LOWER
PARRAMATTA RIVER
FLOOD STUDY
MARCH 2012
The following document entitled 'Lower Parramatta River Flood Study', which was prepared for the NSW Public Works Department in 1986, contains important historical and reference information regarding flooding in the Parramatta River and Powells Creek catchments.
It is published with permission.
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U Wo rks Department
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62"1. 4 0 0/,r y^ LOW R PARR AM AT:TA RIVER FLOOD STUDY
FEBRUARY 1986
R.J. EAGLE M.G. GEARY Chief Engineer Principal Engineer Public Works Department Rivers and Ports Branch
REPORT No PWD 84017
PREPARED BY WILLING & PARTNERS PTY LTD. FOREWORD
LOWER PARRAMATTA RIVER FLOOD STUDY
The Government's Flood Policy is directed towards providing solutions to existing flood problems in developed areas and ensuring that new development is compatible with the flood hazard and does not create additional flooding problems in other areas.
The management of flood liable lands rests with local councils, and it is envisaged that, in applying the policy, councils will formulate and implement floodplain management plans.
Such plans require the consideration and integration of complex engineering and planning factors and to assist councils in this regard the State Government provides specialist technical advice.
The advice may be provided directly by way of flood studies or indirectly by the participation of Government Departments in floodplain management studies or floodplain management committees co-ordinated by council.
The Lower Parramatta River Flood Study provides the Councils of Parramatta, Auburn, Ryde and Concord with information on the nature and extent of flood hazard along the lower reaches of the river and its tributaries.
This study represents the first phase of the development of appropriate management plans for the river and will enable the respective councils to assess the need for specific floodplain management studies prior to the adoption and implementation of floodplain management plans. TABLE OF CONTENTS
Section Page
FOREWORD
1.0 SUMMARY 1
2.0 INTRODUCTION 4
3.0 THE STUDY AREA
3.1 General 5 3.2 Rivers and Main Tributaries 5 3.3 Urbanisation 7 3.4 Existing Hydraulic Features 7 3.5 Lennox Bridge 8
4.0 DATA SOURCES
4.1 Plans and Surveys 9 4.2 Survey Datum 9 4.3 Rainfall 9 4.4 Flow Gauging Stations 10 4.5 Tides 10 4.6 Previous Studies 11
5.0 HISTORICAL FLOOD RECORDS
5.1 General 13 5.2 Commonwealth Government 13 5.3 State Government 13 5.4 Local Government 14 5.5 Libraries and Newspapers 14 5.6 Personal Interviews 15 5.7 Summary of Results of Historical Search 15
6.0 FLOOD ESTIMATES
6.1 General 18 6.2 Estimates Based on Historical Data at Lennox Bridge - 1984 18 6.3 Estimates Based on Australian Empirical Methods 22 6.4 Estimates Based on the Synthetic Unit Hydrograph Method - 1984 22 6.5 Estimates Based on the Regional Stormwater Model (RSWM - 1984) 23 6.6 Previous Flood Estimates 27 6.7 Design Floods 28 6.8 Effect of Retarding Basin Proposals 31
(i) Section Page
7.0 ESTIMATED FLOOD PROFILES
7.1 Introduction 33 7.2 Steady State Flow Model 33 7.3 Unsteady State Flow Model 33 7.4 Tidal Influences 34 7.5 Lower Parramatta River 35 7.6 Duck River 36 7.7 Haslams Creek and Powells Creek 38 7.8 Flow Distribution 39
8.0 ACKNOWLEDGEMENTS 40
9.0 REFERENCES 41
APPENDIX A PLANS AND SURVEY DATA A.I. List of Plans and Drawings A.2 List of Bench Marks
APPENDIX B DAILY RAINFALLS IN EXCESS"OF 100 mm
APPENDIX C FLOOD INFORMATION C .1 List of Organisations Approached for Historical Flood Level Information C .2 Council Interviews C .3 Flood Reports C.4 Personal Interviews C.5 Recorded Flood Levels
APPENDIX D FLOOD ESTIMATES DATA D.I. Rational Method Flood Estimates for Parramatta River - 1984 D.2 RSWM Subcatchment Details and Adopted Parameter Values - 1984
APPENDIX E UNSTEADY STATE FLOW MODEL, USTFLO E.1 Program Description E.2 Model Testing - Lower Parramatta River
(ii) LIST OF TABLES
5.1 Summary of Historical Floods Identified 16 6.1 Daily Rainfall Records 1889, 1914 Storms 20 6.2 Analysis of Observed Floods at Lennox Bridge 21 6.3 Synthetic Unit Hydrograph Flood Estimates - 1984 23 6.4 Results of Calibration and Verification of RSWM - 1984 26 6.5 RSWM Flood Estimates with Synthetic Storms - 1984 27 6.6 Flood Estimates at Charles Street Weir - 1976 27 6.7 Flood Estimates at Lennox Bridge - 1980 28 6.8 Comparison of Flood Estimates 29 6.9 Adopted Peak Design Flows 31
LIST OF PLATES
1. 1961 Flood at Lennox Bridge 17 2. 1961 Flood downstream of Lennox Bridge 17
LIST OF EXHIBITS
1. Locality and Urbanisation Maps 2. Catchment Map 3. Location of Surveyed River Cross-Sections 4, Relationship Between Survey Datums 5. Rainfall Records 6. Locations of Rainfall Stations 7. Rainfall Frequency Curves. Parramatta 8. Positions of Observed Flood Levels .9. Flood Profiles at Lennox Bridge 10. Rating Curves for Lennox Bridge 11. Comparison of Flood Frequency Curves 12. Catchment Map showing Storm Isohyets, 9-10 Feb 1956 13. Catchment Map showing Storm Isohyets, 19 Nov 1961 14. Pluviograph Records March 1967 and June 1975 15. Diagrammatic Representation of the RSWM 16. Representation of Links in the RSWM 17. Catchment Map with Isochrones 18. Adopted Peak Design Flows 19. Tide Data for Lower Parramatta River 20. Lower Parramatta River Trial Flood Profiles 21-1 Lower Parramatta River 1%, 2% and 5% Flood Profiles CH 1000 - 6100 21-2 Lower Parramatta River 1%, 2% and 5% Flood Profiles CH 6100 - 10180 22. Duck River, Haslams Creek and Powells Creek 1%, 2% and 5% Flood Profiles 23. Lower Parramatta River and Tributaries Plan of 1%, 2% and 5% Design Flood Levels 24. Lower Parramatta River and Tributaries 1% Flood Distribution 25. Lower Parramatta River and Tributaries 2% Flood Distribution 26. Lower Parramatta River and Tributaries 5% Flood Distribution
(iii) 1.0 SUMMARY
Flood levels and discharge distributions have been computed for the 1%, 2% and 5% probability floods for the Lower Parramatta River from Charles Street Weir to Ryde Bridge and for Duck River, Haslams Creek and Powells Creek to Mona Street, the Western Freeway and Pomeroy Street respectively. The study area is shown on Exhibit 1 (a) and the study limit for determination of flood information is shown on Exhibit 23.
A search of historical data was undertaken, including previous studies, governmental records, libraries, newspapers, personal interviews and field inspections in order to determine the dates and extent of the most significant floods. Information collected included rainfall records, flood reports, historical developments, previous studies, survey and mapping.
The historical search indicated that the Lower Parramatta River experienced significant floods in 1889, 1914, 1956, 1961, 1967 and 1975. The largest of these occurred in 1889 and 1914 when the catchment was relatively undeveloped.
Data on historical floods is generally limited. Only Parramatta City Council, the MWS&DB and the Water Resources Commission maintain systematic records of flooding in the catchment, and most of this is limited to recent decades. It should be noted that there has not been major flooding along the river in recent years.
Several previous studies have been conducted into the Upper Parramatta River. These include two major studies performed by the Consultant and others in 1976 and 1980. The 1976 Report was commissioned to investigate flood mitigation options for the Upper Parramatta River catchment above Charles Street Weir. The 1980 Report was commissioned to investigate in detail three of the flood mitigation options and presented the results of physical hydraulic model testing for Lennox Bridge, which is approximately 500 m upstream of the study limit for this investigation.
Establishment of a rating curve from the model tests for Lennox Bridge in 1980 and the availability of recorded peak flood levels in the vicinity of Lennox Bridge enabled peak discharges to be estimated for the six major historical floods. Records of the rainfall which produced those floods were also available.
However, the historical flood level data and discharge estimates are not sufficiently detailed and. complete to enable flood level probabilities to be defined by historical- events alone. In addition the flood level data is non-homogeneous because of increasing urbanisation and its effects on flood runoff.
1 Accordingly estimates of the 1%, 2% and 5% probability floods were made using a total of four different hydrological methods: the Rational method, the Cordery-Webb method, independent study by Fitzgerald and the Regional Stormwater Model (RSWM). After initial comparison of the results from these methods with the historical floods, the RSWM was subject to further verification against the estimated historical discharges to confirm its suitability and was selected as the most applicable method for estimating the 1%, 2% and 5% probability peak discharges. Using the RSWM also enabled relevant catchment features to be modelled and discharge hydrographs to be obtained as required throughout the catchment.
Synthetic rainfall data for the 1%, 2% and 5% storms was adopted from previously derived rainfall intensity-frequency- duration curves for Parramatta (Reference 2).
The critical storm duration for the Lower Parramatta River is`-) generally different to the critical storm duration for its tributaries. Therefore major flooding of the tributaries may not coincide with major flooding on the Lower Parramatta River. It was concluded that:
- major flooding on the tributaries would be most likely to result from localised storms,
major flooding in the Lower Parramatta River, as indicated by historical flood data, would result from long duration heavy rainfall generally over the entire catchment area.
Hydraulic analyses were undertaken for the Lower Parramatta River and its tributaries, Duck River, Haslams Creek and Powells Creek.
Survey for use in the hydraulic models was based on hydrographic survey of 10 km of portions of the Lower Parramatta River undertaken in 1926, 1938, 1977, 1978 and 1979, checked against further survey of seven sections by the PWD in 1983. Limited overbank survey was performed by the Consultant. Cross-sectional survey of Duck Creek (11 locations), Haslams Creek (5 locations) and Powells Creek (7 locations) was performed by the PWD in 1983.
The Lower Parramatta River was initially analysed using both steady and unsteady flow hydraulic models. The unsteady flow model is more representative of the actual physical river system since it enables floodplain storage and tidal effects to be taken into account. However, the steady state model, being simpler in application, was also established to test the sensitivity of flow and roughness parameters, and to assess the applicability of the steady state model for final design runs. The two models were in good agreement in the reach below Charles Street; however, significant differences in computed flood levels did occur in the lower reaches where storage effects became important. Comparison with the limited historical data indicated that use of the unsteady state flow model would be necessary for final design runs.
2 Accordingly the unsteady flow model was adopted for determining design flood levels on the Lower Parramatta River.
Duck River, Haslams Creek and Powells Creek, where storage effects were of less importance, were analysed using a steady state flow model. The model parameter values for Duck River were determined based on the limited historical data. The analyses for the other two creeks were based on assessed model parameter values in the absence of historical data.
The design flood levels for the Lower Parramatta River, Duck River, Haslams Creek and Powells Creek, derived using the hydraulic model, are presented for the 1%, 2% and 5% probability floods as:
Exhibit 21-1: Lower Parramatta River flood profile showing design flood levels CH 1000-6100,
Exhibit 21-2: Lower Parramatta River flood profile showing design flood levels CH 6100-10180,
Exhibit 22 : Duck River, Haslams Creek and Powells Creek flood profiles showing design flood levels.
Exhibit 23 : Plan of all watercourses showing design flood levels,
Exhibit 24 : Plan of all watercourses showing the 1% flood distribution and velocities.
Exhibit 25 : Plan of all watercourses showing the 2% flood distribution and velocities.
Exhibit 26 : Plan of all watercourses showing the 5% flood distribution and velocities.
3 2.0 INTRODUCTION
The first stage of the Government's Flood Policy involves the determination of the nature and extent of the flood problem through a Flood Study.
The aim of this study was to determine the 1%, 2% and 5% probability flood levels and discharge distributions along the Lower Parramatta River and major tributaries. The catchment area is shown on Exhibit 1 (a) and the limits for determining flood information are shown on Exhibit 23.
The principal requirements of the study included:
(a) the collection, collation and analysis of historical flood data;
(b) hydrologic catchment modelling to estimate flood peaks and discharge hydrographs; and
(c) determination of the 1%, 2% and 5% probability flood levels and discharge information for existing conditions.
The upstream extremity for the study was the limit of tidal influence which is the weir at Charles Street. The downstream limit of the study was Ryde Bridge, where storm tides become the dominant factor in determining flood levels. Sections of Duck River, Haslams Creek and Powells Creek were also studied, with the total length of watercourses involved being in excess of 20 kilometres.
4 3.0 THE STUDY AREA
3.1 General
The study area, shown on Exhibit 1, comprised the catchments of the Parramatta River and its tributaries between the Ryde Bridge at Uhrs Point and Charles Street Weir. The area includes sections of the western and north-western suburbs of Sydney. The major urban centre of Parramatta is located on both sides of Parramatta River immediately upstream of the study area. The study area was also taken to include the âarramatta River catchment upstream of Charles Street Weir for the purposes of flood estimation.
The total catchment area upstream of Ryde Bridge is 212 sq. km. The principal watercourses include Toongabbie Creek and Darling Mills Creek, which join 3 km upstream of Parramatta to form the Parramatta River. Downstream of Parramatta the major tributary is Duck River. In the south-east, Haslams Creek and Powells Creek drain into Homebush Bay which is a tidal arm of the Parramatta River.
Catchment conditions range from hilly areas with steep-sided gullies in the northern parts, to mangrove flats beside the lower reaches of Parramatta River. The highest areas of the catchment are at RL 180 m (AHD) but most of the catchment varies between RL 10 m and RL 50 in.
The study area was divided into nine subcatchments, as shown on Exhibit 2, for the purpose of analysis. These subcatchments corresponded to the main tributaries of the river. Details of the subcatchments are given in Appendix D.
Although the catchment is not completely urbanised it is one of the largest urban catchments existing in Australia. Since development of the upper catchment is increasing, it can be expected that future flood producing storms will cause higher flood levels than those observed for similar storms in the past.
The mean annual rainfall varies significantly over the catchment. At Prospect Reservoir in the south-west (78 years record) it is 864 mm, but in the north-east it rises to 1206 mm at Observatory. Hill, Sydney (79 years record). At Cumberland Forest (25 y^ars record) the mean annual rainfall is 1200 mm. Flood producing storms have been recorded at all times of the year and show no significant seasonal trend. Historical floods have resulted from major storms over the Sydney region with daily rainfalls of 100 mm to 300 mm. These flood producing storms have sometimes persisted for up to five days.
3.2 Rivers and Main Tributaries
There are nine subcatchments with associated watercourses in the study area as shown on Exhibit 2. The watercourses include the tide affected river, steep natural creeks and man-made lined concrete channels. The following sections
5 describe the eight major watercourses relevant to the Lower Parramatta River.
(a) Lower Parramatta River
The focus of this study is the tide affected section of the Parramatta River between Ryde Bridge and Charl,es__$treet_Weir, at Parramatta . The weir acts as a tidal barrier limiting the length_. of the tide affected reach to approximately 9.2 km., Most of this reach is considered to be a drowned river valley] forming an arm of Port Jackson. Its width varies from about 300 m at Ryde Bridge to less than 50 m at Charles Street Weir. The catchment areas at these two points are 212 sq. km' and 108 sq . km respectively . The mean tidal range in this reach is approximately 1.0 m.
(b) Upper Parramatta River
Upstream from Charles Street Weir, the Parramatta River extends as a well defined partially modified river to the junction of Toongabbie Creek and Darling Mills Creek. This river reach is approximately 2.5 km long and contains within this section several weirs and the historic Lennox Bridge.
(c) Toongabbie Creek
Toongabbie Creek and its tributaries drain urban areas between Westmead and Blacktown . The total catchment area of 70 sq, km has been developed largely since 1956. Prior to 1950 most of the catchment was used for farming, and some farms still remain in the Prospect area. A number of the creeks have been channelised.
(d) Darling Mills Creek
Development of Darling Mills Creek is limited to the edges of the catchment and the main creeks ( Hunts Creek and Darling Mills Creek ) are in a nearly natural condition . Large areas of bushland and forest remain, including the Cumberland State Forest. The catchment has an area of approximately 30 sq. km and experiences higher average rainfalls than elsewhere in the study area.
(e) Vineyard Creek and Subiaco Creek
Vineyard Creek and Subiaco Creek drain undulating to hilly terrain between Rydalmere and Eastwood . The creeks are narrow and relatively steep. Localised flooding has been reported along both creeks.
(f) Duck River
Duck River and its tributaries , A'Becketts Creek and Duck Creek, drain densely urbanised land between Granville and Yagoona. The flat terrain attracted early development. There is little open space in the catchment except for a strip of parkland along Duck River.
6 (g) Haslams Creek and Powells Creek
These two creeks drain urban areas extending from Lidcombe to Strathfield, south of Parramatta Road. The part of the catchment north of Parramatta Road is mostly flat and undeveloped. Both creeks flow into Homebush Bay.
3.3 Urbanisation
Parramatta is the second oldest European settlement in Australia, having been established in 1788 as a farming centre. In the early 1800s it had a larger population than Sydney itself and in the 19th century settlement gradually increased in the eastern half of the study area between Parramatta and Sydney.
The rapid expansion in catchment urbanisation west of Parramatta occurred within the last 30 years. This is apparent from Exhibit 1(b) which indicates the areas urbanised in the Upper Parramatta River catchment at various times since the last century. The figure has been compiled from various sources including old maps and aerial photographs.
3.4 Hydraulic Features
The locations of existing hydraulic features are shown on Exhibit 2 and include:
(a) Lake Parramatta
The dam forming Lake Parramatta was constructed as a town water supply in 1857 and was increased to 13 m in height in 1898. The dam now provides a recreational facility surrounded by bushland.
The dam has a spillway approximately 100 m in length. No significant routing effect would result during the passage of floods through the reservoir because the spillway crest length is relatively long compared to the storage area and flood flows would pass directly through.
(b) Charles Street Weir
Charles Street Weir separates the tidal section of the Parramatta River from the non-tidal section. The weir is a concrete structure with a curved crest, 80 m in length and a height of 2 m. It backs up the water in the Parramatta River to the Marsden Street Weir.
7 (c) Marsden Street Weir
This weir, which is situated upstream of the Marsden Street Bridge, was constructed in 1818 for town water supply purposes. It is a stone wall 80 m long and 3.7 m high. The weir creates a lake with the backwater reaching approximately 1.3 km upstream of the weir.
(d) Parramatta Park - Weir 1
This weir is a low-level crossing for vehicles. It is of concrete construction, curved in plan, 45 m long and 2 m high. It causes little backup of water in the river.
(e) Parramatta Park - Weir 2
This weir is a more substantial structure than Weir 1. It was built from local sandstone blocks in 1831 and was also a water supply source for Parramatta. The height of the structure is 2.5 m and its length is 40 m. The ornamental pool behind the weir stretches back approximately 0.8 km along the. Parramatta River.
3.5 Lennox Bridge
Lennox Bridge is situated in the business district of Parramatta and carries Church Street over the Parramatta River. Lennox Bridge was built in 1839 and has been listed by the National Trust. The bridge is a single arch with less waterway area than comparable modern bridges . The effect of the bridge on floods is detailed in Section 6 .2 of this report.
8 4.0 DATA SOURCES
4.1 Plans and Surveys
All available maps, plans and reports of relevance have been obtained and used in this study. The list of drawings is presented in Appendix A.
Additional survey work was carried out by both the Consultant and the Public Works Department to determine river cross-sections, the locations of which are shown on Exhibit 3.
4.2 Survey Datum
The survey plans and other information referred to in Section 4.1 show levels on a variety of datums. Information on the location of bench marks was obtained from the MWS&DB, Lands Department, DMR, local Councils and the Australian Survey Office.
For consistency all levels in this report are expressed in metric units to Australian Height Datum (AHD). The relationship of the various datums 'is shown on Exhibit 4. Appendix A contains a list of bench marks used for survey within the catchment.
4.3 Rainfall
4.3.1 Historical Rainfall Records
Daily rainfall data for the full period of record from each of 39 daily rainfall stations, as shown on Exhibit 5, were obtained from the Bureau of Meteorology. This data was used to identify dates of high rainfall and hence the dates for which records of flooding may be available (Section 5). The daily rainfall information was also used to define the areal distribution of rainfall for major flood producing storms which were used in the hydrologic modelling studies described in Section 6.
Pluviograph records were obtained for several stations`in the study area and these were used to define the temporal pattern of rainfall in the modelling studies referred to above. The periods of record available from the pluviograph stations are also shown on Exhibit 5.
The locations of the daily rainfall and pluviograph stations used in this study are shown on Exhibit 6.
Potential flood producing' storms were identified by obtaining 5 the dates when daily rainfall exceeded 100 mm for rainfall stations at Parramatta, Lidcombe Golf Club and Ryde Pumping Station. The data used is presented in Appendix B.
9 4.3.2 Rainfall Intensity-Frequency-Duration Curves
The rainfall intensity-frequency-duration curves derived are shown on Exhibit 7. These IFD curves were previously derived by the Consultant for the Parramatta River catchment (Ref. 2). Comparison with more recent data (Ref. 3) showed negligible differences, hence the previous results were adopted.
4.3.3 Rainfall Temporal Patterns
Rainfall temporal patterns for historical storms were derived from records of the pluviograph stations presented on Exhibit 6. Temporal patterns for synthetic storms were derived from the patterns given in Reference 3 for Sydney.
4.4 Streamflow Gauging Stations
In 1979, two streamflow gauging stations (WRC Nos. 213004 and 213005) were established by the WRC upstream from Lennox Bridge. They are located on the Parramatta River at Parramatta Hospital upstream of Marsden Street Weir and on Toongabbie Creek upstream of Briens.Road bridge respectively. Their locations are shown on Exhibit 2.
Since 1979 only a few minor storms have occurred, the largest flow gauged to date being 83.0 m3/s on 21st March 1983, at station 213004.
4.5 Tides
Tide observations for Sydney Harbour (Port Jackson) are made by the MSB at Fort Denison, 14 km downstream of Ryde Bridge. All tidal observations are related to the zero of the Fort Denison tide gauge, at RL -0.925 m (AHD).
The mean tidal range is 1.07 m at Fort Denison and 1.12 m at Ryde Bridge. The highest recorded tides at Fort Denison were:
26 May 1880 1.505 m (AHD) 10 June 1956 1.435 m (AHD) 25 May 1974 1.445 m (AHD)
The MSB provided a frequency curve for high tides for the 30 year period from 1916 to 1945 at Fort Denison.
The PWD provided details of tidal current measurements carried out on 2nd February 1983. On this date, 4 days after a full moon, the predicted tidal range at Fort Denison was 1.5 m which is a high, but not extreme, Spring Tide. There was no significant inflow from the tributaries because the test date was preceded by a long dry period. Tidal elevations and velocity profiles were measured at three locations between Ryde Bridge and McArthur Street Bridge.
The effects of the tidal influences on flood levels is discussed in Section 7.4.
10 4.6 Previous Studies
4.6.1 1975 Preliminary Report
In 1975 the Snowy Mountains Engineering Corporation (SMEC) undertook a preliminary study of flooding and water quality problems in the non-tidal section of the Parramatta River catchment above the Charles Street Weir in Parramatta.
In the report (Ref. 4) it was recommended that a more detailed study be undertaken of flood problems which were being aggravated by increasing catchment urbanisation. Recommendations were also made for the collection of additional rainfall, runoff and water quality data.
4.6.2 1976 Report
The engineering investigations conducted for the 1976 report (Ref. 2) covered two possible drainage and flood mitigation schemes for the Parramatta River catchment. The first scheme investigated was a conventional stormwater drainage system consisting of concrete-lined channels at an estimated cost of approximately $22 million.
The second scheme proposed included up to 22 flood retarding basins. The estimated cost of this system was $11 million.
The 1976 Repor t recommended implementation of the basin system. This recommendation has been partially implemented at the present time.
4.6.3 1978 Report
In 1978 an inter-departmental committee, comprising the WRC, PWD, MWS&DB, and the Department of Local Government, was formed to examine flood mitigation requirements in the Parramatta River catchment. The Committee recommended (Ref. 5) that further and more comprehensive flood mitigation investigations should be carried out prior to adoption of the scheme proposed in the 1976 Report.
4.6.4 1980 Report
Towards the end of 1978, WRC became active in floodplain management in the Parramatta River catchment upstream of Charles Street Weir. This led to the commissioning of SMEC and Willing & Partners Pty Ltd as joint consultants to undertake a more detailed investigation of flood mitigation proposals.
The ensuing 1980 Report (Ref. 6) dealt primarily with four of the retarding basins proposed on Toongabbie Creek and Darling Mills Creek and flood problems in the central business area of Parramatta. The report also included a review of the previous recommendations for the remainder of the valley upstream of Charles Street Weir.
11 4.6.5 1981 Report
The April 1981 report by SMEC and Willing & Partners Pty Ltd (Ref. 7) dealt with design modifications to two retarding basins on Toongabbie Creek.
4.6.6 Subiaco Creek - Ponds Creek Drainage Study
This study was carried out for Parramatta City Council in 1980 by Willing & Partners Pty Ltd (Ref. 8). The study reviewed proposed retarding basin systems for the Subiaco Creek catchment, and recommended a system of up to six basins.
4.6.7 Haslams Creek Drainage Study
This study was- commissioned by Auburn Municipal Council (Ref. 9) and examined the flooding potential of the section of Haslams Creek downstream of Parramatta Road.
4.6.8 Pendle Hill Creek Trunk Drainage Study
A detailed investigation of a retarding basin on Pendle Hill Creek, a- tributary of Toongabbie Creek, was carried out for Holroyd Municipal Council (Ref. 10).
4.6.9 Greystanes Creek Trunk Drainage Study
This study carried out detailed investigation of five possible retarding basin sites on Greystanes Creek (Ref. 11).
12 5.0 HISTORICAL FLOOD RECORDS
5.1 General
The earliest recorded flood in the Parramatta River occurred in 1795. In the ensuing years, many other floods of varying severity have been recorded. Unfortunately, most of the records were of insufficient accuracy to enable the flood levels to be determined reliably. All relevant flood height records located are listed in Appendix C and the locations at which the records were taken are shown on Exhibit 8.
Information was sought for flood levels on the Lower Parramatta River and on the major tributaries of Vineyard and Subiaco Creeks to the north and the Duck River, Haslams Creek and Powells Creek to the south. Sources approached for information included Commonwealth and State Government Departments, - State and Local Government Authorities, metropolitan and local newspapers, libraries and historical societies. The departments, authorities and other organisations approached are listed in Appendix C. Furthermore, personal interviews were conducted with residents and business proprietors of properties near the Parramatta River and its tributaries.
Where information was available, the historical flood levels were surveyed and reduced to AHD,
5.2 Commonwealth Government
Newington Armaments Depot, owned by the Department of Defence, has a river frontage on the south bank of the Parramatta River extending over 1.2 km downstream from Jamieson Street. Much of this frontage is mangrove swamp. There are no records of flooding or flood heights at this location.
The officers at the Department of Defence Naval Stores at Rydalmere, on the north side of the river between Silverwater Road and Spurway Street, were able to give a good recollection of flood heights. These were most likely to have been observed during the 1974 flood. The floodwaters covered the concrete floor of Stores No. 4 and 5 to a depth of 100 mm. The average floor height is RL 1.40 AHD. The adopted flood level is RL 1.50 (Flood level No. 30 in Appendix B-2 and Exhibit 8).
Tide affected flooding is significant at this site, with regular minor overtopping of the banks during high spring tides.
5.3 State Government
5.3.1 Water Resources Commission
In 1979 the Water Resources Commission established stream gauging stations in the study area on Toongabbie Creek and
13 the Parramatta River (Section 4.4). No significant floods have occurred since these stations were installed.
5.3.2 State Rail Authority
The flood of May 1889 inundated the railway bridge over Duck River approximately 3.5 km upstream of the confluence with the Parramatta River. Reports made in 1889 indicated that the bridge which was submerged had a waterway opening approximately 8 metres wide, while the present structure, dating back to at least 1905, is over 18 metres wide. This suggests that the values for the high water levels given for the 1889 flood are of little relevance to the present situation.
Site observations confirm that the existing bridge structure has been substantially altered a number of times in the past. Examination of SRA files revealed no references to flooding in any of the areas covered by this report.
5.3.3 Metropolitan Water, Sewerage and Drainage Board
A considerable number of flood records were obtained from the Board for the period from May 1943 to July 1975. This included internal reports , correspondence , levels and photographs . Much of the information related to the severe localised storm on 25th April, 1974, in the Merrylands - Granville region, all outside the study area.
The Board ' s reports indicate that most of the flooding in the study area could be described as "local nuisance flooding" generally caused by constrictions and blockage of waterways or inadequately sized drainage channels and culverts.
5.4 Local Government
The area under consideration comes under the control of four Local Government bodies, those of Auburn Municipal Council, Concord Municipal Council, Parramatta City Council and Ryde Municipal Council. These councils were supplied with a list of dates when heavy rainfall occurred and flooding may have resulted. Parramatta City Council was the only Council which maintained detailed flood records and a total of 29 levels was obtained. Summaries of Council interviews are presented in Appendix C.
5.5 Libraries and Newspapers
The main sources of old newspaper files were the State Library of NSW and the Mitchell Library. The libraries at Parramatta and Ermington were also investigated but held no relevant information that was not available in the State Library.. The Parramatta Historical Society was approached but no'records of value in assessing historical flood levels were located. The Cumberland Press made their library available for research but again no useful flood information was located. Newspaper reports accounted for three flood levels of poor to fair accuracy as the information is
14 generally non-specific.
A summary of the relevant reports located is presented in Appendix C.
5.6 Personal Interviews
Personal interviews were conducted with people living or working near the Parramatta River and its main tributaries in order to obtain additional information on historical floods. Only seven interviewees provided useful and factual information. However, personal interviews (data accuracy: 6 poor, 1 fair) were the least reliable source of flood level information.
A summary of the information obtained from the interviews is in Appendix C.
5.7 Summary of Results of Historical Search
All flood level reports are assigned a reference number and appear in Appendix C and on Exhibit 8. The more recent floods of 1956, 1967, 1969, 1974 and 1975 provided the best flood level information.
The flood levels recorded at Lennox Bridge (outside the study area) for the 1889, 1914, 1956, 1961 and 1967 floods are useful because a rating curve (Ref. 6) has been established for the bridge and thus flows could be estimated for those floods.
A summary of reported floods is presented in Table 5.1.
15 TABLE 5.1
SUMMARY OF HISTORICAL FLOODS IDENTIFIED
Date of No. of Flood Flood Damage Levels Obtained
1795 - Bridge (in Parramatta) washed away - 1806 - Heavy storms reported - 1809 - Heavy storms reported - 1826 - Bridge damaged - June 1864 - Bridge washed away - 27th May 1889 - Substantial damage occurred 1 21st March 1914 = Widespread flooding and damages 1 7th July 1931 - Intense storms but no damage reported - 29th September 1943 - Intense rainfall. Little damage reported - February 1956 - Smith St. footbridge under 6 ft (1.83m) of water 5 November 1961 - Widespread damage reported 1 6th March 1967 - Minor flooding in northern tributaries 7 15th April 1969 - Parramatta River flooding 5 16th October 1972 - A'Becketts Creek local flooding 1 25th April 1974 - Severe thunderstorm, Granville area. Flooding of Duck River and tributaries 9 March 1975 - Heavy rain in coastal and southern suburbs. No flood damage reported in study area - 21st June 1975 - A storm produced rises in river levels but no flooding was reported. Some flood height observations were made by Parramatta City Council 4 4th March 1977 - High river levels, no flooding 1 20th March 1978 - High river levels, no flooding 1 2nd November 1981 - High river levels, no flooding 1
TOTAL 37
16 rLN:r 1961 Flood at Lennox Bridge
PLATE 2 1961 Flood downstream of Lennox Bridge
17 6.0 FLOOD ESTIMATES
6.1 General
The flood hydrology of the upper catchment above Charles Street Weir was investigated in earlier reports (Refs 2 & 6). The flood estimates prepared as part of this study extend the flood hydrology studies downstream from Charles Street Weir to Ryde Bridge. These new estimates incorporate some historical flood data which was not located during the earlier studies.
Despite the long history of flooding in the catchment, conventional flood frequency analysis of historical floods was not practicable because:
(a) flood level and flood discharge data for historical storms in this section of the river are deficient,
(b) the catchment has undergone a gradual transition from a natural to an urban condition hence making the limited available data non-homogeneous,
( c) flood heights may be influenced by tidal movements.
Because of these limitations : a number of appropriate alternative flood estimation techniques were used to estimate flows and the results compared . These methods were the rating curve at. Lennox Bridge in conjunction with recorded flood levels , an independent method developed for the ACT (Fitzgerald ), the Rational Method, the Cordery-Webb synthetic unit hydrograph method and the Consultant's Regional Stormwater Model ( RSWM ). In addition , estimates produced in previous studies using a range of analytical methods, were included for comparison purposes.
Sophisticated analytical methods cannot entirely overcome the difficulties and uncertainties created by poor or limited data. However , if the model can be calibrated to satisfactorily reproduce recorded events, it is considered acceptable.
6.2 Estimates Based on Historical Data at Lennox Bridge - 1984
6.2.1 Rating Curve
The probability of a flood may be estimated from observations taken at a fixed point on the river over a period of years. For accurate estimates of the 1% probability flood three criteria must be satisfied . These are:
(a) the annual maximum flood peak discharges in each year of record must be known with reasonable accuracy, (b) the sample period of record must be representative i.e. to estimate the 1% probability flood, more than 100 years of record should be available, and
18 (c) the record must be homogeneous, i.e. contain no physical changes such as catchment urbanisation or drainage modifications which affect the nature of the record with time.
None of these criteria is fully satisfied for the Parramatta River though the historical search produced flood level information recorded at Lennox Bridge over a long period. This data constituted the majority of the flood level data used in this study.
In the 1980 Report for Lennox Bridge a rating curve was presented from hydraulic model studies of the Parramatta River between Charles Street Weir and a point approximately 65 m upstream of Marsden Street Weir near the WRC stream gauging station (213004). Four flood profiles, for discharges of 125, 540, 791 and 1000 m3/s, were also derived during the model studies and these are shown on Exhibit 9. These profiles were used in the derivation of the rating curve for Lennox Bridge. This rating curve is affected by drawdown through Lennox Bridge; its location is shown on Exhibit 9. Accordingly, a new rating curve was prepared for a point just upstream of Lennox Bridge outTside the influence of the bridge drawdown effects. The location of the new curve is also shown on Exhibit 9. The new curve was derived by transposing the flood levels at the desired location from the four flood profiles plotted on Exhibit 9 to Exhibit 10; the resultant curve is designated (1).
The curve designated (2) on Exhibit 10 is also transposed from Exhibit 9. This curve is the tailwater curve and gives the flood levels immediately downstream of Lennox Bridge. The large difference between upstream and downstream flood levels is apparent from curves (1) and (2) and is greater than 3.5 metres for a flood of 1000 m3/s.
A third curve (3) is also shown on Exhibit 10. This curve was estimated from the sluice gate formula (Ref. 12). The sluice gate formula could not be expected to correspond to the derived rating curve (1) at low heads as the bridge opening would not act like a sluice until fully submerged. For flood levels greater than RL 9.5 the difference between the flood discharges by the two curves is less than 5% and the curves appear to converge. Hence, curve (3) increases the confidence in the reliability of the rating curves derived from hydraulic model studies for higher order floods with downstream submerged conditions.
6.2.2. Analysis of Observed Floods at Lennox Bridge
Available rainfall records were analysed so as to enable a probability of exceedance to be assigned to the five largest observed floods, which occurred, in order of decreasing flood level, in 1889, 1914, 1956, 1967 and 1961.
Rainfall values have been analysed rather than the estimated discharges since there has been a significant change in catchment conditions during the period of record. The
19 largest floods, 1889 and 1914, occurred when the catchment was relatively undeveloped. Should the flood producing rainfall of these storms be repeated today, the magnitude of the observed flood levels would exceed those originally observed.
Daily rainfalls for the 1889 and 1914 storms are shown in Table 6.1. No pluviograph data was available for these storms. Critical rainfall periods and temporal patterns were assumed on the basis of historical reports. For the 1956, 1961 and 1967 storms the flood producing rainfall was identified from the pluviograph records at Ryde.
TABLE 6.1
DAILY RAINFALL RECORDS ( mm) 1889, 1914 STORMS
Rainfall May 1889 March 1914 Station 26th 27th 28th 23rd 24th
Epping 108 115 294 - - Parramatta - - - 53 223 Prospect 80 89 314 47 117 West Pennant Hills - - - 56 245
Rainfall from the flood producing burst was assigned a probability based on the intensity-frequency-duration curve (Exhibit 7).
Additionally, the five highest observed flood levels at Lennox Bridge were plotted on the rating curve ( Exhibit 10) in order to estimate the peak discharge at the bridge during these floods.
The results of analysis of the observed floods are presented in Table 6.2 and they are plotted on Exhibit 11. The effect of increasing urbanisation is not distinguishable on the plotted curve due to the small sample size.
20 TABLE 6.2
ANALYSIS OF OBSERVED FLOODS AT LENNOX BRIDGE
Flood Rainfall Floods Dates
No. of Critical Critical Rainfall Observed Rated Stations Rainfall Storm Probab ' y Level Discharge Available Depth Duration (mm) (hours ) (%) ( m AHD ) ( m3/s) (1) (2) (3) (4) ( 5) (6)
1889 2 112 (7) 4 1%- 2% 7.9 790 1914 3 106 (8) 3 1%- 2% 7.3 710
1956 10 125 (9) 8 5%-10% 6.34 585 1967 3 80 (10) 5 10%-20% 6.10 550 1961 9 _ 92 (11) 3.5 5%-10% 5.8-6.3 510-580
Notes
(1) The total number of daily rainfall stations used to calculate the catchment average rainfall depths for the Parramatta River catchment above Charles Street Weir. (2) The rainfall depth for the most intense storm period obtained from pluviographs or assumed rainfall patterns which caused peak flood levels. (3) The duration of the rainfall in (2) which caused peak flood levels. (4) Derived from Exhibit 7 in conjuction with (2) and (3). (5) Actual recorded flood level at Lennox Bridge. (6) Estimated discharge derived from Lennox Bridge rating curve, Exhibit 10. Data from (4) and (6) has been plotted on Exhibit 11. (7) Daily rainfalls only are available. The maximum one day rainfall in the 3 day storm was 303 mm and a critical storm duration within this one day period was estimated using the temporal pattern in Ref. 3. This amounted to 112 mm or 37% of the one day total in 4 hours. (8) A critical storm period of 18 hours was adopted from historical reports and a temporal pattern assumed from Ref. 3. This resulted in 106 mm or 38% of critical rainfall depth in 3 hours. (9) Derived from Ryde pluviograph and rainfall isohyets (Exhibit 12). (10) Storm localised on upper catchment. Ryde pluviograph (Exhibit 14) recorded 60 mm in 24 hours while stations west of Dundas recorded up to 149 mm. Average is 130 mm, of which 80 mm is estimated to have fallen in the critical period. (11) Derived from Ryde pluviograph and rainfall isohyets (Exhibit 13). (12) Records for the 1889 and 1914 floods are for rural catchment conditions. Records for the 1956, 1961 and 1967 floods are for the developed catchment.
21 6.3 Estimates Based on Australian Empirical Methods
6.3.1 Fitzgerald's Studies - 1983
Fitzgerald analysed the Parramatta River catchment in its predevelopment state using the Pilgrim & McDermott Method (Ref. 13). The estimated 1% probability rural flood was 710 m3/s.
The ultimate urban condition was analysed using a technique developed for the ACT (Ref. 14). Fitzgerald derived correlation factors between catchments for which detailed flood data was available (Woden Valley, Canberra, and Kedron Brook, Brisbane). The 1% probability flood at Lennox Bridge was estimated as 1020 m3/s.
These 1% probability urban and rural catchment flood estimates are shown on Exhibit 11 and are detailed in Reference 15.
6.3.2 The Rational Method - 1984
The Rational Method (Ref. 3) was used to estimate the 1%, 2% and 5% -probability floods in the Parramatta River at the Vineyard Creek and Duck River confluences and at Ryde Bridge.
The time of concentration at Charles Street Weir was adopted as 1.9 hours, as determined (Ref. 2) from the analysis of flows along major drainage paths. The times of concentration for the three downstream points were then calculated by adding on the time of travel of the flood to each of the points. Flow velocities were estimated from the results of channel routing determined by a preliminary analysis using the RSWM (Section 6.5).
The catchment data and flood estimates are given in Appendix D and are shown on Exhibit 11.
The catchment areas modelled are much greater than the recommended maximum of 25 km2 for this method, hence this method may not be applicable to this catchment.
6.4 Estimates Based on the Synthetic Unit Hydrograph Method - Off-
The e Cordery-Webb method (Ref. 16), which was developed principally for rural catchments, was used to estimate the 1%, 2% and 5% probability floods in the Parramatta River.
The rainfall input consisted of standardised temporal patterns for Sydney and the rainfall intensity-frequency- duration data previously derived for Parramatta (Section 4.3). The initial rainfall loss was taken as 5 mm and the continuing loss as 2 mm/hr. The adopted rainfall losses are identical to those used later in the RSWM and are discussed in Section 6.5.3.
22 The analysis was carried out at two locations in the catchment. These were Charles Street Weir and Ryde Bridge. The critical storm durations were found to be 2 hours and 12 hours, respectively. The flood estimates obtained are listed in Table 6.3.
TABLE 6.3
SYNTHETIC UNIT HYDROGRAPH FLOOD ESTIMATES - 1984
Location Flood Peak (m3/s)
Q1% Q2% Q5%
Charles St Weir 610 530 455
Ryde Bridge 1108 966 824
These flood estimates correspond to rural catchment conditions and no allowances can be made for the effects of catchment urbanisation with this setiod. The estimated flood peak of 610 m3/s at Charles Street Weir is shown on E•.hibit 11 for comparison purposes.
6.5 Estimates based on the Regional Stormwater Model (RSWM) - 1984
6.5.1 Background
The RSWM is described in Reference 17 and a diagrammatic representation is given in Exhibit 15. A schematic plan of the catchment subdivisions used in the analysis of the Parramatta River in this study is shown in Exhibit 16, while the isochronal areas are shown in Exhibit 17.
Historical rainfall and pluviograph data was applied to the RSWM to reproduce recorded flows and then to model the synthetic 1%, 2% and 5% probability floods.
As with other sophisticated rainfall-runoff models, successful application depends on the availability of basic data which can be used to calibrate the model. The RSWM requires records showing the temporal and areal variations of flood producing storms. In the case of the Parramatta River catchment the number and distribution of daily read rain gauges was adequate for recent storms ( Exhibits 5 and 6) but little data was available for early flood producing rainfalls.
After calibration, the 1%, 2% and 5% probability synthetic floods were modelled and the results compared with estimates by other methods. 23 6.5.2 Subcatchment Details
The ultimate percentage urbanisation of the upper portions of the catchment to Charles Street Weir was calculated to be 84%. Inspection of recent developments showed that this percentage development could be expected in the near future. The urbanisation of areas downstream of Charles Street Weir to Ryde Bridge was assessed from an examination of recent 1:25,000 and 1:4,000 scale orthophoto maps. Exhibit 2 shows the existing urban, forest and major recreation areas in the catchment. Appendix D contains details of the catchment areas and slopes adopted for each subcatchment in this study. The ultimate urbanisation, averaged over the whole catchment to Ryde Bridge, is expected to be 78%.
Muskingum-Gunge channel routing was used to model the routing effects of the main river channel downstream of the Charles Street Weir because the channel, being a drowned river valley (Section 3.2), is of much larger waterway area than that required to carry the flow alone. Hence the routing effects were judged to be significant and required application of the Muskingum-Cunge channel routing option of the RSWM.
6.5.3 Calibration of RSWM
The RSWMM was initially calibrated using the 1956 and 19061 floods because the rainfall and flood data for these events was the most comprehensive available. The rainfall data for the 1956 and 1961 storms is presented on Exhibits 12 and 13 respectively. The temporal pattern for both storms was derived from Ryde Pumping Station pluviograph data. Though other pluviograph records were available, the temporal pattern exhibited at the various stations in each storm was similar; hence the Ryde pluviograph data was considered to be representative and was adopted . The rainfall depths varied across the catchment as shown by the isohyets on the appropriate exhibits . The isohyets were derived from all the daily rainfall data in the catchment available at the relevant times.
Urbanisation factors for each of the historical floods were estimated from aerial photography and historical data (see Exhibit 1(b)).
Sensitivity analyses were performed using a range of assumed values of rainfall losses and the computed discharges were compared with the discharges at Lennox Bridge derived from the observed flood levels ( Table 6.2 ). On the basis of these analyses and the observation that flood-producing rainfall often occurs after several hours of lighter rainfall it was considered appropriate to adopt rainfall losses commensurate with a wet catchment. The adopted values of rainfall losses for all further analyses were 5 mm initial loss and 2 mm/hr continuing loss. The catchment parameter values adopted are presented in Appendix D.
The results of the calibration procedure using the adopted values of rainfall losses are presented in Table 6.4. The
24 difference between the RSWM estimates and the discharges derived from the rating curve at Lennox Bridge may be attributed to factors such as the base flow rate, which could be significant for a river of this size, variability of loss rates between storms and variability of urbanisation factors. Of these factors the base flow rate is regarded as the most likely source of uncertainty for this river.
A further four historical flood levels were available at Lennox Bridge and thus four further RSWM analyses were performed to verify the initial results. The 1967 and 1975 storms had sufficient rainfall and pluviograph data available to permit the floods to be modelled with confidence. Pluviograph data for these storms is presented on Exhibit 14.
The 1889 and 1914 storms (for which urbanisation was assumed zero, but rainfall losses were unaltered)) occurred before the establishment of any pluviograph station and hence only the daily rainfall data was available. Rainfall totals and temporal patterns were calculated by estimating a rainfall duration on the basis of historical newspaper reports and adopting appropriate temporal patterns from Ref. 3 for these assumed - storm durations. The 18.89 rainfall was assumed to fall over 24 hours, while the 1914 rainfall was assumed to fall over 18 hours. Estimated flood hydrographs were derived using the RSWM, and the computed peak discharges are presented in Table 6.4 for comparison purposes.
Overall the RSWM estimates did not vary from the discharges derived from the rating curve at Lennox Bridge by more than 7% and in the context of the available data the RSWM results were considered to be satisfactory. No parameter values were adjusted in subsequent runs.
25 TABLE 6.4
RESULTS OF CALIBRATION AND VERIFICATION OF RSWM - 1984
Total Rainfall Peak Discharge on subcatchments: ------Lennox RSWM Date Upstream of Downstream of Bridge Estimate Charles St. Weir Charles St. Weir Rating (mm) (mm ) (m3/s) (m3/s)
Calibration
Feb 1956 220 220 585 584 Nov 1961 110 140 510 490
Verification
May 1889 303* 303* 790 754 Mar 1914 279* 279* 710 682 Mar 1967 140 145 550 512 Jun 1975 85 92 110 118
* No pluviograph data available, temporal pattern assumed.
6.5.4 Estimates with Synthetic Storms
The RSWM was then used to estimate the synthetic 1%, 2% and 5% probability floods throughout the catchment. The RSWM parameter values used were as adopted from the model calibration and verification. Rainfall temporal patterns were adopted from Reference 3 and rainfall intensities from Exhibit 7.
Synthetic storms with durations from 0.5 to 18.0 hours were analysed in order to establish the critical storm duration for all required locations from Charles Street Weir to Ryde Bridge. The critical storm duration was found to be 2 hours at Charles Street Weir, 6 hours at the Duck River confluence and 12 hours at Ryde Bridge. The 2 hour storm produced a flood peak of 1600 m3/s at Ryde Bridge compared to a 12 hour storm flood peak of 1695 m3/s. The difference between the two results (6%) was considered marginal. Flood estimates at selected locations are presented in Table 6.5 and the relevant values are shown on Exhibit 11.
26 TABLE 6.5
RSWM FLOOD ESTIMATES WITH SYNTHETIC STORMS - 1984
Calculated Peak Discharges (m3/s) RSWM ------Location Link 1% 1% 1% 2% 5% No. 2 hr 6 hr 12 hr 2 hr 2 hr (Ex. 13)
Charles St. Weir 1.02 1050 990 980 915 780 Duck River Confl. 1.05 1330 1335 1330 1150 980 Ryde Bridge 1.07 1600 1625 1695 1480 1315
6.6 Previous Flood Estimates
6.6.1 RSWM, Rational and Wash Methods - 1976
In the analyses for the 1976 Report three methods were used to derive flood estimates for the upper catchment without any mitigation works. These were the RSWM (Ref. 17), the Rational Method (Ref. 3), and the Nash Unit Hydrograph (Ref. 18). Table 6.6 summarises the results derived at Charles Street Weir.
TABLE 6.6
FLOOD ESTIMATES AT CHARLES STREET WEIR - 1976
---- Peak Discharges ( m3/s) ------Method Q1% Q2% Q5% 2 hour 2 hour 2 hour
1. RSWM 1030 950 820
2. Rational Method 910 820 700
3. Nash Unitgraph 750 630 540
In the 1976 Report it was decided to adopt the Rational Method results as the most appropriate design values for a drainage system incorporating formalised open channels. The RSWM was used to estimate flows for the proposed alternative retarding basin scheme.
27 6.6.2 RSWM - 1980
For the 1980 Report only the RSWM was used to compute flood flows and to investigate structural flood mitigation options further. Flood estimates at Lennox Bridge are presented in Table 6.7 for the catchment without mitigation works.
TABLE 6.7
FLOOD ESTIMATES AT LENNOX BRIDGE - 1980
Peak Discharges (m3/s) ------Method Q1% Q2% Q5% 2 hour 2 hour 2 hour
1. RSWM 791 653 543
The values given in Table 6.7 are lower than those of the 1976 Report because Muskingum - Cunge channel routing was used, thus inducing significant attenuating effects in the reaches of Toongabbie Creek below Johnston ' s Bridge.
6.7 Design Floods
A comparison of the flood estimates calculated by the alternative methods considered, using the the 1%, 2% and 5% probability synthetic storms, are presented in Table 6.8 (as Methods A - G). The flood estimates at Lennox Bridge and Charles Street Weir are shown on the frequency curve on Cxhibit 11
The 1% probability rural (predeveiopment) flows were estimated by the Synthetic Unit Hydrograph (Method C) and Fitzgerald (Method E-1) to be 610 m3/s and 710 m3/s. The two largest recorded floods in the last 100 years occurred in 1889 and 1914. The peak discharges for these floods were estimated (Section 6.2.2) to have been 790 and 710 m3/s respectively. Based on analysis of the available rainfall data these floods were estimated to be in excess of the 2% probability event.
From the above considerations, a 1% probability rural flood of 710 m3/s was adopted; however, this estimate was not required for subsequent analyses.
28 TABLE 6.f!
COMPARISON OF FLOOD ESTIMATES
Lennox Charles Street Duck River Ryde Bridge Bridge Weir Confluence - Comments Q5% Q2% Q1% Q5% Q2% Q1% Q5% Q2% Q1% Q5% Q2% Q1%
A RSWM (1984) - - - 780 915 1050 1025 1160 1330 1315 1480 1695 Consultant's Regional Stormwater Model
B Rational Method (1984) - - - (698) (820) (913) 730 895 1030 731 923 1081 Based on 1976 Report (11-2) and extended downstream
C Synthetic Unit - - - 455 530 610 - - - 824 966 1108 Clark-Johnstone routing Hydrograph Method (1984) Cordery-Webb 'C + 'K' (Rural only)
0 Rating Curve at Lennox 635 750 830 ------Flood Frequency assignment Bridge combined with does not separate effects of Rainfall Frequency urbanisation over 100 years estimates (1984)
E Fitzgerald's (1983)
1. Rural - - 710 ------Flood frequency correlation 2. Urban - - 1020 ------Canberra, Brisbane
F 1980 Report ( RSWM) 543 653 791 ------Consultant's model
G 1976 Report
1. RSWM - - 820 950 1030 - - - - - Consultant's model 2. Rational Method - - - 698 820 913 ------C = 0.5, Urban 3. Nash Unitgraph - - - 540 630 750 ------Urban regression analysis Urban flows were estimated by the RSWM - 1984 (Method A), Fitzgerald (Method E-2), the RSWM - 1980 (Method F), the RSWM - 1976 (Method G-1), the Rational Method (Method G-2), and the Nash Unit Hydrograph (Method G-3).
Method E-2 (Fitzgerald) was based on flow correlations from catchments in Brisbane and Canberra. Differences between the catchments were significant and the results were considered useful for comparison purposes only.
Method G-2 (Rational) is well accepted for simple catchment calculations though uncertainties in the estimation of the runoff coefficient and time of concentration of the catchment can result in a large range of possible estimates. This method was considered useful for comparison purposes only.
Method G-3 ( Nash UHG) gave the lowest of all the urban estimates and has been reported (Ref. 2) to underestimate flows. The regression equations used in the method were derived from catchments less than half the size of Parramatta River catchment to Charles Street Weir. Hence this method was used for comparison purposes only.
Methods A, F and G-1 (RSWM 1976, 1980 and 1984) were the most hydrologically representative of the methods considered. Each RSWM analysis was different in that all rainfall and catchment data was re-compiled in order to produce relatively independent results. In 1976 the catchment analysed was that to the Charles Street Weir, A large range of flood mitigation options was investigated. The analyses featured conventional routing along all reaches. In 1980 the catchment analysed was that to Lennox Bridge. One specific flood mitigation option consisting of three retarding basins was investigated. The analysis featured modified routing in the river reaches.
The RSWM - 1984 flood estimates at Charles Street Weir were based on calibrated model parameter values. The RSWM-1984 flood estimates were generally consistent with those calculated by the other methods and were regarded as being the most reliable and were accordingly adopted. The RSWM is also capable of providing discharge hydrographs at all locations required, which none of the other methods considered is able to do. The adopted peak design flows throughout the catchment for the 1%, 2% and 5% probability floods are presented in Table 6.9 and are shown in Exhibit 18.
30 TABLE 6.9
ADOPTED PEAK DESIGN FLOWS
Critical Peak Discharges (m3/s) Storm RSWM Duration ------Location Link (hrs) Q1% Q2% Q5% (1) (2)
Toongabbie Creek 1.00 2 710 615 525 Darling Mills Creek 2.00 2 450 385 330 Parramatta River at Headwaters 1.01 2 1065 925 790 Charles Street Weir 1.02 2 1050 915 780 Vineyard Creek 3.00 1. 120 110 90 Parramatta River at Vineyard Creek 1.03 2 1070 930 795 Subiaco Creek 4.00 1 190 170 140 Parramatta River at Subiaco Creek 1.04 2 1170 1020 865 Duck River_ 5.00 6 (3) 345 290 265 Parramatta River at Duck River 1.05 6 1330 1160 1025 Various Tributaries 6.00 1 255 230 195 Parramatta River at Tributaries 1.06 12 1420 1220 1100 Hasiams Creek 7.00 2 190 165 140 Powells Creek 8.00 2 140 120 105 Haslams, Powells Creeks Confluence 7.01 2 335 290 250 Parramatta River at Ryde Bridge 1.07 12 1695 1480 1315
Notes: (1) Refer to Exhibit IB (2) Storms ranging from 0.5 to 18.0 hours were analysed (3) Relatively large catchment with flat slopes (Appendix D)
6.8 Effect of Retarding Basin Proposals
Twenty-two retarding basins were proposed in the 1976 Report, having a total flood storage of 6.4 million cubic metres, to be constructed in the catchment upstream of Charles Street Weir in order to lower flood discharges and levels downstream of the basins. It was shown that at the outlet of the study catchment, Charles Street Weir, flood discharges would be reduced as follows:
for a 5% probability flood from 700 m3/s to 380 m3/s, and for a 1% probability flood from 910 m3/s to 600 m3/s.
The proposal was not formally adopted and subsequent detailed investigations indicated that construction of many of the
31 recommended basins either did not have the support of the local drainage authority directly responsible or could not proceed because of further urbanisation or other land acquisition problems. As a result the effect of the remaining retarding basins was substantially less at Lennox Bridge than earlier anticipated.
The 1980 report indicated a possible reduction in peak 1% probability flows at Lennox Bridge of between 5% - 29% depending on land availability and the alternative basin schemes proposed.
Although some basin works are still proposed and others are being designed by the Consultant or under construction, a total of six (6) retardation basins in all, it is obvious that the earlier proposals cannot, be achieved. Recent estimates (Ref 20) indicate a maximum peak flow reduction of; 18% for the 2 hour flood producing design storm at Lennon Bridge. Additionally, the effectiveness of the basins on reducing flood peaks downstream of Charles Street Weir in the Lower Parramatta River is further diminished by the longer duration flood producing storms that are critical between Charles -Street Weir and Ryde Bridge, as indicated in Table 6.9. Therefore it is considered that the effect of future possible basins on flood peaks and flood profiles in the Lower Parramatta River is negligible.
32 7.0 ESTIMATED FLOOD PROFILES
7.1 Introduction
Two types of hydraulic models were used to estimate the 1%, 2% and 5% probability flood profiles in the Lower Parramatta River, Duck River, Haslams Creek and Powells Creek. The first model was the Consultant's conventional steady state backwater model. The second model was the unsteady state flow model, USTFLO. The Lower Parramatta River was analysed by both steady and unsteady flow models, while Duck River, Haslams Creek and Powells Creek were analysed by the steady state model only.
For both models, the river geometry is represented by means of cross-sections. The location of river survey cross- section data used in the modelling is shown on Exhibit 3. Frictional losses are represented by Manning's "n" which is a measure of channel roughness.
The calibration of both hydraulic models requires reliable records of historical flood levels and discharges. The available information was limited and, in the circumstances, it was- necessary to make some unverified assumptions. Comparison against historical flood data was undertaken where possible.
7.2 Steady State Flow Model
The most common method of flood flow profile estimation assumes a steady state condition where neither the inflow to the study reach nor the tailwater at the downstream end varies significantly with time. The flow may be non-uniform, that is, the flow may vary from one cross-section to another. These assumptions are usually acceptable where discharge varies slowly with time and the downstream water level is reasonably constant.
The steady state model used in this study is referred to herein as FLOWBD.
7.3 Unsteady State Flow Model
The computer program USTFLO, described in Appendix E.1, was used to model the Lower Parramatta River under unsteady flow conditions. The application of USTFLO to the Lower Parramatta River was considered necessary as the hydraulic conditions in the river channel are subject to variations in flow and tide level and to river storage effects.
The application of the unsteady flow program to Duck River, Haslams Creek and Powells Creek was not justified as storage effects were not considered significant and discharge and calibration data for these tributaries was deficient. Steady state modelling was considered to produce satisfactory results.
33 7.4 Tidal Influences
7.4.1 Storm Tides
From the tidal data summarised in Section 4.5 it was evident that the governing flood levels in the downstream reaches of the Parramatta River and its tributaries may be produced by a storm tide. Hence the levels of storm tides, which include storm surge effects, were included in this study.
The probability of a coincidental peak storm tide and a 1% probability flood peak was considered remote. The joint probability of such an event has not been considered as part of this study but it would be less than 1%.
The MSB provided a frequency curve for high tides at Fort Denison for .,the 30 year period from 1916 to 1945. These recorded tides would include the effects of storm surge, and these results would also be applicable for the Lower Parramatta River. This curve is shown on Exhibit 19(a) and was extrapolated by the Consultant. A peak storm tide level of RL 1.50 m (AHD) was adopted for this study.
7.4.2 - Downstream Boundary Condition
Both steady and unsteady flow modelling requires the definition of downstream boundary (tidal) conditions. The critical flood situations for flow analyses were assumed to coincide with Mean High Water Springs (MHWS). The starting level at Ryde Bridge for the steady flow analysis was taken as RL +0.66 m (AHD), which is approximately Mean High Water Springs.
For the unsteady flow analysis a downstream boundary condition equal to the tide level variation was adopted. A sinusoidal curve was fitted to a high spring tide with an amplitude of 0.66 m. The adopted "design" tide cycle is shown on Exhibit 19(b), together with observations made by the PWD of the tidal variation in the Parramatta River at four locations on 2 February 1983. The location of the tide gauges is shown on Exhibit 19(c).
The travel time of the tide from Ryde Bridge to Charles Street Weir was of interest in the unsteady flow modelling as it affected the timing assumed for the flood hydrograph in relation to the tidal fluctuation at the downstream boundary.
An approximate estimate of the travel time of the tidal wave was given by the shallow water wave celerity formula as approximately 0.5 hour.
Observations of travel times by the MSB indicate an elapsed time of 15 minutes from high tide at Fort Denison to high tide at the head of Duck River. The recent observations by the PWD, shown on Exhibit 19(b), indicated that differences in travel time between the three upstream gauges appear to be very small.
34 The difference in travel times assessed by the above methods is small. The estimate of 0.5 hr was considered satisfactory for assessing the relative timing of flood hydrographs and peak tides.
7.5 Lower Parramatta River
Both steady state (FLOWBD) and unsteady state. (USTFLO) hydraulic models were established for the Lower Parramatta River. Whilst the unsteady state model is more representative of actual physical river conditions, the steady state model was established to assess the potential difference in results between the models and determine the applicability of the steady state model for future design runs.
The steady state model, being simpler in application, was also used for initial sensitivity testing with respect to flow and roughness coefficient Manning's "n".
7.5.1 Testing of Hydraulic Models
Generall.y the calibration of the hydraulic models is achieved by fitting calculated flood profiles to observed flood profiles. The process requires a series cf flood levels and discharges along the river reach or, for unsteady flow modelling, a flood hydrograph. Data suitable for use in calibrating the models for the Lower Parramatta River was limited and hence the fitting process required several assessments. Limited calibration was achieved by adjustment of parameters such as Manning's "n" and bridge losses.
The relevant historical flood levels as presented in Appendix C . were plotted on Exhibit 20 for the Lower Parramatta River downstream of Charles Street Weir, although this data is subject to uncertainties in both level and time of observation. The flood profiles derived in the 1980 Report for the reach upstream of Charles Street Weir to the Marsden Street Weir are also presented. While these profiles were the result of physical hydraulic model studies it should be noted that flood levels downstream of Lennox Bridge were determined in part by a simple steady state backwater analysis along the Parramatta River starting at the Duck River. Because of the constriction at Lennox Bridge, levels downstream of the bridge were relatively unimportant and were not refined as part of the 1980 report (Ref 6).
A number of trial analyses were performed using the steady state and unsteady state models, with a range of flows and Manning's "n" tested. Details of the testing procedure and the results are presented in Appendix E.2 and shown on Exhibit 20.
35 On the basis of these trial flood profiles, the available historical flood levels and the Consultant's experience, it was concluded that:
(a) A value of Mannings "n" in the lower reaches of the Parramatta River below Duck River of 0.025 and above the Duck River of 0.035 should be adopted for the hydraulic model.
(b) The 1980 Report flood profiles below Lennox Bridge are probably high but this finding does not affect estimated levels in the 1980 Report upstream of Lennox Bridge.
(c) The results from the unsteady state analyses were lower than those from steady state analyses. This was due to fundamental differences in the theoretical basis of the two methods. The difference in computed flood levels was greatest in the lower reaches of the river where storage effects in the drowned river valley were greatest. At Charles Street Weir the two methods gave similar results. It was concluded that the USTFLO model represented flow conditions in the lower reaches of the Lower Parramatta River more appropriately than the FLDWBD model and hence the USTFLO model was adopted for modelling the Lower Parramatta River.
(d) The choice of starting tide level up to RL 0.66 m (AHD) did not have a significant effect on the flood profiles above the Duck River confluence.
7.5.2 Design Flood Profiles - Lower Parramatta River The Lower Parramatta River was modelled by the unsteady state model USTFLO for the 1%, 2% and 5% probability floods calculated by the RSWM-1984. Adopted peak design flows are presented in Table 6.9. The modelling was undertaken using a critical storm duration of 2 hours as determined from the hydraulic model testing, Appendix E-2,(b). Boundary conditions were a semi-diurnal tide cycle at Ryde Bridge with amplitude 0.66 m about MSL and inflow hydrographs from all streams from Charles Street Weir to Ryde Bridge.
In the downstream sections of the river, tide induced flooding was found to be the critical situation. For this reason, a storm tide level of 1.5 m (AHD), as shown on Exhibit 19, was adopted as the critical level in the downstream sections of the river.
The flood profiles for the tidal reach of Parramatta River between Charles Street Weir and Ryde Bridge are shown on Exhibits 21-1 and 21-2 and a plan showing the design flood levels is given on Exhibit 23.
The flood profiles show that tidal effects are dominant between Ryde Bridge and Silverwater Bridge. Therefore the choice of Ryde Bridge as the downstream limit of the study was justified.
36 7.6 Duck River
The profiles for the reach of Duck River from its confluence with Parramatta River up to the Mona Street Bridge were estimated using the steady state program FLOWBD. This approach was adopted because, unlike the Lower Parramatta River, the effect of channel storage was relatively small. In addition, the steady flow analysis is much simpler to apply and it is questionable whether the use of the more complex USTFLO program is justifiable where historical discharge and flood level data is lacking.
7.6.1 Modelling Procedure
Due to the range of possible flow and tailwater conditions a number of design combinations were modelled to identify the flow conditions which would produce peak flood levels along the river. The following combinations were investigated:
(a) Steady inflow (1%, 2% and 5% peak discharges) from the Duck River catchment with the tide level at the Parramatta River confluence at MHWS.
(b) Steady inflow (1%, 2% and 5% peak discharges) from the catchment with water levels at the Parramatta River confluence set at the equivalent (1%, 2% and 5%) probability flood levels.
(c) Zero inflow in Duck River with a peak storm tide in the Parramatta River.
The 1%, 2% and 5% probability flood peaks, estimated for the Duck River at its confluence with the Parramatta River, were as given in Table 6.9. For points upstream of the confluence, the design discharges were reduced by a factor equal to the catchment area ratio raised to the power 0.7.
A Manning's "n" value of 0.035 was adopted based on the Consultant's previous experience and field inspections.
Insufficient flood level data and no discharge data was available to allow verification or calibration of model parameters. However, model results were compared against the limited historical flood levels as described in Section 7.6.2 below.
7.6.2 Design Flood Profiles
The adopted flood profiles are shown on Exhibit 22(a) and a plan showing the design flood levels is given in Exhibit 23.
It should be noted that upstream of Chainage 1040 on Duck River profiles calculated using the three different downstream boundary conditions tend to converge. Downstream of this chainage the profile using the higher Parramatta River downstream boundary condition was adopted as the most appropriate profile.
37 The profiles calculated made provision for head losses at the railway and Parramatta Road bridges of 0.4 m and 0.5 m respectively. The profiles were compared with three flood levels recorded in the study area for the flood of 15th April 1969. The pluviograph at Silverwater indicated that the storm on this date had a duration of 2 to 3 hours and a probability of exceedance of 1% to 5%. Two of the three observed flood levels were in reasonable agreement with the estimated flood profile for a 5% probability flood. The most downstream flood level appeared to be low but this may have been the result of the flood occurring at the time of low tide. In this case, while the flood was known to be extremely rare in the Duck Creek catchment where the intense thunderstorm was localised, downstream along the Duck River its probability of exceedance would have been much higher.
Given the limited historical data for hydraulic model calibration, it is considered that the above results represent satisfactory design 1%, 2% and 5% probability flood profiles.
7.7 Haslams Creek and Powells Creek
Flood profiles for Haslams Creek and Powells Creek upstream to the Western Freeway and Pomeroy Street respectively were calculated using the steady state model FLOWBD. Use of the model was based on the same reasons as outlined for Duck River in Section 7.6.
7.7.1 Modelling Procedure
The following conditions were modelled for the creeks:
Haslams Creek
(a) Steady inflow (1%, 2% and 5% peak discharges) from the tributary with the tide level at the Parramatta River confluence at MHWS.
(b) Zero inflow in the tributary with a peak storm tide in the Parramatta River.
Powells Creek
(a) Steady inflow (1%, 2% and 5% peak discharges) from the tributary with the tide level at the Parramatta River confluence at MHWS.
(b) Zero inflow in the tributary with a peak storm tide in the Parramatta River.
The adopted 1%, 2% and 5% probability flood peaks were as given in Table 6.9.
Manning 's "n" value of 0.035 was adopted based on field inspections.
38 7.7.2 Design Flood Profiles
The design flood profiles are shown on Exhibits 22(b) and 22(c) for Haslams and Powells Creeks respectively. A plan of design flood levels is shown on Exhibit 23.
No data was available for the calibration of the model, however during the course of the study an independent report (Ref. 9) on flooding along Haslams Creek was prepared by Rowe & Ennis (1983) for Auburn Municipal Council. The 1%, 2% and 5% probability flood peak discharges estimated were 115 m3/s, 155 m3/s and 220 m3/s respectively. The corresponding values estimated by the RSWM-1984 in this study were 140 m3/s, 165 m3/s and 190 m3/s. Although the two sets of flood estimates differed, a comparison of the 1% probability flood Profile from Reference 9 and the corresponding estimate made with program FLOWED as shown on Exhibit 22(b) does not indicate a significant difference in flood levels along the creek. The FLOWBD profile utilises five surveyed channel cross-sections at the locations shown on Exhibit 3 and is thus considered a more representative result than the result in Reference 9 which is based on aerial and ground survey at a scale of 1:1000.
From the above considerations it appears that the flood profiles contained in Reference 9 support the flood profiles computed for this report. Accordingly, it is recommneded that the profiles shown on Exhibits 22(b) and 22(c) be adopted as the appropriate design 1%, 2% and 5% probability flood profiles. These profiles should, however, be reviewed when further flood observations become available.
7.8 Flow Distribution The average flow velocity through the main channel , left and right overbanks for the 1%, 2% and 5% design floods are illustrated on plan sheets of the study area (Exhibits 24 to 26). These exhibits also indicate the percentage of the total flow which passes through the channel and overbank areas. The exhibits show flow velocity values averaged across the individual sections of the main channel and overbank areas as predicted by the adopted water surface profile model. Localised flow velocities at a particular site may vary from the average velocity and would be influenced by factors such as obstructions, constrictions and proximity to the main river path.
39 8.0 ACKNOWLEDGEMENTS
This study was funded by the State Government and was undertaken by Willing and Partners , Consulting Engineers for the Public Works Department.
In compiling this report, Willing & Partners has been assisted by advice and information from the Public Works Department (PWD), Water Resources Commission (WRC), local Councils, the Maritime Services Board (MSB), the State Rail Authority (SRA), the Metropolitan Water, Sewerage and Drainage Board (MWS&DB), and various other public authorities and local residents.
40 9.0 REFERENCES
1. NSW STATE GOVERNMENT (1985) - "Floodplain Development Manual - Draft", April.
2. SNOWY MOUNTAINS ENGINEERING CORPORATION ET AL (1976) - "Parramatta River Basin Drainage Study". Report prepared for Sydney Western Regional Organisation of Local Authorities, September.
3. INSTITUTION OF ENGINEERS , AUSTRALIA (1977) - "Australian Rainfall and Runoff".
4. SNOWY MOUNTAINS ENGINEERING CORPORATION (1975) - "A Flood and Water Quality Study of the Non-Tidal Section of the Parramatta River Catchment - Stage I Initial Study". Report prepared for Department of Urban and Regional Development, May.
5. NEW SOUTH WALES GOVERNMENT (1978) - "Parramatta River Basin Flood Mitigation", Report by an inter-department committee of officers.
6. SNOWY MOUNTAINS ENGINEERING CORPORATION - WILLING & - PARTNERS PTY. LTD. ( 1980 ) - " Parramatta River Flood Mitigation Investigation ". Report prepared for Water Resources Commission , October.
7. SNOWY MOUNTAINS ENGINEERING CORPORATION - WILLING & PARTNERS PTY. LTD. ( 1981) - "Toongabbie Creek Retarding Basin 3 ". Report prepared for Water Resources Commission , April.
8. WILLING & PARTNERS PTY. LTD. (1980) - "Subiaco Creek - Ponds Creek Drainage Study ". Report prepared for Parramatta City Council , October.
9. E.S. ROWE & ENNIS , CONSULTING ENGINEERS ( 1983) - "Haslams Creek Drainage Study - Parramatta Road to Homebush Bay", Report prepared for Auburn Municipal Council, June.
10. WILLING & PARTNERS PTY. LTD. (1983 ) - " Pendle Hill Creek Trunk Drainage Study". Report prepared for Holroyd Municipal Council, March.
11. WILLING & PARTNERS PTY. LTD. ( 1983) - "Greystanes Creek Trunk Drainage Study - Draft Report". Prepared for Holroyd Municipal Council and Blacktown City Council, June.
12. HENDERSON, F.M. (1966) - "Open Channel Flow", MacMillan.
13. PILGRIM, D.H. & McDERMOTT, G.E. (1982) - "Design Floods for Small Rural Catchments in Eastern New South Wales", Institution of Engineers, Australia, Civil Eng. Trans.
41 14. FITZGERALD, B.J. (1975) - "A Key Station Approach to Rural and Urban Flood Frequencies in the ACT", Institution of Engineers, Australia, Hydrology Symposium.
15. FITZGERALD, B.J. (1983) - "Parramatta River at Lennox Bridge: An Independent Estimate of the 100 Year Return Period Flood", Report prepared for Willing & Partners Pty. Ltd.
16. CORDERY, I. & WEBB, S.N. (1974) - "Flood Estimation in Eastern New South Wales - a Design Method", Institution of Engineers, Australia, Civil Engg. Trans. Vol CE 16, No 1.
17. GOYEN, A.G. & AITKEN, AS. (1976) - "A Regional Stormwater Drainage Model", Institution of Engineers, Australia, Hydrology Symposium, Sydney.
18. RAO, A.R., DELLEUR, J.W. & SARMA, B.S.P. (1972) - "Conceptual Hydrologic Models for Urbanising Basins", Proceedings American Society of Civil Engineers, Hydraulic Division, Vol. 98,HY7.
19. - U.S. CORPS OF ENGINEERS (1977) - "Gradually Varied Unsteady Flow Profiles", Hydrologic Engineering Centre, U.S. Army Corps of Engineers, August.
20. WILLING & PARTNERS PTY LTD ( 1985 ) - " Parramatta River Basin Discharge Estimates ", prepared for the Water Resources Commission of NSW, July.
42 APPENDIX A
PLANS AND SURVEY DATA A.1 LIST OF PLANS AND DRAWINGS
Date Drg. No. Description Scale
Parramatta - CMA Orthophotomap 1:4000 1977 00052-1,4,8 11 1974 U9152-1,2,3,4,6 Merrylands - CMA 1:4000 1974 9152-v,vii,viii,ix Merrylands - CMA It 1:4000 II 1974 U9160-1,2,3,4 Blacktown - CMA 1:4000 II 1975 U9160-5,6,8,9 Blacktown - CMA 1: 4000 1977 U9160-7 Blacktown - CMA 1:4000 II 1977 U0045-3 Regents Park - CMA 1:4000 II 1978 00060-1,2,3,4,7 Epping - CMA 1:4000 1974 U8252-3 Horsley Park - CMA 1:4000 Parramatta - Cadastral" 1:4000 1979 00052-5,6 it 1975 09152 Merrylands - CMA 1:2000 1977 00052-8 Parramatta - Cadastral 1:4000 1978 00052-7,9 Parramatta - Cadastral 1:4000 1979 00052-6,5 Parramatta - Cadastral 1:4000 1980 U0052-4 Parramatta - Cadastral 1:4000 N51 Clyde - Strengthening of 1:48,1:16 Duck River Bridge 1:12 NSWR Duck R. Bridge, Clyde Renewal of Bearings 1:32 NSWR Duck R. Bridge, Clyde Widening for 6 lines for proposed future quadruplication 1:96 Aug 1982 6895 -C2,C4,C10 Silverwater - Sterling Park Site Reclamation for Indust. BP Aust Nominees P/L - Developm. at Vore St, Silverwater 1:500,1:50 circa 1978 - Untitled - Planning Scheme, Ryde 1983 - Duck River Sections, PWD 1:500,1:100 Powells Creek Section, PWD 1:500,1;100 Powells Creek Section, PWD 1:500,1:1000 Powells Creek Section, PWD 1:500,1:100 Preliminary Only, PWD 1983 Vineyard Ck Section, PWD Vineyard Ck, Duck R & Ck Haslams Ck, Powells Ck and Creek Drain, PWD 1:2000,1:500 1949 Plan - Hydrographic Survey Duck River, PWD 2ft:li n 1946 Haslams Ck Improvements, Extension to Main Channel, Little St to Derby St, Plan and Section, PWD Date Drg. No . Description Scale
Jul 1972 NC71/275/C/1 Newington Naval Armaments Depot - Drainage Investigs & Land Filling Operations, PWD 300ft:lin Jul 1972 NC72/09/D/2 Newington Naval Armaments Depot - Tipping Rights Area No. 3, PWD 300ft:1in Jul 1972 NC72/218/B/1 Newington Naval Armaments Depot - Stormwater Drainage into Parramatta River, PWD 300ft:lin Newington Magazine - Detail Survey ASO-NSW 1965 SI 56-5 Sydney - Geological 1:250,000 A.2: LIST OF BENCHMARKS
B.M. No. EL MO LOCATION DESCRIPTION 1 (W.0.42183) 1.861 Nr. Bridge Sth, Elizabeth St. Bolt in coping. 2 10.481 McArthur St. Brass stud, top wall 3 (W.0.41235) 2.928 Drain outlet Sth. Rangihou Cres. B.M. on headwall 4 4.680 Culvert, Morton St. B.M. on culvert 11 5 4.674 11 6 13.776 Lot 30 (No..2) Broughton St. Bolt in kerb 7 6.552 Lot 16 ( No. 30) it t t' 11 8 17.400 NW corner Thomas/Penberton St. 9 15.169 Lot 4/5 (No. 114/116) Thomas St. 10 15.751 Lot 9 (No. 126) Thomas St. 11 16:546 Lot 16/17 (No. 140/142) Thomas St. 12 16.464 Lot 17 (No. 142) Thomas St. 13 " 16.562 ?Lot 17 (No. 142) James Rouse Dr. ? 14 W.0 . 36069 4.568 Culvert, West bank Vineyard Ck. (BM 2215) Bolt top of WW 15 3.443 East of Alan St (culvert) Bolt in headwall 16 6.348 Lot 206 Muriel Avenue Bolt in kerb 17 " 6.915 Lot 223/224 Mary Parade Bolt in kerb 18 5.522 Lot 273/274 Bridge Street B.M. in kerb 19 (W.0.36337) 2.026 Humes Factory, 24-30 South St. Bolt in step 20 " 4:056 Internat.. Combustion, 38-46 Sth.St. Bolt inSWD pit 21 1.248 Bolt on slipway 22 3.477 Lane off W .- end Antoine St. Bolt in abutment wall 23 6.174 Opp. 588/ 589 Antoine St. Bolt in PMG Box 24 7.034 619 John Street Bolt on capstone 25 1.910 South side John St. Bolt in SWC headwall 26 (W.0 .43459) 5.747 544 John St. Bolt in SWC 27 0.837 South end 537 John St. B.M. on Rock 28 7.997 NE/Nowill/John St. Bolt in ELP 29 (W.0 .43459) 6.537 527 John St. (opp. Sylvia St.) Bolt in path 30 " 4.927 NW/Primrose/John Bolt in kerb 31 5.385 NW/Fallon/John BM on kerb 32 1.706 NE corner Naval Store Bolt in conc. base 33 " 2.836 Naval Store Area BM on base of septic tank 34 2.419 1, 11 1 BM on SWC 35 (W.0 .45934) 18.525 SW/Murdock/ Boronia Bolt in PMG box 36 18.506 NE/Trumper/Boronia Bolt in conc. path 37 10.929 Opp. 15/17 Gregory St. Bolt in coping 38 4.839 Drainage Reserve 29 Trumper St. Bolt in rack 39 8.722 SW/Saunders/Trumper Bolt in kerb 40 10.167 NE/Atkins/Saunders Bolt in kerb 41 5.180 S. end Hughes Ave. Bolt in kerb 42 " 2.352 Transmission easement S. Hope St. Bolt in base of Trans.Twr. 43 (W.C.41619) 3.784 N.cnr Waratah/Wharf BM on concrete culvert 44 " 7.046 S. corner Andrew/Wharf BM on kerb 45 " 9.944 Lot 83 Lancaster Ave BM on dwarf wall 46 (W.0.87342) 10.319 No. 24 (Lot 41) Meadow Crecent BM on rock 47 " 22.200 No. 6 Bank St. BM cut on dwarf wall 48 (5.0.50292) 3.144 Lot 25 Rthesay Avenue 8M on rock 49 (W.0.36387) 5.162 Property boundary W. of Margaret St. Bolt in conc . base of post 50 2.440 General store , Mary St. West Bolt in kerb 51 3.422 Moulding Power Plant Bolt in kerb 52 " 2.526 Bk Control Room Bolt in path 53 (5.0.44660) 3.723 Off Concord Rd, opp. King St. BM on kerb 54 3.781 Lot 4 King Street BM on AP 55 " 1.352 Lot 140 Victoria Ave. BM on kerb 56 (W.0.36777) 1.236 West side SWC (Haslans Ck) BM on SWC coping Between P'matta Rd & Trans. lines 7.613 Cnr. Day/Adderley St Bolt in kerb 5.022 Clyde St/Silverwater Bolt in kerb 6.165 Clyde/Sil verwater Bolt in kerb 6.147 Clyde/Picken Bolt in pole 6.098 Picken/Bl axland Bolt in kerb 7.329 Silver/Blaxl and Bolt in kerb 63 " 6.622 Sil verwater/Blaxland Bolt in kerb 64 (W.0.36378) 4.111 Parramatta Rd, East Duck River Bolt in coc. bridge 65 " 7.192 East Duck River Spike in power pole 5.055 Harbord/Martha Bolt in kerb 4.430 D'Arcy St. (west side) Bolt in conc. driveway 4.500 Martha/Deniehy Spike in ELP 3.030 Lot 50/51 Tennyson Bolt in kerb 70 " 3.955 Lot 8/9 Deniehy Bolt in kerb 71 2.785 Deniehy/Tennyson Bolt in kerb 72 (W.0.36022) 5.321 North Railway/James Ruse BM.on MH cover 73 " 4.900 South Main Roads depot, Unwin St. Bolt in culvert 74 " 4.598 Non-metallic Co., Shirley St. BM on kerb 75 (W.0.41086) 5.945 North Grand Ave, opp. Wunderlich Bolt in conc. 76 (W.0 . 52788) 4.126 Sth Grand Ave, east of Arthur St. GBM 8084 Bolt on bridge h/w APPENDIX B
DAILY RAINFALLS IN EXCESS OF 100 mm APPENDIX B
DAILY RAINFALLS IN EXCESS OF 100 mm
(a) STATION: 066046 - PARRAMATTA (1832-1838, 1851-1861, 1870-1876, 1909-1960)
Date Rainfall Date Rainfall Depth mm Depth mm
25.08.1834 132.1 19.04.1927 o 105.9 04.09.1859 106.7 14.10.1929 100.3 23.07.1860 118.6 07.07.1931 0 141.2 17.11.1860 128.0 28.03.1942 139.2 19.07.1873 114.3 20.05.1943 105.9 27.04.1874 107.7 16.04.1946 o 153.4 13.12.1910 * 111.3 16.06.1950 112.8 13.01.1911 o 134.6 07.05.1953 101.6 24.03.1914 * 222.8 08.05.1953 * 100.6 10.11.1917 112.3 27.11.1955 * 116.3 12.01.1918 0 160.3 10.02.1956 0 180.6 11.05.1925 125.5 11.02.1956 * 105.4 25.03.1926 106.7 10.03.1958 0 129.3 16.04.1927 * 119.4 11.03.1958 * 108.0
(h) STATION: 066055 - LIDCOMBE GOLF CLUB ( 1905-1969)
Date Rainfall Date Rainfall Depth mm Depth mm
28.07.1908 * 108.0 16.04.1946 0 122.2 13.12.1910 * 110.5 10.01.1949 * 101.6 13.01.1911 0 133.4 27.07.1952 121.9 09.03.1913 156.0 10.02.1956 0 160.0 15.05.1913 103.9 11.02.1956 * 110.0 24.03.1914 * 122.7 10.03.1958 0 124.5 12.01.1918 0 104.1 07.03.1964 * 101.6 26.07.1922 100.1 17.04.1969 * 144.8 19.04.1927 0 105.4 14.11.1969 * 122.5 07.07.1931 0 107.4 (c) STATION: 066057 - RYDE PUMPING STATION (1893-1978)
Date Rainfall Date Rainfall Depth mm Depth mm
08.02.1895 110.5 02.05.1953 122.2 06.05.1898 149.9 08.05.1953 * 110.2 05.07.1900 102.4 22.02.1954 136.1 31.03.1900 133.4 01.05.1955 103.6 09.07.1904 127.0 27.11.1955 * 148.8 28.07.1908 * 125.7 10.02.1956 o 188.5 19.07.1910 133.4 10.03.1958 0 104.1 13.01.1911 o 135.6 11.03.1958 * 128.3 21.03.1914 116.8 19.11.1961 204.7 12.01.1918 o 140.2 13.05.1962 151.1 25.03.1926 * 105.2 07.03.1964 * 121.9 16.04.1927 * 114.3 10.06.1964 115.8 19.04.19L7 o 101.6 12.06.1964 110.7 07.07.1931 o 177.8 17.04.1969 * 172.7 16.04.1946 0 132.1 14.11.1969 * 124,5 10.01.1949 * 114.8 02.09.1970 121.9 18.01.1951 105.4 09.12.1970 108.0 15.06.1952 101.6 17.10.1972 120.1 26.07.1952 123.2
Notes: * shows records common to two stations o shows records common to all stations APPENDIX C
FLOOD INFORMATION C.1: LIST OF ORGANISATIONS APPROACHED FOR HISTORICAL FLOOD LEVEL INFORMATION
1. Metropolitan Water, Sewerage and Drainage Board.
2. Maritime Services Board.
3. State Rail Authority
4. Department of Main Roads.
5. Auburn Municipal Council.
6. Ryde Municipal Council.
7. Concord Municipal Council.
8.. Parramatta City Council.
9. Mitchell Library.
10. Ryde Historical Society.
11. Commonwealth Department of Defence.
12. Water Resources Commission.
13. State Library of NSW.
14. Parramatta Library.
15. Ermington Library.
16. Parramatta Historical Society.
17. Cumberland Press Library.
18. The Sydney Gazette and NSW Advertiser.
19. The Sydney Morning Herald.
20. The Advertiser.
21. The Auburn Review.
22. The Auburn and District News.
23. The Cumberland Argus.
24. The Parramatta and Hills News. C.2: COUNCIL INTERVIEWS
C.2.1 Auburn Municipal Council
The Auburn Municipal Council is bordered by Duck River to the west, Parramatta River to the north and Powells Creek to the east, and includes Haslams Creek, a major drainage channel discharging into Homebush Bay. However, there are no existing records referring to flooding within the municipality, other than minor local floods attributable to blocked drains, etc.
C.2.2 Concord Municipal Council
Information received from Council included a plan showing the major area of flooding within the municipality. This area is around Massey Park, to the west of Exile Bay, approximately 4 km downstream of the Ryde Road Bridge, and well outside the area for which flood profiles are required. The last major floods experienced in this locality occurred on 15-16th April, 1969 and 13-14th November, 1969 when 613 points (155.7 mm) and 604 points (153.4 mm) of rainfall were recorded, respectively. To quote Council's letter: "Other minor areas of flooding do exist within the municipality; however, records are not readily available of the areas involved, nor of the flood levels." -
C.2.3 Parramatta City Council
Parramatta City Council was the only local government authority which could supply detailed records of flood heights. There are twenty-nine (29) flood levels at twenty locations. The levels were recorded between 1967 and 1974 although some are undated. Information received from Council is included in Appendix B-2. The flood levels were generally recorded in feet to Standard Datum, and have been converted to metres (AHD). The levels are listed in Appendix C-1 and the locations are shown on Fig. 8.
An attempt was made to obtain information at various bridges and bridge sites mentioned in newspaper reports, such as the Broken Back Bridge and the low level bridge at O'Connell Street. Most of these bridges which had been inundated in the past have been either rebuilt or replaced, and no means of determining the floodlevels were found except at Lennox Bridge (Levels 6,8,13,14,31,32) and the Smith Street footbridge (Levels 5,15). These latter two bridges are still in existence.
C.2.4 Ryde Municipal Council
The northern bank of the Parramatta River between Wharf Road and the Ryde Road Bridge is administered by the Ryde Municipal Council. It is almost all Public Reserve and therefore any occasional flooding which may have occurred is not of concern. Council's survey section indicated that Meadowbank Park had at times been flooded due to backing-up of inadequate stormwater drains, but since improvements were made it has been flood free. C.3: FLOOD REPORTS
C.3.1 Early (pre-1889) Flood Reports
The Sydney Morning Herald, published as the Sydney Herald from 1831 until 1842 and then under its present name, provided the bulk of the information. The Sydney Gazette and NSW Advertiser, from 1803 to 1842, provided some interesting but not very useful insights into early flooding problems. A total of seven local newspapers and periodicals were consulted and others which have ceased publication have been perused to no avail. A book entitled "Floods in the Suburbs and Country" did not contain useful information.
Early reports of flooding in Parramatta, while vivid, offered little factual information as to the height of the floods. The first bridge was washed away in 1795. The second bridge was damaged in 1826 and the "Volunteer" bridge on the west side of what is now Cumberland Oval was washed away in the flood of June 1864. Other heavy storms were recorded in 1806 and 1809 with no mention of flooding or flood damage.
C.3.2 May 1889 Flood
In May 1889 extensive reports were made of "phenomenal" rainfall, with 0.44 inches (11.2 mm) being recorded in six minutes, but to quote the Sydney Morning Herald of Monday, 27th May 1889: "Fortunately, not a great deal of damage has been done by floods, despite the heavy fall. Marrickville has, perhaps...... suffered more, though there has been there greater inconvenience than damage." The following day the Sydney Morning Herald carried these reports:
"Duck Creek has swollen to the width of a quarter of a mile" (note - in these early reports there is some confusion between Duck Creek and Duck River.). "From Friday morning until last night .... nearly 17 inches (430 mm) had fallen, which is almost as much as... the whole of last year." "The low lying lands in the suburbs have been submerged and considerable damage has been done, particularly in the neighbourhood of Marrickville, Croydon and Parramatta." "The Duck River is flooded to that extent that it may fairly be described as a restless sea of water. The iron bridge by which the trains cross it, and the line for some distance, are submerged.." "The waters, which were flowing very fast, appeared to have risen 6-8 feet." "At noon on Monday the river [Parramatta River] commenced to rise perceptibly. It nearly reached the top of the Lennox Bridge Arch at 2.00 pm."
The top of the underside of Lennox Bridge arch is given as RL 7.29 in the 1980 Report (Ref. 6) and hence the estimated flood level at the upstream face of the bridge was assumed to be RL 7.2. It was later found (Ref. 6) that this flood level is affected by substantial drawdown effects. Having regard to these drawdown effects the actual flood level at the bridge (i.e. the flood level just upstream of the drawdown) was estimated to be RL 7.2 + 0.7 = RL 7.9 (Flood level no. 1 in Appendix C-1).
C-3 C.3.3 March 1914 Flood
A major storm was recorded in March 1914. On Monday 23rd March 1914, the Sydney Morning Herald had stories of damage to property in Parramatta: .in some areas as much as 3 feet of water invaded the houses." The next day it was reported that "at four thirty o'clock it (the Parramatta River) had reached within a couple of feet of the arch of the Lennox Bridge."
This indicates a flood level of RL 6.7 at the upstream face of the bridge. Drawdown effects were estimated to be 0.6 m and hence the actual flood level at the bridge was taken to be RL 6.7 + 0.6 = RL 7.3 and this is given as level No. 2 in Appendix C-5.
The Cumberland Argus of Wednesday 25th March 1914 provided extensive reports about the flooding, although most reports were of areas outside the study area: "...depth over the roadway of 3 or 4 feet at Pennant Street" (flowing towards the Rose and Crown Hotel, between Ross and Pennant Streets, Parramatta North). "Left hand side of tramway, close to the bridge.. .eight feet of water over bridge" - this possibly refers to Broken Back Bridge. Blaxcell Street Bridge (Granville) where the Duck River overflowed its banks and submerged that structure, the water reaching the first railing on the bridge."
This was reported to be the highest level for thirty years. It was also reported that the undersized culvert under the railway line was responsible. Despite inquiries it was not possible to establish the location of the "Broken Back" bridge. The Blaxcell Street bridge is on Duck Creek, not Duck River, and is upstream of the tidal limit and well outside the study area.
"The water from Duck Creek (River?) found its way into Brunton's Flour Mill, and stretched over into the Clyde Engineering Works." "During Monday afternoon the Parramatta River, near Lennox Bridge, on both sides was a great sight .. . the water on the Park side of the dam and the tidal portion of the river were level. There was no waterfall until after the flood had receded,"
The Argus also referred to the "disastrous storm of 12 months or so ago" at Lidcombe. Flooding was again attributed to inadequate culverts at the railway embankment. It was mentioned that "Auburn escapes" flooding and was "practically immune." No further references were located.
C.3.4 July 1931 Storm
A major storm found reported was on the 7th July 1931, when a cyclone struck Sydney, causing great damage. There were no reports of flooding at or near Parramatta. C.3.5 September 1943 Flood
A storm on the morning of 29th September, 1943 caused extensive flooding of Haslams Creek and Powells Creek on the upstream (southern) side of the railway, outside the study area.
"Fences were washed away, furniture, floor coverings and personal effects were damaged by flood waters and in some cases stock in business premises was either washed away or damaged." - extract from report by the Chief Surveyor, MWS&DB.
A total of 330 points ( 83.8 mm ) of rainfall was recorded at Sydney Weather Bureau between 8 am and 9 am , while 3.68 inches ( 93.5 mm) was recorded at Fairfield between 7.10 and 8.10 am.
Despite the heavy rainfall, no newspaper reports of flooding were found. The above information was obtained from MWS&DB files.
C.3.6 February 1956 Flood
The Parramatta Advertiser of 23rd February 1956 reported that the Parramatta River was 6 feet over the Smith Street footbridge in Parramatta. This gives an estimated flood level of RL 3.4 (Flood level No. 5 in Appendix C-5). It reported:
"Flood damage was ... minor. Serious flooding was prevented ... because of recent completion of drainage programmes. Potential hardship was averted because of a City Council policy to stop building development in areas subject to heavy flooding."
C.3.7 November 1961 Flood
November 1961 produced many accounts of violent storms and considerable damage. The worst of the flooding occurred in the Windsor/Richmond area. The Sydney Morning Herald, the Cumberland Argus and the Parramatta Advertiser all carried reports of flooding in and around Parramatta, although generally at places upstream from the rivers and streams under study. Two people drowned in a canal in Auburn near the bridge at Rawson Street. This canal appears to be Haslams Creek and the Rawson Street Bridge seems to have been where the canal crosses what is now Boorea Street. At the bridge the road was covered to a depth of 3 feet over a distance of 75 yards. There is a photograph in the Sydney Morning Herald showing the top water level at the bridge. The report also mentions a house in Wilfred Street (Lidcombe) being flooded to the top of its windows. The Parramatta Advertiser has a photograph of the Parramatta River flowing under the Lennox Bridge, saying this was an "all time record level". This "record level" appears to be about 1-1.5 metres below the top of the arch, well below those reported in 1889 and 1914 and would indicate a flood level at the upstream bridge face of from RL 5.8 to RL 6.3. A flood level of RL 5.8 m has been adopted and included as No. 8 in Appendix C-5. The paper went on to say that "in Parramatta itself every bridge except Lennox Bridge and Gasworks Bridge (McArthur/Harris Streets) was submerged." The Cumberland Argus has a photograph of the low level bridge at O'Connell Street and mentions that water reached 3 feet up the side wall, since demolished, of the old David Jones' Store in Church Street.
C-5 C.3.8 March 1967 Flood
In March 1967 only the Parramatta Advertiser made any mention of flooding, referring to Harold and Grose Streets, Parramatta, and several factories in the North Rocks area. This flood is also mentioned in the MWS&DB files. It appears to have been mainly due to deficiencies in local drainage around the Brickfield Creek stormwater channel. Localised nuisance flooding was also reported in the adjoining Vineyard Creek and Subiaco Creek catchments.
C.3.9 April 1969 Flood
The Sydney Morning Herald was the only newspaper to report flooding on 15th April 1969, stating that the "Parramatta River was flooded between North Parramatta and Rydalmere."
C.3.10 October 1972 Flood
MWS&DB records indicate flooding and property damage occurred in the upper sections of A'Becketts Creek, Merrylands, on the 16th and Powells Creek, Strathfield, on the 29th. Both areas are, however, upstream of the tidal influence. These floods were attributed to inadequate local drainage channels and, subsequently, improvements to the channels have been carried out at both locations.
C.3.11 April 1974 Flood
On 25th April , 1974 a storm , referred to as the "Anzac Day storm", produced extreme rainfalls over parts of the Duck Creek catchment. The falls were caused by a slow-moving , intense thunderstorm centred over Guildford and Merrylands. There were several reports of flooding of Duck Creek and Duck River upstream of Parramatta Road, outside the study area . The Review Pictorial has a photograph of Euston Road ( Auburn ) showing flooding that was said to be "almost a repetition of the flooding that occurred on 15th April 1969". C.4: PERSONAL INTERVIEWS
C.4.1 The occupants of No. 1 Rangihou Crescent, Parramatta, who have lived at that address for twenty six years had no recollection of specific dates of flooding but said that there had occasionally been "minor" overtopping of the banks. The part of the bank which was levelled for cross-sectional information has not been inundated during the time of their residence. The level at which minor overtopping occurs was determined by survey to be RL 1.9 m (Flood level No. 38 in Appendix C.5).
C.4.2 At Broughton Street, some 500 metres downstream of Rangihou Crescent, residents recalled that about thirty years ago the water reached "the top of the fence posts". This probably refers to the flood of 1956, which was slightly larger than the flood of 1961, and it can be assumed that the existing fence is approximately the same height as the old one. No other floods were particularly remembered, although the land has been submerged on some occasions. From site observations the flood level is estimated to have been RL 2.5 m (Flood level No. 3 in Appendix C.5).
C.4.3 As mentioned in Section 5.2, the Naval Stores on the north bank of the Parramatta River just downstream of the Silverwater Bridge were flooded in 1974. The depth over the concrete floor in two of the buildings was indicated as 4 inches. High spring tides frequently just overtop the banks but no other flood level information was available.
C.4.4 On the south side of the river , downstream of James Ruse Drive, the land is either industrial or recreational. The works manager at Meggit Ltd., Thackeray Street, Camellia, remembered a maximum flood height at a small ( 150 mm dia) pipe outlet occurring " some time in the last sixteen years", but unfortunately could not remember exactly when, although it appears possible that it could have been in 1974. Survey of this flood observation indicates a flood level of RL 2 . 3 m (No. 29 in Appendix C.5).
C.4.5 The company secretary of Southern Cross Machinery Pty Ltd., at the eastern end of Grand Avenue, Camellia , located a company history , showing that no flooding had occurred at the site in the last forty years. This site was filled in the mid 1940s to give a freeboard of one foot for the then known maximum flood height and in 1956 the water level was actually recorded as being one foot below the top of the embankment . The present level of this embankment is approximately RL 1.9, indicating a flood level of RL 1.6 ( No. 4 in Appendix C.5).
C.4.6 Interviews were conducted with occupants of premises backing on to Duck River , between Parramatta Road and its confluence with the Parramatta River. Mr. Horan, of Horan's Steel , Junction Street, Auburn , pointed out a level on a railway culvert discharging into Duck River as the highest level reached during the last forty years. An employee of Philtop Enterprises Pty. Ltd., of Carnarvon Streeet, Auburn , stated that the river had "never been within two feet of the ( private ) railway line ". The Shell C-7 and BP refineries could not supply any information on flooding. Lubrizol Australia of River Street, Silverwater, had not experienced flooding in the period since 1960. The crew at the Fire Station in Adderley Street, Silverwater had no records of any properties being flooded other than a factory at the north end of Duck Street, Auburn, which has a basement excavated below the normal river level. This factory is currently unoccupied, and it was not possible to gain access to it.
C.4.7 Local residents state that the south bank of the Parramatta River near Noller Parade, Parramatta, which features a low stone retaining wall at approximately RL 1.0 m AHD, has never been overtopped by floodwaters. This observation was confirmed by staff at the Accessory Manufacturing Co., Jean Street, Rydalmere, who had been working at the factory for more than 20 years. Residents of John Street, Rydalmere could remember the river rising to within 30 feet of the road during high tides. Regrading of the area many years ago has prevented further tidal flooding. The Naval Armaments Depot at Newington which borders the south side of the Parramatta River from Jamieson Street in a north-easterly direction for over a kilometre has no records of flooding. This river frontage is largely mangrove swamp and floods or high tides have no significant effects. DATE OF No. FLOOD LOCATION / DESCRIPTION RL (AHD) SOURCE RELIABILITY
1. 27.05.1889 Lennox Bridge, Parramatta upstream of drawdown 7.9 Sydney Morning Herald fair
2. 21.03.1914 Lennox Bridge, Parramatta upstream of drawdown 7.3 Sydney Morning Herald fair
3. 1956? North bank Parramatta River, East end Broughton St 2.5 Resident date uncertain
4. 02.1956 South bank Parramatta River, East end Grand Parade 1.6 Factory records poor
5. 02.1956 Smith Street footbridge, Parramatta 3.4 Parramatta Advertiser poor 4.67 Parramatta C.C. good
6. 02.1956 Upstream side Lennox Bridge , Parramatta 6.34 Parramatta C.C. good
7. 1956?* North bank Parramatta River, East side Morton St 3.38 Parramatta C.C.- F.L. 45 date uncertain
8. 11.1961 Lennox Bridge, Parramatta upstream of drawdown 5.8 Parramatta C.C.- photos fair
9. 6.03.1967 East side Vineyard Ck, between Victoria Rd and 8.90 Parramatta C.C.- F.L. 22 good Anderson St
10. 1967? East side Subiaco Ck, opposite Crowgey Reserve 3.82 Parramatta C.C.- F.L. 26 date uncertain
11. 6.03.1967 West side Subiaco Ck, just north of Victoria Road 4.90 Parramatta C.C.- F.L. 27 good
12. 1967? Subiaco Ck, opposite lot 9 Clyde St, Rydalmere 3.18 Parramatta C.C.- F.L. 28 date uncertain
13. 6.03.1967 Upstream side Lennox Bridge, Parramatta 6.10 Parramatta C.C. good
14. 6.03.1967 Downstream side Lennox Bridge, Parramatta 4.72 Parramatta C.C. good
15. 6.03.1967 Smith Street footbridge, Parramatta 5.01 Parramatta C.C. good
16. 15.04.1969 South side Duck Creek, just north of George St 3.95 Parramatta C.C.- F.L. 41 good
17. 15.04.1969 Just west of Duck Ck/ Duck River confluence, Hill St 2.47 Parramatta C.C.- F.L. 42 good
18. 15.04.1969 West side Duck River, just south of Parramatta Rd 4.10 Parramatta C.C.- F.L. 43 good
19. 15.04.1969 Hamilton St, just west of Duck Ck/A'Becketts Ck 3.82 Parramatta C.C.- F.L. 44 good
20. 15.04.1969 West side Duck River , just upstream of Mona St Bridge 6.57 Parramatta C.C.- F.L. 37 good DATE OF No. FLOOD LOCATION / DESCRIPTION RL (ADD ) SOURCE RELIABILITY
21. 16.10.1972 A'Becketts Ck, east end of A'Beckett St 4.00 Parramatta C.C.- F.L. 54 good
22. 25 . 04.1974 South side Duck Creek, just north of George St 5.12 Parramatta C.C.- F.L. 41 good
23. 25.04.1974 Nest side Duck River, just south of Parramatta Rd 3.60 Parramatta C.C.- F.L. 43 good
24. 25.04.1974 Hamilton St , just west of Duck Ck/A'Oeckett's Ck 4.84 Parramatta C.C.- F.L. 44 good a 25. 25.04.1974 A'Becketts Ck, east end of A'Beckett St 5.00 Parramatta C.C.- F.L. 54 good
26. 25.04.1974? West side Duck Creek , just south of Parramatta Rd 3.82 Parramatta C.C.- F.L. 75 good
27. 25. 04.1974 Duck River, under Mona St Bridge 6.06 Parramatta C.C.- F.L. 37 good
28. 26.04.1974 East side Duck Creek, just upstream of Memorial Or 6.41 Parramatta C.C.- F.L. 74 good
29. 1974? South bank Parramatta River, East side Thackeray St 2.3 Works Manager poor
30. 1974? North bank Parramatta River, Naval Store Ermington 1.5 Stores Personnel fair
31. 21 .06.1975 Upstream side Lennox Bridge , Parramatta 3.20 Parramatta C.C. good
32. 21.06.1975 Downstream side Lennox Bridge , Parramatta 3.11 Parramatta C.C. good
33. 21.06.1975 Upstream side Charles St weir, Parramatta 2.98 Parramatta C.C.- F.L. 76 good
34. 21.06.1975 West side Subiaco Ck, No. 11 Bridge St, Rydalmere 3.68 Resident good
35. 4.03.1977 Upstream side Charles St weir, Parramatta 2.96 Parramatta C.C.- F.L. 76 good
36. 20-03.1978 Upstream side Charles St weir, Parramatta 2.95 Parramatta C.C.- F.L. 76 good
37. 2.11.1981 Upstream side Charles St weir, Parramatta 2.33 Parramatta C.C.- F.L. 76 good
38. Unknown North bank Parramatta River, Rangihou Crescent 1.9 Resident poor
39. Unknown East side Duck River, near confluence Duck Ck 1.7 Factory Manager poor
* Note: A question mark alongside the date of a flood indicates that the actual date was not recorded. APPENDIX D
FLOOD ESTIMATES DATA D-1: RATIONAL METHOD FLOOD ESTIMATES FOR PARRAMATTA RIVER - 1984
Total Area Time Of Flood Peak Location Contributing Concentration (m3/s) (km2) (hrs)
Charles Street Weir 107.7 1.9 (913)* (820) (689)
Vineyard Creek confl. 112.4 2.2 924 830 710
Duck River confluence 167.5 2.8 1030 895 730
Ryde Bridge 212.0 3.5 1081 923 731
* Adopted from 1976 Report
A runoff coefficient "C" value of 0.5 was adopted for all storms. "C" is a function of the degree of urbanisation, the rainfall intensity and other catchment features. The rational method estimates were prepared on the basis of a fully urbanised catchment with appropriate allowance for Council's development controls. D.2: RSWM SUBCATCHMENT DETAILS AND ADOPTED PARAMETER VALUES - 1984
Sub- Description Subcatchment Details Adopted Parameter Values catchment Area Slope rani- Initial Continuing No. (km2) (%) sation Rainfall Rainfall % Loss (mm) Loss (mm/h)
1 Toongabbie Creek 70.1 0.33 91 5 2
2 Darling Mills and 30.4 0.85 66 5 2 Hunts Creek
3 Residual to 7.2 0.90 84 5 2 Charles Street Weir
4 Vineyard Creek 4.58 0.90 70 5 2
5. Subiaco Creek 9.77 0.56 80 5 2
6 Duck River 45.15 0.15 80 5 2
7 Various 10.38 1.20 80 5 2 Tributaries
8 Haslams Creek 19.92 0.20 50 5 2
9 Powells Creek 12.39 0.20 60 5 2
Residual River 2.06 0.05 85 5 2 Area
Total 211.95 Mean 78
D-2 APPENDIX E
UNSTEADY STATE FLOW MODEL, USTFLO E.l: PROGRAM DESCRIPTION
The program was originally obtained from the Flood Control Branch, Tennessee Valley Authority and modified at the Hydrologic Engineering Centre.
The purpose of the program is to simulate movement of hydraulic transients by solving the basic equations of unsteady flow, the St. Venant equations, in one dimension.
In general, the program permits the user to prescribe either a stage change or a discharge change at two boundaries and to calculate the resulting profiles of discharge, elevation and velocity throughout the entire distance between the two boundaries at points in time as the transient moves in either the downsteam or the upstream direction.
The upstream boundary may be prescribed by a discharge hydrograph or a stage hydrograph. Points are coded as co-ordinate values, for example, time and discharge or time and elevation and randomly spaced time co-ordinate points may be utilised.
Boundary conditions at the downstream end may be prescribed with a rating curve in addition to the stage or discharge hydrograph. A rating curve is-entered as stage and discharge co-ordinate points, spaced at random intervals, as required.
The program also permits use of a rating curve to depict an upstream boundary condition. This, however, is recommended only when flow is in the upstream direction, in which case the rating curve would be specified in terms of negative discharges. When flow is in the downstream direction, a rating curve at the upstream boundary does not represent an independent condition and therefore is not used as a boundary condition.
Because the basic equations for unsteady flow are complex, a numerical integration solution technique is required. As a result, significantly more calculations are required to route a flood with this program than with traditional routing programs. If several flood hydrographs are to be routed, this program would probably be best suited to assist in developing routing criteria, and the actual routing studies would be most economically performed by a modified PuTs or Muskingum routing technique.
The program provides a one-dimensional solution of the unsteady flow equations, and does not account for the time required for water to flow laterally out of a channel and occupy storage on a wide floodplain. It is not a network model. Lateral inflow can be accommodated, but the routing accommodates only one main channel. The program will not route flow in an initially dry channel. Streams that are "hydraulically steep", or near to it, cannot be accommodated. It does not automatically calculate the lateral outflow that would occur-should a flood overtop the valley wall and spill over into the next basin. Infiltration losses are not calculated. Routing a bore is approximated, but not handled in detail. Flow is assumed to be well mixed so that density-stratified flow, which often occurs near an estuary, is not accommodated.
One application of the program is routing floods along rivers or through reservoirs. This, however, is not intended to be the E-1 principal use because there are other, simpler techniques for handling normal flood routing problems. The primary value of this program is that it handles flood routing when the hydraulics of flow are complex. For example, a flood may be routed in a channel which is subject to tidal action. Likewise, it is possible to calculate the discharge that results from tides such that the water flows downstream on the ebb and reverses to flow in the upstream direction on the rising tide. These are examples of hydraulic transients that cannot be simulated by traditional hydrologic routing techniques.
This program was obtained initially for use in calculating the outflow hydrograph at a breached dam and routing that hydrograph to downstream points of interest to determine the peak elevations and time of travel of the dambreak flood wave. Because of the program's flexibility, it has also been used for many other applications. Some examples are: (1) Routing hydraulic transients that are generated in a navigation canal by lock operation. (2) Routing transients that result from the starting or stopping of hydro-electric power generators. These emanate in both directions from the power house with a positive wave moving in the downstream direction and a negative wave moving in the upstream direction when discharge is increased. (3) Calculating flow velocities in a navigation canal connecting two reservoirs. The program is particularly useful for this application since the operating stage of the reservoirs can be prescribed and resulting discharges and flow velocities calculated in the connecting canal. (4) Calculating the portion of the loop effect in a stage discharge rating curve that is produced by the passing of a flood event. (5) Calculating velocities and depths in tidal rivers subject to flow reversals. E.2: MODEL TESTING - LOWER PARRAMATTA RIVER
The following trial analyses were performed and the results are shown on Exhibit 20:
(a) Three steady flow runs (Runs A, B and C) using the steady state program (FLOWBD) to assess the sensitivity to of the computed flood levels to variations in the assumed value of Manning's "n". The 1% probability flood peak was assumed to enter the tidal reach of the Parramatta River at Charles Street Weir with downstream tributary inflows as presented in Table 6.9.
In effect this modelled the occurrence of critical flows simultaneously at all points along the river. Even though the 1% probability critical storm durations between Charles Street Weir and Ryde Bridge ranged from 2 to 12 hours, as shown in Table 6.5, the variation in peak discharges along the river from storms of different durations was small. Hence it was considered reasonable for the purpose of modelling to assume that the critical flood levels could occur simultaneously along the river in the one flood.
The tide level fixed at RL 0.66 m (AHD) at Ryde Bridge. Mannings "n" was constant along the entire reach using values of 0.035, 0.030 and 0.025 for runs A, B and C respectively.
(b) One unsteady flow run (Run D) using program USTFLO to compare the estimated unsteady profile with the corresponding steady flow profile with a Manning's "n" value of 0.030. The 1% probability flood hydrograph from the 2 hour storm was assumed to enter the tidal reach of Parramatta River at Charles Street Weir with tributary inflows from Vineyard Creek, Subiaco Creek, Duck River, various minor tributaries, Haslams Creek and Powells Creek.
Two initial analyses were performed using the flood estimates from the 2 and 6 hour storms in order to assess the critical storm duration for peak flood levels. The 2 hour duration storm resulted in higher flood levels than the 6 hour storm at all computation points on the river. The 2 hour storm was subsequently used to estimate the peak flood profiles for the unsteady model.
A semi-diurnal tide cycle with an amplitude of 0.66 m about MSL at Ryde Bridge was assumed as the downstream boundary condition. The plotted profile was obtained by adjusting the phasing of the inflow hydrographs with the tide cycle to maximise river levels.
(c) Two steady flow runs (Runs E and F) using FLOWBD with a starting level of RL 0.00 m (AHD) and a flood discharge of 540 m3/s. This flood discharge is approximately the magnitude of the 1956 and 1967 floods as calculated by the RSWM-1984 (Table 6.4). In the first run it was assumed that Manning's "n" was constant throughout the river reach at 0.025 while in the second Manning's "n" was increased to 0.035 above Duck River. The second flood profile was close to the observed profile. Therefore a Manning's "n" equal to 0.025 below Duck River and 0.035 upstream thereof was adopted for all further hydraulic (unsteady and steady state) modelling of the Lower Parramatta River. E-3 (d) One (Run G) steady flow profile commencing at tide level RLO.66 m (AHD) was evaluated to show the effect of the variation of tide level at Ryde Bridge. In other respects the parameter values were the same as with Run F, which started at RL 0.00 m (AHD). The two profiles merged just upstream of the Duck River confluence.
(e) The sensitivity of the computed flood profiles to the adopted design discharges and Manning's "n" values was tested with two sets of trial runs using program FLOWBD. These trial runs involved, in the first place, increasing and decreasing the assumed peak discharges by 20%. These runs were followed by similar adjustments to the adopted Manning's "n" values. At the Duck River confluence, the estimated flood level was found to be relatively insensitive to variations in the peak discharge or Manning's "n" values. The computed flood levels at Charles Street Weir were found to be more sensitive to variations in discharge and Manning's "n". A 20% change in either of these parameters causes the estimated flood level to vary by up to approximately 0.8 m at Charles Street Weir. m x x H W H PACIFIC
UPPER PARRAMATTA OCEAN RIVER CATCHMENT a FPIanELD
LEGEND Period of devetopment D Up to 1856 I= 1856 to 1881 1881 to 1917 NZE 1917 to 1947 fiz;;^ 1947 in 1956 1956 to 1967 UM 1967 to 1975 I Open space
(b) UPPER CATCHMENT URBANISATION
LOWER PARRAMATTA RIVER FLOOD STUDY
LOCALITY AND URBANISATION MAPS EXHIBIT I I
RYDE BRIDGE CATCHMENT AREA 212km2
LEGEND
SUB-CATCHMENT No.'s CREEKS AND RIVERS CATCHMENT BOUNDARY -• - SUB-CATCHMENT BOUNDARY
Hi URBANISED AREA (T8°!°)
T"q PASTURE, PARKLAND, ETC. (13%)
FOREST (9%)
s213CO5 STREAM GAUGING STATION & No.
PROPOSED MAJOR RETARDING L? BASINS (1980)
0 1 2 3 4 kilometre SCALE
LOWER PARRAMATTA RIVER FLOOD STUDY
CATCHMENT MAP EXHIBIT 2 L INOX R B+1DGE VICTORIA!
R yER
PAR.RAA4ACT
GRANVILLE
-CHH 384
CH 4306
CH 4714 MONA ST. CH 4840--- LEGEND
CH 7500 CROSS SECTION
197T- DATE OF HYDROGRAPHIC SURVEY
LOWER PARRAMATTA RIVER FLOOD STUDY NOTES 0.5 0 0.5 1 kilometre LOCATION OF SURVEYED I• SURVEY BY WILLING & PARTNERS SHOWN 3 RIVER CROSS.SECTIONS 2• PREVIOUS SURVEY SHOWN + SCALE 3. ALL OTHER SURVEY BY PWD EXHIBIT 3 4, BENCHMARKS LISTED IN APPENDIX A-2 AHU Im) (ft) (fit (m{ RELATIVE VALUES OF LEVELS PRIMARY REFERENCE STATION - - SYDNEY (m) (1t) (m) Iml
SUBTRACT 0•046m from BENCH MARK Brass plug in northern wall of Lands Dept STANDARD DATUM to get AHD
8.775 8.821 28.94 9x87 9.714
Railway ConStruction & Existing 0.847 01893 2.93 5•B6 1.786 sZL-N, 4C__,•
0'810 0.856 2.81 5.74 1-750 Sydney Water Board - Sewerage
Mean High Water Springs IMHWS) 1.564 5.13 1.609
0.551 0.597 1.96 4-89 1-490 Sewerage. & Health Board Maps
Mean High Water Level (MHWL) t.442 4.73 1.480
Sydney Water Board - Water. Harbour D•472 0.518 1.70 4.63 1-411 & Rivgrs . ^_ ^^ ,_,^ ^„ ,,,•,
0.457 0503 1.65 4.58 1-396 Lands Department
Mean High Water Neaps (MHWN) 1.320 4-33 1.351
Water level at a particular time
Minus M an Sea Level M L 0.046 000 0-00 2.93 C-893 Aj ARD _ e 0-893 2.93 0938 Military Topographical NSW Main Roads Public Works (Dam Construction) Public Transport Commission City Council (Since 4.10-27) M o wW a t r ea s ML WN) 01488 1.60 0.54 v
can wW ter Level (MLWL 0.41 0
S S t rSurin s MLWSI c 0.244 0-80 0-28
Old Zero at Fort Denison 0.12 0.41 Tide Guage
'or on LowWaterIISLW) Oq 0.00 H dr ogr a„^h+c Datu ^NSWI Maritime 0.0 Services Board New uniform Data Zero on Primary ra Reference Station at Fort Denison from 11 54 v
in o 2 0 2 z
E N A z O < ^ m N Q St x at Li w S
Oa atm IN- Q N w w ^0 w
p NOTE• There is no constant comparison between Tidal Values and any Land Datum.The Maritime Services z d 4 can supply tide values (related to Zero tide guage) Board N The correction from Standard Datum to AHD (subtract 0-046m1 only applies in the neat vicinty of the Lands Department plug (inner Metropolitan Area), Correction values for other locations throughout NSW should be acertained from Survey Co Ordination Branch, Crown Lands Officer Lands Dept.
I __j
NOTE -- LOWER PARRAMATTA RIVER FLOOD STUDY 1. INFORMATION SUPPLIED BY DEPARTMENT OF LANDS. RELATIONSHIP BETWEEN SURVEY DATUMS EXHIBIT 4 STATION LOCATION DATE NOT E 90 1900 10 20 30 40 1950 NUMBER 1880 60 70 1980
066013 CONCORD GOLF CLUB 066019 EASTWOOD -000OS AVE. 066020 EPPING -CHESTER ST. 77 M 066038 MERRYLANDS 066046 PARRAMATTA RECORDS : 1832 - 38 , ' 8 51 - 61 , 1870 - 76 066047 PENNANT HILLS 066048 PENNANT HILLS WEST NO RECORDS AVAILABLE 066050 POTTS HILL PUMPING STN. 066055 LIDCOMBE GOLF CLUB ,; -v , 066057 RYDE PUMPING STN. 066064 CONCORD- WALKER HOSPITAL 066082 CONCORD WEST - PLASTER MILLS 066085 AUBURN - WAGON WORKS 066087 EASTWOOD BOWLING CLUB 066091 BURWOOD 2 - PUBLIC SCHOOL 066092 DURAL 066109 HUNTERS HILL 2 - THE BUNGALOW 066121 CHESTER HILL 066124_. PARRAMATTANORTHH 066134 GRANVILLE -. SHELL REFINERY PtUVIOGRAPH RECORDS LOST 066135 SILVERWATER 066164 STRATHFIELD COUNCIL 066169 VILLAWOOD ARCHIVES 066174 DUNDAS 067001 CASTLE HILL 2 067005 FAIRFIELD POST OFFICE 067006 FAIRFIELD MWS&DB 067008 GUILDFORD 067011 GRANVILLE 067012 KELLYVILLE MEESE= 067019 PROSPECT DAM 067026 SEVEN HILLS EXPERIMENTAL FARM 067032 WESTMEAD - AUSTRAL AVE . No RECORDS AVAILABLE 067053 CASTLE HILL 1 NO RECORDS AVAILABLE 067059 BLACKTOWN - KILDARE ROAD 067070 MERRYLANDS - WELLSFORD ST. .Mai 067080 WINSTON HILLS 067089 PENNANT HILLS C.F.S. P RRAMATTA COUNCIL
LEGEND
-^ DAILY READ GAUGE
PLUVIOGRAPH LOWER PARRAMATTA RIVER FLOOD STUDY RAINFALL RECORDS EXHIBIT 5 INFORMATION SUPPLIED BY BUREAU OF METEOROLOGY 066020 EPPING (CHESTER ST. ) 1869
066109 066019 HUNTERS HILL EASTWOOD 067089 WEST PENNANT ILLS (C. F.S.) 1914,1967 066087 1956, EASTWOOD 1961, BOWLING CLUB 1967
066082 CONCORD WEST 66091 ^s ®BURWOOD PUBLIC . SCHOOL \FFk ^°'•---^...
STRATHFIELD . 066164
11914 ,1956
1 1956, 1961,1967
0 067070 MERRYLANDS (WELLSFORD ST.)
LEGEND DAILY READ RAIN GAUGE
* PLUVIOGRAPH STATION LOWER PARRAMATTA RIVER FLOOD STUDY 1914 INDICATES DATA USED IN MODEL STUDIES LOCATIONS OF 4 kilometre RAINFALL STATIONS SCALE EXHIBIT 6 500 , . .I,T. _ _.S_. ..5 ! .F 500 ^ `I . i::.: I E I r -•i.. T T" 11 At ii fi. 400 i s : .. t ;,! { I l , t, 1 11r f _ f f , a _ 400 . I Y + f ' it 4 1 d i ^r '. i' t { r. ! ! , t } ,. 111 !. { 1 ,! , 4 l i f f '! 1 1 ^ 11, ^ I I 300 E 300 I. { 1( rf ;.}.t ! !; i f I : lII '° 1 1:4 if, p t, I , E t .. .. .1 .. j t _ ,,. 200 200 1 Y ^ r , ^ .1 t- ; . j e , i . , I .. { • {
• f t t 1 ••r T N n: fit . p. I„ I I f ,.f _C 11 r t , I, t i,•a ^ ^...... }t- I I ^^`( " I ^ t, r i -7 ^i f ^+•^^ ^ . i,lr,„1 . ... 1 100 • 1 M t 100
L. I I ^ 1, y ll^ 1 I4I' t i ^^, ft t ^ I } C ! + E I 1 I^^ i ^C1 1 ' ^ i yy .Y: f ( 1 ^ i1k I } , I!li^^{'} '; flf^ ^ IM• ^ • ` ^^ j 1I^fE, t^ f t 1 J J' r l -,-^^^111 . } {! I f f : ' t I }^ } f E ^){^ E 1 II .!. iI , { t ' ^. ^ `1 ^ { ' ^ -^ ! Y^ ^ 50 i ^ ^ :' ^ . -^ 1 . ^ ^ ^^; ii ^ .I I ^ Il^t 50 , •:1: 'r i t 4 , ! , r ^i .. ^} f ! . ^ f I .. 0 .'^ r l'^ r ' , ` 40 , I r l i ^! ^ ! 1 I , 'r { i ` ^ { ^ ' ^ ^ •+ 4 t ' ! ,.,' , t, ^ '- t• I I i , . .± ., .. i t .. i.l ^ • I , ^ rr Ilri 1 , I I E I r I^ r, ! I t-) ? ^ r i ' 30 1 ^ I h' i III' E. t i 30 1 c . , t- i - i f ln 1 I r r Y j ^ I 1 1 : f t I ' r } r{ 1. '. , , r r ' I {I ' I.1 1! [ rl r 17 { I 20 i 20 -• „ , .} , r: ^,. r {. ^i } III i!I } l,l Stl „ I ff { j^
r I t. {„r t. .I III .y. ( I ' ' .e ,fIY yi ., 10 10
'l^i!li l+}t i„1 I r
J, 5 L a i 5 I. ( ,I r. I rE {^ 4 0 II: I {r ._• . , , 1 .. I I , • r .. : • Vir 4 - m 3 • ! E,., ;. 'Ir I . r , ^': 'r ' 1 1 , I i ' ll^ , f 11 • t f 1' i ' V i ! l ! t' ^ t i I 1 1 i }, ^' I• I ^ { u.,. . ,: , i t ^ 1; .1 ' r r j { ; I : 2
rllt 1 ill I I : , , . ^ I ^ ' ^ r ! E 1 'r { t t r ! !^ t ` i1 ' i ^ , I+ { , .. ! . ' ,. ,•„ I , r i i r^ , ,... j i , 1 t , E 71.,. ;^. -} , I } I , I , •r f , ; ^, r I^t . , if ii I' , if. , t I I r t {' ^ { , .! ...^^ ,. rl 1^},I I{( rlit . r t^ , i ^ ^ r ^. ^.^ ^; i^ V • ;... v^ 1 ^a ► r!-^'t, ^i^., ` L if .{{ q 4 {...... I••r•! i t r tl Mi.. 4 , { t• t} rrt r,"r - ! 7 7 II r 't t"t }1 'Ir ,. rl. I° }^ . a , •• i t ^ r frl r t k r^ I h 1 -E ,,. : •• „1'i °f r 1 ' .f ' ! { Irt) ^ ! I E.!
,f..l,...;;.^:f:". 0 I.u :_:: r.: •:•... ..i..k .. i.._ ...... L.I ..4..is^._._i._,i.:i E1i: liL^. :)..^.:L ..... -. . .1....1 ..._..'t.. t_ :? ' ••^ _ 0, 5
0.1 02 0.3 0.4 0.5 1.0 2 3 4 5 6 7 8 910 20 30 40 50 60 70 80 90100 DURA TION - h
LEGEND 6 • 1 */6 PROBABILITY 5 2% PROBABILITY 4 5% PROBABILITY 3 10% PROBABILITY 2 20% PROBABILITY 1 50% PROBABILITY VICTORIA RD.
RYDALMERE RIVER
HARRIS STREET
SILVERWATER BRIDGE
21x25
GRANVILLE
LEGEND NOTE' LOCATIONS REFERRED TO IN LOWER PARRAMATTA RIVER FLOOD STUDY REPORT SECTION 5•I 0.5 HISTORICAL FLOOD LEVEL 0 0 .5 I kilometre AND REF. No.(APPENDIX C-5) POSITIONS OF OBSERVED SCALE FLOOD LEVELS EXHIBIT 8 BALUSTRADE
R.L. 10.26 10 1000 m3/s
3 - - 791 m /s ------q 4q':4 4•'4.
540 m3/ 6
J W ------!2>^ X3,8 W J 4
.4 1
0 a'. 00 U. mx zc Lw Qa a m aw a wQ w> w a w a J a. 0 00.W0 a a z z z w 0 z°-' x w 0 ' a H0 w 0 N N Z z w of z I- 0Q w Ja 0D J N m 3
NOTES: 1. THE FLOOD PROFILES SHOWN WERE DERIVED FROM THE HYDRAULIC MODEL 'STUDIES DESCRIBED IN THE 1980 REPORT AND SHOWN ON FIGURE A2 (a) OF THAT REPORT.
2. OBSERVED FLOOD LEVELS SHOWN AS FOLLOWS ; 46 1889 LOWER PARRAMATTA RIVER FLOOD STUDY A 1914 25 0 25 50 75 100 A 1956 FLOOD PROFILES AT 1961 HORIZONTAL SCALE (METRES) LENNOX BRIDGE 0 1967 1975 EXHIBIT 9 RECORDED FLOODS LEVEL OF YEAR LEVEL 11.0 HYDRAULIC FEATURES
R.L.1O.26 TOP OF BRIDGE BALUSTRADE 10.0
9.0
8.0 1889 7-9 R.L. 7.5 LOW POINT IN CHURCH ST. 1914 7.3 R.L.7.29 UNDERSIDE OF 7.0 ARCH
1956 6.34
6.0 1967- -- 6.10 1961 5.8
N 0 } 5.0 0 E
R.L.3'29 "SPRINGING" - 1975 -• 3 .20 OF ARCH
2.0 I R.L.1.9 CREST OF 0 0 0 0 W o CHARLES ST. WEIR to to co ti
1.0
NOTE' FOR LOCATION OF RATING CURVE REFER EXHIBIT 9 0.0
LOWER PARRAMATTA RIVER FLOOD STUDY RIVER BED -I.0 200 400 600 Boo 000 1200 RATING CURVES FOR LENNOX BRIDGE DISCHARGE - m3/s EXHIBIT 10 1100 1050 1030 1 1020 1 1000 ADOPTED URBAN RSWM ( 1984) 913 900
BOO 791
710 ME 700 URBAN BAND 610 600 1967
1961 500 1961 '.fODD"' FREDOENCY;AN.ALYSIS 8 -.:L'ENNOX `':Ilk10GE PLOTITED' ROM:OBSERVED FLOODS
RURAL BAND 300
200
100
20 10 5 2 I 0.5%
EXCEEDANCE PROBABILITY - PERCENT
FLOOD ESTIMATES AT LENNOX BRIDGE AND CHARLES ST. WEIR
LEGEND: NOTES:
RSWM (1984) 1. CATCHMENT AREA TO LENNOX BRIDGE IS 104 km2. V SYNTHETIC UNIT HYDROGRAPH (1984) 2- CATCHMENT AREA TO CHARLES ST. FITZGERALD URBAN (1983) WEIR IS 108 km .
+ FITZGERALD RURAL (1983)
RSWM (1980,LENNOX BR.) LOWER PARRAMATTA RIVER FLOOD STUDY 0 R S W M ( 1976) RATIONAL METHOD (1976 & 1984) COMPARISON OF FLOOD Is PROBABILITY CURVES OBSERVED FLOOD, LENNOX BR. (PROBABILITY BASED ON RAINFALL EXHIBIT II EVENT, SHOWING RANGE OF PROBABILITY.) 2501-
EPPING (CHESTER S•T. ) 2001-
EASTW00D
a 100r 0 F EASTWOOD BOWLING CASTLE H14 L CLUBY
CONCORD PLUVIOGRAPH RECORD- RYDE * V, S ILVERWATER DUNDAS ® CONCORD WEST ®'BURWOOD PUBLIC SCHOOL
j-x/PARRAMATTA PARRAMATTA, COUNCIL j LEGEND
WESTMEAD ® 200 GRANVILLE, 0 SUB-CATCHMENT No's LIDCOMBE CREEKS AND RIVERS v,GOLF CLUB CATCHMENT BOUNDARY SUB-CATCHMENT BOUNDARY ISOHYET 24 HOUR RAINFALL6pm-6pm DAILY READ RAIN GAUGE PLUVIOGRAPH STATION USED TO DETERMINE ISOHYETS
PROSPECT DAM
BLACKTOWN 2 3 4 kilometre
SCALE
LOWER PARRAMATTA RIVER FLOOD STUDY CATCHMENT MAP SHOWING STORM ISOHYETS 9th-10th FEBRUARY 1956 EXHIBIT 12 300 RAINFALL SHOWN ON ISOHYETS EPPING (CHESTER ST.) E E CRITICAL BURST
EASTWOOD RYDE BOWLING ---SYDNEY CLUB 2400 1200 2400 1200 2400 17TH 18TH 19TH
CONCOR PLUVIOGRAPH RECORDS
0 CONCORD WEST
0 BURWOOD PUBLIC CHOOL
C. -X/PARRAMATTA /I COUNCIL LEGEND
WESTMEAD GRANVILLE to SUB-CATCHMENT N°'s SEVEN CREEKS AND RIVERS HILLS --• --• - CATCHMENT BOUNDARY SUB-CATCHMENT BOUNDARY /60 ISOHYET 24HOUR RAINFALL 9am-9am 11 DAILY READ RAIN GAUGE PLUVIOGRAPH RYDE STATION USED TO DETERMINE ISOHYETS
PROSPECT DAM GUILDFORD
f BLAOI OWN 2 3 4 kilometre
SCALE
LOWER PARRAMATTA RIVER FLOOD STUDY CATCHMENT MAP SHOWING STORM ISOHYETS 13th NOVEMBER 1961 EXHIBIT 13 100
E CRITICAL E BURST
50
0 TIME 1300 1800 2400 6600 DATE 5TH 6TH
(a) PLUVIOGRAPH RECORDS, 5 -6 MARCH, 1967
IW
100 E E /
50 i^
TIME 1200 1800 2400 0600 1200 DATE 21 ST 22ND
(b) PLUVIOGRAPH RECORDS, 21 - 22 JUNE, 1975
LEGEND, PLUVIOGRAPH STN LOWER PARRAMATTA RIVER FLOOD STUDY 066050 POTTS HILL 066057 RYDE PLUVIOGRAPH RECORDS 067006 FAIRFIELD MARCH 1967 AND JUNE 1975 067006 GUILDFORD EXHIBIT 14 LEER PARRA MATTA RIVER FLOOD STUDY
DIAGRAMMATIC REPRESENTATION OF THE RSW M EXHIBIT 15 NOTE I. REFER EXHIBIT 17 FOR SUB - CATCHMENT DETAILS
LOWER PAR RAMATTA RIVER FLOOD STUDY
REPRESENTATION OF LINKS IN THE RSWM EXHIBIT 16 LEGEND
CREEKS AND RIVERS CATCHMENT BOUNDARY A 10.38 RYDE BRIDGE 1.20 SUB-CATCHMENT BOUNDARY 8400 ISOCHRONE DISCONTINUITY IN ISOCHRONES
A 9 SUB CATCHMENT No. A 70.10 CATCHMENT AREA (ha) S 0 -56 U 84 -00 S 0-33 CATCHMENT SLOPE (%) U 91 00 URBANISATION (%)
0.4y I A 7.20 0' O^ 77 / I o^ ^ ) S 0.90 1 o U 8400
A 12-39 y / I pARRA S 0.20 ^ l U 6000 0.1 ,- 5 02--Y /^
\^-- / A 19.92 S 4.20 U 50-00
A45.15 S 0.15 U 8000 NOTES I. REFER EXHIBIT 16 FOR RSWM A 70.10 LINK DIAGRAM S 0.33 U 9I'000
2 3 4 kilometre
LOWER PARRAMATTA RIVER FLOOD STUDY
CATCHMENT MAP WITH ISOCHRONES EXHIBIT 17 330 385 450
6 1025 1160 1330
2 795 5% PROBABILITY FLOOD (m3/S) 920 2% PROBABILITY FLOOD (m3/S) 1050 1% PROBABILITY FLOOD (m3/ S )
dfi 1.00 - RSWM LINK No. & NODE
NOTES 1. * I% FLOOD AT CHARLES STREET WEIR ADOPTED FROM 'DESIGN FLOODS, SECTION 67. LOWER PAR RAMATTA RIVER FLOOD STUDY 2. PEAK DISCHARGES AT JUNCTIONS ARE SPECIFIED JUST DOWNSTREAM ADOPTED PEAK OF THE JUNCTION. DESIGN FLOWS EXHIBIT IS PROBABILITY - PERCENT i 20 2 5 10 50 100 LEGEND 1-50 FORT DENISON
^ 1X TB I - BOWDEN STREET 1.40 TB 2 - SILVERWATER BRIDGE LINE . 0 TB 3 - Mu ARTHUR STREET BRIDGE i 1.30 EXTRAPOLATION a OF THE M.S.B's ADOPTED DESIGN TIDE CURVE BY THE 1.20 CONSULTANT.
fi 1.10 w CURVE SUPPLIE D 1.00 BY M. S. B w 0 I- 0-90 I L 0 0.80 b
0-01 002 0.05 0•1 0-2 0-5 I 2 5 10 20 50 100 200 0
0 AVERAGE NUMBER OF TIMES RECORDED PER ANNUM
(a) FREQUENCY CURVE OF HIGH 0 TIDES. NOTE : TIDES WERE RECORDED N 0 AT FORT DENISON DURING THE PERIOD w 1916 TO 1945. 0
` 10 00 11 00 12 00 13.00 1400 15 00 1600 1700 18 00 19 00 2000 21 00 2200 23 00 2400 100 200 300
EASTERN SUMMER TIME - 2 February 1983
(b) OBSERVED AND DESIGN TIDES
NOTE = ALL ELEVATIONS HAVE BEEN
LOWER PARRAMATTA RIVER FLOOD STUDY
(c) LOCATION OF TIDE :GAUGES TIDE DtTA FOR (GAUGES SHOWN THUS 0 I LOWER PARF; C ,l.TTA RIVER 0 2 4 6 8
K ILO;'Z-TRZS EXHIBIT I 10.0 LEGEND L. 400 TOP OF DECK A - FLOWED n a 0 - 035, Q - 1050 m/O
90 8 - FLOWED n a 0-035 , Q • 1050 m/9
REFER ukimm ARC! RL7'29 C •• FLOWS n= 0 025 i Q 1050 m/8 FIG. 9
6.0 D - USTFLO n - 0.030, 0 = 1050 m/a E - FLOWED ' n - 0.025, 0 540 m/s - FLOWED n . 0.025 , CH. 1000 -5100 4.0 F 4-0 -A n n 0.025, CH•5100-10160
_.^.-.. .^^ - Vr. y rte .te r-. ^ Q= 540m/a ^_ ... ^ •.+ • - - -• .r --. _^- • G - AS FOR RUN F, F.L. CH. 1000 • R.L. 0.66 2.0 2.0 r ^ ^ "'-^ a s --- HISTORICAL FLOOD LEVEL AND REF. No. ZW J J (APPENDIX C-5) w W ^s W 00 9 N 00 pp rp \ Z Z N tt-
23
---- DISCHAR GE TT -4.0 •4a T --- MANNING
^ z K % 2.0 yy^^ C -6a _ w3 , = S Z I -6.0 m y W „ y. W H a) J Q_ w 4 C W W
8 ^ H 5 1- ^ u I ^, 'a r N m a 9 > ; < W < O -8.0 13 Y ¢ ^ < O % ° g O t l A I W
qq N J
J FT w I ryN ^p ^y -q (^y/ ((yy e ryry [f II < N (^ N N N N N N N m N p N^y NN y m -20 0 to 16 N - ry a N m ( I N t }t N t P f ^1 t O N y - n F IB i $ $ m R q N Q S Q ^) F*: t, I f q °a BED LEVEL i N M O N N tV N N P! lV 01 nl N N N N /1 N tti N N f N 14 N N N lV MI M M N % ERROR
S 8 8 8 (b) EFFECT OF % ^RROR IN DISCHARGE ' CHAINAGE 8 $ I $ $ i 3 a Y & MANNINGS 'n VALUES AT DUCK I L' ij ij ijtiI1i1 i i1 ' i i RIVER CONFLUENCE. LONGITUDINAL SECTION
83 40 '0 i 1 .• DISCHARGE 0 "- MAM$I$6a 'w
L066 6.0
00 R.L000 J J O W,M ^ w R t tat •0 Z a gg S5
-4.0 •0 G 0 Q TTT 7 7 T7 T T 7TT T •0 5-0 / C J W /^ w w > Mj E E E E E E E E E EEEI E E E E '0 J : ?. : I I ^ w 43 -10 0 % ERROR 0: ! i F V I w ^ ^ ° a (c) EFFECT OF % ERROR IN DISCHARGE a MANNINGS n VALUES AT T CHARLES STREET WEIR. ^ If OWER PARRAMATTA RIVER FL000 STUDY
BED LEVEL $ e g e i a v ® s d It a a $ o a v o S e o m v a i e a a d v n d n e p o a LOWER PARRAMATTA RIVER
8 $D PROFILES CHAINAGE 8 8 6 6 $ 8 B 8 8 8 8 TRIAL FLOOD $ e E a^` $ r ^^ LONGITUDINAL SECTION EXHIBIT 20 VERTICAL SCALE (G) FLOOD PROFILES HORIZONTAL SCALE 50- 5. 0 I i
4-0 4-0
30 3-0
20 2.0
1 0
00 00
_10
I f I NOTES v ` I I I. ALL LEVELS ARE TO m. A.H.D. w 2. REFER EX. 23 TO 26 FOR FLOOD i 1 LEVELS AND FLOW DISTRIBUTION J - 3-0 -30
LEGEND
40 LEVEL I % FLOOD LEVEL BED j ^ ! I ^ I 1 ( ^ I 2% FLOOD LEVEL
I i) I ^ i I !I i ! 5% FLOOD LEVEL -_; -^ i^ 111111 I STORM TIDE LEVEL R.L. I.50 ^ ( I= % ^ ( ^ ( i ^ I ^ 1 ' ^ 1 I ^ I -06
s l I 1 ( r 31 ; 1 Zi .w wd I WE ( ! 1 gym, 0 I ^^m
O a Q m m N m N O N N 0 » NI N O N N N O N 0p O N N ! h N N N ry N N N N N NI N N O ryry ly e N N, N m N N N N 1 P! N N hl hl P^ 'f) A 0l 1 N b) ,O) . Oi W^ b hl tl N q t- ,D) h N N - h Pl1 -I M '- Pt nl N h , d r M1 . NI m P1 IA! rI N t`) BED LEVEL P P 7 NI N N N N Q P 7 PI P P PI P' P PI P P P P P 'I PI P QI P < P PI P h Yi 7 h ,o l v I P P P P h ,D h P P P P Yf h I I i 8 8 8 8 8^ 8 8 8 ^^ 8 8 8 8 8 ) 8 8 8 8 8 8 CHAINAGE 81 8 8 ^ 1 8 8 8 8 8 81 8 8 1 8 11 M t_ N 1 8 8 1 V bi NI N, l vl N I 1 h rt M ,ell Mf, N N 1 N N N N NI NN^^ N PS I 6 I hl h h ql fl Yfl hl PI P P ) P P I O ^ P I P ? I P ^ Xf l ) Rl RfC^ppl M 81N 7 7
LONGITUDINAL SECTION HORIZONTAL SCALE 0 1 2 3 4 5mNrn
VERTICAL SCALE
LOWER PARRAMATTA RIVER FLOOD STUDY
LOWER PARRAMATTA RIVER I%,2% AND 5% FLOOD PROFILES CR 1000 - CH. 6100 EXHIBIT 21-I 40 R.L. 990 ROAD LEVEL 9.0 o ^9^ BO z 791 m3h 8.0
T9 ' ND£RS10E OF ARCH R.L. T,29 7-0 Jr ¢W. 540 m3/i - -- - - &0 y gqc• 1 -- _ - B•0
5-0 5.0
. 49 -`--.... ^ ^ ^ ^.. ti 1 . 1. 4.0
3.0
2'0 NOTE S
9 ALL LEVELS ARE TO m. A.N.D. 1.0 2. REFER EX. 23 TO 26 FOR FLOOD LEVELS AND FLOW DISTRIBUTION
00 0.0 w LEGEND J 19 I % FLOOD LEVEL 1 10 2% FLOOD LEVEL 2 ^ BE0 5% FLOOD LEVEL . LEY 2.0 z 0 LEVFO -39 3.0 w JI V w Q w 2 S 39 w
Q Q N N F t-S F $C4 0.4 h; @ N w N tl ° r a N t @ Qr Ntl F C ox C qV^ "59 ¢F y zo ¢ 3 Q2 C z QSC w 4 I r < Q g O i J 3 3 y^I 0.5 U N zm 7? ^ c^ ¢ $x Y^ ?£Z
!7 d O N N N N N N S LEVEL Q N m O N 0 N N N N N ^p ry N 01 P O f f P P !1 f m Q ^p @ m N N - ; - MJ 1• Q N N O m Y q h i! 4 I I 1 CI N - N N - N N N N %1 N p O P P A @ O 9 N (J lV N MI N N N - N 1 1 t j j f NI N N N CI i A j1 I I 500 -- apook- f;iA6E 8 8 8q 8 8 8 $ 8 8 8 8 8 HORIZONTAL SCALE c 8 8 8 q 8 8 8 8 8 8 8 8 8 8 8 8 8 T 1• h /• h rf•. 1- ^. ! p h h N m N N N N m N
I 4 51VAN LONGITUDINAL SECTION VERTICAL SCALE
LOWR PARRAMATTA RIVER FLOOD STUDY LOWER PARRAMATTA RIVER 1 2% AND 5% FLOOD PROFILES CH. 6100 - CR 10180 EXHIBIT 21- 2 4V YV
/{%
- rr
Q 20 20 -.. RI-1-50 ^ R.L. .50 4: ^ + a > 10 w w J w w w
W yj ^ J > z BED a a -20 'n -20 - z m ¢ LEVEL a g CONCRETE LINED a a 3 f ,
BED F n e' N BED N S 4 h q e am LEVEL N N LEVEL ? q 0 ^ ♦ ♦ ^.^ Q 8 CNAINAGE g K441NiWG N N d m " G F N u ® e $ "a 8 01
(b) LONGITUDINAL SECTION (c) LONGITUDINAL SECTION HASLAMS CK. POWELLS CK.
R0xIMA1ED LOCATION OF T -`^"---- r_ BRIDGE UNDERSIDE
5C
NOTES 40- 4 1. ALL LEVELS ARE TO in. A.N.D. 2. REFER EX. 21 & 22 FOR FLOOD LEVELS AND FLOW DISTRIBUTION
LEGEND
W LL I % FLOOD LEVEL w! 2% FLOOD LEVEL tltl Op 5% FLOOD LEVEL p d STORM TIDE LEVEL R.L. 150 iP _ • J IMSTORICAL FLOOD LEVEL AND REF. No. (APPENDIX C-5)
k ! .! i w -2 n
w I LEVEL -3e ^TT-1, 0 500 1000 m HORIZONTAL SCALE -g m n 6 1 2 5 4 5makm n a VERTICAL SCALE z -0 W 13 m m Q= 4 Q Q ¢ ¢ 6 W ¢¢ % W F J
BED LOWER PARRAMATTA RIVER FLOOD STUDY lop l A " og ! LEVEL N ^ 1 P N N 9 N 10 pr O Q Ti i ^ 1 i N N IT I Q y tt Q p 4 DUCK RIVER, HASLAMS CREEK CHAI^A6Eli w ^ B B c : n m n a a a 0 6 $ _ $ In x 8 a PO LS CREEK I%,2% AND 5% FLOOD PROFILES (a) LONGITUDINAL SECTION - DUCK RIVER EXHIBIT 22 RYDALMERE
DUNDAS NORTH MAIN NORTHERN PARRAMATTA RAILWAY BRIDGE
4.50 4.00 2.00 4.10 3.60 1.75 3.75 3.20 I.55
RHODES
CONCORD 3.00 3.50 WEST I 2.78 3.24 2.65 3.08
4.40 4.15 3.85
3.00 2.80 2.60
MAIN WESTERN 3.60 RAILWAY BRIDGE 6.00 3.38 CO Q 1 2 - 5 0 5.75 3.14 2.23 5.58 ,zoo 2-15
NORTH QTOATI
6.40 NOTES 6•I0 5.93 I . REFER TO EXHIBITS 21-I 2, 22 FOR FLOOD PROFILES 2. ALL LEVELS TO m. A.H.D.
BRIDGE PARR AMATTt 5.60 I % FLOOD LEVEL ROAD---'7-l-,', 5.22 2 % FLOOD LEVEL LOWER PARRAMATTA RIVER FLOOD STUDY 4.80 5 % FLOOD LEVEL LOWER PARRAMATTA RIVER AND TRIBUTARIES PLAN OF I%,2%AND 5% DESIGN FLOOD LEVELS EXHIBIT 23 FLOOD LEVEL DETERMINED BY TIDE LEVEL
MEADOWBANK RYDE MAIN NORTHERN RAILWAY BRIDGE MELROSE PARK 8
REFER TO EXHIBITS 21 - I E. 2, 22 FOR FLOOD PROFILES 2. ALL LEVELS TO A.H.D.
3. DRAWING NOT TO SCALE
2 ^S 5c,,//-,,t .{ Gi L, .. ^St rf r-^j:-^^-C_ i S 2 iec 5-1- q-rIPARRAMATT ROAD )C(Q.:1 :q- y.l -/- , LOWER PARRAMATTA RIVER FLOOD STUDY LOWER PARRAMATTA RIVER AND TRIBUTARIES PLAN OF t%, 2%AND 5% DESIGN FLOOD LEVELS EXHIBIT 23 FLOOD LEVEL DETERMINED BY TIDE LEVEL
MAIN NORTHERN NCATH RAILWAY BRIDGE 4A ^.Pl ATTA
CAM ELLIA
MAIN `C WESTERN RAILWAY BRIDBE \
17 I. REFER TO EXHIBITS 21-I B 21-2 AND 22 FOR FLOOD PROFILE. 82 1.5 ?-DRAWING NOT TO SCALE. I 0.2 Z. FLOW VELOCITIES SHOWN REPRESENT AVERAGE VELOCITI ACROSS THE CHANNEL AND OVERBANK AREAS.LOCALISED VELOCITIES AT A PARTICULAR SITE WILL VARY FROM O. 5 THE AVERAGE VELOCITY AND WOULD BE INFLUENCED BY 74 2.3 FACTORS SUCH AS CONSTRICTIONS, OBSTRUCTIONS AND 116 O' 6 RRAMATTL1.1 FLOOD DISTRIBUTION PROXIMITY TO MAIN RIVER FLOW PATH. ROAD 4. SECTIONS VIEWED LOOKING DOWNSTREAM. LEFT BANK LOWER PARRAMATTA RIVER FLOOD STUDY CHANNEL LOWER PARRAMATTA RIVER -RIGHT BANK AND TRIBUTARIES -FLOW VELOCITY (m/s) I%FLOOD DISTRIBUTION -FLOW PERCENTAGE EXHIBIT 24 FLOOD LEVEL DETERMINED BY TIDE LEVEL RYDALMERE
IN NORTHERN NORTH RAILWAY BRIDGE PARRAMATTA
0 100 2.0 0
0
0.2
NORTH STRATHFIELD
NOTES I REFER TO EXHIBITS 21- 1&21-2 AND 22 FOR FLOOD PROFILE. 2 DRAWING NOT TO SCALE. 3 FLOW VELOCITIES SHOWN REPRESENT AVERAGE VELOCITIES 05 ACROSS THE CHANNEL AND OVERBANK AREAS . LOCALISED VELOCITIES AT A PARTICULAR SITE WILL VARY FROM THE 05 RRAMA AVERAGE VELOCITY AND WOULD BE INFLUNCED BY FACTORS ROADS -%^^ FLOOD DISTRIBUTION SUCH AS CONSTRICTIONS , OBSTRUCTIONS AND PROXIMITY - LEFT BANK TO THE MAIN RIVER FLOW PATH. LOWER PARRAMATTA RIVER FLOOD STUDY - CHANNEL 4 SECTIONS VIEWED LOOKING DOWNSTREAM. LOWER PARRAMATTA RIVER -RIGHT BANK AND TRIBUTARIES 2% FLOOD DISTRIBUTI ON FLOW VELOCITY (m/s) EXHIBIT FLOW PERCENTAGE FLOOD LEVEL DETERMINED BY TIDE LEVEL RYDALMERE
NORTH
PARRAMATTA GAD
Y \RLEG WEIR
CLYDE - CAMELLIA, CARLINGFO RHODES RAILWAY BRIDGE
CONCORD WEST
MAIN 'C WESTERN RAILWAY BRIDGE \
NOTES 1. REFER TO EXHIBITS 21-I a 21- 2 AND 22 FOR FLOOD PROFILE, 2. DRAWING NOT TO SCALE. 05 3.FLOW VELOCITIES SHOWN REPRESENT AVERAGE VELOCITES 81J 2.1 BRIDGE ACROSS THE CHANNEL AND OVERBANK AREAS. LOCALISED I2 05 VELOCITIES AT A PARTICULAR SITE WILL VARY FROM FLOOD DISTRIBUTION THE AVERAGE VELOCITY AND WOULD BE INFLUENCED BY - LEFT BANK FACTORS SUCH AS CONSTRICTIONS , OBSTRUCTIONS LOWER PARRAMATTA RIVER FLOOD STUDY - CHANNEL AND PROXIMITY TO THE MAIN RIVER FLOW PATH. LOWER PARRAMATTA RIVER - RIGHT BANK 4.SECTIONS VIEWED LOOKING DOWNSTREAM. AND TRIBUTARIES -FLOW VELOCITY (m/s) 5% FLOOD DI EXHIBIT 126 -FLOW PERCENTAGE