karuah river flood study final report - mid-coast council

GREAT LAKES COUNCIL

KARUAH RIVER FLOOD STUDY

FINAL REPORT

November 2010

Version 8Authorised for Release Copy of .

GREAT LAKES COUNCIL


FINAL REPORT

November 2010

Prepared By:

PATERSON CONSULTANTS PTY LIMITED1/45 PRINCE STREETGRAFTON NSW 2460

P O BOX 596GRAFTON NSW 2460

Tel: (02) 6643 1588Fax: (02) 6642 7566

E-mail: [email protected]

.

DOCUMENT CONTROL SHEET

Paterson Consultants Pty LtdSuite 1, 45 Prince StreetGrafton NSW 2460

P O Box 596Grafton 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 NumberDestination

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 .

Great Lakes CouncilKaruah River Flood Study

Final Report - November 2010R90 \07012.V8

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 173.2 Previous Studies, Documents 173.3 Government Agency Records 283.4 Resident Interviews 32

4. HYDROLOGICAL INVESTIGATION 34

4.1 Overview 344.2 Hydrology Model - Karuah River 344.3 Design Flood Hydrographs 384.4 Estimation of PMF 394.5 Flood Frequency Analysis 414.6 Comparison of Results 44

5. HYDRODYNAMIC INVESTIGATION 45

5.1 Overview 455.2 MIKE-11 Model of the Karuah River 455.3 MIKE-11 Model Calibration and Verification 49

6. DESIGN FLOOD LEVELS 55

6.1 Process of Assessment 556.2 Design Tailwater Levels 556.3 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

Paterson Consultants Pty Limited

Great Lakes CouncilKaruah River Flood StudyFinal Report - November 2010R90\07012.V8

4

TABLE OF CONTENTS (Cont) PAGE NUMBER

REFERENCES 65

GLOSSARY 67

TABLES

0. DWE Gauging Station 181. Significant Historical Floods (Station 209003, "Karuah River @ Booral") 192. Historical Flood Data – RTA Bridges 203. Predicted Peak Discharges – Karuah River (Source: PWD – 1981) 214. Recorded Peak Flood Levels (Source: PWD Peak Level Recorders) 225. Estimated Peak Flood Discharges – Karuah River at Booral 256. Design Water Levels at Karuah (Source: Port Stephens Flood Study, Reference 8) 267. Recorded Flood Levels, Hunter District Water Board 288 Ranked Flood Sources 1971 to 2007 – Karuah River at Booral 309. Relevant Rainfall Stations 3210. Results of Additional Survey from Resident Survey 3311. Comparative 4-day Total Rainfalls 3612. Comparison of Modelled and Recorded Peak Discharge 3713. Peak Discharges – Design Floods 3914. PMP Rainfall Estimates (Karuah River at Karuah) 4015. Peak Discharges - PMF (Source: GSAM Method) 4116. Peak Flood Discharges - “Karuah River @ Booral” 4317. Comparison of Peak Flows, Karuah River at Booral 4418. Localities and Cross-sections – River Distance 4619. Hydrograph Input Location 4920. Comparison of Historical Flood Levels 5121. Comparison of Historical Flood Levels and Design Flood Levels 5222. Adopted Mannings `n’ Values 5423. Design Flood Levels at Booral 56

FIGURES

1. Study Locality2. Study Catchment3. Rainfall Stations4. RORB Model Layout5. Comparison - 1977 & 1978 Floods6. Comparison - 1990 Floods7. Comparison - 2001 Flood8. Comparison - 2007 Flood




5

TABLE OF CONTENTS (Cont) PAGE NUMBER

FIGURES (Cont)

9. Flood Frequency - Karuah River at Booral10. Tributary Inflows - 1% AEP Storm, 36 Hour Duration11. Karuah River Flows - 1% AEP Storm, 36 Hour Duration12 Comparison 1% AEP to PMF Flows, Karuah River13. Location of Cross Sections – Upper14. Location of Cross Sections – Lower15. MIKE-11 Model Layout16. Historical Water Levels – Sheet 117. Historical Water Levels – Sheet 218. Comparison of Model Results and Booral Rating Curve19. Historical Flood Profiles, Karuah River – Upper20. Historical Flood Profiles, Karuah River – Lower21. Comparison of Flood Levels, Karuah River at Booral22. Design Tailwater Levels, Karuah23. Design Flood Profiles, Karuah River – Upper24. Design Flood Profiles, Karuah River – Lower25. Design Flood Levels, Karuah River near Karuah26. Sensitivity Testing, Karuah River – Upper27. Sensitivity Testing, Karuah River – Lower28 Diagrammatic Representation, Flood Levels29 Provisional Flood Hazard 5% AEP - Sheet 130 Provisional Flood Hazard 5% AEP - Sheet 231 Provisional Flood Hazard 5% AEP - Sheet 332 Provisional Flood Hazard 1% AEP - Sheet 133 Provisional Flood Hazard 1% AEP - Sheet 234 Provisional Flood Hazard 1% AEP - Sheet 335 Provisional Flood Hazard 0.5% AEP - Sheet 136 Provisional Flood Hazard 0.5% AEP - Sheet 237 Provisional Flood Hazard 0.5% AEP - Sheet 338 Provisional Flood Hazard PMF - Sheet 139 Provisional Flood Hazard PMF - Sheet 240 Provisional Flood Hazard PMF - Sheet 3

APPENDICES

A. Annual Flood Series, Station 209003, "Karuah River @ Booral"B. Daily Rainfall and Pluviometer StationsC. Design Rainfalls - Intensity-Frequency-DurationD. Design Flood LevelsE. Design Flood DischargesF. Sensitivity Testing - Design Flood Levels



6

ACKNOWLEDGEMENTS

This study has been undertaken by Paterson Consultants under the auspices of the Great Lakes FloodplainRisk 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 contributionbasis under the State assisted floodplain management program.




7

FOREWORD

The New South Wales Government's Flood Prone Land Policy is directed at providing solutions to existingflooding problems in developed areas as well as ensuring that new development is compatible with the floodhazard 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. TheState Government provides specialist technical advice and financial subsidies for studies and capital worksto 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 foursequential 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 proposeddevelopment.

* 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 includesuse of local environmental plans to ensure new development is compatible with the floodhazard.

The Karuah River Flood Study constitutes part of the first stage of the management process for the KaruahRiver from Stroud Road to Karuah. The Karuah River Flood Study has been prepared for Great LakesCouncil to determine an appropriate floodplain risk management strategy.



8

SUMMARY

The Karuah River Flood Study has been undertaken to provide flood information for establishment of afloodplain risk management planfor the Karuah River. The end use of this study will most likely be for thesetting 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 residentinterviews;

- definition of waterway areas along the Karuah River by ground survey;

- establishment and calibration of an hydrologic model and a riverine hydraulic model topredict design flood levels for the 0.5, 1, 2, 5, 10 and 20% AEP floods and theProbable 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 floodsinvestigated.

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 andGreat Lakes Council;

- flood data derived from site inspection and resident questionnaires.

The DWE published flood data (through the “PINNEENA” CD) indicates the only relevant hydrographicstation 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 and2001 with peak levels between RL 10.35 m AHD and 8.92 m AHD.




9

The RTA bridge drawings for the Karuah River at the Stroud – Dungog Road (the “Washpool”) and theKaruah River at Booral quote historical flood levels. At Washpool, the levels quoted are RL 38.5 m AHDand RL 37.1 m AHD for 1850 and 1946 floods, while at Booral, the level quoted is RL 11.78 m AHD forthe 1946 flood.

Calculation files from the PWD, Hunter District Office, circa 1981:

- identify hydrological analysis for the Karuah River leading to peak flood dischargeestimates 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 the1976, 1977 and 1978 floods.

Great Lakes Council and Port Stephens Council have been undertaking floodplain management studies forthe foreshores of Port Stephens. The Port Stephens Flood Study (Reference 8) provides analysis of waterlevels in Port Stephens and some hydrological analysis of the Karuah River catchment. The Port Stephensstudy has been used to set prevailing water levels at Karuah for this study, while the hydrological analysis isof limited value due to its concentration on rainfall events of days (for determination of flood water levels inPort 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 levelsrecorded between Washpool and Allworth. These reports produce the only flood levels along the KaruahRiver for a single event, noting that the 1978 flood was the highest of the 1976, 1977 and 1978 series, but itonly 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 Stroudas occurring in 1956. Examination of the recorded flood levels in Stroud suggest that in floods up to thehistorically recorded events, Stroud will be above the Karuah River flood levels and thus, Karuah floodlevels 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 ofthe 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 oftwo operational daily rainfall stations in the catchment, while the nearest pluviometers are located nearWilliamtown and at Chichester Dam.

An initial contact with the residents of the riverine corridor through the study area was initiated byquestionnaire. Three hundred and sixty seven (367) questionnaires were issued to property owners. Sixtyeight (68) responses were received. Fifty five (55) responses indicated “no information on floodingavailable” and within the remaining thirteen (13) responses, no flood data was identified that justified thecost of ground survey to collect the data.



10

A “doorknock” program identified 13 additional marks, representing either 2007 flood peaks or “highestrecorded flood” based on oral history.

The total catchment of the Karuah River at Karuah is 1456 sq kilometres, while the Karuah Rivercatchments 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, toprovide hydrograph inputs to a hydrodynamic model.

The RORB model was initially calibrated and verified against the 1978, 1990 and 2001 floods. Thesefloods (ranked 5th, 2nd and 6th highest at Booral) were selected as having reasonable rainfall data across thecatchment and recorded hydrograph data at Booral). Other floods (1971 and 1985) were not used becauseof missing data.

Initial work on the hydrodynamic model indicated discrepancies in some of the historical flood data, whilework on the RORB model indicated that the Karuah River catchment was very sensitive to inherentassumptions regarding total rainfall, rainfall patterns and losses (the difference between total rainfall andflood 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 versusrecorded 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 36hour 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 andRunoff 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 andKaruah were 3,313 cu m/sec and 4,060 cu m/sec respectively.




11

The Probable Maximum Flood (PMF) was derived using Probable Maximum Precipitation (PMP) and thecalibrated RORB model. The PMP analysis was based on the three separate methods published by theBureau of Meteorology (namely, Generalised Short Duration Method (GSDM), Generalised TropicalStorm 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 and12,710 cu m/sec respectively.

The “critical” duration for the PMP storm lies between the 12 hour and 24 hour duration. Given the resultsof this study are to be used for emergency planning purposes, the 24 hour storm has been adopted forprediction 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 atBooral 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 historically recordedevents is reasonable and consequently, the RORB model has been used to produce design inflowhydrographs for the hydrodynamic model.

An hydrodynamic model of the Karuah River from Stroud Road to Karuah was established using MIKE-11software. 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 theywill 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 andfive recorded flood levels in the 2007 flood;

- flood levels and discharge rating for Station 209003 “Karuah River at Booral” over theperiod 1969 to current;



12

- historical “highest flood levels” recorded on bridge drawings and derived fromresidentinterviews (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 historically recorded flood events.

In testing for the historical flood events (1977, 1978, 1990, 2001 and 2007), tailwater levels in PortStephens were derived from actual measurements (2001 and 2007) or tidal predictions over the relevantdates (1977, 1978 and 1990).

Considerable investigation was made into differences between modelled flood levels and HDWB peak levelindicators. After testing, the conclusion drawn was that there were some booking or transposition errors inthe HDWB data.

The calibration and verification of both the RORB hydrology model and the MIKE-11 hydraulic modelareconsidered adequate for prediction of design flood levels for floodplain management along the KaruahRiver.

As noted earlier, the design flood hydrograph inputs for the various design floods (between 50% AEP and0.5% 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. Thesethree 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 whichrecognises historically recorded storm surges but that there is not a direct relationshipbetween river flooding and ocean surges;

- A climate change induced increase in ocean level of 0.8 metres (as indicated by theIPCC 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 theProbable Maximum Flood (PMF). The design flood results are tabulated in Appendices D and E.




13

Sensitivity testing of the design floods has been undertaken for:

- increases of 20 percent in flood discharges or river friction for comparison against anadopted base case (1% AEP flood);

- various water level scenarios in Port Stephens ranging from a 0.9 m AHD maximumtidal level to an RL 1.5 m AHD 1% ocean level plus allowance for a 0.8 m climatechange 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 forthe Karuah River near Stroud.

Changes to the assumption regarding timing of the river flood compared to the tidal cycle affect flood levelsfrom Karuah to the confluence of The Branch with the Karuah River. Ocean flooding dominates the designflood levels over the last three kilometres of the Karuah River to Karuah. A climate change inducedincrease in ocean water level will increase design flood levels below Allworth. The variation of designflood levels for the climate change scenario increases moving downstream of Allworth and varies from0.1 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 beincreased 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 andfriction, rather than flood storage. Thus, various increases for design rainfalls will increase flood dischargesand hence flood levels. Guidance on the impact of various increases in flood discharges is given in thesensitivity analysis.

Flood hazard diagrams through the study area for the 5% AEP, 1% AEP and 0.5% AEP floods plus thePMF flood have been prepared and appear as Figures 29 to 40 inclusive. The flood hazard diagrams dividethe inundated area into floodways and flood storage regions. The floodways and flood storage regions areeach sub-divided into “low”, “medium”, and “high hazard” using the criteria specified in the NSWFloodplain Development Manual.



14

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 thirdcategory, “flood fringe” was examined. The criterion for definition of “flood fringe” adopted (for thepurposes of this study) was that flood inundation depths were less than 0.2 metres. Analysis of “floodfringe” 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 toindicate “flood fringe” regions.




15

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 isfollowing the Floodplain Management Process, as outlined in the Foreword and promoted by the NSWGovernment.

The locality of the study area for the Karuah Flood Study is illustrated in a state wide context, and withinthe 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 StroudRoad 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 StroudRoad, follows the confluences of Karuah River with Mammy Johnsons River (315 sq kilometres) and RamStation 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.



16

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 developmentcontrols along the Karuah River in the study area;

- provide downstream flood levels for future flood studies of the villages of Stroud andStroud Road.

A reconnaissance survey of the site and the available data suggests that sufficient hydrological data andrecorded flood levels will be available to establish and calibrate a hydrological model of the catchment (toestimate flood flows) and to establish a riverine model to define flood levels and flood hazard for a varietyof design flood events.

Thus, an appropriate study approach, consistent with the above uses and the constraints outlined inChapter 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 studyarea), 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 theProbable 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 byriverine flooding or ocean induced flooding or a combination of both.




17

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 onsite 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) iscommonly derived from Australian Rainfall and Runoff (Ref. 1). This practice has been followed in thisstudy

3.2 Previous Studies, Documents

There are a limited number of historical documents that have been examined, principally for recorded dataon:

- 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.



18

In the review, it was presumed that the published information can be treated as "reliable" and furtherbackground 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 ofeditions of PINNEENA.

It should be noted that PINNEENA generally contains the digitally recorded information. There isadditional historical flood level information held on the original gauge reader cards that does not appear inPINNEENA.

The most relevant DWE station (previously WRC, DWR and DNR) is Station 209003 “Karuah River atBooral”, 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 theperiod 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 CATCHMENTAREA (SQ KM)

START DATE FINISH DATE

209001 Karuah River atMonkerai

203 1945 1981

209002 Mammy JohnsonsRiver at Pikes

Crossing

156 1967 Current

209003 Karuah River atBooral

974 1968 Current

209004 Mammy Johnsonsat River at Stroud

Road

318 1968 1981

209008 Karuah River atStroud Road

342 1969 1980

209018 Karuah River atDam Site

300 1979 Current

The ranking of five largest historical floods recorded at Station 209003 “Karuah River at Booral” is givenin Table 1 below, whilst the full flood series is given in Appendix A. The data in Table 1 and Appendix A isderived from a combination of PINNEENA and DWE Hydrography Branch records.




19

Table 1

Significant Historical Floods(Station 209003, "Karuah River @ Booral")

(Source: Pinneena Version 9)

Rank Flood Year Peak Flow(cu. m/sec)

Peak Level(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 flowmeasurements 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 metresbelow 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 PacificHighway and Karuah Bypass contained no flood information. However, the drawings for Booral andWashpool bridges do contain some historical data. This historical data is tabulated in Table 2 below.



20

Table 2

Historical Flood Data – RTA Bridges

Item Karuah River @Washpool

Karuah River @ Booral

Drawing Date 1980 1944Datum m, AHD Ft, assumed m, AHD

Deck Level RL 39.56 RL 101 ft 14.28Flood Level: 1850 RL 38.5 -Flood Level: 1894 - 92 ft 11.78Flood 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 ofinterest relate to:

- estimation of 5%, 2%, and 1% AEP flood discharges for the Karuah River at Booraland 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 JohnstonsCreek 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 JohnstonsCreek, Monkerai and Karuah Forest;

- Estimation of catchment average rainfall (using daily rainfalls from available stationsusing Theisen polygons) as:

o Period 20 to 25 January 1976: 153 millimetreso Period 1 to 4 March 1977: 190.95 millimetreso Period 17 to 21 March 1978: 332.74 millimetres

- Flood profile for the 1977 and 1978 floods along the Karuah River derived fromHDWB peak level recorders;

- Location details for the DWR recorder station at Station 209003, “Karuah River atBooral”




21

In the review of the calculation file, it has been assumed that the calculations are arithmeticallycorrect. Thepeak 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 2.5mm 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 aunit hydrograph for the Karuah at Booral, yet relies on a synthetic unit hydrograph to determine designdischarges for the Karuah River at Booral.

It should be noted that Australian Rainfall and Runoff, 1988 (Ref. 1) is substantially different fromthe 1977edition (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(% AEP)

Karuah River @ Booral(cu m/sec)

Karuah River @ Karuah(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 DistrictWater 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.



22

Table 4

Recorded Peak Flood Levels(Source: PWD Calculation File (1981))

Peak Flood Level(m AHD)

Location RiverDistance

(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 ofRL 8.43 m AHD, while the DWR record gives a peak of RL 8.38 m AHD. These discrepancies indicateeither the record may have an incorrect connection to Australian Height Datum or involve an incorrectreading.

Stroud Flood Study, WRC, 1986 (Reference 7)

This report covers a flood study of Stroud undertaken by the then Water Resources Commission. Thereport 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 wasreportedly the 1956 event. The study reduced available flood marks to Australian Height Datum. Therange 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).




23

The two principal water courses through Stroud are Lamans Creek and Mill Creek. These creeks join theKaruah River some 1100 metres downstream of Stroud and some 1500 metres downstreamof the low levelcrossing of the Karuah River near Stroud.

Comparison of the recorded 1985 levels in Stroud and estimated 1985 flood levels in the Karuah River, atthe confluence of the Karuah River and Mill Creek, show the lowest recorded flood level in Stroud to beabout two metres above the Karuah River levels. This implies that Stroud is not affected by Karuah Riverfloods 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 forthe 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 lasttwo reports deal principally with wind driven waves along the Port Stephens foreshores and do not containinformation considered relevant to the Karuah Flood Study.

The Port Stephens Flood Study (Reference 8, the first report above) considered flooding in Port Stephenscomprising:

- runoff from the catchments of the Karuah River, Myall River, Tilligerry Creek and anumber 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 SeaLevel).

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 atKaruah. These peak water levels comprised components of flood inflows, wind waveset-up and ocean levels controlling the entrance of Port Stephens.



24

With regard to the hydrology of the Karuah River, the study:

- established an hydrologic model of the Karuah River to Karuah (Port Stephens) usingthe 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 andsupplemented with daily rainfall data from Craven, Stroud and Tahlee. The DNR station, “Karuah River atBooral” (Station 209003) was used to determine flood volumes, while the more upstream station, “KaruahRiver 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 millimetresContinuing Loss: 0.5 millimetres per hour

- March 1978: Initial Loss: 120 millimetresContinuing 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 meancatchment rainfalls derived from the daily rainfall stations. Thus, the rainfall durations derived were fordurations 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 Lossrespectively.

The long “critical” storm duration was justified in the report as being representative of the calibrationevents, 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 1967to 1980.




25

Table 5 below provides a comparison between the peak flow estimates derived fromthe WBNM modelandthe DWR flood frequency at Booral.

Table 5

Estimated Peak Flood Discharges – Karuah River at Booral(Source: Port Stephens Flood Study, Reference 8)

Peak Discharge(cu m/sec)

Frequency(% AEP)

ReturnPeriod

(yrs ARI)DWR FloodFrequency

WBNM

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 historicalflood frequency (over the period of available record at that time), the WBNM results are a long durationevent, 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 usingMIKE-21 software. This model was used to estimate design peak water levels at Karuah as a combinationof 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 PortStephens, 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



26

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 levelsabove 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, therewill be minimal wave set-up at the entrance.

The design ocean levels (in Table 6) at Port Stephens were derived by combining the astronomical tide withstorm surge values derived from historical storms.

It should be noted that the values quoted in Table 6 represent a concurrent occurrence between the peak ofthe design 5 day hydrograph in the Karuah River and the peak of the astronomical tide. The report alsonotes that the 3 day hydrograph created a peak level that was only 30 millimetres lower than the 120 hourstorm.

Similarly, the report (Table 11.1, Reference 8) notes that the Karuah River at Karuah is not subject toocean 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 +wind + set-up) 2

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 82. Source Table 8.1, Reference 83. Source Table 6.1, Reference 84. Source Table S1, Reference 8




27

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 eventsrather 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 thecalibration events, yet used low initial loss values (derived from AR&R) as opposed tothe large initial losses identified in the calibration events;

- The study was directed to prediction of flood levels in Port Stephens, which, becauseof the size of its catchment, will respond to rainfall over days rather than 24 hours orless. The Study focus will thus concentrate on the long duration events rather than theshort 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 atBooral only over the period 1967 to 1980, notwithstanding that flood data for theperiod 1967 to 1996 should have been available;

- it is also surprising that the Flood Study did not reference the 1985 flood, which wasapproximately 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 early1900’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 the1890’s.

Hunter District Water Board

The Hunter District Water Board (the predecessor of Hunter Water) investigated drawing water suppliesfrom the Williams River (at Seaham Weir) and from the Karuah River near Booral. As part of thoseinvestigations, 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 DWRrecords.



28

The reports tabulate a series of peak levels reached for the above floods. The reports identify the floodlevels 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 anapproximately 1:50 000 scale plan. The Hunter Water records indicate some survey was undertaken withthe 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

Peak Level (m AHD)HDWBIdentification Location

January 1976 March 1977 March 1978

1. Karuah River,Washpool Bridge No Reading 33.86 37.75

2. Karuah River, Stroud 22.15 24.04 25.10

3. Karuah River, Stroudto Booral 12.93 15.06 16.44

4. Karuah River, Booral 6.32 8.43 9.26

5. Karuah River,Allworth Weir Site 3.02 4.93 5.87

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 hydrographyrecords as part of the hydrographic network. The bulk of the relevant information, but not all availabledata, is published as “PINNEENA”, referenced above.




29

The river height information is held by DWE. It is converted to flow data via rating tables established bymeasuring flow at discrete times when a technical officer visits the Gauging Station. Height informationwas originally collected manually by gauge readers living near the Gauging Station, usually on a daily visitto the site (often at 9am). Automatic recorders were installed later and offer continuous records. Thesecontinuous 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 thereaches of the Karuah River subject of this Study. It has the benefit both of high gaugings and of areasonably stable stream. The highest gauging (No. 63) was taken in 1977 at GH 6.06 m (about 3 m belowthe 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 beenattempted on 27 May 1974 at GH 5.35 m but was not adequate for rating purposes. It was repeated thenext 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 atlevels 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 notesuggested those velocities be used for rating extension. Calculations yield flows that appear to have beenused for the rating table adopted by DWE. This is reasonable as the River’s cross-section around the site isregular and heights recorded to date have not exceeded bank-full level. The rating table is accepted and theDepartment’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 floodingconcurrent with the Karuah River itself.);

b) After its establishment but prior to continuous recording (commenced in August 1971): January1971;

c) After installation of a continuous water-level recorder: as in Table 8 below.



30

Table 8

Ranked Flood Series 1969 to 2007 – Karuah River At Booral

Peak Level Peak Flow

Rank Date Time G H2 (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 records2. 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 floodas the highest recorded in the Paterson, Allyn, Williams and Karuah Rivers. Many of the WC&IC gaugesused 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 apeak flow of 971 cu m/second listed for 1 March 1963 as the highest level recorded before the Station wasclosed in July 1981. It was replaced by Stn 209018 “Karuah River at Damsite #3” just downstream ofMonkerai.




31

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 thatoverbank 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 andused to determine the maximum height to which gauges should be installed. It is not considered definitiveenough 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 October1974, estimating that the location acted as “control” for Station 209003 in high events. The surveyrecordsa 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 Booral indicates alevel of 92’ for the 1894 flood, presumed the highest known in 1944. That flood level measures 0.99 mbelow soffit level on the drawing. Using the soffit level from the DWE’s 1974 survey gives a flood level for1894 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, some20 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 thatthe ground survey of Karuah immediately upstream of the gauge at Booral shows the top of bank atRL 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 sourcehowever, 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 database. The listing of the daily rainfall stations and pluviometers is reproduced as Appendix B, while theirpositions are plotted on Figure 3.

It will be noted:

- from Figure 3, there are only seven daily rainfall stations in the Karuah Rivercatchment;

- from Appendix B, there are only two daily rainfall stations that are currentlyoperational (Stroud and Wallaroo State Forest);



32

- from Figure 3, there are no pluviometers on the catchment and the nearest instrumentsare 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(Wallaroo State Forest)

1938 Daily

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 alongthe riverine corridor within the study area. Sixty eight (68) questionnaires were returned, though noneprovided information to justify the cost of ground survey to level any flood marks to Australian HeightDatum (AHD).

A “doorknock” program was undertaken upstream of Booral to identify long term residents and todetermine 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 thelocations 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.

Paterson Consultants Pty Limited 33


Final Report - November 2010R90\07012.V8

Table 10

Results of Additional Survey from Resident Interviews

Co-ordinates (MGA)E N

River Distance(m)

Level(m AHD)

Flood Year Comment

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



34

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 thestudy 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 of flooding and aschecks 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 of predictedflood inflows to the riverine system;

- development of appropriate "design" rainfall volumes and rainfall temporal patterns sothat "design" hydrographs resulting from the "design rainfall" can be derived;

- flood frequency analysis of historically recorded flood events to enable extrapolation torarer or "design" events and as a cross-check against the results of the hydrologicalmodel.

The above three aspects are addressed below.

It should be noted that the assumption that "design rainfall of a particular frequency (return period) willcreate a flood of the same frequency", is implicit in the above approach. Such an assumption is reasonablein 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 of similar size to the KaruahRiver 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 unithydrograph techniques or time-area diagrams.




35

Previous flood studies of the Karuah include “Port Stephens Flood Study” of July 1996 by ManlyHydraulics Laboratory for Port Stephens and Great Lakes Shire Councils (Ref. 8). That study examinedflooding 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 GaugingStation 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 betterevents for calibration as opposed to January 1971;

- parts of the sub-catchment layout, when used in a WBNM model, indicated little floodflow 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 notionalstorages (representing individual river reaches). The same sub-catchment layout as used in Reference 8 hasbeen used for the RORB model

Calibration of the model was undertaken for Gauging Station 209003 “Karuah River at Booral” using thehighest three floods recorded with good flow data as well as good rainfall data from pluviographs atChichester Dam and at Williamtown RAAF Base. The floods identified were 1978, 1990 and 2001. Twoother 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 evidentthat 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 Rivercatchment. They are taken to represent the upper and lower parts of the catchment, respectively. In eachof the three events adopted for model calibration, rainfall varies between the coast and inland but notconsistently. The comparative 4-day total rainfalls are listed in Table 11 below.



36

Table 11

Comparative 4-day Total Rainfalls

Event Flood Rank1 Chichester Total(mm)

Williamtown Total(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 coastthan inland for short duration storms but the opposite for long durations. The 1978 and 2001 eventsconform 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 pointcorresponds to a location between Stroud and Stroud Road.

Calibration was undertaken by varying model parameters to achieve best fit of the synthesised hydrographto that measured at Booral. Peak flow rate should be a reasonable match as well as hydrograph shape. Theprincipal parameters required to achieve model calibration are routing parameters (kc and m) and the rainfallloss model adopted. As only three floods are tested and as there are no unusual features to the Karuahcatchment, a standard value of 0.8 is adopted for parameter ‘m’. All three floods demonstrated their best fitwith 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 1990and zero in 2001). In the 1977 and 2007 floods, the continuing loss was ascertained at 0.8 and1.80 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 goodaverage of the calibration runs and a value often suggested when no other is available.




37

Initial Losses varied for each of the three historical rainfall events, according to how early or late in theevent data was considered to be included. It is therefore somewhat arbitrary. Falls up to about the time ofrise 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 2007events). 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, whileFigures 5, 6, 7 and 8 illustrate the comparison.

In the 2001 event a hydrograph was also recorded well upstream of Booral, at Station 209018 “KaruahRiver at Damsite #3”. That information is included in testing for parameters and its fit is also presented inFigure 7.

Table 12

Comparison of Modelled and Recorded Peak Discharge(Karuah River at Booral)

Peak Discharge (cu m/sec)Flood

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 theChichester and Williamtown pluviographs produced discrepancies in the 1977 event in that the modelledflood hydrograph is a single peak feature, while the recorded flood hydrograph is a distinct double peakevent.

The best fit between the recorded and modelled hydrographs was derived by:

- changing the assumed daily rainfall distribution whilst maintaining consistency of therecords at individual stations;

- changing the assumed distribution of the available pluviographs;

- treating each day of rainfall as a separate burst with separate continuing loss ratesassumed for each burst.



38

A reverse problem was experienced with the 2007 flood, where the recorded event is a single peak floodwith a steep recession curve, while the initial modelled results indicated a double peak with a gradualrecession. The best fit for the 2007 event (as shown on Figure 8) was achieved using the same technique ofa 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 ofrainfall distribution across the catchment. At this point, there is not enough data to enable a betterassessment 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 floodproducing rainfall events.

4.3 Design Flood Hydrographs

For design runs of the RORB model, intensity-frequency-duration (IFD) data was derived according toAR&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, thoseinland design intensities were generally about 15% higher than coastal. Given this relatively smalldifference (compared with much larger variations such as those seen on the above Table 11 for thecalibration 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 coastalones.

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 andtemporal 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 from50% AEP (1-in-2-year ARI) to 0.5% AEP (1-in-200-year ARI). Various stormdurations (varying between12 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 couldbe used for all intents and purposes.

Table 13 below lists the peak flood discharges as derived using the RORB model with various return periodrainfalls for the Karuah River at Booral and at Karuah.




39

Table 13

Peak Discharges – Design Floods(Source: RORB model using ARR rainfall)

Frequency Peak Discharge(cu m/sec)

AEP(Percent)

ARI(yrs)

Karuah Riverat Booral

Karuah Riverat 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 10for the various tributaries to the Karuah River, while Figure 11 illustrates the predicted total flow in theKaruah 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 ProbableMaximum Precipitation (PMP).

The PMP has been defined by the World Meteorological Organisation (1986) as “the greatest depth ofprecipitation for a given duration, meteorologically possible for a given size storm area at a particularlocation 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 estimationof PMP rainfall in Australia.

Broadly, the Bureau advocates the use of one of three methods, subject to the catchment size and thelocation of the catchment.



40

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 asbeyond 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 Meteorologyguide 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(mm)Storm Duration

(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 hourGDSM method and the 24 hour duration rainfalls listed in Table 14 above. Such interpolation gives the12 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 theKaruah River at Booral and Karuah as listed in Table 15 below.




41

Table 15

Peak Discharges - PMF(Source: GSAM Method)

Peak Flow(cu m/sec)Storm Duration

(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 hourduration. 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 hourstorm at Booral;

- the 24 hour event, having a larger flood volume, should have more storage routing, asthe flood passes through the river system. This difference will be demonstrated by thehydrodynamic model.

In comparison between the “critical” duration for the PMF (24 hours as above) versus the more frequentdesign storms (36 hours, as outlined earlier), it should be noted that the estimated floods produced are verydependent on the rainfall temporal pattern applied and that the temporal patterns from Australian Rainfalland Runoff (Reference 1), as applied to the design storms, are different to those recommended by theBureau of Meteorology for the PMF estimation.

Figure 12 provides a comparison between the PMF hydrographs and the design 1% AEP flood hydrographsat 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;



42

- estimate the recurrence interval for a particular historical flood;

- extrapolate flood behaviour beyond the historical record or interpolate within thehistorical 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 exhibitsdiscontinuities 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" wasthus:

- conversion of flood heights from a gauge reading to flood discharge using theappropriate 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 toboth Log Pearson III (LPIII) distribution and the Generalised Extreme Value (GEV)distribution.

Both Log Pearson III and Generalised Extreme Values are mathematical statisticaldistributions widelyusedfor flood frequency analysis.

The plotted flood frequency appears on Figure 9 (for both LPIII and GEV distributions). Figure 9 alsoillustrates 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 IIIdistribution, are given in Table 16 below;

- the actual historical floods plot below the Log Pearson III distribution and the GEVdistribution (with a 1% AEP peak discharge of about 800 cu. m/sec);




43

- in fitting the Log Pearson III distribution, the complete annual series is used and thusthe historical data plots lower than the distribution for rare floods and above thedistribution 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% confidencelimit;

- the flood frequency has been derived by “Method of Moments” using logarithmof 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)

Confidence LevelAEP(percent)

ARI(yrs)

Log Pearson IIIDistribution – 5% + 5%

0.5 200 3,634 1,583 8,3461.0 100 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



ARI(yrs)

GEV Distribution– 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



44



ARI(yrs)

GEV Distribution– 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 modellingproduce a variety of flood flow estimates for the Karuah River at Booral. The flow estimates are listed inTable 17 below.

Table 17

Comparison of Peak Flows, Karuah River at Booral

Historical Sourced Information This StudyFrequency(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 3.22. Reported in Reference 8, 1967 to 1980 – Refer Section 3.23. Reference 8 – Refer Section 3.24. Section 4.5 of this Study5. Section 4.3 of this Study

Comparison between the design flood discharges (derived in this study) produced by the RORB model forthe Karuah at Booral and peak discharges produced by the frequency analysis of the historical record (asindicated by Table 17 above and Figure 12) shows the RORB model as producing reasonable results fordesign 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.




45

5. HYDRODYNAMIC INVESTIGATION

5.1 Overview

The object of the hydrodynamic models is to convert flood hydrographs to flood levels at particularlocations.

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 control along the Karuah River.

Given the above topographic considerations and the end use of the flood study, a one-dimensionalhydrodynamic 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 theconsultant’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 toKaruah.

- 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 thetwo 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 crosssections were selected so that reasonable estimates of waterway area and flood storage would be derived inthe MIKE-11 model.



46

It is noted that:

- The road bridges across the Karuah River at Stroud Road and Stroud are low level andwithout 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 abovelikely flood levels and thus will not affect flood behaviour.

- The road crossings of the Karuah River at Washpool (Stroud-Dungog Road) andBooral and the railway bridge and its approach bridges at Stroud Road are slightlyelevated above the floodplain and have elevated approaches. Thus, they will affectflood behaviour for floods higher than the “top of bank” for the Karuah River and havebeen included in the MIKE-11 model.

Table 18 below tabulates the surveyed cross-sections and the assigned distances (“river distance” plusidentified 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





47


K8 13,061

Confluence, Mill Creek NS 13,973

K9 14,003

K10 14,714

K11 16,229


Confluence, Alderley Creek NS 18,513

K12 18,774

K13 19,733

K14 21,247

Bucketts Way bridge, Booral S3 , K15 21,902


K16 22,360

Confluence, Booral Creek NS 23,170

K17 23,218

K18 24,718

K19 25,278


K20 26,822

K21 27,861

Allworth, Upstream NS 31,030

K22 31,145

Boat Ramp, Allworth NS 31,542


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



48


Karuah Bridge, Pacific Highway NS 47,013

End of model NS 47,029

Notes: 1. Cross-sections K1 to K28 surveyed for this study2. Cross-sections S1 to S3 surveyed for this study as part of bridge detail surveying3. 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 Railo 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 thePort Stephens water levels.

Table 19 lists the hydrograph inputs and the input river distance.




49

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 design1% AEP, 36 hour design storm.

The tailwater levels used in Port Stephens vary for each historical flood and design flood tested. Derivationof the tailwater levels for Port Stephens is addressed in the following sections dealing with modelcalibration – 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 Station209003 “Karuah River at Booral”;

- historically “recorded” peak levels from bridge structures (3 levels) with two historicalpeak levels from resident interviews.



50

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 12indicates a good fit between the RORB model and the modelled flows and the recordedflows.

- The 1977 and 2007 floods were also tested with the RORB model, which produced areasonable comparison between recorded and calculated levels.

- The recorded water levels for the HDWB peak level indicator at Booral are higher thanthe DWR Station 209003 “Karuah River at Booral” notwithstanding that the HDWBgauge appears to be some 50 metres downstream of the DWR gauge. For example, theHDWB peak levels for 1976, 1977 and 1978 were 6.32 m AHD, 8.43 m AHD, and9.26 m AHD respectively compared to the DWR records of 6.32 m AHD, 8.38 mAHD and 9.03 m AHD respectively.

- The modelled hydrographs for the 1978 and the 1990 floods match the shape of therecorded hydrographs quite well. However, the 2001 modelled hydrograph shows adouble peak event as compared to the single peak event recorded. The reverse appliesto the 1977 event, where the modelled peak is a single peak event, while the recordedevent was a double peak (see Figure 5). The initial rise in the 1990 flood (seeFigure 6) is not well reproduced by the RORB model, while the comparison betweenthe modelled and recorded flood is satisfactory for the second peak (the moresignificant flood rise). Iterative testing of the application of recorded pluviographs andloss rates in the RORB model has shown these discrepancies are the result of theuncertain rainfall distribution across the catchment.

In summary, there is reasonable water level and discharge data at Booral (Station 209003) but little floodlevel 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 “KaruahRiver at Booral”.

- Testing with the 1978 and 1977 flood to confirm the longitudinal profiles, mindful thatpeak 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;




51

- the design one percent AEP flood levels are not significantlydifferent tothe highest recorded flood levels noted on the various bridge drawings.This approach assumes that the highest recorded floods are likely to bein the range of the two percent AEP to one percent AEP, given there isat least some 100 years of resident knowledge available (through oralhistory).

For the MIKE-11 model calibration and verification, the tailwater levels at Karuah were either predictedtide 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 Stephenslevels 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 reproducesthe rating curve satisfactorily.

Figures 19 and 20 show the calculated flood profiles for the 1977, 1978 and 2007 floods, while Figure 21indicates a comparison of recorded and calculated peak levels at Booral for the 1977, 1978, 1990, 2001 and2007 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 RiverDistance

(m)

Recorded FloodLevel

(m AHD)

Calculated FloodLevel

(m AHD)

Difference(m)

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

1977

HDWB#6 31,740 1.64 2.16 0.52

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

1978

HDWB#3 17,401 16.44 16.78 0.34



52


(m)

Recorded FloodLevel

(m AHD)

Calculated FloodLevel

(m AHD)

Difference(m)

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

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

2007

Station 209003 21,901 8.42 8.47 0.05

Table 21

Comparison of Historical Levels and Design Flood Levels


(m)

RecordedFlood Level(m AHD)

Design 1%AEP

(m AHD)

Difference(m)

Resident 2,930 > 40.55 (1988?) 2 41.54 < 0.99

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

Resident 5,315 > 36.4< 38.1 39.12 < 2.48

> 1.02RTA –Washpool 5,926 38.5 (1950) 2

37.1 (1946) 2 38.26 -0.241.16

Resident 12,586 26.63 (1955) 2 27.32 0.69

Other HistoricalFloods

RTA – Booral 21,901 11.78 11.48 -0.30

Notes: 1. Mark on south pier2. Bracketted figures give approximate date3. Located on flood runner, lower than top of bank at this point




53

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 (asillustrated by the difference between the recorded and model hydrographs at BooralonFigure 5);

- the MIKE-11 results for the 1978 event are expected to be a better match for therecorded flood levels, as the match between the RORB model and the recorded flowsat Booral is better than the 1977 event.

- there may have been some transposition errors in creating the HDWB reports fromtheoriginal 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 themodel did not enable agreement between the calculated flood levels and the HDWB records to be reachedat:

- 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 bridgestructures indicates that the MIKE-11 values, as derived from the historical floods, are of the correct order.

By chance, the site inspections identified the HDWB #2, downstream of the low level road crossing atStroud. 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 levelreading 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 withStation 209003 “Karuah River at Booral” indicates that the peak level indicator station could be upstreamof 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-11model. The Mannings `n’ value adopted for various branches not specified in Table 22 was 0.045. Thevalues in Table 22 represent the ‘main channel” values, while overbank areas have been specified as themain 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 totalstorm rainfall and rainfall patterns, the comparison between the recorded and calculated flood level valuesfor the 1977, 1978, 1990, 2001 and 2007 floods is considered satisfactory.



54

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




55

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 theKaruah River by:

- application of the various tributary inflows into the Karuah River through the studyarea 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 isaddressed 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 tochange 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 of thisreport.

6.2 Design Tailwater Levels

The downstream boundary of the Study Area is at Karuah. At this point, water levels in the Karuah Riverare 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 of thisstudy) have been categorised as:

- River flooding (caused by runoff);- Ocean flooding (caused by elevated ocean water levels).



56

The flooding scenarios are not directly related and thus, common practice is to derive design flood levels asthe 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 isRL 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 metresMaximum 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 FloodStudy. 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) whilethe 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 probabilityplotting.

Figure 22 indicates the adopted maximum tailwater at Karuah applied to the semi-diurnal astronomicalocean 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 levelsat Karuah, comprising ofcoincident occurrence of ocean tide, wind set-up and stormsurge, reaching a peaklevel 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 theProbable 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 levelconditions at Port Stephens, with a peak level of RL 1.06 m AHD, thus no correlationbetween river flooding and ocean storm surge has been implied;

- where the design flood levels produced by MIKE-11 are less than the ocean floodingconditions adopted in the Port Stephens Flood Study (Reference 8), the higher floodlevels have been used to override the MIKE-11 results. This approach ensures that thedesign flood levels represent an envelope of possible events.




57

- typically, the PMF flood varies between 5 and 9 metres above the design 1% AEPevent upstream of Booral and up to 5 metres above the design 1% AEP eventdownstream of Booral;

- typically, the design 0.5% AEP event is up to 1 metre higher than the design 1% AEPevent, depending on location;

- the existing RTA bridges are above the design 1% AEP event, though they will beovertopped in a PMF event. The 0.5% AEP floods will inundate the underside of thebridges but not overtop the bridge deck.

- The reaches of the Karuah River downstream of its confluence with The Branch areaffected by the prevailing water level in Port Stephens. This point is demonstrated bythe diminishing differences between the eight design floods as the Karuah reaches PortStephens.

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 forthe Karuah River near Stroud.

Table 23

Design Flood Levels, Karuah River

Karuah RiverReturnPeriod

(%AEP)

At Karuah1

(m AHD)At Allworth

(m AHD)

At Booral(m AHD)

At MillCreek

Confluence(m AHD)

At RTABridge at

“Washpool”(m AHD)

At RailBridge Stroud

Road(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



58

7. SENSITIVITY ANALYSIS

The design flood levels outlined in Chapter 6 rely on the hydrodynamic model (MIKE-11), which itself isinfluenced 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 onthe design 1% AEP flood event with a varying tailwater level at Karuah, with a peak level of RL 1.06 mAHD, 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 indischarge;

- 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 thedesign 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 tidalcycle and the minimum tide level in the tidal cycle;

- simple increases of 20 percent for design inflows into the MIKE-11 model and 20percent increase in the friction allowances in the MIKE-11 model (as represented byMannings `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 amaximum tidal level of 0.9 metres at Port Stephens. This event has been used as thebase case for comparison.

- The 1% AEP 36 hour design event with the peak river flood coincident with theminimum tidal cycle level. This test, with comparison to the previous test, indicates theeffect of the tidal cycle propagating upstream.

- The design 1% AEP 36 hour design event, concurrent with the 0.9 metre tidal leveltogether with a 0.8 metre allowance for a climate change induced ocean level rise (themaximum predicted by IPCC for the projection period to 2090/2099).




59

- The 1% AEP flood with the inflows factored by 1.2, to represent a 20% increase inflows as a measure of the sensitivity of design flood levels to changes of thismagnitude;

- The 1% AEP flood using the MIKE-11 model with the friction in the model (thedominant 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 modelfriction 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 theMIKE-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) plus17 percent flow (the 0.5% AEP), the flood levels vary between 0.44 metres and 1.0 metres upstream ofAllworth.

Similarly, for the base case (1% AEP) less 17 percent flow (the 2% AEP), the design flood levels upstreamof Allworth vary between -1.11 metres and -0.46 metres. The greatest difference in flood levels betweenthe base case plus 17 percent (0.5% AEP) and the base case less 17 percent AEP occur between theconfluences 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 asthose 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 TheBranch confluence. The maximum difference in flood levels is of the order of0.4 metres. The last 4 kilometres of the Karuah River indicate the influence of thepeak tidal level, even though the design flood has been adjusted such that the peakriver flood occurs concurrently with the minimum levels of the tidal cycle.



60

- In the last 3 kilometres of the Karuah River, under current (2008) conditions, floodlevels for a design 1% AEP event are controlled by the ocean level, while upstream ofthis point, flood levels are controlled by river flooding;

- The impact of climate change induced increases in ocean level will occur as farupstream as Allworth, though the more severe increases (above 0.20 metres) occurdownstream of The Branch confluence. The predicted rise in flood levels diminishesmoving upstream from 0.8 metres at Port Stephens to 0.1 metre at Allworth.




61

8. PRELIMINARY ASSESSMENT OF CLIMATE CHANGE IMPACTS

This chapter presents a preliminary analysis of the impact of climate change on ocean level and rainfallsusing information as was available in September 2008. Further assessment will need to be undertaken forthe 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 significantchanges to the current situation are likely to be:

- an increase in mean sea level, giving higher tailwater levels for the Karuah River atKaruah;

- 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 levelincreases over the period 1980/1990 to 2090/2099 for various scenarios of continuing “greenhouse” gasemissions. The smallest ocean increase (IPCC Scenario B1) is 0.18 m to 0.38 m over the projection period.The largest increase (IPCC Scenario A1, F1) is 0.26 metres to 0.59 metres over the projection period plusa 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 regionsof Australia. There is a wide range of predictions relating to the emission scenario, projection period andmodel used.

Over the Karuah catchment, the Technical Report (Reference 22, Chapter 5) indicates that the change inintense 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 higherthan the predicted climate change by this reference, an appropriate response for this study is to maintain theexisting daily rainfall intensity data and to account for rainfall changes through application of freeboard todesign flood levels.

The Department of Environment and Climate Change has issued a guideline “Practical Consideration ofClimate Change”, October 2007 (Reference 22), which opines a sea level increase of 0.91, comprising0.79 metres derived from the IPCC Reports together with a component of 0.12 metres derived bya CSIROstudy as a regional sea level rise variation along the NSW coast due to changes in the East Australian oceancurrent. Reference 22 also opines a potential change in extreme daily rainfall for the Hunter region as a –7percent to +10 percent change from current values. The reference also recommends sensitivity analysis forrainfall increases of 10, 20 and 30 percent from current values.

The NSW Government has recently issued a “NSW Sea Level Rise Policy Statement” which indicatesplanning bench marks that indicate a mean sea level rise (from 1990 mean sea levels) of 40 centimetres by2050 and 90 centimetres by 2100.

The bulk of the Karuah River experiences flooding from runoff. In the previous chapter, “SensitivityAnalysis”, design analysis is undertaken for a 20 percent increase in river flows. This case, presented on



62

Figures 26 and 27, is similar to the impact of an increase in rainfall of 20 percent. Rainfall increases of thismagnitude 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 floodingcaused 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, (tailwaterlevel 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 wouldreach 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 inthe Karuah River upstream of Karuah to Allworth.




63

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 the5% 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 “FloodplainDevelopment 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 betransferred 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 fromAerialLaser Survey (ALS) data. The ALS data produces about four million data points persquare kilometre. The averaging process used reduces the number of points to a moremanageable 10,000 points per square kilometre (totalling some 470,000 points over thestudy area).

- the individual design flood surfaces were created by extrapolation of the MIKE-11results 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 HighHazard 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 andfloodways with the hydraulic categories (from Figure L2 of Reference 3) with respectto the above;

- flood fringe areas were defined (for the purposes of this study) as area where flooddepths were less than 0.3 metres. In reality, this test showed very few areas would beclassified 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 storagewas 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 offlood fringe and obvious flood storage.



64

It is noted that, given the approach to identify flood levels over a relatively long area using widely spacedcross-sections (undertaken to reduce overall project cost), definition of small floodways using the floodwayblockage 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 thenecessary extension of flood surfaces.

- in areas where a more precise definition of flood hazard is required, ground truthingand finer scale definition of flood extents should be undertaken on a case to case basis.




65

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 inAustralia: Generalised Short-Duration Method", June 2003

5. Cordrey & Webb, “Flood Estimation in Eastern New South Wales, A Design Method”, Institutionof 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 WaveClimate”, July 1996

9. Manly Hydraulics Laboratory, “Port Stephens Flood Study – Stage 3 Foreshore flooding”, October1997

10. Webb McKeown & Associates Pty Ltd, “Port Stephens Foreshore (Floodplain) ManagementStudy”, 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 – WaterMarch 1976.



66

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 EngineeringConference, 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




67

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 (seeaverage recurrence interval).

annual flood seriesis comprised of the highest instantaneous rate of discharge in each year of record. The highest flow in eachyear 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 floodprone area. AAD is the average damage per year that would occur in a nominated development situationfrom 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, theselected event. For example, floods with a discharge as great as, or greater than, the 20 year ARI floodevent will occur on average once every 20 years. ARI is another way of expressing the likelihood ofoccurrence of a flood event. This is the inverse of AEP and does not reflect the time elapsed betweenfloods.

Floodplain Management Manualthe management of flood liable land development is defined in Part 4 of the Environmental Planning andAssessment Act (EP&A Act).

disaster plan (DISPLAN)a step by step sequence of previously agreed roles, responsibilities, functions, actions and managementarrangements for the conduct of a single or series of connected emergency operations, with the object ofensuring the coordinated response by all agencies having responsibilities and functions in emergencies.

dischargethe 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 ismoving for example, metres per second (m/s).



68

GLOSSARY - Terms and Abbreviations (Cont)

ecologically sustainable development (ESD)using, conserving and enhancing natural resources so that ecological processes, on which life depends, aremaintained, and the total quality of life, now and in the future, can be maintained or increased. A moredetailed definition is included in the Local Government Act 1993. The use of sustainability and sustainablein this manual are related to ESD.

effective warning timethe time available after receiving advice of an impending flood and before the floodwaters preventappropriate flood response actions being undertaken. The effective warning time is typically used to movefarm equipment, move stock, raise furniture, evacuate people and transport their possessions.

flash floodingflooding which is sudden and unexpected. It is often caused by sudden local or nearby heavy rainfall. Oftendefined as flooding which peaks within six hours of the causative rain.

flood fringe areasthe remaining area of flood prone land after floodway and flood storage areas have been defined.

flood liable landis 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 partbelow the flood planning level, as indicated in the 1986 Floodplain Development Manual (see floodplanning area).

flood mitigation standardthe average recurrence interval of the flood, selected as part of the floodplain risk management process thatforms the basis for physical works to modify the impacts of flooding.

floodplainarea 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 locallevels. 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 infloodplain risk management studies and incorporated in floodplain risk management plans. The concept offlood planning levels supersedes the "standard flood event" of the 1986 edition of the FloodplainDevelopment Manual.




69


flood prone landis land susceptible to flooding by the probable maximum flood (PMF) event. Flood prone land issynonymous with flood liable land.

flood riskpotential danger to personal safety and potential damage to property resulting from flooding. The degree ofrisk varies with circumstances across the full range of floods. Flood risk in this manual is divided into 3types, 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 thefloodplain.

continuing flood risk: the risk a community is exposed to after floodplain risk management measures havebeen implemented. For a town protected by levees, the continuing flood risk is the consequences of thelevees being overtopped. For an area without any floodplain risk management measures, the continuingflood risk is simply the existence of its flood exposure.

flood storage areasthose parts of the floodplain that are important for the temporary storage of floodwaters during thepassageof a flood. The extent and behaviour of flood storage areas may change with flood severity, and loss offlood storage can increase the severity of flood impacts by reducing natural flood attenuation. Hence, it isnecessary to investigate a range of flood sizes before defining flood storage areas.

floodway areasthose areas of the floodplain where a significant discharge of water occurs during floods. They are oftenaligned with naturally defined channels. Floodways are areas that, even if only partially blocked, wouldcause a significant redistribution of flood flow, or a significant increase in flood levels.

freeboarda factor of safety typically used in relation to the setting of floor levels, levee crest levels, etc. It is usuallyexpressed as the difference in height between the adopted flood planning level and the flood used todetermine the flood planning level. Freeboard provides a factor of safety to compensate for uncertainties inthe estimation of flood levels across the floodplain, suchand wave action, localised hydraulic behaviour andimpacts 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.



70


hazarda source of potential harm or a situation with a potential to cause loss. In relation to this manual the hazardis flooding which has the potential to cause damage to the community.

hydraulicsterm given to the study of water flow in waterways; in particular, the evaluation of flow parameters such aswater level and velocity.

hydrographa graph which shows how the discharge or stage/flood level at any particular location varies with timeduring a flood.

hydrologyterm given to the study of the rainfall and runoff process; in particular, the evaluation of peak flows, flowvolumes and the derivation of hydrographs for a range of floods.

local overland floodinginundation by local runoff rather than overbank discharge from a stream, river, estuary, lake or dam

Manual or Floodplain Development ManualThe New South Wales Government publication "Floodplain Development Manual", 1986

mathematical/computer modelsthe 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 betweenrunoff, stream flow and the distribution of flows across the floodplain.

partial flood seriesconsists of all floods with peak discharges above a selected base value, regardless of the number of suchfloods occurring each year.

peak dischargethe 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 probablemaximum precipitation. Generally, it is not physically or economically possible to provide completeprotection against this event. The PMF defines the extent of flood prone land, that is, the floodplain. Theextent, nature and potential consequences of flooding associated with the PMF event should be addressedin a floodplain risk management study.




71


probable maximum precipitation (PMP)the greatest depth of precipitation for a given duration meteorologically possible over a given size stormarea at a particular location at a particular time of the year, with no allowance made for long-term climatictrends (World Meteorological Organisation, 1986). It is the primary input to the estimation of the probablemaximum flood.

probabilitya statistical measure of the expected chance of flooding (see annual exceedance probability).

profilea graph showing the flood stage at any given location along a water surface profile watercourse at aparticular time

rating tablea relationship between flood level (as measured by gauge height) and flood flows, usually derived usingactual flow measurements

Reduced Level (RL)a measured height above Australian Height Datum

riskchance of something happening that will have an impact. It is measured in terms of consequences andlikelihood. In the context of the manual it is the likelihood of consequences arising from the interaction offloods, communities and the environment.

runoffthe amount of rainfall which actually ends up as streamflow, also known as rainfall excess.

stageequivalent to "water level". Both are measured with reference to a specified datum.

stage hydrographa graph that shows how the water level at a particular location changes with time during a flood. It must bereferenced to a particular datum.

wind fetchthe horizontal distance in the direction of wind over which wind waves are generated.



72


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




FIGURES

NSW

FIGURE 1STUDY LOCALITY

GREAT LAKES COUNCILKARUAH RIVER FLOOD STUDY

DISK REF: 07012FIG REF: 07012_1_STUDY LOCALITY_V1

10 APR 2008

NEWCASTLE

PORT MACQUARIE

KEMPSEYTAMWORTH

Dungog StroudBuladelah

Muswellbrook

Singleton

Scone

Murrurundi

Nundle

Walcha

Gloucester

Wauchope

Kew

WinghamTaree

Nelson BayHexhamCessnock

Wollombi

TuncurryForster

Oxley

Highway

Hwy

Paci

f ic

Buc k

ett s

WayN

ewE ngland

Hwy Karuah

MAITLAND

Legend

Study CatchmentRoadsTowns

0 5 10FIGU

RE

2ST

UD

YC

AT

CH

ME

NT

6A

UG

2007D

ISCR

EF

:0

7012F

ILE

RE

F:07

012_2_CA

TC

HM

EN

T_V

1

GR

EA

TL

AK

ES

CO

UN

CIL

KA

RU

AH

RIV

ER

FLO

OD

STU

DY

Ward s

R iv er

Ram Station Creek

Karuah RiverM

i l l Creek

Mam

my

Lamans Creek

Booral

The Br

anch

Li me bu rn ers

Karuah

Bulahdelah

Johnsons

River

Creek

River

Stroud

Stroud Road

Allworth

Pacific

Highway

Port Stephens

AlderleyCreek

TelegheryRiver

Buckets

Way

To Gloucester

To Dungog

To Raymond Terrace

To Taree

BooralCreek

Caseys Creek

KaruahRiver

Legend

Catchment BoundaryRoadsScale (kilometres)

61390

61379

61078

61311

61283

61034

61046

61035

61405

61250

61096

61349

61038

61160

61361

61010

61339

61059

61184

61227

61267

61106

61302

6117061045

61340

60008

60042

60062

60003

60033

6014360148

60002

61002

6012361072

6128161395

61303 61054

61350

61332

61169 61364

61122

6115160089 60096

61076

61071

FIGU

RE

3R

AIN

FAL

LST

AT

ION

S27

OC

T2008

DISC

RE

F:

07012

FIL

ER

EF:

07012_3_R

AIN

FAL

L_ST

NS

.V2

GR

EA

TL

AK

ES

CO

UN

CIL

KA

RU

AH

RIV

ER

FLO

OD

STU

DY

War ds

Riv er

Ram Station Creek

Karuah RiverM

il l Cr eek

Mammy

Lamans Creek

Booral

L imeb urn er s

Karuah

Bulahdelah

Johnsons

Ri ver

Creek

River

Stroud

Stroud Road

Allworth

Pacific High

way

Port Stephens

Alderley Creek

TelegheryRiver

Buckets

Way

To Gloucester

To Dungog

To Raymond Terrace

To Taree

BooralCreek

Caseys CreekKar uah

River

The

Bran

ch

Legend

Catchment BoundaryPluviometer StationDaily Rainfall Station

Scale (kilometres)

0 5 10

Current, commenced before 1930Current, commenced after 1930 and before 1980

Tidal water level Station (MHL)

'Mallabula' 'Tomaree'

FIG

UR

E 4

RO

RB

MO

DE

L L

AY

OU

T

15 A

UG

2008

DIS

C R

EF

: 07012

FIL

E R

EF

: 07012_4_R

OR

B_L

AY

OU

T.V

2

GR

EA

T L

AK

ES

CO

UN

CIL

KA

RU

AH

RIV

ER

FL

OO

D S

TU

DY

A

B

C

D

EF

G

H

I

J

KL

M

N

O

P

QR

S

T

U

V

W

X

Y

Z

AA

BB

CC

DD

EE

FF

GG

HH

IIJJ

KK

LL

MM

NN

OO

PP

QQ

RR

SS

TT

UU

VVWWXX

YY

ZZ AAA

PP

Karuah River - Booral(209003)

(209008)Karuah River - Stroud Road

Karuah River - Dam Site

Karuah River - Monkerai

Mammy Johnsons River -Pikes Crossing

Mammy Johnsons River -Stroud Road

(209018)

(209001)

(209004)

(209002)

Legend

Catchment Boundary

Subcatchment Identifier

River Gauging Station

Subcatchment boundary

RORB Model junction

RORB storages

0 5 10

Scale (km)

FIGURE 5C0MPARISON - 1977 & 1978 FLOODS

28 March 2008DISC REF: 07012FILE REF: 07012_5_COMP_1977&1978 FLOODS_V3


0.0 50.0 100.0 150.0Duration (hours)

2000.0

1500.0

1000.0

500.0

0.0

Dis

char

ge(c

u.m

/s)

0.0 50.0 100.0 150.0Duration (hours)

2000.0

1500.0

1000.0

500.0

0.0

Dis

char

ge(c

u.m

/s)

Star

ttim

e:

Star

ttim

e:

Karuah River at Booral - March 197709

00hr

s,1

Mar

ch19

77

(Gauging Station 209003)(Gauging Station 209003)

Modelled

Recorded

Karuah River at Booral - March 1978

0000

hrs,

18M

arch

1978

Recorded

Modelled

FIGURE 6COMPARISON - 1990 FLOOD


8 APRIL 2008DISC REF: 07012FILE REF: 07012_6_COMP_1990 FLOODS_V3

0.0 50.0 100.0 150.0Duration (hours)

2000.0

1500.0

1000.0

500.0

0.0

Dis

char

ge(c

u.m

/s)

Star

ttim

e:

Karuah River at Booral - February 1990

0000

hrs,

2Fe

brua

ry19

90

Recorded

Modelled (RORB)

(Gauging Station 209003)

FIGURE 7COMPARISON (RORB Results) - 2001 FLOOD

8 APRIL 2008DISC REF: 07012FILE REF: 07012_7_COMP_2001 FLOOD_V3


0.0 50.0 100.0 150.0Duration (hours)

2000.0

1500.0

1000.0

500.0

0.0

Dis

char

ge(c

u.m

/s)

0.0 50.0 100.0 150.0Duration (hours)

2000.0

1500.0

1000.0

500.0

0.0

Dis

char

ge(c

u.m

/s)

Star

ttim

e:

Star

ttim

e:

Modelled (RORB)

Recorded

Karuah River at Dam Site #3 - May 200100

00hr

s,5

May

2001

Karuah River at Booral - May 2001

Recorded

Modelled (RORB)

0000

hrs,

5M

ay20

01

(Gauging Station 209003)(Gauging Station 209018)

FIGURE 8COMPARISON - 2007 FLOOD


10 September 2008DISC REF: 07012FILE REF: 07012_8_COMP_2007 FLOOD_V1

0.0 50.0 100.0 150.0Duration (hours)

2000.0

1500.0

1000.0

500.0

0.0

Dis

char

ge(c

u.m

/s)

Star

ttim

e:

Karuah River at Booral - June 2007

Recorded

0900

hrs,

7Ju

ne20

07

(Gauging Station 209003)

Modelled

FIGURE 9FLOOD FREQUENCY, KARUAH RIVER AT BOORAL


DISK REF: 07012FIG REF: 07012_9_FLOOD_FREQ_KARUAH_@BOORAL_V5

7 JUNE 2008

4000.0

3000.0

2000.0

Dis

char

ge(c

u.m

/s)

5000.0

1000.0

100.0

10000.0

Recurrence Interval (years)

Annual Exceedence Probability (% AEP)

2 5 10 20 50 100 200

50 20 10 5 2 1 0.5

LP3 +5%co

nfiden

ce

LP3 -5% confidence

Log Pearson 3 distribution

RORB with design rainfall

LegendHistorical Floods

GEV distribution(No areal reduction)

Adopted RORB with design rainfall(0.9 areal reduction factor)

FIGURE 10TRIBUTARY INFLOWS - 1% AEP STORM, 36 HOUR DURATION

15 AUGUST 2008DISC REF: 07012FILE REF: 07012_10_TRIB INFLOWS_1%AEP,36HR_V3


0.0 50.0 100.0Duration (hours)

2000.0

1500.0

1000.0

500.0

0.0

Dis

char

ge(c

u.m

/s)


2000.0

1500.0

1000.0

500.0

0.0

Dis

char

ge(c

u.m

/s)


2000.0

1500.0

1000.0

500.0

0.0

Dis

char

ge(c

u.m

/s)

Mammy Johnsons River @ Stroud Road

Karuah River @ Stroud Road

Ram Station Creek

Mill & Lamans Creeks

The Branch

Limeburners CreekCasey's Creek

Alderley Creek

Note: Hydrographs produced from calibrated RORB catchment model

FIGURE 11KARUAH RIVER FLOWS - 1%AEP STORM, 36 HR DURATION


DISK REF: 07012FIG REF: 07012_11_FLOWS_1%AEP, 36HR_V3

22 AUGUST 2008


4000.0

3000.0

2000.0

1000.0

0.0

Dis

char

ge(c

u.m

/s)

5000.0

Karuah River at Booral

Karuah at Old Pacific Highway, Karuah

Note: Hydrographs produced from calibrated RORB catchment model

FIGURE 12KARUAH RIVER - COMPARISON 1% AEP TO PMF

22 AUGUST 2008DISC REF: 07012FILE REF: 07012_12_PMFVS1%AEP_V3



0.0

Dis

char

ge(c

u.m

/s)



0.0

Dis

char

ge(c

u.m

/s)

Karuah at Old Pacific Highway, Karuah

PMF 24 hour

PMF 24 hour

Design 1% AEP

Design 1% AEP

15000

10000

5000

15000

10000

5000

0 5

Scale (Km)

GREAT LAKES COUNCIL

FIGURE 13LOCATION OF CROSS-SECTIONS - UPPER

28 OCTOBER 2008DISC REF: 07012FILE REF: 07012_13_LOCATION CROSS-SECTIONS - UPPER_V3


Legend

LocationCross-sectionFlood Level (resident interview, see Table 10)

Karuah River at BooralStation: 209003

Stroud Road

Stroud

Booral

To Gloucester

ToD

ungo g

Karuah River at Stroud Road

Karuah River at North Coast Railway

Karuah River at Washpool

Karuah River at Stroud Karuah River at Booral

Karuah River at Stroud

Karuah River

Mammy Johnsons River

Mill Creek

Karuah River

Alderley Creek

Boora l Creek

Ram

Stat

ion

Ck

K1

K2 K

3K

4

K4.

5

K5

K6 K

7 K8

K9

K10

K11

K12

K13

K14

K15

K16 K

17

K18

K19

K11#1

#1 #2

#3 #4#5

#6

#7

0 5

Scale (Km)

GREAT LAKES COUNCIL

FIGURE 14LOCATION OF CROSS-SECTIONS - LOWER

28 OCTOBER 2008DISC REF: 07012FILE REF: 07012_14_LOCATION CROSS-SECTIONS_LOWER_V3


Legend

LocationCross-sectionFlood Level (resident interview, see Table 10)

Allworth

Pacific Highway

Karuah By-passTo

Taree

To Raymond Terrace

Karuah River at Karuah By-pass

Karuah River at Pacific Highway


Karuah River

The Branch

Limeb

urner

sCre

ek

Booral C reek

K18

K19

K20 K

21

K22 K23

K24

K25

K26

K27 K28

K17

K18

K11#1

#8

8 May 2008DISK REF: 07012FILE REF: 07012_15_MIKE-11_LAYOUT_V2

FIGURE 15MIKE-11 MODEL LAYOUT


Mam

my

John

sons

R

Kar

uah

Riv

er

Ram

Stat

ion

Cre

ek

Mill

&L

ahm

anC

reek

Ald

erle

yC

reek

Cas

eyC

reek

The

Bra

nch

Lim

ebur

ners

Cre

ek

Kar

uah

Riv

er,P

ortS

teph

ens

Rai

lway

Bri

dge,

Stro

udR

oad

Low

leve

lbri

dge,

Stro

udR

oad

RT

AB

ridg

e,D

ungo

g-

Stro

udR

oad

HD

WB

#1pe

akle

vel

Boa

tRam

p,A

llwor

th

Kar

uah

By-

pass

Pac

ific

Hig

hway

,Kar

uah

2026

.0

4702

.058

85.1

1397

3.0

1851

2.0

2011

9.0

3654

8.0

4123

7.0

3353

.O

3655

.0

5918

.0

5956

.1

1241

4.0

1247

8.0

1770

2.0

2190

1.9

2194

8.0

2551

2.0

3154

2.0

4336

4.0

4701

3.0

Low

leve

lbri

dge,

Stro

ud

HD

WB

#2pe

akle

vel

HD

WB

#3pe

akle

vel

HD

WB

#4pe

akle

vel

HD

WB

#5pe

akle

vel

RT

AB

ridg

e,B

oora

l&D

EC

Cga

uge

"Karuah"

3634

.0

3717

.0

0.0

120.

0

"Karuah"

"Stroud_rail"

Rai

lway

Bri

dge

Bri

dge

Stru

ctur

eR

ailE

mba

nk.

5928

.0

5986

.0

0.0

120.

0

"Karuah"

"Washpool_br"

RT

AB

ridg

eB

ridg

eSt

ruct

ure

App

roac

hes

Wei

rSt

ruct

ure

3634

.0

3717

.0

0.0

120.

0

"Karuah"

"Booral_br"

App

roac

hes

Wei

rStr

uctu

re

0.0

40.0

"Booral_1"

0.0

40.0

"Booral_2"

Wei

rSt

ruct

ure

RTA bridgeBridge Structure

Bridge Structure

Approach BridgeBridge Structure

Approach Bridge

See Detail

See Detail

See Detail

3449

.0

3809

.0

Cat

tle

U'p

ass

App

roac

hSp

ans

Cul

vert

Stru

ctur

e

Cul

vert

Stru

ctur

e

5473

.0

0.0

393.

0 0.0

490.

062

24.0

"Stroud_rail_ubridge""Washpool_upass"

FIGURE 16HISTORICAL WATER LEVELS, PORT STEPHENS_SHEET 1

16 September 2009DISC REF: 07012FILE REF: 07012_16_HISTORICAL_WATER_LEVELS_SHT1_V3


0.0 50.0 100.0 150.0Duration (hours)

+1.0

0.0

-1.0

Wat

erle

vel(

mA

HD

)

0.0 50.0 100.0 150.0Duration (hours)

Star

ttim

e:

Star

ttim

e:

Tailwater Level, Port Stephens - March 197709

00hr

s,1

Mar

ch19

77

Tailwater Level, Port Stephens - March 1978

0000

hrs,

18M

arch

1978

0.0 50.0 100.0 150.0Duration (hours)

0.0 50.0 100.0 150.0Duration (hours)

Star

ttim

e:00

00hr

s,02

Feb

ruar

y19

90

Star

ttim

e:00

00hr

s,05

May

2001

+1.0

0.0

-1.0

Wat

erle

vel(

mA

HD

)

+1.0

0.0

-1.0

Wat

erle

vel(

mA

HD

)

+1.0

0.0

-1.0

Wat

erle

vel(

mA

HD

)

Tailwater Level, Port Stephens - February 1990 Tailwater Level, Port Stephens - May 2001

FIGURE 17


16 September 2009DISC REF: 07012FILE REF: 07012_17_HISTORICAL_WATER_LEVELS, PORT STEPHENS_SHT2_V3

HISTORICAL WATER LEVELS, PORT STEPHENS_SHEET 2

0.0 50.0 100.0 150.0Duration (hours)

Star

ttim

e:00

00hr

s,07

June

2007

+1.0

0.0

-1.0

Wat

erle

vel(

mA

HD

)

Tailwater Level, Port Stephens - June 2007

Flow (cu m/sec)

0.0

15.0

Rating Curve

1990 Modelled Flood

FIGURE 18COMPARISON MODEL RESULTS vs BOORAL RATING CURVE


DISK REF: 07012FIG REF: 07012_18_BOORAL QvsH_1990_V3

26 October 2009

Hei

ght(

mA

HD

)

5.0

10.0

(excludes overbank flows)(Based on DWE curveand actual gaugings)

50001000 2000 3000 4000

26 OCTOBER 2009DISK REF: 07012FILE REF: 07012_19_HISTORICAL_FLOOD_PROF_KARUAH_RIVER - UPPER_V5

FIGURE 19HISTORICAL FLOOD PROFILES - KARUAH RIVER - UPPER


2007 Flood1978 Flood

Design 1% AEP Flood

LEGEND

2007 Flood Mark1978 Flood Mark

1977 Flood

1977 Flood Mark

Flood Marks from StructuresBridge Structures

Bri

dge

-St

roud

Roa

d

Con

fluen

ce,R

amst

atio

nC

reek

Stro

udB

ridg

e

Con

fluen

ce,A

lder

ley

Cre

ek

Boo

ralB

ridg

e

Con

fluen

ce,B

oora

lCre

ek

HD

WB

#4

Con

fluen

ce,M

illC

reek

HD

WB

#2

HD

WB

#3

Hei

ght(

mA

HD

)

5 2520

Distance (kilometres)

0 10 15

Rai

lBri

dge,

Stro

udR

oad

Con

flue

nce,

Mam

my

John

sons

Riv

er

HD

WB

#1W

ashp

oolB

ridg

e

HD

WB

#5

0

10

20

30

40

50

60

-10

K1

K2

K3

K4

K4.

5

K6

K7

K8

K5

K9

K10

K11

K12

K13

K14

K16

K17

K18

K15

K19

26 OCTOBER 2009DISK REF: 07012FILE REF: 07012_20_HIST_FLOOD_PROFILES,KARUAH_ RIVER_ LOWER_V5

FIGURE 20HISTORICAL FLOOD PROFILES - KARUAH RIVER - LOWER

Hei

ght(

mA

HD

)


30 40 45Distance (kilometres)

25 35 50

2007 Flood1978 Flood

Design 1% AEP Flood

LEGEND

2007 Flood Mark1978 Flood Mark

1977 Flood

1977 Flood Mark

Flood Marks from StructuresH

DW

B#5

Boa

tRam

p,A

llwor

th

Allw

orth

-U

pstr

eam

Con

fluen

ce,L

imeb

urne

rsC

reek

Kar

uah

By-

Pass

Kar

uah

Bri

dge,

Paci

ficH

ighw

ay

Con

fluen

ce,T

heB

ranc

h

HD

WB

#6

0

5

10

15

20

25

30

-10

K19

K20

K21

K22

K23

K24

K25

K26

K27

K28

1987

1977

1977 1977

1990

20012007

FIGURE 21COMPARISON OF FLOOD LEVELS, KARUAH RIVER @ BOORAL


DISK REF: 07012FIG REF: 07012_21_COMPARISON OF LEVELS, KARUAH AT BOORAL_V3

26 OCT 2009

1971

19852007

1990

1978

2001

1976

1894

1978

1976

Gauge zero

"Cease to Flow" level

Top of Bank

Bed Level

Legend

DECC records

HDWB records

RTA Bridge Details

Bed Levels

Floo

dL

evel

(mA

HD

)

1978

Calculated flood levels

Stat

ion

2090

03DE

CC

reco

rd,

Stn

2090

03

RT

AB

ridg

e

"Kar

uah

Riv

er@

Boo

ral"

HD

WB

peak

leve

lind

icat

ors

RO

RB

/MIK

E-1

1ca

lcul

ated

leve

ls@

Boo

ralC

reek

0.0

5.0

10.0

15.0

20.0

Deck

Abut. top

Notes: This diagram indicates the flood levels at Booralas retrieved from three historical sources.

FIGURE 22DESIGN TAILWATER LEVELS , KARUAH


FIG REF: 07012_22_DESIGN_TAILWATER, KARUAH_V2DISK REF: 0701226 OCT 2009

Wat

erL

evel

(mA

HD

)

Design Tailwater , River Flooding plus Climate Change

0.0

3.00

2.00

1.00

0.00

-1.00

10.0 20.0 30.0 40.0 50.0 60.0

Time (hrs)

Design Tailwater , Port Stephens at Karuah

Design Tailwater , Current Ocean Flooding

Design Tailwater , Current River Flooding

26 October 2009DISK REF: 07012FILE REF: 07012_23_DESIGN_FLOOD_PROF_KARUAH_RIVER - UPPER_V5

FIGURE 23DESIGN FLOOD PROFILES - KARUAH RIVER - UPPER


2% AEP Flood1% AEP Flood

5% AEP Flood

LEGEND

PMF Flood


50% AEP Flood

Bridge Structures

0.5% AEP Flood

Bri

dge

-Str

oud

Roa

d

Con

fluen

ce,R

amst

atio

nC

reek

Stro

udB

ridg

e

Con

fluen

ce,A

lder

ley

Cre

ek

Boo

ralB

ridg

e

Con

fluen

ce,B

oora

lCre

ek

HD

WB

#4

Con

fluen

ce,M

illC

reek

HD

WB

#2

HD

WB

#3

Hei

ght(

mA

HD

)

5 2520


0 10 15

Rai

lBri

dge,

Stro

udR

oad

Con

flue

nce,

Mam

my

John

sons

Riv

er

HD

WB

#1W

ashp

oolB

ridg

e

HD

WB

#5

0

10

20

30

40

50

60

-10

K1

K2

K3

K4

K4.

5

K6

K7

K8

K5

K9

K10

K11

K12

K13

K14

K16

K17

K18

K15

K19

18 January 2010DISK REF: 07012FILE REF: 07012_24_DESIGN_FLOOD_PROFILES, KARUAH_ RIVER- LOWER_V5

FIGURE 24DESIGN FLOOD PROFILES - KARUAH RIVER - LOWER

Hei

ght(

mA

HD

)


30 40 45

Distance (kilometres)25 35 50


5% AEP Flood

LEGENDPMF Flood


50% AEP Flood

Bridge Structures

0.5% AEP Flood

HD

WB

#5

Boa

tR

amp,

Allw

orth

Allw

orth

-Ups

trea

m

Con

fluen

ce,L

imeb

urne

rsC

reek

Kar

uah

By-

Pass

Kar

uah

Bri

dge,

Paci

ficH

ighw

ay

Con

fluen

ce,T

heB

ranc

h

HD

WB

#6

0

10

15

20

25

30

-10

5

Flood levels affectedby Port Stephens (2% AEP and bigger)

K19

K20

K21

K22

K23

K24

K25

K26

K27

K28

19 Jan 2010DISK REF: 07012FILE REF: 07012_25_DESIGN_FLOOD_PROFILES, KARUAH_ RIVER_NEAR_KARUAH_V3

FIGURE 25DESIGN FLOOD PROFILES - KARUAH RIVER NEAR KARUAH

Hei

ght(

mA

HD

)



25 35


5% AEP Flood

LEGENDPMF Flood


50% AEP Flood

Bridge Structures

0.5% AEP Flood

HD

WB

#5

Boa

tRam

p,A

llwor

th

Allw

orth

-U

pstr

eam

Con

fluen

ce,L

imeb

urne

rsC

reek

Kar

uah

By-

Pass

Kar

uah

Bri

dge,

Paci

ficH

ighw

ay

Con

fluen

ce,T

heB

ranc

h

HD

WB

#6

0

2.0

3.0

4.0

5.0

1.0

Flood levels affectedby Port Stephens (50% AEP and bigger)

K19

K20

K21

K22

K23

K24

K25

K26

K27

K28

26 October 2009DISK REF: 07012FILE REF: 07012_26_SENSITIVITY_TESTING_KARUAH_RIVER - UPPER_V3

FIGURE 26SENSITIVITY TESTING - KARUAH RIVER - UPPER


1% AEP plus greenhouse

1% AEP Discharge factored by 1.2

LEGEND

1% AEP at peak of tide

1% AEP Friction factored by 1.2

Bridge Structures

1%AEP at trough of tide

Bri

dge

-Str

oud

Roa

d

Con

fluen

ce,R

amst

atio

nC

reek

Stro

udB

ridg

e

Con

fluen

ce,A

lder

ley

Cre

ek

Boo

ralB

ridg

e

Con

fluen

ce,B

oora

lCre

ek

HD

WB

#4

Con

fluen

ce,M

illC

reek

HD

WB

#2

HD

WB

#3

Hei

ght(

mA

HD

)

5 2520


0 10 15

Rai

lBri

dge,

Stro

udR

oad

Con

flue

nce,

Mam

my

John

sons

Riv

er

HD

WB

#1W

ashp

oolB

ridg

e

HD

WB

#5

0

10

20

30

40

50

60

-10

K1

K2

K3

K4

K4.

5

K6

K7

K8

K5

K9

K10

K11

K12

K13

K14

K16

K17

K18

K15

K19

21 January 2010DISK REF: 07012FILE REF: 07012_27_SENSITIVITY PROFILES,KARUAH_ RIVER_ LOWER_V4

FIGURE 27SENSITIVITY TESTING - KARUAH RIVER - LOWER

Hei

ght(

mA

HD

)



25 35 50

1% AEP plus greenhouse1% AEP Discharge factored by 1.2

LEGEND1% AEP at peak of tide

1% AEP Friction factored by 1.2

Bridge Structures

1%AEP at trough of tide

Port Stephens with 0.92 increasePort Stephens withtide, storm surge, wind set-up

HD

WB

#5

Boa

tRam

p,A

llwor

th

Allw

orth

-U

pstr

eam

Con

fluen

ce,L

imeb

urne

rsC

reek

Kar

uah

By-

Pass

Kar

uah

Bri

dge,

Paci

ficH

ighw

ay

Con

fluen

ce,T

heB

ranc

h

HD

WB

#6

0

10

12.5

-2.5

5

K19

K20

K21

K22

K23

K24

K25

K26

K27

K28

FIGURE 28DIAGRAMMATIC REPRESENTATION, FLOOD LEVELS


DISK REF: 07012FIG REF: 07012_28_DIAGRAM_FLOOD_LEVELS_V2

26 October 2009

Mean Sea Level ( 0.0 m AHD)

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)

2007 flood level (RL 23.02 m AHD)

Highest flood, resident report (RL 26.63 m AHD)

Bed (approx RL 16.6 m AHD)

Typical flood levels, Karuah River near Stroud

GREAT LAKES COUNCIL

FIGURE 29PROVISIONAL FLOOD HAZARD 5% AEP - SHEET 1

10 FEB 2010DISC REF: 07012FILE REF: 07012_29_PROV_ HAZARD_5%AEP_SH1_V2


Area not flooded by Karuah River

Floodway - Low Hazard

Floodway - Medium Hazard

Floodway - High Hazard

Flood storage - High Hazard

Flood storage - Low Hazard

Flood storage - Medium Hazard

Legend

0 51 2 3 4

Stroud Road

Stroud




Flood liability extends towards StroudFor detail, see Stroud Flood Study

Karuah River at RTA bridge "Washpool"

Kilometres

To Gloucester

To

Dungog

FL

40. 0FL 41.0

FL 39.0

FL38.0

FL

3 7.0

FL36.0

FL35.0

FL34.0

FL 33.0

FL 32.0

FL 31.0

FL

30.0

FL

29.0

FL28.0

FL27.0

FL

26.0

FL25.0

FL

24.0

FL

2 3.0

FL 22.0

FL 21.0

FL

20.0

FL19.0


Mill Creek Karuah River

Alderley Creek

Ram

Stat

ion

Ck

Karuah River

Karuah River

GREAT LAKES COUNCIL


16 FEB 2010DISC REF: 07012FILE REF: 07012_30_PROV. HAZARD_5%AEP_SHT 2_V2


0 51 2 3 4








Legend

FL

18.0

FL17

.0

FL

16.0

FL

1 5. 0

FL14

.0 FL 13.0

FL 12.0

FL11.0

FL 10.0

FL

9.0

FL8.0

FL7.

0

FL6.

0 FL5.0

FL4.

0

Kilometres


BooralT

oB

uled

e lah

To Stroud

To Pacific Highway

Allworth


FL

19.0

Karuah River

Alderley Creek

Boor al C

r ee k

Karuah River

K aru

ahRi

ver

Karua

h River

GREAT LAKES COUNCIL


16 FEB 2010DISC REF: 07012FILE REF: 07012_31_PROV. HAZARD_5%AEP_SHT 3_V2


Karuah RiverKaruah River

Karuah River

The

Branc h

Th eB

ranch








Legend

0 51 2 3 4

FL

3.5

FL

3.0

FL2.5

FL2.0

FL

1.7 6

Kilometres

Allworth

Pacific Highway

Ka r

u ah

By-

p ass

To

Tar

ee

To Raymond

Terrace

GREAT LAKES COUNCIL


5 FEB 2010DISC REF: 07012FILE REF: 07012_32_PROV. HAZARD_1%AEP_SH1_V2









Legend

Kilometres

0 51 2 3 4

FL42.0

FL41.0

FL40

.0

FL39.0 FL 38. 0

FL37 .0

FL36.0

FL35.0

FL34.0

FL33.0

FL32.0

FL

31.0 FL3

0.0

FL

29.0

FL

28.0

FL2

7.0

FL26.0

FL25.0

FL 2

4.0

FL23.0F

L22 . 0

FL21.0

Stroud Road

Stroud

To Gloucester

To

Dungog








Alderley Creek

Ram

Stat

ion

Ck

Karuah River

Karuah River

GREAT LAKES COUNCIL











Legend

Kilometres

0 51 2 3 4

FL

21.0

FL2

0.0

FL1

9.0

FL 1

8.0

FL17

.0F

L16.

0

FL15

.0

FL14.0

FL12.0

FL1

1.0

FL13.0

FL 1

0 .0

FL9.0

FL8

.0

FL7.

0

FL6.0

FL5.

0


BooralT

oB

uled

e lah

To Stroud

To Pacific Highway

Allworth


Karuah River

Alderley Creek

Booral Creek

Karuah River

K aru

ahRi

ver

Karuah

River

GREAT LAKES COUNCIL





Karuah River

The

Branc h

Th eB

ranch

0 51 2 3 4

Kilometres








Legend

FL4.0

FL3

.5

FL3.0

FL2.5

FL2.0

FL1.91

Allworth

Pacific Highway

Ka r

u ah

By-

p ass

To

Tar

ee

To Raymond

Terrace

GREAT LAKES COUNCIL

FIGURE 35PROVISIONAL FLOOD HAZARD 0.5% AEP - SHEET 1

10 FEB 2010DISC REF: 07012FILE REF: 07012_35_PROV. HAZARD_0.5%_SH1_V2









Legend

Kilometres

0 51 2 3 4

Stroud Road

Stroud

To Gloucester

To

Dungog





FL43.0

FL42.0

FL41.0 FL40.0

FL39

.0

FL 38.0

FL3 7.0

FL35.0

FL34.0

FL33.0

FL32.0

FL31.0FL30.0

FL29.0

FL28.0

FL36.0

FL27.0FL26.0 F

L25.

0

FL2

4.0

FL23.0

FL22.0

FL21.0



Mill Creek

Karuah River

Alderley Creek

Ram

Stat

ion

Ck

Karuah River

Karuah River

GREAT LAKES COUNCIL


10 FEB 2010DISC REF: 07012FILE REF: 07012_36_PROV. HAZARD_0.5%AEP_SH2_V2


0 51 2 3 4








Legend

Kilometres

5.00


BooralT

oB

uled

e lah

To Stroud

To Pacific Highway

Allworth


FL1

8.0

FL1

9.0

FL

2 0.0

FL

21.0

FL17

.0F

L16

. 0

FL1

5.0

FL1

4.0

FL

1 3.0

FL1

2.0

FL1

1.0

FL9.0

FL8.

0

FL6.0

FL 5

. 0

FL7.0

FL10.0

Karuah River

Alderley Creek

Booral Creek

Karuah River

K aru

ahRi

ver

Karua

h River

GREAT LAKES COUNCIL


12 FEB 2010DISC REF: 07012FILE REF: 07012_37_PROV. HAZARD_0.5%AEP_SH3_V2



Karuah River

The

Branc h

Th eB

ranch








Legend

0 51 2 3 4

Kilometres

FL4

.5

FL4.0

FL3.5

FL

2.0 F

L1.

98

FL

3.0

FL2.5

FL

5.0

Allworth

Pacific Highway

Ka r

u ah

By-

p ass

To

Tar

ee

To Raymond

Terrace

GREAT LAKES COUNCIL

FIGURE 38PROVISIONAL FLOOD HAZARD PMF - SHEET 1

12 FEB 2010DISC REF: 07012FILE REF: 07012_38_PROV. HAZARD_PMF_SH1_V2









Legend

Kilometres

0 51 2 3 4

Stroud Road

Stroud

To Gloucester

To

Dungog





FL46.0

FL45.0

FL44.

0F

L42

.0

FL41

.0

FL

40.0

FL3

9.0

FL38. 0

FL37.0

FL36.0

FL3

5.0

FL

34.0

FL

33.0

FL3

2.0


FL47.0



Alderley Creek

Ram

Stat

ion

Ck

Karuah River

Karuah River

FL3 1

.0

FL 4

3.0

FL30

.0

FL

29.0

FL

28.0

GREAT LAKES COUNCIL











Legend

Kilometres

0 51 2 3 4


BooralT

oB

uled

e lah

To Stroud

To Pacific Highway

Allworth


Karuah River

Alderley Creek

Booral Creek

Karuah River

K aru

ahRi

ver

Karua

h River

FL2

8.0

FL 1

9.0

F L20

. 0

FL 2

1 .0

FL2

2.0

FL2

3.0

FL

24.0

FL 2

5 .0

FL2

6.0

FL

27.0

FL18

.0

FL1

7.0

FL16.0

FL1

5.0

FL1

4 .0

FL13

.0

FL12.0FL11.0

FL

10.0

GREAT LAKES COUNCIL





Karuah River

The

Branc h

Th eB

ranch








Legend

Kilometres

0 51 2 3 4

Allworth

Pacific Highway

Ka r

u ah

By-

p ass

To

Tar

ee

To Raymond

Terrace

FL 8

.5

FL9

.0 FL8.0FL7.5

FL7.0

FL6.5

FL6.0

FL5.5

FL5.0 FL4.5

FL4.0

FL3.5

FL3.0F

L2.5FL2.0




APPENDICES




APPENDIX A

ANNUAL FLOOD SERIES, STATION 209003 “KARUAH RIVER AT BOORAL”


Great Lakes CouncilAppendix A Karuah River Flood StudyPage A1 Final Report - November 2010

R90 \07012.V8

APPENDIX A

Annual Flood Series, Station 209003 “Karuah River at Booral”

Recorded Yearly Peak – Karuah River at Booral

Peak Flow Peak HeightDate 1

Q (ML/day) Q (cu m/sec) G H (m) m AHD

AnnualRank

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 CouncilKaruah River Flood Study Appendix AFinal Report - November 2010 Page A2R90\07012.V8

Peak Flow Peak HeightDate 1

Q (ML/day) Q (cu m/sec) G H (m) m AHD

AnnualRank

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 years of record, from 1969 to 2007 inclusive. 2007 has been included because it wassignificant, despite the year not being complete

2. Records indicate a peak annual GH of 6.71 m at 9 am on 24/06/1972 but this was exceededin January 1972 as listed above

3. Flows for these flood events (in Ml/day) were read by Paterson Consultants from ratingtables. All other flows were supplied by DWE.




APPENDIX B

DAILY RAINFALL STATIONS AND PLUVIOMETER STATIONS


Great Lakes CouncilKaruah River Flood Study Appendix BFinal Report - November 2010 Page B1R90\07012.V8

APPENDIX B-1DAILY 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




-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



APPENDIX B-2PLUVIOMETER STATIONS


-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




APPENDIX C

DESIGN RAINFALLS – INTENSITY-FREQUENCY-DURATION

*** 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 69.411.25 21.79 28.13 36.19 41.02 47.44 55.99 62.611.5 19.64 25.4 32.88 37.37 43.33 51.29 57.472 16.63 21.59 28.2 32.21 37.5 44.6 50.123 13.13 17.12 22.66 26.06 30.52 36.53 41.254 11.09 14.52 19.39 22.41 26.35 31.69 35.95 9.73 12.77 17.18 19.93 23.51 28.39 32.236 8.74 11.5 15.56 18.12 21.43 25.94 29.518 7.39 9.76 13.32 15.59 18.51 22.52 25.710 6.49 8.59 11.81 13.87 16.53 20.18 23.0912 5.83 7.74 10.71 12.61 15.07 18.45 21.1514 5.39 7.15 9.85 11.58 13.81 16.88 19.3316 5.04 6.67 9.16 10.76 12.81 15.63 17.8818 4.75 6.27 8.6 10.07 11.98 14.6 16.6820 4.5 5.94 8.11 9.5 11.28 13.73 15.6822 4.28 5.65 7.7 9 10.68 12.99 14.8124 4.09 5.39 7.34 8.57 10.16 12.34 14.0636 3.3 4.33 5.84 6.78 8 9.67 10.9848 2.81 3.68 4.92 5.7 6.7 8.06 9.1460 2.47 3.23 4.29 4.94 5.8 6.96 7.8772 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 73.661.25 21.66 28.11 36.81 42.03 48.86 57.94 64.971.5 19.51 25.33 33.16 37.86 44.02 52.21 58.542 16.51 21.43 28.07 32.05 37.27 44.2 49.573 13.01 16.89 22.13 25.27 29.39 34.87 39.14 10.98 14.26 18.68 21.34 24.81 29.44 33.025 9.63 12.5 16.38 18.71 21.76 25.82 28.966 8.65 11.23 14.72 16.81 19.55 23.2 26.028 7.3 9.48 12.43 14.2 16.52 19.6 21.9910 6.41 8.32 10.91 12.46 14.5 17.21 19.312 5.76 7.47 9.8 11.2 13.03 15.47 17.3514 5.25 6.82 8.97 10.26 11.95 14.2 15.9416 4.84 6.3 8.3 9.51 11.08 13.19 14.8218 4.51 5.87 7.75 8.88 10.37 12.35 13.8820 4.23 5.51 7.28 8.36 9.77 11.64 13.122 3.99 5.2 6.89 7.91 9.25 11.03 12.4224 3.78 4.93 6.54 7.52 8.8 10.5 11.8336 2.93 3.83 5.12 5.91 6.93 8.31 9.3848 2.42 3.17 4.27 4.94 5.81 6.98 7.8960 2.08 2.72 3.68 4.27 5.03 6.06 6.8672 1.82 2.39 3.24 3.77 4.45 5.36 6.08________________________________________________________________




APPENDIX D

DESIGN FLOOD LEVELS

Paterson Consultants Pty Ltd

APPENDIX D Great Lakes CouncilPage D1 Karuah River Flood Study


APPENDIX D

DESIGN FLOOD LEVELS

Design Peak Flood Levels (m AHD)(36 hour storm, flood peak co-incident with peak tide)Model Calculation

PointsLocation River

SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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,Stroud Road

3353.0

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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, MammyJohnsons Creek

4702.4

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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,Ramstation Creek

5885.1

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 RTAbridge, "Washpool"

5956.1

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

Stroud


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, MillCreek

13973.3

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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


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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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, AlderleyCreek

18512.6

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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,Booral

21901.9

KARUAH 21911.00 7.01 8.38 9.15 10.36 10.61 11.39 12.16 17.96


KARUAH 22135.46 6.50 7.97 8.79 10.58 10.94 11.47 12.24 17.88






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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, BooralCreek

23169.9

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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


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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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,Allworth

31542.4

KARUAH 31637.75 1.59 2.23 2.68 3.65 3.98 4.54 5.08 9.53


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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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, TheBranch

36548.2

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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






SectionRiver

Distance(m) 50%

AEP20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP PMP

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 E

DESIGN FLOOD FLOWS


APPENDIX E Great Lakes CouncilPage E1 Karuah River Flood Study


APPENDIX E

DESIGN FLOOD DISCHARGES

Design Peak Flood Flows (cu m/sec)(36 hour storm, flood peak co-incident with peak tide)Model Calculation Points Location River

SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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, StroudRoad

3,353.0

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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, MammyJohnsons Creek

4,702.4

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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, RamstationCreek

5,885.1

KARUAH 5921.74 631 1080 1389 1970 2314 2755 3217 7834

KARUAH 5956.00 High Level RTA bridge,"Washpool"

5,956.1 0 0 0 0 0 0 0 158

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

KARUAH 17270.31 729 1242 1610 2424 2691 3211 3745 9189


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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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






SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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


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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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


KARUAH 31760.90 849 1369 1743 2764 2948 3536 4135 10614





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

KARUAH 41130.90 1390 1922 2324 3311 3630 4323 5064 13477

Confluence LimeburnersCreek

41,237.3

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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, PacificHighway

47,012.7

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





SectionRiver

Distance50%AEP

20%AEP

10%AEP

5%AEP

2%AEP

1%AEP

0.5%AEP

PMP

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_UBRIDGE 190.00

2 16 14 25 25 30 25 15




APPENDIX F

SENSITIVITY TESTING


APPENDIX F Great Lakes CouncilPage F1 Karuah River Flood Study


APPENDIX F

SENSITIVITY TESTING

Flood Level for Various Run Conditions(See Run Conditions at end of this Table)

(m AHD)Model Identification Location RiverSection

RiverDistance

(m) Run 1 Run 2 Run 3 Run 4 Run 5 Run 6

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, StroudRoad

3655.0






RiverDistance

(m) Run 1 Run 2 Run 3 Run 4 Run 5 Run 6KARUAH 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






RiverDistance

(m) Run 1 Run 2 Run 3 Run 4 Run 5 Run 6KARUAH 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


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






RiverDistance


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






RiverDistance


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


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






RiverDistance


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






RiverDistance


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


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






RiverDistance


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






RiverDistance

(m) Run 1 Run 2 Run 3 Run 4 Run 5 Run 6Bucketts Way bridge, Booral 21901.9

KARUAH 21911.00 11.39 11.39 11.39 9.15 12.32 12.30


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






RiverDistance


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


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






RiverDistance


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






RiverDistance


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


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






RiverDistance


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






RiverDistance


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






RiverDistance


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






RiverDistance


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






RiverDistance


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:




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.