GREAT LAKES COUNCIL
KARUAH RIVER FLOOD STUDY
FINAL REPORT
November 2010 . GREAT LAKES COUNCIL
KARUAH RIVER FLOOD STUDY
FINAL REPORT
November 2010
Prepared By:
PATERSON CONSULTANTS PTY LIMITED 1/45 PRINCE STREET GRAFTON NSW 2460
P O BOX 596 GRAFTON NSW 2460
Tel: (02) 6643 1588 Fax: (02) 6642 7566 E-mail: [email protected]
Version 8
Authorised for Release Copy of . . DOCUMENT CONTROL SHEET
Paterson Consultants Pty Ltd Suite 1, 45 Prince Street P O Box 596 Grafton NSW 2460 Grafton NSW 2460 Telephone: (02) 6643 1588 Job Name: Karuah River Flood Study Facsimile: (02) 6642 7566 Job No.: 07-012 Email: [email protected] Original Date of Issue: August 2007
DOCUMENT DETAILS Title: Karuah River Flood Study Principal Author: K W Paterson Client: Great Lakes Council Client Address: Breese Parade, Forster NSW 2428 Client Contact: Kumar Kuruppu
REVISION / CHECKING HISTORY Version Number Version Name Date Issued By 1 Draft Report – Version 1 August 2007 KWP 2 Draft Report – Version 2 April 2008 KWP 3 Draft Report – Version 3 May 2008 KWP 4 Draft Report – Version 4 September 2008 KWP 5 Exhibition Report July 2009 KWP 6 Exhibition Report November 2009 KWP 7 Exhibition Report February 2010 KWP 8 Final Report November 2010 KWP
DISTRIBUTION RECORD Version Number Destination 1 2 3 4 5 6 7 8 9 Client (bound) 10 Client (electronic) 1 1 1 1 1 1 1 5 DECC (electronic) 1 1 1 1 1
File Copy 1 1 1 1 1 1 Paterson Consultants Library 1 1 Paterson Consultants Pty Limited 3.
TABLE OF CONTENTS PAGE NUMBER
ACKNOWLEDGEMENTS 6
FOREWORD 7
SUMMARY 8
1. INTRODUCTION 15
2. STUDY APPROACH 16
3. AVAILABLE DATA 17
3.1 Overview 17 3.2 Previous Studies, Documents 17 3.3 Government Agency Records 28 3.4 Resident Interviews 32
4. HYDROLOGICAL INVESTIGATION 34
4.1 Overview 34 4.2 Hydrology Model - Karuah River 34 4.3 Design Flood Hydrographs 38 4.4 Estimation of PMF 39 4.5 Flood Frequency Analysis 41 4.6 Comparison of Results 44
5. HYDRODYNAMIC INVESTIGATION 45
5.1 Overview 45 5.2 MIKE-11 Model of the Karuah River 45 5.3 MIKE-11 Model Calibration and Verification 49
6. DESIGN FLOOD LEVELS 55
6.1 Process of Assessment 55 6.2 Design Tailwater Levels 55 6.3 Calculated Design Flood Levels 56
7. SENSITIVITY ANALYSIS 58
8. PRELIMINARY ASSESSMENT OF CLIMATE CHANGE IMPACTS 61
9. PROVISIONAL FLOOD HAZARD AND HYDRAULIC CATEGORY ANALYSIS 63
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TABLE OF CONTENTS (Cont) PAGE NUMBER
REFERENCES 65
GLOSSARY 67
TABLES
0. DWE Gauging Station 18 1. Significant Historical Floods (Station 209003, "Karuah River @ Booral") 19 2. Historical Flood Data – RTA Bridges 20 3. Predicted Peak Discharges – Karuah River (Source: PWD – 1981) 21 4. Recorded Peak Flood Levels (Source: PWD Peak Level Recorders) 22 5. Estimated Peak Flood Discharges – Karuah River at Booral 25 6. Design Water Levels at Karuah (Source: Port Stephens Flood Study, Reference 8) 26 7. Recorded Flood Levels, Hunter District Water Board 28 8 Ranked Flood Sources 1971 to 2007 – Karuah River at Booral 30 9. Relevant Rainfall Stations 32 10. Results of Additional Survey from Resident Survey 33 11. Comparative 4-day Total Rainfalls 36 12. Comparison of Modelled and Recorded Peak Discharge 37 13. Peak Discharges – Design Floods 39 14. PMP Rainfall Estimates (Karuah River at Karuah) 40 15. Peak Discharges - PMF (Source: GSAM Method) 41 16. Peak Flood Discharges - “Karuah River @ Booral” 43 17. Comparison of Peak Flows, Karuah River at Booral 44 18. Localities and Cross-sections – River Distance 46 19. Hydrograph Input Location 49 20. Comparison of Historical Flood Levels 51 21. Comparison of Historical Flood Levels and Design Flood Levels 52 22. Adopted Mannings `n’ Values 54 23. Design Flood Levels at Booral 56
FIGURES
1. Study Locality 2. Study Catchment 3. Rainfall Stations 4. RORB Model Layout 5. Comparison - 1977 & 1978 Floods 6. Comparison - 1990 Floods 7. Comparison - 2001 Flood 8. Comparison - 2007 Flood
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TABLE OF CONTENTS (Cont) PAGE NUMBER
FIGURES (Cont)
9. Flood Frequency - Karuah River at Booral 10. Tributary Inflows - 1% AEP Storm, 36 Hour Duration 11. Karuah River Flows - 1% AEP Storm, 36 Hour Duration 12 Comparison 1% AEP to PMF Flows, Karuah River 13. Location of Cross Sections – Upper 14. Location of Cross Sections – Lower 15. MIKE-11 Model Layout 16. Historical Water Levels – Sheet 1 17. Historical Water Levels – Sheet 2 18. Comparison of Model Results and Booral Rating Curve 19. Historical Flood Profiles, Karuah River – Upper 20. Historical Flood Profiles, Karuah River – Lower 21. Comparison of Flood Levels, Karuah River at Booral 22. Design Tailwater Levels, Karuah 23. Design Flood Profiles, Karuah River – Upper 24. Design Flood Profiles, Karuah River – Lower 25. Design Flood Levels, Karuah River near Karuah 26. Sensitivity Testing, Karuah River – Upper 27. Sensitivity Testing, Karuah River – Lower 28 Diagrammatic Representation, Flood Levels 29 Provisional Flood Hazard 5% AEP - Sheet 1 30 Provisional Flood Hazard 5% AEP - Sheet 2 31 Provisional Flood Hazard 5% AEP - Sheet 3 32 Provisional Flood Hazard 1% AEP - Sheet 1 33 Provisional Flood Hazard 1% AEP - Sheet 2 34 Provisional Flood Hazard 1% AEP - Sheet 3 35 Provisional Flood Hazard 0.5% AEP - Sheet 1 36 Provisional Flood Hazard 0.5% AEP - Sheet 2 37 Provisional Flood Hazard 0.5% AEP - Sheet 3 38 Provisional Flood Hazard PMF - Sheet 1 39 Provisional Flood Hazard PMF - Sheet 2 40 Provisional Flood Hazard PMF - Sheet 3
APPENDICES
A. Annual Flood Series, Station 209003, "Karuah River @ Booral" B. Daily Rainfall and Pluviometer Stations C. Design Rainfalls - Intensity-Frequency-Duration D. Design Flood Levels E. Design Flood Discharges F. Sensitivity Testing - Design Flood Levels
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ACKNOWLEDGEMENTS
This study has been undertaken by Paterson Consultants under the auspices of the Great Lakes Floodplain Risk Management Committee.
The Committee comprises representatives from:
- Elected representatives, Great Lakes Council; - Council officers, Great Lakes Council; - Nominated officers of State Emergency Services, Department of Environment and Climate Change; - Nominated community representatives.
The study has been funded by the NSW State Government and Great Lakes Council on a 2:1 contribution basis under the State assisted floodplain management program.
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FOREWORD
The New South Wales Government's Flood Prone Land Policy is directed at providing solutions to existing flooding problems in developed areas as well as ensuring that new development is compatible with the flood hazard and that it does not create additional flooding problems in other areas.
Under the policy, the management of flood-prone land remains the responsibility of local government. The State Government provides specialist technical advice and financial subsidies for studies and capital works to assist councils in the discharge of their floodplain management responsibilities.
The flood policy provides for technical and financial support by the government through the following four sequential stages:
* Stage 1 - Flood study:
Determines the nature and extent of the flood problem.
* Stage 2 - Floodplain Risk Management Study:
Evaluates management options for the floodplain in respect of both existing and proposed development.
* Stage 3 - Floodplain Risk Management Plan:
Involves formal adoption by council of a plan of management for the floodplain.
* Stage 4 - Implementation of the plan:
Involves construction of flood mitigation works to protect existing development and includes use of local environmental plans to ensure new development is compatible with the flood hazard.
The Karuah River Flood Study constitutes part of the first stage of the management process for the Karuah River from Stroud Road to Karuah. The Karuah River Flood Study has been prepared for Great Lakes Council to determine an appropriate floodplain risk management strategy.
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SUMMARY
The Karuah River Flood Study has been undertaken to provide flood information for establishment of a floodplain risk management planfor the Karuah River. The end use of this study will most likely be for the setting of development controls and addressing flood access issues.
The study area covers the Karuah River from Stroud Road to Karuah.
The study approach adopted involves:
- collection and assessment of flood data from government resources and resident interviews;
- definition of waterway areas along the Karuah River by ground survey;
- establishment and calibration of an hydrologic model and a riverine hydraulic modelto predict design flood levels for the 0.5, 1, 2, 5, 10 and 20% AEP floods and the Probable Maximum Flood (PMF);
- presentation of design flood information as:
- flood profiles for each of the design events;
- tabulated values for each of the flood contours;
- flood contours over cadastral maps for three of the seven design floods investigated.
Available data on flooding comprises:
- recorded flood flows; - recorded rainfalls; - recorded flood levels.
Available flood information data comprises:
- previous studies and documents held by various government instrumentalities and Great Lakes Council;
- flood data derived from site inspection and resident questionnaires.
The DWE published flood data (through the “PINNEENA” CD) indicates the only relevant hydrographic station is Station 209003 “Karuah River at Booral”, which was established in 1968.
The top 6 ranked floods at Booral recorded at Station 209003 were 1971, 1985, 1990, 2007, 1978 and 2001 with peak levels between RL 10.35 m AHD and 8.92 m AHD.
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The RTA bridge drawings for the Karuah River at the Stroud – Dungog Road (the “Washpool”) and the Karuah River at Booral quote historical flood levels. At Washpool, the levels quoted are RL 38.5 m AHD and RL 37.1 m AHD for 1850 and 1946 floods, while at Booral, the level quoted is RL 11.78 m AHD for the 1946 flood.
Calculation files from the PWD, Hunter District Office, circa 1981:
- identify hydrological analysis for the Karuah River leading to peak flood discharge estimates for 10% AEP, 5% AEP, 2% AEP and 1% AEP floods at Booral and Karuah;
- list a series of peak level indicators from Hunter District Water Board reports on the 1976, 1977 and 1978 floods.
Great Lakes Council and Port Stephens Council have been undertaking floodplain management studies for the foreshores of Port Stephens. The Port Stephens Flood Study (Reference 8) provides analysis of water levels in Port Stephens and some hydrological analysis of the Karuah River catchment. The Port Stephens study has been used to set prevailing water levels at Karuah for this study, while the hydrologicalanalysis is of limited value due to its concentration on rainfall events of days (for determination offlood water levels in Port Stephens) as opposed to this study, where rainfalls of 24 to 48 hours are significant.
The Hunter District Water Board produced reports on the 1976, 1977 and 1978 floods with peak levels recorded between Washpool and Allworth. These reports produce the only flood levels along the Karuah River for a single event, noting that the 1978 flood was the highest of the 1976, 1977 and 1978 series, but it only ranks as fifth on the 1968 to 2001 series at Booral.
The Department of Water Resources produced a flood study for Stroud quoting the largest flood in Stroud as occurring in 1956. Examination of the recorded flood levels in Stroud suggest that in floods up to the historically recorded events, Stroud will be above the Karuah River flood levels and thus, Karuah flood levels are likely to have limited impact on Stroud.
The DWE hydrography branch has gauged flows for the Karuah River at Booral, up to about two thirds of the bank full height. The rating table for Booral has been examined and accepted up to the bank full level (about RL 11.0 to 11.5 m AHD).
The Bureau of Meteorology has limited data in rainfall within the study catchment. The data comprises of two operational daily rainfall stations in the catchment, while the nearest pluviometers are located near Williamtown and at Chichester Dam.
An initial contact with the residents of the riverine corridor through the study area was initiated by questionnaire. Three hundred and sixty seven (367) questionnaires were issued to property owners. Sixty eight (68) responses were received. Fifty five (55) responses indicated “no information on flooding available” and within the remaining thirteen (13) responses, no flood data was identified that justified the cost of ground survey to collect the data.
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A “doorknock” program identified 13 additional marks, representing either 2007 flood peaks or “highest recorded flood” based on oral history.
The total catchment of the Karuah River at Karuah is 1456 sq kilometres, while the Karuah River catchments downstream of Stroud Road and at Booral are 733 and 974 sq kilometres respectively.
An hydrological model of the Karuah River catchment has been established, using RORB software, to provide hydrograph inputs to a hydrodynamic model.
The RORB model was initially calibrated and verified against the 1978, 1990 and 2001 floods. These floods (ranked 5th, 2nd and 6th highest at Booral) were selected as having reasonable rainfall data across the catchment and recorded hydrograph data at Booral). Other floods (1971 and 1985) were not used because of missing data.
Initial work on the hydrodynamic model indicated discrepancies in some of the historical flood data, while work on the RORB model indicated that the Karuah River catchment was very sensitive to inherent assumptions regarding total rainfall, rainfall patterns and losses (the difference between total rainfall and flood runoff).
Accordingly, additional effort was invested in examination of the 1977 and 2007 floods.
The calibration of the RORB model (by comparison of calculated flows for the Karuah at Booral versus recorded flows) is considered satisfactory and the model parameters derived from the 1977, 1978, 1990, 2001 and 2007 floods were considered suitable to use to predict “design floods”.
The design floods were derived by testing various duration temporal patterns. This testing showed the 36 hour storm to be “critical” (that is, the storm that produced the highest peak discharge).
RORB model parameters used were as follows:
- Parameter kc: 65
- Parameter n: 0.8
- Loss model: Initial/continuing losses: - Initial loss: 25 millimetres - Continuing loss: 2.5 millimetres per hour
- Areal reduction factor: 0.9
Design floods were derived from the RORB model using rainfall derived from Australian Rainfall and Runoff for floods varying between 50% AEP to 0.2% AEP and included the 1% AEP event.
For comparative purposes, the estimated 1% peak flood discharges for the Karuah River at Booral and Karuah were 3,313 cu m/sec and 4,060 cu m/sec respectively.
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The Probable Maximum Flood (PMF) was derived using Probable Maximum Precipitation (PMP) and the calibrated RORB model. The PMP analysis was based on the three separate methods published by the Bureau of Meteorology (namely, Generalised Short Duration Method (GSDM), Generalised Tropical Storm Method (GTSM) and Generalised South East Australia Method (GSAM)).
The peak PMF discharges for the Karuah River at Booral and Karuah are 9700 cu m/sec and 12,710 cu m/sec respectively.
The “critical” duration for the PMP storm lies between the 12 hour and 24 hour duration. Given the results of this study are to be used for emergency planning purposes, the 24 hour storm has been adopted for prediction of the PMF flood hydrographs.
Flood frequency analysis of the annual peak flood discharges for the Karuah at Booralhas been undertaken. Regrettably, it is the only hydrographic station in the study area and has only 38 years of record available.
Flood frequency analysis using LP3 and GEV frequency distributions give 1% AEP peak discharges at Booral of 3220 cu m/sec and 2710 cu m/sec respectively.
The comparison between the design peak flows produced by the RORB model and the historicallyrecorded events is reasonable and consequently, the RORB model has been used to produce design inflow hydrographs for the hydrodynamic model.
An hydrodynamic model of the Karuah River from Stroud Road to Karuah was established using MIKE-11 software. The total river length of the model is some 47.03 kilometres. The model comprises:
- a single river to represent the Karuah River;
- seven notional looped branches to represent the bridge crossings at Stroud Rail (railway bridge), Washpool and Booral;
- the low level road bridges at Stroud Road and Stroud have not been modelled as they will be “drowned out” in major floods;
- tributary hydrograph inputs (from the RORB model) at eight points;
- a single tailwater control at Karuah based on flood levels prevailing in Port Stephens.
The data available for model calibration and verification is limited and comprises:
- four recorded flood levels along the Karuah River for the 1977 and 1978 floods and five recorded flood levels in the 2007 flood;
- flood levels and discharge rating for Station 209003 “Karuah River at Booral” over the period 1969 to current;
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- historical “highest flood levels” recorded on bridge drawings and derived fromresident interviews (oral history).
The hydrodynamic model parameters (principally Mannings `n’ values) derived by:
- reproduction of the rating curve for Station 209003 using the 1990 flood;
- testing against the record longitudinal profiles of the 1977, 1978 and 2007 floods;
- checking the design 1% AEP flood levels against the historicallyrecorded flood events.
In testing for the historical flood events (1977, 1978, 1990, 2001 and 2007), tailwater levels in Port Stephens were derived from actual measurements (2001 and 2007) or tidal predictions over the relevant dates (1977, 1978 and 1990).
Considerable investigation was made into differences between modelled flood levels and HDWB peak level indicators. After testing, the conclusion drawn was that there were some booking or transposition errors in the HDWB data.
The calibration and verification of both the RORB hydrology model and the MIKE-11 hydraulic modelare considered adequate for prediction of design flood levels for floodplain management along the Karuah River.
As noted earlier, the design flood hydrograph inputs for the various design floods (between 50% AEP and 0.5% AEP and the PMF event) were derived from the RORB model.
Three scenarios of prevailing ocean level have been examined to apply for Port Stephens at Karuah. These three scenarios were:
- Current conditions combining the current design floods with a 0.9 metre tidal range (for all design floods);
- Current conditions applying a 10% AEP flood to a 1% AEP ocean level which recognises historically recorded storm surges but that there is not a direct relationship between river flooding and ocean surges;
- A climate change induced increase in ocean level of 0.8 metres (as indicated by the IPCC Fourth Assessment Report) with current design floods.
The design floods developed were the 50%, 20%, 10%, 5%, 2%, 1% and 0.5% AEP events plus the Probable Maximum Flood (PMF). The design flood results are tabulated in Appendices D and E.
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Sensitivity testing of the design floods has been undertaken for:
- increases of 20 percent in flood discharges or river friction for comparison against an adopted base case (1% AEP flood);
- various water level scenarios in Port Stephens ranging from a 0.9 m AHD maximum tidal level to an RL 1.5 m AHD 1% ocean level plus allowance for a 0.8 m climate change induced increase in mean sea level.
The design 1% AEP flood levels vary through the study area as follows:
- Stroud Road: 41.3 m AHD; - Stroud (confluence of Mill Creek): 25.67 m AHD; - Booral: 11.48 m AHD; - Allworth: 4.56 m AHD; - Karuah: 1.5 m AHD (dominated by ocean flooding).
Figure 28 illustrates a diagrammatic representation of the comparison of flood levels and ground levels for the Karuah River near Stroud.
Changes to the assumption regarding timing of the river flood compared to the tidal cycle affect flood levels from Karuah to the confluence of The Branch with the Karuah River. Ocean flooding dominates the design flood levels over the last three kilometres of the Karuah River to Karuah. A climate change induced increase in ocean water level will increase design flood levels below Allworth. The variation of design flood levels for the climate change scenario increases moving downstream of Allworth and varies from 0.1 metres at Allworth to 0.8 metres at Karuah.
A preliminary assessment of climate change induced changes to flood behaviour has been undertaken.
If the predicted climate change induced rise in sea levels occurs, the Karuah River flood levels will be increased between Allworth and Karuah.
Potential changes to rainfall and runoff are less predictable than changes in ocean water levels.
Flood levels along the Karuah River above Allworth are principally controlled by flood peak discharge and friction, rather than flood storage. Thus, various increases for design rainfalls willincrease flood discharges and hence flood levels. Guidance on the impact of various increases in flood discharges is given in the sensitivity analysis.
Flood hazard diagrams through the study area for the 5% AEP, 1% AEP and 0.5% AEP floods plus the PMF flood have been prepared and appear as Figures 29 to 40 inclusive. The flood hazard diagrams divide the inundated area into floodways and flood storage regions. The floodways and flood storage regions are each sub-divided into “low”, “medium”, and “high hazard” using the criteria specified in the NSW Floodplain Development Manual.
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The bulk of the inundated areas along the Karuah River (either floodway or flood storage) are classed as “high hazard”. Areas of “low” and “medium hazard” are quite small in the total inundated area. A third category, “flood fringe” was examined. The criterion for definition of “flood fringe” adopted (for the purposes of this study) was that flood inundation depths were less than 0.2 metres. Analysis of “flood fringe” areas through the study area, using the 10 metre squares prepared to define ground levels, showed “flood fringe” areas as virtually non-existent. Consequently, the flood hazard mapping does not attempt to indicate “flood fringe” regions.
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1. INTRODUCTION
This report presents the results of the Karuah River Flood Study.
Great Lakes Council, through its local land use and management activities in its area of administration is following the Floodplain Management Process, as outlined in the Foreword and promoted by the NSW Government.
The locality of the study area for the Karuah Flood Study is illustrated in a state wide context, and within the context of the villages of Stroud Road, Stroud, Booral, Allworth and Karuah, on Figure 1.
Specifically, the Flood Study covers the Karuah River from a point some 1100 metres upstream of Stroud Road to the old Pacific Highway bridge at Karuah.
A measure of the size of the Karuah River is its catchment area to various locations, as follows:
- Karuah River, immediately upstream of Stroud Road: 338 sq km; - Karuah River, immediately downstream of Stroud Road: 735 sq km; - Karuah River, at Booral: 974 sq km; - Karuah River, at Karuah: 1,457 sq km.
The significant increase in catchment area in the Karuah, immediately upstream and downstream of Stroud Road, follows the confluences of Karuah River with Mammy Johnsons River (315 sq kilometres) and Ram Station Creek (85 sq kilometres).
The study approach is detailed in Chapter 2, while the subsequent chapters detail:
- available background information; - data collection; - hydrological investigations; - riverine investigations; - design flood data; - conclusions.
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2. STUDY APPROACH
The end use of the Karuah River Flood Study is likely to be:
- setting of site specific development controls along the Karuah River in the study area;
- setting of floor levels through the Floodplain Management Risk Plan and development controls along the Karuah River in the study area;
- provide downstream flood levels for future flood studies of the villages of Stroud and Stroud Road.
A reconnaissance survey of the site and the available data suggests that sufficient hydrological data and recorded flood levels will be available to establish and calibrate a hydrological model of the catchment (to estimate flood flows) and to establish a riverine model to define flood levels and flood hazard for a variety of design flood events.
Thus, an appropriate study approach, consistent with the above uses and the constraints outlined in Chapter 1, Introduction, and above, was identified as:
- collection of local flood information by resident interview;
- collection of recent flood records held by government sources;
- collection of ground survey to identify river waterway areas;
- use of the hydrology model for the Karuah River to define flood flows;
- development of a riverine hydraulic model for the Karuah River (through the study area), to define the design flood profiles;
- preparation of design flood profiles for the five design events, namely, 0.5% AEP, 1% AEP, 2% AEP, 5% AEP, 10% AEP, 20% AEP and 50% AEP floods plus the Probable Maximum Flood (PMF);
- presentation of design floods as flood surface contours on a cadastral base.
The lower parts of the study area (from Allworth to Karuah) are tidal. Thus, flooding can be created by riverine flooding or ocean induced flooding or a combination of both.
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3. AVAILABLE DATA
3.1 Overview
The principal data required for a flood study comprises:
- recorded flood levels; - recorded flood flows; - rainfalls; - topographic data information.
Historical rainfall data is available through the Bureau of Meteorology, comprising:
- daily read rain gauges;
- continuous rainfall versus time recorders (Pluviometers which either store the data on site or transfer the data to a central point using radio technology ("ALERT").
Historical flood data is available through:
- previous studies and documents; - information on records held by various government agencies; - resident interviews.
Design rainfall information (that is rainfall-intensity-duration data for various return period storms) is commonly derived from Australian Rainfall and Runoff (Ref. 1). This practice has been followed in this study
3.2 Previous Studies, Documents
There are a limited number of historical documents that have been examined, principally for recorded data on:
- rainfall information; - flood level information; - flood flow estimation; and - general flood information.
The documents examined comprise:
- published reports from government agencies; - published reports from Great Lakes Council; - Roads and Traffic Authority bridge replacement drawings; - Main Northern Railway Line bridge drawings.
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In the review, it was presumed that the published information can be treated as "reliable" and further background work into the published data has not been undertaken. The most important documents are outlined below.
"PINNEENA, Version 9", Department of Infrastructure, Planning and Natural Resources, 2006 (Ref. 2)
DIPNR (now DWE) has published available New South Wales flows records on CD through a series of editions of PINNEENA.
It should be noted that PINNEENA generally contains the digitally recorded information. There is additional historical flood level information held on the original gauge reader cards that does not appear in PINNEENA.
The most relevant DWE station (previously WRC, DWR and DNR) is Station 209003 “Karuah River at Booral”, which has operated since 1968. The other stations in the study area, namely Station 209004 “Mammy Johnsons River” and Station 209008, “Karuah River at Stroud Road” only operated over the period 1968 to 1980/81 and thus only provide a short period of record.
The full list of gauging stations appears in Table 0 below.
Table 0
DWE Gauging Station
NUMBER NAME CATCHMENT START DATE FINISH DATE AREA (SQ KM) 209001 Karuah River at 203 1945 1981 Monkerai 209002 Mammy Johnsons 156 1967 Current River at Pikes Crossing 209003 Karuah River at 974 1968 Current Booral 209004 Mammy Johnsons 318 1968 1981 at River at Stroud Road 209008 Karuah River at 342 1969 1980 Stroud Road 209018 Karuah River at 300 1979 Current Dam Site
The ranking of five largest historical floods recorded at Station 209003 “Karuah River at Booral” is given in Table 1 below, whilst the full flood series is given in Appendix A. The data in Table 1 and Appendix A is derived from a combination of PINNEENA and DWE Hydrography Branch records.
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Table 1
Significant Historical Floods (Station 209003, "Karuah River @ Booral") (Source: Pinneena Version 9)
Rank Flood Year Peak Flow Peak Level (cu. m/sec) (m AHD)
1 1971 2,420 10.35 2 1985 2.090 9.91 3 1990 1,890 9.65 4 2007 1,750 9.47 5 1978 1,510 9.03 6 2001 1,410 8.92
There have been some 208 flow gaugings at Booral. The bulk of these gaugings are low flow measurements at gauge heights of less than 1 metre.
The highest gaugings appear to be:
- 1974 at gauge heights of 5.35 metres, 4.5 metres and 3.78 metres; - 1977 at gauge heights of 3.50 metres and 6.06 metres (float gauging); - 1990 at gauge height of 3.25 metres.
Thus, the maximum gauging is at about half the channel depth (at Gauge height 6.06 m) more than 3 metres below the peak gauge height of 9.30 m recorded for 1971.
RTA Records
The Roads and Traffic Authority have four major bridges in the study area. These are:
- Karuah River at Washpool (Stroud – Dungog Road near Stroud Road); - Karuah River at Booral; - Karuah River at the Karuah Bypass; - Karuah River at Karuah (Pacific Highway).
The “general arrangements” drawings of each bridge were obtained. The bridge drawings for the Pacific Highway and Karuah Bypass contained no flood information. However, the drawings for Booral and Washpool bridges do contain some historical data. This historical data is tabulated in Table 2 below.
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Table 2
Historical Flood Data – RTA Bridges
Item Karuah River @ Karuah River @ Booral Washpool Drawing Date 1980 1944 Datum m, AHD Ft, assumed m, AHD Deck Level RL 39.56 RL 101 ft 14.28 Flood Level: 1850 RL 38.5 - Flood Level: 1894 - 92 ft 11.78 Flood Level: 1946 RL 37.1
Untitled Calculation Folder, Karuah River, PWD Hunter District Office, Circa 1981
The Calculation folder contains several sets of data and calculations for the Karuah River. Specific items of interest relate to:
- estimation of 5%, 2%, and 1% AEP flood discharges for the Karuah River at Booral and Karuah using the Cordrey-Webb unit hydrograph (Reference 5).
- Estimation of flood volumes for the Karuah River at Booral for the January 1976, March 1977 and March 1978 floods as 62.4, 98.3, and 116 Gigalitres respectively;
- Reduction of pluviographs for January 1976 for Chichester Dam, Upper Johnstons Creek and Karuah Forest;
- Reduction of pluviographs for March 1977 for Monkerai and Karuah Forest;
- Reduction of pluviographs for March 1978 event for Chichester Dam, Upper Johnstons Creek, Monkerai and Karuah Forest;
- Estimation of catchment average rainfall (using daily rainfalls from available stations using Theisen polygons) as:
o Period 20 to 25 January 1976: 153 millimetres o Period 1 to 4 March 1977: 190.95 millimetres o Period 17 to 21 March 1978: 332.74 millimetres
- Flood profile for the 1977 and 1978 floods along the Karuah River derived from HDWB peak level recorders;
- Location details for the DWR recorder station at Station 209003, “Karuah River at Booral”
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In the review of the calculation file, it has been assumed that the calculations are arithmeticallycorrect. The peak discharges were derived using 12, 18 and 24 hour design storms from Australian Rainfall & Runoff, ARR – 1977 edition, (Reference 6). The temporal patterns were applied with a zero initial loss and a 2.5 mm per hour continuing loss. The peak discharges were obtained using the 12 hour design storm.
In general, it is interesting to note that the PWD calculation file contains enough information to derive a unit hydrograph for the Karuah at Booral, yet relies on a synthetic unit hydrograph to determine design discharges for the Karuah River at Booral.
It should be noted that Australian Rainfall and Runoff, 1988 (Ref. 1) is substantially different fromthe 1977 edition (Ref. 6).
The predicted peak flood discharges are listed in Table 3 below.
Table 3
Calculated Peak Discharges – Karuah River (Source: PWD Calculation File-1981, using AR&R, 1977 edition)
Frequency Karuah River @ Booral Karuah River @ Karuah (% AEP) (cu m/sec) (cu m/sec)
10 2000 2,458 5 2,462 3,083 2 2,910 3,718 1 3,313 4,270
The calculation folder also lists records from a series of peak level recorders installed by Hunter District Water Board (HDWB) along the Karuah River.
The peak flood levels along the Karuah from the HDWB peak level recorders are listed in Table 4 below. The precise location of the peak level recorders is unknown.
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Table 4
Recorded Peak Flood Levels (Source: PWD Calculation File (1981))
Location River Peak Flood Level Distance (m AHD) (m) March 1977 March 1978
Karuah River at: - Washpool Bridge 5,918 33.86 37.75
- Stroud Bridge 12,478 24.04 25.10 - Stroud to Booral 17,402 15.06 16.44 - Booral 21,948 8.43 9.26 - Allworth Weir 25,512 4.93 5.87 - Allworth 31,741 1.64 No record
With respect to Table 4 above, it is noted that there is a 0.23 m discrepancy between the calculation file (9.26 m AHD) and the DWR record (RL 9.03 m AHD) for the March 1978 peak at Booral.
A smaller discrepancy was noted in the March 1977 flood, where the PWD file gives a flood peak of RL 8.43 m AHD, while the DWR record gives a peak of RL 8.38 m AHD. These discrepancies indicate either the record may have an incorrect connection to Australian Height Datum or involve an incorrect reading.
Stroud Flood Study, WRC, 1986 (Reference 7)
This report covers a flood study of Stroud undertaken by the then Water Resources Commission. The report investigation commenced in 1979, though the report was not completed until 1986.
Major floods were reported in Stroud as occurring in 1913, 1927, 1946, 1956 and 1985. The largest was reportedly the 1956 event. The study reduced available flood marks to Australian Height Datum. The range of surveyed levels was:
- 1956 flood: RL 27.0 m AHD to RL 31.5 m AHD; - 1985 flood: RL 25.2 m AHD to RL 31.8 m AHD.
The locations of the recorded flood levels are shown in the report (Reference 7).
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The two principal water courses through Stroud are Lamans Creek and Mill Creek. These creeks join the Karuah River some 1100 metres downstream of Stroud and some 1500 metres downstreamofthe low level crossing of the Karuah River near Stroud.
Comparison of the recorded 1985 levels in Stroud and estimated 1985 flood levels in the Karuah River, at the confluence of the Karuah River and Mill Creek, show the lowest recorded flood level in Stroud to be about two metres above the Karuah River levels. This implies that Stroud is not affected by Karuah River floods up to the 1956 flood level, but it may be affected in more extreme events.
Port Stephens Floodplain Management Studies (1997 to current date)
Great Lakes Council and Port Stephens Council are progressively undertaking floodplain management for the Port Stephens foreshore areas.
To date, three reports have been produced, namely:
- “Port Stephens Flood Study, Design Water Levels and Wave Climate” (Reference 8) - “Port Stephens Flood Study – Stage 3, Foreshore Flooding” (Reference 9) - “Port Stephens Foreshore (Floodplain) Management Study” (Reference 10)
The first report above contains information relevant to the current study, which is outlined below. The last two reports deal principally with wind driven waves along the Port Stephens foreshores and do not contain information considered relevant to the Karuah Flood Study.
The Port Stephens Flood Study (Reference 8, the first report above) considered flooding in Port Stephens comprising:
- runoff from the catchments of the Karuah River, Myall River, Tilligerry Creek and a number of small catchments;
- ocean water levels at the entrance to Port Stephens;
- local wind set up of waves across Port Stephens.
Some care is required using the report, as water levels are variously quoted to Australian Height Datum (approximately Mean Sea Level) and Indian Springs Low Water (some 0.925 metres below Mean Sea Level).
The principal items of interest to the current study involve:
- estimation of flood hydrographs entering Port Stephens from the Karuah River;
- estimation of peak water levels at the Karuah River outfall into Port Stephens at Karuah. These peak water levels comprised components of flood inflows, wind wave set-up and ocean levels controlling the entrance of Port Stephens.
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With regard to the hydrology of the Karuah River, the study:
- established an hydrologic model of the Karuah River to Karuah (Port Stephens) using the WBNM software package;
- calibrated the WBNM model against floods recorded in January1971 and March 1978.
The WBNM model comprised 53 sub-catchments to detail the 1456 sq kilometre catchment to Karuah.
For the calibration events, pluviometer data was used from Upper Chichester and Williamtown and supplemented with daily rainfall data from Craven, Stroud and Tahlee. The DNR station, “Karuah River at Booral” (Station 209003) was used to determine flood volumes, while the more upstream station, “Karuah River at Monkerai” (Station 209001) was used to assist in determination of initial losses and flood timing.
The model calibration used an Initial Loss – Continuing Loss concept to convert rainfall to surface runoff. The adopted values were:
- January 1971: Initial Loss: 72 millimetres Continuing Loss: 0.5 millimetres per hour
- March 1978: Initial Loss: 120 millimetres Continuing Loss: 1.22 millimetres per hour
The WBNM model parameters adopted were:
- Parameter C = 2.3 (as opposed to the generally accepted value of 1.8) - Non Linearity C = -0.23
The design rainfalls used to derive design flood hydrographs were developed on the basis of mean catchment rainfalls derived from the daily rainfall stations. Thus, the rainfall durations derived were for durations of 1 to 10 days in daily increments.
Similarly, the Study used derived temporal patterns for one to five days in daily increments.
Design hydrographs were derived by testing of each storm, which identified the 5 day storm as “critical”. Rainfall losses were set at 0.0 millimetres and 5 millimetres per hour for Initial Loss and Continuing Loss respectively.
The long “critical” storm duration was justified in the report as being representative of the calibration events, notwithstanding the calibration events identified Initial Losses as high as 225 millimetres.
The report also reports a DWR flood frequency analysis for the Karuah River at Booral for the period 1967 to 1980.
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Table 5 below provides a comparison between the peak flow estimates derived fromthe WBNM modeland the DWR flood frequency at Booral.
Table 5
Estimated Peak Flood Discharges – Karuah River at Booral (Source: Port Stephens Flood Study, Reference 8)
Frequency Return Peak Discharge (% AEP) Period (cu m/sec) (yrs ARI) DWR Flood WBNM Frequency
2 50 705 395 1 5 20 1329 735 1 10 10 1745 1030 1 20 5 2135 1330 50 2 2580 1 1870 100 1 3036 1 2253 Extreme 4000
Notes: 1. Derived extrapolation of Figure 4.10, Reference 8
With respect to Table 5, it should be noted that, whilst the DWR flood frequency represents the historical flood frequency (over the period of available record at that time), the WBNM results are a long duration event, presumably as “critical” for Port Stephens rather than the Karuah River at Booral.
The Port Stephens Flood Study established a two dimensional hydrodynamic model of Port Stephens using MIKE-21 software. This model was used to estimate design peak water levels at Karuah as a combination of flood levels, wind and wave action.
The predicted design water levels at Karuah River are tabulated in Table 6 below.
The report (Ref. 8, Table 6.1 and Figure 6.1) quotes design ocean water levels at the entrance for Port Stephens, comprising astronomical tide plus storm surge as:
- 5% AEP occurrence: RL 1.43 m AHD - 2% AEP occurrence: RL 1.47 m AHD - 1% AEP occurrence: RL 1.50 m AHD
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The above values have been transferred to Table 6 as “peak ocean levels” at Karuah.
It is understood (DECC personal communication) that the components of the various peak ocean levels above comprise:
- Mean Sea Level: RL 0.0 m AHD - Astronomical tide: 0.9 m AHD - Storm Surge: varying between 0.6 m for 1% AEP event to 0.33 m for 5% AEP event.
It should be noted that ocean waves are not expected to break at the entrance to Port Stephens, thus, there will be minimal wave set-up at the entrance.
The design ocean levels (in Table 6) at Port Stephens were derived by combining the astronomicaltide with storm surge values derived from historical storms.
It should be noted that the values quoted in Table 6 represent a concurrent occurrence between the peak of the design 5 day hydrograph in the Karuah River and the peak of the astronomical tide. The report also notes that the 3 day hydrograph created a peak level that was only 30 millimetres lower than the 120 hour storm.
Similarly, the report (Table 11.1, Reference 8) notes that the Karuah River at Karuah is not subject to ocean wave action.
Table 6
Design Water Levels at Port Stephens at Karuah (Source: Port Stephens Flood Study, Reference 8)
Design Water Level at Karuah (m AHD) 5% AEP 2% AEP 1% AEP Extreme
Water Level (no wave action ) 1 1.57 1.60 1.66 NA
Water Level (no wave action) 4 1.76 1.83 1.91 1.97 Water Level (storm tide flood + 2 wind + set-up) 1.76 1.83 1.91 1.97 Peak Ocean Levels3 (normal tide) 1.43 1.47 1.50 -
Notes: 1. Source Tables J6 to J9, Reference 8 2. Source Table 8.1, Reference 8 3. Source Table 6.1, Reference 8 4. Source Table S1, Reference 8
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In summary of the Port Stephens Flood Study, it is noted that:
- the design rainfalls for the Karuah River analysis were based on one to ten day events rather than the more usual practice of application of design rainfalls from AR&R (Reference 1) and application of an areal reduction factor (Section 2.7, Reference 1);
- the study used a long duration storm as “critical”, given this was similar to the calibration events, yet used low initial loss values (derived from AR&R) as opposed to the large initial losses identified in the calibration events;
- The study was directed to prediction of flood levels in Port Stephens, which, because of the size of its catchment, will respond to rainfall over days rather than 24 hours or less. The Study focus will thus concentrate on the long duration events rather than the short duration events that will be “critical” on the Karuah River itself.
- it is surprising that the Flood Study (dated 1996) relied on the frequency analysis at Booral only over the period 1967 to 1980, notwithstanding that flood data for the period 1967 to 1996 should have been available;
- it is also surprising that the Flood Study did not reference the 1985 flood, which was approximately 1 metre higher than the 1978 flood at Booral.
NSW Railways
The North Coast Railway, which crosses the Karuah River at Stroud Road, was constructed in the early 1900’s.
The “Working Plans” for the railway (the design plans) quote recorded flood levels at:
- the Karuah River at Stroud Road: 230 ft (about 40.3 m AHD); - Ram Station Creek (1300 metres south of the Karuah River): 212.42 ft (about 35.0 m AHD)
The “Working Plans” are dated 1909, and thus the recorded flood levels probably relate to floods in the 1890’s.
Hunter District Water Board
The Hunter District Water Board (the predecessor of Hunter Water) investigated drawing water supplies from the Williams River (at Seaham Weir) and from the Karuah River near Booral. As part of those investigations, flood reports were produced for the January 1976, March 1977 and March 1978 floods (References 15,16 and 17).
These floods peaked at Booral at 6.32 m AHD, 7.86 m AHD and 8.38 m AHD, as recorded by the DWR records.
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The reports tabulate a series of peak levels reached for the above floods. The reports identify the flood levels as derived from peak level recorders. The flood levels reported are reproduced in Table 7 below.
The location of the peak level recorders is not precisely identified other than by plotting on an approximately 1:50 000 scale plan. The Hunter Water records indicate some survey was undertaken with the installation of the peak level indicators. However, no records of the original flood readings or surveys (such as level books) have been found.
Table 7
Recorded Flood Levels – Hunter District Water Board
HDWB Peak Level (m AHD) Location Identification January 1976 March 1977 March 1978 Karuah River, 1. No Reading 33.86 37.75 Washpool Bridge 2. Karuah River, Stroud 22.15 24.04 25.10 Karuah River, Stroud 3. 12.93 15.06 16.44 to Booral 4. Karuah River, Booral 6.32 8.43 9.26 Karuah River, 5. 3.02 4.93 5.87 Allworth Weir Site
It is clear that the above HDWB reports are the original source of the data in the PWD calculation files (as reproduced in Table 4).
3.3 Government Agency Records
The government agencies holding records relevant to this study are:
- NSW Department of Environment, Climate Change and Water; and - Federal Bureau of Meteorology.
The records and data accessed are outlined below.
DWE Records, Hydrography Branch
DWE (and its predecessors WC&IC, WRC, DWR, DLWC and DIPNR) maintains detailed hydrography records as part of the hydrographic network. The bulk of the relevant information, but not all available data, is published as “PINNEENA”, referenced above.
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The river height information is held by DWE. It is converted to flow data via rating tables established by measuring flow at discrete times when a technical officer visits the Gauging Station. Height information was originally collected manually by gauge readers living near the Gauging Station, usually on a daily visit to the site (often at 9am). Automatic recorders were installed later and offer continuous records. These continuous records are broken only by mechanical failure rather than by human error or holidays.
The reliability of rating curves for flood events depends on:
- the Station having been visited and gauged during flood events during its history, and - the stability of the river formation controlling the height to flow relationship at the site.
Gauging Station 209003 “Karuah River at Booral” is central to the Karuah Valley and central to the reaches of the Karuah River subject of this Study. It has the benefit both of high gaugings and of a reasonably stable stream. The highest gauging (No. 63) was taken in 1977 at GH 6.06 m (about 3 m below the highest level recorded, which occurred in 1971) and allocated a flow of 730 cu m/second. It was a “float-gauging” but is accepted by DWE as being of good quality. The second highest gauging had been attempted on 27 May 1974 at GH 5.35 m but was not adequate for rating purposes. It was repeated the next day, 28 May 1974, at GH 4.54 m, and allocated a flow of 331 cu m/second.
A file note of 8 March 1977 (DWE ref “Calc Folder 209003”) indicates surface velocity observations at levels higher than those gauged, (that is, at GH 6.6 m (4.9 m/s) and GH 9.1 m (3.2 m/s)). The note suggested those velocities be used for rating extension. Calculations yield flows that appear to have been used for the rating table adopted by DWE. This is reasonable as the River’s cross-section around the site is regular and heights recorded to date have not exceeded bank-full level. The rating table is accepted and the Department’s flow records adopted for this Study.
Flood events are thought or known to have occurred in the Karuah Valley as:
a) Prior to the establishment in October 1968 of Stn 209003 “Karuah River at Booral”: 1913, 1927, 1946, 1956 (The specified dates actually refer to Stroud, which may or maynot experience flooding concurrent with the Karuah River itself.);
b) After its establishment but prior to continuous recording (commenced in August 1971): January 1971;
c) After installation of a continuous water-level recorder: as in Table 8 below.
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Table 8
Ranked Flood Series 1969 to 2007 – Karuah River At Booral
Peak Level Peak Flow Rank Date Time GH2 (m) (m AHD) Q(Ml/d) Q (m3/s) 1 21/01/1971 0900 9.30 10.35 209,400 2,423 2 13/10/1985 1146 8.86 9.91 180,400 2,088 3 4/02/1990 0327 8.60 9.65 163,300 1,890 4 8/06/2007 1320 8.42 9.47 151,300 1,751 5 20/03/1978 0403 7.98 9.03 130,100 1,506 6 8/05/2001 0750 7.87 8.92 122,000 1,412 7 12/11/1987 1438 7.48 8.53 105,300 1,219 8 4/03/1977 900 7.33 8.38 101,300 1,173 9 25/01/1972 900 7.31 8.36 100,8001 1,167 10 23/03/2004 0010 7.20 8.25 94,400 1,093 11 21/06/1969 900 7.16 8.21 93,900 1,087 12 22/03/2000 1700 7.09 8.14 95,900 1,109 13 15/07/1999 0030 7.07 8.12 89,700 1,038
Notes: 1. Discharge read from rating table for GH 7.31m, not as given in DWE records 2. Gauge zero: RL 1.05 m AHD
With respect to Table 8 above:
- the values quoted are for annual peaks greater than GH 7.0 metres, which, by chance, corresponds to a discharge of about 1000 cu m/second;
- the full annual series appears in Appendix A of this report.
In its report “Water Resources of the Lower Hunter Valley including the Karuah Valley”, (Reference 11), the Water Conservation and Irrigation Commission of NSW (now DWE) nominates the March 1963 flood as the highest recorded in the Paterson, Allyn, Williams and Karuah Rivers. Many of the WC&IC gauges used for their Report had operated since the 1940s, including Stn 209001 “Karuah River at Monkerai” since 1945. That Gauge reached a height of 16’ 7½” (5.07 m) in that event, assumed to correspond to a peak flow of 971 cu m/second listed for 1 March 1963 as the highest level recorded before the Station was closed in July 1981. It was replaced by Stn 209018 “Karuah River at Damsite #3” just downstream of Monkerai.
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DWE’s cross-section drawing for the establishment of the Station 209003 “Karuah River at Booral” nominates a highest known flood level of 35’ (10.7 m) Gauge Height, date unknown. It also states that overbank flow commences at GH 30’ (9.1 m) and that there are “breakaways” above GH 40’ (12.2 m). The information is likely to have been hearsay gathered at the time of planning the Gauging Station and used to determine the maximum height to which gauges should be installed. It is not considered definitive enough to include as a height record for this Study.
DWE took a cross-section of the Karuah River 120 m downstream of the bridge at Booral on 24 October 1974, estimating that the location acted as “control” for Station 209003 in high events. The surveyrecords a flood-plain 155 m wide at about RL 12.5 m AHD (GH 11.4 m), on the northern bank near the Station. The underside (soffit) of the bridge is recorded as being 12.65 m AHD.
The Department of Main Roads (DMR, now RTA) plan of 1944 for the current bridge at Booralindicates a level of 92’ for the 1894 flood, presumed the highest known in 1944. That flood level measures 0.99 m below soffit level on the drawing. Using the soffit level from the DWE’s 1974 survey gives a flood levelfor 1894 of 11.66 m AHD (GH 10.6 m).
It should be noted that the DWE gauge is physically located on the eastern bank of the Karuah River, some 20 metres downstream of the RTA’s Booral Bridge.
With respect to the occurrence of the overbank flow at GH 9.1 m above (10.15 m AHD), it is noted that the ground survey of Karuah immediately upstream of the gauge at Booral shows the top of bank at RL 11.4 m AHD and thus overflow at RL 10.15 m AHD seems questionable.
The highest known levels of GH 10.7 m from the DWE drawing and GH 10.6 m from the DMR drawing (adjustment outlined above) are a good match. This may be due to them coming from the same source however, even though over 20 years separate the research that would have lead to their adoption.
Bureau of Meteorology
The Bureau of Meteorology maintains a network of rainfall gauges, either:
- daily read; or - continuous time versus rainfall recorders (pluviometers);
The rainfall stations in and around the Karuah River catchment were extracted from the Bureau’s data base. The listing of the daily rainfall stations and pluviometers is reproduced as Appendix B, while their positions are plotted on Figure 3.
It will be noted:
- from Figure 3, there are only seven daily rainfall stations in the Karuah River catchment;
- from Appendix B, there are only two daily rainfall stations that are currently operational (Stroud and Wallaroo State Forest);
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- from Figure 3, there are no pluviometers on the catchment and the nearest instruments are located at Chichester Dam and a grouping of three instruments near Williamtown.
The relevant rainfall stations for this study are listed in Table 9 below.
Table 9
Relevant Rainfall Stations
No. Name Date Start Type
61071 Stroud Post Office 1889 Daily
61076 Raymond Terrace 1938 Daily (Wallaroo State Forest) 60042 Craven 1961 Daily 61151 Chichester Dam 1960 Pluvio
61078 Williamtown RAAF 1952 Pluvio
3.4 Resident Interviews
As part of this study, three hundred and sixty seven (367) questionnaires were issued to land owners along the riverine corridor within the study area. Sixty eight (68) questionnaires were returned, though none provided information to justify the cost of ground survey to level any flood marks to Australian Height Datum (AHD).
A “doorknock” program was undertaken upstream of Booral to identify long term residents and to determine if they were able to identify flood levels for the 2007 flood and any “highest known flood” marks.
Thirteen (13) flood marks were identified during the “doorknock” program. Table 10 below indicates the locations of the surveyed marks, the survey flood levels and a brief synopsis of the residents’ comments.
For identification purposes, the location of the identified marks is shown on Figures 13 and 14.
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Table 10 Results of Additional Survey from Resident Interviews
Co-ordinates (MGA) River Distance Level Flood Year Comment E N (m) (m AHD)
1 398703.0 6420811.5 2930.0 >40.55 1988 Above ground level (1m) at gate post 398719.4 6420830.2 2930.0 <38.84 2007 2007 below pump shed floor 2 398891.3 6420449.3 3310.0 <37.27 2007 Between guide posts 398890.5 6420451.1 3310.0 >36.98 2007 Between guide posts 3 399088.9 6420325.9 3655.0 39.85 1978 Top of mark, South Pier, Railway Bridge 4 399239.6 6419953.1 4135.0 <38.94 Highest recorded Below garage floor level 399239.6 6419953.1 4135.0 >38.39 Highest recorded Above steps to garage 5 399088.9 6419206.7 5315.0 >36.38 Highest recorded flood above roof of lower pump 399088.9 6419206.7 5315.0 <38.12 flood below ground of upper pump 6 398670.2 6419054.0 5926.0 <36.65 2007 Below haunch on bridge pier 7 401314.0 6414029.7 12586.0 26.63 Highest (1955) Up to pipe entry to back of Elec. Box 401320.2 6414056.8 12586.0 23.02 2007 To base of post 8 403006.5 6386778.1 45000 1.365 Highest recorded Water never been higher than wharf since 1940
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4. HYDROLOGICAL INVESTIGATION
4.1 Overview
The study catchment is shown on Figure 2.
The catchment areas of relevance are:
- Karuah River @ Stroud Road: 337.5 sq km - Mammy Johnsons river @ Stroud Road: 314.4 sq km - Ram Station Creek (near Stroud Road): 81.6 sq km - Karuah River downstream of Ram Station Creek: 733.4 sq km - Karuah River downstream of Stroud: 877.5 sq km - Karuah River at Booral: 974 sq km - Karuah River at Karuah: 1,456 sq km
The process envisaged for this study involves use of a riverine model to predict flood levels through the study area. Inputs to the riverine model are flood flow hydrographs, derived from hydrological analysis.
A number of hydrological investigations are required as input to the riverine investigation offlooding and as checks against the results of the riverine investigations.
For the Karuah River, the required investigations can be categorised as:
- development of a rainfall-runoff-routing model to enable the development ofpredicted flood inflows to the riverine system;
- development of appropriate "design" rainfall volumes and rainfall temporal patterns so that "design" hydrographs resulting from the "design rainfall" can be derived;
- flood frequency analysis of historically recorded flood events to enable extrapolation to rarer or "design" events and as a cross-check against the results of the hydrological model.
The above three aspects are addressed below.
It should be noted that the assumption that "design rainfall of a particular frequency (return period) will create a flood of the same frequency", is implicit in the above approach. Such an assumption is reasonable in the coastal areas of New South Wales, but becomes questionable in the western areas of the state.
4.2 Hydrology Model - Karuah River
Current Australian practice for estimation of flood hydrographs for catchments ofsimilar size to the Karuah River involves use of rainfall runoff-routing models. "Australian Rainfall and Runoff" (Reference 1) identifies suitable models as RORB, WBNM and RAFTS. Other models that could be used involve unit hydrograph techniques or time-area diagrams.
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Previous flood studies of the Karuah include “Port Stephens Flood Study” of July 1996 by Manly Hydraulics Laboratory for Port Stephens and Great Lakes Shire Councils (Ref. 8). That study examined flooding around Port Stephens itself, but required a flood model for the Karuah River as one of its inputs. A WBNM runoff routing model was used, with 53 sub-catchment areas, and was calibrated for the Gauging Station at Booral, using the January 1971 and March 1978 flood events.
In this study, RORB has been chosen, principally because:
- all three suggested suitable models are quite similar;
- review of available flood and rainfall data showed the 1990 and 2001 floods as better events for calibration as opposed to January 1971;
- parts of the sub-catchment layout, when used in a WBNM model, indicated little flood flow routing along a reach where, in reality, significant flood routing was expected;
- RORB has been used for the longest period historically;
- the consultant's experience with use of this model.
The RORB model layout is shown on Figure 4. The model comprises of 53 sub-areas and 79 notional storages (representing individual river reaches). The same sub-catchment layout as used in Reference 8 has been used for the RORB model
Calibration of the model was undertaken for Gauging Station 209003 “Karuah River at Booral” using the highest three floods recorded with good flow data as well as good rainfall data from pluviographs at Chichester Dam and at Williamtown RAAF Base. The floods identified were 1978, 1990 and 2001. Two other high floods (1971 and 1985) were not analysed because some data was lacking for each event, namely:
- flow data for 1971; - rainfall for 1985.
Initially, the 1977 flood and the 2007 flood were excluded because of having a relatively low flood volume (1977) or lack of available data. However, during the calibration of the hydraulic model, it became evident that the 1977 and 2007 floods required investigation for comparison against historical flood data.
The two pluviograph stations are used to enable examination of storm variation across the Karuah River catchment. They are taken to represent the upper and lower parts of the catchment, respectively. In each of the three events adopted for model calibration, rainfall varies between the coast and inland but not consistently. The comparative 4-day total rainfalls are listed in Table 11 below.
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Table 11
Comparative 4-day Total Rainfalls
Event Flood Rank1 Chichester Total Williamtown Total (mm) (mm) March 1977 8 153 183 March 1978 5 426 1761 February1990 3 384 488 May 2001 6 280 220 June 2007 4 155 214
Notes: 1. Flood rank at Booral
By comparison, the design storms derived as described below using AR&R have higher falls on the coast than inland for short duration storms but the opposite for long durations. The 1978 and 2001 events conform to that variant but 1990 does not.
For calibration runs of the RORB model, sub-catchments upstream of midway down the model (ie 26 sub- catchments) have the Chichester rainfalls applied. Those below have Williamtown. The change-over point corresponds to a location between Stroud and Stroud Road.
Calibration was undertaken by varying model parameters to achieve best fit of the synthesised hydrograph to that measured at Booral. Peak flow rate should be a reasonable match as well as hydrograph shape. The principal parameters required to achieve model calibration are routing parameters (kc and m) and the rainfall loss model adopted. As only three floods are tested and as there are no unusual features to the Karuah catchment, a standard value of 0.8 is adopted for parameter ‘m’. All three floods demonstrated their best fit with the other routing parameter Kc set at a value of 65. This value is very close to the Australia wide Dyer (1994) value suggested within RORB by Pearse (2002).
In calibration the Initial Loss / Continuing Loss model was chosen and each part is varied by trial and error
(simultaneously with Kc) to investigate fit to the recorded hydrograph.
Continuing Losses varied over the three storms initially fitted (3.5 mm/hour in 1978, 2.5 mm/hour in 1990 and zero in 2001). In the 1977 and 2007 floods, the continuing loss was ascertained at 0.8 and 1.80 millimetres per hour respectively. All values are reasonable.
A Continuing Loss of 2.5 mm/hour was adopted for all design storm runs. This value is both a good average of the calibration runs and a value often suggested when no other is available.
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Initial Losses varied for each of the three historical rainfall events, according to how early or late in the event data was considered to be included. It is therefore somewhat arbitrary. Falls up to about the time of rise of the recorded hydrograph were removed as Initial Loss (80 mm, 60 mm and 40 mm for the 1978, 1990 and 2001 storms respectively, while 20 and 15 millimetres were removed for the 1977 and 2007 events). To acknowledge the reality of Initial Loss, a fixed value of 25 mm was adopted for design storms.
A comparison of modelled and recorded values for the floods tested appears in Table 12 below, while Figures 5, 6, 7 and 8 illustrate the comparison.
In the 2001 event a hydrograph was also recorded well upstream of Booral, at Station 209018 “Karuah River at Damsite #3”. That information is included in testing for parameters and its fit is also presented in Figure 7.
Table 12
Comparison of Modelled and Recorded Peak Discharge (Karuah River at Booral)
Flood Peak Discharge (cu m/sec)
Recorded Modelled
1977 1,170 1,256 1978 1,505 1,500 1990 1,888 1,835 2001 1,409 1,191 2007 1,189 1,193
Difficulties were experienced with calibration of the 1977 and 2007 flood events. Initial application of the Chichester and Williamtown pluviographs produced discrepancies in the 1977 event in that the modelled flood hydrograph is a single peak feature, while the recorded flood hydrograph is a distinct double peak event.
The best fit between the recorded and modelled hydrographs was derived by:
- changing the assumed daily rainfall distribution whilst maintaining consistency of the records at individual stations;
- changing the assumed distribution of the available pluviographs;
- treating each day of rainfall as a separate burst with separate continuing loss rates assumed for each burst.
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A reverse problem was experienced with the 2007 flood, where the recorded event is a single peak flood with a steep recession curve, while the initial modelled results indicated a double peak with a gradual recession. The best fit for the 2007 event (as shown on Figure 8) was achieved using the same technique of a trial and error variation of adopted pluviograph distribution and adopted continuing loss.
Clearly, the difference between a single peak and a double peak phenomena follows the assumptions of rainfall distribution across the catchment. At this point, there is not enough data to enable a better assessment of rainfall across the catchment. Similarly, the RORB model calibration has shown that rainfall (both in total rainfall and storm intensity) can vary markedly across the Karuah River catchment in flood producing rainfall events.
4.3 Design Flood Hydrographs
For design runs of the RORB model, intensity-frequency-duration (IFD) data was derived according to AR&R. Initial runs of the model used one “inland” site to represent falls in the upper catchment and a “coastal” one for the lower catchment. At the critical duration of 36 hours derived in this Study, those inland design intensities were generally about 15% higher than coastal. Given this relatively small difference (compared with much larger variations such as those seen on the above Table 11 for the calibration storms), upper versus lower catchment variance is considered unnecessary for design purposes. A single design intensity was therefore applied across the Karuah catchment, rather than inland and coastal ones.
The adopted IFD data appears as Appendix C of this report.
Within RORB an Areal Reduction Factor according to AR&R Figure 2.6 was applied. The factor (depth- area ratio) applied was 0.9 for the full Karuah catchment. Similarly, a uniform areal distribution and temporal pattern was adopted.
The RORB model parameters used were those as derived from the model calibration, namely:
- Parameter kc: 65 - Parameter m: 0.8 - Initial Loss: 25 millimetres - Continuing Loss: 2.5 millimetres per hour
The model was run with the adopted parameters for all design storms. Storm frequency / rarity varies from 50% AEP (1-in-2-year ARI) to 0.5% AEP (1-in-200-year ARI). Various stormdurations (varying between 12 and 72 hours) were run but all frequencies demonstrate their highest peak flow at 36 hours for all sites, except the catchment outlet. There the 48 hour storm gives marginally higher peaks for all but the 0.5% AEP frequency (which reverts to 36 hours). The margin of difference is so small that 36 hour results could be used for all intents and purposes.
Table 13 below lists the peak flood discharges as derived using the RORB model with various return period rainfalls for the Karuah River at Booral and at Karuah.
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Table 13
Peak Discharges – Design Floods (Source: RORB model using ARR rainfall)
Frequency Peak Discharge (cu m/sec) AEP ARI Karuah River Karuah River (Percent) (yrs) at Booral at Karuah
0.5 200 3,885 4,790 1.0 100 3,313 4,060 2.0 50 2,758 3,354 5.0 20 2,106 2,508 10.0 10 1,627 1,918 20.0 5 1,244 1,453 50.0 2 713 822
For comparative purposes, the design hydrographs for the 1% AEP, 36 hour storm are shown on Figure 10 for the various tributaries to the Karuah River, while Figure 11 illustrates the predicted total flow in the Karuah River at Booral and at Karuah for the 1% AEP 36 hour storm design event.
4.4 Estimation of PMF
The Probable Maximum Flood (PMF) is generally defined by the catchment response to the Probable Maximum Precipitation (PMP).
The PMP has been defined by the World Meteorological Organisation (1986) as “the greatest depth of precipitation for a given duration, meteorologically possible for a given size storm area at a particular location at a particular time of year, with no allowance made for long-term climatic trends.”
The Bureau of Meteorology has published three guide books (References 12, 13 and 14) for the estimation of PMP rainfall in Australia.
Broadly, the Bureau advocates the use of one of three methods, subject to the catchment size and the location of the catchment.
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The three methods are:
- Generalised Short Duration Method (GSDM) (revised); - Generalised Tropical Storm Method (GTSMR); - Generalised South East Australia Method (GSAM).
The catchment location of the Karuah River places it in the transition between GSAM and GTSMR areas. The catchment size (974 sq kilometres at Booral and 1457 sq kilometres at Karuah) places the Karuah as beyond the catchment size limits for application of the GSDM approach.
The PMP rainfalls for the GSAM and GTSMR methods were derived using the Bureau of Meteorology guide books (References 12 and 13) for various duration storms as listed in Table 14 below.
Table 14
PMP Rainfall Estimates (Karuah River at Karuah)
PMP Rainfall Storm Duration (mm) (hrs) GTSMR GSAM GSDM 3 Not applicable Not applicable 345 6 “ “ 443 24 742 754 Not applicable 36 874 858 “ 48 996 920 “ 72 1212 1000 “ 96 1377 1068 “ 120 1454 Not applicable “
The Bureau suggests that the 12 hour PMP storm rainfall be derived by interpolation between the 6 hour GDSM method and the 24 hour duration rainfalls listed in Table 14 above. Such interpolation gives the 12 hour PMP rainfall for the Karuah River catchment as 580 millimetres.
The PMP rainfalls were applied to the calibrated RORB model and produced peak discharges for the Karuah River at Booral and Karuah as listed in Table 15 below.
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Table 15
Peak Discharges - PMF (Source: GSAM Method)
Peak Flow Storm Duration (cu m/sec) (hrs) At Booral At Karuah 12 9,669 12,313 24 9,201 12,713 36 7,042 10,448 48 7,353 9,919 72 6,940 9,599 96 5,156 7,083
Review of Table 15 shows the “critical” duration for the PMF as lying between the 12 and 24 hour duration. For the purposes of this study, the 24 hour duration has been adopted for the PMF, given:
- the PMF is primarily used for emergency planning purposes;
- the 24 hour storm is the largest at Karuah and only 5 percent less than the 12 hour storm at Booral;
- the 24 hour event, having a larger flood volume, should have more storage routing, as the flood passes through the river system. This difference will be demonstrated by the hydrodynamic model.
In comparison between the “critical” duration for the PMF (24 hours as above) versus the more frequent design storms (36 hours, as outlined earlier), it should be noted that the estimated floods produced are very dependent on the rainfall temporal pattern applied and that the temporal patterns from Australian Rainfall and Runoff (Reference 1), as applied to the design storms, are different to those recommended by the Bureau of Meteorology for the PMF estimation.
Figure 12 provides a comparison between the PMF hydrographs and the design 1% AEP flood hydrographs at Booral and Karuah.
4.5 Flood Frequency Analysis
The object of flood frequency analysis can be viewed as:
- estimation of the recurrence interval of particular sized floods;
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- estimate the recurrence interval for a particular historical flood;
- extrapolate flood behaviour beyond the historical record or interpolate within the historical record period.
The preferred methods of flood frequency analysis in Australia (see Australian Rainfall and Runoff - Reference 1) involve:
- use of peak flood discharges as frequency plots of peak flood height often exhibits discontinuities which affect the analysis;
- use of Log Pearson III as the preferred frequency distribution.
The process generally undertaken for the Karuah River at Station 209003, "Karuah River @ Booral" was thus:
- conversion of flood heights from a gauge reading to flood discharge using the appropriate height versus discharge table (a rating table),
- assembly of an annual series of flood discharges;
- ranking the flood heights from largest to smallest;
- assigning a frequency plot position to the historical events using the Cunnane formula (Reference 1, Equation 10.5);
- fitting a probability distribution to the plotted data. The plotted data has been fitted to both Log Pearson III (LPIII) distribution and the Generalised Extreme Value (GEV) distribution.
Both Log Pearson III and Generalised Extreme Values are mathematical statisticaldistributions widelyused for flood frequency analysis.
The plotted flood frequency appears on Figure 9 (for both LPIII and GEV distributions). Figure 9 also illustrates the plot positions of the 19 largest events (with return period greater than once in 2 year ARI) rather than the complete series of all events.
It should be noted that:
- the peak discharges for various frequencies, as derived from Log Pearson III distribution, are given in Table 16 below;
- the actual historical floods plot below the Log Pearson III distribution and the GEV distribution (with a 1% AEP peak discharge of about 800 cu. m/sec);
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- in fitting the Log Pearson III distribution, the complete annual series is used and thus the historical data plots lower than the distribution for rare floods and above the distribution for more frequent flood events.
- comparison between the historical data, the LPIII distribution and GEV distribution, indicates the GEV distribution as the better fit to the historical information.
- the historical events plot between the derived flood discharges and the 95% confidence limit;
- the flood frequency has been derived by “Method of Moments” using logarithm of discharges as recommended by ARR (Reference 1)
Table 16
Peak Flood Discharges - "Karuah River @ Booral" (Source: Frequency analysis of historical data)
Frequency Peak Discharge (cu m/sec) AEP ARI Log Pearson III Confidence Level (percent) (yrs) Distribution – 5% + 5%
0.5 200 3,634 1,583 8,346 1.0 100 3,220 1,687 6,148 2.0 50 2,786 1,730 4,488 5.0 20 2,184 1,637 2,915 10.0 10 1,711 1,414 2,070 20.0 5 1,226 1,074 1,400 50.0 2 573 561 586
Frequency Peak Discharge (cu m/sec) AEP ARI GEV Distribution Confidence Level (percent) (yrs) – 10% + 10% 0.5 200 2,907 2,306 4,711 1.0 100 2,710 2,192 4,043 2.0 50 2,477 2,024 3,386 5.0 20 2,099 1,720 2,642 10.0 10 1,747 1,418 2,106 20.0 5 1,329 1,054 1,609
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Frequency Peak Discharge (cu m/sec) AEP ARI GEV Distribution Confidence Level (percent) (yrs) – 10% + 10%
50.0 2 649 484 833
4.6 Comparison of Results
The investigation of previous documents for the historical flood frequency and the RORB modelling produce a variety of flood flow estimates for the Karuah River at Booral. The flow estimates are listed in Table 17 below. Table 17
Comparison of Peak Flows, Karuah River at Booral
Frequency Historical Sourced Information This Study (AEP) PWD 1 DWR 2 MHL 3 LP3 4 GEV 4 RORB5 1 percent 3,313 3,036 2,253 3,220 2,710 3,313 2 percent 2,910 2,580 1,870 2,786 2,477 2,758 5 percent 2,462 2,315 1,330 2,184 2,399 2,106 10 percent 2,000 1,745 1,030 1,711 1,747 1,627
Notes: 1. From Untitled Calculation Folder (Section 3.2) – Refer Section 3.2 2. Reported in Reference 8, 1967 to 1980 – Refer Section 3.2 3. Reference 8 – Refer Section 3.2 4. Section 4.5 of this Study 5. Section 4.3 of this Study
Comparison between the design flood discharges (derived in this study) produced by the RORB model for the Karuah at Booral and peak discharges produced by the frequency analysis of the historical record (as indicated by Table 17 above and Figure 12) shows the RORB model as producing reasonable results for design purposes.
It is noted that the flood discharges produced in this study are not significantly different to earlier studies (with the exception of the Port Stephens investigation as discussed earlier).
The RORB model has been structured to provide tributary inflows to the Karuah hydro-dynamic model.
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5. HYDRODYNAMIC INVESTIGATION
5.1 Overview
The object of the hydrodynamic models is to convert flood hydrographs to flood levels at particular locations.
The study area of the Karuah River from Stroud Road to Karuah is essentially long and linear.
The end use of this flood study is seen as:
- Providing tail water levels for future flood studies at Stroud.
- Providing flood behaviour data for future development controlalong the Karuah River.
Given the above topographic considerations and the end use of the flood study, a one-dimensional hydrodynamic model which models both flood conveyance and flood storage is appropriate.
There are a number of available models with the ability to meet the study demands. These include:
- MIKE-11 - RUBICON -ISIS - SOBEK - ESTRY
In this instance, MIKE-11 has been chosen principally on the basis of its widespread acceptance and the consultant’s familiarity with the program.
5.2 MIKE-11 Model of the Karuah River
The MIKE-11 model of the Karuah River comprises:
- A single river reach representing the Karuah River from upstream of Stroud Road to Karuah.
- Five notational L looped branches to represent the bridge crossings at Stroud Road (railway crossing), the Washpool Bridge (RTA), the RTA bridge at Booral plus the two bridge openings below the approach road to the Booral Bridge.
- Twenty eight surveyed cross sections
The location of the surveyed cross sections is shown on Figures 13 and 14. The locations of the cross sections were selected so that reasonable estimates of waterway area and flood storage would be derived in the MIKE-11 model.
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It is noted that:
- The road bridges across the Karuah River at Stroud Road and Stroud are low leveland without embankments for the approach road. These structures will be “drowned out” during major floods and will not affect flood behaviour in large events.
- The Pacific Highway Bridge and the Karuah Bypass bridge are well elevated above likely flood levels and thus will not affect flood behaviour.
- The road crossings of the Karuah River at Washpool (Stroud-Dungog Road) and Booral and the railway bridge and its approach bridges at Stroud Road are slightly elevated above the floodplain and have elevated approaches. Thus, they will affect flood behaviour for floods higher than the “top of bank” for the Karuah River and have been included in the MIKE-11 model.
Table 18 below tabulates the surveyed cross-sections and the assigned distances (“river distance” plus identified localities as used in the MIKE-11 model.
Table 18
Localities and Cross-Sections – River Distance
Location River Section1,2, 3 River Distance (m) Start of model NS 2,026 K1 2,525 Low level bridge, Stroud Road NS 3,353 Bridge, North Coast Rail, Stroud Road S1 3,655 K2 3,732 Confluence, Mammy Johnsons Creek NS 4,702 K4 4,878 K4 5,791 Confluence, Ramstation Creek NS 5,885 HDWB_Level #1 NS 5,918 High Level RTA bridge, "Washpool" S2 5,956 K4.5 7,606 K5 10,149 K6 10,506 K7 12,074 Low level Bridge, Stroud NS 12,415 HDWB_Level #2 NS 12,478
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Location River Section1,2, 3 River Distance (m) K8 13,061 Confluence, Mill Creek NS 13,973 K9 14,003 K10 14,714 K11 16,229 HDWB_Level #3 NS 17,402 Confluence, Alderley Creek NS 18,513 K12 18,774 K13 19,733 K14 21,247 Bucketts Way bridge, Booral S3 , K15 21,902 HDWB_Level #4 NS 21,948 K16 22,360 Confluence, Booral Creek NS 23,170 K17 23,218 K18 24,718 K19 25,278 HDWB_Level #5 NS 25,512 K20 26,822 K21 27,861 Allworth, Upstream NS 31,030 K22 31,145 Boat Ramp, Allworth NS 31,542 HDWB_Level #6 NS 31,741 K23 33,362 K24 35,496 Confluence, The Branch NS 36,548 K25 38,592 Confluence Limeburners Creek NS 41,237 K26 42,461 Karuah By-pass NS 43,364 K27 45,406 K28 47,002
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Location River Section1,2, 3 River Distance (m) Karuah Bridge, Pacific Highway NS 47,013 End of model NS 47,029
Notes: 1. Cross-sections K1 to K28 surveyed for this study 2. Cross-sections S1 to S3 surveyed for this study as part of bridge detail surveying 3. Cross-section not surveyed, tabulated “NS” for location only
Figure 15 provides a schematic representation of the MIKE-11 model.
From Figure 15, it will be noted that separate branches have been used to model:
- elevated bridges at Stroud Rail, Washpool and Booral;
- floodplain branches with appropriate structures have been used to model: o approach spans to railway bridge at Stroud Rail o cattle underpass at Washpool; o small bridges on the northern approach to the RTA bridge over the Karuah River at Booral
Flood inputs into the MIKE-11 model are identified technically as “boundary conditions”.
The boundary conditions for the MIKE-11 model comprise:
- Eight hydrographs inputs derived from the RORB model
- A single tailwater level at Karuah showing a tidal variation as a reproduction of the Port Stephens water levels.
Table 19 lists the hydrograph inputs and the input river distance.
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Table 19
Hydrograph Input Location
Hydrograph River Distance (m) Karuah River @ Stroud Road 2,026 Mammy Johnson’s River 4,702 Ram Station Creek 5,885 Mill Creek 13,973 Alderley Creek 18,512 Casey Creek 29,119 The Branch 36,548 Lime Burners Creek 41,237
As noted earlier, Figures 10 and 11 illustrate the design hydrographs for each input point for the design 1% AEP, 36 hour design storm.
The tailwater levels used in Port Stephens vary for each historical flood and design flood tested. Derivation of the tailwater levels for Port Stephens is addressed in the following sections dealing with model calibration – verification and design flood events.
5.3 MIKE-11 Model Calibration and Verification
The data for model calibration and verification along the Karuah River is limited and comprises:
- 1976 flood levels at Booral plus four levels from HDWB peak level indications;
- 1977 flood levels at Booral plus five levels from HDWB peak levels;
- 1978 flood levels at Booral plus five HDWB levels;
- 1990 and 2001 flood levels at Booral only;
- 2007 flood with four flood levels identified by resident interview plus the Station 209003 “Karuah River at Booral”;
- historically “recorded” peak levels from bridge structures (3 levels) with two historical peak levels from resident interviews.
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With respect to the above flood level data, it is noted:
- The 1978, 1990, and 2001 floods were used in the RORB model calibration. Table 12 indicates a good fit between the RORB model and the modelled flows andthe recorded flows.
- The 1977 and 2007 floods were also tested with the RORB model, which produced a reasonable comparison between recorded and calculated levels.
- The recorded water levels for the HDWB peak level indicator at Booralare higher than the DWR Station 209003 “Karuah River at Booral” notwithstanding that the HDWB gauge appears to be some 50 metres downstream of the DWR gauge. For example, the HDWB peak levels for 1976, 1977 and 1978 were 6.32 m AHD, 8.43 m AHD, and 9.26 m AHD respectively compared to the DWR records of 6.32 m AHD, 8.38 m AHD and 9.03 m AHD respectively.
- The modelled hydrographs for the 1978 and the 1990 floods match the shape of the recorded hydrographs quite well. However, the 2001 modelled hydrograph shows a double peak event as compared to the single peak event recorded. The reverse applies to the 1977 event, where the modelled peak is a single peak event, while the recorded event was a double peak (see Figure 5). The initial rise in the 1990 flood (see Figure 6) is not well reproduced by the RORB model, while the comparison between the modelled and recorded flood is satisfactory for the second peak (the more significant flood rise). Iterative testing of the application of recorded pluviographs and loss rates in the RORB model has shown these discrepancies are the result of the uncertain rainfall distribution across the catchment.
In summary, there is reasonable water level and discharge data at Booral (Station 209003) but little flood level data along the Karuah River in the study area.
Given the data available, the calibration strategy adopted was:
- Testing of the 1990 flood to reproduce the rating curve for Station 209003 “Karuah River at Booral”.
- Testing with the 1978 and 1977 flood to confirm the longitudinal profiles, mindfulthat peak level indicators can be prone to error.
- Testing of the 2007 flood for comparison at Station 209003 “Karuah River at Booral” and against the flood levels indicated by the resident interviews.
- Testing with the design flood to confirm that:
- the flood frequency at Booral is reproduced;
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- the design one percent AEP flood levels are not significantlydifferent to the highest recorded flood levels noted on the various bridge drawings. This approach assumes that the highest recorded floods are likely to be in the range of the two percent AEP to one percent AEP, given there is at least some 100 years of resident knowledge available (through oral history).
For the MIKE-11 model calibration and verification, the tailwater levels at Karuah were either predicted tide levels at Port Stephens or measured water levels in Port Stephens (MHL Stations “Mallabula” and “Tomaree”). The locations of the tidal stations are shown on Figure 3. For each event, the Port Stephens levels adopted were:
- Predicted tide levels: 1977, 1978 and 1990; - Measured tide levels: 2001 and 2007.
The adopted tailwater levels for each event are illustrated on Figures 16 and 17.
Figure 18 illustrates the comparison between the calculated 1990 water level hydrograph (from MIKE-11) at Booral and the DWR rating table at the station. The comparison shows the MIKE-11 model reproduces the rating curve satisfactorily.
Figures 19 and 20 show the calculated flood profiles for the 1977, 1978 and 2007 floods, while Figure 21 indicates a comparison of recorded and calculated peak levels at Booral for the 1977, 1978, 1990, 2001 and 2007 floods. Table 20 below provides the calculated values of flood level (from the MIKE-11 model).
Table 20
Comparison of Historical Flood Levels (from the MIKE-11 model)
Flood Source River Recorded Flood Calculated Flood Difference Distance Level Level (m) (m) (m AHD) (m AHD) 1977 HDWB #1 5918 33.86 35.77 1.91 HDWB #2 12,478 24.05 24.11 0.06 HDWB#3 17,401 15.06 15.98 0.92 Station 209003 21,911 8.38 8.44 0.06 HDWB #4 21,947 8.43 8.29 -0.14 HDWB#5 25,512 4.93 4.64 -0.29 HDWB#6 31,740 1.64 2.16 0.52 1978 Stroud Rail 1 3,655 39.85 39.06 -0.79 HDWB#1 5,918 37.75 36.66 -1.09 HDWB #2 12,478 25.10 24.91 -0.19 HDWB#3 17,401 16.44 16.78 0.34
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Flood Source River Recorded Flood Calculated Flood Difference Distance Level Level (m) (m) (m AHD) (m AHD) Station 209003 21,911 9.03 8.92 -0.11 HDWB #4 21,947 9.26 8.78 -0.48 HDWB#5 25,512 5.87 5.07 -0.80 1990 Station 209003 21,901 9.65 9.48 -0.17 2001 Station 209003 21,901 8.92 8.24 -0.68 2007 Resident 2,930 < 38.84 37.71 -1.13 Resident 3,310 ± 37.10 37.59 0.49 Resident 5,315 < 36.0 36.01 > 0.01 Resident 5,926 < 36.65 35.41 < -1.24 Resident 12,586 23.02 23.58 0.56 Station 209003 21,901 8.42 8.47 0.05
Table 21
Comparison of Historical Levels and Design Flood Levels
Flood Source River Recorded Design 1% Difference Distance Flood Level AEP (m) (m) (m AHD) (m AHD) Other Historical Resident 2,930 > 40.55 (1988?) 2 41.54 < 0.99 Floods SRA 3,655 40.32 (1890’s?)2 41.07 0.75 SRA 1 3,655 39.85 (1978)2 41.07 1.22 Resident 3 4,136 < 38.94 (1950’s?)2 38.98 > 0.040 > 36.4 < 2.48 Resident 5,315 39.12 < 38.1 > 1.02 RTA – 38.5 (1950) 2 -0.24 5,926 38.26 Washpool 37.1 (1946) 2 1.16 Resident 12,586 26.63 (1955) 2 27.32 0.69 RTA – Booral 21,901 11.78 11.48 -0.30
Notes: 1. Mark on south pier 2. Bracketted figures give approximate date 3. Located on flood runner, lower than top of bank at this point
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In review of the flood profiles for the 1977 and 1978 events, it was noted:
- the MIKE-11 input hydrographs probably overestimate the actual flows for 1977 (as illustrated by the difference between the recorded and model hydrographs at Booralon Figure 5);
- the MIKE-11 results for the 1978 event are expected to be a better match for the recorded flood levels, as the match between the RORB model and the recorded flows at Booral is better than the 1977 event.
- there may have been some transposition errors in creating the HDWB reports fromthe original flood records (or readings), as outlined below;
Testing of the MIKE-11 model with differing estimates of flows and realistic values of Mannings ‘n` in the model did not enable agreement between the calculated flood levels and the HDWB records to be reached at:
- HDWB #1 and HDWB #3 for the 1977 flood; - HDWB #1 for the 1978 flood.
Comparison between the design 1% AEP flood and the historical marks identified at the various bridge structures indicates that the MIKE-11 values, as derived from the historical floods, are ofthe correct order.
By chance, the site inspections identified the HDWB #2, downstream of the low level road crossing at Stroud. The installation comprises of a series of one metre pipes to contain a peak level recording stick. The pipes were not numbered. Thus, a relatively common error would be to transpose the peak level reading to the wrong gauge, thus creating errors of even metres.
Further, HDWB #4 has not been identified in the field. Clearly, given the comparison of flood levels with Station 209003 “Karuah River at Booral” indicates that the peak level indicator station could be upstream of the Booral Bridge, not downstream, as assumed from available documents.
Table 22 below indicates the adopted Mannings `n’ values specified at various points in the MIKE-11 model. The Mannings `n’ value adopted for various branches not specified in Table 22 was 0.045. The values in Table 22 represent the ‘main channel” values, while overbank areas have been specified as the main channel values factored by 1.56, 2.00 and 2.33, depending on location.
Given that the hydrological analysis has indicated the sensitivity of the Karuah River to variations in total storm rainfall and rainfall patterns, the comparison between the recorded and calculated flood level values for the 1977, 1978, 1990, 2001 and 2007 floods is considered satisfactory.
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Table 22
Adopted Mannings `n’ Values
Model Reach Distance Mannings `n' Value KARUAH 2,026 0.065 KARUAH 12,073 0.065 KARUAH 13,061 0.070 KARUAH 19,733 0.070 KARUAH 21,247 0.060 KARUAH 21,902 0.050 KARUAH 27,807 0.047 KARUAH 31,145 0.038 KARUAH 35,496 0.038 KARUAH 38,591 0.034 KARUAH 47,029 0.030 STROUD_RAIL_UBRIDGE 181 0.055 STROUD_RAIL_UBRIDGE 199 0.055
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6. DESIGN FLOOD LEVELS
6.1 Process of Assessment
The Study Brief calls for definition of design flood levels for 50% AEP, 20% AEP, 10% AEP, 5% AEP, 2% AEP, 1% AEP and 0.5% AEP flood events plus the probable maximum flood (PMF).
The flood behaviour for the design events has been determined using the calibrated MIKE-11 model of the Karuah River by:
- application of the various tributary inflows into the Karuah River through the study area using the RORB model (see Chapter 4);
- application of an appropriate tailwater at Karuah, derived from Port Stephens.
- sensitivity testing of the results to changes in the model inputs.
With regard to the above analysis process, it is noted that:
- determination of the appropriate tailwater at Karuah is a major consideration and is addressed in the next section;
- the results of the design flood analysis are presented later in this report as:
- long sections of the Karuah River (by way of figures); - tabulated values (by appendices); - flood surface contour plans (by figures) - flood hydraulic categories and flood hazard categories (by figures and GIS data).
Climate change has the potential to increase mean sea levels (thus affecting the tailwater at Karuah) and to change rainfalls. In this instance, the Study Brief calls for climate change assessment for one design event. The changes to design flood behaviour through climate change is addressed in the following chapters ofthis report.
6.2 Design Tailwater Levels
The downstream boundary of the Study Area is at Karuah. At this point, water levels in the Karuah River are controlled by the prevailing water levels in Port Stephens, which in themselves are tidally influenced
Two scenarios for flooding in the lower parts of the Karuah River are possible and (for the purposes ofthis study) have been categorised as:
- River flooding (caused by runoff); - Ocean flooding (caused by elevated ocean water levels).
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The flooding scenarios are not directly related and thus, common practice is to derive design flood levels as the maximum of the possible flooding scenarios (either river flooding or ocean flooding).
An assessment of the flood height differences in Port Stephens at Karuah is given below.
For river flooding, the maximum tailwater level for Port Stephens at Karuah and in the MIKE-11 model is RL 1.06 m AHD, comprising:
- mean sea level: RL 0.0 m AHD; - astronomical tidal variation: 0.9 metres; - tidal amplification and friction losses from Karuah to the ocean: 0.16 metres Maximum Level: 1.06 metres
For ocean flooding, the “Port Stephens Flood Study – Design Water Levels and Wave Climate” (Reference 8) provides information that can be used directly or deduced for application to the Karuah Flood Study. Table 6 of this report (source Reference 8) provides design flood levels for Port Stephens for 5%, 2%, 1% and Extreme events (level of RL 1.76, RL 1.83, RL 1.91 and RL 1.97 m AHD respectively) while the 50%, 20%, 10% and 0.5% AEP flood levels have been derived by interpolation as RL 1.48, RL 1.62, RL 1.70 and RL 1.98 m AHD by interpolation of the information in Table 6 using normal probability plotting.
Figure 22 indicates the adopted maximum tailwater at Karuah applied to the semi-diurnal astronomical ocean tidal variation for both the river flooding and ocean flooding scenarios.
It is noted that the Port Stephens Flood Study (Reference 8) has adopted the highest values of flood levels at Karuah, comprising ofcoincident occurrence of ocean tide, wind set-up and stormsurge, reaching a peak level of RL 1.91 m AHD.
6.3 Calculated Design Flood Levels
The calculated design flood levels for the 50%, 20%, 10%, 5%, 2%, 1% and 0.5% AEP event plus the Probable Maximum Flood (PMF) appear:
- in table format in Appendix D “Design Flood Levels”; - in graphical long section format on Figures 23, 24 and 25.
With respect to the calculated design flood levels, it is noted that:
- all the design floods have been derived from MIKE-11 runs with the same water level conditions at Port Stephens, with a peak level of RL 1.06 m AHD, thus no correlation between river flooding and ocean storm surge has been implied;
- where the design flood levels produced by MIKE-11 are less than the ocean flooding conditions adopted in the Port Stephens Flood Study (Reference 8), the higher flood levels have been used to override the MIKE-11 results. This approach ensures that the design flood levels represent an envelope of possible events.
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- typically, the PMF flood varies between 5 and 9 metres above the design 1% AEP event upstream of Booral and up to 5 metres above the design 1% AEP event downstream of Booral;
- typically, the design 0.5% AEP event is up to 1 metre higher than the design 1% AEP event, depending on location;
- the existing RTA bridges are above the design 1% AEP event, though they will be overtopped in a PMF event. The 0.5% AEP floods will inundate the underside of the bridges but not overtop the bridge deck.
- The reaches of the Karuah River downstream of its confluence with The Branch are affected by the prevailing water level in Port Stephens. This point is demonstrated by the diminishing differences between the eight design floods as the Karuah reaches Port Stephens.
Table 23 below tabulates the peak water levels along the Karuah River for the various design floods.
Figure 28 illustrates a diagrammatic representation of the comparison of flood levels and ground levels for the Karuah River near Stroud.
Table 23
Design Flood Levels, Karuah River
Return Karuah River Period At Booral At Mill At RTA At Rail 1 (% At Karuah At Allworth (m AHD) Creek Bridge at Bridge Stroud AEP) (m AHD) (m AHD) Confluence “Washpool” Road (m AHD) (m AHD) (m AHD) 50 1.48 1.61 7.06 20.46 34.70 36.77 20 1.62 2.26 8.45 22.07 35.86 38.33 10 1.70 2.71 9.23 22.97 36.39 39.74 5 1.76 3.70 10.45 24.61 37.29 39.78 2 1.83 4.02 10.70 25.04 37.75 40.47 1 1.91 4.59 11.48 25.67 38.26 41.01 0.5 1.98 5.12 12.24 26.28 38.75 41.53 PMF 1.98 9.59 18.08 32.05 42.46 45.25 Notes: 1. Taken from Port Stephens Flood Study (Ref. 8) or interpolated
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7. SENSITIVITY ANALYSIS
The design flood levels outlined in Chapter 6 rely on the hydrodynamic model (MIKE-11), which itself is influenced by:
- the model calibration and verification process; - the adopted flood discharges along the Karuah River; - the adopted friction in the river system.
The examination of sensitivity of predicted flood levels to changes in model parameters has been based on the design 1% AEP flood event with a varying tailwater level at Karuah, with a peak level of RL 1.06 m AHD, and variations from that event.
Table 13 indicates peak flood discharges for the Karuah River at Booral and Karuah. Thus:
- the 0.5% event represents the design 1% AEP event plus a 17 percent increase in discharge; - the 2% AEP event represents a 17 percent decrease in discharge.
Additional sensitivity testing has been undertaken to examine the impact on design flood levels for the design 1% AEP flood event for:
- an ocean flooding event;
- a climate change induced variation in ocean level;
- concurrence of the peak flood outflow with both the maximum tide level in the tidal cycle and the minimum tide level in the tidal cycle;
- simple increases of 20 percent for design inflows into the MIKE-11 model and 20 percent increase in the friction allowances in the MIKE-11 model (as represented by Mannings `n’).
Appendix F details the calculated flood levels for the various sensitivity tests, namely:
- the 1% AEP 36 hour design event with peak river flood flows concurrent with a maximum tidal level of 0.9 metres at Port Stephens. This event has been used as the base case for comparison.
- The 1% AEP 36 hour design event with the peak river flood coincident with the minimum tidal cycle level. This test, with comparison to the previous test, indicates the effect of the tidal cycle propagating upstream.
- The design 1% AEP 36 hour design event, concurrent with the 0.9 metre tidal level together with a 0.8 metre allowance for a climate change induced ocean level rise (the maximum predicted by IPCC for the projection period to 2090/2099).
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- The 1% AEP flood with the inflows factored by 1.2, to represent a 20% increase in flows as a measure of the sensitivity of design flood levels to changes of this magnitude;
- The 1% AEP flood using the MIKE-11 model with the friction in the model (the dominant factor in the Karuah River) increased by 20 percent.
The sensitivity testing is shown graphically on:
- Figure 26 for the Karuah River above Booral; - Figure 27 for the Karuah River below Booral.
Figures 26 and 27 show the base case (the 1% AEP event) with the cases where the flow and the model friction have been increased by 20 percent.
The two cases with the 20 percent increase in flow or friction produce similar results. This is expected, given the limited flood storage in the Karuah River and the dominance of friction as evidenced in the MIKE-11 model.
Typically, the cases of increased flow (that is, flow increased by 20 percent) and increased friction (that is, friction increased by 20 percent) are between 0.8 and 1.2 metres above the design 1% AEP event.
The results tabulated in Appendix D indicate flood level differences for the base case (1% AEP) plus 17 percent flow (the 0.5% AEP), the flood levels vary between 0.44 metres and 1.0 metres upstream of Allworth.
Similarly, for the base case (1% AEP) less 17 percent flow (the 2% AEP), the design flood levels upstream of Allworth vary between -1.11 metres and -0.46 metres. The greatest difference in flood levels between the base case plus 17 percent (0.5% AEP) and the base case less 17 percent AEP occur between the confluences with the Karuah River of Mill Creek and of Alderley Creek.
Figure 27 is used to demonstrate the impact of assumptions of prevailing water levels at Port Stephens as those water level impacts propagate upstream.
With respect to Figure 27, it is noted that:
- the impact of flood timing compared to tidal cycle timing affects downstream of The Branch confluence. The maximum difference in flood levels is of the order of 0.4 metres. The last 4 kilometres of the Karuah River indicate the influence of the peak tidal level, even though the design flood has been adjusted such that the peak river flood occurs concurrently with the minimum levels of the tidal cycle.
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- In the last 3 kilometres of the Karuah River, under current (2008) conditions, flood levels for a design 1% AEP event are controlled by the ocean level, while upstream of this point, flood levels are controlled by river flooding;
- The impact of climate change induced increases in ocean level will occur as far upstream as Allworth, though the more severe increases (above 0.20 metres) occur downstream of The Branch confluence. The predicted rise in flood levels diminishes moving upstream from 0.8 metres at Port Stephens to 0.1 metre at Allworth.
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8. PRELIMINARY ASSESSMENT OF CLIMATE CHANGE IMPACTS
This chapter presents a preliminary analysis of the impact of climate change on ocean level and rainfalls using information as was available in September 2008. Further assessment will need to be undertaken for the Floodplain Management as more up-dated information becomes available.
If the predicted changes to climate (as a result of the impact of “green house” gases) occurs, the significant changes to the current situation are likely to be:
- an increase in mean sea level, giving higher tailwater levels for the Karuah River at Karuah;
- a change in rainfalls, either on an annual or daily basis.
The prevailing ocean level at a future flood will be increased if predicted climate change impacts occur. The latest IPCC Report (Fourth Impact Assessment, 2007, Reference 21) projects a number of sea level increases over the period 1980/1990 to 2090/2099 for various scenarios of continuing “greenhouse” gas emissions. The smallest ocean increase (IPCC Scenario B1) is 0.18 m to 0.38 m over the projectionperiod. The largest increase (IPCC Scenario A1, F1) is 0.26 metres to 0.59 metres over the projection period plus a possible addition of 0.1 to 0.2 metres following warming of ice sheets.
The CSIRO and Bureau of Meteorology report following the IPCC Fourth Impact Assessment Report (Ref. 21), (Reference 22), outlines projected changes to rainfall over the project period for various regions of Australia. There is a wide range of predictions relating to the emission scenario, projection period and model used.
Over the Karuah catchment, the Technical Report (Reference 22, Chapter 5) indicates that the change in intense precipitation (measured by daily rainfall itself over 24 hours) varies for summer and autumn between -1 percent and +2 percent. Given that the uncertainty of rainfall over the catchment is significantly higher than the predicted climate change by this reference, an appropriate response for this study is to maintain the existing daily rainfall intensity data and to account for rainfall changes through application of freeboard to design flood levels.
The Department of Environment and Climate Change has issued a guideline “Practical Consideration of Climate Change”, October 2007 (Reference 22), which opines a sea level increase of 0.91, comprising 0.79 metres derived from the IPCC Reports together with a component of 0.12 metres derived bya CSIRO study as a regional sea level rise variation along the NSW coast due to changes in the East Australian ocean current. Reference 22 also opines a potential change in extreme daily rainfall for the Hunter region as a –7 percent to +10 percent change from current values. The reference also recommends sensitivity analysis for rainfall increases of 10, 20 and 30 percent from current values.
The NSW Government has recently issued a “NSW Sea Level Rise Policy Statement” which indicates planning bench marks that indicate a mean sea level rise (from 1990 mean sea levels) of 40 centimetres by 2050 and 90 centimetres by 2100.
The bulk of the Karuah River experiences flooding from runoff. In the previous chapter, “Sensitivity Analysis”, design analysis is undertaken for a 20 percent increase in river flows. This case, presented on
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Figures 26 and 27, is similar to the impact of an increase in rainfall of 20 percent. Rainfall increases of this magnitude will produce increases in flood levels between 0.7 metres and 1.2 metres upstream of Allworth, and some 0.7 metres downstream of Allworth (ignoring any increase in ocean water levels).
In the lower parts of the Karuah River, there are several possible scenarios for the combination of flooding caused by rainfall over the catchment or elevated ocean levels.
As with the design floods, tailwater scenarios have been examined:
- for future river flooding; and - for future ocean flooding
The appropriate tailwater levels adopted are:
For future river flooding, the maximum tailwater in Port Stephens at Karuah of RL 1.96 mAHD, (tailwater level for river flooding plus climate change induced increase in ocean level) comprising:
- current mean sea level: RL 0.0 m AHD - astronomical tidal variation: 0.9 metres - tidal amplification and friction losses from - Karuah to the ocean: 0.16 metres - sea level rise: 0.9 metres (as outlined in text above) Total: 1.96 metres
By similar logic, the ocean flooding scenario after climate change induced changes in ocean level would reach RL 2.81 m AHD, comprising:
- current 1% AEP level, Port Stephens: RL 1.91 m AHD - sea level rise: 0.9 metres Total: 2.81 metres
Figure 27 shows that an increase in the ocean level with river flooding will increase design flood levels in the Karuah River upstream of Karuah to Allworth.
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9. PROVISIONAL FLOOD HAZARD AND HYDRAULIC CATEGORY ANALYSIS
Figures 29 to 40 inclusive in this report indicate provisional flood hazard through the study area for the 5% AEP, 1% AEP and 0.5% AEP floods plus the Probable Maximum Flood.
The flood hazard maps were produced in accordance with the NSW Governments “Floodplain Development Manual Appendix L” and have been prepared for any future floodplain management studies.
As noted earlier, the design flood levels in this report have been derived from a MIKE-11 hydraulic model. The model is configured as a single river, and thus flood levels at the nominated points need to be transferred across the flood surface to reach the extent of inundation.
The flood hazard maps for each design event were produced using the following steps:
- ground levels were derived as the average levels over each 10 metre square fromAerial Laser Survey (ALS) data. The ALS data produces about four million data points per square kilometre. The averaging process used reduces the number of points to a more manageable 10,000 points per square kilometre (totalling some 470,000 points over the study area).
- the individual design flood surfaces were created by extrapolation of the MIKE-11 results to the approximate flood extents;
- the flood liable areas were divided into: - Flood fringe areas; - Flood storage areas; - Floodways (as the remainder of the flood extent less flood fringe and flood storage areas).
- the flood liable areas were also divided into Low Hazard, Medium Hazard and High Hazard in accordance with Appendix L, Figure L2 of the Manual (Reference 3);
- the flood hazard maps were created by combining the flood fringe, flood storage and floodways with the hydraulic categories (from Figure L2 of Reference 3) with respect to the above;
- flood fringe areas were defined (for the purposes of this study) as area where flood depths were less than 0.3 metres. In reality, this test showed very few areas would be classified as “flood fringe” within the 10 metre square grid used for the analysis.
- flood storage areas were identified by inspection of the hydraulic hazard, Flood storage was treated as flood areas definitely away from flood flowpaths or as areas of “backwater flooding”;
- floodway areas are thus identified as the remaining flood liable areas after removal of flood fringe and obvious flood storage.
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It is noted that, given the approach to identify flood levels over a relatively long area using widely spaced cross-sections (undertaken to reduce overall project cost), definition of smallfloodways using the floodway blockage definition in the Floodplain Development Manual is not possible.
In using the attached flood hazard maps:
- users should be aware of the potential deviations due to the ALS data thinning and the necessary extension of flood surfaces.
- in areas where a more precise definition of flood hazard is required, ground truthing and finer scale definition of flood extents should be undertaken on a case to case basis.
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REFERENCES
1. Institution of Engineers Australia, "Australian Rainfall and Runoff, A Guide to Flood Estimation", 1988
2. DIPNR, "PINNEENA, NSW Surface Water Archive", 2004 (Version 8)
3. New South Wales Government "Floodplain Development Manual", April 2005
4. Commonwealth Bureau of Meteorology "The Estimation of Probable Maximum Precipitation in Australia: Generalised Short-Duration Method", June 2003
5. Cordrey & Webb, “Flood Estimation in Eastern New South Wales, A Design Method”, Institution of engineers Australia, Vol CE16, No. 1, 1974
6. Institution of Engineers Australia, “Australian Rainfall and Runoff, Flood Analysis and Design”, 1977
7. Water Resources Commission, “Stroud Flood Study Report”, June 1986 (Report W2767)
8. Manly Hydraulics Laboratory, “Port Stephens Flood Study, Design Water Levels and Wave Climate”, July 1996
9. Manly Hydraulics Laboratory, “Port Stephens Flood Study – Stage 3 Foreshore flooding”, October 1997
10. Webb McKeown & Associates Pty Ltd, “Port Stephens Foreshore (Floodplain) Management Study”, April 2002
11. Water Conservation and Irrigation Commission “Water Resources of the Lower Hunter Valley” Report No. 4, August 1966
12. Bureau of Meteorology “Guide Book to the Estimation of Probable Maximum Precipitation – Generalised South East Australia Method”, October 2006
13. Bureau of Meteorology “Guidebook to the Estimation of Probable Maximum Precipitation – Generalised Tropical Storm Method”, November 2003.
14. Bureau of Meteorology “The Estimation of Probable Maximum Precipitation in Australia – Generalised Short Duration Method”, June 2003
15. Hunter District Water Board “Report on the January 1976 Flood”, Investigation Section – Water March 1976.
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REFERENCES (Cont.)
16. Hunter District Water Board “Report on the March 1977 Flood”, Investigation Section – Water, May 1977.
17. Hunter District Water Board, “Report on the March 1978 Flood”, Investigation Section – Water, November 1978.
18. Lord & Kulmar “The 1974 Storms Revisited, 25 Years Experience in Ocean Wave Measurement”, Coastal Engineering Conference, Sydney, 2000
19. Dunn, Nielson, Madsen and Evans, “Wave Setup at River Entrances”, Coastal Engineering Conference, Sydney, 2000
20. AWACS Pty Ltd, “Design Guidelines for Water Level and Wave Climate, Pittwater”, 1991
21. International Panel on Climate Change, “Fourth Impact Assessment Report”, 2007
22. CSIRO and BOM, “Climate Change in Australia, Technical Report”, 2007
23. Department of Environment and Climate Change, “Practical Consideration of Climate Change”, October 2007
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GLOSSARY - Terms and Abbreviations annual exceedance probability (AEP) the chance of a flood of a given or larger size occurring in any one year, usually expressed as a percentage. For example, if a peak flood discharge of 500 m3/s has an AEP of 5%, it means that there is a 5% chance (that is one-in-20 chance) of a peak flood discharge of 500 m3/s or larger occurring in any one year (see average recurrence interval). annual flood series is comprised of the highest instantaneous rate of discharge in each year of record. The highest flow in each year is selected, whether it is a major flood or not, and all other floods are neglected.
Australian Height Datum (AHD) a common national surface level datum approximately corresponding to mean sea level. average annual damage (AAD) depending on its size (or severity), each flood will cause a different amount of flood damage to a flood prone area. AAD is the average damage per year that would occur in a nominated development situation from flooding over a very long period of time. average recurrence interval (ARI) the long-term average number of years between the occurrence of a flood as big as, or larger than, the selected event. For example, floods with a discharge as great as, or greater than, the 20 year ARI flood event will occur on average once every 20 years. ARI is another way of expressing the likelihood of occurrence of a flood event. This is the inverse of AEP and does not reflect the time elapsed between floods.
Floodplain Management Manual the management of flood liable land development is defined in Part 4 of the Environmental Planning and Assessment Act (EP&A Act). disaster plan (DISPLAN) a step by step sequence of previously agreed roles, responsibilities, functions, actions and management arrangements for the conduct of a single or series of connected emergency operations, with the object of ensuring the coordinated response by all agencies having responsibilities and functions in emergencies. discharge the rate of flow of water measured in terms of volume per unit time, for example, cubic metres per second (m3/s). Discharge is different from the speed or velocity of flow, which is a measure of how fast the water is moving for example, metres per second (m/s).
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GLOSSARY - Terms and Abbreviations (Cont) ecologically sustainable development (ESD) using, conserving and enhancing natural resources so that ecological processes, on which life depends, are maintained, and the total quality of life, now and in the future, can be maintained or increased. A more detailed definition is included in the Local Government Act 1993. The use of sustainability and sustainable in this manual are related to ESD. effective warning time the time available after receiving advice of an impending flood and before the floodwaters prevent appropriate flood response actions being undertaken. The effective warning time is typically used to move farm equipment, move stock, raise furniture, evacuate people and transport their possessions. flash flooding flooding which is sudden and unexpected. It is often caused by sudden local or nearby heavy rainfall. Often defined as flooding which peaks within six hours of the causative rain. flood fringe areas the remaining area of flood prone land after floodway and flood storage areas have been defined. flood liable land is synonymous with flood prone land (ie) land susceptible to flooding by the probable maximum flood (PMF) event. Note that the term flood liable land now covers the whole of the floodplain, not just that part below the flood planning level, as indicated in the 1986 Floodplain Development Manual (see flood planning area). flood mitigation standard the average recurrence interval of the flood, selected as part of the floodplain risk management process that forms the basis for physical works to modify the impacts of flooding. floodplain area of land which is subject to inundation by floods up to and including the probable maximumflood event, that is, flood prone land. flood plan (local) a sub-plan of a disaster plan that deals specifically with flooding. They can exist at State, Division and local levels. Local flood plans are prepared under the leadership of the State Emergency Service. flood planning levels (FPLs) are the combinations of flood levels and freeboards selected for planning purposes, as determined in floodplain risk management studies and incorporated in floodplain risk management plans. The concept of flood planning levels supersedes the "standard flood event" of the 1986 edition of the Floodplain Development Manual.
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GLOSSARY - Terms and Abbreviations (Cont) flood prone land is land susceptible to flooding by the probable maximum flood (PMF) event. Flood prone land is synonymous with flood liable land. flood risk potential danger to personal safety and potential damage to property resulting from flooding. The degree of risk varies with circumstances across the full range of floods. Flood risk in this manual is divided into 3 types, existing, future continuing risks. They are described below. existing flood risk: the risk a community is exposed to as a result of its location on the floodplain. future flood risk: the risk a community may be exposed to as a result of new development on the floodplain. continuing flood risk: the risk a community is exposed to after floodplain risk management measures have been implemented. For a town protected by levees, the continuing flood risk is the consequences of the levees being overtopped. For an area without any floodplain risk management measures, the continuing flood risk is simply the existence of its flood exposure. flood storage areas those parts of the floodplain that are important for the temporary storage of floodwaters during thepassage of a flood. The extent and behaviour of flood storage areas may change with flood severity, and loss of flood storage can increase the severity of flood impacts by reducing natural flood attenuation. Hence, it is necessary to investigate a range of flood sizes before defining flood storage areas. floodway areas those areas of the floodplain where a significant discharge of water occurs during floods. They are often aligned with naturally defined channels. Floodways are areas that, even if only partially blocked, would cause a significant redistribution of flood flow, or a significant increase in flood levels. freeboard a factor of safety typically used in relation to the setting of floor levels, levee crest levels, etc. It is usually expressed as the difference in height between the adopted flood planning level and the flood used to determine the flood planning level. Freeboard provides a factor of safety to compensate for uncertainties in the estimation of flood levels across the floodplain, suchand wave action, localised hydraulic behaviour and impacts that are specific event related, such as levee and embankment settlement, and other effects such as "greenhouse" and climate change. Freeboard is included in the flood planning level.
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GLOSSARY - Terms and Abbreviations (Cont) hazard a source of potential harm or a situation with a potential to cause loss. In relation to this manual the hazard is flooding which has the potential to cause damage to the community. hydraulics term given to the study of water flow in waterways; in particular, the evaluation of flow parameters such as water level and velocity. hydrograph a graph which shows how the discharge or stage/flood level at any particular location varies with time during a flood. hydrology term given to the study of the rainfall and runoff process; in particular, the evaluation of peak flows, flow volumes and the derivation of hydrographs for a range of floods. local overland flooding inundation by local runoff rather than overbank discharge from a stream, river, estuary, lake or dam
Manual or Floodplain Development Manual The New South Wales Government publication "Floodplain Development Manual", 1986 mathematical/computer models the mathematical representation of the physical processes involved in runoff generation and stream flow. These models are often run on computers due to the complexity of the mathematical relationships between runoff, stream flow and the distribution of flows across the floodplain. partial flood series consists of all floods with peak discharges above a selected base value, regardless of the number of such floods occurring each year. peak discharge the maximum discharge occurring during a flood event. probable maximum flood (PMF) the largest flood that could conceivably occur at a particular location, usually estimated from probable maximum precipitation. Generally, it is not physically or economically possible to provide complete protection against this event. The PMF defines the extent of flood prone land, that is, the floodplain. The extent, nature and potential consequences of flooding associated with the PMF event should be addressed in a floodplain risk management study.
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GLOSSARY - Terms and Abbreviations (Cont) probable maximum precipitation (PMP) the greatest depth of precipitation for a given duration meteorologically possible over a given size storm area at a particular location at a particular time of the year, with no allowance made for long-term climatic trends (World Meteorological Organisation, 1986). It is the primary input to the estimation of the probable maximum flood. probability a statistical measure of the expected chance of flooding (see annual exceedance probability). profile a graph showing the flood stage at any given location along a water surface profile watercourse at a particular time rating table a relationship between flood level (as measured by gauge height) and flood flows, usually derived using actual flow measurements
Reduced Level (RL) a measured height above Australian Height Datum risk chance of something happening that will have an impact. It is measured in terms of consequences and likelihood. In the context of the manual it is the likelihood of consequences arising from the interaction of floods, communities and the environment. runoff the amount of rainfall which actually ends up as streamflow, also known as rainfall excess. stage equivalent to "water level". Both are measured with reference to a specified datum. stage hydrograph a graph that shows how the water level at a particular location changes with time during a flood. It must be referenced to a particular datum. wind fetch the horizontal distance in the direction of wind over which wind waves are generated.
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GLOSSARY - Terms and Abbreviations (Cont)
Organisations
BOM: Bureau of Meteorology
GLC: Great Lakes Council
DECC: Department of Environment and Climate Change
DLWC: Department of Land and Water Conservation
DIPNR: Department of Infrastructure Planning and Natural Resources
DMR: Department of Main Roads
DWE: Department of Water and Energy
DWR: Department of Water Resources
HDWB: Hunter District Water board
IPCC: International Panel on Climate Change
MHL: Manly Hydraulics Laboratory
PWD: NSW Public Works Department
RTA: Roads and Traffic Authority
SES: State Emergency Service
WC&IC: Water Conservation and Irrigation Commission
WRC: Water Resources Commission
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FIGURES
Great Lakes Council Karuah River Flood Study Final Report - November 2010 R90\07012.V8 . GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY
NSW
Walcha Oxley TAMWORTH KEMPSEY
H ighway Nundle PORT MACQUARIE Wauchope Kew Murrurundi
New Wingham Taree Scone Gloucester y Wa w s y t H t
e
k c Tuncurry u
Muswellbrook B ic Forster if E c n a g P l Stroud an Dungog d Buladelah
Singleton Karuah Hwy MAITLAND Nelson Bay Cessnock Hexham Wollombi NEWCASTLE
Legend Study Catchment Roads Towns
10 APR 2008 FIGURE 1 DISK REF: 07012 FIG REF: 07012_1_STUDY LOCALITY_V1 STUDYLOCALITY IERF 7022CATCHMENT_V1 012_2_C 07 REF: FILE 7012 0 REF: DISC 2007 AUG 6
To Gloucester
K a r u a h R i v e r
W
a
r
d
s
R
i
v y e a ery r gh er W Tele Riv y Johns m ons ts m e a ck M u B To Taree
M
R Kar i uah l i River l v e C
r r
e
e
k
Stroud Road
reek tion C m Sta ek Ra re s C an m La Stroud Bulahdelah
k To Dungog ee Cr ey k rl ee de r Al C al or Bo Booral C as ey s C re ek r ve Ri Allworth
L h i
m c n e a b r u B r e n h e T r s Cr eek ay w gh Hi ic cif Pa
Karuah AUHRVRFODSTUDY FLOOD RIVER KARUAH
To Raymond Terrace
Port Stephens RA AE COUNCIL LAKES GREAT TD CATCHMENT STUDY
Legend
IUE2 FIGURE 0 5 10 Catchment Boundary Scale (kilometres) Roads IERF 7023RANAL STNS.V2 AINFALL_ 012_3_R 07 REF: FILE 7012 0 REF: DISC 2008 OCT 27 To Gloucester 60033
60003
K a 60062 r u a h R 60042 60148 iv e 60143 r 61350
W
a
r
d
60008 s
R
i
v
y e a ery r gh er W Tele Riv 61340 61151 y Johnsons m 60089 60096 61332 ts m e a k c M u B 61045 61170 M K R aru i ah R l i iver l v 61302 C e r r
e 61122 e k To Taree
Stroud Road 61106 61169 61364 eek on Cr Stati k Ram ee Cr ns 61267 ma La 61227 61071 Stroud Bulahdelah 60002
k To Dungog ee Cr y k rle ee 61002 de r Al C al 61361 61184 or Bo Booral Ca sey s C ree 61160 61059 k er iv R Allworth
L
61339 i h 61038 m c n e a 61349 b r u B r e n h 61010 e T r s Cr eek y 61096 wa 61076 gh Hi fic 61250 ci Pa
Karuah 61072 60123 61405 To Raymond Terrace
Port Stephens 61035 61283 'Mallabula' 'Tomaree' 61303 61054 61046 61281 61395 STUDY FLOOD RIVER KARUAH
61034
61311 Legend COUNCIL LAKES GREAT
ANALSTATIONS RAINFALL Catchment Boundary 61078 Pluviometer Station 61379 Daily Rainfall Station Current, commenced before 1930 Current, commenced after 1930 and before 1980 Tidal water level Station (MHL) IUE3 FIGURE
61390 0 5 10 Scale (kilometres) GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY (209002) OO Pikes Crossing Pikes RR Mammy Johnsons River - River Johnsons Mammy (209004) K Stroud Road Stroud PP Mammy Johnsons River - River Johnsons Mammy TT M QQ GG L KK BB UU P N SS EE HH LL VV CC DD O AAA Q JJ II V NN AA FF U Z WW T S J MM R ZZ Y X I YY H W XX F (209003) G E Karuah River - Booral - River Karuah 10 B D PP (209008) (209018) 5 (209001) Karuah River - Stroud Road Stroud - River Karuah A Scale (km) Scale Karuah River - Dam Site Dam - River Karuah C Karuah River - Monkerai - River Karuah 0 Legend River Gauging Station Gauging River RORB Model junction Subcatchment Subcatchment boundary Subcatchment Subcatchment Identifier Catchment Catchment Boundary RORB storages
15 AUG 2008 FIGURE 4 DISC REF: 07012 FILE REF: 07012_4_RORB_LAYOUT.V2 RORB MODEL LAYOUT GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY
Karuah River at Booral - March 1977 Karuah River at Booral - March 1978 (Gauging Station 209003) (Gauging Station 209003) 0900 hrs, 1 March1977 0000 hrs, 18 March 1978 Start time: Start time: 2000.0 2000.0
1500.0 1500.0 Modelled
Recorded Modelled
1000.0 1000.0 Recorded Discharge (cu. m/s) Discharge (cu. m/s)
500.0 500.0
0.0 0.0 0.0 50.0 100.0 150.0 0.0 50.0 100.0 150.0 Duration (hours) Duration (hours)
28 March 2008 FIGURE 5 DISC REF: 07012 FILE REF: 07012_5_COMP_1977&1978 FLOODS_V3 C0MPARISON - 1977 & 1978 FLOODS GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Karuah River at Booral - February 1990 (Gauging Station 209003) Start time: 0000 hrs, 2 February 1990 2000.0
Modelled (RORB)
1500.0
Recorded
1000.0 Discharge (cu. m/s)
500.0
0.0 0.0 50.0 100.0 150.0 Duration (hours)
8 APRIL 2008 DISC REF: 07012 FIGURE 6 FILE REF: 07012_6_COMP_1990 FLOODS_V3 COMPARISON - 1990 FLOOD GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Karuah River at Dam Site #3 - May 2001 Karuah River at Booral - May 2001
Start time: (Gauging Station 209018) Start time: (Gauging Station 209003) 0000 hrs, 5 May 2001 0000 hrs, 5 May 2001 2000.0 2000.0
1500.0 1500.0
Recorded Modelled (RORB)
1000.0 1000.0 Discharge (cu. m/s) Discharge (cu. m/s) Recorded
Modelled (RORB)
500.0 500.0
0.0 0.0 0.0 50.0 100.0 150.0 0.0 50.0 100.0 150.0 Duration (hours) Duration (hours)
8 APRIL 2008 FIGURE 7 DISC REF: 07012 FILE REF: 07012_7_COMP_2001 FLOOD_V3 COMPARISON (RORB Results) - 2001 FLOOD GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY
Karuah River at Booral - June 2007 (Gauging Station 209003) 0900 hrs, 7 June 2007 Start time: 2000.0
1500.0
1000.0 Modelled Discharge (cu. m/s)
500.0
Recorded
0.0 0.0 50.0 100.0 150.0 Duration (hours)
10 September 2008 FIGURE 8 DISC REF: 07012 FILE REF: 07012_8_COMP_2007 FLOOD_V1 COMPARISON - 2007 FLOOD GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY
Recurrence Interval (years) 10000.0 2 5 10 20 50 100 200
e 5000.0 c en d fi on 4000.0 c 5% + 3 Log Pearson 3 distribution P 3000.0 L
RORB with design rainfall (No areal reduction) 2000.0 GEV distribution
LP3 -5% confidence
Adopted RORB with design rainfall (0.9 areal reduction factor) 1000.0 Discharge (cu. m/s)
Legend Historical Floods
100.0 50 20 10 5 2 1 0.5 Annual Exceedence Probability (% AEP)
FIGURE 9 7 JUNE 2008 DISK REF: 07012 FLOOD FREQUENCY, KARUAH RIVER AT BOORAL FIG REF: 07012_9_FLOOD_FREQ_KARUAH_@BOORAL_V5 GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY
2000.0 2000.0 2000.0
The Branch
Mammy Johnsons River @ Stroud Road 1500.0 1500.0 1500.0
Karuah River @ Stroud Road
1000.0 1000.0 1000.0 Discharge (cu. m/s) Discharge (cu. m/s) Discharge (cu. m/s) Mill & Lamans Creeks Limeburners Creek Casey's Creek
Ram Station Creek 500.0 500.0 500.0 Alderley Creek
0.0 0.0 0.0 0.0 50.0 100.0 0.0 50.0 100.0 0.0 50.0 100.0 Duration (hours) Duration (hours) Duration (hours)
Note: Hydrographs produced from calibrated RORB catchment model 15 AUGUST 2008 FIGURE 10 DISC REF: 07012 FILE REF: 07012_10_TRIB INFLOWS_1%AEP,36HR_V3 TRIBUTARY INFLOWS - 1% AEP STORM, 36 HOUR DURATION GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY
5000.0
Karuah at Old Pacific Highway, Karuah 4000.0
Karuah River at Booral
3000.0
2000.0 Discharge (cu. m/s)
1000.0
0.0
0.0 50.0 100.0 Duration (hours)
Note: Hydrographs produced from calibrated RORB catchment model FIGURE 11 22 AUGUST 2008 DISK REF: 07012 KARUAH RIVER FLOWS - 1%AEP STORM, 36 HR DURATION FIG REF: 07012_11_FLOWS_1%AEP, 36HR_V3 GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY
15000 15000
Karuah River at Booral Karuah at Old Pacific Highway, Karuah PMF 24 hour
10000 10000 PMF 24 hour
5000 5000 Discharge (cu. m/s) Discharge (cu. m/s) Design 1% AEP
Design 1% AEP
0.0 0.0
0.0 50.0 100.0 0.0 50.0 100.0 Duration (hours) Duration (hours)
22 AUGUST 2008 FIGURE 12 DISC REF: 07012 FILE REF: 07012_12_PMFVS1%AEP_V3 KARUAH RIVER - COMPARISON 1% AEP TO PMF GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY
B Karuah River at Booral o Station: 209003 o ra l C Stroud r e e k A ld er
l K17 ey M C Booral K16 ill re
C K9 e k K19 re K10 ek K11 K8 K18 K7 iver K15 K12
K6 R K13
M K5 am #7 ruah my Ka J K14 ohn son s Ri ver Karuah River at Booral Karuah River at Stroud K3 Stroud Road K4.5 K2 r #3 #4 ve #5 Ri #1 #6 uah K1 #2 Kar To Gloucester K4 Karuah River at Washpool Karuah River at Stroud Road
Karuah River at North Coast Railway Ram Station Ck
Legend Location Karuah River at Stroud Cross-section K11 Flood Level (resident interview, see Table 10) #1
0 5 T o D u Scale (Km) n g o 28 OCTOBER 2008 g FIGURE 13 DISC REF: 07012 FILE REF: 07012_13_LOCATION CROSS-SECTIONS - UPPER_V3 LOCATION OF CROSS-SECTIONS - UPPER GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY T o T a r 0 5 e e
Scale (Km)
Pacific Highway
T h e B ra n c h B o o ra l C re e Karuah By-pass k K28 K27 K23 K22 K17 #8 K19 K21 K24 K20 K25 K18 K18 Karuah River Karuah River at Pacific Highway
Allworth K26
Karuah River at Karuah By-pass k e e r C s r e n r u b e im L Legend Location Karuah River at Stroud Cross-section K11 Flood Level (resident interview, see Table 10) #1
To Ra ym on d T er ra ce
28 OCTOBER 2008 FIGURE 14 DISC REF: 07012 FILE REF: 07012_14_LOCATION CROSS-SECTIONS_LOWER_V3 LOCATIONOFCROSS-SECTIONS-LOWER GREATLAKESCOUNCIL KARUAH RIVER FLOOD STUDY 5885.1 Low level bridge, Stroud HDWB #2 peak level RTA Bridge, Booral & DECC gauge Low level bridge, Stroud Road RTA Bridge, Dungog - Stroud Road 13973.0 HDWB #4 peak level 2026.0 Railway Bridge, Stroud Road 4702.0 HDWB#1 peak level HDWB#3 peak level Boat Ramp, Allworth Karuah By-pass Pacific Highway, Karuah 18512.0 HDWB #5 peak level 20119.0 36548.0 41237.0 "Karuah" Karuah River, Port Stephens 3655.0 17702.0 43364.0 25512.0 31542.0 47013.0 5918.0 5956.1 3353.O 12414.0 12478.0 The Branch Casey Creek Karuah River 21948.0 21901.9 Alderley Creek Ram Station Creek Limeburners Creek Mammy Johnsons R See Detail Mill & Lahman Creek See Detail See Detail "Booral_2" Approach Bridge Bridge Structure 0.0
"Washpool_upass" 40.0 "Stroud_rail_ubridge" "Booral_1" Approach Bridge Bridge Structure 0.0 0.0 0.0 490.0 40.0 393.0
"Booral_br" RTA bridge Bridge Structure RTA Bridge Bridge Structure Railway Bridge Bridge Structure Cattle U'pass Culvert Structure Approach Spans Culvert Structure "Stroud_rail" "Washpool_br" 0.0 120.0 "Karuah" 0.0 0.0 120.0 120.0
"Karuah" "Karuah" 3634.0 3717.0 6224.0 5473.0 5928.0 5986.0 3449.0 3634.0 3717.0 3809.0 Approaches Weir Structure FIGURE 15 8 May 2008 Rail Embank. Approaches
DISK REF: 07012 Weir Structure Weir Structure FILE REF: 07012_15_MIKE-11_LAYOUT_V2 MIKE-11 MODEL LAYOUT GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Tailwater Level, Port Stephens - March 1977 Tailwater Level, Port Stephens - March 1978 +1.0 +1.0 0000 hrs, 18 March 1978 Start time: 0900 hrs, 1 March 1977 0.0 0.0 Water level (m AHD) Water level (m AHD)
-1.0 -1.0 Start time:
0.0 50.0 100.0 150.0 0.0 50.0 100.0 150.0 Duration (hours) Duration (hours)
Tailwater Level, Port Stephens - February 1990 Tailwater Level, Port Stephens - May 2001 +1.0 +1.0 Start time: 0000 hrs, 05 May 2001 0.0 0.0 Water level (m AHD) Water level (m AHD)
-1.0 Start time:0000 hrs, 02February 1990 -1.0 0.0 50.0 100.0 150.0 0.0 50.0 100.0 150.0 Duration (hours) Duration (hours) 16 September 2009 FIGURE 16 DISC REF: 07012 FILE REF: 07012_16_HISTORICAL_WATER_LEVELS_SHT1_V3 HISTORICAL WATER LEVELS, PORT STEPHENS_SHEET 1 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Tailwater Level, Port Stephens - June 2007 +1.0 0000 hrs, 07 June 2007 Start time:
0.0 Water level (m AHD)
-1.0 0.0 50.0 100.0 150.0 Duration (hours)
FIGURE 17
16 September 2009 HISTORICAL WATER LEVELS, PORT STEPHENS_SHEET 2 DISC REF: 07012 FILE REF: 07012_17_HISTORICAL_WATER_LEVELS, PORT STEPHENS_SHT2_V3 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
15.0
1990 Modelled Flood 10.0 Rating Curve (excludes overbank flows) (Based on DWE curve and actual gaugings) Height (m AHD) 5.0
0.0 1000 2000 3000 4000 5000
Flow (cu m/sec)
FIGURE 18
26 October 2009 COMPARISON MODEL RESULTS vs BOORAL RATING CURVE DISK REF: 07012 FIG REF: 07012_18_BOORAL QvsH_1990_V3 LEGEND GREAT LAKES COUNCIL 1977 Flood KARUAH RIVER FLOOD STUDY 1978 Flood 2007 Flood Design 1% AEP Flood 1977 Flood Mark 1978 Flood Mark 2007 Flood Mark Bridge Structures Flood Marks from Structures
60 Confluence, Mammy Johnsons River Washpool Bridge Stroud Bridge Confluence, Mill Creek Booral Bridge Confluence, Booral Creek HDWB #5 Bridge - Stroud Road Confluence, Ramstation Creek HDWB #2 HDWB #3 Confluence, Alderley Creek HDWB #4 Rail Bridge, Stroud Road HDWB #1
50
40
30 Height (m AHD)
20
10
0 K14 K17 K19 K1 K2 K3 K4 K4.5 K5 K6 K7 K8 K9 K10 K11 K12 K13 K15 K16 K18 -10 0 5 10 15 20 25 Distance (kilometres)
26 OCTOBER 2009 FIGURE 19 DISK REF: 07012 FILE REF: 07012_19_HISTORICAL_FLOOD_PROF_KARUAH_RIVER - UPPER_V5 HISTORICAL FLOOD PROFILES - KARUAH RIVER - UPPER GREAT LAKES COUNCIL LEGEND KARUAH RIVER FLOOD STUDY 1977 Flood 1978 Flood 2007 Flood Design 1% AEP Flood 1977 Flood Mark 1978 Flood Mark 2007 Flood Mark
Flood Marks from Structures
30 Allworth - Upstream HDWB #6 Confluence, The Branch HDWB #5 Boat Ramp, Allworth Confluence, Limeburners Creek Karuah Bridge, Pacific Highway Karuah By-Pass
25
20
15 Height (m AHD)
10
5
0 K19 K21 K22 K23 K24 K25 K26 K27 K28 K20
-10 25 30 35 40 45 50 Distance (kilometres)
26 OCTOBER 2009 FIGURE 20 DISK REF: 07012 FILE REF: 07012_20_HIST_FLOOD_PROFILES,KARUAH_ RIVER_ LOWER_V5 HISTORICAL FLOOD PROFILES - KARUAH RIVER - LOWER GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
20.0 RTA Bridge "Karuah River @ Booral"
Deck @ Booral Creek
15.0 DECC record, Stn 209003 HDWB peak level indicators RORB / MIKE-11 calculated levels
Abut. top Station 209003
1894 Top of Bank
1971 1990 10.0 1985 1978 1990 1978 Legend 2007 1978
Flood Level (m AHD) 1987 1977 2007 1977 2001 DECC records 2001 1977 HDWB records
1976 1976 RTA Bridge Details
5.0 Calculated flood levels Bed Levels
"Cease to Flow" level Gauge zero Bed Level 0.0
Notes: This diagram indicates the flood levels at Booral as retrieved from three historical sources. 26 OCT 2009 FIGURE 21 DISK REF: 07012 FIG REF: 07012_21_COMPARISON OF LEVELS, KARUAH AT BOORAL_V3 COMPARISON OF FLOOD LEVELS, KARUAH RIVER @ BOORAL GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Design Tailwater , Port Stephens at Karuah 3.00
Design Tailwater , River Flooding plus Climate Change 2.00 Design Tailwater , Current Ocean Flooding
1.00
0.00 Water Level ( mAHD) Design Tailwater , Current River Flooding -1.00
0.0 10.0 20.0 30.0 40.0 50.0 60.0
Time (hrs)
FIGURE 22
26 OCT 2009 DISK REF: 07012 DESIGN TAILWATER LEVELS , KARUAH FIG REF: 07012_22_DESIGN_TAILWATER, KARUAH_V2 LEGEND GREAT LAKES COUNCIL PMF Flood 0.5% AEP Flood KARUAH RIVER FLOOD STUDY 1% AEP Flood 2% AEP Flood 5% AEP Flood 10% AEP Flood 20% AEP Flood 50% AEP Flood Bridge Structures my Johnsons River ud Road ral Creek
60 Confluence, Mam Washpool Bridge Stroud Bridge Confluence, Mill Creek Booral Bridge Confluence, Boo HDWB #5 Bridge - Stroud Road Confluence, Ramstation Creek HDWB #2 HDWB #3 Confluence, Alderley Creek HDWB #4 Rail Bridge, Stro HDWB #1
50
40
30 Height (m AHD)
20
10
0 K1 K2 K3 K4 K4.5 K5 K6 K7 K8 K9 K10 K11 K12 K13 K14 K15 K16 K17 K18 K19 -10 0 5 10 15 20 25 Distance (kilometres)
26 October 2009 FIGURE 23 DISK REF: 07012 FILE REF: 07012_23_DESIGN_FLOOD_PROF_KARUAH_RIVER - UPPER_V5 DESIGN FLOOD PROFILES - KARUAH RIVER - UPPER GREAT LAKES COUNCIL LEGEND PMF Flood KARUAH RIVER FLOOD STUDY 0.5% AEP Flood 1% AEP Flood 2% AEP Flood 5% AEP Flood 10% AEP Flood 20% AEP Flood 50% AEP Flood Bridge Structures
30 Allworth - Upstream Boat Ramp, Allworth HDWB #6 Confluence, The Branch HDWB #5 Confluence, Limeburners Creek Karuah Bridge, Pacific Highway Karuah By-Pass
25
Flood levels affected by Port Stephens (2% AEP and bigger) 20
15 Height (m AHD)
10
5
0 K19 K21 K22 K23 K24 K25 K26 K27 K28 K20
-10 25 30 35 40 45 50 Distance (kilometres)
18 January 2010 FIGURE 24 DISK REF: 07012 FILE REF: 07012_24_DESIGN_FLOOD_PROFILES, KARUAH_ RIVER- LOWER_V5 DESIGN FLOOD PROFILES - KARUAH RIVER - LOWER GREAT LAKES COUNCIL LEGEND PMF Flood KARUAH RIVER FLOOD STUDY 0.5% AEP Flood 1% AEP Flood 2% AEP Flood 5% AEP Flood 10% AEP Flood 20% AEP Flood 50% AEP Flood Bridge Structures Allworth - Upstream HDWB #6 Confluence, The Branch HDWB #5 Boat Ramp, Allworth Confluence, Limeburners Creek Karuah Bridge, Pacific Highway Karuah By-Pass
Flood levels affected 5.0 by Port Stephens (50% AEP and bigger)
4.0
3.0 Height (m AHD)
2.0
1.0
0 K19 K21 K22 K23 K24 K25 K26 K27 K28 K20
25 30 35 40 45 Distance (kilometres)
19 Jan 2010 FIGURE 25 DISK REF: 07012 FILE REF: 07012_25_DESIGN_FLOOD_PROFILES, KARUAH_ RIVER_NEAR_KARUAH_V3 DESIGN FLOOD PROFILES - KARUAH RIVER NEAR KARUAH LEGEND GREAT LAKES COUNCIL 1% AEP at peak of tide KARUAH RIVER FLOOD STUDY 1%AEP at trough of tide 1% AEP plus greenhouse 1% AEP Discharge factored by 1.2 1% AEP Friction factored by 1.2 Bridge Structures my Johnsons River ud Road ral Creek
60 Confluence, Mam Washpool Bridge Stroud Bridge Confluence, Mill Creek Booral Bridge Confluence, Boo HDWB #5 Bridge - Stroud Road Confluence, Ramstation Creek HDWB #2 HDWB #3 Confluence, Alderley Creek HDWB #4 Rail Bridge, Stro HDWB #1
50
40
30 Height (m AHD)
20
10
0 K15 K1 K2 K3 K4 K4.5 K5 K6 K7 K8 K9 K10 K11 K12 K13 K14 K16 K17 K18 K19 -10 0 5 10 15 20 25 Distance (kilometres)
26 October 2009 FIGURE 26 DISK REF: 07012 FILE REF: 07012_26_SENSITIVITY_TESTING_KARUAH_RIVER - UPPER_V3 SENSITIVITY TESTING - KARUAH RIVER - UPPER GREAT LAKES COUNCIL
LEGEND KARUAH RIVER FLOOD STUDY 1% AEP at peak of tide 1%AEP at trough of tide 1% AEP plus greenhouse 1% AEP Discharge factored by 1.2 1% AEP Friction factored by 1.2 Bridge Structures Allworth - Upstream HDWB #6 Confluence, The Branch HDWB #5 Boat Ramp, Allworth Confluence, Limeburners Creek Karuah Bridge, Pacific Highway Karuah By-Pass
12.5
10 Height (m AHD)
5
Port Stephens with 0.92 increase Port Stephens with tide, storm surge, wind set-up
0 K19 K21 K22 K23 K24 K25 K26 K27 K28 K20 -2.5 25 30 35 40 45 50 Distance (kilometres)
21 January 2010 FIGURE 27 DISK REF: 07012 FILE REF: 07012_27_SENSITIVITY PROFILES,KARUAH_ RIVER_ LOWER_V4 SENSITIVITY TESTING - KARUAH RIVER - LOWER GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Building on Floodplain
PMF flood level (RL 33.24 m AHD) Design 1% AEP flood level (RL 27.47 m AHD) Design 2% AEP flood level (RL 26.85 m AHD) Highest flood, resident report (RL 26.63 m AHD)
2007 flood level (RL 23.02 m AHD)
Bed (approx RL 16.6 m AHD)
Mean Sea Level ( 0.0 m AHD)
Typical flood levels, Karuah River near Stroud
FIGURE 28
26 October 2009 DIAGRAMMATIC REPRESENTATION, FLOOD LEVELS DISK REF: 07012 FIG REF: 07012_28_DIAGRAM_FLOOD_LEVELS_V2 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Stroud A ld Flood liability extends towards Stroud er For detail, see Stroud Flood Study l F ey L C
0 r 2 . ee 4 3 k
. 2 0 .0 L 22 F FL M i .0 ll 21 F C F r F r L e L e L F Riv L ek ah 2 2 aru 2 7 6 K . . 8 0 0 . F F 0 L L F L 1 3 r 9 0 . 2 e 0 9 v . i 0 . R 0 ah F F aru L L K 2 2 5 0 . . F 0 0 Ma L 3 mm 1.0 y Jo Karuah River at Stroud hns ons Ri ver F L FL 39.0 3 4 .0 FL 32.0 Legend Stroud Road .0 38 L F F L 3 3.0 Area not flooded by Karuah River To Gloucester er F iv L R 3 Floodway - Low Hazard h F a F 5 ru L .0 a L K F 3 4 L 6 0 . . 3 0 FL 0 Floodway - Medium Hazard 41 7 .0 . 0 Karuah River at Stroud Road Floodway - High Hazard Karuah River at North Coast Railway Karuah River at RTA bridge "Washpool" Flood storage - Low Hazard T o Ram Station Ck D u n Flood storage - Medium Hazard g o g Flood storage - High Hazard
0 1 2 3 4 5 10 FEB 2010 FIGURE 29 DISC REF: 07012 FILE REF: 07012_29_PROV_ HAZARD_5%AEP_SH1_V2 Kilometres PROVISIONAL FLOOD HAZARD 5% AEP - SHEET 1 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
h a l e d e l u
B
o
T
B
o
o
r
a .0 l To C S r .0 FL4 t 0 ro A e 0 u 1 . d l e d Karuah River at Booral L 9 e k F rl Station: 209003 ey L Cr F e F e 0 k L . 0 . 1 7 7 Booral 1 1 0 . L r . 0 e F F 6 v L L i 1 0 R
0 F . 1 FL 18.0 . 2 h L 5 0 a 9 .0 . F 1 u F 1 6 L r 5.0 r L a L
L e K v F F i 0 F R . h 8 a L Allworth ru F iver a K h R K ar rua ua Ka h R Legend iv er 0 . FL 13.0 4 Area not flooded by Karuah River 1
L
F Karuah River at Booral Floodway - Low Hazard
Floodway - Medium Hazard
T o Pa Floodway - High Hazard cific High way Flood storage - Low Hazard
Flood storage - Medium Hazard
Flood storage - High Hazard 0 1 2 3 4 5 16 FEB 2010 FIGURE 30 DISC REF: 07012 FILE REF: 07012_30_PROV. HAZARD_5%AEP_SHT 2_V2 Kilometres PROVISIONAL FLOOD HAZARD 5% AEP - SHEET 2 Legend GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY Area not flooded by Karuah River
Floodway - Low Hazard
Floodway - Medium Hazard e e
r
a
T Floodway - High Hazard o T
Flood storage - Low Hazard
T h e Flood storage - Medium Hazard B r a n c h Flood storage - High Hazard
P
T aci
h f e ic
B H
r igh a
s n s w c a a h p y - y
B
h 6 FL3.0 5 a 7 . u 1 FL2. r L a
F K
5 .
3
L
F iver ah R Karu
Allworth aruah River T K River o Karuah R a ym on d T errace
FL2.0
0 1 2 3 4 5 16 FEB 2010 FIGURE 31 DISC REF: 07012 FILE REF: 07012_31_PROV. HAZARD_5%AEP_SHT 3_V2 Kilometres PROVISIONAL FLOOD HAZARD 5% AEP - SHEET 3 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Stroud A ld Flood liability extends towards Stroud er For detail, see Stroud Flood Study l ey 0 C . r 4 ee F 2 k
L L 2 5 F 0 .0 M FL23. il l C
0 er . r 0 e iv
. R
8 e h
9 k a
2 ru
2 Ka L
FL27.0
L
F F
0 . F
1 FL30.0 L 3 er v F 2 L i L 1 R 2 F F . ah 6 0 . L ru 0 Ka 2 2
. 0 Ma mm y J FL32. Karuah River at Stroud ohn 0 son 0 s R . ive 0 r 4 L F FL33.0 Stroud Road Legend FL41.0 F F L3 Area not flooded by Karuah River L F 4. 42 L 0 To Gloucester .0 r 35 ve .0 Ri F h L Floodway - Low Hazard a F 3 ru 6 a L . K 3 0 F .0 7 L . 39 0 3 FL 8 Floodway - Medium Hazard . Karuah River at Stroud Road 0
Karuah River at North Coast Railway Floodway - High Hazard Karuah River at RTA bridge "Washpool"
T Flood storage - Low Hazard o Ram Station Ck D u n g o Flood storage - Medium Hazard g
Flood storage - High Hazard
0 1 2 3 4 5 5 FEB 2010 FIGURE 32 DISC REF: 07012 FILE REF: 07012_32_PROV. HAZARD_1%AEP_SH1_V2 Kilometres PROVISIONAL FLOOD HAZARD 1% AEP - SHEET 1 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
h a l e d e l u
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Floodway - High Hazard T o Pa cific High Flood storage - Low Hazard way
Flood storage - Medium Hazard
Flood storage - High Hazard
0 1 2 3 4 5 5 FEB 2009 FIGURE 33 DISC REF: 07012 FILE REF: 07012_33_PROV. HAZARD_1%AEP_SH2_V2 Kilometres PROVISIONAL FLOOD HAZARD 1% AEP - SHEET 2 Legend GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY Area not flooded by Karuah River Floodway - Low Hazard
Floodway - Medium Hazard e e
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Flood storage - Low Hazard
T h e Flood storage - Medium Hazard B r a n c h Flood storage - High Hazard
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0 1 2 3 4 5 5 FEB 2009 FIGURE 34 DISC REF: 07012 FILE REF: 07012_34_PROV. HAZARD_1%AEP_SH3_V2 Kilometres PROVISIONAL FLOOD HAZARD 1% AEP - SHEET 3 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Stroud
Flood liability extends towards Stroud Al de For detail, see Stroud Flood Study rl ey C
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Ma F mm L y J 33 Karuah River at Stroud ohn .0 son s R F ive L r 3 5 .0 F L 0.0 4 4 1 .0 FL Stroud Road F Legend L3 F 4. L 0 4 F 2 Area not flooded by Karuah River L .0 F To Gloucester 4 L 3. 3 0 er 6 iv .0 R F Floodway - Low Hazard ah L u 3 r F a 7 K L . 3 0
8
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T Flood storage - Low Hazard o Ram Station Ck D u n g Flood storage - Medium Hazard o g Flood storage - High Hazard
0 1 2 3 4 5 10 FEB 2010 FIGURE 35 DISC REF: 07012 Kilometres FILE REF: 07012_35_PROV. HAZARD_0.5%_SH1_V2 PROVISIONAL FLOOD HAZARD 0.5% AEP - SHEET 1 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
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6 1 Area not flooded by Karuah River
L
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Floodway - Medium Hazard
Floodway - High Hazard
To P acific Hig Flood storage - Low Hazard hway
Flood storage - Medium Hazard
Flood storage - High Hazard 0 1 2 3 4 5 10 FEB 2010 FIGURE 36 DISC REF: 07012 FILE REF: 07012_36_PROV. HAZARD_0.5%AEP_SH2_V2 Kilometres PROVISIONAL FLOOD HAZARD 0.5% AEP - SHEET 2 Legend GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY Area not flooded by Karuah River
Floodway - Low Hazard
Floodway - Medium Hazard e e
r
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0 1 2 3 4 5 12 FEB 2010 FIGURE 37 DISC REF: 07012 FILE REF: 07012_37_PROV. HAZARD_0.5%AEP_SH3_V2 Kilometres PROVISIONAL FLOOD HAZARD 0.5% AEP - SHEET 3 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
Stroud
Al de rl Flood liability extends towards Stroud ey For detail, see Stroud Flood Study Cr
0 e . ek 0 9 .
2 2
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F L Area not flooded by Karuah River 3 To Gloucester 8 FL46.0 . 0 r ive R 0 . Floodway - Low Hazard h ua 0 r 4
a 0 . FL47.0 K L
0 1
. F 4
2 L 4 Floodway - Medium Hazard 0
. F
L 3 Karuah River at Stroud Road 4 F L
F Karuah River at North Coast Railway Floodway - High Hazard Karuah River at RTA bridge "Washpool" Flood storage - Low Hazard T o Ram Station Ck D u n g Flood storage - Medium Hazard o g Flood storage - High Hazard
0 1 2 3 4 5 12 FEB 2010 FIGURE 38 DISC REF: 07012 FILE REF: 07012_38_PROV. HAZARD_PMF_SH1_V2 Kilometres PROVISIONAL FLOOD HAZARD PMF - SHEET 1 GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY
h a l e d e l u
B
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T
B FL10.0 o o To ra St 0 l r . oud Al C d Karuah River at Booral 8 r FL17.0 e 1 e rl Station: 209003 e ey L k C F r 0 0 e . . e 5
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0 L 0 5
.
L 4 F 4
. Booral L 2 1 r 9 1 F 2 .0
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L
F Karuah River at Booral Floodway - Low Hazard
Floodway - Medium Hazard
Floodway - High Hazard T o Pa cific High Flood storage - Low Hazard way
Flood storage - Medium Hazard
Flood storage - High Hazard 0 1 2 3 4 5 15 FEB 2010 FIGURE 39 DISC REF: 07012 Kilometres FILE REF: 07012_39_PROV. HAZARD_PMF_SH2_V2 PROVISIONAL FLOOD HAZARD PMF - SHEET 2 Legend GREAT LAKES COUNCIL KARUAH RIVER FLOOD STUDY Area not flooded by Karuah River
Floodway - Low Hazard
Floodway - Medium Hazard e e
r
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T Floodway - High Hazard o T
Flood storage - Low Hazard
T h e Flood storage - Medium Hazard B r a n c h Flood storage - High Hazard
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FL5.5
FL 6.0 FL6 .5
0 1 2 3 4 5 12 FEB 2010 FIGURE 40 DISC REF: 07012 FILE REF: 07012_40_PROV. HAZARD_PMF_SH3_V2 Kilometres PROVISIONAL FLOOD HAZARD PMF - SHEET 3 Paterson Consultants Pty Limited
APPENDICES
Great Lakes Council Karuah River Flood Study Final Report - November 2010 R90\07012.V8 . Paterson Consultants Pty Limited
APPENDIX A
ANNUAL FLOOD SERIES, STATION 209003 “KARUAH RIVER AT BOORAL”
Great Lakes Council Karuah River Flood Study Final Report - November 2010 R90\07012.V8 . Paterson Consultants Pty Limited
APPENDIX A
Annual Flood Series, Station 209003 “Karuah River at Booral” Recorded Yearly Peak – Karuah River at Booral
Date 1 Peak Flow Peak Height Annual Rank Q (ML/day) Q (cu m/sec) G H (m) m AHD
21-Jun-69 93,900 1,087 7.16 8.21 11 09-Dec-70 17,500 203 3.68 4.73 33 3 21-Jan-71 209,400 2,423 9.30 10.35 1 25-Jan-72 2 100,800 1,167 7.31 8.36 9 3 08-Dec-73 18,500 214 3.79 4.84 31 3 04-Jun-74 63,800 739 6.21 7.26 18 21-Jun-75 58,700 679 6.01 7.06 20 02-Mar-76 81,900 948 6.81 7.86 14 04-Mar-77 101,300 1,173 7.33 8.38 8 20-Mar-78 130,100 1,506 7.98 9.03 5 06-May-79 23,200 268 4.17 5.22 29 10-May-80 7,100 82 2.59 3.64 37 04-Apr-81 7,700 89 2.68 3.73 36 12-Oct-82 31,600 366 4.73 5.78 27 27-May-83 8,500 99 2.80 3.85 35 07-Nov-84 69,100 799 6.43 7.48 16 13-Oct-85 180,400 2,088 8.86 9.91 2 24-Jan-86 37,900 439 5.10 6.15 24 12-Nov-87 105,300 1,219 7.48 8.53 7 06-Jul-88 56,200 650 5.97 7.02 21 27-Apr-89 45,400 526 5.48 6.53 22 04-Feb-90 163,300 1,890 8.60 9.65 3 11-Jun-91 17,800 206 3.74 4.79 32 3 09-Feb-92 33,400 387 4.84 5.89 26 3
Great Lakes Council Appendix A Karuah River Flood Study Page A1 Final Report - November 2010 R90 \07012.V8 Paterson Consultants Pty Limited
Date 1 Peak Flow Peak Height Annual Rank Q (ML/day) Q (cu m/sec) G H (m) m AHD
05-Aug-93 7,000 81 2.59 3.64 38 28-Feb-94 2,700 32 1.78 2.83 39 03-Jan-95 25,000 289 4.29 5.34 28 3 06-May-96 13,700 159 3.37 4.42 34 06-Mar-97 35,800 414 4.99 6.04 25 18-Nov-98 58,200 674 6.05 7.10 19 15-Jul-99 89,700 1,038 7.07 8.12 13 22-Mar-00 95,900 1,109 7.09 8.14 12 08-May-01 122,000 1,412 7.87 8.92 6 05-Feb-02 41,300 479 5.18 6.23 23 27-May-03 73,500 851 6.43 7.48 17 23-Mar-04 94,400 1,093 7.20 8.25 10 23-Mar-05 77,400 896 6.60 7.65 15 06-Nov-06 21,000 243 3.96 5.01 30 3 08-Jun-07 151,300 1,751 8.42 9.47 4 3 Notes: 1. 39 yearsofrecord, from 1969 to 2007 inclusive. 2007 has been included because it was significant, despite theyearnot beingcomplete 2. Records indicate a peak annualGHof 6.71 m at 9amon 24/06/1972 but this wasexceeded in January 1972 aslistedabove 3. Flows forthese floodevents(in Ml/day) were read by Paterson Consultants from rating tables.All otherflows were suppliedbyDWE.
Great Lakes Council Karuah River Flood Study Appendix A Final Report - November 2010 Page A2 R90\07012.V8 Paterson Consultants Pty Limited
APPENDIX B
DAILY RAINFALL STATIONS AND PLUVIOMETER STATIONS
Great Lakes Council Karuah River Flood Study Final Report - November 2010 R90\07012.V8 . Paterson Consultants Pty Limited
APPENDIX B-1 DAILY RAINFALL STATIONS
North East Bom_id Name Start Finish
-32.70 151.60 061035 MAITLAND WEST 1858 1953 -32.71 152.16 061054 NELSON BAY (NELSON HEAD) 1881 -32.72 151.62 061046 MORPETH POST OFFICE 1884 -32.40 151.75 061227 DUNGOG (COOREII) 1886 1919 -32.66 152.01 061072 TAHLEE (CARRINGTON HOUSE) 1887 -32.40 151.96 061071 STROUD POST OFFICE 1889 -32.58 151.78 061010 CLARENCE TOWN (GREY ST) 1895 -32.40 151.75 061017 DUNGOG POST OFFICE 1897 -32.60 151.61 061096 PATERSON POST OFFICE 1901 -32.50 151.80 061059 PINE BRUSH 1902 1953 -32.74 151.58 061034 EAST MAITLAND BOWLING CLUB 1902 1994 -32.41 152.20 060002 BULAHDELAH POST OFFICE 1905 -32.09 152.24 060033 KRAMBACH - BELLEVUE 1908 -32.25 151.68 061332 DUNGOG (WANGAT) 1912 1920 -32.70 151.76 061283 EAGLETON 1912 1924 -32.28 151.83 061045 MONKERAI UPPER (REDLEAF) 1914 1970 -32.11 152.20 060003 BULBY BRUSH - BLUE LOOK-OUT 1925 -32.55 151.80 061339 CLARENCETOWN (MILL DAM FALLS (WILLIAMS R 1927 -32.56 151.60 061349 GOSTWYCK BRIDGE (PATERSON RIVER) 1929 -32.55 151.60 061038 MARTINS CREEK 1933 1945 -32.45 152.10 061022 GIRVAN STATE FOREST 1936 1959 -32.30 151.75 061302 CHICHESTER STATE FOREST 1938 1958 -32.61 151.88 061076 RAYMOND TERRACE (WALLAROO STATE FOREST) 1938 -32.20 152.31 060009 COOLONGALOOK STATE FOREST 1938 1970 -32.20 151.90 060008 CRAVEN STATE FOREST 1938 1956
Great Lakes Council Karuah River Flood Study Appendix B Final Report - November 2010 Page B1 R90\07012.V8 Paterson Consultants Pty Limited
North East Bom_id Name Start Finish
-32.24 151.68 061151 CHICHESTER DAM 1942 -32.39 151.76 061267 DUNGOG (WILLIAMS RIVER) 1949 -32.50 151.65 061160 HILLDALE POST OFFICE 1960 1976 -32.36 151.63 061169 GRESFORD (DURHAM PARK) 1960 1988 -32.28 151.79 061170 DUNGOG - MAIN CREEK (YERANDA) 1960 -32.46 151.86 061184 MARSHDALE (RAGLAN) 1960 1976 -32.31 151.71 061122 DUNGOG (TILLEGRA) 1960 1986 -32.15 151.95 060042 CRAVEN (LONGVIEW) 1961 -32.13 152.08 060062 WAUKIVORY (THE RANCH) 1961 -32.62 151.59 061250 PATERSON (TOCAL AWS) 1967 -32.56 151.60 061258 MARTINS CREEK (GOSTWYCK HOUSE) 1967 1971 -32.25 151.98 060089 WARDS RIVER (MOANA) 1968 1979 -32.46 151.68 061361 DUNGOG (WALLARINGA) 1968 1998 -32.23 151.85 061340 WARDS RIVER (MEROO) 1970 1977 -32.71 152.06 061303 SALAMANDER BAY (WARATAH AVE) 1971 -32.67 152.17 060123 HAWKS NEST (LANGI ST) 1981 -32.17 151.59 061350 UPPER CHICHESTER (SIMMONDS) 1981 -32.36 151.68 061364 DUNGOG (LEAWOOD) 1981 -32.16 152.25 060143 DYERS CROSSING (WANG WAUK ROAD) 1995 1996 -32.73 152.01 061395 TANILBA BAY WWTP 2001 -32.35 151.80 061106 DUNGOG (MONKERAI HILL (URIMBIRRA)) 2001 -32.44 152.15 060099 CRAWFORD RIVER (CRAWFORD) 2002 -32.25 152.12 060096 CABBAGE TREE MOUNTAIN 2002 -32.29 152.30 060065 WOOTTON 2002 -32.16 152.26 060148 WILLINA 2003 -32.73 152.02 061281 WILLIAMTOWN (NEWCASTLE RADAR) 2003 -32.67 151.62 061405 WOODVILLE ( CLARENCE TOWN RD ) 2004
Great Lakes Council Karuah River Flood Study Appendix B Final Report - November 2010 Page B2 R90\07012.V8 Paterson Consultants Pty Limited
APPENDIX B-2 PLUVIOMETER STATIONS
North East Bom_id Name Start Finish
-32.91 151.75 61223 MARYVILLE Jan 1964 Sep 1991 -32.89 151.70 61390 NEWCASTLE UNIVERSITY Jul 1998 Jan 2003 -32.80 151.84 61379 WILLIAMTOWN COMPARISON AWS Jun 1998 Sep 1999 -32.79 151.83 61078 WILLIAMTOWN RAAF Dec 1952 Jan 2003 -32.76 151.79 61311 GRAHAMSTOWN (HUNTER WATER BOARD) Jan 1975 Feb 2003 -32.62 151.59 61250 PATERSON (TOCAL AWS) Jan 1975 Apr 2003 -32.24 151.68 61151 CHICHESTER DAM Jun 1960 Jun 2003
Great Lakes Council Karuah River Flood Study Appendix B Final Report - November 2010 Page B3 R90\07012.V8
Paterson Consultants Pty Limited
APPENDIX C
DESIGN RAINFALLS – INTENSITY-FREQUENCY-DURATION
Great Lakes Council Karuah River Flood Study Final Report - November 2010 R90\07012.V8 . *** OUTPUT IFD TABLE ***
Rainfall Intensity (mm/h) for Karuah inland
______
Duration Average Storm Recurrence Interval (years)
1 2 5 10 20 50 100 ______
(hour) 1 24.7 31.8 40.64 45.89 52.91 62.22 69.41 1.25 21.79 28.13 36.19 41.02 47.44 55.99 62.61 1.5 19.64 25.4 32.88 37.37 43.33 51.29 57.47 2 16.63 21.59 28.2 32.21 37.5 44.6 50.12 3 13.13 17.12 22.66 26.06 30.52 36.53 41.25 4 11.09 14.52 19.39 22.41 26.35 31.69 35.9 5 9.73 12.77 17.18 19.93 23.51 28.39 32.23 6 8.74 11.5 15.56 18.12 21.43 25.94 29.51 8 7.39 9.76 13.32 15.59 18.51 22.52 25.7 10 6.49 8.59 11.81 13.87 16.53 20.18 23.09 12 5.83 7.74 10.71 12.61 15.07 18.45 21.15 14 5.39 7.15 9.85 11.58 13.81 16.88 19.33 16 5.04 6.67 9.16 10.76 12.81 15.63 17.88 18 4.75 6.27 8.6 10.07 11.98 14.6 16.68 20 4.5 5.94 8.11 9.5 11.28 13.73 15.68 22 4.28 5.65 7.7 9 10.68 12.99 14.81 24 4.09 5.39 7.34 8.57 10.16 12.34 14.06 36 3.3 4.33 5.84 6.78 8 9.67 10.98 48 2.81 3.68 4.92 5.7 6.7 8.06 9.14 60 2.47 3.23 4.29 4.94 5.8 6.96 7.87 72 2.21 2.88 3.81 4.38 5.13 6.13 6.92 ______*** OUTPUT IFD TABLE ***
Rainfall Intensity (mm/h) for Karuah coast
______
Duration Average Storm Recurrence Interval (years)
1 2 5 10 20 50 100 ______
(hour) 1 24.58 31.89 41.75 47.66 55.4 65.7 73.66 1.25 21.66 28.11 36.81 42.03 48.86 57.94 64.97 1.5 19.51 25.33 33.16 37.86 44.02 52.21 58.54 2 16.51 21.43 28.07 32.05 37.27 44.2 49.57 3 13.01 16.89 22.13 25.27 29.39 34.87 39.1 4 10.98 14.26 18.68 21.34 24.81 29.44 33.02 5 9.63 12.5 16.38 18.71 21.76 25.82 28.96 6 8.65 11.23 14.72 16.81 19.55 23.2 26.02 8 7.3 9.48 12.43 14.2 16.52 19.6 21.99 10 6.41 8.32 10.91 12.46 14.5 17.21 19.3 12 5.76 7.47 9.8 11.2 13.03 15.47 17.35 14 5.25 6.82 8.97 10.26 11.95 14.2 15.94 16 4.84 6.3 8.3 9.51 11.08 13.19 14.82 18 4.51 5.87 7.75 8.88 10.37 12.35 13.88 20 4.23 5.51 7.28 8.36 9.77 11.64 13.1 22 3.99 5.2 6.89 7.91 9.25 11.03 12.42 24 3.78 4.93 6.54 7.52 8.8 10.5 11.83 36 2.93 3.83 5.12 5.91 6.93 8.31 9.38 48 2.42 3.17 4.27 4.94 5.81 6.98 7.89 60 2.08 2.72 3.68 4.27 5.03 6.06 6.86 72 1.82 2.39 3.24 3.77 4.45 5.36 6.08 ______Paterson Consultants Pty Limited
APPENDIX D
DESIGN FLOOD LEVELS
Great Lakes Council Karuah River Flood Study Final Report - November 2010 R90\07012.V8 . Paterson Consultants Pty Ltd
APPENDIX D
DESIGN FLOOD LEVELS
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 2025.54 Start of model 2025.5 37.48 39.32 40.21 41.12 42.04 42.72 43.34 47.00
KARUAH 2275.35 37.33 39.16 39.98 40.85 41.71 42.35 42.97 46.61
KARUAH 2525.17 K1 2525.2 37.17 38.91 39.72 40.55 41.33 41.91 42.50 46.13
KARUAH 2756.00 37.07 38.76 39.55 40.35 41.11 41.68 42.25 45.93
KARUAH 2986.83 36.98 38.77 39.40 40.17 40.93 41.50 42.05 45.77
KARUAH 3217.66 36.91 38.53 39.27 40.04 40.78 41.34 41.88 45.63
Low level bridge, 3353.0 Stroud Road
KARUAH 3448.49 36.85 38.53 39.27 39.92 40.65 41.20 41.74 45.50
KARUAH 3634.00 36.80 38.37 39.27 39.84 40.55 41.10 41.64 45.42
Bridge, North Coast 3655.0
APPENDIX D Great Lakes Council Page D1 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP Rail, Stroud Road
KARUAH 3717.60 36.66 38.21 38.90 39.61 40.24 40.73 41.20 44.75
KARUAH 3731.72 K2 3731.7 36.66 38.20 38.90 39.60 40.23 40.72 41.19 44.74
KARUAH 3808.88 36.63 38.74 38.86 39.56 40.19 40.67 41.13 44.70
KARUAH 4022.69 36.57 38.10 38.77 39.46 40.07 40.54 40.99 44.59
KARUAH 4236.50 36.51 38.02 38.69 39.37 39.95 40.42 40.88 44.50
KARUAH 4450.31 36.45 37.95 38.61 39.28 39.86 40.32 40.78 44.43
KARUAH 4664.12 36.29 37.78 38.42 39.10 39.66 40.12 40.58 44.26
Confluence, Mammy 4702.4 Johnsons Creek
KARUAH 4877.93 K3 4877.9 35.80 37.27 37.90 38.61 39.15 39.64 40.13 43.93
KARUAH 5076.30 35.53 36.96 37.55 38.30 38.84 39.37 39.87 43.78
KARUAH 5274.67 35.31 36.68 37.26 38.08 38.62 39.15 39.67 43.64
KARUAH 5473.04 35.11 36.44 37.02 37.91 38.43 38.98 39.50 43.51
APPENDIX D Great Lakes Council Page D2 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 5632.06 34.97 36.27 36.87 37.79 38.29 38.84 39.36 43.36
KARUAH 5791.09 K4 5791.1 34.84 36.09 36.67 37.62 38.08 38.62 39.13 43.11
Confluence, 5885.1 Ramstation Creek
KARUAH 5916.20 34.70 35.88 36.44 37.37 37.83 38.37 38.88 42.81
HDWB_Level #1 5918.1
KARUAH 5927.28 34.73 35.90 36.44 37.35 37.82 38.35 38.86 42.79
High Level RTA 5956.1 bridge, "Washpool"
KARUAH 5986.20 34.66 35.82 36.34 37.22 37.67 38.17 38.64 42.12
KARUAH 5996.20 34.62 35.78 36.30 37.18 37.63 38.14 38.61 42.09
KARUAH 6223.95 34.38 35.43 35.92 36.75 37.19 37.69 38.15 41.61
KARUAH 6454.32 34.09 35.07 35.54 36.33 36.75 37.24 37.70 41.13
KARUAH 6684.69 33.77 34.69 35.15 35.91 36.32 36.80 37.25 40.67
APPENDIX D Great Lakes Council Page D3 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 6915.06 33.44 34.32 34.76 35.50 35.89 36.37 36.82 40.21
KARUAH 7145.44 33.10 33.93 34.36 35.08 35.46 35.93 36.37 39.76
KARUAH 7375.81 32.71 33.51 33.94 34.64 35.02 35.48 35.92 39.32
KARUAH 7606.18 K4.5 7606.2 32.24 33.05 33.47 34.16 34.54 35.00 35.44 38.87
KARUAH 7837.37 31.67 32.52 32.95 33.66 34.04 34.50 34.95 38.42
KARUAH 8068.55 31.10 31.98 32.44 33.16 33.55 34.02 34.47 37.98
KARUAH 8299.74 30.50 31.42 31.93 32.66 33.07 33.54 34.00 37.57
KARUAH 8530.92 29.86 30.87 31.41 32.18 32.60 33.08 33.54 37.18
KARUAH 8762.11 29.19 30.34 30.90 31.72 32.16 32.65 33.11 36.80
KARUAH 8993.29 28.56 29.83 30.42 31.29 31.74 32.24 32.71 36.47
KARUAH 9224.48 27.99 29.35 29.98 30.90 31.37 31.88 32.35 36.17
KARUAH 9455.66 27.47 28.93 29.61 30.56 31.04 31.55 32.03 35.91
KARUAH 9686.85 27.03 28.58 29.30 30.27 30.76 31.27 31.74 35.68
APPENDIX D Great Lakes Council Page D4 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 9918.03 26.69 28.32 29.05 30.03 30.53 31.03 31.50 35.48
KARUAH 10149.22 K5 10149.2 26.43 28.12 28.86 29.84 30.34 30.84 31.31 35.31
KARUAH 10327.72 26.19 27.90 28.65 29.64 30.14 30.64 31.11 35.15
KARUAH 10506.23 K6 10506.2 25.93 27.59 28.32 29.27 29.78 30.28 30.76 34.88
KARUAH 10730.04 25.65 27.26 27.94 28.86 29.37 29.85 30.34 34.62
KARUAH 10953.84 25.36 26.92 27.56 28.48 28.98 29.47 29.97 34.39
KARUAH 11177.65 25.06 26.56 27.18 28.11 28.61 29.12 29.64 34.18
KARUAH 11401.46 24.74 26.19 26.81 27.77 28.27 28.80 29.33 34.00
KARUAH 11625.27 24.38 25.82 26.45 27.45 27.95 28.51 29.05 33.84
KARUAH 11849.07 23.98 25.46 26.11 27.16 27.65 28.24 28.80 33.69
KARUAH 12072.88 K7 12072.9 23.50 25.11 25.79 26.89 27.39 28.00 28.57 33.56
KARUAH 12319.94 22.95 24.67 25.40 26.57 27.07 27.69 28.28 33.37
Low level Bridge, 12413.7
APPENDIX D Great Lakes Council Page D5 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP Stroud
HDWB_Level #2 12478.4
KARUAH 12567.00 22.48 24.21 24.97 26.23 26.72 27.35 27.95 33.16
KARUAH 12814.07 22.09 23.74 24.52 25.86 26.35 26.98 27.58 32.90
KARUAH 13061.13 K8 13061.1 21.77 23.27 24.07 25.47 25.95 26.58 27.18 32.61
KARUAH 13296.59 21.45 22.92 23.72 25.17 25.63 26.26 26.87 32.40
KARUAH 13532.06 21.11 22.59 23.41 24.94 25.38 26.01 26.62 32.25
KARUAH 13767.53 20.77 22.30 23.16 24.77 25.19 25.82 26.43 32.16
Confluence, Mill 13973.3 Creek
KARUAH 14002.99 K9 14003.0 20.42 22.04 22.94 24.59 25.02 25.65 26.26 32.03
KARUAH 14239.54 19.81 21.56 22.54 24.27 24.71 25.34 25.95 31.80
KARUAH 14476.10 19.11 20.86 21.88 23.84 24.31 24.92 25.52 31.49
KARUAH 14712.65 K10 14712.7 18.18 19.99 20.98 23.05 23.58 24.23 24.87 31.08
APPENDIX D Great Lakes Council Page D6 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 14929.29 17.37 19.31 20.31 22.40 22.95 23.77 24.47 30.83
KARUAH 15145.93 16.71 18.76 19.76 21.89 22.45 23.35 24.16 30.63
KARUAH 15362.57 16.16 18.28 19.33 21.49 22.04 23.01 23.90 30.47
KARUAH 15579.20 15.70 17.89 18.99 21.17 21.72 22.74 23.68 30.34
KARUAH 15795.84 15.35 17.57 18.71 20.91 21.47 22.53 23.50 30.24
KARUAH 16012.48 15.08 17.34 18.49 20.72 21.28 22.36 23.36 30.16
KARUAH 16229.12 K11 16229.1 14.89 17.16 18.31 20.56 21.13 22.24 23.24 30.10
KARUAH 16460.50 14.68 16.95 18.11 20.35 20.90 22.00 23.00 29.94
KARUAH 16691.87 14.47 16.75 17.90 20.12 20.66 21.76 22.76 29.70
KARUAH 16923.25 14.26 16.53 17.68 19.88 20.41 21.50 22.49 29.37
HDWB_Level #3 17401.5
KARUAH 17154.62 14.03 16.30 17.45 19.63 20.14 21.22 22.20 29.01
KARUAH 17386.00 13.81 16.05 17.20 19.35 19.84 20.91 21.88 28.63
APPENDIX D Great Lakes Council Page D7 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 17617.37 13.57 15.79 16.93 19.05 19.52 20.56 21.52 28.20
KARUAH 17848.75 13.32 15.50 16.63 18.73 19.17 20.18 21.12 27.71
KARUAH 18080.12 13.06 15.17 16.30 18.36 18.77 19.75 20.66 27.14
KARUAH 18311.50 12.77 14.81 15.92 17.95 18.32 19.26 20.13 26.48
Confluence, Alderley 18512.6 Creek
KARUAH 18542.88 12.42 14.37 15.43 17.38 17.72 18.62 19.44 25.49
KARUAH 18774.25 K12 18774.3 11.93 13.78 14.76 16.52 16.87 17.71 18.46 24.03
KARUAH 19014.02 11.54 13.31 14.25 15.91 16.23 16.99 17.72 23.14
KARUAH 19253.78 11.25 12.97 13.90 15.50 15.81 16.54 17.23 22.44
KARUAH 19493.54 11.08 12.76 13.65 15.17 15.47 16.18 16.84 21.94
KARUAH 19733.31 K13 19733.3 10.88 12.51 13.38 14.83 15.11 15.77 16.39 21.15
KARUAH 19949.50 10.77 12.36 13.22 14.62 14.89 15.52 16.12 20.76
APPENDIX D Great Lakes Council Page D8 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP KARUAH 20165.70 10.66 12.23 13.06 14.42 14.68 15.30 15.87 20.40
KARUAH 20381.89 10.50 12.10 12.91 14.23 14.48 15.08 15.63 20.07
KARUAH 20598.08 10.31 11.94 12.76 14.02 14.26 14.85 15.38 19.76
KARUAH 20814.27 10.04 11.68 12.54 13.79 14.03 14.58 15.10 19.45
KARUAH 21030.47 9.48 11.30 12.19 13.47 13.71 14.25 14.76 19.14
KARUAH 21246.66 K14 21246.7 8.58 10.40 11.44 12.90 13.15 13.71 14.25 18.79
KARUAH 21454.77 7.88 9.58 10.47 12.16 12.43 13.06 13.65 18.53
KARUAH 21662.89 7.51 9.03 9.87 11.39 11.68 12.40 13.05 18.32
KARUAH 21871.00 7.23 8.69 9.47 10.75 11.01 11.77 12.50 18.17
Bucketts Way bridge, 21901.9 Booral
KARUAH 21911.00 7.01 8.38 9.15 10.36 10.61 11.39 12.16 17.96
HDWB_Level #4 21948.0
KARUAH 22135.46 6.50 7.97 8.79 10.58 10.94 11.47 12.24 17.88
APPENDIX D Great Lakes Council Page D9 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 22359.92 K16 22359.9 5.87 7.44 8.44 10.30 10.65 11.20 11.98 17.72
KARUAH 22574.41 5.38 7.02 8.00 9.97 10.34 10.95 11.77 17.58
KARUAH 22788.91 5.07 6.75 7.71 9.73 10.12 10.78 11.59 17.48
KARUAH 23003.40 4.90 6.57 7.53 9.56 9.94 10.60 11.41 17.36
Confluence, Booral 23169.9 Creek
KARUAH 23217.90 4.80 6.46 7.40 9.37 9.75 10.43 11.24 17.17
KARUAH 23467.88 4.67 6.30 7.23 9.18 9.56 10.25 11.06 17.03
KARUAH 23717.87 K17 23217.9 4.52 6.12 7.06 8.99 9.37 10.08 10.89 16.89
KARUAH 23967.86 4.35 5.94 6.87 8.80 9.18 9.90 10.71 16.74
KARUAH 24217.84 4.15 5.74 6.67 8.61 8.99 9.73 10.53 16.60
KARUAH 24467.82 3.92 5.52 6.47 8.41 8.80 9.55 10.36 16.46
KARUAH 24717.81 K18 24717.8 3.64 5.28 6.25 8.21 8.61 9.37 10.18 16.31
APPENDIX D Great Lakes Council Page D10 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 24904.45 3.46 5.05 6.02 7.98 8.37 9.14 9.95 16.02
KARUAH 25091.08 3.35 4.90 5.82 7.72 8.10 8.87 9.66 15.59
KARUAH 25277.72 K19 25277.7 3.29 4.80 5.69 7.50 7.87 8.60 9.35 14.92
KARUAH 25498.39 3.20 4.66 5.54 7.30 7.66 8.38 9.13 14.62
HDWB_Level #5 25511.9
KARUAH 25719.06 3.10 4.53 5.38 7.09 7.44 8.17 8.92 14.34
KARUAH 25939.73 3.00 4.38 5.22 6.88 7.23 7.97 8.71 14.06
KARUAH 26160.39 2.89 4.23 5.04 6.68 7.03 7.78 8.51 13.79
KARUAH 26381.06 2.77 4.07 4.87 6.49 6.83 7.58 8.31 13.52
KARUAH 26601.73 2.65 3.91 4.70 6.30 6.64 7.39 8.11 13.26
KARUAH 26822.40 K20 26822.4 2.52 3.75 4.53 6.11 6.45 7.20 7.91 13.00
KARUAH 27030.07 2.41 3.59 4.37 5.94 6.27 7.02 7.72 12.75
KARUAH 27237.75 2.31 3.45 4.19 5.74 6.08 6.83 7.52 12.47
APPENDIX D Great Lakes Council Page D11 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 27445.42 2.21 3.32 4.03 5.51 5.85 6.60 7.29 12.18
KARUAH 27653.10 2.13 3.18 3.88 5.32 5.64 6.34 7.02 11.85
KARUAH 27860.77 K21 27860.8 2.05 3.06 3.72 5.13 5.43 6.12 6.75 11.47
KARUAH 28095.37 1.98 2.94 3.58 4.94 5.24 5.91 6.52 11.15
KARUAH 28329.96 1.92 2.84 3.45 4.77 5.06 5.71 6.31 10.86
KARUAH 28564.56 1.87 2.75 3.34 4.61 4.90 5.53 6.13 10.62
KARUAH 28799.16 1.83 2.67 3.23 4.47 4.75 5.37 5.97 10.40
KARUAH 29033.76 1.79 2.59 3.13 4.31 4.59 5.21 5.79 10.08
KARUAH 29268.35 1.75 2.52 3.04 4.14 4.44 5.04 5.60 9.73
KARUAH 29502.95 1.72 2.46 2.96 4.03 4.34 4.93 5.47 9.68
KARUAH 29737.55 1.69 2.41 2.89 3.95 4.25 4.82 5.35 9.66
KARUAH 29972.14 1.67 2.36 2.83 3.87 4.18 4.73 5.26 9.65
KARUAH 30206.74 1.65 2.33 2.80 3.80 4.11 4.67 5.21 9.63
APPENDIX D Great Lakes Council Page D12 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 30441.34 1.64 2.30 2.76 3.75 4.07 4.63 5.15 9.62
KARUAH 30675.94 1.62 2.28 2.74 3.73 4.04 4.60 5.14 9.61
KARUAH 30910.53 1.62 2.27 2.72 3.71 4.03 4.59 5.13 9.60
ALllworth, Upstream 31029.5
KARUAH 31145.13 K22 31145.1 1.61 2.26 2.71 3.70 4.02 4.59 5.12 9.59
KARUAH 31391.44 1.60 2.24 2.69 3.68 4.00 4.56 5.10 9.56
Boat Ramp, 31542.4 Allworth
KARUAH 31637.75 1.59 2.23 2.68 3.65 3.98 4.54 5.08 9.53
HDWB_Level #6 31740.6
KARUAH 31884.05 1.58 2.21 2.66 3.63 3.95 4.52 5.05 9.49
KARUAH 32130.36 1.57 2.19 2.64 3.60 3.93 4.49 5.02 9.46
KARUAH 32376.67 1.56 2.18 2.62 3.58 3.90 4.46 5.00 9.42
APPENDIX D Great Lakes Council Page D13 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 32622.98 1.55 2.16 2.59 3.55 3.88 4.43 4.96 9.38
KARUAH 32869.29 1.54 2.14 2.57 3.52 3.85 4.40 4.93 9.33
KARUAH 33115.59 1.53 2.12 2.55 3.48 3.82 4.37 4.90 9.28
KARUAH 33361.90 K23 33361.9 1.51 2.10 2.52 3.45 3.78 4.33 4.86 9.23
KARUAH 33599.05 1.50 2.08 2.50 3.41 3.75 4.30 4.82 9.18
KARUAH 33836.20 1.49 2.05 2.47 3.38 3.72 4.27 4.79 9.14
KARUAH 34073.36 1.48 2.03 2.45 3.35 3.69 4.23 4.75 9.09
KARUAH 34310.51 1.48 2.01 2.42 3.31 3.66 4.20 4.72 9.05
KARUAH 34547.66 1.48 1.99 2.40 3.28 3.62 4.16 4.68 9.00
KARUAH 34784.81 1.48 1.97 2.37 3.24 3.59 4.13 4.65 8.96
KARUAH 35021.96 1.48 1.95 2.35 3.20 3.56 4.10 4.61 8.91
KARUAH 35259.12 1.48 1.93 2.32 3.17 3.53 4.06 4.57 8.87
KARUAH 35496.27 K24 35496.3 1.48 1.91 2.29 3.13 3.49 4.03 4.54 8.82
APPENDIX D Great Lakes Council Page D14 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 35734.38 1.48 1.88 2.27 3.09 3.46 3.99 4.50 8.77
KARUAH 35972.48 1.48 1.86 2.24 3.05 3.42 3.95 4.45 8.71
KARUAH 36210.59 1.48 1.84 2.21 3.00 3.38 3.90 4.41 8.66
KARUAH 36448.70 1.48 1.81 2.16 2.93 3.30 3.82 4.32 8.49
Confluence, The 36548.2 Branch
KARUAH 36686.80 1.48 1.76 2.10 2.85 3.20 3.70 4.19 8.25
KARUAH 36924.91 1.48 1.73 2.06 2.79 3.14 3.63 4.11 8.14
KARUAH 37163.01 1.48 1.70 2.02 2.73 3.07 3.56 4.03 8.03
KARUAH 37401.12 1.48 1.67 1.98 2.67 3.01 3.49 3.95 7.91
KARUAH 37639.23 1.48 1.64 1.94 2.61 2.95 3.42 3.87 7.78
KARUAH 37877.33 1.48 1.62 1.91 2.56 2.89 3.35 3.79 7.65
KARUAH 38115.44 1.48 1.62 1.87 2.50 2.83 3.28 3.72 7.51
APPENDIX D Great Lakes Council Page D15 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 38353.54 1.48 1.62 1.84 2.45 2.77 3.21 3.64 7.36
KARUAH 38591.65 K25 38591.7 1.48 1.62 1.80 2.39 2.71 3.14 3.56 7.22
KARUAH 38833.48 1.48 1.62 1.78 2.36 2.68 3.11 3.53 7.17
KARUAH 39075.32 1.48 1.62 1.75 2.31 2.63 3.06 3.48 7.12
KARUAH 39317.15 1.48 1.62 1.72 2.27 2.59 3.01 3.42 7.06
KARUAH 39558.98 1.48 1.62 1.70 2.23 2.54 2.96 3.37 7.00
KARUAH 39800.82 1.48 1.62 1.70 2.18 2.50 2.90 3.31 6.92
KARUAH 40042.65 1.48 1.62 1.70 2.14 2.45 2.85 3.25 6.83
KARUAH 40284.48 1.48 1.62 1.70 2.09 2.40 2.79 3.19 6.73
KARUAH 40526.32 1.48 1.62 1.70 2.05 2.35 2.74 3.12 6.64
KARUAH 40768.15 1.48 1.62 1.70 2.01 2.30 2.68 3.06 6.54
KARUAH 41009.98 1.48 1.62 1.70 2.00 2.26 2.62 3.00 6.43
Confluence 41237.3
APPENDIX D Great Lakes Council Page D16 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP Limeburners Creek
KARUAH 41251.81 1.48 1.62 1.70 1.92 2.20 2.55 2.91 6.27
KARUAH 41493.65 1.48 1.62 1.70 1.86 2.13 2.47 2.83 6.07
KARUAH 41735.48 1.48 1.62 1.70 1.82 2.08 2.41 2.75 5.93
KARUAH 41977.31 1.48 1.62 1.70 1.78 2.03 2.35 2.67 5.78
KARUAH 42219.15 1.48 1.62 1.70 1.76 1.98 2.28 2.60 5.63
KARUAH 42460.98 K26 42461.0 1.48 1.62 1.70 1.76 1.93 2.22 2.52 5.46
KARUAH 42706.37 1.48 1.62 1.70 1.76 1.88 2.15 2.44 5.30
KARUAH 42951.76 1.48 1.62 1.70 1.76 1.83 2.09 2.36 5.14
KARUAH 43197.15 1.48 1.62 1.70 1.76 1.83 2.02 2.29 4.97
Karuah by_pass 43363.8
KARUAH 43442.54 1.48 1.62 1.70 1.76 1.83 1.95 2.21 4.80
KARUAH 43687.93 1.48 1.62 1.70 1.76 1.83 1.91 2.13 4.63
APPENDIX D Great Lakes Council Page D17 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 43933.32 1.48 1.62 1.70 1.76 1.83 1.91 2.04 4.46
KARUAH 44178.71 1.48 1.62 1.70 1.76 1.83 1.91 1.98 4.29
KARUAH 44424.11 1.48 1.62 1.70 1.76 1.83 1.91 1.98 4.11
KARUAH 44669.50 1.48 1.62 1.70 1.76 1.83 1.91 1.98 3.94
KARUAH 44914.89 1.48 1.62 1.70 1.76 1.83 1.91 1.98 3.78
KARUAH 45160.28 1.48 1.62 1.70 1.76 1.83 1.91 1.98 3.63
KARUAH 45405.67 K27 45405.7 1.48 1.62 1.70 1.76 1.83 1.91 1.98 3.50
KARUAH 45633.73 1.48 1.62 1.70 1.76 1.83 1.91 1.98 3.30
KARUAH 45861.79 1.48 1.62 1.70 1.76 1.83 1.91 1.98 3.07
KARUAH 46089.84 1.48 1.62 1.70 1.76 1.83 1.91 1.98 2.82
KARUAH 46317.90 1.48 1.62 1.70 1.76 1.83 1.91 1.98 2.52
KARUAH 46545.96 1.48 1.62 1.70 1.76 1.83 1.91 1.98 2.15
KARUAH 46774.01 1.48 1.62 1.70 1.76 1.83 1.91 1.98 1.98
APPENDIX D Great Lakes Council Page D18 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Levels (m AHD) Model Calculation Location River River (36 hour storm, flood peak co-incident with peak tide) Points Section Distance 50% 20% 10% 5% 2% 1% 0.5% (m) PMP AEP AEP AEP AEP AEP AEP AEP
KARUAH 47002.07 K28 47002.1 1.48 1.62 1.70 1.76 1.83 1.91 1.98 1.98
KARUAH 47029.36 End of model 47029.4 1.48 1.62 1.70 1.76 1.83 1.91 1.98 1.98
APPENDIX D Great Lakes Council Page D19 Karuah River Flood Study Final Report - November 2010 R90\07012.V8
Paterson Consultants Pty Limited
APPENDIX E
DESIGN FLOOD FLOWS
Great Lakes Council Karuah River Flood Study Final Report - November 2010 R90\07012.V8 . Paterson Consultants Pty Ltd
APPENDIX E
DESIGN FLOOD DISCHARGES
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
Start of model 2,025.5
KARUAH 2150.45 298 508 652 840 1,086 1,291 1,506 3,574 KARUAH 2400.26 297 508 652 839 1,084 1,289 1,504 3,572 K1 2,525.2
KARUAH 2640.58 297 627 651 839 1,083 1,288 1,502 3,570 KARUAH 2871.42 297 506 651 838 1,082 1,287 1,500 3,569 KARUAH 3102.25 297 573 651 837 1,081 1,286 1,498 3,566
KARUAH 3333.07 297 507 651 836 1,080 1,285 1,497 3,564 Low level bridge, Stroud 3,353.0 Road KARUAH 3541.25 295 1,920 1,105 2,602 1,596 1,909 2,652 3,544
KARUAH 3655.00 Low level bridge, Stroud 3,353.0 0 0 0 0 0 0 0 738
APPENDIX E Great Lakes Council Page E1 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP Road KARUAH 3724.66 295 841 1,430 1,091 1,212 1,273 1,485 3,543
K2 3,731.7 KARUAH 3770.30 295 1,011 1,665 1,397 1,357 1,273 1,485 3,543 KARUAH 3915.78 296 1,785 1,573 1,683 2,457 1,283 1,952 3,560
KARUAH 4129.60 296 1,399 1,386 1,645 1,078 1,282 1,496 3,561 KARUAH 4343.40 296 1,184 1,246 1,305 1,242 1,282 1,495 3,562 KARUAH 4557.21 296 818 1,018 1,137 1,192 1,282 1,495 3,564
Confluence, Mammy 4,702.4 Johnsons Creek KARUAH 4771.02 603 1038 1334 1710 2180 2595 3029 7132 K4 4,877.9
KARUAH 4977.12 603 1037 1333 1710 2180 2595 3028 7132 KARUAH 5175.48 603 1036 1333 1711 2180 2595 3028 7133
APPENDIX E Great Lakes Council Page E2 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP KARUAH 5373.85 603 1036 1333 1712 2181 2595 3028 7134 KARUAH 5552.55 599 1022 1315 1686 2150 2558 2990 7091
KARUAH 5711.58 599 1022 1315 1687 2150 2559 2990 7092 K4 5,791.1 KARUAH 5853.65 599 1023 1315 1688 2151 2559 2990 7092
Confluence, Ramstation 5,885.1 Creek KARUAH 5921.74 631 1080 1389 1970 2314 2755 3217 7834 KARUAH 5956.00 High Level RTA bridge, 5,956.1 0 0 0 0 0 0 0 158 "Washpool"
KARUAH 5991.20 631 1080 1389 1970 2314 2755 3217 7834 KARUAH 6110.08 631 1080 1389 1970 2314 2755 3216 7834 KARUAH 6339.14 636 1094 1408 1997 2345 2792 3255 7878
KARUAH 6569.51 636 1094 1408 1996 2345 2792 3255 7878 KARUAH 6799.88 635 1094 1408 1996 2345 2791 3255 7878
APPENDIX E Great Lakes Council Page E3 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 7030.25 635 1093 1408 1996 2344 2790 3255 7878
KARUAH 7260.62 635 1093 1408 1995 2344 2790 3254 7877 KARUAH 7490.99 635 1093 1408 1995 2343 2789 3254 7877 K4.5 7,606.2
KARUAH 7721.77 635 1093 1407 1995 2343 2789 3253 7876 KARUAH 7952.96 635 1093 1407 1995 2343 2789 3252 7875 KARUAH 8184.14 635 1093 1407 1994 2343 2789 3252 7874
KARUAH 8415.33 635 1092 1407 1994 2342 2788 3251 7873 KARUAH 8646.51 634 1092 1407 1993 2342 2787 3251 7871
KARUAH 8877.70 634 1092 1407 1993 2341 2787 3251 7869 KARUAH 9108.89 634 1092 1407 1992 2340 2786 3250 7868 KARUAH 9340.07 634 1091 1406 1992 2340 2785 3250 7866
KARUAH 9571.26 634 1091 1406 1991 2340 2785 3249 7865 KARUAH 9802.44 634 1090 1406 1990 2339 2785 3248 7865
APPENDIX E Great Lakes Council Page E4 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 10033.63 634 1090 1406 1989 2338 2784 3247 7864
K5 10,149.2 KARUAH 10238.47 634 1090 1405 1989 2338 2783 3246 7863 KARUAH 10416.98 634 1090 1405 1988 2338 2783 3246 7862
K6 10,506.2 KARUAH 10618.13 633 1089 1405 1988 2337 2782 3246 7862 KARUAH 10841.94 633 1089 1405 1987 2337 2782 3246 7860
KARUAH 11065.75 633 1089 1405 1987 2337 2781 3245 7859 KARUAH 11289.55 633 1089 1405 1986 2336 2781 3244 7858
KARUAH 11513.36 633 1089 1405 1986 2336 2781 3243 7857 KARUAH 11737.17 633 1089 1405 1985 2335 2780 3243 7856 KARUAH 11960.98 633 1088 1404 1984 2335 2779 3243 7856
K7 12,072.9 KARUAH 12196.41 633 1088 1404 1984 2335 2779 3243 7857
APPENDIX E Great Lakes Council Page E5 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
Low level Bridge, Stroud 12,413.7
KARUAH 12443.47 633 1088 1404 1983 2335 2780 3243 7857 HDWB_Level #2 12,478.4 KARUAH 12690.54 633 1088 1404 1982 2335 2780 3243 7858
KARUAH 12937.60 633 1088 1405 1982 2335 2781 3243 7858 K8 13,061.1 KARUAH 13178.86 633 1088 1405 1982 2336 2781 3244 7859
KARUAH 13414.33 633 1089 1406 1982 2337 2782 3245 7859 KARUAH 13649.79 634 1090 1407 1983 2338 2783 3247 7860
KARUAH 13885.26 634 1091 1408 1983 2339 2785 3248 7860 Confluence, Mill Creek 13,973.3 K9 14,003.0
KARUAH 14121.27 729 1242 1611 2438 2700 3223 3759 9200 KARUAH 14357.82 729 1242 1611 2436 2699 3223 3759 9200
APPENDIX E Great Lakes Council Page E6 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 14594.37 729 1242 1611 2434 2699 3222 3758 9199
K10 14,712.7 KARUAH 14820.97 729 1242 1611 2433 2698 3222 3757 9197 KARUAH 15037.61 729 1242 1611 2432 2697 3221 3755 9196
KARUAH 15254.25 729 1242 1611 2431 2696 3219 3754 9195 KARUAH 15470.88 729 1242 1611 2430 2695 3218 3753 9193 KARUAH 15687.52 729 1242 1610 2429 2694 3216 3751 9192
KARUAH 15904.16 729 1242 1610 2428 2693 3214 3749 9190 KARUAH 16120.80 729 1242 1610 2426 2692 3212 3747 9190
K11 16,229.1 KARUAH 16344.81 729 1242 1610 2426 2691 3212 3746 9190 KARUAH 16576.18 729 1242 1610 2425 2691 3211 3746 9189
KARUAH 16807.56 729 1242 1610 2425 2691 3211 3745 9189 KARUAH 17038.93 729 1242 1610 2425 2691 3210 3745 9189
APPENDIX E Great Lakes Council Page E7 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 17270.31 729 1242 1610 2424 2691 3211 3745 9189
HDWB_Level #3 17,401.5 KARUAH 17501.69 729 1242 1610 2425 2691 3211 3746 9189 KARUAH 17733.06 729 1242 1611 2425 2691 3211 3746 9189
KARUAH 17964.44 729 1242 1611 2426 2691 3212 3746 9190 KARUAH 18195.81 729 1242 1611 2426 2692 3212 3747 9191 KARUAH 18427.19 730 1243 1611 2427 2692 3213 3747 9192
Confluence, Alderley Creek 18,512.6 KARUAH 18658.56 762 1295 1684 2612 2822 3373 3936 9804
K12 18,774.3 KARUAH 18894.13 762 1295 1684 2612 2822 3373 3936 9803 KARUAH 19133.90 762 1295 1684 2612 2822 3372 3936 9803
KARUAH 19373.66 762 1294 1684 2612 2822 3372 3936 9803 KARUAH 19613.43 762 1294 1684 2612 2821 3372 3936 9803
APPENDIX E Great Lakes Council Page E8 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
K13 19,733.3
KARUAH 19841.41 762 1294 1683 2612 2821 3372 3936 9802 KARUAH 20057.60 762 1294 1683 2611 2821 3372 3935 9802 KARUAH 20273.79 761 1294 1683 2611 2821 3371 3935 9801
KARUAH 20489.98 761 1294 1683 2610 2821 3371 3934 9801 KARUAH 20706.18 761 1294 1683 2609 2821 3370 3934 9800 KARUAH 20922.37 761 1293 1682 2608 2820 3370 3933 9798
KARUAH 21138.56 761 1293 1682 2608 2820 3370 3933 9797 K14 21,246.7
KARUAH 21350.72 761 1293 1682 2608 2820 3369 3932 9795 KARUAH 21558.83 761 1293 1682 2607 2819 3369 3932 9793 KARUAH 21766.94 761 1293 1682 2606 2819 3368 3930 9791
KARUAH 21902.00 Bucketts Way bridge, Booral 21,901.9 0 0 0 0 0 0 58 1813 HDWB_Level #4 21,948.0
APPENDIX E Great Lakes Council Page E9 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 22023.23 761 1293 1682 2599 2813 3367 3928 9789
KARUAH 22247.69 761 1292 1682 2597 2812 3365 3926 9787 K16 22,359.9 KARUAH 22467.17 761 1292 1681 2595 2811 3364 3925 9785
KARUAH 22681.66 761 1292 1681 2593 2810 3362 3923 9784 KARUAH 22896.16 761 1292 1680 2591 2809 3361 3922 9783 KARUAH 23110.65 761 1292 1680 2590 2808 3360 3921 9783
Confluence, Booral Creek 23,169.9 K17 23,217.9
KARUAH 23342.89 761 1292 1680 2588 2808 3360 3921 9783 KARUAH 23592.88 761 1292 1680 2587 2807 3359 3920 9783 KARUAH 23842.86 761 1292 1679 2586 2807 3359 3920 9783
KARUAH 24092.85 761 1292 1679 2586 2807 3358 3919 9783 KARUAH 24342.83 761 1291 1679 2585 2806 3358 3919 9783
APPENDIX E Great Lakes Council Page E10 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 24592.82 761 1291 1678 2584 2806 3358 3918 9783
K18 24,717.8 KARUAH 24811.13 761 1291 1678 2584 2806 3357 3918 9783 KARUAH 24997.77 761 1291 1678 2583 2806 3357 3918 9783
KARUAH 25184.40 761 1291 1678 2583 2806 3357 3918 9783 K19 25,277.7 KARUAH 25388.05 761 1291 1678 2583 2806 3357 3918 9783
HDWB_Level #5 25,511.9 KARUAH 25608.72 761 1291 1678 2583 2806 3357 3918 9783
KARUAH 25829.39 761 1291 1678 2583 2805 3357 3918 9783 KARUAH 26050.06 761 1291 1678 2583 2805 3357 3918 9783 KARUAH 26270.73 761 1291 1678 2582 2805 3357 3918 9783
KARUAH 26491.40 761 1291 1678 2582 2806 3357 3918 9783 KARUAH 26712.07 761 1291 1678 2582 2806 3357 3918 9783
APPENDIX E Great Lakes Council Page E11 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
K20 26,822.4
KARUAH 26926.24 761 1292 1678 2582 2806 3357 3918 9783 KARUAH 27133.91 761 1292 1678 2582 2806 3357 3918 9784 KARUAH 27341.59 762 1292 1678 2582 2806 3357 3919 9784
KARUAH 27549.26 762 1292 1678 2582 2806 3357 3919 9785 KARUAH 27756.93 762 1292 1678 2582 2806 3358 3919 9786 K21 27,860.8
KARUAH 27978.07 763 1292 1678 2582 2806 3358 3919 9787 KARUAH 28212.67 763 1293 1678 2582 2807 3358 3919 9788
KARUAH 28447.26 764 1293 1678 2583 2807 3358 3920 9790 KARUAH 28681.86 766 1293 1678 2583 2807 3358 3920 9792 KARUAH 28916.46 768 1294 1678 2583 2808 3359 3921 9794
KARUAH 29151.05 796 1346 1739 2784 2946 3535 4132 10592 KARUAH 29385.65 797 1346 1739 2782 2946 3535 4132 10593
APPENDIX E Great Lakes Council Page E12 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 29620.25 800 1346 1738 2781 2946 3535 4132 10595
KARUAH 29854.85 803 1346 1738 2779 2946 3534 4132 10596 KARUAH 30089.44 806 1346 1738 2778 2946 3534 4131 10598 KARUAH 30324.04 810 1346 1738 2776 2945 3534 4131 10599
KARUAH 30558.64 814 1347 1738 2773 2945 3534 4131 10601 KARUAH 30793.23 819 1348 1738 2771 2946 3534 4132 10603 KARUAH 31027.83 824 1351 1739 2769 2946 3534 4133 10605
ALllworth, Upstream 31,029.5 KARUAH 31268.28 832 1356 1740 2767 2947 3535 4133 10608
K22 31,145.1 KARUAH 31514.59 841 1363 1741 2766 2947 3535 4134 10611 Boat Ramp, Allworth 31,542.4
HDWB_Level #6 31,740.6 KARUAH 31760.90 849 1369 1743 2764 2948 3536 4135 10614
APPENDIX E Great Lakes Council Page E13 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 32007.21 858 1375 1746 2764 2950 3536 4136 10618
KARUAH 32253.52 867 1382 1751 2763 2951 3538 4137 10621 KARUAH 32499.82 877 1389 1757 2763 2953 3539 4139 10624 KARUAH 32746.13 886 1396 1763 2763 2955 3540 4141 10628
KARUAH 32992.44 896 1403 1770 2763 2957 3542 4142 10632 KARUAH 33238.75 906 1410 1776 2764 2959 3544 4144 10636 K23 33,361.9
KARUAH 33480.48 916 1417 1783 2765 2961 3546 4146 10641 KARUAH 33717.63 927 1425 1790 2767 2964 3549 4149 10645
KARUAH 33954.78 937 1432 1797 2770 2967 3551 4152 10650 KARUAH 34191.93 948 1440 1805 2775 2970 3554 4154 10655 KARUAH 34429.09 959 1448 1812 2780 2974 3558 4157 10660
KARUAH 34666.24 970 1456 1820 2786 2978 3561 4161 10664 KARUAH 34903.39 981 1465 1828 2791 2982 3564 4165 10669
APPENDIX E Great Lakes Council Page E14 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 35140.54 993 1473 1835 2798 2986 3568 4168 10674
KARUAH 35377.70 1005 1483 1844 2804 2991 3572 4172 10679 K24 35,496.3 KARUAH 35615.32 1016 1492 1852 2811 2995 3576 4176 10684
KARUAH 35853.43 1028 1502 1861 2818 3001 3581 4181 10689 KARUAH 36091.54 1038 1511 1870 2825 3010 3585 4186 10695 KARUAH 36329.64 1048 1520 1878 2832 3019 3590 4191 10701
Confluence, The Branch 36,548.2 KARUAH 36567.75 1202 1746 2155 3177 3598 4334 5087 13454
KARUAH 36805.86 1212 1756 2164 3184 3596 4332 5084 13455 KARUAH 37043.96 1222 1766 2173 3190 3595 4329 5082 13456 KARUAH 37282.07 1233 1776 2182 3196 3594 4327 5080 13457
KARUAH 37520.17 1244 1785 2191 3203 3593 4325 5078 13458 KARUAH 37758.28 1255 1794 2200 3209 3593 4323 5076 13459
APPENDIX E Great Lakes Council Page E15 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 37996.38 1265 1803 2209 3216 3592 4322 5074 13460
KARUAH 38234.49 1275 1813 2218 3223 3592 4321 5072 13461 KARUAH 38472.60 1283 1821 2226 3230 3593 4320 5070 13462 K25 38,591.7
KARUAH 38712.57 1291 1830 2235 3237 3595 4319 5069 13463 KARUAH 38954.40 1299 1839 2243 3245 3596 4319 5067 13464 KARUAH 39196.23 1307 1847 2251 3252 3597 4318 5066 13465
KARUAH 39438.07 1315 1855 2259 3259 3599 4318 5066 13466 KARUAH 39679.90 1324 1863 2267 3266 3600 4318 5065 13467
KARUAH 39921.73 1333 1871 2275 3273 3601 4318 5064 13468 KARUAH 40163.57 1341 1879 2284 3281 3603 4318 5064 13469 KARUAH 40405.40 1353 1889 2294 3288 3604 4319 5064 13471
KARUAH 40647.23 1365 1900 2304 3296 3612 4320 5064 13472 KARUAH 40889.07 1377 1911 2314 3304 3621 4322 5064 13474
APPENDIX E Great Lakes Council Page E16 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 41130.90 1390 1922 2324 3311 3630 4323 5064 13477
Confluence Limeburners 41,237.3 Creek KARUAH 41372.73 1435 1983 2396 3396 3764 4520 5315 14359 KARUAH 41614.56 1448 1994 2407 3405 3765 4519 5311 14359
KARUAH 41856.40 1461 2006 2418 3413 3766 4519 5308 14360 KARUAH 42098.23 1475 2019 2430 3422 3776 4518 5306 14361 KARUAH 42340.06
K26 42,461.0 1488 2031 2441 3431 3786 4517 5304 14362 KARUAH 42583.68 1500 2042 2452 3441 3797 4517 5302 14364
KARUAH 42829.07 1512 2054 2463 3451 3808 4517 5301 14365 KARUAH 43074.46 1523 2065 2474 3462 3820 4518 5300 14367 KARUAH 43319.85 1536 2076 2485 3473 3832 4520 5299 14368
Karuah by_pass 43,363.8
APPENDIX E Great Lakes Council Page E17 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 43565.24 1548 2089 2497 3485 3846 4521 5298 14370
KARUAH 43810.63 1561 2102 2513 3498 3860 4523 5297 14372 KARUAH 44056.02 1575 2120 2530 3512 3876 4525 5295 14375 KARUAH 44301.41 1595 2139 2548 3527 3893 4529 5294 14377
KARUAH 44546.80 1615 2158 2567 3543 3911 4547 5296 14380 KARUAH 44792.19 1638 2180 2588 3562 3932 4566 5298 14384 KARUAH 45037.58 1662 2203 2611 3583 3955 4587 5301 14388
KARUAH 45282.97 1687 2228 2636 3605 3979 4612 5305 14394 K27 45,405.7
KARUAH 45519.70 1714 2254 2661 3631 4011 4648 5317 14402 KARUAH 45747.75 1738 2279 2687 3657 4042 4681 5350 14409 KARUAH 45975.81 1763 2305 2712 3682 4071 4712 5381 14417
KARUAH 46203.87 1786 2328 2735 3704 4096 4739 5408 14424 KARUAH 46431.93 1806 2347 2755 3724 4117 4763 5431 14431
APPENDIX E Great Lakes Council Page E18 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP
KARUAH 46659.98 1822 2363 2771 3740 4133 4782 5450 14437
KARUAH 46888.04 1834 2375 2783 3752 4145 4796 5464 14443 K28 47,002.1 Karuah Bridge, Pacific 47,012.7 Highway
KARUAH 47015.71 1838 2379 2787 3756 4149 4801 5469 14444 End of model 47,029.4
FLOODPLAIN OPENINGS BOORAL_2 20.00 0 0 2 62 85 165 234 837
BOORAL_1 10.00 0 0 1 51 71 138 218 1026
BOORAL_BR 60.00 761 1293 1679 2493 2663 3066 3428 6307
APPENDIX E Great Lakes Council Page E19 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Design Peak Flood Flows (cu m/sec) Model Calculation Points Location River (36 hour storm, flood peak co-incident with peak tide) Section River 50% 20% 10% 5% 2% 1% 0.5% PMP Distance AEP AEP AEP AEP AEP AEP AEP WASHPOOL_BR 60.00 631 1080 1389 1970 2314 2755 3217 7676
STROUD_RAIL 60.00 295 539 929 1142 1069 1274 1485 2980
WPOOL_UPASS 247.33 5 14 19 27 32 37 39 44
STROUD_RAIL_UBRIDG 2 16 14 25 25 30 25 15 E 190.00
APPENDIX E Great Lakes Council Page E20 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Limited
APPENDIX F
SENSITIVITY TESTING
Great Lakes Council Karuah River Flood Study Final Report - November 2010 R90\07012.V8 . Paterson Consultants Pty Ltd
APPENDIX F
SENSITIVITY TESTING
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 2025.54 Start of model 2025.5 42.72 42.72 42.72 40.21 43.46 43.39 KARUAH 2275.35 42.35 42.35 42.35 39.98 43.09 43.01 KARUAH 2525.17 K1 2525.2 41.91 41.91 41.91 39.72 42.62 42.55 KARUAH 2756.00 41.68 41.68 41.68 39.55 42.36 42.25 KARUAH 2986.83 41.50 41.50 41.50 39.40 42.15 42.02 KARUAH 3217.66 41.34 41.34 41.34 39.27 41.98 41.83 KARUAH 3448.49 41.20 41.20 41.20 39.16 41.84 41.66 Low level bridge, Stroud Road 3353.0 KARUAH 3634.00 41.10 41.10 41.10 39.75 41.74 41.54 Bridge, North Coast Rail, Stroud 3655.0 Road
APPENDIX F Great Lakes Council Page F1 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 3717.60 40.73 40.73 40.73 39.83 41.29 41.23 KARUAH 3731.72 K2 3731.7 40.72 40.72 40.72 39.42 41.28 41.22 KARUAH 3808.88 40.67 40.67 40.67 38.86 41.22 41.16 KARUAH 4022.69 40.54 40.54 40.54 38.77 41.08 41.01 KARUAH 4236.50 40.42 40.42 40.42 38.69 40.97 40.89 KARUAH 4450.31 40.32 40.32 40.32 38.61 40.87 40.78 KARUAH 4664.12 40.12 40.12 40.12 38.42 40.67 40.60 Confluence, Mammy Johnsons Creek 4702.4 KARUAH 4877.93 K4 4877.9 39.64 39.64 39.64 37.90 40.22 40.17 KARUAH 5076.30 39.37 39.37 39.37 37.55 39.97 39.90 KARUAH 5274.67 39.15 39.15 39.15 37.26 39.77 39.68 KARUAH 5473.04 38.98 38.98 38.98 37.02 39.60 39.50 KARUAH 5473.04 38.98 38.98 38.98 37.02 39.60 39.50 KARUAH 5632.06 38.84 38.84 38.84 36.87 39.46 39.36
APPENDIX F Great Lakes Council Page F2 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 5791.09 K4 5791.1 38.62 38.62 38.62 36.67 39.23 39.14 Confluence, Ramstation Creek 5885.1 KARUAH 5916.20 38.37 38.37 38.37 36.44 38.98 38.90 HDWB_Level #1 5918.1 KARUAH 5927.28 38.35 38.35 38.35 36.44 38.96 38.88 High Level RTA bridge, "Washpool" 5956.1 KARUAH 5986.20 38.17 38.17 38.17 36.34 38.73 38.72 KARUAH 5996.20 38.14 38.14 38.14 36.30 38.69 38.70 KARUAH 6223.95 37.69 37.69 37.69 35.92 38.24 38.24 KARUAH 6223.95 37.69 37.69 37.69 35.92 38.24 38.24 KARUAH 6454.32 37.24 37.24 37.24 35.54 37.78 37.78 KARUAH 6684.69 36.80 36.80 36.80 35.15 37.34 37.34 KARUAH 6915.06 36.37 36.37 36.37 34.76 36.90 36.90 KARUAH 7145.44 35.93 35.93 35.93 34.36 36.46 36.45
APPENDIX F Great Lakes Council Page F3 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 7375.81 35.48 35.48 35.48 33.94 36.00 36.00 KARUAH 7606.18 K4.5 7606.2 35.00 35.00 35.00 33.47 35.53 35.52 KARUAH 7837.37 34.50 34.50 34.50 32.95 35.03 35.03 KARUAH 8068.55 34.02 34.02 34.02 32.44 34.55 34.54 KARUAH 8299.74 33.54 33.54 33.54 31.93 34.08 34.07 KARUAH 8530.92 33.08 33.08 33.08 31.41 33.63 33.62 KARUAH 8762.11 32.65 32.65 32.65 30.90 33.20 33.19 KARUAH 8993.29 32.24 32.24 32.24 30.42 32.80 32.80 KARUAH 9224.48 31.88 31.88 31.88 29.98 32.44 32.43 KARUAH 9455.66 31.55 31.55 31.55 29.61 32.12 32.10 KARUAH 9686.85 31.27 31.27 31.27 29.30 31.83 31.82 KARUAH 9918.03 31.03 31.03 31.03 29.05 31.59 31.57 KARUAH 10149.22 K5 10149.2 30.84 30.84 30.84 28.86 31.40 31.36 KARUAH 10327.72 30.64 30.64 30.64 28.65 31.20 31.17
APPENDIX F Great Lakes Council Page F4 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 10506.23 K6 10506.2 30.28 30.28 30.28 28.32 30.85 30.85 KARUAH 10730.04 29.85 29.85 29.85 27.94 30.44 30.43 KARUAH 10953.84 29.47 29.47 29.47 27.56 30.07 30.06 KARUAH 11177.65 29.12 29.12 29.12 27.18 29.74 29.72 KARUAH 11401.46 28.80 28.80 28.80 26.81 29.43 29.41 KARUAH 11625.27 28.51 28.51 28.51 26.45 29.16 29.13 KARUAH 11849.07 28.24 28.24 28.24 26.11 28.91 28.87 KARUAH 12072.88 K7 12072.9 28.00 28.00 28.00 25.79 28.68 28.64 KARUAH 12319.94 27.69 27.69 27.69 25.40 28.40 28.35 Low level Bridge, Stroud 12413.7 HDWB_Level #2 12478.4 KARUAH 12567.00 27.35 27.35 27.35 24.97 28.07 28.02 KARUAH 12814.07 26.98 26.98 26.98 24.52 27.71 27.66 KARUAH 13061.13 K8 13061.1 26.58 26.58 26.58 24.07 27.30 27.25
APPENDIX F Great Lakes Council Page F5 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 13296.59 26.26 26.26 26.26 23.72 26.99 26.92 KARUAH 13532.06 26.01 26.01 26.01 23.41 26.75 26.66 KARUAH 13767.53 25.82 25.82 25.82 23.16 26.55 26.45 Confluence, Mill Creek 13973.3 KARUAH 14002.99 K9 14003.0 25.65 25.65 25.65 22.94 26.39 26.29 KARUAH 14239.54 25.34 25.34 25.34 22.54 26.07 25.99 KARUAH 14476.10 24.92 24.92 24.92 21.88 25.65 25.58 KARUAH 14712.65 K10 14712.7 24.23 24.23 24.23 20.98 25.01 24.97 KARUAH 14929.29 23.77 23.77 23.77 20.31 24.61 24.54 KARUAH 15145.93 23.35 23.35 23.35 19.76 24.32 24.22 KARUAH 15362.57 23.01 23.01 23.01 19.33 24.07 23.95 KARUAH 15579.20 22.74 22.74 22.74 18.99 23.86 23.72 KARUAH 15795.84 22.53 22.53 22.53 18.71 23.69 23.53 KARUAH 16012.48 22.36 22.36 22.36 18.49 23.55 23.37
APPENDIX F Great Lakes Council Page F6 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 16229.12 K11 16229.1 22.24 22.24 22.24 18.31 23.43 23.24 KARUAH 16460.50 22.00 22.00 22.00 18.11 23.20 23.02 KARUAH 16691.87 21.76 21.76 21.76 17.90 22.95 22.78 KARUAH 16923.25 21.50 21.50 21.50 17.68 22.68 22.52 KARUAH 17154.62 21.22 21.22 21.22 17.45 22.39 22.23 KARUAH 17386.00 20.91 20.91 20.91 17.20 22.06 21.91 HDWB_Level #3 17401.5 KARUAH 17617.37 20.56 20.56 20.56 16.93 21.71 21.56 KARUAH 17848.75 20.18 20.18 20.18 16.63 21.30 21.16 KARUAH 18080.12 19.75 19.75 19.75 16.30 20.83 20.70 KARUAH 18311.50 19.26 19.26 19.26 15.92 20.30 20.19 Confluence, Alderley Creek 18512.6 KARUAH 18542.88 18.62 18.62 18.62 15.43 19.60 19.53 KARUAH 18774.25 K12 18774.3 17.71 17.71 17.71 14.76 18.60 18.62
APPENDIX F Great Lakes Council Page F7 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 19014.02 16.99 16.99 16.99 14.25 17.86 17.87 KARUAH 19253.78 16.54 16.54 16.54 13.90 17.36 17.33 KARUAH 19493.54 16.18 16.18 16.18 13.65 16.97 16.92 KARUAH 19733.31 K13 19733.3 15.77 15.77 15.77 13.38 16.51 16.47 KARUAH 19949.50 15.52 15.52 15.52 13.22 16.23 16.17 KARUAH 20165.70 15.30 15.30 15.30 13.06 15.98 15.90 KARUAH 20381.89 15.08 15.08 15.08 12.91 15.74 15.64 KARUAH 20598.08 14.85 14.85 14.85 12.76 15.49 15.39 KARUAH 20814.27 14.58 14.58 14.58 12.54 15.21 15.10 KARUAH 21030.47 14.25 14.25 14.25 12.19 14.86 14.76 KARUAH 21246.66 K14 21246.7 13.71 13.71 13.72 11.44 14.35 14.25 KARUAH 21454.77 13.06 13.06 13.06 10.47 13.76 13.65 KARUAH 21662.89 12.40 12.40 12.41 9.88 13.18 13.05 KARUAH 21871.00 11.77 11.77 11.77 9.48 12.65 12.51
APPENDIX F Great Lakes Council Page F8 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 Bucketts Way bridge, Booral 21901.9 KARUAH 21911.00 11.39 11.39 11.39 9.15 12.32 12.30 HDWB_Level #4 21948.0 KARUAH 22135.46 11.47 11.47 11.48 8.80 12.39 12.27 KARUAH 22359.92 K16 22359.9 11.20 11.20 11.21 8.45 12.14 12.01 KARUAH 22574.41 10.95 10.95 10.96 8.02 11.94 11.80 KARUAH 22788.91 10.78 10.78 10.79 7.73 11.75 11.62 KARUAH 23003.40 10.60 10.60 10.61 7.55 11.57 11.44 Confluence, Booral Creek 23169.9 KARUAH 23217.90 K17 23217.9 10.43 10.43 10.44 7.42 11.40 11.27 KARUAH 23467.88 10.25 10.25 10.27 7.26 11.22 11.09 KARUAH 23717.87 10.08 10.08 10.09 7.08 11.04 10.91 KARUAH 23967.86 9.90 9.90 9.92 6.90 10.87 10.73 KARUAH 24217.84 9.73 9.72 9.74 6.70 10.69 10.55
APPENDIX F Great Lakes Council Page F9 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 24467.82 9.55 9.55 9.57 6.50 10.52 10.37 KARUAH 24717.81 K18 24717.8 9.37 9.37 9.39 6.29 10.34 10.19 KARUAH 24904.45 9.14 9.14 9.16 6.06 10.10 9.98 KARUAH 25091.08 8.87 8.86 8.89 5.87 9.81 9.72 KARUAH 25277.72 K19 25277.7 8.60 8.59 8.62 5.74 9.50 9.45 KARUAH 25498.39 8.38 8.37 8.41 5.60 9.28 9.22 HDWB_Level #5 25511.9 KARUAH 25719.06 8.17 8.16 8.20 5.44 9.07 9.00 KARUAH 25939.73 7.97 7.96 8.01 5.28 8.86 8.79 KARUAH 26160.39 7.78 7.76 7.81 5.11 8.65 8.58 KARUAH 26381.06 7.58 7.57 7.62 4.94 8.45 8.37 KARUAH 26601.73 7.39 7.37 7.43 4.78 8.25 8.16 KARUAH 26822.40 K20 26822.4 7.20 7.18 7.25 4.62 8.05 7.95 KARUAH 27030.07 7.02 7.00 7.07 4.47 7.85 7.75
APPENDIX F Great Lakes Council Page F10 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 27237.75 6.83 6.81 6.89 4.30 7.66 7.56 KARUAH 27445.42 6.60 6.57 6.66 4.15 7.42 7.33 KARUAH 27653.10 6.34 6.32 6.41 4.00 7.15 7.07 KARUAH 27860.77 K21 27860.8 6.12 6.09 6.19 3.86 6.88 6.82 KARUAH 28095.37 5.91 5.88 5.99 3.73 6.64 6.58 KARUAH 28329.96 5.71 5.68 5.80 3.61 6.44 6.36 KARUAH 28564.56 5.53 5.50 5.62 3.50 6.26 6.16 KARUAH 28799.16 5.37 5.34 5.47 3.41 6.09 5.99 KARUAH 29033.76 5.21 5.17 5.32 3.32 5.91 5.81 KARUAH 29268.35 5.04 5.00 5.17 3.23 5.72 5.62 KARUAH 29502.95 4.93 4.88 5.05 3.16 5.58 5.48 KARUAH 29737.55 4.82 4.77 4.95 3.10 5.46 5.35 KARUAH 29972.14 4.73 4.68 4.87 3.05 5.37 5.25 KARUAH 30206.74 4.67 4.61 4.82 3.02 5.32 5.18
APPENDIX F Great Lakes Council Page F11 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 30441.34 4.63 4.57 4.78 2.99 5.27 5.11 KARUAH 30675.94 4.60 4.54 4.76 2.96 5.26 5.09 KARUAH 30910.53 4.59 4.53 4.75 2.95 5.25 5.07 ALllworth, Upstream 31029.5 KARUAH 31145.13 K22 31145.1 4.59 4.53 4.74 2.94 5.24 5.05 KARUAH 31391.44 4.56 4.50 4.72 2.93 5.22 5.03 Boat Ramp, Allworth 31542.4 KARUAH 31637.75 4.54 4.48 4.70 2.91 5.19 5.00 HDWB_Level #6 31740.6 KARUAH 31884.05 4.52 4.45 4.68 2.90 5.17 4.98 KARUAH 32130.36 4.49 4.43 4.65 2.88 5.14 4.95 KARUAH 32376.67 4.46 4.40 4.63 2.86 5.11 4.92 KARUAH 32622.98 4.43 4.37 4.60 2.85 5.08 4.89 KARUAH 32869.29 4.40 4.34 4.57 2.83 5.05 4.86
APPENDIX F Great Lakes Council Page F12 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 33115.59 4.37 4.30 4.54 2.81 5.01 4.82 KARUAH 33361.90 K23 33361.9 4.33 4.27 4.51 2.79 4.97 4.78 KARUAH 33599.05 4.30 4.23 4.48 2.77 4.94 4.74 KARUAH 33836.20 4.27 4.20 4.45 2.74 4.90 4.71 KARUAH 34073.36 4.23 4.16 4.42 2.72 4.87 4.67 KARUAH 34310.51 4.20 4.13 4.39 2.70 4.83 4.63 KARUAH 34547.66 4.16 4.10 4.36 2.68 4.80 4.60 KARUAH 34784.81 4.13 4.06 4.33 2.66 4.76 4.56 KARUAH 35021.96 4.10 4.03 4.30 2.64 4.73 4.52 KARUAH 35259.12 4.06 3.99 4.27 2.62 4.69 4.48 KARUAH 35496.27 K24 35496.3 4.03 3.96 4.23 2.60 4.65 4.44 KARUAH 35734.38 3.99 3.92 4.20 2.58 4.61 4.40 KARUAH 35972.48 3.95 3.88 4.16 2.56 4.57 4.36 KARUAH 36210.59 3.90 3.84 4.13 2.53 4.52 4.31
APPENDIX F Great Lakes Council Page F13 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 36448.70 3.82 3.75 4.05 2.49 4.43 4.24 Confluence, The Branch 36548.2 KARUAH 36686.80 3.70 3.60 3.95 2.44 4.30 4.13 KARUAH 36924.91 3.63 3.52 3.88 2.41 4.22 4.05 KARUAH 37163.01 3.56 3.45 3.82 2.38 4.13 3.97 KARUAH 37401.12 3.49 3.37 3.76 2.35 4.05 3.89 KARUAH 37639.23 3.42 3.29 3.70 2.32 3.98 3.82 KARUAH 37877.33 3.35 3.22 3.64 2.29 3.90 3.74 KARUAH 38115.44 3.28 3.14 3.59 2.26 3.82 3.67 KARUAH 38353.54 3.21 3.06 3.53 2.23 3.74 3.59 KARUAH 38591.65 K25 38591.7 3.14 2.99 3.47 2.21 3.66 3.51 KARUAH 38833.48 3.11 2.95 3.45 2.19 3.63 3.47 KARUAH 39075.32 3.06 2.89 3.41 2.17 3.58 3.42 KARUAH 39317.15 3.01 2.83 3.37 2.15 3.52 3.36
APPENDIX F Great Lakes Council Page F14 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 39558.98 2.96 2.78 3.33 2.13 3.46 3.30 KARUAH 39800.82 2.90 2.72 3.28 2.11 3.40 3.24 KARUAH 40042.65 2.85 2.65 3.24 2.09 3.34 3.18 KARUAH 40284.48 2.79 2.59 3.20 2.07 3.28 3.12 KARUAH 40526.32 2.74 2.53 3.15 2.05 3.21 3.06 KARUAH 40768.15 2.68 2.47 3.11 2.03 3.15 3.00 KARUAH 41009.98 2.62 2.40 3.07 2.02 3.08 2.93 KARUAH 41251.81 2.55 2.32 3.01 1.99 3.00 2.86 Confluence Limeburners Creek 41237.3 KARUAH 41493.65 2.47 2.21 2.95 1.97 2.91 2.77 KARUAH 41735.48 2.41 2.14 2.90 1.95 2.83 2.70 KARUAH 41977.31 2.35 2.06 2.85 1.94 2.75 2.62 KARUAH 42219.15 2.28 1.98 2.81 1.92 2.67 2.55 KARUAH 42460.98 K26 42461.0 2.22 1.91 2.76 1.90 2.59 2.47
APPENDIX F Great Lakes Council Page F15 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 42706.37 2.15 1.83 2.71 1.89 2.51 2.39 KARUAH 42951.76 2.09 1.75 2.66 1.87 2.43 2.31 KARUAH 43197.15 2.02 1.67 2.62 1.85 2.35 2.23 Karuah by_pass 43363.8 KARUAH 43442.54 1.95 1.59 2.57 1.84 2.27 2.15 KARUAH 43687.93 1.89 1.51 2.53 1.82 2.18 2.07 KARUAH 43933.32 1.82 1.45 2.48 1.81 2.10 1.99 KARUAH 44178.71 1.75 1.41 2.44 1.79 2.01 1.91 KARUAH 44424.11 1.68 1.37 2.39 1.78 1.93 1.82 KARUAH 44669.50 1.62 1.33 2.35 1.76 1.84 1.74 KARUAH 44914.89 1.55 1.30 2.32 1.75 1.76 1.66 KARUAH 45160.28 1.49 1.27 2.28 1.74 1.68 1.58 KARUAH 45405.67 K27 45405.7 1.44 1.24 2.26 1.73 1.62 1.51 KARUAH 45633.73 1.39 1.21 2.22 1.72 1.54 1.44
APPENDIX F Great Lakes Council Page F16 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Flood Level for Various Run Conditions River (See Run Conditions at end of this Table) Model Identification Location River Section Distance (m AHD) (m) Run1 Run2 Run3 Run4 Run5 Run6 KARUAH 45861.79 1.34 1.19 2.19 1.71 1.48 1.39 KARUAH 46089.84 1.30 1.17 2.16 1.71 1.42 1.33 KARUAH 46317.90 1.26 1.15 2.13 1.70 1.35 1.28 KARUAH 46545.96 1.21 1.13 2.08 1.69 1.28 1.22 KARUAH 46774.01 1.14 1.10 2.03 1.68 1.19 1.15 KARUAH 47002.07 K28 47002.1 1.06 1.06 1.96 1.66 1.07 1.07 Karuah Bridge, Pacific Highway 47012.7 KARUAH 47029.36 End of model 47029.4 1.06 1.06 1.96 1.66 1.06 1.06
K25 38591.7 Confluence Limeburners Creek 41237.3 K26 42461.0
Run Conditions:
APPENDIX F Great Lakes Council Page F17 Karuah River Flood Study Final Report - November 2010 R90\07012.V8 Paterson Consultants Pty Ltd
Run 1: The 1% AEP 36 hour design event with peak river flood flows concurrent with a maximum tidal level of 0.9 metres at Port Stephens. Run 2: The 1% AEP 36 hour design event with the peak river flood coincident with the minimum tidal cycle level. Run 3: The design 1% AEP 36 hour design event, concurrent with the 0.9 metre tidal level together with a 0.8 metre allowance for a climate change induced ocean level rise (the maximum predicted by IPCC for the projection period to 2090/2099). Run 4: The 10% AEP flood event with a 1% AEP ocean level. Run 5: The 1% AEP flood with the inflows factored by 1.2, to represent a 20% increase in flows. Run 6: The 1% AEP flood using the MIKE-11 model with the friction in the model increased by 20 percent.
APPENDIX F Great Lakes Council Page F18 Karuah River Flood Study Final Report - November 2010 R90\07012.V8