 59
Figure A-4 Swan catchment – monthly volumes at secondary site. 59
Figure A-5 Montagu catchment – monthly volumes at secondary site. 60
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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LIST OF TABLES
Table 3.1 Data Drill Site Locations 12
Table 3.2 Assumed Surety of Unassigned Records 15
Table 3.3 Sub Catchment High and Low Priority Entitlements 16
Table 3.4 Average capacity for dams less than 20 ML by Neal et al (2002) 20
Table 3.5 Environmental Flows 21
Table 4.1 Boughton & Chiew, AWBM surface storage parameters 25
Table 4.2 Hydstra/TSM Modelling Parameter Bounds 28
Table 4.3 Adopted Calibration Parameters 31
Table 4.4 Long term average monthly, seasonal and annual comparisons – Leven
River 37
Table 4.5 Long term average monthly, seasonal and annual comparisons – Gawler
River 38
Table 4.6 Model Fit Statistics 41
Table 4.7 R2 Fit Description 41
Table 4.8 Hydrological Disturbance Indices 48
Table A-1 Model performance at secondary sites 61
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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1. INTRODUCTION
This report forms part of a larger project commissioned by the Department of Primary
Industries and Water (DPIW) to provide hydrological models for 26 regional catchments.
The main objectives for the individual catchments are:
• To compile relevant data required for the development and calibration of the hydrological model (Australian Water Balance Model, AWBM) for the Leven and Gawler catchment;
• To source over 100 years of daily time-step rainfall and streamflow data for input to the hydrologic model;
• To develop and calibrate the hydrologic model under both natural and current catchment conditions;
• To develop a User Interface for running the model under varying catchment demand scenarios;
• Prepare a report summarising the methodology adopted, assumptions made, results of calibration and validation and description relating to the use of the developed hydrologic model and associated software.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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2. CATCHMENT CHARACTERISTICS
The Leven and Gawler catchment is located in Northern Tasmania and discharges into
Bass Strait at the township of Ulverstone. The catchment boundary provided by DPIW
also includes five small streams that do not flow directly into the Leven or Gawler Rivers
but instead discharge directly into either the Leven estuary or Bass Strait. These
additional streams are known as Masons Creek, Buttons Creek, Skeleton Creek,
Mannings Creek1 and Library Creek 1. For the purpose of this project these have been
considered part of the Leven and Gawler catchment and the combined total area of this
catchment is 684.5 km2.
The headwaters of the catchment start on the slopes of the Black Bluff Range at an
elevation of 1300m. A large proportion of the upper catchment is unpopulated and land
use is a combination of forestry and natural vegetation. The lower part of the catchment
consists of a mixture of agriculture and small (life style) residential allotments. The
catchment includes a number of settlements, the larger ones being Ulverstone, Gunns
Plains, South Riana and North Motton.
Variability in the annual rainfall total across this catchment is significant, mainly due to
the changes in elevation and the varied exposure to the dominant westerly weather
pattern. The lower catchment around Ulverstone, has a typical annual rainfall of 975mm
but the upper catchment around Black Bluff Range has a typical annual rainfall of
1900mm.
Water usage in this catchment is also varied and in total there are 506 registered
(current) entitlements for water extraction on the Water Information Management System
(WIMS Dec 2006). Most of the extractions are concentrated in the lower sub-catchments
and mainly related to agriculture and town water supply. Lake Isandula on the West
Gawler River, which is used as a town water supply, is the largest entitlement. Many of
the upper catchments have few or no registered WIMS entitlements.
For modelling purposes, the Leven and Gawler catchment was divided into 28 sub areas.
The delineation of these areas and the assumed stream routing network is shown in
Figure 2-1.
1 Mannings Creek and Library Creek have been modelled as the one sub-catchment.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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9
6
7
4
14
17
11
16
10
1
15
20
12
3
19
13
18
5
23
262
22
25
28
8
27
24
21
395000
395000
400000
400000
405000
405000
410000
410000
415000
415000
420000
420000
425000
425000
430000
430000
435000
435000
5395000
5395000
5400000
5400000
5405000
5405000
5410000
5410000
5415000
5415000
5420000
5420000
5425000
5425000
5430000
5430000
5435000
5435000
5440000
5440000
5445000
5445000
5450000
5450000
Legend
Sub-catchment boundary
Stream routing network
0 3 6 9 121.5Kilometers
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Figure 2-1 Sub-catchment boundaries
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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3. DATA COMPILATION
3.1 Climate data (Rainfall & Evaporation)
Daily time-step climate data was obtained from the Queensland Department of Natural
Resources & Mines (QDNRM).
The Department provides time series climate drill data from 0.05o x 0.05o (about 5 km x 5
km) interpolated gridded rainfall and evaporation data based on over 6000 rainfall and
evaporation stations in Australia (see www.nrm.qld.gov.au/silo) for further details of climate
drill data.
3.2 Advantages of using climate DRILL data
This data has a number of benefits over other sources of rainfall data including:
• Continuous data back to 1889 (however, further back there are less input sites
available and therefore quality is reduced. The makers of the data set state that
gauge numbers have been somewhat static since 1957, therefore back to 1957
distribution is considered “good” but prior to 1957 site availability may need to be
checked in the study area).
• Evaporation data (along with a number of other climatic variables) is also
included which can be used for the AWBM model. According to the QNRM web
site, all Data Drill evaporation information combines a mixture of the following
data.
1. Observed data from the Commonwealth Bureau of Meteorology (BoM).
2. Interpolated daily climate surfaces from the on-line NR&M climate archive.
3. Observed pre-1957 climate data from the CLIMARC project (LWRRDC QPI-
43). NR&M was a major research collaborator on the CLIMARC project, and
these data have been integrated into the on-line NR&M climate archive.
4. Interpolated pre-1957 climate surfaces. This data set, derived mainly from the
CLIMARC project data, are available in the on-line NR&M climate archive.
5. Incorporation of Automatic Weather Station (AWS) data records. Typically, an
AWS is placed at a user's site to provide accurate local weather
measurements.
For the Leven and Gawler catchment the evaporation data was examined and it was
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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found that prior to 1970 the evaporation information is based on the long term daily
averages of the post 1970 data. In the absence of any reliable long term site data this is
considered to be the best available evaporation data set for this catchment.
3.3 Transposition of climate DRILL data to local catchment
Ten climate Data Drill sites were selected to give good coverage of the Leven and
Gawler catchments. Two sites were at the same location as data used for the Claytons
catchment model.
See Figure 3-1 below for a map of the climate Data Drill sites and Table 3.1 for the
location information.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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_̂
_̂
_̂
_̂ _̂
_̂ _̂
_̂ _̂
_̂
Clayton_07
Clayton_01
LevenGaw_08
LevenGaw_07LevenGaw_06
LevenGaw_05LevenGaw_04
LevenGaw_03
LevenGaw_02
LevenGaw_01
395000
395000
400000
400000
405000
405000
410000
410000
415000
415000
420000
420000
425000
425000
430000
430000
5395000
5395000
5400000
5400000
5405000
5405000
5410000
5410000
5415000
5415000
5420000
5420000
5425000
5425000
5430000
5430000
5435000
5435000
5440000
5440000
5445000
5445000
5450000
5450000
Legend
_̂ Rainfall & Evaporation sitesSub-catchment boundary
0 3 6 9 121.5Kilometers
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Figure 3-1 Climate Drill site locations
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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Table 3.1 Data Drill site locations
Site Longitude Latitude
LevenGaw_01 146:03:00 -41:09:00
Clayton_01 146:09:00 -41:12:00
LevenGaw_02 146:03:00 -41:15:00
LevenGaw_03 145:57:00 -41:18:00
Clayton_07 146:06:00 -41:18:00
LevenGaw_04 145:54:00 -41:24:00
LevenGaw_05 146:03:00 -41:24:00
LevenGaw_06 145:51:00 -41:27:00
LevenGaw_07 146:00:00 -41:27:00
LevenGaw_08 145:48:00 -41:30:00
3.4 Comparison of Data Drill rainfall and site gauges
As rainfall data is a critical input to the modelling process it is important to have
confidence that the Data Drill long term generated time series does in fact reflect what is
being observed within the catchment. Rainfall sites in closest proximity to the Data Drill
locations were sourced and compared. The visual comparison and the R2 value indicate
that there appears to be good correlation between the two, which is to be expected as
the Data Drill information is derived from site data. The annual rainfall totals of selected
Data Drill sites and neighbouring sites for coincident periods are plotted in Figure 3-2.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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0
200
400
600
800
1000
1200
1400
1600
1800
1910
1912
1914
1916
1918
1920
1922
1924
1926
1928
1930
1932
1934
1936
1938
1940
1942
1944
1946
1948
Annaul Rainfall (mm)
Data Drill - Claytons_07 Central Castra - Site 1515R2 = 0.98
0
500
1000
1500
2000
2500
3000
1923
1926
1929
1932
1935
1938
1941
1944
1947
1950
1953
1956
1959
1962
1965
1968
1971
1974
1977
1980
1983
1986
1989
Annaul Rainfall (mm)
Data Drill - Leven_Gawler_05 Nietta South - Site 1567R2 = 0.98
0
200
400
600
800
1000
1200
1400
1600
1800
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
Annaul Rainfall (mm)
Data Drill - Leven_Gawler_01 Penguin - Site 1671R2 = 1.00
Figure 3-2 Rainfall and Data Drill comparisons
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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3.5 Streamflow data
There were two historical streamflow gauge sites identified in the Leven and Gawler
catchment which were potentially suitable as calibration sites.
Site Name
Sub-
catchment
Location
Site No. Period of Record Easting Northing
Gawler River at West Gawler
SC3 14208 24/03/1965 to 01/01/1983
429100 5440800
Leven River at Bannons Bridge
SC4 14207 18/06/1963 to present 423700 5432800
This data was provided by DPIW as a text file in Mega litres per day and both sites were
used for calibration of the model. No significant review of this data has been undertaken
by Hydro Tasmania, as it assumed that DPIW has provided the best available data set.
However, brief investigations of the site rating histories contained on Hydro Tasmania’s
archives indicate the following:
• The Leven River at Bannon’s Bridge site appears to be based on a natural
control with at least 5 ratings covering the 44 years of record. The comments
associated with these ratings suggest that this is a reliable flow record site.
• Site 14208, Gawler at West Gawler, has only one rating covering the 18 years of
record. Comments such as “poor rating” and “natural control tidal” and the
closure of the site in 1983, suggest this may be a less reliable flow record site.
3.6 Irrigation and water usage
Information on the current water entitlement allocations in the catchment was obtained
from DPIW and is sourced from the Water Information Management System (WIMS Dec
2006). The WIMS extractions or licenses in the catchment are of a given Surety (from 1
to 8), with Surety 1-3 representing high priority extractions for modelling purposes and
Surety 4-8 representing the lowest priority. The data provided by DPIW contained a
significant number of sites which had a Surety of 0. DPIW staff advised that in these
cases the Surety should be determined by the extraction “Purpose” and assigned as
follows:
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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Table 3.2 Assumed Surety of unassigned records
Purpose Surety
Aesthetic 6
Aquaculture 6
Commercial 6
Domestic 1
Industrial 6
Irrigation 6
Storage 6
Other 6
Power Generation 6
Recreation 6
Stock and Domestic S & D 1
Stock 1
Water Supply 1
Fire Fighting 1
Dust Proof 6
In total there were 2459.8 ML unassigned entitlements (surety = 0) identified for inclusion
in the surface water model, of which 1658.7 ML were assigned surety 1 and 802.1 ML
assigned surety 6.
DPIW staff also advised that the water extraction information provided should be filtered
to remove the following records:
• Extractions relating to fish farms should be omitted as this water is returned to the
stream. These are identified by a Purpose name called “fish farm” or “Acquacult”.
There were no fish farms identified in this catchment.
• The extraction data set includes a “WE_status” field where only “current” and
“existing” should be used for extractions. All other records, for example deleted,
deferred, transferred, suspended and proposed, should be omitted.
When modelling Scenario 3 (Environmental flows and Entitlements), water will only be
available for Low Priority entitlements after environmental flow requirements have been
met.
Following communications with DPIW staff, allowances for extractions not yet included in
the WIMS (Dec 2006) were made. DPIW advised that in the Gawler catchment, an
additional 2659ML should be allowed. For the Leven Catchment it was advised that an
allowance based on the Gawler surety5/surety 6 ratio should be used and this was
calculated to be 3786 ML. These allowances were proportioned over the sub-
catchments based on existing WIMS entitlements. It was agreed that for the purpose of
this calculation, the large extractions relating to Lake Isandula should be excluded from
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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this apportionment and sub-catchments 26, 27and 2 deemed to lie within the Gawler
catchment.
Allowances for unlicensed dam extractions are covered in Section 3.7.
A summary table of total entitlement volumes on a monthly basis by sub-catchment is
provided below in Table 3.3 and in the Catchment User Interface. A map of the water
allocations in the catchment is shown in Figure 3-3.
Table 3.3 Sub Catchment high and low priority entitlements
Water Entitlements Summarised - Monthly Demand (ML) for each Subarea & Month
Subcatch Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
High Priority Entitlements
SC1 14.97 13.52 14.97 14.49 0.50 0.48 0.50 0.50 0.48 14.97 14.49 14.97 105
SC2 89.07 80.45 89.07 86.20 11.06 10.71 11.06 11.06 10.71 89.07 86.20 89.07 664
SC3 78.59 70.98 78.59 76.05 21.03 20.36 21.03 21.03 20.36 78.59 76.05 78.59 641
SC4 58.70 53.02 58.70 56.80 11.03 10.68 11.03 11.03 10.68 63.33 61.29 58.70 465
SC5 7.13 6.44 7.13 6.90 3.94 3.81 3.94 3.94 3.81 7.13 6.90 7.13 68
SC6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC7 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC8 4.29 3.87 4.29 4.15 1.13 1.10 1.13 1.13 1.10 4.29 4.15 4.29 35
SC9 236.67 213.76 236.67 229.03 5.41 5.23 5.41 5.41 5.23 236.67 229.03 236.67 1,645
SC10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC14 1.80 1.63 1.80 1.75 0.00 0.00 0.00 0.00 0.00 1.80 1.75 1.80 12
SC15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC16 0.70 0.64 0.70 0.68 0.28 0.27 0.28 0.28 0.27 0.70 0.68 0.70 6
SC17 185.64 167.67 185.64 179.65 6.11 5.91 6.11 6.11 5.91 185.64 179.65 185.64 1,300
SC18 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC20 2.74 2.48 2.74 2.65 0.92 0.89 0.92 0.92 0.89 2.74 2.65 2.74 23
SC21 178.83 161.52 178.83 173.06 174.52 168.89 174.52 174.52 168.89 178.83 173.06 178.83 2,084
SC22 32.07 28.96 32.07 31.03 2.57 2.48 2.57 2.57 2.48 32.07 31.03 32.07 232
SC23 23.06 20.83 23.06 22.32 9.65 9.34 9.65 9.65 9.34 23.06 22.32 23.06 205
SC24 17.59 15.88 17.59 17.02 4.63 4.48 4.63 4.63 4.48 17.59 17.02 17.59 143
SC25 14.52 13.11 14.52 14.05 2.60 2.52 2.60 2.60 2.52 14.52 14.05 14.52 112
SC26 120.81 109.12 120.81 116.91 15.84 15.33 15.84 15.84 15.33 120.81 116.91 120.81 904
SC27 39.72 35.88 39.72 38.44 3.13 3.03 3.13 3.13 3.03 39.72 38.44 39.72 287
SC28 74.78 67.54 74.78 72.36 15.97 15.45 15.97 15.97 15.45 74.78 72.36 74.78 590
Total 1,182 1,067 1,182 1,144 290 281 290 290 281 1,186 1,148 1,182 9,523
Low Priority Entitlements
SC1 14.90 13.45 14.90 14.41 5.54 5.36 5.54 5.54 5.36 5.54 15.31 14.90 121
SC2 5.85 5.28 5.85 5.66 81.61 83.04 85.81 85.81 83.04 85.81 77.74 5.85 611
SC3 26.24 23.70 26.24 25.39 33.77 32.68 33.77 33.77 32.68 33.77 28.68 26.24 357
SC4 42.17 38.09 42.13 38.86 25.00 24.19 25.00 25.00 24.19 25.00 27.88 40.35 378
SC5 0.00 0.00 0.00 0.00 3.40 3.29 3.40 3.40 3.29 3.40 3.29 0.00 24
SC6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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SC7 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC8 0.00 0.00 0.00 0.00 4.39 4.25 4.39 4.39 4.25 4.39 4.25 0.00 30
SC9 378.91 342.24 375.28 356.80 6.06 5.86 6.06 6.06 5.86 6.06 20.78 372.65 1,883
SC10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC14 0.85 4.77 5.28 4.09 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 15
SC15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC16 0.00 0.00 0.00 0.00 0.65 0.63 0.65 0.65 0.63 0.65 0.63 0.00 5
SC17 230.62 208.30 230.62 223.18 48.25 46.69 48.25 48.25 46.69 48.25 84.81 230.53 1,494
SC18 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC20 1.39 1.25 1.39 1.34 0.87 0.84 0.87 0.87 0.84 0.87 0.84 1.39 13
SC21 54.36 49.10 54.36 52.60 59.93 57.99 59.93 59.93 57.99 59.93 57.03 54.36 678
SC22 2.66 2.40 2.66 2.57 35.38 34.24 35.38 35.38 34.24 35.38 28.45 2.66 251
SC23 0.00 0.00 0.00 0.00 5.00 4.84 5.00 5.00 4.84 5.00 4.84 0.00 35
SC24 0.00 0.00 0.00 0.00 10.95 10.60 10.95 10.95 10.60 10.95 10.60 0.00 76
SC25 1.06 0.96 1.06 1.03 15.04 14.55 15.04 15.04 14.55 15.04 10.48 1.06 105
SC26 46.36 42.12 46.63 45.13 88.91 86.04 88.91 88.91 86.04 89.45 82.70 46.30 838
SC27 12.19 11.01 12.19 11.80 36.84 35.65 36.84 36.84 35.65 36.84 35.65 12.19 314
SC28 8.31 7.51 8.31 8.05 43.40 42.00 43.40 43.40 42.00 43.40 37.37 8.31 335
Total 826 750 827 791 505 493 509 509 493 510 531 817 7,560
All Entitlements
SC1 29.87 26.98 29.87 28.90 6.04 5.85 6.04 6.04 5.85 20.51 29.79 29.87 226
SC2 94.92 85.74 94.92 91.86 92.67 93.75 96.87 96.87 93.75 174.88 163.94 94.92 1,275
SC3 104.82 94.68 104.82 101.44 54.80 53.03 54.80 54.80 53.03 112.35 104.73 104.82 998
SC4 100.86 91.10 100.83 95.66 36.03 34.87 36.03 36.03 34.87 88.33 89.17 99.05 843
SC5 7.13 6.44 7.13 6.90 7.34 7.11 7.34 7.34 7.11 10.54 10.20 7.13 92
SC6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC7 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC8 4.29 3.87 4.29 4.15 5.52 5.35 5.52 5.52 5.35 8.68 8.40 4.29 65
SC9 615.58 556.01 611.95 585.83 11.46 11.09 11.46 11.46 11.09 242.72 249.81 609.32 3,528
SC10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC14 2.66 6.40 7.09 5.84 0.00 0.00 0.00 0.00 0.00 1.80 1.75 1.80 27
SC15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC16 0.70 0.64 0.70 0.68 0.93 0.90 0.93 0.93 0.90 1.36 1.31 0.70 11
SC17 416.26 375.98 416.26 402.83 54.35 52.60 54.35 54.35 52.60 233.89 264.46 416.17 2,794
SC18 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 -
SC20 4.13 3.73 4.13 4.00 1.79 1.73 1.79 1.79 1.73 3.61 3.50 4.13 36
SC21 233.19 210.62 233.19 225.66 234.45 226.89 234.45 234.45 226.89 238.76 230.09 233.19 2,762
SC22 34.73 31.37 34.73 33.61 37.95 36.72 37.95 37.95 36.72 67.45 59.48 34.73 483
SC23 23.06 20.83 23.06 22.32 14.64 14.17 14.64 14.64 14.17 28.06 27.16 23.06 240
SC24 17.59 15.88 17.59 17.02 15.58 15.08 15.58 15.58 15.08 28.54 27.62 17.59 219
SC25 15.58 14.07 15.58 15.08 17.64 17.07 17.64 17.64 17.07 29.56 24.53 15.58 217
SC26 167.17 151.24 167.44 162.04 104.75 101.37 104.75 104.75 101.37 210.26 199.61 167.11 1,742
SC27 51.91 46.88 51.91 50.23 39.97 38.68 39.97 39.97 38.68 76.56 74.09 51.91 601
SC28 83.09 75.05 83.09 80.41 59.37 57.45 59.37 59.37 57.45 118.17 109.73 83.09 926
Total 2,008 1,818 2,009 1,934 795 774 799 799 774 1,696 1,679 1,998 17,084
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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9
6
7
4
14
17
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16
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15
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262
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395000
395000
400000
400000
405000
405000
410000
410000
415000
415000
420000
420000
425000
425000
430000
430000
5395000
5395000
5400000
5400000
5405000
5405000
5410000
5410000
5415000
5415000
5420000
5420000
5425000
5425000
5430000
5430000
5435000
5435000
5440000
5440000
5445000
5445000
5450000
5450000
Legend
Sub-catchment boundary
!( Water Allocations
0 2.5 5 7.5 101.25Kilometers
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Figure 3-3 WIMS Water allocations
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
19
3.7 Estimation of unlicensed dams
Under current Tasmanian law, a dam permit is not required for a dam if it is not on a
watercourse and holds less than 1ML of water storages (prior to 2000 it was 2.5 ML),
and only used for stock and domestic purposes. Therefore there are no records for
these storages. The storage volume attributed to unlicensed dams was estimated by
analysis of aerial photographs and the methodology adopted follows:
• Aerial photographs were analysed. GoogleEarth was selected as the
source for the aerial photographs because in this case the majority of the
catchment was covered by high resolution photography. The GoogleEarth
photos covering this catchment were based on 2003 to 2006. The number
of dams of any size in six selected sub-catchments were counted by eye.
Based on these numbers and the DPIW entitlements data a ratio of
unlicensed to licensed dams was calculated for each sub-catchment. The
results were, 0.23, 1.25, 0.33, 0.32, 0.45 and 0.33 unlicensed dams per
licensed dam, with an average of 0.49. This compares favourably with the
Panatana catchment which had an average of 0.41.
• Using the average ratio of 0.49 unlicensed dams per licensed dam an
estimate of the number of unlicensed dams in the uncounted sub-
catchments was determined. In total it is estimated that there are 163
unlicensed dams throughout the catchment.
• It was assumed most of these dams would be legally unlicensed dams
(less than 1 ML and not situated on a water course) however, it was
assumed that there would be a proportion of illegal unlicensed dams up to
20ML in capacity. Some of these were visible on the aerial photographs.
• A frequency distribution of farm dam sizes presented by Neal et al (2002)
for the Marne River Catchment in South Australia showed that the average
dam capacity for dams less than 20 ML was 1.4 ML (Table 3.4).
• Following discussions with DPIW staff, the unlicensed dam demand was
assumed to be 100%. The assumption is that all unlicensed dams will be
empty at the start of May and will fill over the winter months, reaching 100%
capacity by the end of September.
• Assuming this dam size distribution is similar to the distribution of the study
catchment in South Australia, then the total volume of unlicensed dams can
be estimated as 228 ML (163 * 1.4ML). This equates to 0.33 ML of
unlicensed dams/km2, however large portions of the catchment are
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
20
undeveloped and accordingly this value varies significantly from one sub-
catchment to another. The total volume of existing permitted dams
extractions in the study catchment is 4988 ML. Therefore the 228 ML of
unlicensed dams equates to approximately 4% of the total dam extractions
from the catchment.
Table 3.4 Average capacity for dams less than 20 ML by Neal et al (2002)
Size Range (ML)
Average Volume (ML)
Number of Dams
Total Volume (ML)
0 - 0.5 0.25 126 31.5
0.5 - 2 1.25 79 98.75
2 - 5 3.5 13 45.5
5 - 10 7.5 7 52.5
10 - 20 15 6 90
27.5 231 318.25
Average Dam Volume: 1.4 ML
3.8 Environmental flows
One of the modelling scenarios (Scenario 3) was to account for environmental flows
within the catchment. DPIW advised, that for the Leven and Gawler catchment, they
currently do not have environmental flow requirements defined. In the absence of this
information it was agreed that the calibrated catchment model would be run in the
Modelled – No entitlements (Natural) scenario and the environmental flow would be
assumed to be:
• The 20th percentile for each sub-catchment during the winter period (01May to
31st Oct).
• The 30th percentile for each sub-catchment during the summer period (01 Nov –
30 April).
The Modelled – No entitlements (Natural) scenario was run from 01/01/1900 to
01/01/2006.
A summary table of the environmental flows on a monthly breakdown by sub-catchment
is provided below in Table 3.3 and in the Catchment User Interface.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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Table 3.5 Environmental Flows
Sub-catchment Area (km2)
Environmental Flow (ML/d) Per Month at each subcatchment
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average
SC1 18.9 213.5 122.1 129.5 333.3 594.5 1161.2 1492.1 1486.2 1305.3 815.7 707.2 427.5 732.3
SC2 9.1 0.3 0.3 0.3 0.7 1.0 2.1 6.7 8.6 7.6 3.3 1.8 0.8 2.8
SC3 12.9 6.2 4.7 5.4 9.9 15.0 39.9 96.5 125.6 100.0 56.7 34.4 15.9 42.5
SC4 30.6 202.6 115.1 127.8 331.1 595.6 1146.1 1449.1 1390.9 1264.9 790.7 668.8 418.0 708.4
SC5 10.5 2.4 2.1 2.3 3.9 5.3 17.1 42.8 51.8 41.0 24.7 13.4 6.1 17.8
SC6 37.5 25.7 13.7 16.4 53.1 79.8 126.4 139.7 139.6 127.1 87.0 74.7 54.3 78.1
SC7 32.5 15.4 8.4 8.4 28.6 53.2 95.9 108.0 106.2 95.6 65.1 54.3 35.2 56.2
SC8 6.1 2.1 1.8 2.0 3.5 4.7 14.5 37.0 45.2 34.3 21.7 11.8 5.3 15.3
SC9 52.4 192.5 107.8 126.6 327.8 594.7 1096.5 1348.5 1284.0 1148.4 742.9 607.8 404.0 665.1
SC10 38.6 103.6 59.9 61.6 199.1 338.6 580.5 636.7 641.1 593.9 398.3 335.0 227.4 348.0
SC11 38.7 11.3 6.3 5.9 11.9 29.4 77.8 103.5 104.9 91.2 59.6 44.3 23.9 47.5
SC12 29.0 33.4 18.2 20.0 66.6 106.7 180.4 193.4 191.2 177.9 120.2 103.4 71.3 106.9
SC13 25.1 12.1 6.5 7.3 20.8 37.6 66.0 87.7 86.7 69.9 46.0 37.2 25.7 41.9
SC14 46.7 160.7 94.6 104.3 293.1 489.6 902.3 1088.5 1031.4 904.6 607.4 491.8 334.6 541.9
SC15 36.5 129.2 73.4 76.1 232.8 411.1 765.7 873.1 877.9 763.2 516.9 423.7 278.1 451.8
SC16 39.7 185.8 103.6 122.7 323.7 563.4 1031.2 1256.4 1173.4 1056.6 700.6 567.4 384.8 622.5
SC17 42.5 196.5 112.0 127.1 329.8 595.3 1126.6 1392.5 1375.2 1216.5 781.7 641.8 412.7 692.3
SC18 21.4 39.6 21.1 24.8 79.5 121.5 200.1 218.4 213.6 200.3 135.3 116.0 82.8 121.1
SC19 25.1 17.4 9.2 11.1 36.0 53.6 84.9 93.8 93.9 85.2 58.5 50.2 36.7 52.5
SC20 32.5 209.0 119.9 128.6 332.4 595.8 1165.9 1492.5 1436.3 1296.6 801.6 693.4 422.6 724.6
SC21 2.8 2.6 2.2 2.4 4.2 5.8 18.0 45.6 55.9 44.1 26.3 14.6 6.8 19.0
SC22 15.3 5.7 4.4 4.9 8.7 13.0 37.0 92.5 116.2 92.1 50.7 31.1 14.3 39.2
SC23 19.4 1.6 1.3 1.6 2.7 3.6 12.0 31.1 34.7 27.6 17.3 8.7 4.2 12.2
SC24 5.9 0.5 0.4 0.5 0.8 1.1 3.3 9.1 10.2 8.1 5.0 2.6 1.2 3.6
SC25 14.4 1.2 1.0 1.2 2.0 2.7 8.5 22.9 25.7 20.8 12.9 6.4 3.2 9.0
SC26 19.1 0.6 0.7 0.6 1.4 2.0 3.8 12.3 16.2 14.1 5.6 3.4 1.6 5.2
SC27 7.1 0.2 0.2 0.2 0.5 0.8 1.4 4.5 6.1 5.3 2.1 1.3 0.6 1.9
SC28 14.0 0.9 0.5 0.5 0.9 1.5 3.7 7.9 11.3 9.6 4.5 3.3 1.6 3.9
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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4. MODEL DEVELOPMENT
4.1 Sub-catchment delineation
Sub-catchment delineation was performed using CatchmentSIM GIS software.
CatchmentSIM is a freely available 3D-GIS topographic parameterisation and hydrologic
analysis model. The model automatically delineates watershed and sub-catchment
boundaries, generalises geophysical parameters and provides in-depth analysis tools to
examine and compare the hydrologic properties of sub-catchments. The model also
includes a flexible result export macro language to allow users to fully couple
CatchmentSIM with any hydrologic modelling package that is based on sub-catchment
networks.
For the purpose of this project, CatchmentSIM was used to delineate the catchment,
break it up into numerous sub-catchments, determine their areas and provide routing
lengths between them.
These outputs were manually checked to ensure they accurately represented the
catchment. If any minor modifications were required these were made manually to the
resulting model.
For more detailed information on CatchmentSIM see the CatchmentSIM Homepage
www.toolkit.net.au/catchsim/
4.2 Hydstra Model
A computer simulation model was developed using Hydstra Modelling. The sub-
catchments, described in Figure 2-1, were represented by model “nodes” and
connected together by “links”. A schematic of this model is displayed in Figure 4-1.
The flow is routed between each sub-catchment, through the catchment via a channel
routing function.
The rainfall and evaporation is calculated for each subcatchment using inverse-
distance gauge weighting. The gauge weights were automatically calculated at the
start of each model run. The weighting is computed for the centroid of the sub-
catchment. A quadrant system is drawn, centred on the centroid. A weight for the
closest gauge in each quadrant is computed as the inverse, squared, distance between
the gauge and centroid. For each time step and each node, the gauge weights are
applied to the incoming rainfall and evaporation data.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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The AWBM Two Tap rainfall/runoff model was used to calculate the runoff for each sub-
catchment separately. This was chosen over the usual method of a single AWBM model
for the whole catchment as it more accurately distributes the runoff and base flow
spatially over the catchment.
The flow is routed between each sub-catchment, through the catchment via a channel
routing function.
Figure 4-1 Hydstra Model schematic
As previously mentioned this model includes 4 separate sub-catchments which flow
directly into Bass Strait and therefore are not direct tributaries to the Leven or Gawler
Rivers.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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4.2.1 Lake Isandula
A significant lake known as Lake Isandula was identified during the creation of the
Gawler catchment model and is located in sub-catchment 21. This dam is owned by
Cradle Coast Water Authority and has an influence on the flow regime in the Gawler
River. No information relating to historic lake discharges was identified. In the absence
of observed lake discharge data, discussions with DPIW staff on the appropriate way to
model this lake resulted in the following decisions:
• Scenario 1, “No Entitlements (Defines ‘Natural’ Flows)” will model the catchment
with no dam or lake present for all of record.
• Both the Scenario 2 “with Entitlements (extraction not limited by Env.Flows)” and
Scenario 3, “Environmental Flows & Entitlements (‘Low Priority Ents. Limited by
Env Flows’)” scenarios will model the catchment with:
o No dam or lake present in the model prior to and during its construction in
1966.
o From 1967 onwards, the lake will be modelled using a basic volume
balance rule assuming the following:
� Lake volume will be 400 ML (from DPIW dams database) and at
full supply level at start of model.
� Water entitlements falling within the Lake Isandula sub-catchment
(SC21) will be extracted from the lake volume.
� Inflows in excess of the lake volume will be discharged
downstream as spill.
� If the Environmental Flows & Entitlements scenario is selected
then a flow will be released downstream equal to the
environmental flow specified in the user interface, for the Lake
Isandula sub-catchment (SC 21). However when the modelled
inflow to SC21 is less than the specified environmental flow, the
downstream release will be reduced to equal SC21 inflow. This
has been done to stop excessive draw down of the lake in periods
of low inflow.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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4.3 AWBM Model
The AWBM Two Tap model (Parkyn & Wilson 1997) is a relatively simple water balance
model with the following characteristics:
• it has few parameters to fit,
• the model representation is easily understood in terms of the actual outflow
hydrograph,
• the parameters of the model can largely be determined by analysis of the
outflow hydrograph,
• the model accounts for partial area rainfall-run-off effects,
• runoff volume is relatively insensitive to the model parameters.
For these reasons parameters can more easily be transferred to ungauged catchments.
The AWBM routine used in this study is the Boughton Revised AWBM model (Boughton,
2003), which reduces the three partial areas and three surface storage capacities to
relationships based on an average surface storage capacity.
Boughton & Chiew (2003) have shown that when using the AWBM model, the total
amount of runoff is mainly affected by the average surface storage capacity and much
less by how that average is spread among the three surface capacities and their partial
areas. Given an average surface storage capacity (Ave), the three partial areas and the
three surface storage capacities are found by;
Table 4.1 Boughton & Chiew, AWBM surface storage parameters
Partial area of S1 A1=0.134
Partial area of S2 A2=0.433
Partial area of S3 A3=0.433
Capacity of S1 C1=(0.01*Ave/A1)=0.075*Ave
Capacity of S2 C2=(0.33*Ave/ A2)=0.762*Ave
Capacity of S3 C3=(0.66*Ave/ A3)=1.524*Ave
The AWBM routine produces two outputs; direct run-off and base-flow. Direct run-off is
produced after the content of any of the soil stores is exceeded; it can be applied to the
stream network directly or by catchment routing across each subcatchment. Base-flow is
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
26
usually supplied unrouted directly to the stream network, at a rate proportional to the
water depth in the ground water store. The ground water store is recharged from a
proportion of excess rainfall from the three surface soil storages.
Whilst the AWBM methodology incorporates an account of base-flow, it is not intended
that the baseflow prediction from the AWBM model be adopted as an accurate estimate
of the baseflow contribution. The base flow in the AWBM routine is based on a simple
model and does not specifically account for attributes that affect baseflow such as
geology and inter-catchment ground water transfers. During the model calibration the
baseflow infiltration and recession parameters are used to ensure a reasonable fit with
the observed surface water information.
The AWBM processes are shown below in Figure 4-2;
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
27
Figure 4-2 Australian Water Balance Model schematic
4.3.1 Channel Routing
A common method employed in nonlinear routing models is a power function storage
relation.
S = K.Qn
K is a dimensional empirical coefficient, the reach lag (time). In the case of Hydstra/TSM
Modelling:
α
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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and
Li = Channel length (km)
α = Channel Lag Parameter
n = Non-linearity Parameter
Q = Outflow from Channel Reach (ML/day)
A reach length factor may be used in the declaration of α to account for varying reach lag
for individual channel reaches. eg. α.fl where fl is a length factor.
Parameters required by Hydstra/TSM Modelling and their legal bounds are:
Table 4.2 Hydstra/TSM Modelling Parameter Bounds
α Channel Lag Parameter Between 0.0 and 5.0
L Channel Length (km) Greater than 0.0 (km)
n Non-linearity Parameter Between 0.0 and 1.0
4.4 Model Calibrations
Calibration was achieved by adjusting catchment parameters so that the modelled data
best replicates the record at the two sites selected for calibration (for information on
these sites, refer to Section 3.5). The best fit of parameters was achieved by comparing
the monthly, seasonal and annual volumes over the entire calibration period, using
regression statistics and using practitioner judgment when observing daily and monthly
time series comparisons. It should be noted that during the calibration process matching
of average long term monthly volumes (flows) was given the highest priority and
matching of peak flood events and daily flows was given lower priority. Further
discussion of the model calibration fit is given in Section 4.4.2
The calibration process can best be understood as attempting to match the modelled
calibration flow (MCF) to the observed flow record. The MCF can be described as:
MCF = MNEM - (WE x TPRF)
Where:
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MCF = Modelled Calibration Flow
MNEM = Modelled - No Entitlements (Modified). *
WE = Water Entitlements
TPRF = Time Period Reduction Factor
* Refer to Glossary for additional explanation of these terms
Water entitlements were included in the calibration model and adjusted to the time period
of calibration by applying a Time Period Reduction Factor (TPRF). The TPRF was
calculated by a method developed in the Tasmanian State of the Environment report
(1996). This states that water demand has increased by an average of 6% annually over
the last 4 decades. However, following discussions with DPIW the TPRF was capped at
50% of the current extractions if the mid year of the calibration period was earlier than
1994.
In the Leven catchment, data from the period 01/01/1987 to 01/09/2006 was selected at
Leven at Bannon’s Bridge (site 14207) for calibration. A water entitlements reduction
factor of 56% was applied to all extractions as the mid year of this period was deemed to
be 1996.
In the Gawler catchment, data from the period 25/03/1965 to 01/01/1983 was selected at
Gawler at West Gawler (site 14208) for calibration. A water entitlements reduction factor
of 50% was applied to all extractions as the mid year of this period was deemed to be
1973.
The model was calibrated to the observed flow as stated in the formula MCF = MNEM -
(WE x TPRF). Other options of calibration were considered, including adding the water
entitlements to the observed flow. However, the chosen method is considered to be the
better option as it preserves the observed flow and unknown quantities are not added to
the observed record. The chosen method also preserves the low flow end of the
calibration, as it does not assume that all water entitlements can be met at any time.
In the absence of information on daily patterns of extraction, the model assumes that
water entitlements are extracted at a constant daily flow for each month. For each daily
time step of the model if extractions cannot be met, the modelled outflows are restricted
to a minimum value of zero and the remaining water required to meet the entitlement is
lost. Therefore the MCF takes account of very low flow periods where the water
entitlements demand can not be met by the flow in the catchment. Table 4.4 and Table
4.5 show the monthly water entitlements (demand) used in the calibration upstream of
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the calibration sites.
The adopted calibrated model parameters are shown in Table 4.3. These calibration
parameters are adopted for all three scenarios in the user interface. Although it is
acknowledged that some catchment characteristics such as land use and vegetation will
have changed over time, it is assumed that the rainfall run-off response defined by these
calibration parameters has not changed significantly over time and therefore it is
appropriate to apply these parameters to all three scenarios.
To achieve a better fit of seasonal volumes, the normally constant store parameter
CapAve has been made variable and assigned a seasonal profile as shown in Figure
4-3. Two sets of CapAve profiles were applied across the catchment to achieve an
optimum volume balance at both calibration locations. The adopted name and extent of
each CapAve parameter is itemised below.
• CapAve: All of the Leven River and individual (separate) streams included in
subcatchment 28
• CapAve_G: All of the Gawler River and individual (separate) streams included in
subcatchments 26, 27 and 2.
It was found that the calibration fit parameters derived for the Leven catchment generally
translated well to the Gawler catchment. However, to achieve the best fit at both
calibration locations, it was also necessary to vary the calibration parameter K1 between
catchments. The adopted name of K1 and the specific location assignment is itemised
below.
• K1: All of the Leven River catchment and individual (separate) streams
included in sub-catchment 28.
• K1_G: All of the Gawler River and individual (separate) streams included in
sub-catchments 26, 27 and 2.
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Table 4.3 Adopted Calibration Parameters
PARAMETER Leven VALUE
PARAMETER Gawler VALUE
INFBase 0.75 INFBase 0.75
K1 0.97 K1_G 0.95
K2 0.98 K2 0.98
GWstoreSat 70 GWstoreSat 70
GWstoreMax 100 GWstoreMax 100
H_GW 90 H_GW 90
EvapScaleF 1 EvapScaleF 1
Alpha 3 Alpha 3
n 0.8 n 0.8
CapAve Variable CapAve_G Variable
0
50
100
150
200
250
1 2 3 4 5 6 7 8 9 10 11 12Month
CapeAve
Gawler CapAve
Leven CapAve
Figure 4-3 Monthly Variation of CapAve Parameter
Results of the calibration are shown in the plots and tables that follow in this section. In
all comparisons the “Modelled Calibration Flow” (refer to previous description) has
been compared against the observed flow at the calibration location.
Daily time series plots of three discrete calendar years (Figure 4-4 to Figure 4-9) have
been displayed for the calibration location, showing a range of relatively low to high
inflow years and a range of calibration fits. The general fit for each annual plot is
described in the caption text. This indication is a visual judgement of the relative model
performance for that given year compared to the entire observed record. There is also
a goodness of fit statistic (R2) shown on each plot to assist in the judgement of the
model performance.
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The catchment average precipitation as input to the model is also displayed to provide
a representation of the relative size of precipitation events through the year. Note that
the precipitation trace is plotted on an offset, secondary scale. Overall the daily time
series plots show a good to fair response to rainfall events and a good to fair
agreement with hydrograph shape. The water entitlements for both calibration
locations are relatively small and for the Leven River, for plotting purposes, the water
entitlements have been multiplied by a factor of 10.
The monthly time series, over the whole period of observed record, are plotted in
Figure 4-10 to Figure 4-11 and overall shows a good comparison between modelled
and observed totals for both calibration locations.
The monthly, seasonal and annual volume balances for the whole period of calibration
record are presented in Figure 4-12 to Figure 4-13 and Table 4.4 to Table 4.5. The
demand values shown represent the adopted total water entitlements upstream of the
gauging site. It has been included to provide a general indication of the relative
amount of water being extracted from the river.
0
2000
4000
6000
8000
10000
12000
14000
16000
01/1994 03/1994 05/1994 07/1994 09/1994 11/1994 01/1995
-100
-80
-60
-40
-20
0
20
40
60Precipitation Modelled Calibration Flow Observed
R2 = 0.82
Figure 4-4 Daily time series comparison (ML/d) – Leven Rv. Good fit.
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0
5000
10000
15000
20000
25000
01/2000 03/2000 05/2000 07/2000 09/2000 11/2000 01/2001
-100
-80
-60
-40
-20
0
20
40
60Precipitation Modelled Calibration Flow Observed
R2 = 0.66
Figure 4-5 Daily time series comparison (ML/d) – Leven Rv. Fair fit.
0
2000
4000
6000
8000
10000
12000
14000
01/1996 03/1996 05/1996 07/1996 09/1996 11/1996 01/1997
-100
-80
-60
-40
-20
0
20
40
60Precipitation Modelled Calibration Flow Observed
R2 = 0.69
Figure 4-6 Daily time series comparison (ML/d) – Leven Rv. Fair fit.
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0
200
400
600
800
1000
1200
1400
1600
1800
01/1968 03/1968 05/1968 07/1968 09/1968 11/1968 01/1969
-100
-80
-60
-40
-20
0
20
40
60Precipitation Modelled Calibration Flow Observed
R2 = 0.85
Figure 4-7 Daily time series comparison (ML/d) – Gawler Rv. Good fit.
0
500
1000
1500
2000
2500
01/1975 03/1975 05/1975 07/1975 09/1975 11/1975 01/1976
-100
-80
-60
-40
-20
0
20
40
60Precipitation Modelled Calibration Flow Observed
R2 = 0.66
Figure 4-8 Daily time series comparison (ML/d) – Gawler Rv. Fair fit.
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0
200
400
600
800
1000
1200
01/1971 03/1971 05/1971 07/1971 09/1971 11/1971 01/1972
-100
-80
-60
-40
-20
0
20
40
60Precipitation Modelled Calibration Flow Observed
R2 = 0.77
Figure 4-9 Daily time series comparison (ML/d) – Gawler Rv. Fair fit.
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0
20000
40000
60000
80000
100000
120000
140000
160000
180000
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Monthly Volume (ML)
Observed - Leven River - site 14207 Modelled Calibration Flow
R2 = 0.95
Figure 4-10 Time Series of Monthly Volumes – Leven River
0
5000
10000
15000
20000
1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982
Monthly Volume (ML)
Observed - Gawler at WG - site 14208Modelled Calibration Flow R
2 = 0.92
Figure 4-11 Time Series of Monthly Volumes – Gawler River
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0
500
1000
1500
2000
2500
3000
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
WINTER
SUMMER
ANNUAL
Average Flow (ML/Day)
Observed
Modelled Calibration Flow
Modelled -
Modelled No Entitlements (Natural)Demand x10
Figure 4-12 Long term average monthly, seasonal and annual comparison plot –
Leven River
MONTH Observed
Modelled Calibration
Flow
Scenario 1 Modelled –No Entitlements (Natural) Demand
2
Jan 430.93 434.53 455.02 20.52
Feb 301.71 301.68 322.24 20.60
Mar 278.91 288.58 309.09 20.54
Apr 601.19 605.58 626.03 20.36
May 1053.03 1064.16 1066.29 1.86
Jun 1861.99 1894.49 1896.35 1.86
Jul 2486.62 2477.47 2479.33 1.86
Aug 2569.81 2569.05 2570.91 1.86
Sep 2188.37 2182.69 2184.54 1.86
Oct 1540.84 1528.46 1538.63 10.26
Nov 1032.81 1004.18 1015.48 11.32
Dec 580.19 575.25 595.46 20.36
WINTER 1950.11 1952.72 1956.01 3.26
SUMMER 537.62 534.97 553.89 18.95
ANNUAL 1243.87 1243.84 1254.95 11.10
WINTER from May to Oct, SUMMER from Nov - Apr.
Table 4.4 Long term average monthly, seasonal and annual comparisons –
Leven River
2 The demand value includes all extraction potential upstream of calibration site with a 56% time period reduction factor
applied.
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0
50
100
150
200
250
300
350
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
WINTER
SUMMER
ANNUAL
Average Flow (ML/Day)
Observed
Modelled Calibration Flow
Modelled No Entiltlements
(Natural)
Demand
Figure 4-13 Long term average monthly, seasonal and annual comparison plot –
Gawler River
Table 4.5 Long term average monthly, seasonal and annual comparisons –
Gawler River
MONTH Observed Modelled-Calibration
Flow
Scenario 1 Modelled –No Entitlements (Natural)
Demand 3
Jan 27.35 27.14 33.13 7.10
Feb 17.84 18.03 24.22 7.10
Mar 19.53 19.85 25.95 7.10
Apr 34.21 34.71 42.23 7.10
May 92.60 92.03 98.07 6.26
Jun 130.69 130.63 136.67 6.26
Jul 229.63 229.20 236.35 6.26
Aug 282.62 282.44 288.69 6.26
Sep 213.54 215.26 221.51 6.26
Oct 137.78 135.03 143.41 8.45
Nov 70.70 70.93 78.56 8.20
Dec 42.99 41.85 48.76 7.10
WINTER 181.14 180.76 187.45 6.62
SUMMER 35.43 35.42 42.14 7.29
ANNUAL 108.29 108.09 114.80 6.95
WINTER from May to Oct, SUMMER from Nov - Apr.
3 The demand value includes all extraction potential upstream of calibration site with a 50% time period reduction factor
applied.
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4.4.1 Factors affecting the reliability of the model calibration.
Regardless of the effort undertaken to prepare and calibrate a model, there are always
factors which will limit the accuracy of the output. In preparation of this model the most
significant limitations identified that will affect the calibration accuracy are:
1. The assumption that water entitlements are taken as a constant rate for each
month. Historically the actual extraction from the river would be much more
variable than this and possess too many levels of complexity to be accurately
represented in a model.
2. The current quantity of water extracted from the catchment is unknown. Although
DPIW have provided water licence information (WIMS Dec 2006) and estimates of
extractions in excess of these licences, these may not represent the true quantity of
water extracted. No comprehensive continuous water use data is currently
available.
3. The quality of the observed flow data (ratings and water level readings) used in the
calibration may not be reliable for all periods. Even for sites where reliable data
and ratings has been established the actual flow may still be significantly different
to the observed (recorded) data, due to the inherent difficulties in recording
accurate height data and rating it to flow. These errors typically increase in periods
of low and high flows.
4. Misrepresentation of the catchment precipitation. This is due to insufficient rainfall
gauge information in and around the catchment. Despite the Data DRILL’s good
coverage of grid locations, the development of this grid information would still rely
considerably on the availability of measured rainfall information in the region. This
would also be the case with the evaporation data, which will have a smaller impact
on the calibration.
5. Catchment freezing and snowmelt in the upper catchment, during the winter
months, may affect the flow regime and this has not been specifically handled
within this model.
6. The daily average timestep of the model may smooth out rainfall temporal patterns
and have an effect on the peak flows. For example, intense rainfall events falling in
a few hours will be represented as a daily average rainfall, accordingly reducing the
peak flow.
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7. The model does not explicitly account for changes in vegetation and terrain within
individual sub-cathments. Effects due to vegetation and terrain are accounted for
on catchment average basis, using the global AWBM fit parameters. Therefore
individual sub-catchment run-off may not be accurately represented by the model’s
global fit parameters. To account for this a much more detailed and complex model
would be required.
8. The simple operating rules and assumptions used to model the catchment
modification (Lake Isandula) cannot capture the complexities of operation that
occur in reality
4.4.2 Model Accuracy - Model Fit Statistics
The following section is an additional assessment of how reliably the model predicts
flow at the calibration site.
One of the most common measures of comparison between two sets of data is the
coefficient of determination (R2). If two data sets are defined as x and y, R2 is the
variance in y attributable to the variance in x. A high R2 value indicates that x and y
vary together – that is, the two data sets have a good correlation. In this case x and y
are observed flow and modelled calibration flow. So for the catchment model, R2
indicates how much the modelled calibration flow changes as observed flow changes.
Table 4.6 shows the R2 values between observed and modelled daily and monthly
flows, as well as the proportional difference (%) between the long-term observed and
modelled calibration flows.
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Table 4.6 Model Fit Statistics
Measure of Fit Leven River at
Bannon’s Bridge
(Site 14207)
Gawler River at
West Gawler
(Site 14208)4
Daily coefficient of determination (R2 Value)
0.69 0.75
Monthly coefficient of determination (R2 Value)
0.95 0.92
Difference in observed and estimated long term annual average flow
+0.0% -0.2%
As previously mentioned the focus of the calibration process was to obtain a good
correlation between monthly long term volumes (and flows) and lesser priority was
given to daily correlations. However without a good simulation of daily flows, a good
simulation of monthly flows would be difficult to achieve. A target R2 of 0.70 (or
greater) was set for the daily flows and a target of R2 of 0.85 (or greater) was set for
monthly flows. It was deemed that these were acceptable targets considering the
model limitations and potential sources of error (refer to 4.4.1). A summary of
comparative qualitative and statistical fit descriptions are provided in the following
Table.
Table 4.7 R2 Fit Description
Qualitative Fit Description Daily R2 Monthly R2
Poor R2 < 0.65 R2 < 0.8
Fair 0.65 ≥ R2 > 0.70 0.8 ≥ R2 > 0.85
Good R2 ≥ 0.70 R2 ≥ 0.85
It should be noted that although the R2 value is a good indicator of correlation fit it was
only used as a tool, to assist in visually fitting the hydrographs. One of the major
4 The calibration fit for the Gawler River will be influenced by the basic modelling of the operation of Lake Isandula
(refer to section 4.2).
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limitations is that minor differences in the timing of hydrograph events can significantly
affect the R2 value, although in practice a good calibration has been achieved.
Another indicator on the reliability of the calibration fit is the proportional difference
between observed data and the modelled calibration flow (MCF), measured by percent
(%). The proportional difference for the daily flows and monthly volumes were
calculated and are presented in Figure 4-14 to Figure 4-17 in the form of a duration
curve. These graphs show the percentage of time that a value is less than a specified
bound. For example in Figure 4-14, 40% of the time the difference between the MCF
and observed flow is less than 23%. Similarly in Figure 4-15, for the All of Record
trace, 50% of the time the difference between the MCF monthly volume and observed
volume is less than 17%.
0
10
20
30
40
50
60
70
80
90
100
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percentage of time Difference is less than
Difference (%) - Observed vs Modelled
All record Winter Summer
Figure 4-14 Duration Curve – Daily flow percentage difference – Leven River
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0
10
20
30
40
50
60
70
80
90
100
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percentage of time Difference is less than
Difference (%) - Observed vs Modelled
All record Winter Summer
Figure 4-15 Duration Curve–Monthly volume percentage difference – Leven River
0
10
20
30
40
50
60
70
80
90
100
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percentage of time Difference is less than
Difference (%) - Observed vs Modelled
All record Winter Summer
Figure 4-16 Duration Curve – Daily flow percentage difference – Gawler River
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0
10
20
30
40
50
60
70
80
90
100
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percentage of time Difference is less than
Difference (%) - Observed vs Modelled
All record Winter Summer
Figure 4-17 Duration Curve –Monthly volume percentage difference-Gawler River
Although these duration curves are an indicator of the reliability of the modelled data,
they also have their limitations and should be used in conjunction with a visual
assessment of the hydrograph fit in determining calibration reliability. One of the major
limitations is that in periods of low flow, the percentage difference between observed
and modelled can be large although the value is not significant. For example, a
1ML/day difference, would show as a 200% difference if the observed flow was 0.5
ML/day. The duration curve graphs shows three traces, the Summer5, the Winter6 and
All of Record. The higher values, caused by the larger proportion of low flows, can be
clearly seen in the Summer trace.
4.4.3 Model accuracy across the catchment
The model has been calibrated to provide a good simulation for monthly and seasonal
volumes at the calibration site. Calibration sites are typically selected low in the
catchment to represent as much of the catchment as possible. How the reliability of
this calibration translates to other specific locations within the catchment is difficult to
5 Summer period = Nov to April.
6 Winter period = May to Oct.
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accurately assess, however on average it would be expected that the model calibration
would translate well to other locations within the catchment. The accuracy of the model
in predicting monthly volumes at other locations has been analysed for five river
catchments modelled as part of this project. The results of this assessment are
summarised in Appendix A. These analyses suggest that on average the models
predict volumes well across the catchment.
The fit of the hydrograph shape (daily flows) is expected to be more site specific and
therefore it is predicted that the calibration fit of these will deteriorate as the catchment
area decreases.
In the Leven and Gawler catchment there are two gauging sites which can be used to
assess the calibration fit at alternative locations. Plots of the monthly time series
volumes and the corresponding R2 values are shown in Figure 4-18 and Figure 4-19.
The results show that the correlation between modelled and observed volumes at
these two sites compares favourably with that of the calibration site. Comparison of
site 14227 gives a poorer fit during the winter periods (high flows), however a brief
check of associated flow ratings shows that there is only one high stage gauging and
multiple rating curves so the poorer fit may be due to poor high stage ratings at this
site.
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
1983 1984 1987 1989 1991 1993
Monthly Volume (ML)
Observed - Leven at Mayday Rd - Site 821SC6 Modelled - with entitlements extracted (Scenario 2)
R2 = 0.92
Figure 4-18 Time Series of Monthly Volumes- Site 821
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0
1000
2000
3000
4000
5000
6000
06/1987 05/1988 05/1989 05/1990 06/1991 05/1992 05/1993 05/1994
Monthly Volume (ML)
Observed - West Gawler u/s Isandula Res - Site 14227
SC5 Modelled - with entitlements extracted (Scenario 2)
R2= 0.92
Figure 4-19 Time Series of Monthly Volumes- Site 14227
4.5 Model results
The completed model and user interface allows data for three catchment demand
scenarios to be generated;
• Scenario 1 – No entitlements (Natural Flow)
• Scenario 2 – with Entitlements (with water entitlements extracted)
• Scenario 3 - Environmental Flows and Entitlements (Water entitlements
extracted, however low priority entitlements are limited by an environmental
flow threshold).
For each of the three scenarios, daily flow sequence, daily flow duration curves, and
indices of hydrological disturbance can be produced at any sub-catchment location.
For information on the use of the user interface refer to the Operating Manual for the
NAP Region Hydrological Models (Hydro Tasmania 2004).
Outputs of daily flow duration curves and indices of hydrological disturbance at the model
calibration sites are presented below and in the following section. The outputs are a
comparison of scenario 1 (No entitlements - Natural) and scenario 3 (environmental
flows and entitlements) for period 01/01/1900 to 01/01/2007. Results have been
produced at two locations:
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• Site 14207- Leven Rivar at Bannon’s Bridge at sub-catchment 4.
• Site 14208- Gawler River at West Gawler at sub-catchment 3.
0.10
1.00
10.00
100.00
1000.00
10000.00
100000.00
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percent Of Time Exceeded
Flow (ML/d)
Scenario1 (Natural)
Entitlements Extracted
Figure 4-20 Daily Duration Curve – Leven River
0.10
1.00
10.00
100.00
1000.00
10000.00
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percent Of Time Exceeded
Flow (ML/d)
Scenario1 (Natural)
Entitlements Extracted
Figure 4-21 Daily Duration Curve – Gawler River
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4.5.1 Indices of hydrological disturbance
The calculation of the estimates of natural flows and current flows (farm dams and
irrigation) were used to calculate indices of hydrological disturbance. These indices
include:
• Index of Mean Annual Flow
• Index of Flow Duration Curve Difference
• Index of Seasonal Amplitude
• Index of Seasonal Periodicity
• Hydrological Disturbance Index
The indices were calculated using the formulas stated in the Natural Resource
Management (NRM) Monitoring and Evaluation Framework developed by SKM for the
Murray-Darling Basin (MDBC 08/04).
The following table shows the Hydrological Disturbance Indices at 6 locations within the
catchment, comparing scenario 1 (No entitlements - Natural) and scenario 3
(environmental flows and entitlements) for period 01/01/1900 to 01/01/2007. Four sites
in addition to the calibration sites have been selected to give an indication of the
variability of the indices of hydrological disturbance across the catchment.
Table 4.8 Hydrological Disturbance Indices
Disturbance Indices
Values
undisturbed (natural flow)
SC4
Leven River site 14207
SC9
Leven River
SC10
Leven River
SC3
Gawler River site 14208
SC8
Gawler River
SC23
Gawler River
Index of Mean Annual Flow, A 1.00 0.99 0.99 1.00 0.91 0.97 0.98
Index of Flow Duration Curve Difference, M 1.00 0.94 0.97 1.00 0.60 0.79 0.80
Index of Seasonal Amplitude, SA 1.00 0.95 0.97 1.00 0.80 0.93 0.94
Index of Seasonal Periodicity, SP 1.00 1.00 1.00 1.00 1.00 1.00 1.00
Hydrological Disturbance Index, HDI 1.00 0.96 0.98 1.00 0.77 0.89 0.90
Hydrological Disturbance Index: This provides an indication of the hydrological
disturbance to the river’s natural flow regime. A value of 1 represents no hydrological
disturbance, while a value approaching 0 represents extreme hydrological disturbance.
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Leven & Gawler Surface Water Model Hydro Tasmania Version No: 2.1
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Index of Mean Annual Flow: This provides a measure of the difference in total flow
volume between current and natural conditions. It is calculated as the ratio of the current
and natural mean annual flow volumes and assumes that increases and reductions in
mean annual flow have equivalent impacts on habitat condition.
Index of Flow Duration Curve Difference: The difference from 1 of the proportional
flow deviation. Annual flow duration curves are derived from monthly data, with the index
being calculated over 100 percentile points. A measure of the overall difference between
current and natural monthly flow duration curves. All flow diverted would give a score of
0.
Index of Seasonal Amplitude: This index compares the difference in magnitude
between the yearly high and low flow events under current and natural conditions. It is
defined as the average of two current to natural ratios. Firstly, that of the highest monthly
flows, and secondly, that of the lowest monthly flows based on calendar month means.
Index of Seasonal Periodicity: This is a measure of the shift in the maximum flow
month and the minimum flow month between natural and current conditions. The
numerical value of the month with the highest mean monthly flow and the numerical
value of the month with the lowest mean monthly flow are calculated for both current and
natural conditions. Then the absolute difference between the maximum flow months and
the minimum flow months are calculated. The sum of these two values is then divided by
the number of months in a year to get a percentage of a year. This percentage is then
subtracted from 1 to give a value range between 0 and 1. For example a shift of 12
months would have an index of zero, a shift of 6 months would have an index of 0.5 and
no shift would have an index of 1.
4.6 Flood frequency analysis
A flood frequency plot has been developed at both the Leven at Bannon’s Bridge (site
14207) and Gawler at West Gawler (site 14208) gauging sites. The plot shown below
in Figure 4-22 and Figure 4-23 consists of three traces:
1. Observed
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