Logan River Catchment Hydrological Study...and rainfall spatial distribution and design rainfall losses) adopted in the study are based on a comprehensive review of the latest available

1

Logan River Catchment

Hydrological Study

December 2014

Version 3 TRACKS-#45737331-v3-LOGAN_RIVER_HYDROLOGICAL_STUDY_DECEMBER_2014

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Title: Logan River Catchment Hydrological Study

Author:

Study for: City Planning Branch

Planning and Environment Directorate

The City of Gold Coast

File Reference: WF15/44/02 (P1)

TRACKS #45737331

Version history

Version Comments/Change Changed by

& date Reviewed by &

date

1.0 Draft

2.0 Review

3.0 Review

4.0 Peer Review

3.0 Review

4.0 Review

Distribution list

Name Title Directorate Branch


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1. Executive Summary

Overview

The main objective of the study is to develop a suite of hydrological models for the City of Gold Coast (City) that are based on one type of modelling software (URBS), calibrated and verified against available data, and fully documented to a consistent standard. The calibrated model is to be used to estimate design flood discharges for design events ranging from 2 years Average Recurrence Interval (ARI) to PMF.

The hydrological modelling of the Logan River catchment was undertaken using an approach and methodology consistent with the other catchments in the City area. For this study, the Logan River catchment has been developed as a single URBS model for the whole Logan River Catchment (consisting Upper Logan, Teviot Brook, Albert River and Lower Logan). The model parameters were kept global for the whole catchment, and the model configurations were kept as simple as possible. The URBS models have been configured based on current catchment land uses.

Model Calibration and Verification

Calibration data used in the Logan River Hydrology study 2009 (Ref. 2) were available for use in the current study. All the available data were sourced from BOM for a total of 26 flood events between 1947 and 2013. The available rainfall and stream flow data for early events are very limited and of poor quality. Therefore the selected calibration and verification events are generally the most recent events, with the exception of the January 1974 event, which is the largest on record. From the available data, five flood events (January 1974, April 1990, February 1991, January 2008 and January 2013) were selected for model calibration and a further four events (May 1980, April 1988, March 2004 and January 2012) were selected for model verification. The selected events cover a wide range of discharges across the whole Logan River catchment.

The emphasis of the model calibration was to achieve the best possible fit between the predicted and recorded discharge hydrographs at key stations along the main streams of the Logan River catchment for the selected calibration events. For these stations, the calibration attempted to match the predicted and recorded flood peaks and volumes, and also the shape of the hydrographs. The calibrated model was then verified by comparing the model predictions against the discharge hydrographs recorded at various gauging stations for the selected verification events.

Due to the lack of available rainfall data for most events and the lack of detailed rainfall data where data were available, the URBS model cannot be expected to accurately reproduce flood behaviour for all events and at all gauging stations. As such more calibration emphasis was placed on large events, as the accuracy of small events are impacted significantly by spatial and temporal variation in rainfall. A single set of model parameters were adopted for the model, and maintained for all calibration and verification events. The model parameters were adjusted to achieve the best calibration across all events, resulting in a compromise between model accuracy and model simplicity. It is noted that calibration of the model for gauging stations in different parts (Teviot Brook, Upper Logan, Albert River and Lower Logan) of the Logan River catchment can be improved by adopting different sets of model parameters for each part of the catchment. Further the calibration of the model for individual events can be improved by adopting a different set of model parameters for each of the different events. The adopted model parameters are given below:


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Parameter Adopted Value

(Channel Lag Parameter) 0.2

(Catchment Lag Parameter) 2.5

m (Catchment non-linearity Parameter) 0.75

F (Forest Factor) F*0.5

Rainfall losses were adjusted to achieve the best possible hydrograph shapes and flood volumes. A uniform initial loss and continuing loss rate were adopted for the model and each flood event. It is noted that calibration of the models for individual events can be improved by adopting a set of variable loss rates within the catchment for each of the different events.

Calibration Results

Satisfactory calibration was achieved throughout the catchment, with the URBS models generally reproducing recorded flood discharges adequately.

The model calibration for Teviot Brook is generally good, considering that a single set of global model parameters were adopted across all nine historical events. The model calibration results for large events are excellent; however the model results for smaller events show the predicted flood peak arriving earlier than the recorded peak. This issue could be addressed, if necessary, by adopting different model parameters including initial and continuing losses for smaller events.

The model calibration at the Broomfleet and Wolffdene is generally good even though some inconsistencies between recorded peak discharges at Bromfleet and Wolffdene are evident. The model predicted excellent result at Broomfleet and Wolffdene, however results show early peak for smaller events.

The model calibration for the Upper Logan catchment is generally excellent. Although calibration for the large events (January 1974, April 1990 and February 1991) was generally quite good at both Yarrahappini and Round Mountain gauging stations, the model predicted a lower peak at Round Mountain and a slightly higher peak at Yarrahappini for smaller events (January 2008 and January 2013).

The quality of available data (both rainfall and stream flow) for the Lower Logan catchment is not as good as for the upstream of the catchment. For the January 1974, May 1980 and April 1990 flood events, the complete water level hydrographs were not recorded at the Macleans Bridge and Waterford gauges (the recorded water level hydrograph at Waterford for the January 1974 flood has been synthesised based on debris marks at the gauge site). Complete recorded water level hydrographs at both stations were available for the April 1988, February 1991, January 2008, January 2012 and January 2013 events. The two gauging stations with available data (Macleans Bridge and Waterford) are BOM flood forecasting stations, not Department of Natural Resources and Mines (DNRM) stations, and as such the quality of rating curves for these two stations is uncertain. The rating curve for Macleans Bridge appears to be acceptable; however the Waterford rating is poor, especially for higher discharges. As a result the calibration is generally good at Macleans Bridge, but somewhat poor at Waterford. The Waterford gauge is tidally affected, and may also be affected by downstream water levels (including Albert River outflows). The timing and shape of the predicted


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hydrographs at Waterford is generally acceptable but the predicted peak discharges are generally higher than recorded peak flows for the larger events. Predicted peak discharges at Macleans Bridge are generally good, indicating a problem with the Waterford rating curve. Further, the recorded flood volumes at Waterford appear to be less than those recorded at Macleans Bridge.

Design Flood Discharges

The calibrated URBS model was used to estimate design flood discharges throughout the Logan River catchment based on design rainfall intensity – frequency – duration (IFD) data from a number of sources. Design flood discharge hydrographs were estimated for a range of storm durations up to the 120 hour event for the 2, 5, 10, 20, 50, 100, 200, 500, 1000 and 2000 year ARI events, Probable Maximum Precipitation Design Flood (PMPDF) and PMF events. The design rainfall data and associated procedures and input data (including IFD data, temporal patterns, areal reduction factors, and rainfall spatial distribution and design rainfall losses) adopted in the study are based on a comprehensive review of the latest available data and information.

A comparison of the estimated peak design discharges from this study with the peak design discharges reported in three previous studies (WRM 2009 – Ref. 2, Sunwater 2007 – Ref. 5 and AWE 1997 – Ref. 4) was undertaken. A summary of findings with respect to the discharge estimates from the different studies is given below. Note that the AWE (1997) and WRM (2009) studies covered the whole Logan River catchment, whereas the Sunwater (2007) study was restricted to the Teviot Brook catchment.

The URBS model estimated peak design discharges for Teviot Brook at The Overflow match closely with the estimates given by the Sunwater (2007) and WRM (2009) studies for all ARIs up to, and including, the 2000 Year ARI event.

The URBS model estimated peak discharges at Bromfleet, Wolffdene and Beenleigh match the AWE (1997) estimated peak discharges reasonably; however the URSB model estimated peak discharges at these stations are higher than those estimated by the WRM (2009) study. This is likely due to differences in adopted design rainfalls and temporal patterns between the WRM (2009) and current studies. The adopted rating curve at Wolffdene also differs substantially between the current study and the AWE (1997) study. It is also noted that an additional model (forest factor) parameter and a single set of model parameters were used for the whole Logan catchment in this study.

The URBS model estimated peak discharges at Yarrahappini closely match the AWE (1997) estimated peak discharges, and are higher than the WRM (2009) study. The URBS model estimated discharges at Waterford are lower than those estimated by the AWE (1997) study. The calibration and verification events selected for this study indicated that significant attenuation of flows in the Logan River occurs between Yarrahappini and Waterford (WRM 2009, Ref. 2). The URBS model developed for this study was configured to reproduce this attenuation as best as possible. The AWE (1997) study was not calibrated at Waterford, and as such no such attenuation is evident in the results from that study. The AWE (1997) study did not apply ARFs to design rainfalls.

The current study calibrated the model to two additional recent flood events (January 2012 and January 2013) as compared WRM (2009) study. The study also used an additional model


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parameter (forest factor) as compared to the study of WRM (2009), as well as some modification of methodologies.

Flood Frequency Analysis

Flood frequency analyses (FFA) was undertaken using the methodology recommended in Australian Rainfall and Runoff (IEAust, 1987 – Ref. 11) by fitting a Log-Pearson Type III distribution to annual series of recorded peak flood discharges at the following key gauging stations within the catchment with more than 30 years of historical record:

Teviot Brook at The Overflow (DNRM GS 145012a)

Logan River at Round Mountain (DNRM GS 145008a)

Logan River at Yarrahappini (DNRM GS 145014a)

Albert River at Bromfleet (DNRM GS 145102b)

Albert River at Wolffdene (DNRM GS 145196a).

The URBS model estimated peak design discharges at the above stations were compared with the peak discharge estimates obtained from the FFA to assess the consistency between the two sets of discharge estimates and reconcile any differences between estimates from the two methods. The results were also compared with FFA results from the AWE (1997), SunWater (2007) and WRM (2009) studies. It is noted that AWE (1997) has undertaken FFA only for Logan River at Yarrahappini and Albert River at Bromfleet and Wolffdene; SunWater (2007) has undertaken FFA only for Teviot Brook at The Overflow. It is also noted that the AWE (1997) FFA are based on some 10 years less data than the analyses undertaken for this study, except at Yarrahappini where some historical anecdotal data have been used. The results of the comparisons are summarised below.

The design peak discharges estimated by the URBS model for Teviot Brook at The Overflow correspond well to the flood frequency discharge estimates for the 20 Year ARI up to the 100 Year ARI. For ARIs less than 20 Years, the URBS model discharge estimates are higher than those predicted by the FFA; however, the URBS model discharge estimates are well within the flood frequency confidence limits for the 5 and 10 Year ARIs. Further to this, the URBS model results match discharges predicted by the Sunwater (2007) Teviot Brook URBS model for all ARIs except for the 2 year ARI.

The design peak discharges estimated by the URBS model for the Logan River at Round Mountain are within the confidence limits for the flood frequency discharge estimates for all ARIs up to 100 Year ARI floods and matches reasonably well. However in general the URBS model discharges at Round Mountain are higher than the flood frequency discharges. This is a result of attempting to reconcile the URBS model discharges with the FFA estimates at Yarrahappini using a uniform catchment loss approach. The catchment area at Yarrahappini is almost double that at Round Mountain, and as such more emphasis was placed on reconciling the URBS model discharges with the FFA at Yarrahappini. As a result of this strategy, the URBS model appears to overestimates discharges at Round Mountain but gives acceptable (in some cases high) discharge estimates at Yarrahappini when compared with the FFA at these two locations.


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The design peak discharges estimated by the URBS model for the Logan River at Yarrahappini correspond reasonably well to the flood frequency discharge estimates for the 2, 5 and 100 Year ARI. For ARIs 10, 20 and 50 Years the URBS model discharge estimates are higher than those predicted by the FFA; however the URBS model discharge estimates are well within the flood frequency confidence limits. It is further noted that the URBS model predicted discharges match very well with discharges from AWE (1997) at Yarrahappini. The table below compares the URBS model estimated peak design discharges at Yarrahappini and Round Mountainn with the peak discharge estimates obtained from the FFA.

ARI (years)

Estimated Peak Design Discharge (m3/s)

Round Mountain Yarrahappini

FFA URBS FFA URBS

2 453 537 572 542

5 1083 1151 1092 1284

10 1560 1691 1580 2122

20 2023 2318 2212 2960

50 2606 2971 3369 3994

100 3018 3515 4579 4838

The design peak discharges estimated by the URBS model for the Albert River at Bromfleet correspond very well to the flood frequency discharge estimates for all ARIs up to the 100 Year flood. This is of some significance, as Bromfleet has the longest annual peak series (76 years of data), meaning that discharge estimates for up to and including the 50 Year ARI event are reasonably certain.

The design peak discharges estimated by the URBS model in the Albert River at Wolffdene correspond adequately to the FFA discharge estimates for the 50 and 100 Year ARI floods. The 2, 5, 10 and 20 Year ARI URBS model discharges are higher than the FFA estimates, but are still within the FFA confidence limits, except for the 2 year ARI.

Joint Probability Approach (JPA)

Monte Carlo simulations were undertaken using the Total Probability Theorem approach (TPT) and Cooperative Research Centre – Catchment Hydrology approach (CRC-CH). These techniques offered an alternative to the design event approach in estimating peak discharges for various ARI events. The results of the TPT techniques gave further support of the discharges obtained from the Design Event Approach. However, it was found that application of CRC-CH technique would require additional background work for it to be used with confidence for the Logan River catchment. The figure below shows a comparison of the design discharge estimates from the design event and the JPA approaches at Yarrahappini gauging station. Comparison of design discharges from design event and JPA approach at other gauging stations are shown in Section 10.


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Conclusion

A URBS model of the Logan River catchment has been satisfactorily calibrated and verified against available data, and then the calibrated model has been used to estimate design flood discharges at key locations in the catchment for design events ranging from 2 year ARI to PMF. In addition, the URBS model design discharge estimates have been reconciled with FFA estimates of design discharges at five key gauging stations within the catchment and verified using the JPA approach. The JPA supported the URBS model design discharge estimates. All analyses in this study have been undertaken using methodology consistent with the hydrologic modelling currently being undertaken for other catchments in the Gold Coast. The methodology and results of this study have been fully documented to a consistent standard.


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Table of Contents

1. Executive Summary ...................................................................................................................... 3

2. Introduction ................................................................................................................................. 13

2.1 Overview ............................................................................................................................ 13

2.2 Study Objectives and Scope .............................................................................................. 13

2.3 Limitation Statement .......................................................................................................... 14

2.4 Acknowledgement ............................................................................................................. 14

2.5 Previous Studies ................................................................................................................ 14

2.5.1 Logan and Albert Rivers Flood Plain Modelling Study (1997) (Ref. 4) ..................... 14

2.5.2 Wyaralong Dam, Design Flood Hydrology Report (2007) (Ref. 5) ........................... 14

2.5.3 Logan River Catchment Hydraulic Study (2007) (Ref. 6) ......................................... 15

2.5.4 Logan River Flood Study (2009) (Ref. 2) .................................................................. 15

2.5.5 Logan River Hydrological Study Addendum Report (2010) (Ref. 7) ......................... 15

3. Catchment Description ............................................................................................................... 16

3.1 Overview ............................................................................................................................ 16

3.1.1 Upper Logan Catchment .......................................................................................... 18

3.1.2 Lower Logan Catchment .......................................................................................... 18

3.1.3 Teviot Brook Catchment ........................................................................................... 19

3.1.4 Albert River Catchment ............................................................................................ 19

3.2 Land Use ........................................................................................................................... 20

3.3 Stream Gauging Stations ................................................................................................... 20

4. Methodology ................................................................................................................................ 22

4.1 Comprehensive Review of Existing Models and Data ....................................................... 22

4.2 Model Construction ............................................................................................................ 22

4.3 Model Calibration and Verification ..................................................................................... 22

4.4 Design Discharge Estimation ............................................................................................. 23

4.5 Joint Probability Approach/Monte Carlo Simulation ........................................................... 23

4.6 Preparation of Study Report .............................................................................................. 23

5. Available Data .............................................................................................................................. 24

5.1 Topographic Data .............................................................................................................. 24

5.2 Land Use Data ................................................................................................................... 24

5.3 Rainfall Data ...................................................................................................................... 24

5.3.1 Pluviograph Data ...................................................................................................... 24

5.3.2 Daily Data ................................................................................................................. 28

5.4 Streamflow Data ................................................................................................................ 32

5.5 Storage Data ...................................................................................................................... 36

5.5.1 Maroon Dam ............................................................................................................. 36

5.5.2 Bromelton Weir ......................................................................................................... 36

5.5.3 Cedar Grove Weir..................................................................................................... 37


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5.5.4 Wyaralong Dam ........................................................................................................ 37

5.6 Rating Curves .................................................................................................................... 39

5.6.1 Teviot Brook at The Overflow (DNRM GS 145012a) ................................................ 40

5.6.2 Logan River at Round Mountain (DNRM GS 145008a) ........................................... 40

5.6.3 Logan River at Yarrahappini (DNRM GS 145014a) ................................................. 41

5.6.4 Albert River at Bromfleet (DNRM GS 145102a) ....................................................... 42

5.6.5 Albert River at Wolffdene (DNRM GS 145196a) ...................................................... 43

5.6.6 Logan River at Macleans Bridge (BOM GS 040935) ................................................ 43

5.6.7 Logan River at Waterford (BOM GS 040878) ........................................................... 44

5.6.1 Wyaralong Dam Alert (540530) ................................................................................ 45

6. Model Development .................................................................................................................... 46

6.1 Model Description .............................................................................................................. 46

6.2 Model Configuration ........................................................................................................... 48

6.2.1 Catchment Subdivision ............................................................................................. 48

6.2.2 Land Use .................................................................................................................. 50

7. Model Calibration and Verification ............................................................................................ 52

7.1 Selection of Calibration and Verification Events ................................................................ 52

7.2 Calibration Methodology .................................................................................................... 53

7.3 Assignment of Rainfall and Temporal Patterns ................................................................. 53

7.4 Adopted Model Parameters ............................................................................................... 53

7.5 Initial and Continuing Losses ............................................................................................. 54

7.6 Calibration Results ............................................................................................................. 54

7.6.1 General Calibration Comments ................................................................................ 54

7.6.1 January 1974 Event.................................................................................................. 56

7.6.2 April 1990 Event ....................................................................................................... 57

7.6.3 February 1991 Event ................................................................................................ 58

7.6.4 January 2008 Event.................................................................................................. 59

7.6.5 January 2013 Event.................................................................................................. 60

7.7 Verification Results ............................................................................................................ 61

7.7.1 May 1980 Event........................................................................................................ 61

7.7.2 April 1988 Event ....................................................................................................... 62

7.7.3 March 2004 Event .................................................................................................... 63

7.7.4 January 2012 Event.................................................................................................. 64

8. Design Flood Estimation ............................................................................................................ 65

8.1 Methodology ...................................................................................................................... 65

8.2 Rainfall Depth Estimation .................................................................................................. 71

8.2.1 Frequent to Large Design Events (up to and including 100 years ARI) ................... 71

8.2.2 Rare to Extreme Design Events (200 to 2000 years ARI) ........................................ 72

8.2.3 Probable Maximum Precipitation Design Flood (PMPDF) ........................................ 73

8.2.4 Probable Maximum Flood (PMF) .............................................................................. 73


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8.3 Temporal Patterns ............................................................................................................. 73





8.4 Areal Reduction Factors .................................................................................................... 75





8.5 Rainfall Losses .................................................................................................................. 76





8.6 Spatial Distribution ............................................................................................................. 77





8.7 Design Discharges ............................................................................................................. 77





8.7.5 Comparison with Previous Studies ........................................................................... 84

9. Flood Frequency Analysis .......................................................................................................... 86

9.1 Method of Analysis ............................................................................................................ 86

9.2 Available data .................................................................................................................... 86

9.2.1 Peak Annual Data..................................................................................................... 86

9.2.2 Other Historical Data ................................................................................................ 87

9.3 Analysis and Results ......................................................................................................... 87

9.3.1 The Overflow ............................................................................................................ 87

9.3.2 Round Mountain ....................................................................................................... 89

9.3.3 Yarrahappini ............................................................................................................. 90

9.3.4 Bromfleet .................................................................................................................. 91

9.3.5 Wolffdene ................................................................................................................. 92

9.4 Comparison with URBS Results ........................................................................................ 93

10. Joint Probability Approach (Monte Carlo Simulation) ............................................................. 95

11. Conclusion ................................................................................................................................. 100


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11.1 Overview .......................................................................................................................... 100

11.2 Model Calibration and Verification ................................................................................... 100

11.3 Calibration Results ........................................................................................................... 101

11.4 Design Flood Discharges ................................................................................................. 102

11.5 Flood Frequency Analysis ............................................................................................... 103

11.6 Monte Carlo Simulation ................................................................................................... 104

12. Recommendations .................................................................................................................... 105

13. Reference ................................................................................................................................... 106

14. Appendix A – Logan River Catchment Sub Catchment Area and Land Uses ..................... 108

15. Appendix B – URBS Catchment Definition File ...................................................................... 114

16. Appendix C – Calibration and Verification Hydrographs ...................................................... 127

16.1 January 1974 calibration .................................................................................................. 127

16.2 April 1990 calibration ....................................................................................................... 131

16.3 February 1991 calibration ................................................................................................ 135



16.6 May 1980 Verification ...................................................................................................... 147

16.7 April 1988 Verification ...................................................................................................... 151

16.8 March 2004 Verification ................................................................................................... 155

16.9 January 2012 Verification ................................................................................................ 159

17. Appendix D – Design Temporal Patterns ................................................................................ 164

18. Appendix E – Design Event Hydrographs .............................................................................. 166

19. Appendix F – Monte Carlo Results .......................................................................................... 173


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2. Introduction

2.1 Overview

Over recent years, City developed numerous hydrological models of its catchments and waterways. These models have been developed by Council staff and/or consultants, using a range of approaches and assumptions. The standard of these models, with respect to their configuration, calibration, use for design discharge estimation and documentation, vary significantly.

To provide a consistent basis for floodplain management and local government planning, the City commissioned WRM Water & Environment (WRM) in December 2007 to undertake a major study to review and update its hydrological models to a consistent standard of methodology and documentation. Coomera, Nerang, Logan-Albert, Pimpama, Worongary, Mudgeeraba, Loders, Biggera, Tallebudgera and Currumbin catchment’s hydrological models were included in that study.

A comprehensive review of data, previous hydrological models and associated reports for the above 10 catchments covering the City were undertaken prior to the commencement of model updates. This review assessed all aspects of model development, calibration and use for the estimation of design discharges. Based on the review, a set of recommendations were provided to update the 10 models in a consistent manner across the city area using the latest data and modelling approaches. Details of the model review and its findings are given in WRM2008a (Ref. 1).

Based on WRM recommendations, City upgraded the hydrological model for Logan River Catchment using URBS modelling software in September 2009 (Ref. 2). The upgraded model is again reviewed in this study as per Don Carroll (2013) recommendation (Ref. 3). The upgrade involves combining four model segments (Teviot Brook, Upper Logan, Albert River and Lower Logan) into one Logan River model, a review of rating curves, model calibration, design rainfall, temporal patterns and undertaking of Monte Carlo simulation.

This report describes the development of the URBS hydrological model, calibration, flood frequency analysis (FFA), Monte Carlo simulation and design events simulation for Logan River Catchment.

2.2 Study Objectives and Scope

The main objective of the study was to develop a hydrological model for the Logan River catchment based on URBS hydrological modelling software (URBS), calibrated and verified against available data, and fully documented to a consistent standard. Once this objective was achieved, the calibrated model was used to estimate design flood discharges using a consistent methodology.

The scope of work was as follows:

Review existing models and data.

Update the existing model to a standard consistent with other catchments.

Review and update model calibration and verification.

Review and update FFA.


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Undertake Monte Carlo simulations.

Estimate design discharges for rare to extreme events at key locations throughout the catchment using current industry standard methodology.

Document the adopted methodology, tasks and results to a standard consistent with other updated models.

2.3 Limitation Statement

The following limitations apply in the preparation of this report.

This report was prepared based on available information at the time of writing.

The analysis and approach by this study is specifically prepared for internal use. Use of contents of this report is prohibited unless a written approval is obtained from City.

The result of this study is accurate only for its intended purpose.

2.4 Acknowledgement

The assistance provided by the Bureau of Meteorology, and Mr Jeff Perkins in particular, for this study is gratefully acknowledged. The Bureau provided the copies of their URBS hydrological models used for flood forecasting purposes and all the historical rainfall and stream flow data used in this study for model calibration and verification. Terry Malone of Seqwater provided relevant data of Wyaralong Dam and the Wyaralong Dam Alliance (WDA) report. His assistance is also gratefully acknowledged.

2.5 Previous Studies

There are many studies of relevance to the hydrological modelling of the Logan River catchment which are briefly described below.

2.5.1 Logan and Albert Rivers Flood Plain Modelling Study (1997) (Ref. 4)

Australian Water Engineering undertook a flood plain modelling study for the Logan-Albert River catchment in 1997. The study was undertaken for the Southern Region of Councils, comprising Logan City, City of Gold Coast, Beaudesert Shire and Redland Shire Councils. The hydrological modelling for this study was undertaken using the RAFTS model. This study updated two earlier studies undertaken using the RORB model in 1992 and 1994 for the Logan City Council by the same consultant. The RAFTS model was calibrated against the January 1974 and April 1990 flood events, and verified against the February 1976 and February 1991 flood events, at 3 gauging stations (Yarrahappini on the Logan River and Bromfleet and Wolffdene on the Albert River). The calibrated model was then used to estimate 10, 20, 50 and 100 year ARI design discharges as inflows into a hydraulic model (2007) of the lower Logan-Albert River system.

2.5.2 Wyaralong Dam, Design Flood Hydrology Report (2007) (Ref. 5)

In 2007, Sunwater developed a URBS model of the Teviot Brook catchment, which is tributary catchment of the Logan River, as part of their hydrological and hydraulic investigations for the proposed Wyaralong Dam. This model covers only the Teviot Brook catchment. This model was


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calibrated against the January 1974, February 1976 and February 1991 flood events at the Overflow gauging station, and used to estimate 2 year ARI to Probable Maximum Flood (PMF) design discharges into and out of the Wyaralong Dam.

2.5.3 Logan River Catchment Hydraulic Study (2007) (Ref. 6)

In 2007, City in association DHI Water & Environment developed a hydraulic model for the lower reaches of Logan River Catchment. The hydrological input of this study was based on AWE (1997) study (Ref. 4). The study identified a significant interaction of flood flows between Logan River and Pimpama River floodplains.

2.5.4 Logan River Flood Study (2009) (Ref. 2)

WRM was commissioned by City in 2008 to undertake a comprehensive study to review and update the hydrological models to a consistent methodology and to calibrate recent flood events. In this study, a URBS model was developed for the whole Logan River catchment and the catchment was divided into four segments; Upper Logan River, Teviot Brook, Albert River and Lower Logan River. The model was calibrated to three historical events (April 1990, February 1991 and January 2008) and verified to another three flood events (January 1974, May 1980 and April 1988). Four different sets of model parameters were used for each segment of the model. The calibrated model was used to estimate design discharges for the 2 to 2000 year ARI, PMPDF and PMF at different locations within the catchment. A flood frequency analysis was also undertaken using Log-Pearson Type III distribution at The Overflow, Round Mountain, Yarrahappini, Bromfleet and Wolffdene gauging stations.

2.5.5 Logan River Hydrological Study Addendum Report (2010) (Ref. 7)

City undertook a hydrological study in 2010 to refine the parameters and rainfall of the WRM 2009 study (Ref. 2). A new set of model parameters were adopted for the Lower Logan Catchment. The model parameters for the Upper Logan, Teviot Brook, and Albert River were kept unchanged to those of the WRM 2009 study.


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3. Catchment Description

3.1 Overview

The Logan River has its headwaters in the McPherson Ranges along the Queensland / New South Wales border and flows in a generally north-easterly direction towards the coast where it discharges into Moreton Bay at Jacobs Well. The Logan River catchment has a total area of approximately 3878 km2 and includes a number of significant tributaries including Teviot Brook, Slacks and Scrubby Creeks and the Albert River. Teviot Brook has a catchment area of 694 km2 at its confluence with the Logan River near Cedar Pocket. Slacks and Scrubby Creeks join the Logan River at Tanah Merah and have a combined catchment area of some 121 km2 to the confluence. The Albert River has a catchment area of 781 km2 and discharges into the Logan River at Eagleby.

The topography of the catchment varies from steep hills, valleys and mountainous terrain in the upper catchment to wide, flat floodplains in the middle and lower reaches of the river. Catchment elevations range from approximately 1350m in the McPherson Ranges to less than 2m at the river mouth. The catchment is scattered with many small storages (farm dams), several on-river weirs and a major dam (Maroon Dam) on Burnett Creek. Another major dam (Wyaralong Dam) was constructed on Teviot Brook in 2011. The major land uses are forest and pasture in the upper catchment and pasture and rural residential in the middle and lower catchments. Major urban centres are located at Logan City and Beenleigh on the north and south banks of the lower Logan River. The Logan River Catchment consists of Upper Logan River, Lower Logan River, Teviot Brook and Albert River. Figure 1 is a locality map of Logan River Catchment.

Version 3 TRACKS-#45737331-v3-LOGAN_RIVER_HYDROLOGICAL_STUDY_DECEMBER_2014 Page 17 of 175

Figure 1: Locality map, Logan Catchment


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3.1.1 Upper Logan Catchment

The upper Logan River catchment extends from the border ranges to the Yarrahappini gauge site at Cedar Pocket. It is characterised by steep hills, deep valleys and mountainous terrain. The topography flattens away from the Border Ranges, and a wide mature floodplain becomes evident.

The Upper Logan River has a catchment of some 2419 km2 to the Yarrahappini gauge. The catchment comprises the Logan River itself, which has its headwaters in Mount Barney National Park, and a number of tributary catchments including Running Creek, Christmas Creek and Burnett Creek, which rise in Lamington and Mount Barney National Parks and also Burnett Creek State Forest. Running Creek, Christmas Creek and Burnett Creek have catchment areas of 128 km2, 199 km2 and 198 km2 respectively. The upper Logan River’s major tributary, Teviot Brook, has a catchment area of some 694 km2 and joins the Logan River just upstream of the Cedar Grove Weir. The Teviot Brook catchment is discussed in detail in Section 3.1.3 . A number of other tributaries of varying size drain into the upper Logan between the Border Ranges and the Yarrahappini gauge site.

In the upper catchment, the Logan River itself is generally quite narrow (20m – 40m wide) and shallow (2m – 4m) with a sandy bed. The river experiences periods of little or no flow during extended dry weather periods. The channel slope in the upper reaches of the catchment is relatively steep, but flattens considerably in the floodplain area. The average channel slope from the upstream extent of the catchment to the Yarrahappini gauge site (some 135km) is approximately 0.1%. The average channel slope was calculated from 50m contours using the equal area slope method (QUDM, 1994 Figure 5.05.4).

The only existing significant storage in the entire Logan River catchment is Maroon Dam, which is located on Burnett Creek. The dam has a catchment area of 106 km2 and a capacity of 44,320 ML at full supply. Maroon Dam has little impact on flood flows in the Logan River. Bromelton Weir is located on the Logan River just upstream of Beaudesert, and is considered too small to have any impact on flood flows. Cedar Grove Weir was recently constructed on the Logan River near Cedar Pocket, upstream of the Yarrahappini gauge site. Similar to Bromelton Weir, Cedar Grove Weir is considered too small to have any major impact on flood flows. There are also significant numbers of small storages (farm dams) scattered throughout the upper Logan River catchment.

3.1.2 Lower Logan Catchment

The lower Logan River catchment extends from the Yarrahappini gauge site to the river mouth at Jacobs Well. The lower Logan catchment is characterised by flatter terrain and a wider mature floodplain. In the middle and lower reaches the river is wider and deeper, and is tidally affected in the lower reaches.

The Logan River has a catchment area of some 3856 km2 (3878 km2 including Behms Creek catchment) at the mouth. The lower Logan River catchment includes two major tributaries, the Slacks and Scrubby Creek system and the Albert River. Slacks and Scrubby Creek have a catchment area of some 121 km2 and flow through Marsden, Woodridge and Loganlea prior to entering the Logan River at Tanah Merah. The Albert River has a catchment area of approximately 721 km2 and joins the Logan River at Eagleby. The Albert River catchment is discussed in detail in Section 3.1.4 .

Throughout the lower catchment the Logan River is wider and deeper than the upper reaches, with a typical width of 60m to 150m, and depths of up to 10m. The channel slope in the lower reaches of the river is significantly flatter than the upper catchment, with an average channel slope of 0.01%. The


Page 19 of 175

average channel slope was calculated from City’s 5m DTM using the equal area slope method (QUDM, 1994 Figure 5.05.4).

There are no major storages located in the lower Logan River catchment. A number of small storages (farm dams) are located on the Logan River floodplain throughout the middle and lower areas of the catchment.

3.1.3 Teviot Brook Catchment

Teviot Brook is a major tributary of the Logan River, with a catchment area of 544 km2. The Teviot Brook catchment bears some similarities to the Upper Logan catchment, in that it is comprised of steep hills and valleys and mountainous terrain.

Teviot Brook has a relatively linear catchment shape, with few major tributaries. The headwaters of the watercourse are found in Teviot State Forest and Main Range National Park. The two major tributaries, Black Rock Creek and Woollaman Creek, have catchment areas of 88 km2 and 102 km2 respectively. Black Rock Creek joins Teviot Brook some 12 km upstream of Boonah (approximately 43 km upstream of The Overflow gauge site). Woollaman Creek enters Teviot Brook approximately 3km upstream of the Logan River confluence.

Teviot Brook is generally quite narrow (20m – 40m wide) and shallow (2m – 4m) with a sandy bed. The brook experiences periods of little or no flow during extended dry weather periods. The channel slope in the upper reaches of the catchment is relatively steep, but flattens considerably towards the Logan River confluence. The average channel slope from the upstream extent of the catchment to the confluence with the Logan River (some 105km) is approximately 0.2%. The average channel slope was calculated from 50m contours using the equal area slope method (QUDM, 1994 Figure 5.05.4).

Teviot Brook discharges into the Logan River just upstream of Cedar Pocket and the recently constructed Cedar Grove Weir. Wyaralong Dam was constructed in 2011 on Teviot Brook near Allenview, downstream of The Overflow gauge site. The Wyaralong Dam has a catchment area of 546 km2 and a capacity of 1202883 ML at full supply (Ref. 24 and http://www.seqwater.com.au/water-supply/dam-operations/wyaralong-dam ). There are significant numbers of small storages (farm dams) scattered throughout the Teviot Brook catchment.

3.1.4 Albert River Catchment

The Albert River is a major tributary of the Logan River, with a catchment area of some 781 km2. The upper catchment resembles the upper Logan catchment, with the Albert River headwaters rising in the mountains of Lamington National Park.

The Albert catchment is generally linear and includes two significant tributaries, Cainbable Creek and Canungra Creek. Cainbable Creek has a catchment area of 71 km2, and discharges into the Albert River approximately 4 km downstream of the Lumeah gauge site. Canungra Creek has a catchment area of some 136 km2 and joins the Albert River just upstream of the Bromfleet gauge site.

The Albert River is generally narrow and shallow in the upper regions of the catchment, and becomes wider and deeper closer to the Logan River confluence. The lower reaches of the Albert River are tidally affected. The average channel slope from the upstream extent of the catchment to the


Page 20 of 175

confluence with the Logan River (some 122 km) is approximately 0.2%. The average channel slope was calculated from City’s 5m DTM and 50m contours using the equal area slope method (QUDM, 1994 Figure 5.05.4).

There are a large number of small storages (farm dams) in the upper and middle Albert River catchment areas, but no major storages or weirs.

3.2 Land Use

The major landuse in the Upper Logan catchment is forest, with pasture becoming more prevalent on the flatter areas of the catchment. There are minor urban areas located at Beaudesert and Rathdowney. Landuses are expected to remain as forest and pasture except for minor urban expansion at Beaudesert.

The dominant landuse is pastoral in the middle reaches of the Lower Logan Catchment, with minor forested areas. Rural residential and urban landuses increase in the lower reaches of the river, including the major urban centres at Logan and Beenleigh. Urban landuses are expected to increase around these established urban centres.

The landuse in the Teviot Brook Catchment is a mix of forest and pasture, with a minor urban centre at Boonah. Landuses in this catchment are expected to remain as forest and pasture.

The upper region of the Albert River catchment features a mix of natural forest and pastures. The middle and lower areas of the catchment are flatter, with increasing pastoral landuses. There are significant urban landuses in the lower catchment at Beenleigh and towards the confluence with Logan River at Eagleby.

3.3 Stream Gauging Stations

Table 1 shows the key stream gauging sites in the Logan River (Teviot Brook, Upper Logan, Lower Logan and Albert River) catchment, the length of the channel and the catchment area draining to each site. The locations of the gauging sites are shown on Figure 1.

Table 1 - Stream gauge stations, Logan River Catchment

River Station Number (AWRC No)

Station Name Stream Name

Period of Operation

Gauge Zero

(m AHD a) /

State b

Channel Length (km)

Catchment Area (km2)

145003b Forest Home Logan River

10/01/1953 - present

107.823a 23.2 176.1

145020a Rathdowney Logan River

14/12/1973 - present

75.38 a 59.7 534.8

145010a Dieckmans Bridge Running Creek

26/11/1963 - present

(93.345)b 35.1 128.2

145013a Rudds Lane Christmas Creek

18/10/1967 - present

(87.532)b 30.7 158.6

145008a Round Mountain Logan River

7/01/1957 - present

(44.281)b 84.5 1264.1


Page 21 of 175

River Station Number (AWRC No)

Station Name Stream Name

Period of Operation

Gauge Zero

(m AHD a) /

State b

Channel Length (km)

Catchment Area (km2)

145014a Yarrahappini Logan River

21/04/1969 - present

(10.589)b 128.2 2419.5

040935 Macleans Bridge (Alert)

Logan River

01/12/1982 - present

3.31 a 143.8 2571.4

040878 Waterford (Alert) Logan River

25/11/1993 - present

0.00 a 174.9 2770.2

540078 First Ave, Marsden (Alert)

Scrubby Creek

24/03/1993 - present

0.00 a 11.6 64.6

540079 Slacks Creek, Reserve Pk

(Alert)

Slacks Creek

15/04/1993 - present

0.00 a 5.5 19.9

540091 Slacks Creek,

Loganlea Road Slacks Creek

14/04/1993 - present

0.00 a 19.7 105.3

540236 Riedel Rd,

Carbrook (Alert) Logan River

18/03/1998 - present

0.00 a 199.2 3771.5

145011a Croftby Teviot Brook

02/07/1966 - present

(161.815)b 15.6 82.6

040949 Boonah (Alert) Teviot Brook

15/06/1992 - present

79.387 a 44.1 317.3

145012a The Overflow Teviot Brook

03/10/1969 (41.227)b 75.2 501.8

145101d Lumeah #2 Albert River 10/01/1953 - present

(80.001)b 39.7 164.4

145107a Main Road Bridge (Benobble)

Canungra Creek

24/01/1973 - present

71.807 a 38.4 100.6

145102a Bromfleet Albert River 24/01/1973 - present

(28.30)b 66.7 543.6

145196a Wolffdene Albert River 21/04/1969 - present

-0.613 a 94.1 720.6

a Source: http://www.bom.gov.au/qld/flood/networks/section6.shtml; b State datum


Page 22 of 175

4. Methodology

The hydrologic modelling of the Logan River catchment was undertaken using an approach and methodology consistent with the other catchments in the City area. The study adopted a systematic approach and consisted of the following steps:

4.1 Comprehensive Review of Existing Models and Data

The specific tasks included:

Review of previous studies.

Review of existing WRM (2009) model.

Review of storage-discharge characteristics of Maroon Dam, Bromelton Weir and Cedar Grove Weir.

The inclusion of Wyaralong Dam.

Review of available rainfall and stream gauging data.

Review and update of key gauging station rating curves.

Review of existing land use data and an update of them based on current land uses identified from aerial photography and landuse planning scheme maps.

4.2 Model Construction


Update the URBS model configuration, includes combining four segments (Teviot Brrok, Upper Logan, Albert River and Lower Logan) into one model.

Delineation of catchment and sub-catchment boundaries based on the latest DTM and drainage network data for the Logan River catchment.

Generation of catchment (network) files with appropriate output locations and calibration locations for the URBS model.

Update model to reflect current land use in the catchment.

4.3 Model Calibration and Verification


Selection of calibration and verification events.

Processing of rainfall and streamflow data for calibration and verification events.

Rainfall analysis of all selected events to create sub-catchment specific rainfall to generate rainfall definition files for the URBS model.

Calibration and verification of the URBS model against historical flood events.


Page 23 of 175

Adoption of global model parameters for the Logan URBS model.

Adoption of uniform initial and continuing rainfall losses for the URBS model.

4.4 Design Discharge Estimation


Estimation of design rainfalls and loss rates for storm events ranging from 2 year ARI to PMPDF.

Undertaking of design event model runs for storm durations up to 120 hours and storm severities ranging from 2 year ARI to PMF.

Undertaking of flood frequency analysis for peak discharges in Teviot Brook at The Overflow, Logan River at Round Mountain and Yarrahappini and the Albert River at Bromfleet and Wolffdene.

Reconciliation of URBS model design events and FFA results.

Estimation of design discharges at key locations throughout the catchment for flood events ranging from 2 year ARI to PMF.

Verify the design discharges against Monte Carlo simulation

4.5 Joint Probability Approach/Monte Carlo Simulation


Undertake Monte Carlo simulations using both the CRC-CH and TPT method, for further verification of the discharges obtained from the Design Event Approach (DEA).

4.6 Preparation of Study Report

The specific tasks included the documentation of the adopted methodology, tasks and results to a standard that is consistent with other updated models.


Page 24 of 175

5. Available Data

5.1 Topographic Data

The topographic datasets available for this study were as follows:

City’s 5m grid DTM (covering City area.

1:250,000 topographic maps for the entire Logan River catchment.

1:25,000 topographic maps for parts of the catchment.

Department of Natural Resources and Mines (DNRM’s) GIS drainage network layer, showing all minor and major watercourses and water bodies throughout the catchment.

5.2 Land Use Data

The following land use datasets were available for the study:

Cadastral boundaries for City, Logan City, Beaudesert Shire and Redlands Shire.

Land use planning scheme maps for City and Logan City.

City GIS land use database information.

Aerial and Satellite photography.

5.3 Rainfall Data

Rainfall data for pluviograph and daily rainfall stations in and adjacent to the catchment was provided by the BOM. The rainfall data used in the previous AWE (1997) and Sunwater (2007) studies were not available.

5.3.1 Pluviograph Data

Table 2 shows the available pluviograph data from rainfall stations within and adjacent to the Logan River catchment for the selected model calibration and verification events (selection of these events is discussed in Section 7.1 ). Figure 2 shows the locations of the pluviograph stations. The following is of note with regards to the available pluviograph data:

A number of stations are repeated in Table 2 as they have been converted from telemetric and manual recording stations to alert stations (new station numbers have been assigned when such conversions have taken place).

There is little pluviograph data available for the 1974, 1980, 1988 and 1991 events. Further to this, very few of the available stations are within the Logan River catchment. The number of available pluviograph stations located within the catchment for each historical event is as follows:

o January 1974 – one available pluviograph within catchment (total of five available).

o May 1980 – two available pluviographs within the catchment (total of six available).


Page 25 of 175

o April 1988 – two available pluviographs within the catchment (total of 11 available).

o February 1991 – three available pluviographs within the catchment (total of four available).

The most pluviograph data (total of 41 available) were available for the January 2008 event.

Table 2 - Pluviograph Data Availability for the Logan River Catchment

Station No Station Name

Data Available

Jan 1974

May 1980

April 1988

April 1990

Feb 1991

Mar 2004

Nov 2004

Jan 2008

Jan 2012

Jan 2013

2106 The Gap AL - - - - Y - - - - -

7001 Springbrook

TM - - - Y - - - - - -

7007 Round

Mountain TM - - - Y - - - - - -

7009 The Overflow

TM - - - Y - - - - - -

7011 Yarrahappini

TM - - - Y - - - - - -

7074 Rudds Lane

TM - - - Y - - - - - -

7091 Darlington

TM - - - Y - - - - - -

7243 Beaudesert

TM - - - Y - - - - - -

7245 Boonah TM - - - Y - - - - - -

040004 Amberley

Aero. Y Y Y - - - - - - -

040014 Beaudesert - - - Y - - - - - -

040094 Harrisville

PO - - Y Y - - - - - -

040135 Moogerah

Dam Y Y Y Y Y - - - - -

040178 Rathdowney

PO - - Y Y Y - - - - -

040192 Springbrook

Forestry Y Y Y Y - - - - - -

040197 Mount

Tamborine Y Y Y Y - - - - - -

040211 Archerfield

Aero. - - Y - - - - - - -

040406 Beenleigh Bowls Club

Y - Y Y - - - - - -

040608 Benowa

WTP - - Y - - - - - - -

040609 Elanora WTP - - Y - - - - - - -


Page 26 of 175


Data Available

Jan 1974

May 1980

April 1988

April 1990

Feb 1991

Mar 2004

Nov 2004

Jan 2008

Jan 2012

Jan 2013

040659 Greenbank - - - Y - - - - - -

040676 Kooralbyn - Y - - Y - - - - -

040677 Maroon Dam - Y Y Y - - - - - -

040715 Shailer Park - - - Y - - - - - -

04033500 Mount

Tamborine - - - - - - Y Y Y Y

04034100 Wongawallan

Alert - - - - - - Y Y Y Y

04034500 Luscombe

Alert - - - - - - - Y Y Y

04076100 Wolffdene

Alert - - - - - - Y Y - Y

04078400 Calamvale

Alert - - - - - - - Y - Y

04078600 El Mark Alert - - - - - - Y Y Y -

04079300 The Gap

Alert - - - - - - - Y - -

04079300 Lyons Alert - - - - - - - Y - Y

04084400 Beechmont

Alert - - - - - - Y Y Y Y

04087600 Wilsons

Peak Alert - - - - - - Y Y - Y

04087800 Waterford

Alert - - - - - - Y Y - Y

04093000 Laheys

Lookout Alert - - - - - - Y Y Y Y

04093100 O'Reillys

Alert - - - - - - Y Y - Y

04093200 Darlington

Alert - - - - - - Y Y Y -

04093300 Foxley Alert - - - - - - Y Y Y Y

04093400 Romani Alert - - - - - - Y Y Y Y

04093500 Macleans

Bridge Alert - - - - - - Y Y Y Y

04093600 Lumeah Alert - - - - - - Y Y Y Y

04093700 Benobble

Alert - - - - - - - Y Y Y

04093800 Bromfleet

Alert - - - - - - Y Y Y Y


Page 27 of 175


Data Available

Jan 1974

May 1980

April 1988

April 1990

Feb 1991

Mar 2004

Nov 2004

Jan 2008

Jan 2012

Jan 2013

04093900 Beaudesert

Alert - - - - - - Y Y - Y

04094000 Yarrahappini

Alert - - - - - - Y Y Y Y

04094100 Kooralbyn

Alert - - - - - - Y Y Y Y

04094200 Palen Creek

Alert - - - - - - Y Y Y Y

04094300 Dieckmans Bridge Alert

- - - - - - Y Y Y Y

04094400 Rudds Lane

Alert - - - - - - Y Y Y Y

04094500 Round

Mountain - - - - - - Y Y Y Y

04094600 Rathdowney

Alert - - - - - - Y Y - Y

04094700 Croftby Alert - - - - - - Y Y Y Y

04094800 Knapps Peak

Alert - - - - - - Y Y Y Y

04094900 Boonah Alert - - - - - - Y Y Y Y

04095000 The Overflow

Alert - - - - - - Y - -

54007900 Slacks Creek (Reserve Pk)

- - - - - Y Y Y Y Y

54009100 Slacks Creek

(Loganlea - - - - - Y Y Y Y Y

54015100 Kalbar Weir

Alert - - - - - - Y Y Y Y

54019500 Washpool

Alert - - - - - - Y Y Y Y

54023300 Underwood (Millers Rd)

- - - - - Y Y Y Y Y

54023400 Stretton

(Gowan Rd) - - - - - Y Y Y Y

54023500 Hillcrest

(Wine Glass) - - - - - Y Y Y Y Y

54023600 Carbrook

(Riedel Rd) - - - - - - Y Y Y Y

54025500 Carbrook

Alert - - - - - - Y Y Y Y

Y - Data available - – Data not available


Page 28 of 175

5.3.2 Daily Data

Table 3 shows the available daily data from rainfall stations within and adjacent to the Logan River catchments for the selected model calibration and verification events. Figure 2 shows the locations of the daily rainfall stations. The following is of note with regards to the available daily rainfall data:

A number of stations are repeated between Table 2 and Table 3 as they have been converted from daily rainfall stations to pluviograph stations.

No daily rainfall data was used in the March 2004, November 2004, January 2008, January 2012 and January 2013 analysis.

Table 3 - Daily Rainfall Data Availability for the Logan River Catchment


Data Available

Jan 1974

May 1980

April 1988

April 1990

Feb 1991

7086 Foxley TM - - - Y -

7240 Canungra

TM - - - Y -

22007 Mount

Tamborine - - - Y -

040012 Barney View Y Y - - -

040014 Beaudesert Y Y Y - Y

040015 Beechmont - Y Y Y Y

040024 Boonah

(Stark Ave) Y Y Y Y Y

040042 Canungra

(Finch Ave) Y Y Y Y Y

040080 Foxley - Y - Y Y

040094 Harrisville

PO Y Y - - Y

040097 Hillview

(Christmas Y Y - - -

040104 Kalbar PO Y Y Y Y Y

040107 Bruff Hill Y Y - - -

040139 Mount Alford Y Y - - -

040141 Mount

Cotton West Y Y Y Y Y

040150 Mundoolun Y Y - Y Y


Page 29 of 175


Data Available

Jan 1974

May 1980

April 1988

April 1990

Feb 1991

040156 Innisplain - Y Y Y Y

040160 Nerang

(Gilston Rd) Y - - - -

040162 Numinbah State Farm

Y Y Y Y Y

040166 Oxenford (Oberon

Y Y - - Y

040167 Palen Creek Correctional

Y Y Y - -

040178 Rathdowney

PO Y Y - - -

040181 Roadvale Y Y - - -

040182 Green

Mountains Y Y Y Y Y

040190 Southport (Ridgeway

Y - Y - -

040196 Tallebudgera (Guineas Ck

Y - Y - -

040197 Mount

Tamborine - - - - Y

040198 Tarome Y Y Y Y Y

040211 Archerfield

Aero. Y - - Y -

040290 Maroon Y Y Y Y Y

040306 Loganlea - Y - - -

040312 New Beith Y Y Y Y Y

040394 Mount Barney

Y Y - Y Y

040404 Glenapp Y Y Y - Y

040406 Beenleigh Bowls Club

- Y - - Y

040407 Lumeah - Y Y Y Y

040410 Jacobs Well Y - - - -

040411 Romani

(Undullah) Y Y Y Y Y

040413 Central Kerry Y Y - Y Y

040439 Springbrook

(Alpine - Y - - -


Page 30 of 175


Data Available

Jan 1974

May 1980

April 1988

April 1990

Feb 1991

040454 Jimboomba (Glenlogan)

Y Y - - -

040460 Mount

Cotton (Uni) Y Y Y Y Y

040485 Wilsons

Peak Y Y Y Y Y

040487 Binna Burra Y Y Y Y Y

040490 Carneys Creek

Y Y Y Y Y

040523 Border Gate Y Y Y Y Y

040524 Little Nerang

Dam Y Y Y Y Y

040534 Wunburra Y Y Y Y Y

040535 Cainbable Y - - - -

040538 Tabragalba Y - Y Y Y

040542 Macleans

Bridge - - Y Y -

040550 Natural Bridge

Y Y Y Y Y

040583 Widgee Y Y Y Y Y

040610 Darlington - Y - Y Y

040677 Maroon Dam Y - - - -

041046 The Head Y - Y Y -

Y - Data available - – Data not available


Figure 2: Rainfall Station Location Map, Logan River Catchment


Page 32 of 175

5.4 Streamflow Data

Table 4 shows the available stream flow data from stream gauging stations located within the Logan River catchment for the selected model calibration and verification events (See Section 7.1 ). Figure 1 shows the locations of the stream gauges listed in Table 4.

The following is of note:

Some stream gauging stations have both Telemetry (DNRM) and Alert (BOM) data transmissions. The Alert and Telemetry stations are referred to by different station numbers; however it is understood that both record and transmit data from the same location and instrument. As a result some stations are repeated in Table 4 as they are listed under different station numbers.

Only DNRM stations have rating curves based on actual gauging. The maximum gauged height and/or gauged discharge for each of the DNRM stations is shown in Table 4. Rating curves for common BOM gauges are generally based on the original DNRM rating curve for the site, but some have been modified by BOM during calibration of their URBS models.

Some of the stations, including Wolffdene Alert, were malfunctioned during the January 2013 flood event (Table 4). However, manual data for the Wolffdene Alert for the event was available for this study.

An assessment of the available rating curves for each gauging station is given in Section 5.6 .

The key stream gauging stations used for calibration of the Logan River URBS model are listed below.

Logan River at Round Mountain (DNRM GS145008a)

Logan River at Yarrahappini (DNRM GS 145014a)


Albert River at Bromfleet (DNRM GS 145102a)

Albert River at Wolffdene (DNRM GS 145196a)

Logan River at Macleans Bridge Alert (BOM GS 040935)

Logan River at Waterford Alert (BOM GS 040878)

The calibration emphasis was given on the recorded data at the key gauge sites listed above. Due to a number of reasons, including lack of adequate upstream pluviograph data, rating curve quality concerns, missing or incorrect recorded data and insufficient number of upstream URBS sub-catchments, the remainder of the stream gauges listed in Table 4 were used only to achieve the general timing and shape of predicted hydrographs at the gauging stations.


Table 4: Stream gauge data availability, Logan Catchment

Station No Station Name Stream Name Catchment Area (km2)

Station Operator

Max. Gauged Height (m)

Max. Gauged Flow (m3/s)

Streamflow Data Available

Jan 1974

May 1980

April 1988

April 1990

Feb 1991

Mar 2004

Nov 2004

Jan 2008

Jan 2012

Jan 2013

145003b Forest Home Logan River 176.1 DNRM 3.10 - Y Y Y Y Y - - - - -

145020a Rathdowney Logan River 534.8 DNRM 8.09 - Y Y Y Y Y - Y - - Y

145010a Dieckmans Bridge

Running Creek 128.1 DNRM 4.10 - - Y Y Y Y - - - - Y

145013a Rudds Lane Christmas Creek 158.6 DNRM 3.72 - - Y Y Y Y - - - - Y

145008a Round Mountain Logan River 1264.1 DNRM 10.89 1047 Y Y Y Y Y - - - - Y

145014a Yarrahappini Logan River 2419.5 DNRM 18.36 2844 Y Y Y Y Y - - -

040832 Forest Home TM Logan River 176.1 DNRM - - - - - - - Y - Y - -

040946 Rathdowney Alert Logan River 534.8 BSC - - - - - - - Y - Y Y -

040943 Dieckmans Bridge Alert

Running Creek 128.1 BSC - - - - - - - Y - Y - -

040944 Rudds Lane Alert

Christmas Creek 158.6 BSC - - - - - - - Y - Y - -

040945 Round

Mountain Alert

Logan River 1264.1 BSC - - - - - - - Y Y Y Y -

040939 Beaudesert Alert Logan River 1464.7 BSC - - - - - - - - - Y - Y

040940 Yarrahappini Alert Logan River 2419.5 BSC - - - - - - - Y Y Y Y Y

145011a Croftby Teviot Brook 82.6 DNRM 3.58 - Y Y Y Y Y Y Y - - -



Station Operator




Jan 1974

May 1980

April 1988

April 1990

Feb 1991

Mar 2004

Nov 2004

Jan 2008

Jan 2012

Jan 2013

145012a The Overflow Teviot Brook 501.8 DNRM 9.67 390 Y Y Y Y Y - - - - -

040841 Croftby TM Teviot Brook 82.6 BSC - - - - - - - - - Y - Y

040949 Boonah Alert Teviot Brook 317.3 BSC - - - - - - - Y Y Y - Y

040950 The Overflow Alert Teviot Brook 501.8 BSC - - - - - - - Y Y Y - -

145101d Lumeah #2 Albert River 164.4 DNRM 7.84 380 Y Y Y Y Y - - - - -

145107a Main Road

Bridge (Benobble)

Canungra Creek 100.6 DNRM 3.71 148 Y Y Y Y Y - - - - -

145102a Bromfleet Albert River 543.6 DNRM 12.24 578 Y Y Y Y Y - Y - - - 145196a Wolffdene Albert River 720.6 DNRM 10.86 1214 Y Y Y Y Y - Y - - - 040936 Lumeah Alert Albert River 164.4 BSC - - - - - - - Y - Y - Y

540082 Beaudesert P/S TM Albert River 277.8 BSC - - - - - - - Y - Y - -

040937 Benobble Alert

Canungra Creek 100.6 BSC - - - - - - - Y - Y - Y*

040938 Bromfleet Alert Albert River 543.6 BSC - - - - - - - Y - Y Y Y

040761 Wolffdene Alert Albert River 720.6 BOM - - - - - - - Y - Y Y Y*

040935 Macleans Bridge Alert Logan River 2571.4 BSC - - - - Y Y Y Y Y Y Y Y*

040878 Waterford Alert Logan River 2770.7 LCC - - Y Y Y Y Y Y Y Y Y Y

040709 Eagleby Logan River 2920.2 BOM - - - - Y - Y - - - - - 540236 Carbrook Logan River 3771.5 LCC - - - - - - - Y - Y Y Y



Station Operator




Jan 1974

May 1980

April 1988

April 1990

Feb 1991

Mar 2004

Nov 2004

Jan 2008

Jan 2012

Jan 2013

(Riedel Rd) Alert

540078 Marsden

(First Ave) Alert

Scrubby Creek 64.6 LCC - - - - - - - - - Y - -

540079 Slacks Creek (Reserve Pk)

Alert Slacks Creek 19.9 LCC - - - - - - - - - Y - -

540091 Slacks Creek

(Loganlea Rd) Alert

Slacks Creek 105.3 LCC - - - - - - - - - Y - -

Y - Data available, Y*- Gauge malfunctioned - – Data not available


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5.5 Storage Data

5.5.1 Maroon Dam

Table 5 shows the adopted stage – storage – discharge relationship for Maroon Dam. Stage – storage and spillway elevation data for Maroon Dam were provided by Sunwater, and were based on a survey undertaken in 1996. The spillway discharge data were adopted from the existing BOM URBS model.

Table 5 - Adopted Stage – Storage – Discharge – Relationship, Maroon Dam

Stage Storage Spillway Discharge (m3/s)

177.6 0 0

179.6 15 0

181.6 301 0

183.6 1009 0

185.6 2049 0

187.6 3528 0

189.6 5410 0

191.6 7750 0

193.6 10573 0

195.6 14042 0

197.6 18045 0

199.6 22572 0

201.6 27601 0

203.6 33167 0

205.6 39267 0

207.14 44320 0

208.14 47755 266

209.14 51311 705

210.14 54980 1780

211.14 58767 3947

211.14 58767 3947

5.5.2 Bromelton Weir

Bromelton Weir is considered too small to have any significant impact on flood flows in the Logan River. In addition, there is little data available regarding the stage – storage – spillway discharge relationship for the weir. As a result, Bromelton Weir has not been included in the URBS model.


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5.5.3 Cedar Grove Weir

Table 6 shows the adopted stage – storage – discharge relationship for Cedar Grove Weir. Stage – storage data for Cedar Grove Weir was provided by DNRM, and were based on surveys undertaken in 1992, 1996 and 1998. The spillway level and discharge relationship was obtained from HEC-RAS modelling undertaken by Qld Water Infrastructure Pty Ltd (QWI). The QWI modelling indicates that the weir would be effectively drowned out at RL 26.4m.

It is of note that as construction of Cedar Grove Weir was completed in December 2007, the weir has been included in the URBS model for the January 2008, January 2012, January 2013 calibration events and design event modelling only.

Table 6 - Adopted Stage – Storage – Discharge – Relationship, Cedar Grove Weir

Stage Storage Spillway Discharge (m3/s)

14.0 0 0

15.0 9 0

16.0 54 0

17.0 154 0

18.0 325 0

19.0 580 0

20.0 931 0

20.5 1146 0

21.0 1389 28.0

21.5 1662 80.9

22.0 1965 142.7

22.5 2300 222.3

23.0 2667 311.9

23.5 3069 401.5

24.0 3507 491.0

24.5 3982 567.0

25.0 4492 641.5

25.5 5040 716.0

26.0 5629 790.4

26.5 6258 877.1*

* Weir effectively drowned at RL 26.4m

5.5.4 Wyaralong Dam

Table 7 and Table 8 show dam configuration and the stage-storage-discharge relationship of the Wyaralong Dam. The stage-storage-discharge relationship was provided by SEQwater and


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based on Wyaralong Dam Alliance Study 2009 (Ref. 24). The spillway discharges above 71.0 m AHD have been linearly interpolated and presented in Table 8. It is of note that as construction of Wyaralong Dam was completed in 2011, the dam has been included in the URBS model for the January 2012, January 2013 and design event flood modelling only.

Table 7 - Wyaralong Dam Details

Parameter Description / Value

Year completed 2011*

Catchment Area 546.0* km2

Length of Dam Wall 463.6* m

Full supply capacity 102883* ML (at 63.6 m AHD)

Primary spillway 63.6 m AHD (spillway length 135 m) (Ref. 24)

Secondary spillway 66.0 m AHD ( spillway length 150 m) (Ref. 24)

* http://www.seqwater.com.au/water-supply/dam-operations/wyaralong-dam

Table 8: Adopted Stage – Storage – Discharge – Relationship, Wyaralong Dam

Stage (m AHD) Storage (ML) Storage above spillway (ML)

Spillway Discharge (m3/s)

63.6 102883 0 0

64 107814 4931 58

64.5 114221 11338 201

65 120912 18029 401

65.5 127902 25019 647

66 135208 32325 937

66.5 142828 39945 1349

67 150748 47865 1863

67.5 158955 56072 2466

68 167446 64563 3157

68.5 176248 73365 3937

69 185452 82569 4807

69.5 195045 92162 5761

70 205034 102151 6792


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Stage (m AHD) Storage (ML) Storage above spillway (ML)

Spillway Discharge (m3/s)

70.5 215396 112513 7886

71 226117 123234 9031

71.5 237201 134318 10200a

72 248659 145776 11500

72.5 260548 157665 12600

73 272908 170025 13800

73.5 285720 182837 15000

74 298989 196106 16300

74.5 312721 209838 17600

75 326900 224017 18900

75.5 341477 238594 20200

76 356447 253564 21500

76.5 371817 268934 22800

77 387602 284719 24200

77.5 403792 300909 25600

78 420387 317504 26800

78.5 437387 334504 28200

79 454822 351939 29600

79.5 472700 369817 30950

80 491004 388121 32500 a The spillway discharges above 71.0 m AHD have been linearly interpolated

5.6 Rating Curves

DNRM (former NRW) supplied current and historical rating curves for the following key stations:

Teviot Brook at The Overflow (DNRM GS 145012a).

Logan River at Round Mountain (DNRM GS 145008a).

Logan River at Yarrahappini (DNRM GS 145014a).

Albert River at Bromfleet (DNRM GS 145102a).


Rating curves for all key stream gauging stations within the Logan River catchment were also available from the BOM URBS model. Of these, the BOM adopted rating curves for the above five stations are generally modified DNRM rating curves. For the other two key stations (Logan River at


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Macleans Bridge and Waterford) BOM has developed rating curves from correlations between their URBS model predictions and recorded peak flood heights.

Rating curves for each of the key gauging stations identified in Section 5.4 are assessed in detail below.

5.6.1 Teviot Brook at The Overflow (DNRM GS 145012a)

The available and adopted rating curves for The Overflow station are shown in Figure 3. Sunwater undertook a detailed review of the rating curve for The Overflow as part of their Wyaralong dam hydrology investigations (Sunwater, 2007) (Ref. 5). The Sunwater (2007) study included the following:

A review of all available rating curves for the station from both DNRM and BOM.

Construction of a hydraulic model to investigate the accuracy of available rating curves at high flows.

Generation of a composite rating curve, combining the actual gauged flows with the results of the hydraulic modelling.

The WRM (2009) study (Ref. 2) was adopted the Sunwater (2007) curve for this station. The Sunwater (2007) rating curve has been adopted for this study as well. It is of note that all rating curves reviewed were the same up to the maximum gauged flow of 390m3/s (9.67m gauge height).

Figure 3: Available and Adopted Rating Curves, Teviot Brook at The Overflow (DNRM GS 145012a)

5.6.2 Logan River at Round Mountain (DNRM GS 145008a)

The available and adopted rating curves for Round Mountain are shown in Figure 4. The rating curves available for this station did not perform well at this station probably due to datum issue.


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Therefore the rating curve at this station has been revised and the revised rating curve (Ref. 3) generated excellent calibration results for all historical events.

Figure 4: Available and Adopted Rating Curves, Logan River at Round Mountain (DNRM GS 145008a)

5.6.3 Logan River at Yarrahappini (DNRM GS 145014a)

The available and adopted rating curves for Yarrahappini are shown in Figure 5. The DNRM rating curve for Yarrahappini is based on gauged data up to 2844m3/s (18.36m gauge height). The rating has been extrapolated above this point by both DNRM and BOM. Running the model with the BOM rating curve produces a better fit with the recorded hydrograph. Therefore the BOM rating curve has been adopted for this study; however it has been extrapolated further between 5000m3/s and 9946m3/s based on the DNRM curve.


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Figure 5: Available and Adopted Rating Curves, Logan River at Yarrahappini (DNRM GS 145014a)

5.6.4 Albert River at Bromfleet (DNRM GS 145102a)

The available and adopted rating curves for Bromfleet are shown in Figure 6. The DNRM rating curve for Bromfleet is based on gauged data up to 578m3/s (12.24m gauge height). The rating has been extrapolated above this point by both DNRM and BOM. The BOM has adopted the DNRM curve for this station. The DNRM rating curve has been adopted for this study.

Figure 6: Available and Adopted Rating Curves, Albert River at Bromfleet (DNRM GS 145102a)


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5.6.5 Albert River at Wolffdene (DNRM GS 145196a)

The available and adopted rating curves for Wolffdene are shown in Figure 7. The DNRM rating curve is based on gauged data up to 1214 m3/s (10.86m gauge), and is extrapolated above this point. The BOM rating curve has been derived based on the correlation between recorded water levels and URBS model results. The DNRM rating curve produces peak discharges and volumes that are too high for the January 1974 event. These discharges and volumes cannot be reproduced by the URBS model even with zero rainfall losses. Further, the consistency between the discharge hydrographs at the upstream gauging station at Bromfleet and the Wolffdene station are poor if the DNRM rating curve is adopted. This indicates that the DNRM rating curve is inaccurate at high discharges. The URBS model results using the BOM rating curve produces consistent results between Bromfleet and Wolffdene. As such the BOM rating curve has been adopted for this study.

Figure 7: Available and Adopted Rating Curves, Albert River at Wolffdene (DNRM GS 145196a)

5.6.6 Logan River at Macleans Bridge (BOM GS 040935)

The adopted rating curve for Macleans Bridge is shown in Figure 8. A DNRM rating curve is not available for this gauging site. The BOM rating curve at Macleans Bridge has been derived based on a correlation between recorded water levels and BOM URBS model results. WRM (2009) (Ref. 2) adopted the BOM rating curve for this station. Subsequently, the BOM rating curve has been adopted in this study for this station.


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Figure 8: Available and Adopted Rating Curves, Logan River at Macleans Bridge (BOM GS 040935)

5.6.7 Logan River at Waterford (BOM GS 040878)

The adopted rating curve for Waterford is shown in Figure 9. A DNRM rating curve is not available for this station. The BOM rating curve at Waterford has been derived based on a correlation between recorded water levels and BOM URBS model results. The WRM (2009) (Ref. 2) adopted the BOM rating curve for this station. The BOM rating curve has been further modified based on correlation between water levels and URBS model results and adopted for this study.

It is noted that this station does not appear to pick up all flows above 700m3/s. Above this flow, it appears that some of the flow overflows from the Logan River and enters Pookgoor Creek, bypassing the gauging station. The bypassing flows re-enter the Logan River a short distance downstream of the gauging station. The adopted rating curve does not include any bypass flows.


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Figure 9: Available and Adopted Rating Curves, Logan River at Waterford (BOM GS 040878)

5.6.1 Wyaralong Dam Alert (540530)

The rating curve obtained from SEQwater is used for this study (Figure 10). The spillway rating is based on a primary spillway of 135 m long at an elevation of 63.6 m AHD and a secondary spillway of 150 m length at an elevation of 66.0 m AHD (WDA report, Ref. 24).

Figure 10: Available and adopted Rating Curve, Teviot Brook at Wyaralong Dam (540530)


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6. Model Development

6.1 Model Description

URBS is a networked (i.e. sub-catchment based) runoff-routing model that estimates flood hydrographs by routing rainfall excess through a module representing the catchment storage. In URBS, the storages are arranged to represent the drainage network of the catchment. The distributed nature of storage within the catchment is represented by a separate series of concentrated storages for the main stream and for major tributaries to provide a degree of physical realism. The storages in the model are generally non-linear, but linear storages can be used.

The model provides a number of options for conceptualising the rainfall-runoff process. Rainfall excess is first estimated from rainfall data using one of several available techniques (i.e. loss models) before being applied to the runoff-routing component of the model to compute the surface runoff hydrograph. Baseflow, if significant, is estimated separately and added to the surface runoff hydrograph to provide the total catchment hydrograph. The model can easily incorporate the effects of land use change, construction of reservoirs, changes to channel characteristics and other changes in the catchment.

The model provides different options for runoff routing. The user is given the option of lumping the catchment runoff and channel flow components into a single routing component or modelling them as separate routing components. The latter option (i.e. the ‘Split’ model) was adopted for the Pimpama River catchment.

In the Split model the rainfall excess for each sub-catchment is first determined by subtracting losses from the rainfall hyetograph. The rainfall excess is then routed through a conceptual catchment storage to determine the local runoff hydrograph for the sub-catchment. The storage - discharge relationship for catchment routing is:

m2

2

catch Q)U1(

)F1(AS

Where Scatch is the catchment storage (m3 h/s);

is the catchment lag parameter;

A is the area of sub-catchment (km2);

U is the fraction urbanisation of sub-catchment;

F is the fraction of sub-catchment forested; and

m is the catchment non-linearity parameter.

In the above equation, β is determined during model calibration and is a global parameter.

The local runoff hydrograph is then combined with runoff from the upstream sub-catchment and routed through channel storage to obtain the outflow hydrograph for the sub-catchment. Channel


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routing is based on the non-linear Muskingum Model. The channel routing storage-discharge relationship is given by:

ndu

c

chnl ))1((* QxQxS

LnfS

Where Schnl is the channel storage (m3 h/s);

α is the channel lag parameter

f is the reach length factor;

L is the length of reach (km);

Sc is the channel slope (m/m);

QU is the inflow at upstream end of reach (includes catchment inflow) (m3/s);

Qd is the outflow at downstream end of the channel reach (m3/s);

x is the Muskingum translation parameter;

n is the Muskingum non-linearity parameter (exponent); and

n* is the Manning's 'n' or channel roughness.

In the above equation, α and f are the principal calibration parameters. Note also that α is a global parameter, whereas f can be varied for each channel reach.

URBS allows the user to select one of several standard loss models. The available options are: initial and continuing loss model, proportional loss model, Manley-Phillips infiltration model and water balance model. The initial and continuing loss model was adopted for the Logan River catchment. This model assumes that there is an initial loss of ‘il’ mm before any rainfall becomes runoff. After this, a continuing loss rate of ‘cl’ mm per hour is applied to the rainfall, subject to the limit of the soil infiltration capacity (IFmax). The loss rates can be specified ‘globally’ to the entire catchment or ‘individually’ to each sub-catchment. Global loss values were adopted for the Pimpama River catchment.

Full details of the URBS model and its features are given in the URBS User Manual (Ref. 9).


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6.2 Model Configuration

6.2.1 Catchment Subdivision

In WRM (2009) (Ref. 2), the Logan River URBS model was divided into four URBS sub-models – Upper Logan, Teviot Brook, Albert River and Lower Logan. The Logan River URBS model (Ref. 2) formed the backbone of the current model. However in this study, the WRM’s four sub-models have been combined in a single model and sub catchment ID’s of Upper Logan, Lower Logan and Albert River has been prefixed to avoid duplication. Based on recommendations in WRM (2008a) (Ref. 1), the model parameters were kept global for the whole model, and the model configurations were kept as simple as possible. Figure 11 shows the configuration of the Logan River catchment URBS model. It is of note that the URBS models have been configured based on current catchment land uses only. The Logan River URBS model consists of 251 main sub-catchments.

The Teviot Brook catchment consists of 32 (IDs 1 - 32) sub-catchments and includes the entire catchment of Teviot Book upstream of the Wyaralong Dam site. The Wyaralong Dam is included at sub-catchment 32. The remaining catchment area downstream of the dam site to the confluence with the Logan River forms part of the Upper Logan URBS model.

The Upper Logan catchment consists of 103 (IDs 101 – 203) sub-catchments and includes the entire Logan River catchment upstream of the Yarrahappini gauge site. The Upper Logan also includes the catchment of Teviot Brook downstream of the Wyaralong Dam site. Maroon Dam is included in the model at sub-catchment 104 (Section 5.5.1 ). Cedar Grove Weir is included in the model at sub-catchment 201, however it only operates for the January 2008, January 2012, January 2013 calibration and design event runs. The weir is included as per Section 5.5.1 .

The Albert River catchment consists of 48 (IDs 401 – 448) sub-catchments and includes the entire catchment of the Albert River upstream of the Wolffdene gauge site. The remaining catchment area downstream of Wolffdene to the confluence with the Logan River forms part of the Lower Logan River catchment.

The Lower Logan River catchment consists of 61 sub-catchments and includes the entire Logan River catchment downstream of the Yarrahappini gauge site. Although Behms Creek does not drain into the Logan River, the catchment of Behms Creek is also included in the model, in order to provide local inflow hydrographs for the Logan River hydrodynamic model. The Behms Creek catchment consists of seven additional sub-catchments. During calibration additional storage routing was added upstream of Macleans Bridge and Waterford in order to achieve attenuation of flows exhibited in recorded data. The URBS Factor command was to account for differences in catchment slope between the Slacks & Scrubby Creek catchment and the Lower Logan River floodplain area. It is of note that the existing detention basins in the Slacks & Scrubby Creek catchment have not been included in the model as they are too small to have any impact on Logan River flood discharges. Appendix A (Ref. 14) shows the Logan River Catchment sub-catchment areas and land uses. The Logan River URBS catchment definition file is given in Appendix B (Ref. 15).


Figure 11: Logan River Catchment URBS model configuration


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6.2.2 Land Use

Table 9 shows the adopted five major land use categories for the purpose of URBS modelling, and how these land use categories correspond to the different land classifications in the City are also shown in the table.

Table 9 - Logan River land use categories

URBS Model Land Use Classification City of Gold Coast Classification

UF (Forested) o Forest

o Forest/Grassland

UR (Rural Land) o Grassland _ Urban/Suburban

o Grazing

o Open _ Ground

o Recreation (Facilities & Sub/Urban Parks)

o Rural _ Residential

o Tourism _ Recreation Park

o Vacant _ Land

o Waste _ Disposal

UH (High Density Urban)a o Access _ Restriction Strip

o Commercial

o Constructed Waterway _ Lake

o Industrial

o Marina

o Residential Choice

o Tourism _ Accommodation

o Transport (Rail, Road & Paved Areas)

o Utilities _ Infrastructure

o Water

o Wetlands

UM (Medium Density Urban) o Detached Dwelling

UL (Low Density Urban) o Park Living

o Tourism _ Caravan Park

UL/UM/UHb o Highly Disturbed _ Under Development

o Urban Residential a - Roads are included in this category. b - Appropriate classification selected based on aerial photos and site inspections.

Of the five different land uses, four relate to the amount of urbanisation in the catchment, affecting both the per cent imperviousness (losses) and the routing characteristics. The forested land use only affects the routing characteristics.

Table 10 shows the adopted land use breakdown for the Logan River Catchment URBS model. The adopted land uses reflect current catchment conditions.


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Table 10 - Adopted Land Use Breakdown, Logan River URBS Models

Catchment Catchment Area (km2)

Percent Forested (%)

Percent Rural Land (%)

Percent Urban High Density

(%)

Percent Urban Medium Density

(%)

Percent Urban Low

Density (%)

Teviot Brook 543.6 32.2 67.2 0.0 0.0 0.6

Upper Logan 1875.9 38.5 61.0 0.2 0.0 0.3

Albert River 720.6 49.1 50.2 0.5 0.0 0.3

Lower Logan 737.5 25.1 59.9 3.9 0.7 10.3


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7. Model Calibration and Verification

7.1 Selection of Calibration and Verification Events

Calibration data used in the Logan River Hydrology study 2009 (Ref. 2) were available for use in the current study. All the available data were sourced from BOM for a total of 24 flood events between 1947 and 2008. Data for two recent flood events, January 2012 and January 2013, were also available from BOM. The available rainfall and stream flow data for early events are very limited and of poor quality. Therefore the selected calibration and verification events are generally the most recent events, with the exception of the January 1974 event, which is the largest on record. The selected events are as follows:

Calibration:

o January 1974

o April 1990

o February 1991

o January 2008

o January 2013

Verification:

o May 1980

o April 1988

o March 2004

o January 2012

The selected events cover a wide range of discharges across all of the modelled catchments. Table 11 shows the recorded peak discharges for each event at each of the key gauging stations used for model calibration and verification.

Table 11 – Recorded Peak Discharges Calibration and Verification events

Gauging Station Name

Gauging Station No

Recorded Peak Discharge (m3/s)

Jan

1974

May 1980

April 1988

April 1990

Feb 1991

Mar 2004

Jan 2008

Jan 2012

Jan 2013

The Overflow

145012a 1075.0 73.0 440.0 223.5 1172.5 37.5 171.5 NA NA

Round Mountain

145008a 1606.8 598.0a 797.0 707.0 2448.5 675.0 1680.0 602.0 1510.0

Yarrahappini 145014a 3750.0 844.2 911.6 1048.7 2795.0 463.0 1247.2 585.9 2110.0

Bromfleet 145102a 1673.8 667.0 406.7a 621.2 332.2 671.1 1065.2 908.2 1108.3

Wolffdene 145196a 2371.8 901.2 635.2 859.4 258.0a 622.4 715.2 835.6 1174.0b

Macleans Bridge

040935 NA NA 977.6 1019.0 2570.0 415.0 1102.5 593.8 NA

Waterford 040878 5105.0 1020.0 1100.0 1190.0 2127.3a 467.8 892.0a 610.4 2088 a Accuracy uncertain, b based on manual data provided by BOM, the station was malfunction during the event


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7.2 Calibration Methodology


Due to the lack of available rainfall data for most events and the lack of detailed rainfall data where data were available, the URBS model cannot be expected to accurately reproduce flood behaviour for all events and at all gauging stations. As such calibration emphasis was placed more on large events, as the accuracy of small events are impacted significantly by spatial and temporal variation in rainfall. A single set of model parameters (α, β, m and forest factor F) were adopted for the whole model, and maintained for all calibration and verification events. The model parameters were adjusted to achieve the best calibration across all events, resulting in a compromise between model accuracy and model simplicity. It is noted that calibration of the model for gauging stations in different part (Teviot Brook, Upper Logan, Albert River and Lower Logan) of the Logan River catchment can be improved by adopting different sets of model parameters for each part of the catchment. Further, the calibration of the models for individual events can be improved by adopting a different set of model parameters for each of the different events.

Rainfall losses were adjusted to achieve the best possible hydrograph shapes and flood volumes. A uniform initial loss and continuing loss rate were adopted for the model and each flood event. Where necessary, reach length factors (f) were changed in the model to represent differences in channel routing characteristics. Again it is noted that calibration of the models for individual events can be improved by adopting variable initial and continuing losses across the catchment.

7.3 Assignment of Rainfall and Temporal Patterns

Pluviographs for each sub-catchment were generated from available pluviograph and daily rainfall station data using an inverse distance squared method based on the nearest four rainfall stations to the sub-catchment centroid. The nearest available pluviograph temporal pattern was adopted for the daily stations. This method ensures that all of the available data are used, and that the rainfall pattern for the nearest pluviograph is assigned to the sub-catchment.

7.4 Adopted Model Parameters

Table 12 shows the global catchment and channel parameters adopted for the Logan River catchment. The same parameter values were applied for all calibration and verification events.

Table 12 – Adopted catchment and channel parameters, Logan River catchment







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It is noted that reach length factors were introduced within the URBS model to represent differences in channel routing characteristics between the upper and lower reaches of the drainage system.

7.5 Initial and Continuing Losses

Table 13 shows the adopted initial loss and continuing loss rates for the Logan URBS model for calibration and verification events. It is of note that losses across the Logan River catchment were adjusted to produce the best calibration, and as such the amount and quality of available rainfall data for each event will have some effect on the adopted initial and continuing losses.

Table 13 - Adopted Initial and Continuing Losses for Calibration and Verification Event

Event Initial Loss

(mm)

Continuing Loss (mm/hr)

January 1974 20 1.4

April 1990 25 2.0

February 1991 30 2.5

January 2008 65 6.8

January 2013 70 4.25

May 1980 45 3.5

April 1988 50 0.8

March 2004 35 2.0

January 2012 35 5.0

7.6 Calibration Results

7.6.1 General Calibration Comments

Satisfactory calibration was achieved throughout the catchment, with the URBS models generally reproducing recorded flood discharges adequately. The model calibration is considered generally good, considering that a single set of global parameters were adopted across the whole Logan River catchment, consisting Teviot Brook, Albert River, Upper Logan and Lower Logan catchments. Moreover a single set of initial loss and continuing losses were used for the whole Logan Catchment. A compromise among gauging station predictions in terms of calibration emphasis was adopted in order to achieve the best possible overall calibration. General comments with respect to each part of the catchment is given below.


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(i) Teviot Brook

The model calibration for Teviot Brook is generally good, considering that a single set of global model parameters were adopted across all nine historical events. The model calibration results for large events are excellent; however, the model results for smaller events show the predicted flood peak arriving earlier than the recorded peak. This issue could be addressed, if necessary, by adopting different model parameters, including initial and continuing losses for smaller events.

ii) Albert River

The model calibration at the Broomfleet and Wolffdene is generally good even though there are some inconsistencies between recorded peak discharges at Bromfleet and Wolffdene. The model predicted excellent result at Broomfleet and Wolffdene; however, results show an early peak for smaller events.

(iii) Upper Logan

The model calibration for the Upper Logan catchment is generally excellent. Although calibration for the large events (January 1974, April 1990 and February 1991) was generally quite good at both Yarrahappini and Round Mountain gauging stations, the model predicted a lower peak at Round Mountain and a slightly higher peak at Yarrahappini for smaller events (January 2008 and January 2013).

(iv) Lower Logan

The quality of available data (both rainfall and stream flow) for the Lower Logan catchment is not as good as for the upstream of the catchment. For the January 1974, May 1980 and April 1990 flood events, the complete water level hydrographs were not recorded at the Macleans Bridge and Waterford gauges (the recorded water level hydrograph at Waterford for the January 1974 flood has been synthesised based on debris marks at the gauge site). Complete recorded water level hydrographs at both stations were available for the April 1988, February 1991, January 2008, January 2012 and January 2013 events.

The two gauging stations with available data (Macleans Bridge and Waterford) are BOM flood forecasting stations, not DNRM stations, and as such the quality of rating curves for these two stations is uncertain. The BOM rating curve at Waterford was updated based on correlation of recorded water level and URBS model discharge to improve calibration. The rating curve for Macleans Bridge appears to be acceptable; however the quality of Waterford rating is still uncertain, especially for higher discharges. As a result the calibration is generally good at Macleans Bridge, but somewhat poor at Waterford, except for the January 2013 flood event.

The Waterford gauge is tidally affected, and may also be affected by downstream water levels (including Albert River outflows). It also appears that the Waterford gauge does not pick up the total discharge, as some flow bypassing seems to occur above discharges of about 700m3/s, into Pookgoor Creek, located on the eastern overbank upstream of the Albert Street bridge. Water overflowing from the Logan River into Pookgoor Creek would bypass the Waterford gauge and re-enter the river a short distance downstream. Further, there is off-stream storage immediately upstream of the Waterford gauge site which may also contribute to reduced flood volumes in the river at the Waterford gauge. At large flows (such as the January 1974 flood), it is likely that Pookgoor Creek forms part of the Logan River floodplain, and acts as a single body of water.

The timing and shape of the predicted hydrographs at Waterford is generally acceptable but the predicted peak discharges are generally higher than recorded peak flows for the larger events.


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Predicted peak discharges at Macleans Bridge are generally good, indicating a problem with the Waterford rating curve. Further, the recorded flood volumes at Waterford appear to be less than those recorded at Macleans Bridge. Adding additional storage routing to the model between the two gauging stations does not resolve the issue.

7.6.1 January 1974 Event

A comparison of recorded and modelled peak discharges at key gauging stations for the January 1974 event are shown in Table 14. Calibration hydrographs at all key gauging stations for the January 1974 event are provided in Appendix C (Section 16.1 ).

Table 14 - Modelled and recorded peak discharges at key gauging stations, January 1974 flood event


Gauging Station No

Stream Name

Peak Discharge

Recorded (m3/s)

Modelled (m3/s)

The Overflow 145012a Teviot Brook 1075.0 1077.1

Round Mountain 145008a Upper Logan 1606.8 1606.8

Yarrahappini 145014a Upper Logan 3750.0 3982.0

Bromfleet 145102a Albert River 1673.8 1797.4

Wolffdene 145196a Albert River 2371.8 2371.8

Macleans Bridge 040935 Lower Logan NA 3655.7

Waterford 040878 Lower Logan 5105.0a 3633.1

a The recorded peak is based on debris marks at the gauge, and the flood hydrograph for this event is unavailable.

The following is of note with regards to the January 1974 calibration:

The January 1974 flood can be considered a large event in the overall the Logan River catchment.

In Teviot Brook the calibration is excellent, with the predicted hydrograph at The Overflow accurately reproducing recorded peak discharges, flood volumes and flood timing.

The Upper Logan verification for the January 1974 event is very good, with the predicted hydrograph at Round Mountain returning a peak discharge and volume. The predicted hydrograph at Yarrahappini matches the recorded hydrograph reasonably well for shape and peak discharge. The predicted flood volume at Yarrahappini is slightly less than the recorded hydrograph.

The January 1974 Albert River model calibration is acceptable, with the predicted hydrograph at Bromfleet matching well with the hydrograph shape. However the predicted flood volume and peak discharge are slightly higher than recoded flood volume and peak discharge at this station. An excellent calibration result is achieved at Wolffdene with respect to peak discharge, volume and shape of hydrograph.

There are no data available for Macleans Bridge, and the peak discharge at Waterford has been determined from a surveyed debris mark. The timing of flood peak at Waterford appears satisfactory, however the model predicted flood peak did not match with the recorded flood peak.


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7.6.2 April 1990 Event

A comparison of recorded and modelled peak discharges at key gauging stations for the April 1990 event are shown in Table 15. Calibration hydrographs at all key gauging stations for the April 1990 event are provided in Appendix C (Section 16.2 ).

Table 15 - Modelled and recorded peak discharges at key gauging stations, April 1990 flood event


Gauging Station No

Stream Name

Peak Discharge

Recorded (m3/s)

Modelled (m3/s)






Macleans Bridge 040935 Lower Logan 1019.0a 1129.0

Waterford 040878 Lower Logan 1190.0 1099.4

a The recorded hydrograph appears to have failed to record the flood peak accurately

The following is of note with regards to the April 1990 calibration:

The April 1990 flood can be considered a small event in the Teviot Brook and Upper Logan catchments; and a moderate event in the Albert River and Lower Logan catchments.

In Teviot Brook, the calibration is generally good with regards to peak discharge and flood volume; however the predicted flood peak at The Overflow is some 12 hours earlier than the recorded flood peak. This is due to the small nature of the April 1990 flood, and the fact that the adopted channel lag parameter is based on larger floods and whole Logan catchment. The April 1990 calibration in Teviot Brook can be improved by increasing the channel lag parameter for this event.

The Upper Logan calibration for the April 1990 event is excellent, with predicted hydrographs at both Round Mountain and Yarrahappini matching adequately with recorded hydrographs. The predicted peak discharge is slightly high at Round Mountain and Yarrahappini. However, the predicted flood peak timing and volume at both gauges is satisfactory.

The Albert River model calibration is also generally good, with predicted hydrographs at Bromfleet and Wolffdene matching adequately with recorded hydrographs. The predicted flood peak timing at Bromfleet is excellent, and only marginally early at Wolffdene.

The April 1990 calibration for the Lower Logan is considered acceptable. The Macleans Bridge gauge did not pick up the peak or the falling limb of the flood hydrograph, as the gauge appears to have failed at approximately midnight on the 5th April. The predicted hydrograph at Macleans Bridge adequately reproduces the timing and shape of the rising limb of the recorded hydrograph. The predicted hydrograph at Waterford shows a lower peak discharge than the recorded hydrograph. The quality of the recorded hydrograph at Waterford is unknown.


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7.6.3 February 1991 Event

A comparison of recorded and modelled peak discharges at key gauging stations for the February 1991 event are shown in Table 16. Calibration hydrographs at all key gauging stations for the February 1991 event are provided in Appendix C (Section 16.3 ).

Table 16: Modelled and recorded peak discharges at key gauging stations, February 1991 flood event


Gauging Station No

Stream Name

Peak Discharge

Recorded (m3/s)

Modelled (m3/s)





Wolffdene 145196a Albert River 258.0a 504.2

Macleans Bridge 040935 Lower Logan 2570.0 2677.9

Waterford 040878 Lower Logan 2127.3bb 2572.8 a The recorded hydrograph appears incomplete and does not accurately record the flood peak or the falling limb. b The recorded hydrograph does not include bypass flows to Pookgoor Creek.

The following is of note with regards to the February 1991 calibration:

The February 1991 flood can be considered a large event in Teviot Brook and the Upper and Lower Logan catchments; and a small event in the Albert River catchment.

In Teviot Brook, the calibration is excellent, with the predicted hydrograph at The Overflow accurately reproducing recorded peak discharges, flood volumes and flood timing.

The Upper Logan calibration for the February 1991 event is good, with the predicted hydrograph at Round Mountain matching reasonably well with peak discharges, the timing and shape of the rising and falling limbs of the recorded hydrograph. The lumpy, peaky shape of the Round Mountain recorded hydrograph indicates a possible problem with the record. The predicted hydrograph at Yarrahappini peak discharge, volume and shape are excellent, however the peak discharge arrives approximately 8 hours later than the recorded flood peak.

The February 1991 Albert River model calibration is generally acceptable, with the predicted hydrograph at Bromfleet matching well with the recorded flood timing. The predicted peak discharges at both Bromfleet and Wolffdene are much higher than the recorded peak. It is of note that the Wolffdene recorded hydrograph appears to be incomplete and the recorded peak at Broomfleet shows higher than the recoded peak at Wolffdene.

The February 1991 calibration for the Lower Logan is considered good. The predicted hydrograph at Macleans Bridge matches well with the recorded hydrograph with respect to peak discharges, volume, timing and shape of the hydrograph. Predicted peak discharges, timing and shape of the hydrograph at Waterford match well with the recorded data; however, the predicted peak discharge is higher than the recorded peak. It is likely that some flow bypasses the Waterford gauge via Pookgoor Creek and re-enters the Logan River downstream of the gauge.


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Gauging Station No

Stream Name

Peak Discharge

Recorded (m3/s)

Modelled (m3/s)







Waterford 040878 Lower Logan 892.0a 1282.0

a The recorded hydrograph does not include bypass flows to Pookgoor Creek.


The January 2008 flood can be considered a very small event in Teviot Brook and of moderate size in the Albert River and Upper and Lower Logan catchments.

In Teviot Brook, the calibration is generally good with regards to flood volume; however, the predicted flood peak at The Overflow is some 12 hours earlier and lower than the recorded flood peak. This is due to the small nature of the January 2008 flood, and the fact that the adopted channel lag parameter for Teviot Brook is based on larger floods and the whole Logan catchment. The January 2008 calibration in Teviot Brook can be improved by increasing the channel lag parameter for this event.

The Upper Logan calibration for the January 2008 event is acceptable, with predicted hydrographs at both Round Mountain and Yarrahappini matching well with recorded flood peak timing, peak discharges and volumes. Predicted peak discharges at both gauges are slightly high, and the predicted flood volumes slightly low.

The January 2008 Albert River calibration is generally good, with the predicted hydrograph at Bromfleet matching well with the recorded flood volume and time of flood peak. The predicted peak discharge at Bromfleet is marginally lower than the recorded peak. The predicted hydrograph at Wolffdene shows a significantly higher peak discharge than the recorded hydrograph. It is of note that recorded peak discharges at Bromfleet and Wolffdene are not consistent with one another (1065.2m3/s at Bromfleet and 715.2m3/s at Wolffdene). As such, matching the recorded Bromfleet hydrograph does not improve the calibration.

The January 2008 calibration for the Lower Logan is considered acceptable. The predicted hydrograph at Macleans Bridge matches satisfactorily with the recorded hydrograph in terms of peak discharge, shape and volume. Predicted peak discharges and volumes at Waterford are higher than the recorded data. The recorded data indicates significant attenuation or loss of


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volume between Macleans Bridge and Waterford, which is not reproduced by the model. Matching the Macleans Bridge recorded hydrograph only marginally improves the calibration at Waterford. It is likely that some flows bypass the Waterford gauge via Pookgoor Creek and re-enter the Logan River downstream of the gauge.





Gauging Station No

Stream Name

Peak Discharge

Recorded (m3/s)

Modelled (m3/s)

The Overflow 145012a Teviot Brook NA 621.0

Wyaralong Dam 540530 Teviot Brook 283.0a 543.0




Wolffdene 145196a Albert River 1174.0b 1339.0


Waterford 040878 Lower Logan 2088 2063.0 a the recorded hydrograph is incomplete and did not measure water level above 64.72m b estimated based on manual data


The January 2013 flood can be considered a moderate event in the whole Logan catchments.

In Teviot Brook, there are no recorded data available for The Overflow gauging station. The Wyaralong Dam gauging station did not measure water level above 64.72 m. However, model predicted excellent results up to the available recoded hydrograph (Figure 57).

The Upper Logan calibration for the January 2013 event is acceptable, with the predicted hydrograph timing and shape of the rising and falling limbs agreeing reasonably with the recorded hydrograph at Round Mountain. An excellent calibration result was achieved at Yarrahappini with respect to the predicted hydrograph peak discharge, volume and shape; however the peak discharge arrives earlier than the recorded flood peak.

The January 2013 Albert River calibration is acceptable, with the predicted hydrograph at Bromfleet matching well with the recorded flood peak and timing of rising limb. The predicted peak discharge at Bromfleet arrives approximately 12 hours earlier than the recorded peak discharge. The Wolffdene gauging station malfunctioned during the January 2013 event; however BOM provided manual peak recorded data. The model predicted slightly higher discharge than the manually recorded data.


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There are no data available for Macleans Bridge. The peak discharge at Waterford matches well, however the peak discharge arrives early and the volume of hydrograph slightly less than the recorded hydrograph.

7.7 Verification Results

7.7.1 May 1980 Event

A comparison of recorded and modelled peak discharges at key gauging stations for the May 1980 event are shown in Table 19. Verification hydrographs at all key gauging stations for the May 1980 event are provided in Appendix C (Section 16.6 ).

Table 19 - Modelled and recorded peak discharges at key gauging stations, May 1980 flood event


Gauging Station No

Stream Name

Peak Discharge

Recorded (m3/s)

Modelled (m3/s)








The following is of note with regards to the May 1980 verification:

The May 1980 flood can be considered a very small event in Teviot Brook, a small event in the Upper Logan and a moderate sized event in the Albert River and Lower Logan catchments.

At the Overflow the predicted flood peak is some 6 hours earlier and higher than the recorded flood peak. This is due to the small nature of the May 1980 flood, and the fact that the adopted parameters, initial and continuing losses are based on larger floods and whole Logan catchment. The May 1980 calibration in Teviot Brook can be improved by increasing the channel lag parameter for this event.

The Upper Logan verification for the May 1980 event is generally good, with the predicted hydrograph at Round Mountain returning a peak discharge and volume that matches well with the recorded hydrograph. The predicted hydrograph at Yarrahappini matches the recorded hydrograph adequately for flood peak, timing, volume and shape of hydrograph.

The May 1980 Albert River model verification is acceptable, with the predicted hydrograph at Bromfleet matching well with the recorded hydrograph in terms of shape and timing. The predicted peak discharge and flood volume are slightly higher than shown in the recorded hydrograph. The predicted flood volume is slightly lower than recorded flood volume at Wolffdene; however the peak discharge, shape and timing of the predicted hydrograph are very good.


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The May 1980 verification for the Lower Logan is considered acceptable. There are no data available for Macleans Bridge, and the entire flood hydrograph has not been recorded at Waterford. The recorded hydrograph at Waterford does not show the start or finish of the flood, although the peak discharge and a small section of the rising and falling limbs are shown. The predicted hydrograph does not accurately reproduce the recorded peak discharge or flood volume, and the timing of the predicted flood peak is some 12 hours late.

7.7.2 April 1988 Event

A comparison of recorded and modelled peak discharges at key gauging stations for the April 1988 event are shown in Table 20. Verification hydrographs at all key gauging stations for the April 1988 event are provided in Appendix C (Section 16.7 ).

Table 20 - Modelled and recorded peak discharges at key gauging stations, April 1988 flood event


Gauging Station No

Stream Name

Peak Discharge

Recorded (m3/s)

Modelled (m3/s)




Bromfleet 145102a Albert River 406.7a 476.6




a The recorded hydrograph appears to have failed to record the flood peak accurately.

The following is of note with regards to the April 1988 verification:

The April 1988 flood can be considered a moderately sized event in Teviot Brook, the Albert River and the Lower Logan catchments and a small event in the Upper Logan catchment.

In Teviot Brook, the verification is generally good, with the predicted hydrograph at the The Overflow matching well with the recorded hydrograph with regards to peak discharge and hydrograph shape, timing of first flood peak and volume. The timing of the predicted second flood peak is slightly early; this is due to the moderate nature of the April 1988 flood, and the fact that the adopted channel lag parameter is based on larger floods and whole Logan catchment.

The Upper Logan verification for the April 1988 event is good, with the predicted hydrograph at Round Mountain returning timing and volume that agree reasonably well with the recorded hydrograph, however the predicted flood peak is higher than the recorded flood peak. The predicted hydrograph at Yarrahappini matches the recorded hydrograph well with regards to peak discharge, hydrograph shape and timing. Predicted flood volumes at Yarrahappini are slightly higher than those shown in the recorded hydrograph.

The April 1988 Albert River model verification is acceptable. It appears that (due to inadequate rainfall coverage) early rainfall in the catchment has not been reproduced accurately in the model for the April 1988 event, as the predicted hydrograph at Bromfleet shows an initial flood


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peak that is not present in the recorded hydrograph. Further, it appears that the Bromfleet gauge may have malfunctioned during the April 1988 flood, as the recorded hydrograph appears to have been truncated during the initial flood peak. The predicted hydrograph at Wolffdene reproduces the recorded hydrograph peak discharge, shape and volume well.

The April 1988 verification for the Lower Logan is generally good. The predicted hydrograph at Macleans Bridge matches well with the recorded hydrograph with regards to shape, timing and volume. However the model predicted higher peak discharge than recorded peak discharge. The Waterford predicted hydrograph overestimates the peak discharge, and shows more attenuation than the recorded hydrograph.

7.7.3 March 2004 Event

A comparison of recorded and modelled peak discharges at key gauging stations for the March 2004 event are shown in Table 21. Verification hydrographs at all key gauging stations for the March 2004 event are provided in Appendix C (Section 16.8 ).

Table 21 - Modelled and recorded peak discharges at key gauging stations, March 2004 flood event


Gauging Station No

Stream Name

Peak Discharge

Recorded (m3/s)

Modelled (m3/s)








The following is of note with regards to the March 2004 verification:

The March 2004 flood can be considered a small sized event throughout the Logan catchment.

At The Overflow the predicted peak discharge is significantly higher than the recorded peak discharge. It appears that the gauge did not record the flood properly.

The Upper Logan verification for March 2004 is acceptable. The shape and timing of the hydrograph at Round Mountain are good; however, the model predicted lower peak discharge than recorded peak discharge. At Yarrahappini, the model predicted peak discharge, shape of hydrograph and volume is very good, however, the flood peak arrived slightly earlier that the recorded peak.

The March 2004 verification at Albert River is considered good, with the predicted hydrograph at Bromfleet matching well with the recorded hydrograph in terms of flood peak, timing, volume and shape. At Wolffdene, for this event, the flood volume is good; however, the model predicted a higher peak than the recorded peak.


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At Macleans Bridge, the predicted hydrograph matches well with the recorded hydrograph with respect to timing and shape of the hydrograph. However, the model predicted slightly higher peak discharge than the recorded peak. It appears that water level at Waterford was tidally influenced during this event. Therefore URBS model did not perform well at this gauging station.


A comparison of recorded and modelled peak discharges at key gauging stations for the January 2012 event are shown in Table 22. Verification hydrographs at all key gauging stations for the January 2012 event are provided in Appendix C (Section 16.9 ).



Gauging Station No

Stream Name

Peak Discharge

Recorded (m3/s)

Modelled (m3/s)

The Overflow 145012a Teviot Brook NA 49







The following is of note with regards to the January 2012 verification:

There are no recorded data available at The Overflow for this event. The Wyaralong Dam did not overflow during this event. The hydrographs at this station show a good match between the model prediction and the recorded stage hydrograph.

The January 2012 verification in the Upper Logan is acceptable. The predicted hydrograph rising limb and peak discharge at the Round Mountain is consistent with the recorded hydrograph. However, the model did not perform well at the falling limb, second and third peak. This was likely because of poor representation of rainfall. At Yarrahappini, the model generated an acceptable result in terms of hydrograph timing, peak discharge and volume.

The model did not produce good results at the Bromfleet gauging station. The reason might be poor representation of rainfall or/and datum issue at the station. The model underestimated flood and generated two peaks at Wolffdene, probably because of the same reason as was the case at Broomfleet (poor rainfall representation).

The January 2012 Lower Logan verification is acceptable, with the predicted hydrograph at the Macleans Bridge matching well with regards to timing, shape and volume; however, the predicted peak is slightly higher than the recorded peak discharge. The recorded water level at Waterford is tidally affected; however the timing of the predicted hydrograph peak matches well with the recorded peak discharge.


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8. Design Flood Estimation

The calibrated URBS model was used to estimate design flood discharges throughout the Logan River catchment based on design rainfall intensity - frequency – duration (IFD) data from a number of sources. Design flood discharge hydrographs were estimated for a range of storm durations up to 120 hours for the 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2000 ARI events, and for the PMPDF and PMF events.

8.1 Methodology

Based on a comprehensive review of available design rainfall data (IFD data, temporal patterns, areal reduction factors, rainfall spatial distribution and design rainfall losses), WRM (2008d) (Ref. 10) recommended the methodology for use in design event hydrology modelling for catchments in the City area. A number of modifications were made to the WRM (2008d) recommended methodology (Ref. 3) and is summarised in Table 23. The recommended methodology given in Table 23, Table 24 and Table 25 has been adopted for this study.


Table 23 - Summary of Recommended Methodology for Design Event Analysis

Design Flood Parameter

ARI Range (Years) Available Sources/Methods Comment Recommendation

Rainfall depth

≤ 100

ARR 1987 (Ref. 11) Industry standard approach. Not Recommended (Rainfall data till 1986)

AWE 1998 a (Ref. 12) or

AWE 1992 (Ref. 13)

Uses same methodology as ARR 1987 with additional data. AWE 1998 is recommended for Gold Coast catchments.

AWE 1992 is recommended for Logan River catchment.

Both methods use standard methodology with a longer period of recorded data.

Refer Table 24

CRCFORGE (Ref. 14) Based on analysis of daily data.

Adopted for Hinze Dam hydrology (HDA 2007) for events from 10 to 2000 year ARI (Ref. 29).

Recommended for storm durations ≥ 96 hours

Refer Table 24

BOM Pilot Study (Ref. 15) Data was provided by BoM for investigation of Hinze Dam hydrology, but it is no longer available.

Not Recommended

BOM 2013 New draft IFD was released by BOM in July 2013. The final IFD is expected to be released in 2015.

Not Recommended (Not finalised)

> 100 to 500

ARR 1987 Industry standard approach. Not Recommended

AWE 1998 a (Ref. 12) or

AWE 1992 (Ref. 13)

Uses same methodology as ARR 1987 with additional data. AWE 1998 is recommended for Gold Coast catchments.

AWE 1992 is recommended for Logan River catchment.

Refer Table 24.

CRCFORGE(Ref. 14) Based on analysis of daily data.

Adopted for Hinze Dam hydrology (HDA) for events from 10 to 2000 year ARI (Ref. 29).

Recommended for storm durations ≥ 96 hours

Refer Table 24

> 500 to <2000 Interpolate between ARI 500 (AWE) and ARI 2000 (CRCFORGE)

Creates a smoother transition between rainfall sources. Recommended for all storm durations, excluding storm durations ≥ 96 hours. Refer Table 24.

2000 CRCFORGE(Ref. 14) Based on analysis of daily data.

Adopted for Hinze Dam hydrology (HDA 2007) for events from 10 to 2000 year ARI Ref. 29).

Recommended.

Refer Table 24.

2,000 to < PMP Interpolate between CRCFORGE & PMP methods.

No explicit methodology is available to estimate rainfall depths for events of this magnitude.

Recommended.

Refer Table 24.




Section 3.6.3 of ARR 1999 provides a methodology for interpolation (Ref. 18).

PMP GSDM (≤ 6 hours)

GTSMR (> 24 hours)

Industry standard approach.

Linearly Interpolated for durations between 6 and 24 hours.

Recommended.

Refer Table 24.

Areal Reduction Factors

< 2000

ARR 1987 Based on United States data. Not Recommended

CRC ARF (Ref. 16 and Ref. 17) Derived from regional data for durations ≥ 24 hours. Recommended.

Adopt 24 hour duration ARFs for durations less than 24 hours.

Verify using flood frequency analysis where possible.

2,000 to < PMP Interpolate between CRCFORGE & PMP methods (Ref. 16 and Ref. 17).

Interpolate as recommended by ARR 1999 Section 3.6 using CRCFORGE and PMP rainfalls which are already factored for catchment area.

Recommended.


GTSMR (> 24 hours)

Industry standard approach. Recommended.

Temporal Pattern

≤ 100

ARR 1987 Industry standard approach. Not Recommended.

AWE 2000 Uses same methodology as ARR 1987 with additional data. Alternative patterns derived for ARI > 30 years (but only recommended for sensitivity analysis).

Not Recommended.

UWS 2006 Uses same methodology as ARR 1987 & AWE 2000 with additional data.

Not Recommended.

WRM v7 (Ref. 19) (≤ 72 hours)

GTSMR (≥ 96 hours)

AWE 2000 patterns have been filtered by WRM to eliminate sub-duration inconsistencies.

Industry standard approach.

Recommended

Use of filtered AWE 2000 patterns (≤ 72 hours) (Ref 19Error! Reference source not found.) and GTSMR (≥96 hours) recommended for Gold Coast and Logan Catchment.

Refer Table 25

> 100 to < PMP GSDM (≤ 6 hours)

GTSMR (> 24 hours)

Interpolate between WRM7 and GSDM or GTSMR.

PMP temporal patterns are recommended by ARR 1999 for this range of event magnitudes (Ref. 18).

Recommended.

Refer Table 25


GTSMR (> 24 hours)

Industry standard approach. Recommended.

Refer Table 25




Spatial Distribution

≤ 100 AWE 1998 a (Ref. 12) Estimate design rainfall at the centroid of each model sub-catchment and apply ARF based on whole catchment, as recommended in ARR 1987 (Ref. 11).

Recommended.

> 100 to 2000 CRCFORGE Estimate CRCFORGE rainfall at the centroid of each model sub-catchment.

Recommended.

> 2,000 to PMP GSDM (≤ 6 hours)

GTSMR (> 6 hours)

Adopt PMP spatial distribution for events greater than 2000 year ARI as recommended by ARR 1999 (Ref. 18).

Recommended.

Rainfall Losses

≤ 100

ARR 1987 (Ref. 11) Very little Queensland data used in recommended loss values for Queensland.

Suggests Initial losses in the range 15-35mm and a continuing loss rate of 2.5mm/hr.

Recommends adoption of median values from catchment-specific model calibration.

Not Recommended.

Ilahee 2005 (Ref. 20) Comprehensive study based on data for 48 Queensland catchments.

Estimated the median initial and continuing loss rates for eastern Queensland catchment to be 38mm and 1.52mm/hr respectively.

Recommended.

Adopt 38mm for initial loss and median continuing loss values from catchment specific model calibration.

> 100 to < PMP ARR 1999 (Ref. 18) Interpolate losses between 100 year ARI and PMP Design Flood using approach recommended by ARR 1999.

Recommended.

PMP ARR 1999 (Ref. 18) Adopt minimum values from catchment-specific model calibration, as recommended by ARR 1999.

Recommended.

a Includes IEAust 1987 Skewness


Table 24- Adopted Rainfall Depth (IFD) for Gold Coast Catchments.

Storm Duration

(hour)

ARI (Years)

1 2 5 10 20 50 100 200 500 1000 2000 PMP

0.5 INT AWE AWE AWE AWE AWE AWE AWE AWE INT CRC GSDM

1 INT AWE AWE AWE AWE AWE AWE AWE AWE INT CRC GSDM

1.5 INT AWE AWE AWE AWE AWE AWE AWE AWE INT INT GSDM


4.5 INT AWE AWE AWE AWE AWE AWE AWE AWE INT INT GSDM


9 INT AWE AWE AWE AWE AWE AWE AWE AWE INT INT INT

12 INT AWE AWE AWE AWE AWE AWE AWE AWE INT CRC INT

18 INT AWE AWE AWE AWE AWE AWE AWE AWE INT CRC INT

24 INT AWE AWE AWE AWE AWE AWE AWE AWE INT CRC GTSMR

36 INT AWE AWE AWE AWE AWE AWE AWE AWE INT INT GTSMR



96 INT INT CRC CRC CRC CRC CRC CRC CRC CRC CRC GTSMR

120 INT INT CRC CRC CRC CRC CRC CRC CRC CRC CRC GTSMR


Table 25 - Adopted Temporal Patterns for Gold Coast Catchments.

Storm Duration

(hour)

ARI (Years)

1 2 5 10 20 50 100 200 500 1000 2000 PMP

0.5 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 INT INT INT INT GSDM

1 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 INT INT INT INT GSDM





9 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 INT INT INT INT INT



24 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 WRMv7 INT INT INT INT GTSMR




96 GTSMR GTSMR GTSMR GTSMR GTSMR GTSMR GTSMR INT INT INT INT GTSMR

120 GTSMR GTSMR GTSMR GTSMR GTSMR GTSMR GTSMR INT INT INT INT GTSMR


Page 71 of 175

8.2 Rainfall Depth Estimation

8.2.1 Frequent to Large Design Events (up to and including 100 years ARI)

The adopted rainfall depth for the Logan River catchment is summarised in Table 24. Design rainfall intensities for storms of varying durations (10 minutes to 72 hours) for all ARI’s, up to and including the 100 Year ARI event, were determined at the centroid of each model sub-catchment using the methodology given in chapters 2 and 3 of IEAust (1987) (Ref. 11). The average rainfall intensities for each duration and ARI were then converted to total rainfall depths.

The input data for determination of design rainfall intensities for durations of up to 72 hours for all ARIs up to and including the 100 Year ARI event were as follows:

Rainfall intensity contours from Maps 1.5 to 4.5 from Volume 2 of IEAust (1987) (Ref. 11) for the 1 hour, 12 hour and 72 hour duration 2 Year ARI storms, and the 1 hour duration 50 Year ARI storm.

Rainfall intensity contours from Figures 4.12 and 4.13 from AWE (1992) for the 12 hour and 72 hour 50 Year ARI storms. These contours replaced Maps 1.5 to 4.5 from Volume 2 of IEAust (1987) in the eastern part of the Logan River catchment, including the Albert River catchment.

F2 and F50 factor contours from Maps 8 and 9, Volume 2 of IEAust (1987).

Skewness contours from Map 7c, Volume 2 of IEAust (1987).

Rainfall contours covering the City area only for the 1, 12 and 72 hour duration 2 Year and 50 Year storms, and F2 and F50 factor contours as given in AWE’s Review of Gold Coast Rainfall Data study (AWE,1998). These contours replaced Maps 1.5 to 4.5 and Maps 8 and 9 from Volume 2 of IEAust (1987) in the City area only.

The 96 and 120 hour duration rainfall intensities and depths for all ARI’s up to 100 Years were obtained for a number of representative locations throughout the modelled catchments using the CRCForge Rainfall estimation program (Hargaves, 2004). The adopted representative locations were selected based on the adopted 72 hour 100 Year ARI rainfall gradients, with each location representing an area of sub-catchments with similar rainfall depths. Two representative locations were selected in each of the Teviot Brook, Albert River and Lower Logan River catchments, and four representative locations were selected in the Upper Logan River catchment. The selected locations are as follows:

Centroids of Teviot Brook sub-catchments 5 and 23.

Centroids of Albert River sub-catchments 419 and 430.

Centroids of Upper Logan sub-catchments 133, 138, 171 and 188.

Centroids of Lower Logan sub-catchments 317 and 349.

The 96 and 120 hour rainfall depth for each representative location was applied to all sub-catchments associated with that location (i.e. in areas of similar 72 hour 100 Year ARI rainfall depth). As such, a number of sub-catchments in each model have identical rainfall depths for the 96 hour duration storms. The representative locations assigned to each model sub-catchments are described below:

96 and 120 hour rainfalls estimated at the centroid of (Teviot Brook) sub-catchment 5 were applied to:


Page 72 of 175

o Sub-catchments 1 to 16.

96 and 120 hour rainfalls estimated at the centroid of (Teviot Brook) sub-catchment 23 were applied to:

o Sub-catchments 17 to 32.

96 and 120 hour rainfalls estimated at the centroid of (Albert River) sub-catchment 419 were applied to:

o Sub-catchments 407 to 423 and 438 to 441.

96 and 120 hour rainfalls estimated at the centroid of (Albert River) sub-catchment 430 were applied to:

o Sub-catchments 401 to 406, 424 to 437 and 442 to 448.

96 and 120 hour rainfalls estimated at the centroid of (Upper Logan) sub-catchment 133 were applied to:

o Sub-catchments 101 to 106, 111 to 218, 122 to 127, 129 to 135 and 143 to 150.


o Sub-catchments 107 to 110, 119 to 121, 128, 136 to 142, and 151 to 163.


o Sub-catchments 164 to 172, 175, 179 to 186 and 189.


o Sub-catchments 173 and 174, 176 to 178, 187 and 188, and 190 to 203.

96 and 120 hour rainfalls estimated at the centroid of (Lower Logan) sub-catchment 317 were applied to:

o Sub-catchments 301 to 319 and 322 to 330.

96 and 120 hour rainfalls estimated at the centroid of (Lower Logan) sub-catchment 349 were applied to:

o Sub-catchments 320 and 321, and 331 to 368.

8.2.2 Rare to Extreme Design Events (200 to 2000 years ARI)

Table 24 shows details of rainfall used in this study. Design rainfall depths for the 200, 500 and 2000 Year ARI events were estimated as follows:

Design rainfall depths for durations of between 10 minutes and 72 hours for the 200 and 500 Year ARI events were estimated at the representative locations discussed in Section 8.2.1 using the methodology described in chapters 2 and 3 of IEAust (1987) (Ref. 11) and the input data described in Section 8.2.1 .


Page 73 of 175

Design rainfall depths for durations from 96 to 120 hours for the 200 and 500 Year ARI events were estimated at the representative locations discussed in Section 8.2.1 using the CRCForge rainfall application (Hargraves, c.2004 – Ref. 14).

Design rainfall depths for all durations for the 2000 Year ARI event were estimated at the representative locations discussed in Section 8.2.1 using the CRCForge rainfall application, as recommended in Table 23.

No areal reduction factors were applied (for any ARI) when extracting the rainfalls from the CRCForge rainfall application.

Design rainfall depths for all durations for the 1000 Year ARI event were estimated at each centroid by interpolating between the 500 year ARI (AWE 1992) and 2000 year ARI (CRCForge data).

The adopted design rainfall depths for the Logan River catchment are summarised in Table 24.

8.2.3 Probable Maximum Precipitation Design Flood (PMPDF)

PMP rainfall depths were estimated as follows:

PMP rainfall depths for durations from 12 hours to 120 hours were estimated using the standard methodology given in the ‘Generalised Tropical Storm Method (GTSMR) – Revised Edition’ (BOM, 2003b – Ref. 22), based on the total catchment area of the Logan River. The Topographic Adjustment Factor at the centroid of each model sub-catchment was used to obtain the individual sub-catchment PMP estimates from the overall catchment PMP estimate.

PMP rainfall depth estimates for shorter durations would normally be obtained using the methodology given in the ‘Estimation of Probable Maximum Precipitation in Australia: Generalised Short Duration Method’ (BOM, 2003a – Ref. 21), however the size of the Logan River catchment (>1000km2) invalidates the use of this method. As such PMP rainfalls were only obtained for durations greater than 12 hours. The notional AEP of the estimated PMP design flood is 1 in 263,000 (BOM, 2003a).

8.2.4 Probable Maximum Flood (PMF)

PMP rainfalls were applied for estimation of PMF discharges and rainfall depths were obtained as described section 8.2.3 .

8.3 Temporal Patterns


Temporal patterns for design storm events for durations from 30 minutes to 72 hours for design events up to and including 100 Years ARI were adopted from filtered AWE 2000 (Ref. 23) Temporal Patterns as outlined in WRM 2008b report (Ref. 19).

The temporal pattern for the 96 to 120 hour durations are sourced from the ‘Generalised Tropical Storm Method (GTSMR) – Revised Edition’ (BOM, 2003b – Ref. 22).

The adopted temporal patterns are given in Table 25 and Appendix D (Section 17).


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Temporal patterns for the 200, 500, 1000 and 2000 Year ARI design storms for durations from 30 minutes to 72 hours were linearly interpolated between the 100 year ARI temporal pattern (section 8.3.1 and the PMP temporal pattern (section 8.3.3 ).

The temporal pattern for the 96 to 120 hour durations were obtained from the ‘Generalised Tropical Storm Method (GTSMR) – Revised Edition’ (BOM, 2003b – Ref. 22).


Temporal patterns for the PMP design storms were obtained as follows:

The temporal pattern for the 12 hour duration PMP event was obtained from The Estimation of Probable Maximum Precipitation in Australia: Generalised Short Duration Method (BOM 2003a, Ref. 21);

Temporal patterns for the PMP event for durations from 18 hours to 120 hours were obtained for the Coastal AVM storms from the Generalised Tropical Storm Method – Revised Edition (BOM, 2003b – Ref. 22). The temporal pattern for 18 hours was generated by interpolating from the 24 hour pattern.

Temporal patterns for the 96 and 120 hour PMF events for the designated Coastal Storms were obtained from the Generalised Tropical Storm Method – Revised Edition (BOM, 2003b, Ref. 22).

The adopted temporal patterns are given in Table 25 and Appendix D (Section 17).


Temporal patterns for durations from 24 hours to 120 hours for the top ten individual storms were obtained from ‘The Coastal Storms from the Generalised Tropical Storm Method – Revised Edition’ ((BOM, 2003b – Ref. 22). Table 26 shows historical temporal patterns used in this study.

Table 26 - Ten Historical Temporal Patterns used for PMF

24 hours 36 hours 48 hours 72 hours 96 hours 120 hours

PMF01 1893FEB03-1 1893FEB03-2 1893FEB03-2 1918JAN25-5 1918JAN25-5 1918JAN25-5

PMF02 1898APR03-2 1898APR03-2 1918JAN24-3 1972JAN12-5 1972JAN12-5 1972JAN12-5

PMF03 1954FEB21-2 1954FEB21-2 1963APR16-4 1974JAN23-6 1974JAN23-6 1974JAN23-6

PMF04 1955FEB25-2 1955FEB25-2 1972JAN12-5 1974JAN28-4 1974JAN28-4 1974JAN27-9

PMF05 1956JAN22-2 1963APR16-4 1974JAN09-3 1974MAR13-4 1974MAR13-4 1975FEB25-6

PMF06 1963APR16-4 1974JAN28-4 1974JAN27-2 1979JAN06-4 1979JAN06-5 1979JAN06-5

PMF07 1974MAR13-4 1974MAR13-4 1975DEC10-2 1995FEB28-4 1991JAN01-7 1991JAN01-7

PMF08 1976FEB09-2 1982JAN22-2 1978JAN30-5 1997MAR06-7 1997MAR06-7 1996MAR10-7


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24 hours 36 hours 48 hours 72 hours 96 hours 120 hours

PMF09 1982JAN20-5 1989MAR14-2 1982JAN22-2 1998JAN29-4 1998JAN29-4 1997MAR06-7

PMF10 1989MAR14-2 1995FEB28-4 1995FEB28-4 1998MAR05-7 1998MAR05-7 1998MAR05-7

8.4 Areal Reduction Factors


The Queensland Extreme Rainfall Estimation Project (EREP) (Hargraves c.2004 – Ref. 16) developed the following relationship between ARF, catchment area and storm duration for Queensland catchments:

ARF = 1 – 0.226 x (Area0.1685 – 0.8306 x log (Duration)) x Duration-0.3994

Where

ARF = Areal reduction factor

Area = Catchment area (km2)

Duration = Rainfall duration (hours)

Table 27 shows the adopted areal reduction factors (ARFs) for design rainfalls for all durations and ARIs. ARFs calculated based on the total Logan River catchment area for 24, 36, 48, 72, 96 and 120 hour storm durations were initially applied to design rainfall depths for all ARI’s. The 24 hour ARF was applied for all durations shorter than 24 hours, as recommended in Table 23.

However in order to reconcile the URBS model design event results with flood frequency discharge estimates it was necessary to revise the approach to assigning ARFs. ARFs calculated based on the catchment sizes upstream of individual gauging stations were adopted for each catchment, and the 24 hour ARF was applied for all durations less than 24 hours.

Table 27 - Adopted Areal Reduction Factors

Storm Duration

(Hours)

Areal Reduction Factor (ARF)

based on Total Catchment Area

(3878 km2)

24 and less 0.82

36 0.85

48 0.87

72 0.90

96 0.91

120 0.92


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Areal reduction factors were applied to the 200, 500, 1000 and 2000 Year ARI design rainfalls as described in section 8.4.1 .


As aerial reduction factors are incorporated in the PMP rainfall estimation methodology (BoM 2003a – Ref. 21 and BoM 2003b – Ref. 22), no additional ARFs were applied to the rainfalls estimated for the catchment using this method.


No additional ARF were applied as described in section 8.4.3 .

8.5 Rainfall Losses


The initial loss (IL) and continuing loss (CL) method of accounting for rainfall losses was adopted for this study. The URBS model design event ILs and CLs were adjusted to align the design output discharges with the Flood Frequency Analysis (FFA) discharges. Table 28 shows the final ILs and CLs for the Logan River catchment for all ARIs up to and including the 100 year ARI event.

Table 28 - Adopted Initial Loss and Continuing Loss, 2 to 100 Year ARI Events

ARI (Years)

Adopted Losses

Initial Loss (mm) Continuing Loss (mm/hour)

2 20 3.0

5 15 2.0

10 10 1.2

20 0 0.8

50 0 0.4

100 0 0.1


An initial loss (IL) of 0.0 mm was adopted for 100 year ARI event (refer section 8.5.1 ). Therefore, it was considered appropriate to adopt the same IL for all events from 200 to 2000 100 year ARI. For the same reason, a CL of 0.1 mm/hour (refer section 8.5.1 ) was adopted for the all events from 200 to 2000 years ARI.


As recommended in Table 23 and for reasons given in section 8.5.2 , an initial loss 0.0 mm and a 0.1 mm/hour continuing loss rate were adopted for the PMP design flood event.


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The initial loss and continuing loss rate adopted for PMPDF (IL = 0.0 mm and CL = 0.1 mm/hr) were adopted for the PMF event.

8.6 Spatial Distribution


The design rainfalls for durations from 30 minutes to 72 hours for all ARIs up to and including 100 Years were estimated at the centroid of each model sub-catchment using standard IEAust (1987) (Ref. 11) procedures, which incorporates spatial variation in design rainfalls based on the input design rainfall and factor contours. This is in accordance with the methodology described in Table 23. The 96 and 120 hour duration rainfalls for ARIs up to and including 100 Years were estimated using the CRCForge rainfall application (Hargraves, c.2004 – Ref. 14) at a number of representative locations throughout the modelled catchments. This method accounts for spatial variation in rainfalls throughout a catchment, as the representative locations were selected based on the adopted 72 hour 100 Year ARI rainfall gradients, with each location representing an area of sub-catchments with similar rainfall depths.


Spatial variation in design rainfalls was taken into account by using design rainfalls for durations from 30 minutes to 120 hours for all ARIs between 200 and 2000 years (inclusive) at the centroid of each model sub-catchment as described in section 8.2.2 . This is in accordance with the methodology described in Table 23.


Spatial distribution of rainfall is accounted for in the Generalised Tropical Storm Method – Revised Edition (BOM, 2003b – Ref. 22) for PMP rainfall depth estimation methodology.


Spatial distribution of rainfall is accounted for in the PMP estimation methodology (section 8.6.3 ).

8.7 Design Discharges


Table 29 and Table 30 show the URBS model predicted design discharges and critical storm durations respectively for the 2, 5, 10, 20, 50 and 100 year ARI events at key locations throughout the Logan River catchment. Design event hydrographs (for the critical storm duration) at key locations are shown in Appendix E (Section 18). It is noted that all the design discharge estimates are based on the application of the ARF for the total Logan River catchment area.


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Table 29 - URBS Model Predicted Design Discharges, 2 to 100 year ARI events

Location

(Gauging

Station)

Stream Name

Peak Design Discharge (m3/s)

2 Year

ARI

5 Year

ARI

10 Year

ARI

20 Year

ARI

50 Year

ARI

100 Year

ARI

Croftby Teviot Brook 34 90 138 199 263 317

Boonah Teviot Brook 129 301 447 626 807 955

The Overflow

Teviot Brook 169 379 592 819 1077 1288

Forest Home Logan River 60 167 258 377 488 577

Rathdowney Logan River 184 466 702 1008 1306 1546

Dieckmans Bridge

Running Creek

86 180 253 342 432 503

Rudds Lane Christmas

Creek 121 240 332 446 559 649

Round Mountain

Logan River 473 1053 1572 2176 2817 3350

Beaudesert Logan River 451 1013 1591 2178 2888 3443

Yarrahappini Logan River 512 1228 2062 2890 3918 4752

Macleans Bridge

Logan River 488 1114 1884 2627 3520 4205

Waterford Logan River 454 1047 1801 2549 3423 4096

First Ave Scrubby Creek

66 125 168 220 274 317

Reserve Park

Slacks Creek

40 67 85 111 134 153

Loganlea Slacks Creek

87 157 213 280 350 406

Eagleby Logan River 449 1038 1787 2536 3408 4078

Lumeah #2 Albert River 113 235 329 440 554 647

Benobble Canungra

Creek 71 166 241 328 426 506

Bromfleet Albert River 282 669 997 1328 1720 2036

Wolffdene Albert River 321 801 1214 1612 2111 2503

Beenleigh Albert River 323 815 1241 1652 2164 2569

Riedel Road Logan River 500 1281 1979 2768 3837 4682

Logan River Mouth

Logan River 504 1306 2042 2831 3840 4709


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Table 30 - URBS Model Predicted Critical Storm Durations, 2 to 100 year ARI events

Location

(Gauging

Station)

Stream Name

Critical Storm Duration (hours)

2 Year

ARI

5 Year

ARI

10 Year

ARI

20 Year

ARI

50 Year

ARI

100 Year

ARI

Croftby Teviot Brook 9 9 9 9 9 9

Boonah Teviot Brook 9 9 12 9 12 12

The Overflow

Teviot Brook 9 9 36 18 36 36

Forest Home Logan River 9 9 9 6 6 6

Rathdowney Logan River 9 9 9 9 9 9

Dieckmans Bridge

Running Creek

9 9 9 6 9 9


Creek 9 9 9 9 9 9

Round Mountain

Logan River 9 12 18 12 36 36

Beaudesert Logan River 9 18 36 36 36 36

Yarrahappini Logan River 9 18 36 36 48 48

Macleans Bridge

Logan River 9 18 36 48 48 48

Waterford Logan River 9 18 36 48 48 48


9 9 9 9 9 9

Reserve Park

Slacks Creek

3 3 3 3 3 3


9 12 12 12 12 12

Eagleby Logan River 9 18 36 48 48 48

Lumeah #2 Albert River 12 12 12 12 12 12

Benobble Canungra

Creek 12 12 36 12 12 12

Bromfleet Albert River 12 18 36 18 36 36

Wolffdene Albert River 12 36 36 36 36 36

Beenleigh Albert River 12 36 36 36 36 36

Riedel Road Logan River 9 36 36 72 72 72

Logan River Mouth

Logan River 9 36 48 48 72 96


Page 80 of 175


Table 31 and Table 32 show the URBS model predicted design discharges and critical storm durations for the 200, 500, 1000 and 2000 year ARI events at key locations throughout the Logan River catchment. Design event hydrographs (for the critical storm duration) at key locations are shown in Appendix E (Section 18). It is noted that all the design discharge estimates are based on the application of the ARF for the total Logan River catchment area.

Table 31 - URBS Model Predicted Design Discharges, 200 to 2000 year ARI events

Location

(Gauging

Station)

Stream Name

Peak Design Discharge (m3/s)

200 Year

ARI

500 Year

ARI

1000 Year

ARI

2000 Year

ARI

Croftby Teviot Brook 366 437 440 443

Boonah Teviot Brook 1084 1268 1382 1526

The Overflow

Teviot Brook 1453 1681 1878 2102

Forest Home Logan River 659 775 869 978

Rathdowney Logan River 1757 2056 2293 2561

Dieckmans Bridge

Running Creek

562 646 701 767


Creek 725 831 859 923

Round Mountain

Logan River 3747 4287 4826 5471

Beaudesert Logan River 3859 4428 5025 5739

Yarrahappini Logan River 5273 6071 6927 7938

Macleans Bridge

Logan River 4650 5251 6000 6879

Waterford Logan River 4537 5137 5922 6872


356 410 469 535

Reserve Park

Slacks Creek

172 198 219 243


456 526 584 664

Eagleby Logan River 4519 5166 5965 6933

Lumeah #2 Albert River 728 841 903 1042

Benobble Canungra

Creek 580 684 651 645

Bromfleet Albert River 2295 2674 2910 3244

Wolffdene Albert River 2826 3271 3616 4029

Beenleigh Albert River 2905 3369 3726 4150

Riedel Road Logan River 5342 6394 7281 8284

Logan River Mouth

Logan River 5422 6492 7393 8409


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Table 32 - URBS Model Predicted Critical Storm Durations, 200 to 2000 year ARI events

Location

(Gauging

Station)

Stream Name

Critical Storm Duration (hours)

200 Year

ARI

500 Year

ARI

1000 Year

ARI

2000 Year

ARI

Croftby Teviot Brook 9 9 9 6

Boonah Teviot Brook 12 12 12 9

The Overflow

Teviot Brook 36 36 36 36

Forest Home Logan River 6 6 6 6

Rathdowney Logan River 9 9 9 9

Dieckmans Bridge

Running Creek

9 6 6 6


Creek 9 9 9 6

Round Mountain

Logan River 36 36 36 36

Beaudesert Logan River 36 36 36 36

Yarrahappini Logan River 48 36 36 36

Macleans Bridge


Waterford Logan River 48 72 72 72


9 9 9 9

Reserve Park

Slacks Creek

3 3 3 3


12 12 12 36

Eagleby Logan River 48 72 72 72

Lumeah #2 Albert River 12 12 36 36

Benobble Canungra

Creek 12 12 36 36

Bromfleet Albert River 18 18 36 36

Wolffdene Albert River 36 36 36 36

Beenleigh Albert River 36 36 36 36

Riedel Road Logan River 96 96 96 72

Logan River Mouth



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Table 33 shows the URBS model predicted peak PMP Design Flood (PMPDF) discharges and critical durations at key locations throughout the Logan River catchment. Design event hydrographs (for the critical storm duration) at key locations are shown in Appendix E (Section 18). To estimate PMPDF discharges, the URBS model was run for all storm durations from 12 hours to 120 hours.

Table 33 - URBS Model Predicted Design Discharges and critical storm duration, PMPDF event

Location

(Gauging

Station

Stream Name PMPDF Discharge

(m3/s)

PMPDF Critical

Duration (hours)

Croftby Teviot Brook 1767 12

Boonah Teviot Brook 5040 12

The Overflow

Teviot Brook 6060 12

Forest Home Logan River 2698 12

Rathdowney Logan River 7694 12

Dieckmans Bridge

Running Creek

2182 12


Creek 2719 12

Round Mountain

Logan River 15168 12

Beaudesert Logan River 14388 12

Yarrahappini Logan River 18238 24

Macleans Bridge


Waterford Logan River 13440 72


1109 12

Reserve Park

Slacks Creek

440 12


1496 12

Eagleby Logan River 13901 120

Lumeah #2 Albert River 2547 12

Benobble Canungra

Creek 1794 12

Bromfleet Albert River 7092 12

Wolffdene Albert River 7919 12

Beenleigh Albert River 7924 12

Riedel Road Logan River 17450 120

Logan River Mouth



Page 83 of 175


Table 34 shows the URBS model predicted peak PMF discharges and critical durations at key locations throughout the Logan River catchment. Design event hydrographs (for the critical storm duration) at key locations are shown in Appendix E (Section 18). To estimate PMF discharges, the URBS model was run for the storm durations from 24 hours to 72 hours for the top ten individual storm temporal patterns.

Table 34 - URBS Model Predicted Design Discharges and critical storm duration, PMF events

Location

(Gauging

Station

Stream Name PMF Discharge

(m3/s)

PMF Critical

Duration

(hours)

Critical PMF

Storm Temporal

Pattern

Croftby Teviot Brook 1822 24 1982JAN20-5

Boonah Teviot Brook 4835 24 1982JAN20-5

The Overflow

Teviot Brook 5938 24 1982JAN20-5

Forest Home Logan River 2966 24 1982JAN20-5

Rathdowney Logan River 7768 24 1976FEB09-2

Dieckmans Bridge

Running Creek

2371 24 1982JAN20-5


Creek 2837 24 1982JAN20-5

Round Mountain

Logan River 14844 24 1982JAN20-5

Beaudesert Logan River 14684 24 1982JAN20-5

Yarrahappini Logan River 19915 36 1954FEB21-2

Macleans Bridge

Logan River 14193 36 1954FEB21-2

Waterford Logan River 14290 96 1974JAN28-4


1072 24 1982JAN20-5

Reserve Park

Slacks Creek

490 24 1982JAN20-5


1490 24 1976FEB09-2

Eagleby Logan River 14793 96 1998MAR05-7

Lumeah #2 Albert River 2442 24 1982JAN20-5

Benobble Canungra

Creek 1748 24 1982JAN20-5

Bromfleet Albert River 6872 24 1976FEB09-2

Wolffdene Albert River 8137 36 1954FEB21-2

Beenleigh Albert River 8358 36 1954FEB21-2

Riedel Road Logan River 18505 72 1995FEB28-4

Logan River Mouth

Logan River 18617 96 1974MAR13-4


Page 84 of 175

8.7.5 Comparison with Previous Studies

Table 35, Table 36 and Table 37 compare the estimated peak design discharges from this study with the peak design discharges reported in the Sunwater (2007), AWE (1997) and WRM (2009) studies. The following is of note:

The result comparisons are based on ARF’s applied to each gauging station rather than the ARF for the total Logan River catchment. Therefore, the design discharges shown in tables Table 35, Table 36 and Table 37 are higher than the equivalent discharges shown in Table 29 and Table 31.

The URBS model estimated peak design discharges for Teviot Brook at The Overflow match closely with the estimates given by the Sunwater (2007) and WRM (2009) study for all ARIs up to and including the 2000 Year ARI event.

The URBS model estimated peak design discharges at Bromfleet, Wolffdene and Beenleigh match the AWE (1997) estimated peak discharges reasonably, however the URSB model estimated peak discharges at these stations are higher than those estimated by the WRM (2009) study. This is likely due to differences in adopted design rainfalls and temporal patterns between the WRM (2009) and current study. The adopted rating curve at Wolffdene also differs substantially between the current study and the AWE (1997) study. It is also noted that an additional model (forest factor) parameter and a single set of model parameters were used for the whole Logan catchment in this study.

The URBS model estimated peak design discharges at Yarrahappini match the AWE (1997) estimated peak discharges well and are higher than the WRM (2009) study. The URBS model estimated discharges at Waterford are lower than those estimated by the AWE (1997) study. The calibration and verification events selected for this study indicated that significant attenuation of flows in the Logan River occurs between Yarrahappini and Waterford (WRM 2009, Ref. 2). The URBS model developed for this study was configured to reproduce this attenuation as best as possible. The AWE (1997) study was not calibrated at Waterford, and as such no such attenuation is evident in the results from that study. The AWE (1997) study did not apply ARFs to design rainfalls.

The current study had 10 more years of data available for use in FFA. This enabled an updated FFA to be produced, with more certainty attached to discharge estimations for events up to 20 Years ARI. Further, FFA was undertaken at more locations than the AWE (1997) study, providing more locations to reconcile URBS model design event results with the updated FFA discharge estimates.

The current study calibrated the model to two additional recent flood events (January 2012 and January 2013) and used an additional model parameter (forest factor) than did the WRM (2009) study, along with some modification of methodologies.


Page 85 of 175

Table 35 - Comparison of estimated peak design discharges at The Overflow, Teviot Brook

ARI (years)


Sunwater

(2007) WRM (2009) Current study

2 170 127 208.9

5 430 395 440

10 630 645 665.6

20 830 903 909.3

50 1100 1097 1182.7

100 1300 1258 1403.9

200 1500 1439 1580

500 1800 1690 1826.7

2000 2200 2171 2268.8

Table 36 - Comparison of design discharges estimated by current and previous studies, Albert River

ARI

(years)

Estimated Design Discharge (m3/s)

Bromfleet Wolffdene Beenleigh

AWE

(1997)

WRM

(2009) Current

AWE

(1997)

WRM

(2009) Current

AWE

(1997)

WRM

(2009) Current

10 970 1111 1094 1185 1133 1313 1229 1155 1339

20 1322 1358 1465 1614 1390 1738 1672 1418 1770

50 1891 1688 1877 2303 1724 2254 2382 1757 2307

100 2373 1959 2213 2886 2008 2667 2984 2045 2733

Table 37 - Comparison of design discharges estimated by current and previous studies, Logan River

ARI

(years)

Estimated Design Discharge (m3/s)

Yarrahappini Waterford

AWE

(1997)

WRM

(2009) Current

AWE

(1997)

WRM

(2009) Current

10 2211 2050 2122 2248 1891 1837

20 2978 2489 2960 3031 2276 2586

50 3990 3049 3994 4052 2782 3467

100 4832 3503 4838 4905 3176 4145


Page 86 of 175

9. Flood Frequency Analysis

9.1 Method of Analysis

Design Flood discharges were estimated by flood frequency analysis (FFA) using all available height data and the adopted rating curves (Refer Section 5.6 ). The following gauges were selected for FFA due to their key locations within the catchment and length (over 30 years) of historical record:

Teviot Brook at The Overflow (DNRM GS 145012a).

Logan River at Round Mountain (DNRM GS 145008a).

Logan River at Yarrahappini (DNRM GS 145014a).

Albert River at Bromfleet (DNRM GS 145102b).


The methodology recommended in Australian Rainfall and Runoff (IEAust, 1987 – Ref. 11) was used to fit a Log-Pearson Type III distribution to an annual series of recorded peak flood discharges at these locations.

9.2 Available data

9.2.1 Peak Annual Data

The peak annual gauge heights and discharges recorded at the selected gauge sites were obtained from the DNRM website. The peak annual discharges at each gauge were estimated from peak recorded flood heights using the rating curves adopted for this study. A summary of the available peak series data for each gauge is given in Table 38. The following is of note with regards to Table 38:

The annual data is presented for standard calendar years (i.e. January – December).

No recorded annual peak series data was available for The Overflow for 1973, 1977, 1979, 1986, 1993, 2000, 2005, 2007, 2012 and 2013.

No recorded annual peak series data was available for Round Mountain for 1960, 1966, 1973, 1977, 1979, 1985, 2000, 2002, 2005 and 2007.

No recorded annual peak series data was available for Yarrahappini for 1973, 1975, 1984, 1993, 2000, 2002, 2005 and 2007.

No recorded annual peak series data was available for Bromfleet for 1924, 1926, 1932, 1936, 1944, 1957, 1960, 1962, 1964, 1975, 1982, 2002 and 2007.

No recorded annual peak series data was available for Wolffdene for 1977, 1982, 1987, 1993, 1997, 2000, 2005, 2006 and 2007.


Page 87 of 175

Table 38 - Summary of annual peak series data

Gauging

Station Name

Gauging

Station No Stream Name Period of Gauge

Record

Years Without

Record

Years of

Available Data

The Overflow 145012a Teviot Brook 1967 - 2013 10 36

Round Mountain

145008a Upper Logan 1958 - 2013 10 43

Yarrahappini 145014a Upper Logan 1969 - 2013 8 34

Bromfleet 145102a Albert River 1920 - 2013 13 78

Wolffdene 145196a Albert River 1969 - 2013 9 33

9.2.2 Other Historical Data

No historical flood data (pre-dating the period of record) was available at any of the selected gauge sites for the study. It is of note that FFA undertaken for Yarrahappini, Bromfleet and Wolffdene in the AWE (1997) study included some historical data; however this data was not available for use in this study.

9.3 Analysis and Results

The standard method of frequency analysis, as described in Book 4, Section 2 of Australian Rainfall and Runoff (IEAust, 1987 – Ref. 11) was used to estimate peak flood discharges for various Annual Exceedance Probabilities (AEP’s) at the selected gauge sites. A Log Pearson Type III Distribution was fitted to the discharge data for the five selected gauging stations. The flood frequency distributions for each gauge are given in following sections.

9.3.1 The Overflow

Figure 12 and Table 39 show the plot of the fitted flood frequency distribution and the FFA estimated design peak discharges respectively at The Overflow. The FFA analysis is based on 36 years recorded data and three low flows were omitted from the analysis.


Page 88 of 175

Figure 12: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Teviot

Brook at The Overflow (145012a)

Table 39 - Flood Frequency Analysis Results, Teviot Brook at the Overflow (145012a)

ARI (Years) Estimated Peak Discharge (m3/s)

95% Confidence Limit Adopted Value 5% Confidence Limit

2 51 86 146

5 222 336 510

10 378 566 847

20 496 815 1337

50 566 1159 2372

100 570 1421 3543


Page 89 of 175

9.3.2 Round Mountain

Figure 13 and Table 40 show the plot of the fitted flood frequency distribution and the FFA estimated design peak discharges respectively at Round Mountain. The analysis is based on 43 years recorded data and one low flow was omitted from the analysis.

Figure 13: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Logan

River at Round Mountain (145008a)

Table 40 - Flood Frequency Analysis Results, Logan River at Round Mountain (145008a)



2 290 453 537

5 758 1083 1151

10 1079 1560 1691

20 1260 2023 2318

50 1314 2606 2971

100 1274 3018 3515


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9.3.3 Yarrahappini

Figure 14 and Table 41 show the plot of the fitted flood frequency distribution and the FFA estimated design peak discharges respectively at Yarrahappini. The analysis is based on 34 years recorded data and nineteen low flows were omitted from the analysis.

Figure 14: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Logan

River at Yarrahappini (145014a)

Table 41 - Flood Frequency Analysis Results, Logan River at Yarrahappini (145014a)



2 227 572 1441

5 781 1092 1528

10 1053 1580 2371

20 1280 2212 3824

50 1296 3369 8761

100 1108 4579 18919


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9.3.4 Bromfleet

Figure 15 and Table 42 show the plot of the fitted flood frequency distribution and the FFA estimated design peak discharges respectively at Bromfleet. The analysis is based on 78 years recorded data and six low flows were omitted from the analysis.

Figure 15: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Albert

River at Bromfleet (145102b)

Table 42 - Flood Frequency Analysis Results, Albert River at Bromfleet (145102b)



2 207 286 394

5 493 672 915

10 703 985 1380

20 888 1325 1978

50 1076 1819 3074

100 1177 2227 4212


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9.3.5 Wolffdene

Figure 16 and Table 43 show the plot of the fitted flood frequency distribution and the FFA estimated design peak discharges respectively at Wolffdene. The analysis is based on 33 years recorded data and three low flows were omitted from the analysis.

Figure 16: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Albert

River at Wolffdene

Table 43 - Flood Frequency Analysis Results, Albert River at Wolffdene (145196a)



2 90 164 298

5 404 652 1053

10 670 1067 1699

20 885 1511 2580

50 1022 2131 4441

100 1034 2615 6615


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9.4 Comparison with URBS Results

Table 44 to Table 46 compare the URBS model estimated peak design discharges at The Overflow, Round Mountain, Yarrahappini, Bromfleet and Wolffdene with the peak discharge estimates obtained from the FFA. Figure 12 to Figure 16 show the URBS model peak design discharges plotted against the adopted flood frequency distribution curves and recorded peak series data at each location. The following is of note:

The design peak discharges estimated by the URBS model for Teviot Brook at The Overflow correspond well to the flood frequency discharge estimates for the 20 Year ARI up to the 100 Year ARI. For ARIs less than 20 Years the URBS model discharge estimates are higher than those predicted by the FFA; however the URBS model discharge estimates are well within the flood frequency confidence limits 5 and 10 Year ARIs. Further to this, the URBS model results match discharges predicted by the Sunwater (2007) Teviot Brook URBS model for all ARIs except 2 year ARI.

The design peak discharges estimated by the URBS model for the Logan River at Round Mountain are within the confidence limits for the flood frequency discharge estimates for all ARIs up to 100 Year ARI floods and matches well reasonably well. However, in general, the URBS model discharges at Round Mountain are higher than the flood frequency discharges. This is a result of attempting to reconcile the URBS model discharges with the FFA estimates at Yarrahappini using a uniform catchment loss approach. The catchment area at Yarrahappini is almost double that at Round Mountain, and as such more emphasis was placed on reconciling the URBS model discharges with the FFA at Yarrahappini. As a result of this strategy the URBS model appears to overestimate discharges at Round Mountain but gives acceptable (in some cases high) discharge estimates at Yarrahappini when compared with the FFA at these two locations.

The design peak discharges estimated by the URBS model for the Logan River at Yarrahappini correspond reasonably well to the flood frequency discharge estimates for the 2, 5 and 100 Year ARI. For ARIs 10, 20 and 50 Years, the URBS model discharge estimates are higher than those predicted by the FFA; however, the URBS model discharge estimates are well within the flood frequency confidence limits. It is further noted that the URBS model predicted discharges matches very well with discharges from AWE (1997) at Yarrahappini.

The design peak discharges estimated by the URBS model for the Albert River at Bromfleet correspond very well to the flood frequency discharge estimates for all ARIs up to the 100 Year flood. This is of some significance, as Bromfleet has the longest annual peak series (76 years of data), meaning that discharge estimates for up to and including the 50 Year ARI event are reasonably certain.

The design peak discharges estimated by the URBS model in the Albert River at Wolffdene correspond adequately to the FFA discharge estimates for the 20, 50 and 100 Year ARI floods. The 2, 5, 10 and 20 Year ARI URBS model discharges are higher than the FFA estimates, but are still inside the FFA confidence limits except 2 year ARI.


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Table 44 - Comparison of URBS model and FFA estimated peak design discharges at The Overflow, Teviot Brook

ARI (years) Estimated Peak Design Discharge (m3/s)

FFA URBS

2 86 209

5 336 440

10 566 666

20 815 909

50 1159 1183

100 1421 1404

Table 45 - Comparison of URBS model and FFA estimated peak design discharges, Logan River at Round Mountain and Yarrahappini

ARI (years)



FFA URBS FFA URBS

2 453 537 572 542

5 1083 1151 1092 1284

10 1560 1691 1580 2122

20 2023 2318 2212 2960

50 2606 2971 3369 3994

100 3018 3515 4579 4838

Table 46 - Comparison of URBS model and FFA estimated peak design discharges, Albert River at Bromfleet and Wolffdene

ARI (years)


Bromfleet Wolffdene

FFA URBS FFA URBS

2 286 341 164 379

5 672 764 652 887

10 985 1094 1067 1313

20 1325 1465 1511 1738

50 1819 1877 2131 2254

100 2227 2213 2615 2667


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10. Joint Probability Approach (Monte Carlo Simulation)

The Joint Probability Approach (JPA), also referred to as the Monte Carlo simulation technique, has been under development for the last few years. Currently there are two Monte Carlo techniques available: the Total Probability Theorem (TPT) (Ref. 26) and Cooperative Research Centre – Catchment Hydrology (CRC-CH) (Ref. 28). The TPT methodology is based on current critical storm duration approach where the BOM burst IFD tables are used. The CRC-CH methodology is based on design storms of variable storm durations and the event based IFD tables are generally derived from the raw pluviographs.

Don Carroll (2013) has developed a relationship between the complete storm IFD table and the burst IFD table for the Gold Coast region as part of Council’s Hydrological Study Review in April 2013 (Ref. 3). The following relationships are established based on raw pluvio data from the BOM.

Ie = p Dq Tr Ib

Where p, q and r are constants, D is the Duration (hours), T is the ARI in years, I is the intensity. b=burst, e = event.

For Gold Coast region Don Carroll has recommended the following values (Ref. 3): p = 0.1 x 12D24 – 0.25 q = 0.6 x (1 – p) r = - 0.025 The mean duration is 0.9 x 12D241.56 where I2D24 is the 2 year 24 hour burst intensity. It is noted that both approaches have some limitations (Ref. 3). The TPT has been developed for large to extreme floods and its applications for more frequent events are questionable. The CRC-CH often applied in the derivation of design flow estimates up to large floods so this approach is not robust in the estimation of rare and extreme floods. In this study the TPT and CRC-CH Monte Carlo simulations are undertaken only to verify the results of Design Event Approach. Other limitations (Ref. 3) are: (i) the assumption that the loss distribution applied is consistent across the entire frequency range – generally higher losses are experienced with the more frequent ARI events; (ii) convective storms are typically front loaded whereas frontal storms are end loaded which is not accounted for; (iii) storm patterns are likely to be less variable with increasing ARI; and (iv) how El Nino/La Nina cycles impact antecedent conditions. It is obvious that further research work is required to apply these technologies over the entire frequency spectrum, but as applied it is likely there will be over-estimation of peak flows for the more frequent design events. The Monte Carlo simulation has been undertaken in this study for comparative purpose only with the URBS Design Event Approach (DEA). Figure 17 to Figure 23 show comparisons of design discharges at different locations using DEA and JPA modelling approaches. It was found that the TPT approach had generated average results for the Logan River Catchment and additional background work would require for this catchment to use CRC-CH technique in confidence. Overall the Monte Carlo TPT approach supported the DEA results. URBS estimated discharges from DEA and Monte Carlo simulation are shown in Appendix F (Table 47 to Table 49).


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Figure 17: Comparison of design discharge estimates from DEA and JPA modelling approach, Logan River at the Round Mountain

Figure 18: Comparison of design discharge estimates from DEA and JPA modelling approach, Logan River at the Yarrahappini


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Figure 19: Comparison of design discharge estimates from DEA and JPA modelling approach, Logan Rover at Macleans Bridge

Figure 20: Comparison of design discharge estimates from DEA and JPA modelling approach, Logan River at Waterford


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Figure 21: Comparison of design discharge estimates from DEA and JPA modelling approach, Albert River at Broomfleet

Figure 22: Comparison of design discharge estimates from DEA and JPA modelling approach, Albert River at Wolffdene


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Figure 23: Comparison of design discharge estimates from DEA and JPA modelling approach, Teivot Brook at the Overflow


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11. Conclusion

11.1 Overview

A URBS model of the Logan River catchment has been satisfactorily calibrated and verified against available data, and then the calibrated model has been used to estimate design flood discharges at key locations in the catchment for design events ranging from 2 year ARI to PMF. In addition, the URBS model design discharge estimates have been reconciled with FFA estimates of design discharges at 5 key gauging stations within the catchment. Monte Carlo simulations have also been undertaken, which produced average results to support of the discharges produced in the design event approach. However application of CRC-CH technique would require additional background work for it to be used with confidence for this catchment (Ref. 3). All analyses in this study have been undertaken using an approach and methodology consistent with the hydrologic modelling currently been undertaken for other catchments in the Gold Coast. In addition, the methodology and results of this study have been fully documented to a consistent standard.

11.2 Model Calibration and Verification

The URBS model has been calibrated against five historical flood events (January 1974, April 1990, February 1991, January 2008 and January 2013) and then verified against another four historical flood events (May 1980, April 1988, March 2004 and January 2012). The selected calibration and verification events cover a wide range of discharges across all over the Logan River Catchment.


Due to the lack of available rainfall data for most events and the lack of detailed rainfall data where data were available, the URBS model cannot be expected to accurately reproduce flood behaviour for all events and at all gauging stations. As such, more calibration emphasis was placed on large events, as the accuracy of small events are impacted significantly by spatial and temporal variation in rainfall. A single set of model parameters were adopted for the model, and maintained for all calibration and verification events. The model parameters were adjusted to achieve the best calibration across all events, resulting in a compromise between model accuracy and model simplicity. It is noted that calibration of the model for gauging stations in different parts (Teviot Brook, Upper Logan, Albert River and Lower Logan) of the Logan River catchment can be improved by adopting different sets of model parameters for each part of the catchment. Further, the calibration of the models for individual events can be improved by adopting a different set of model parameters for each of the different events. The adopted model parameters are given below:


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Rainfall losses were adjusted to achieve the best possible hydrograph shapes and flood volumes. A uniform initial loss and continuing loss rate were adopted for the model and each flood event. It is noted that calibration of the models for individual events can be improved by adopting a set of variable loss rates within the catchment for each of the different events.

11.3 Calibration Results

Satisfactory calibration was achieved throughout the catchment, with the URBS models generally reproducing recorded flood discharges adequately.

The model calibration for Teviot Brook is generally good, considering that a single set of global model parameters were adopted across all nine historical events. The model calibration results for large events are excellent; however the model results for smaller events show the predicted flood peak arriving earlier than the recorded peak. This issue could be addressed, if necessary, by adopting different model parameters including initial and continuing losses for smaller events.

The model calibration at Broomfleet and Wolffdene is generally good, given that there are some inconsistencies between recorded peak discharges at Bromfleet and Wolffdene. The model predicted excellent results at Broomfleet and Wolffdene; however results show an early peak for smaller events.

The model calibration for the Upper Logan catchment is generally excellent. Although calibration for the large events (January 1974, April 1990 and February 1991) was generally quite good at both Yarrahappini and Round Mountain gauging stations, the model predicted lower peak at Round Mountain and a slightly higher peak at Yarrahappini for smaller events (January 2008 and January 2013).

The quality of available data (both rainfall and stream flow) for the Lower Logan catchment is not as good as for the upstream of the catchment. For the January 1974, May 1980 and April 1990 flood events, the complete water level hydrographs were not recorded at the Macleans Bridge and Waterford gauges (the recorded water level hydrograph at Waterford for the January 1974 flood has been synthesised based on debris marks at the gauge site). Complete recorded water level hydrographs at both stations were available for the April 1988, February 1991, January 2008, January 2012 and January 2013 events. The two gauging stations with available data (Macleans Bridge, Waterford) are BOM flood forecasting stations, not NRW stations, and as such the quality of rating curves for these two stations is uncertain. The rating curve for Macleans Bridge appears to be acceptable; however the Waterford rating is poor, especially for higher discharges. As a result the calibration is generally good at Macleans Bridge, but somewhat poor at Waterford. The Waterford gauge is tidally affected, and may also be affected by downstream water levels (including Albert River


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outflows). The timing and shape of the predicted hydrographs at Waterford is generally acceptable but the predicted peak discharges are generally higher than recorded peak flows for the larger events. Predicted peak discharges at Macleans Bridge are generally good, indicating a problem with the Waterford rating curve. Further, the recorded flood volumes at Waterford appear to be less than those recorded at Macleans Bridge.

11.4 Design Flood Discharges

The calibrated URBS model was used to estimate design flood discharges throughout the Logan River catchment based on design rainfall intensity – frequency – duration (IFD) data from a number of sources. Design flood discharge hydrographs were estimated for a range of storm durations up to the 120 hour event for the 2, 5, 10, 20, 50, 100, 200, 500, 2000 year ARI events, and for the PMPDF and PMF events. The design rainfall data and associated procedures and input data (including IFD data, temporal patterns, areal reduction factors, and rainfall spatial distribution and design rainfall losses) adopted in the study are based on a comprehensive review of the latest available data and information.

A comparison of the estimated peak design discharges from this study with the peak design discharges reported in three previous studies (WRM 2009, Sunwater 2007 and AWE 1997) was undertaken. A summary of findings with respect to the discharge estimates from the different studies is given below. Note that the AWE (1997) and WRM (2009) studies covered the whole Logan River catchment, whereas the SunWater (2007) study was restricted to the Teviot Brook catchment.

The URBS model estimated peak design discharges for Teviot Brook at The Overflow match closely with the estimates given by the Sunwater (2007) and WRM (2009) study for all ARIs up to and including the 2000 Year ARI event.

The URBS model peak discharge estimates at Bromfleet, Wolffdene and Beenleigh match the AWE (1997) estimated peak discharges reasonably, however the URSB model estimated peak discharges at these stations are higher than those estimated by the WRM (2009) study. This is likely due to differences in adopted design rainfalls and temporal patterns between the WRM (2009) and current studies. The adopted rating curve at Wolffdene also differs substantially between the current study and the AWE (1997) study. It is also noted that an additional model (forest factor) parameter and a single set of model parameters were used for the whole Logan catchment in this study.

The URBS model peak discharge estimates at Yarrahappini match the AWE (1997) estimated peak discharges well and are higher than the WRM (2009) study. The URBS model estimated discharges at Waterford are lower than those estimated by the AWE (1997) study. The calibration and verification events selected for this study indicated that significant attenuation of flows in the Logan River occurs between Yarrahappini and Waterford (WRM 2009, Ref. 2). The URBS model developed for this study was configured to reproduce this attenuation as best as possible. The AWE (1997) study was not calibrated at Waterford, and as such no such attenuation is evident in the results from that study. The AWE (1997) study did not apply ARFs to design rainfalls.

The current study calibrated the model to two additional recent flood events (January 2012 and January 2013) than the WRM (2009) study and used an additional model parameter (forest factor) than the WRM (2009) study along with some modification of methodologies.


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11.5 Flood Frequency Analysis

Flood frequency analyses (FFA) was undertaken using the methodology recommended in Australian Rainfall and Runoff (IEAust, 1987) by fitting a Log-Pearson Type III distribution to an annual series of recorded peak flood discharges at the following key gauging stations within the catchment with more than 30 years of historical record:


Logan River at Round Mountain (DNRM GS 145008a)

Logan River at Yarrahappini (DNRM GS 145014a

Albert River at Bromfleet (DNRM GS 145102b)


The URBS model estimated peak design discharges at the above stations were compared with the peak discharge estimates obtained from the FFA to assess the consistency between the two sets of discharge estimates and reconcile any differences between the estimates from the two methods. The results were also compared with FFA results from the AWE (1997), SunWater (2007) and WRM (2009) studies. It is noted that AWE (1997) has undertaken FFA only for Logan River at Yarrahappini and Albert River at Bromfleet and Wolffdene; SunWater (2007) has undertaken FFA only for Teviot Brook at The Overflow. It is also noted that the AWE (1997) FFA are based on some 10 years less data than the analyses undertaken for this study, except at Yarrahappini, where some historical anecdotal data have been used. The results of the comparisons are summarised below.

The design peak discharges estimated by the URBS model for Teviot Brook at The Overflow correspond well to the flood frequency discharge estimates for the 20 Year ARI up to the 100 Year ARI. For ARIs less than 20 Years the URBS model discharge estimates are higher than those predicted by the FFA; however the URBS model discharge estimates are well within the flood frequency confidence limits for the 5 and 10 Year ARIs. Further to this, the URBS model results match discharges predicted by the Sunwater (2007) Teviot Brook URBS model for all ARIs, except 2 year ARI.

The design peak discharges estimated by the URBS model for the Logan River at Round Mountain are within the confidence limits for the flood frequency discharge estimates for all ARIs up to 100 Year ARI floods, and matches reasonably well. However, in general, the URBS model discharges at Round Mountain are higher than the flood frequency discharges. This is a result of attempting to reconcile the URBS model discharges with the FFA estimates at Yarrahappini using a uniform catchment loss approach. The catchment area at Yarrahappini is almost double that at Round Mountain and, as such, more emphasis was placed on reconciling the URBS model discharges with the FFA at Yarrahappini. As a result of this strategy, the URBS model appears to overestimates discharges at Round Mountain but gives acceptable (in some cases slightly high) discharge estimates at Yarrahappini when compared with the FFA at these two locations.


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The design peak discharges estimated by the URBS model for the Logan River at Yarrahappini correspond reasonably well to the flood frequency discharge estimates for the 2, 5 and 100 Year ARI. For ARIs 10, 20 and 50 Years the URBS model discharge estimates are higher than those predicted by the FFA; however, the URBS model discharge estimates are well within the flood frequency confidence limits. It is further noted that the URBS model predicted discharges match very well with discharges from AWE (1997) at Yarrahappini.

The design peak discharges estimated by the URBS model for the Albert River at Bromfleet correspond very well to the flood frequency discharge estimates for the 5 year ARIs up to the 100 Year flood. This is of some significance, as Bromfleet has the longest annual peak series (76 years of data), meaning that discharge estimates for up to, and including, the 50 Year ARI event are reasonably certain.

The design peak discharges estimated by the URBS model in the Albert River at Wolffdene correspond adequately to the FFA discharge estimates for the 50 and 100 Year ARI floods. The 2, 5, 10 and 20 Year ARI URBS model discharges are higher than the FFA estimates, but are still within the FFA confidence limits, except for the 2 year ARI.

11.6 Monte Carlo Simulation

Monte Carlo simulations were undertaken using the Total Probability Theorem approach (TPT) and Cooperative Research Centre – Catchment Hydrology approach (CRC-CH). These techniques offered an alternative to the design event approach in estimating peak discharges for various ARI events. The results of the TPT techniques gave further support of the discharges obtained from the Design Event Approach. However it was found that application of CRC-CH technique would require additional background work for it to be used with confidence for the Logan River catchment.


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12. Recommendations

The hydrological modelling undertaken in this study has revealed several issues that should be addressed in any future studies to improve the quality of design discharge estimates in the Logan River catchment:

Quality of available model calibration data for the Lower Logan River segment is not as good for the Teviot Brook, Albert River and Upper Logan River segments. This is because the data available for the lower reach is limited. Further, data are available only for two locations in the upper end of this reach (at Macleans Bridge and Waterford), and in most cases the available data are incomplete. The only two gauging stations in this river reach (at Macleans Bridge and Waterford) are BOM flood forecasting stations and not DNRM stream gauging stations. As such, the two stations have not been rated accurately. The rating curves available for these stations have been developed by BOM by correlating the recorded water levels with URBS model predicted discharges. The rating developed for Macleans Bridge appears to be acceptable but the rating updated in this study for Waterford appears to have great uncertainties for various reasons, including flows possibly bypassing the station during flood events. It is recommended that at least one of these stations (preferably Macleans Bridge) be properly rated at the earliest opportunity. Once the rating curves are upgraded, the model calibration should be reviewed and updated as deemed necessary.

All key gauging stations within the Logan River catchment have been gauged up to reasonably high discharges (The Overflow – 390 m3/s; Round Mountain – 1047 m3/s; Yarrahappini – 2844 m3/s; Bromfleet – 578 m3/s; and Wolffdene – 1214 m3/s), but not high enough to cover the full range of discharges for some of the calibrations events. The quality of the rating curves at these stations is expected to be good up to the maximum gauged discharges. However, there are some uncertainties about the quality of the rating curves above the maximum gauged discharges (i.e. extrapolated range), especially at Yarrahappini and Wolffdene. The adopted rating curve for high discharge has a significant impact on the accuracy of model calibration. Therefore, it is recommended that additional stream gauging be undertaken at these stations if a large flood event occurs in the near future. If this happens, the calibration of the URBS model should also reviewed and updated as necessary.

There are significant inconsistencies in the design rainfall estimates on either side of the Gold Coast and Logan and Albert River catchment area boundary. This is due to the significant differences between the AWE (1998) rainfall intensity and F2 and F50 factor maps and the corresponding IEAust (1987) maps, especially along the western edges of the City area. Details of these inconsistencies are given in WRM (2008b) (Ref. 19). It is recommended that the design rainfall inconsistencies at the boundaries between the Gold Coast City and Logan - Albert River catchment areas be resolved at the earliest opportunity.

WRM (2009) reported that significant attenuations of flow occur in the Logan River between Yarrahappini and Waterford. This study identified similar attenuation characteristics between Maclean’s Bridge and Waterford. The additional storage incorporated in the WRM (2009) study to model these characteristics was accordingly included in this study. However, further detailed investigations of the additional storage requirements are recommended in any future studies. This will likely require detailed 2D hydraulic modelling.


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13. Reference

1. WRM (2008a). Summary Findings of the Review of Hydrological Models for the Gold Coast City Catchments, March 2008.

2. WRM (2009). Logan River Flood Study - Hydrological Modelling, September 2009. TRACKS-#26580210-v1-WRM_LOGAN_RIVER_FLOOD_STUDY_HYDROLOGICAL_REPORT_2009.PDF

3. Don Carroll (2013). Review and Update of GCCC’s Hydrological Models, report prepared by Don Carroll Project Management Pty Ltd, April 2013.

4. AWE (1997). Southern Region of Councils, Logan and Albert Rivers Flood Plain Modelling Study Final Report, Report Prepared By Australian Water Engineering for Southern Region of Councils, December 1997.

5. Sunwater (2007). Wyaralong Dam, Design Flood Hydrology Report, Report prepared by SunWater, September 2007.

6. GCCC (2007). Logan River Catchment Hydraulic Study, August 2007. TRACKS-#19746090-REPORT LOGAN RIVER CATCHMENT - HYDRAULIC STUDY AUGUST 2007

7. GCCC (2010). Logan River Hydrological Study – Addendum Report 2010. TRACKS-#30918675-LOGAN RIVER HYDROLOGICAL STUDY - ADDENDUM REPORT 2010

8. BOM (2008). Hydrologic Techniques for Checking River Flow Ratings, C. Wright and T. Melon, Bureau of Meteorology. Source: In, Proceedings of Water Down Under 2008; pages 271 – 282. Lambert, Martin (Editor); Daniell, TM (Editor); Leonard, Michael (Editor). Modbury, SA: Engineers Australia; 2008.

9. Don Carroll (2012). URBS - A Rainfall Runoff Routing Model for Flood Forecasting and Design, Version 5.00, Manual and Software 2012 by D.G Carroll, 2012.

10. WRM 2008d. Design Event Hydrology Review, Report prepared by WRM Water and Environment Pty. Ltd, August 2008.

11. IEAust (1987). Australian Rainfall and Runoff. A Guide to Flood Estimation. 1987.

12. AWE (1998). Review of Gold Coast Rainfall Data, Final Report, May 1998, Volume 1, Report prepared by Australian Water Engineering Pty Ltd for City.

13. AWE (1992). Logan River Floodplain Filling Study. November 1992.

14. (Hargraves, c2004). Final Report, Extreme Rainfall Estimation Project, CRCFORGE and (CRC) ARF Techniques, Queensland and Border Locations, Development and Application, Report prepared by Gary Hargraves, Water Assessment Group, Water Assessment and Planning, Resource Sciences Centre, undated, circa 2004.

15. BOM (2005). A Pilot Study to Explore Methods for Deriving Design Rainfalls for Australia. 2005.

16. Hargraves, G. Extreme Rainfall Estimation Project, CRCFORGE and (CRC) ARF Techniques, Queensland and Border Locations, Development and Application. 2004.

17. IEAust. Spatial Patterns of Design Rainfall. Collation and Review of Areal Reduction Factors from Applications of the CRC-Forge Method in Australia.

18. IEAust (1999). Australian Rainfall and Runoff. A Guide to Flood Estimation. Revised Edition. 1999.


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19. WRM v7 (2008b). Revision of Design Rainfall Temporal Patterns for Gold Coast Catchments, Report prepared by WRM Water and Environment Pty. Ltd., November 2008.

20. Mahbub Ilahee. Modelling losses in Flood Estimation. PhD Thesis. Queensland University of Technology. 2005

21. BOM (2003a). The Estimation of Probable Maximum Precipitation in Australia: Generalised Short-Duration Method, Prepared by the Hydrometeorological Advisory Service, Australian Government Bureau of Meteorology, June 2003. (http://www.bom.gov.au/hydro/has/pmp.shtml on 11 October 2007)

22. BOM (2003b). Guide to the Estimation of Probable Maximum Precipitation: Generalised Tropical Storm Method, Report and accompanying CD prepared by the Hydrometeorological Advisory Service, Australian Government Bureau of Meteorology, November 2003.

23. AWE (2000). Review of Gold Coast Rainfall Data, Volume 3, Temporal Patterns, Final Report, October 2000, Report prepared by Australian Water Engineering Pty Ltd for Gold Coast City Council.

24. WDA (2009). Wyaralong Dam Design Report, 2009, report prepared by Wyaralong Dam Alliance.

25. WRM (2008c). GCCC IFD Utility Modifications, Report prepared by WRM Water and Environment Pty. Ltd., July 2008.

26. Weinman, PE et al. Use of a Monte-Carlo Framework to Characterise Hydrologic Risk. ANCOLD conference on dams. Adelaide. 2002.

27. Carroll D.G. Investigation of sub-tropical rainfall characteristics for use in the joint probability approach to Design Flood Estimation. HIC, Kyoto. 2004.

28. Carroll D.G & Rahman A (2004), “Investigation of sub-tropical rainfall characteristics for use in the joint probability approach to Design Flood Estimation” HIC, Kyoto, 2004.

29. HDA (2007). Hinze Dam, Update of Flood Hydrology, Briefing note for 23 January 2007 meeting, prepared by Hinze Dam Alliance, January 2007, Draft for discussion.

30. IEAust (1998). Australian Rainfall and Runoff, Volume 1, Institution of Engineers Australia, 1998.

31. BOM (1991). Temporal Pattern Distributions within Rainfall Bursts, Hydrology report series, HRS Report No. 1, Kennedy, M.R., Turner, L.H, Canterford, R.P. and Pearce, H.J., Bureau Of Meteorology, September 1991.


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14. Appendix A – Logan River Catchment Sub Catchment Area and Land

Uses

Sub-Catchment

Area (km2) UL UM UH UR UF

1 29.95 0 0 0 0.210384 0.789616

2 13.73 0 0 0 0.598252 0.401748

3 21.89 0 0 0 0.570123 0.429877

4 17.04 0 0 0 0.84507 0.15493

5 17.65 0 0 0 0.683286 0.316714

6 4.08 0 0 0 0.607108 0.392892

7 7.23 0 0 0 0.420055 0.579945

8 21.13 0 0 0 0.496924 0.503076

9 14.22 0 0 0 0.65647 0.34353

10 22.18 0 0 0 0.62624 0.37376

11 3.52 0 0 0 0.843466 0.156534

12 25.09 0 0 0 0.688322 0.311678

13 18.42 0 0 0 0.862649 0.137351

14 5.94 0 0 0 0.794444 0.205556

15 16.05 0 0 0 0.902181 0.097819

16 17.33 0 0 0 0.721293 0.278707

17 16.48 0 0 0 0.831917 0.168083

18 10.74 0 0 0 0.628119 0.371881

19 24.53 0 0 0 0.98247 0.01753

20 10.08 0.133929 0 0 0.866071 0

21 22.44 0.022282 0 0 0.977718 0

22 30.11 0.051146 0 0 0.805712 0.143142

23 17.74 0 0 0 0.924464 0.075536

24 18.68 0 0 0 0.753212 0.246788

25 30.83 0 0 0 0.799222 0.200778

26 21.85 0 0 0 0.609611 0.390389

27 18.86 0 0 0 0.400689 0.599311

28 24.04 0 0 0 0.328619 0.671381

29 6.4 0 0 0 0.768594 0.231406

30 13.9 0 0 0 0.361367 0.638633

31 15.78 0 0 0 0.600824 0.399176

32 5.69 0 0 0 0.304218 0.695782

101 29.15 0 0 0 0.13825 0.86175

102 22.34 0 0 0 0.175918 0.824082

103 30.67 0 0 0 0.348549 0.651451

104 23.82 0 0 0.140218 0.257347 0.602435

105 20.25 0 0 0 1 0

106 11.2 0 0 0 0.358036 0.641964

107 14.11 0 0 0 1 0

108 16.6 0 0 0 0.641566 0.358434

109 16.14 0 0 0 0.812887 0.187113


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110 14.41 0 0 0 0.51492 0.48508

111 23.54 0 0 0 0 1

112 21.82 0 0 0 0 1

113 19.25 0 0 0 0 1

114 26.5 0 0 0 0.10566 0.89434

115 13.72 0 0 0 0 1

116 18.12 0 0 0 0.320088 0.679912

117 17.17 0 0 0 0.470006 0.529994

118 17.33 0 0 0 0.874207 0.125793

119 18.68 0 0 0 0.547109 0.452891

120 24.66 0 0 0 0.340633 0.659367

121 25.66 0 0 0 0.501559 0.498441

122 28.56 0 0 0 0.527661 0.472339

123 10.32 0 0 0 0.633721 0.366279

124 22.96 0 0 0 0.280052 0.719948

125 25.51 0 0 0 0.679341 0.320659

126 7.67 0 0 0 0.752282 0.247718

127 9.71 0 0 0 0.559217 0.440783

128 4.9 0.022449 0 0 0.708163 0.269388

129 32.33 0 0 0 0 1

130 22.61 0 0 0 0.22866 0.77134

131 20.52 0 0 0 0.734405 0.265595

132 18.81 0 0 0 0.707071 0.292929

133 9.6 0 0 0 0.627083 0.372917

134 24.28 0 0 0 0.84514 0.15486

135 23.93 0 0 0 0.784789 0.215211

136 16 0 0 0 0.58625 0.41375

137 20.94 0 0 0 0.618911 0.381089

138 35.27 0 0 0 0.486816 0.513184

139 17.55 0 0 0 0.647863 0.352137

140 21.29 0 0 0 0.731799 0.268201

141 21.43 0 0 0 0.823145 0.176855

142 6.6 0 0 0 0.848485 0.151515

143 24.94 0 0 0 0.04571 0.95429

144 20.58 0 0 0 0.275024 0.724976

145 17.21 0 0 0 0.435793 0.564207

146 32.93 0 0 0 0.755238 0.244762

147 7.56 0 0 0 0.633598 0.366402

148 14.86 0 0 0 0.788694 0.211306

149 13.71 0 0 0 0.455872 0.544128

150 26.84 0 0 0 0.518629 0.481371

151 30.65 0 0 0 0.638173 0.361827

152 10.25 0 0 0 0.863415 0.136585

153 12.43 0 0 0 0.887369 0.112631


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154 16.56 0 0 0 0.952295 0.047705

155 29.42 0 0 0 0.838205 0.161795

156 15.42 0 0 0 0.953307 0.046693

157 19 0 0 0 0.914211 0.085789

158 24.51 0 0.003264 0 0.77193 0.224806

159 25.8 0 0.007364 0 0.760465 0.232171

160 21.96 0 0 0 0.735883 0.264117

161 29.75 0 0 0 0.848067 0.151933

162 23.52 0 0 0 0.88818 0.11182

163 15.25 0 0 0 1 0

164 5.02 0 0 0 0.649402 0.350598

165 20.46 0 0 0 0.895894 0.104106

166 16.59 0 0 0 0.9783 0.0217

167 22.38 0 0 0 0.243968 0.756032

168 11.33 0 0 0 0.353045 0.646955

169 16.67 0 0 0 0.538092 0.461908

170 12.86 0 0 0 0.822706 0.177294

171 18.7 0 0 0 0.882353 0.117647

172 6.37 0 0 0 1 0

173 20.5 0 0 0 1 0

174 13.18 0.174507 0 0 0.775417 0.050076

175 27.13 0 0 0 1 0

176 6.86 0.300292 0 0 0.46793 0.231778

177 7.52 0.039894 0 0 0.960106 0

178 10.26 0.082846 0 0 0.917154 0

179 15.82 0 0 0 0.839444 0.160556

180 14.68 0 0 0 0.435286 0.564714

181 16.88 0 0 0 0.538507 0.461493

182 14.28 0 0 0 0.542017 0.457983

183 23.18 0 0 0 0.572045 0.427955

184 21.58 0 0 0 1 0

185 19.94 0 0 0 1 0

186 9.29 0 0 0 1 0

187 20.41 0 0 0 0.874571 0.125429

188 17.17 0 0 0 0.946418 0.053582

189 16.8 0 0 0 0.958333 0.041667

190 20.1 0 0 0 1 0

191 5.4 0 0 0 0.738889 0.261111

192 6.73 0 0 0 0.173848 0.826152

193 18.05 0 0 0 0.756233 0.243767

194 25.64 0 0 0 0.403666 0.596334

195 23.8 0 0 0 0.387815 0.612185

196 13.88 0 0 0 0.466859 0.533141

197 15.46 0 0 0 0.43273 0.56727


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198 13.98 0 0 0 0.753934 0.246066

199 9.79 0 0 0 0.522983 0.477017

200 18.09 0 0 0 0.741846 0.258154

201 6.9 0 0 0 1 0

202 15.07 0 0 0 0.704048 0.295952

203 18.04 0 0 0 1 0

301 11.98 0 0 0.027546 0.848915 0.123539

302 23 0.003913 0 0 0.973478 0.022609

303 21.12 0.013731 0 0 0.928504 0.057765

304 20.61 0 0 0 0.255216 0.744784

305 11.56 0 0 0 0.561419 0.438581

306 18.31 0 0 0 0.224468 0.775532

307 8.7 0 0 0.025287 0.974713 0

308 15.01 0 0 0.009327 0.601599 0.389074

309 21.64 0 0 0.00647 0.942237 0.051294

310 19.87 0 0 0.018118 0.891293 0.090589

311 20.34 0 0 0.006883 0.794002 0.199115

312 15.39 0 0 0.008447 0.923327 0.068226

313 12.91 0 0 0.022463 0.943455 0.034082

314 17.38 0 0 0 0.915995 0.084005

315 21.97 0.006827 0 0 0.871643 0.121529

316 17.67 0 0 0 0.897566 0.102434

317 19.32 0 0 0.000518 0.913043 0.086439

318 17.97 0 0 0.028381 0.82749 0.144129

319 20.58 0.225948 0.025267 0.00243 0.670554 0.075802

320 15.89 0.033354 0.004405 0.028949 0.837634 0.095658

321 7.63 0.282452 0.076185 0.179713 0.413511 0.048139

322 11.51 0.528236 0 0 0.39444 0.077324

323 8.35 0.388024 0.016766 0.150898 0.150898 0.293413

324 6.51 0.400922 0 0 0.522273 0.076805

325 9.38 0.178038 0 0.154584 0.443497 0.223881

326 6.04 0.693709 0.008278 0.024834 0.046358 0.226821

327 8.22 0.059611 0 0.046229 0.262774 0.631387

328 8.29 0.306393 0.002413 0.007238 0.289505 0.394451

329 6.26 0.399361 0 0.051118 0.4377 0.111821

330 12.11 0.428571 0.049546 0.141206 0.269199 0.111478

331 6.12 0.238562 0.050654 0.058824 0.236928 0.415033

332 4.64 0.515086 0.030172 0.306034 0.131466 0.017241

333 4.71 0.509554 0.087049 0.299363 0.048832 0.055202

334 4.39 0.558087 0.189066 0.159453 0.093394 0

335 8.78 0.632118 0.042141 0.123007 0.134396 0.068337

336 8.34 0.509592 0.01199 0.029976 0.080336 0.368106

337 7.05 0.205674 0.01844 0.18156 0.506383 0.087943

338 8.94 0.038916 0.367177 0.191725 0.391711 0.010471


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Sub-Catchment


339 5.65 0.003051 0.095198 0.201919 0.47546 0.224372

340 6.59 0.053801 0.309949 0.39426 0.175328 0.066662

341 9.83 0.491353 0.023398 0.131231 0.258393 0.095626

342 7.64 0 0 0 0.854712 0.145288

343 6.93 0.305916 0.015873 0.005772 0.327561 0.344877

344 7.84 0.012857 0.076273 0.145377 0.693913 0.07158

345 20.88 0.000328 0.000566 0.05128 0.742031 0.205795

346 12.35 0.003297 0.075482 0.144192 0.613952 0.163077

347 8.46 0 0.078775 0.206284 0.597163 0.117778

348 10.02 0.023495 0.113381 0.395702 0.416235 0.051188

349 8.62 0.111326 0.000319 0.185416 0.654711 0.048229

350 10.89 0 0 0.279601 0.683774 0.036625

351 7.32 0.040984 0 0 0.698087 0.260929

352 8.69 0.054085 0 0 0.808976 0.136939

353 11.23 0 0 0.002671 0.503117 0.494212

354 9.17 0 0 0 0.308615 0.691385

355 7.69 0 0 0.063719 0.559168 0.377113

356 6.36 0.056046 0.02861 0.201311 0.631534 0.0825

357 9.26 0.040313 0.062173 0.278354 0.465737 0.153423

358 13.3 0 0.023256 0.043341 0.891305 0.042098

359 9.58 0.073622 0 0.301828 0.513813 0.110737

360 15.55 0 0 0.016077 0.963344 0.020579

361 14.03 0 0 0.224519 0.711333 0.064148

362 2.71 0 0 0 0.99631 0.00369

363 2.82 0 0 0 1 0

364 3.89 0 0 0 1 0

365 3.49 0 0 0 1 0

366 1.87 0 0 0 1 0

367 2.69 0 0 0 1 0

368 3.65 0.071233 0 0.545205 0.268493 0.115068

401 14.96 0 0 0 0.040775 0.959225

402 15.77 0 0 0 0.453393 0.546607

403 16.27 0 0 0 0.089121 0.910879

404 9.56 0 0 0.349372 0.0659 0.584728

405 10.66 0 0 0 0.386492 0.613508

406 14.72 0 0 0 0.302989 0.697011

407 17.34 0 0 0 0.38812 0.61188

408 13.92 0 0 0 0.366379 0.633621

409 14.96 0 0 0 0.572861 0.427139

410 14.1 0 0 0 0.614894 0.385106

411 13.61 0 0 0 0.758266 0.241734

412 8.55 0 0 0 0.892398 0.107602

413 10.02 0 0 0 1 0

414 18.54 0 0 0 0.652643 0.347357


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415 28.92 0 0 0 0.257607 0.742393

416 13.37 0 0 0 0.463725 0.536275

417 13.53 0 0 0 0.747228 0.252772

418 14.68 0 0 0 0.860354 0.139646

419 14.29 0 0 0 0.782365 0.217635

420 25.28 0 0 0 0.795095 0.204905

421 11.76 0 0 0 0.930272 0.069728

422 24.4 0 0 0 0.742623 0.257377

423 4.5 0 0 0 0.766667 0.233333

424 17.95 0 0 0 0 1

425 10.8 0 0 0 0 1

426 13.52 0 0 0 0 1

427 9.82 0 0 0 0.323829 0.676171

428 12.22 0 0 0 0.462357 0.537643

429 10.97 0 0 0 0.345488 0.654512

430 12.72 0 0 0 0.431604 0.568396

431 12.62 0.086371 0 0 0.298732 0.614897

432 16.29 0 0 0 0.330878 0.669122

433 18.67 0 0 0 0.595608 0.404392

434 17.25 0 0 0 0.516522 0.483478

435 13.34 0 0 0 0.581709 0.418291

436 15.58 0 0 0 0.72914 0.27086

437 18.11 0 0 0 0.599117 0.400883

438 15.36 0 0 0 0.83138 0.16862

439 23.51 0 0 0 0.568269 0.431731

440 12.61 0 0 0 0.926249 0.073751

441 18.39 0 0 0 0.672104 0.327896

442 14.6 0 0 0 0.669178 0.330822

443 18.18 0.013751 0 0 0.453245 0.533003

444 9.93 0 0 0 0.704935 0.295065

445 16.59 0.036166 0 0 0.271851 0.691983

446 14.9 0 0 0 0.234899 0.765101

447 24.81 0 0 0 0.403063 0.596937

448 8.14 0 0 0 0.391892 0.608108


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15. Appendix B – URBS Catchment Definition File

Logan URBS model (URBS model created by November 2014) {combined Teviot Brook, Albert River, Upper Logan and Lower Logan River from WRM study 2009 and Addendum 2010}{Wyaralong Dam and Cedar Grove Dam modelled} MODEL: SPLIT USES: L,F*0.5,U DEFAULT PARAMETERS: alpha=0.20 m=0.75 beta=2.5 n=1.0 CATCHMENT DATA FILE = All_Logan.csv {Teviot Brook Catchment Definition} FACTOR = 0.75 {*****************} RAIN #1 L=5.54 ROUTE THRU #2 L=0.91 STORE. RAIN #2 L=1.64 GET. ROUTE THRU #2 L=2.83 STORE. RAIN #3 L=7.75 GET. ROUTE THRU #4 L=3.77 ADD RAIN #4 L=2.51 PRINT. CROFTBY {NRW GS 145011A, X=457799.01 Y=6886232.17} FACTOR = 1.0 {*****************} ROUTE THRU #5 L=2.20 ADD RAIN #5 L=4.89 ROUTE THRU #6 L=2.03 ADD RAIN #6 L=2.09 ROUTE THRU #7 L=3.10 STORE. RAIN #7 L=2.55 GET. ROUTE THRU #7 L=0.52 STORE. RAIN #8 L=6.07 GET. ROUTE THRU #14 L=0.63 STORE. RAIN #9 L=4.28 ROUTE THRU #10 L=3.60 ADD RAIN #10 L=5.21 ROUTE THRU #11 L=1.88 ADD RAIN #11 L=2.36 STORE. RAIN #12 L=6.91 GET. ROUTE THRU #13 L=0.39 STORE. RAIN #13 L=5.71 GET. ROUTE THRU #13 L=0.55 ROUTE THRU #14 L=2.25 ADD RAIN #14 L=1.16 GET. ROUTE THRU #14 L=2.76 STORE. RAIN #15 L=3.87 GET. ROUTE THRU #16 L=1.15 ADD RAIN #16 L=2.75 STORE. RAIN #17 L=5.07 GET. ROUTE THRU #18 L=0.81 STORE. RAIN #18 L=2.98 GET. ROUTE THRU #19 L=0.89 STORE. RAIN #19 L=5.52 GET. ROUTE THRU #19 L=0.65 ROUTE THRU #20 L=1.70 ADD RAIN #20 L=2.41 PRINT. BOONAH {BOM GS 040949, X=469212.76 Y=6902331.59} ROUTE THRU #21 L=1.18 STORE. RAIN #21 L=3.04 GET. ROUTE THRU #21 L=1.31 STORE. RAIN #22 L=5.28 GET. ROUTE THRU #21 L=1.02


Page 115 of 175

ROUTE THRU #23 L=2.11 ADD RAIN #23 L=2.14 ROUTE THRU #24 L=0.94 ADD RAIN #24 L=0.69 ROUTE THRU #25 L=5.13 ADD RAIN #25 L=3.54 ROUTE THRU #26 L=0.70 STORE. RAIN #26 L=2.03 GET. ROUTE THRU #26 L=2.46 ROUTE THRU #27 L=2.52 ADD RAIN #27 L=3.47 ROUTE THRU #28 L=0.98 STORE. RAIN #28 L=3.96 GET. ROUTE THRU #28 L=2.90 PRINT. THE_OVERFLOW {NRW GS 145012A, X=486159.23 Y=6910581.41} ROUTE THRU #29 L=1.40 ADD RAIN #29 L=3.99 STORE. RAIN #30 L=3.72 ROUTE THRU #31 L=3.38 ADD RAIN #31 L=4.11 GET. ROUTE THRU #32 L=1.12 ADD RAIN #32 L=0.72 {PRINT. TEVIOT_OUT} {WYARALONG DAM SITE, X=488488.76 Y=6912931.62} {WYARALONG dam - ONLY INCLUDED FOR JAN 2012, JAN 2013 EVENT AND DESIGN RUNS} {DAM ROUTE VBF=0 NUMBER=34} DAM ROUTE FSL=63.6 DATAFILE=WYARALONG IL=63.6 NUMBER=34 0 0 4931 58 11338 201 18029 401 25019 647 32325 937 39945 1349 47865 1863 56072 2466 64563 3157 73365 3937 82569 4807 92162 5761 102151 6792 112513 7886 123234 9031 134318 10200 145776 11500 157665 12600 170025 13800 182837 15000 196106 16300 209838 17600 224017 18900 238594 20200 253564 21500 268934 22800 284719 24200 300909 25600 317504 26800 334504 28200 351939 29600 369817 30950 388121 32500 {END OF Teviot Brook CATCHMENT DATA} {Starts Upper Logan River Catchment Definition} FACTOR = 1.0 {**********************************************************} ROUTE THRU #191 L=1.86 ADD RAIN #191 L=1.82 STORE. RAIN #192 L=3.21 GET. ROUTE THRU #193 L=3.39 ADD RAIN #193 L=3.54 STORE. RAIN #194 L=3.05 ROUTE THRU #195 L=3.68 STORE. RAIN #195 L=3.25 GET. ROUTE THRU #195 L=2.19 ROUTE THRU #196 L=2.92 STORE.


Page 116 of 175

RAIN #196 L=3.56 GET. ROUTE THRU #196 L=1.30 STORE. RAIN #197 L=3.35 ROUTE THRU #198 L=2.67 ADD RAIN #198 L=4.20 GET. ROUTE THRU #199 L=2.08 ADD RAIN #199 L=2.54 GET. {GET from store at the end of Rain#193} ROUTE THRU #200 L=0.82 STORE. RAIN #200 L=2.54 GET. FACTOR = 2.0 {************************************************} ROUTE THRU #200 L=2.45 STORE. FACTOR = 0.5 {*******************************************************************} RAIN #101 L=3.97 ROUTE THRU #102 L=1.38 ADD RAIN #102 L=1.60 ROUTE THRU #103 L=2.97 ADD RAIN #103 L=3.35 ROUTE THRU #104 L=3.25 ADD RAIN #104 L=4.10 {MAROON DAM - ADOPTED SUNWATER STAGE-VOL, BOM SPILLWAY DISCHARGE RATING & ADOPTED SPILLWAY LEVEL OF 207.14 FROM NRW} DAM ROUTE VBF=0 NUMBER=22 0.0 0 201.4 13.3 880.6 57.6 1564.7 110.0 2253.3 163.3 2946.7 216.7 3644.9 287.1 4347.9 359.4 5055.7 431.8 5768.3 533.3 6485.5 638.1 7207.1 734.1 7933.2 816.7 8664.1 1049.1 9399.2 1303.8 10138.9 1574.3 10883.1 1867.7 11632.1 2340.7 12385.9 2727.2 13144.7 3112.3 13908.6 3512.9 14677.6 4133.5 PRINT. MAROON_HW {NRW GS 145021A, X=466288.24 Y=6882661.38} ROUTE THRU #105 L=1.32 ADD RAIN #105 L=3.14 STORE. RAIN #106 L=6.07 GET. ROUTE THRU #107 L=2.20 ADD RAIN #107 L=2.24 ROUTE THRU #108 L=1.20 STORE. RAIN #108 L=2.20 GET. ROUTE THRU #108 L=1.18 ROUTE THRU #109 L=2.82 ADD RAIN #109 L=2.46 ROUTE THRU #110 L=3.67 ADD RAIN #110 L=3.37 STORE. FACTOR = 0.25 {***********************************************} RAIN #111 L=2.34 ROUTE THRU #112 L=2.13 ADD RAIN #112 L=3.58 ROUTE THRU #113 L=2.92 STORE. RAIN #113 L=2.36 GET. ROUTE THRU #113 L=2.15 ROUTE THRU #114 L=0.82 ADD RAIN #114 L=2.80 STORE. RAIN #115 L=3.32 STORE. RAIN #116 L=4.57 GET. ROUTE THRU #117 L=3.62 ADD RAIN #117 L=3.44 ROUTE THRU #118 L=2.44


Page 117 of 175

STORE. RAIN #118 L=3.86 GET. ROUTE THRU #118 L=0.60 GET. ROUTE THRU #119 L=2.71 ADD RAIN #119 L=3.78 PRINT. FOREST_HOME {NRW GS 145003B, X=478115.41 Y=6881088.23} FACTOR = 0.5 {***********************************************} GET. ROUTE THRU #120 L=3.23 ADD RAIN #120 L=1.71 ROUTE THRU #121 L=1.35 ADD RAIN #121 L=5.92 STORE. FACTOR = 0.25 {***********************************************} RAIN #122 L=4.38 ROUTE THRU #123 L=2.92 STORE. RAIN #123 L=2.27 GET. ROUTE THRU #123 L=3.07 STORE. RAIN #124 L=5.39 GET. ROUTE THRU #125 L=3.61 ADD RAIN #125 L=5.13 STORE. RAIN #126 L=3.16 GET. ROUTE THRU #127 L=1.87 ADD RAIN #127 L=3.55 FACTOR = 1.0 {***********************************************} GET. ROUTE THRU #128 L=0.96 ADD RAIN #128 L=2.33 PRINT. RATHDOWNEY {NRW GS 145020A, X=487151.47 Y=6878981.63} ROUTE THRU #136 L=1.11 STORE. FACTOR = 0.25 {***********************************************} RAIN #129 L=4.93 ROUTE THRU #130 L=3.55 ADD RAIN #130 L=4.57 ROUTE THRU #131 L=3.73 ADD RAIN #131 L=5.18 ROUTE THRU #132 L=3.25 ADD RAIN #132 L=4.43 STORE. RAIN #133 L=3.89 GET. ROUTE THRU #134 L=0.82 STORE. RAIN #134 L=2.02 GET. ROUTE THRU #134 L=4.60 PRINT. DIECKMANS_BR {NRW GS 145010A, X=488844.0, Y=6875772.2} STORE. RAIN #135 L=6.54 GET. ROUTE THRU #136 L=1.94 ADD RAIN #136 L=3.33 FACTOR = 1.4 {***********************************************} GET. ROUTE THRU #137 L=2.21 ADD RAIN #137 L=5.03 ROUTE THRU #138 L=0.87 STORE. RAIN #138 L=6.46 GET. ROUTE THRU #138 L=4.11 STORE. RAIN #139 L=4.90 STORE. RAIN #140 L=3.35 GET. ROUTE THRU #140 L=1.61 ROUTE THRU #141 L=2.26 ADD RAIN #141 L=3.21 GET. ROUTE THRU #142 L=2.69 ADD RAIN #142 L=2.12 STORE. FACTOR = 0.5 {*************************************************************************} RAIN #143 L=5.32 ROUTE THRU #144 L=3.48 ADD RAIN #144 L=2.86 ROUTE THRU #145 L=1.66


Page 118 of 175

ADD RAIN #145 L=6.42 STORE. RAIN #146 L=4.91 GET. ROUTE THRU #147 L=1.77 ADD RAIN #147 L=2.21 STORE. RAIN #148 L=3.61 ROUTE THRU #149 L=4.16 ADD RAIN #149 L=5.85 GET. ROUTE THRU #150 L=3.20 ADD RAIN #150 L=3.78 PRINT. RUDDS_LANE {NRW GS 145013A, X=498379.57, Y=6884061.31} ROUTE THRU #151 L=2.55 ADD RAIN #151 L=2.95 ROUTE THRU #152 L=2.70 STORE. RAIN #152 L=1.99 FACTOR = 1.4 {*******************************************************************} GET. ROUTE THRU #152 L=2.78 GET. ROUTE THRU #153 L=1.31 STORE. RAIN #153 L=4.55 GET. ROUTE THRU #154 L=3.02 STORE. RAIN #154 L=2.60 GET. ROUTE THRU #154 L=2.29 STORE. FACTOR = 1.0 {************************************************} RAIN #155 L=2.75 ROUTE THRU #156 L=2.59 ADD RAIN #156 L=3.06 ROUTE THRU #157 L=2.01 ADD RAIN #157 L=2.65 ROUTE THRU #158 L=3.58 ADD RAIN #158 L=3.84 ROUTE THRU #159 L=2.86 ADD RAIN #159 L=6.08 STORE. RAIN #160 L=5.70 ROUTE THRU #161 L=3.49 ADD RAIN #161 L=5.17 ROUTE THRU #162 L=4.71 STORE. RAIN #162 L=1.71 GET. ROUTE THRU #162 L=3.32 GET. ROUTE THRU #163 L=3.74 ADD RAIN #163 L=3.59 GET. FACTOR = 2.0 {*****************************************************} STORE. RAIN #164 L=2.91 GET. PRINT. ROUND_MOUNTAIN {NRW GS 145008A, X=492663.21 Y=6894659.83} ROUTE THRU #165 L=1.28 STORE. RAIN #165 L=2.83 GET. ROUTE THRU #165 L=2.89 ROUTE THRU #166 L=2.99 ADD RAIN #166 L=3.79 STORE. RAIN #167 L=8.02 STORE. RAIN #168 L=6.19 GET. ROUTE THRU #169 L=0.74 STORE. RAIN #169 L=5.34 GET. ROUTE THRU #169 L=1.21 ROUTE THRU #170 L=1.61 STORE. RAIN #170 L=1.42 GET. ROUTE THRU #170 L=6.17 GET. {BROMELTON WEIR OMITTED FROM MODEL DUE TO SMALL SIZE AND LACK OF DATA Depth Above Storage Spillway Discharge Spillway (m) (ML) (m3/s)


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0 0 0 0.25 48.2 7.5 0.50 99.4 23.5 1.00 210.3 53.0 1.25 270.7 76.0 1.30 283.2 91.0 2.00 ???? 190.0 SPILLWAY LEVEL 40.7m - NO STORAGE DATA ABOVE 42.0m} ROUTE THRU #171 L=3.08 STORE. RAIN #171 L=4.61 GET. ROUTE THRU #171 L=1.01 ROUTE THRU #172 L=1.93 ADD RAIN #172 L=1.69 STORE. RAIN #173 L=3.72 ROUTE THRU #174 L=2.17 ADD RAIN #174 L=3.09 STORE. RAIN #175 L=5.82 GET. ROUTE THRU #176 L=1.20 STORE. RAIN #176 L=1.87 GET. ROUTE THRU #176 L=1.12 GET. ROUTE THRU #176 L=0.65 STORE. RAIN #177 L=2.72 GET. PRINT. BEAUDESERT {NRW GS 145001A / BOM GS 040939, X=498593.61 Y=6906468.57} ROUTE THRU #178 L=2.47 ADD RAIN #178 L=3.52 STORE. FACTOR = 1.0 {***********************************************************} RAIN #179 L=4.57 ROUTE THRU #180 L=4.87 ADD RAIN #180 L=3.26 STORE. RAIN #181 L=5.30 ROUTE THRU #182 L=4.01 ADD RAIN #182 L=3.91 GET. ROUTE THRU #183 L=3.95 ADD RAIN #183 L=5.34 ROUTE THRU #184 L=3.41 ADD RAIN #184 L=4.60 ROUTE THRU #185 L=3.49 STORE. RAIN #185 L=3.06 GET. ROUTE THRU #185 L=0.62 GET. FACTOR = 2.0 {***********************************************************} ROUTE THRU #186 L=2.43 ADD RAIN #186 L=0.51 STORE. RAIN #187 L=3.24 ROUTE THRU #188 L=1.73 STORE. RAIN #188 L=1.57 GET. ROUTE THRU #188 L=2.97 GET. ROUTE THRU #186 L=1.83 STORE. RAIN #189 L=4.72 GET. ROUTE THRU #189 L=0.52 ROUTE THRU #190 L=3.88 STORE. RAIN #190 L=2.44 GET. ROUTE THRU #190 L=2.53 GET. {get from at the end of store route thru #200} FACTOR = 2.0 {************************************************} ROUTE THRU #201 L=1.43 ADD RAIN #201 L=2.11 {CEDAR GROVE WEIR - ONLY INCLUDED FOR JAN 2008 EVENT AND DESIGN RUNS} DAM ROUTE VBF=0 NUMBER=14 0 0.0 245 28.0 518 80.9 821 142.7 1156 222.3


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1523 311.9 1925 401.5 2363 491.0 2838 567.0 3348 641.5 3896 716.0 4485 790.4 5114 877.1 5783 1012.9 {INPUT.DS_CEDARWEIR} {PRINT. DS_CEDARWEIR} ROUTE THRU #203 L=1.74 STORE. RAIN #202 L=4.04 ROUTE THRU #203 L=1.85 ADD RAIN #203 L=3.64 GET. ROUTE THRU #203 L=1.48 PRINT. YARRAHAPPINI {NRW GS 145014A, X=498665.14 Y=6921377.41} PRINT. UPPER_OUT {End of Upper Logan catchment data*******************************} {Start Lower Logan Catchment Definition up to Sub catchment 344} {Dummy dam routing to increase main channel routing} DAM ROUTE. VBF=0 a=0.15 b=1.6 ROUTE THRU #301 L=1.36 ADD RAIN #301 L=3.56 STORE. RAIN #302 L=5.78 STORE. RAIN #303 L=4.03 GET. ROUTE THRU #302 L=0.77 GET. ROUTE THRU #307 L=2.12 STORE. RAIN #304 L=5.84 STORE. RAIN #305 L=3.60 GET. ROUTE THRU #304 L=1.01 STORE. RAIN #306 L=6.55 GET. ROUTE THRU #307 L=2.12 ADD RAIN #307 L=0.95 GET. ROUTE THRU #307 L=0.89 ROUTE THRU #308 L=1.74 STORE. RAIN #308 L=4.87 GET. ROUTE THRU #308 L=0.53 ROUTE THRU #309 L=0.52 STORE. RAIN #309 L=3.17 GET. ROUTE THRU #309 L=2.02 PRINT. MACLEANS_BR {BOM GS 040935, X=501685.57 Y=6926441.47} {Dummy dam routing to increase main channel routing} DAM ROUTE. VBF=0 a=0.13 b=1.30 ROUTE THRU #310 L=2.33 ADD RAIN #310 L=5.36 ROUTE THRU #311 L=1.11 STORE. RAIN #311 L=4.48 GET. ROUTE THRU #311 L=1.97 ROUTE THRU #312 L=2.02 STORE. RAIN #312 L=2.32 GET. ROUTE THRU #312 L=0.79 ROUTE THRU #313 L=1.74 STORE. RAIN #313 L=1.75 GET. ROUTE THRU #313 L=3.61 STORE. RAIN #314 L=2.22 ROUTE THRU #315 L=2.12 ADD RAIN #315 L=4.97 GET. STORE. RAIN #316 L=3.21 ROUTE THRU #317 L=5.60 ADD RAIN #317 L=4.13 GET.


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ROUTE THRU #318 L=0.67 STORE. RAIN #318 L=2.54 GET. ROUTE THRU #318 L=6.92 STORE. RAIN #319 L=3.38 GET. ROUTE THRU #320 L=2.10 STORE. RAIN #320 L=2.38 GET. ROUTE THRU #320 L=2.48 PRINT. WATERFORD {BOM GS 040878, X=513721.15 Y=6936821.54} ROUTE THRU #321 L=1.03 ADD RAIN #321 L=3.95 ROUTE THRU #337 L=0.50 STORE. FACTOR = 2.5 {*************************************************} RAIN #322 L=3.66 STORE. RAIN #323 L=2.08 GET. ROUTE THRU #324 L=0.76 STORE. RAIN #324 L=2.06 GET. ROUTE THRU #324 L=0.85 ROUTE THRU #325 L=2.56 STORE. RAIN #325 L=2.47 GET. ROUTE THRU #325 L=0.26 STORE. RAIN #326 L=1.28 ROUTE THRU #327 L=1.26 ADD RAIN #327 L=3.63 GET. ROUTE THRU #329 L=1.98 STORE. RAIN #328 L=2.75 GET. ROUTE THRU #329 L=1.15 STORE. RAIN #329 L=1.22 GET. ROUTE THRU #329 L=0.37 PRINT. FIRST_AV {BOM GS 540078, X=510221.55 Y=6939699.47} ROUTE THRU #330 L=3.68 ADD RAIN #330 L=4.41 STORE. RAIN #331 L=1.82 ROUTE THRU #332 L=0.71 ADD RAIN #332 L=0.44 ROUTE THRU #333 L=0.24 STORE. RAIN #333 L=1.02 GET. ROUTE THRU #333 L=1.19 ROUTE THRU #334 L=0.46 STORE. RAIN #334 L=0.94 GET. ROUTE THRU #334 L=0.65 PRINT. RESERVE_ {BOM GS 540079, X=512715.48, Y=6943405.69} ROUTE THRU #335 L=1.11 ADD RAIN #335 L=1.46 GET. PRINT. LOGANLEA {BOM GS 540091, X=514468.57 Y=6941871.87} FACTOR = 1.0 {*************************************************} ROUTE THRU #337 L=0.99 STORE. RAIN #336 L=2.21 GET. ROUTE THRU #337 L=1.80 ADD RAIN #337 L=1.29 GET. ROUTE THRU #337 L=0.44 ROUTE THRU #338 L=1.94 ADD RAIN #338 L=0.00 PRINT. Sc338_TH {GCCC HYDRAULIC MODEL LOGAN RIVER UPSTREAM BOUNDARY Sc38, X=516754.76 Y=6937207.24} ROUTE THRU #338 L=2.56 STORE. RAIN #339 L=0.00 PRINT. Sc339_LH {X=517563.76 Y=6934153.95} ROUTE THRU #339 L=2.27 GET.


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ROUTE THRU #340 L=1.14 STORE. RAIN #340 L=0.00 PRINT. Sc340_LH {X=519083.87 Y=6935791.51} GET. ROUTE THRU #340 L=2.00 PRINT. EAGLEBY {BOM GS 040709, X=519603.9 Y=6936683.8} ROUTE THRU #344 L=1.32 STORE. RAIN #341 L=0.00 PRINT. Sc341_LH {X=518365.11 Y=6939335.95} ROUTE THRU #341 L=2.49 GET. ROUTE THRU #344 L=1.67 STORE. RAIN #342 L=0.00 PRINT. Sc342_LH {X=521543.46 Y=6941323.96} ROUTE THRU #342 L=1.97 ROUTE THRU #343 L=0.33 STORE. RAIN #343 L=0.00 PRINT. Sc343_LH {X=520551.80 Y=6940462.78} ROUTE THRU #343 L=0.84 GET. ROUTE THRU #343 L=2.58 GET. STORE. RAIN #344 L=0.00 PRINT. Sc344_LH {X=521706.57 Y=6938251.10} GET. ROUTE THRU #344 L=3.51 STORE. {at the confluence of Logan River} {Start Albert River Catchment Definition****************} FACTOR=1.0 {****************************************************} RAIN #401 L=4.57 ROUTE THRU #402 L=4.07 ADD RAIN #402 L=6.00 STORE. RAIN #403 L=5.41 STORE. RAIN #404 L=3.22 GET. ROUTE THRU #405 L=2.49 ADD RAIN #405 L=3.82 GET. ROUTE THRU #405 L=1.23 ROUTE THRU #407 L=1.55 STORE. RAIN #406 L=4.66 GET. ROUTE THRU #407 L=2.54 ADD RAIN #407 L=5.36 STORE. RAIN #408 L=4.46 GET. ROUTE THRU #409 L=1.77 ADD RAIN #409 L=3.29 ROUTE THRU #410 L=1.96 ADD RAIN #410 L=2.35 STORE. RAIN #411 L=4.08 GET. ROUTE THRU #412 L=3.07 ADD RAIN #412 L=1.98 PRINT. LUMEAH {NRW GS 145101D, X=504077.12 Y=6896040.93} ROUTE THRU #413 L=2.50 STORE. RAIN #414 L=8.11 GET. ADD RAIN #413 L=2.07 STORE. RAIN #415 L=8.00 STORE. RAIN #416 L=2.48 GET. ROUTE THRU #416 L=1.31 ROUTE THRU #417 L=3.61 ADD RAIN #417 L=2.01 ROUTE THRU #418 L=1.74 ADD RAIN #418 L=2.45 GET. ROUTE THRU #413 L=0.71 ROUTE THRU #419 L=1.04 ADD RAIN #419 L=2.22 PRINT. BEAUD_PS {NRW GS 145105A/145105B, X=506380.92 Y=6902846.21} FACTOR = 1.0 {***************************************************}


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ROUTE THRU #420 L=2.94 ADD RAIN #420 L=4.34 ROUTE THRU #421 L=2.51 ADD RAIN #421 L=5.04 STORE. RAIN #422 L=5.23 GET. ROUTE THRU #423 L=1.58 ADD RAIN #423 L=2.00 STORE. FACTOR = 0.75 {**********************************************************} RAIN #424 L=5.05 STORE. RAIN #425 L=4.92 GET. ROUTE THRU #426 L=2.18 ADD RAIN #426 L=2.40 ROUTE THRU #427 L=1.47 ADD RAIN #427 L=2.90 ROUTE THRU #428 L=2.18 ADD RAIN #428 L=3.82 ROUTE THRU #429 L=2.81 ADD RAIN #429 L=2.56 ROUTE THRU #430 L=2.75 ADD RAIN #430 L=3.71 ROUTE THRU #431 L=2.74 ADD RAIN #431 L=3.86 PRINT. BENOBBLE {NRW GS 145107A, X=515585.59 Y=6903070.24} FACTOR = 1.0 {***************************************************} ROUTE THRU #432 L=2.75 ADD RAIN #432 L=2.35 ROUTE THRU #433 L=2.20 ADD RAIN #433 L=3.34 STORE. RAIN #434 L=2.74 ROUTE THRU #435 L=0.93 STORE. RAIN #435 L=1.32 GET. ROUTE THRU #435 L=1.51 ROUTE THRU #436 L=1.87 ADD RAIN #436 L=2.92 GET. ROUTE THRU #437 L=2.73 ADD RAIN #437 L=3.84 GET. PRINT. BROMFLEET {NRW GS 145102B, X=510488.13 Y=6912616.12} FACTOR = 1.0 {***************************************************} ROUTE THRU #438 L=2.73 ADD RAIN #438 L=1.23 STORE. RAIN #439 L=4.32 GET. ROUTE THRU #438 L=2.31 ROUTE THRU #440 L=3.74 ADD RAIN #440 L=2.16 STORE. RAIN #441 L=4.48 GET. ROUTE THRU #440 L=0.93 ROUTE THRU #442 L=0.34 STORE. RAIN #442 L=4.33 GET. ROUTE THRU #442 L=1.28 ROUTE THRU #443 L=0.45 STORE. RAIN #443 L=3.34 GET. ROUTE THRU #443 L=1.75 ROUTE THRU #444 L=0.94 STORE. RAIN #444 L=1.07 GET. ROUTE THRU #444 L=1.92 STORE. FACTOR = 1.0 {***************************************************} RAIN #445 L=6.41 ROUTE THRU #446 L=2.63 ADD RAIN #446 L=4.64 GET. FACTOR = 1.0 {***************************************************} ROUTE THRU #447 L=2.05 ADD RAIN #447 L=2.18 ROUTE THRU #448 L=1.59 STORE. RAIN #448 L=0.83


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GET. PRINT. Sc448_TH {GCCC HYDRAULIC MODEL ALBERT RIVER UPSTREAM BOUNDARY Sc48, X=517762.18 Y=6925442.64} ROUTE THRU #448 L=1.80 PRINT. WOLFFDENE {NRW GS 145196A, X=518743.3 Y=6926860.23} PRINT. ALBERT_OUT {End Albert River Catchment Definition} {Starts Lower Logan at the end of Albert Catchment} FACTOR = 1.0 {***************************************************} ROUTE THRU #345 L=2.58 STORE. RAIN #345 L=0.00 PRINT. Sc345_LH {X=519074.32 Y=6928260.31} GET. ROUTE THRU #345 L=2.01 ROUTE THRU #347 L=1.70 STORE. RAIN #346 L=0.00 PRINT. Sc346_LH {X=517661.24 Y=6931496.74} ROUTE THRU #346 L=2.95 GET. STORE. RAIN #347 L=0.00 PRINT. Sc347_LH {X=519925.21 Y=6931587.90} GET. ROUTE THRU #347 L=2.91 PRINT. BEENLEIGH {BOM GS 040723, X=521806.37 Y=6933129.29} ROUTE THRU #348 L=1.59 STORE. RAIN #348 L=0.00 PRINT. Sc348_LH {X=522045.83 Y=6933853.85} GET. ROUTE THRU #348 L=1.17 ROUTE THRU #349 L=3.02 STORE. RAIN #349 L=0.00 PRINT. Sc349_LH {X=521745.71 Y=6935745.84} ROUTE THRU #349 L=2.10 GET. ROUTE THRU #349 L=0.82 GET. {CONFLUENCE WITH LOGAN R} FACTOR = 2.5 {********************************************************} ROUTE THRU #350 L=2.24 STORE. RAIN #350 L=0.00 PRINT. Sc350_LH {X=525731.95 Y=6936763.60} GET. ROUTE THRU #350 L=1.96 STORE. RAIN #351 L=1.67 PRINT. Sc351_TH {X=525231.13 Y=6942394.63} {NOTE. PRINT STATEMENT LOCATED AT GCCC HYDRAULIC MODEL BOUNDARY} ROUTE THRU #352 L=3.00 STORE. RAIN #352 L=0.00 PRINT. Sc352_LH {X=523800.81 Y=6940736.79} GET. ROUTE THRU #352 L=2.69 ROUTE THRU #353 L=2.78 STORE. RAIN #353 L=0.00 PRINT. Sc353_LH {X=526045.11 Y=6939862.56} ROUTE THRU #353 L=2.16 GET. ROUTE THRU #353 L=2.17 GET. PRINT. RIEDEL_RD {BOM GS 540236, X=527601.74 Y=6936465.94} ROUTE THRU #355 L=0.82 STORE. RAIN #354 L=0.00 PRINT. Sc354_LH {X=527747.90 Y=6939980.00} ROUTE THRU #354 L=2.87 ROUTE THRU #355 L=0.40 STORE. RAIN #355 L=0.00 PRINT. Sc355_LH {X=528935.29 Y=6938244.58} ROUTE THRU #355 L=0.70 GET. ROUTE THRU #355 L=1.10 GET. ROUTE THRU #355 L=1.62 ROUTE THRU #361 L=1.54 STORE. RAIN #356 L=0.00 PRINT. Sc356_LH {X=524387.98 Y=6927127.47} ROUTE THRU #356 L=2.75 STORE. RAIN #357 L=0.00 PRINT. Sc357_LH {X=523044.01 Y=6928817.22}


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ROUTE THRU #357 L=3.26 GET. ROUTE THRU #358 L=0.83 STORE. RAIN #358 L=0.00 PRINT. Sc358_LH {X=526951.96 Y=6929365.25} ROUTE THRU #358 L=0.98 GET. ROUTE THRU #358 L=0.69 STORE. RAIN #359 L=0.00 PRINT. Sc359_LH {X=522502.51 Y=6930552.65} ROUTE THRU #359 L=5.90 GET. ROUTE THRU #358 L=2.00 ROUTE THRU #360 L=0.63 STORE. RAIN #360 L=0.00 PRINT. Sc360_LH {X=526991.11 Y=6933201.44} ROUTE THRU #360 L=2.13 GET. ROUTE THRU #360 L=2.66 ROUTE THRU #361 L=0.49 STORE. RAIN #361 L=0.00 PRINT. Sc361_LH {X=530775.09 Y=6933142.72} ROUTE THRU #361 L=1.38 GET. ROUTE THRU #361 L=1.79 GET. ROUTE THRU #361 L=2.05 PRINT. LOWER_OUT STORE. {END LOWER LOGAN URBS MODEL} {START BEHM CREEK URBS MODEL} RAIN #362 L=0.00 PRINT. Sc362_LH {X=529894.57 Y=6930786.96} ROUTE THRU #362 L=1.41 STORE. RAIN #363 L=0.00 PRINT. Sc363_LH {X=529404.55 Y=6929086.39} ROUTE THRU #363 L=1.37 GET. ROUTE THRU #364 L=0.79 STORE. RAIN #364 L=0.00 PRINT. Sc364_LH {X=531063.32 Y=6929357.46} GET. ROUTE THRU #364 L=1.16 ROUTE THRU #365 L=1.06 STORE. RAIN #365 L=0.00 PRINT. Sc365_LH {X=532709.16 Y=6928736.79} GET. ROUTE THRU #365 L=1.22 STORE. RAIN #366 L=0.00 PRINT. Sc366_LH {X=532865.80 Y=6930924.38} ROUTE THRU #366 L=0.98 ROUTE THRU #367 L=0.59 STORE. RAIN #367 L=0.00 PRINT. Sc367_LH {X=532410.37 Y=6929876.02} GET. ROUTE THRU #367 L=1.74 GET. ROUTE THRU #365 L=0.38 ROUTE THRU #368 L=0.85 STORE. RAIN #368 L=0.00 PRINT. Sc368_LH {X=534650.51 Y=6929077.45} GET. ROUTE THRU #368 L=0.86 PRINT. BEHM_CK_OUT GET. PRINT. DUMMY_OUT {END BEHM CREEK URBS MODEL} END OF CATCHMENT DATA. 27 RATING CURVES: LOCATION.CROFTBY LOCATION.BOONAH LOCATION.THE_OVERFLOW LOCATION.MAROON_HW LOCATION.FOREST_HOME LOCATION.RATHDOWNEY


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LOCATION.DIECKMANS_BR LOCATION.RUDDS_LANE LOCATION.ROUND_MOUNTAIN LOCATION.BEAUDESERT LOCATION.YARRAHAPPINI LOCATION.MACLEANS_BR LOCATION.FIRST_AV LOCATION.RESERVE_ LOCATION.LOGANLEA/WATERFORD = 0.0 LOCATION.LOGANLEA/WATERFORD = 7.0 LOCATION.LOGANLEA/WATERFORD = 13.5 LOCATION.BEENLEIGH LOCATION.RIEDEL_RD LOCATION.WOLFFDENE LOCATION.EAGLEBY LOCATION.WATERFORD LOCATION.LUMEAH LOCATION.BEAUD_PS LOCATION.BENOBBLE LOCATION.BROMFLEET LOCATION.WYARALONG END OF RATING CURVE DATA. 25 GAUGING STATIONS: LOCATION.CROFTBY LOCATION.BOONAH LOCATION.THE_OVERFLOW LOCATION.MAROON_HW LOCATION.FOREST_HOME LOCATION.RATHDOWNEY LOCATION.DIECKMANS_BR LOCATION.RUDDS_LANE LOCATION.ROUND_MOUNTAIN LOCATION.BEAUDESERT LOCATION.YARRAHAPPINI LOCATION.WOLFFDENE LOCATION.MACLEANS_BR LOCATION.WATERFORD LOCATION.FIRST_AV LOCATION.RESERVE_ LOCATION.LOGANLEA LOCATION.BEENLEIGH LOCATION.RIEDEL_RD LOCATION.EAGLEBY LOCATION.LUMEAH LOCATION.BEAUD_PS LOCATION.BENOBBLE LOCATION.BROMFLEET LOCATION.WYARALONG END OF GAUGING STATION DATA.


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16. Appendix C – Calibration and Verification Hydrographs

16.1 January 1974 calibration

Figure 24: Modelled and recorded discharge hydrographs at The Overflow (DNRM GS 145012a), January 1974 event

Figure 25: Modelled and recorded discharge hydrographs at the Round Mountain (DNRM GS 145008a), January 1974 event


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Figure 26: Modelled and recorded discharge hydrographs at the Yarrahappini (DNRM GS 145014a), January 1974 event

Figure 27: Modelled and recorded discharge hydrographs at the Broomfleet (DNRM GS 145102b), January 1974 event


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Figure 28: Modelled and recorded discharge hydrographs at the Wolffdene (DNRM GS 145196a), January 1974 event

Figure 29: Modelled and recorded discharge hydrographs at the Macleans Bridge (BOM GS 040935), February 1974 event


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Figure 30: Modelled and recorded discharge hydrographs at the Waterford (BOM GS 040878), January 1974 event

Figure 31: Modelled and recorded discharge hydrographs at the Rathdowney gauging station, January 1974 event


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16.2 April 1990 calibration

Figure 32: Modelled and recorded discharge hydrographs at The Overflow (DNRM GS 145012a), April 1990 event

Figure 33: Modelled and recorded discharge hydrographs at the Round Mountain (DNRM GS 145008a), April 1990 event


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Figure 34: Modelled and recorded discharge hydrographs at the Yarrahappini (DNRM GS 145014a), April 1990 event

Figure 35: Modelled and recorded discharge hydrographs at the Broomfleet (DNRM GS 145102b), April 1990 event


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Figure 36: Modelled and recorded discharge hydrographs at the Wolffdene (DNRM GS 145196a), April 1990 event

Figure 37: Modelled and recorded discharge hydrographs at the Macleans Bridge (BOM GS 040935), April 1990 event


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Figure 38: Modelled and recorded discharge hydrographs at the Waterford (BOM GS 040878), April 1990 event

\

Figure 39: Modelled and recorded discharge hydrographs at the Rathdowney gauging station, April 1990 event


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16.3 February 1991 calibration

Figure 40: Modelled and recorded discharge hydrographs at The Overflow (DNRM GS 145012a), February 1991 event

Figure 41: Modelled and recorded discharge hydrographs at the Round Mountain (DNRM GS 145008a), February 1991 event


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Figure 42: Modelled and recorded discharge hydrographs at the Yarrahappini (DNRM GS 145014a), February 1991 event

Figure 43: Modelled and recorded discharge hydrographs at the Broomfleet (DNRM GS 145102b), February 1991 event


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Figure 44: Modelled and recorded discharge hydrographs at the Wolffdene (DNRM GS 145196a), February 1991 event

Figure 45: Modelled and recorded discharge hydrographs at the Macleans Bridge (BOM GS 040935), February 1991 event


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Figure 46: Modelled and recorded discharge hydrographs at the Waterford (BOM GS 040878), February 1991 event

Figure 47: Modelled and recorded discharge hydrographs at the Rathdowney gauging station, February 1991 event


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Figure 48: Modelled and recorded discharge hydrographs at The Overflow (DNRM GS 145012a), January 2008 event



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Figure 53: Modelled and recorded discharge hydrographs at the Macleans Bridge (BOM GS 040935), January 2008 event


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Figure 56: Modelled and recorded discharge hydrographs at the The Overflow (DNRM GS 145012a), January 2013 event

Figure 57: Modelled and recorded discharge hydrographs at the Wyaralong Dam, January 2013 event


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16.6 May 1980 Verification

Figure 65: Modelled and recorded discharge hydrographs at The Overflow (DNRM GS 145012a), May 1980 event


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Figure 66: Modelled and recorded discharge hydrographs at the Round Mountain (DNRM GS 145008a), May 1980 event

Figure 67: Modelled and recorded discharge hydrographs at the Yarrahappini (DNRM GS 145014a), May 1980 event


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Figure 68: Modelled and recorded discharge hydrographs at the Broomfleet (DNRM GS 145102b), May 1980 event

Figure 69: Modelled and recorded discharge hydrographs at the Wolffdene (DNRM GS 145196a), May 1980 event


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Figure 70: Modelled and recorded discharge hydrographs at the Macleans Bridge (BOM GS 040935), May 1980 event

Figure 71: Modelled and recorded discharge hydrographs at the Waterford (BOM GS 040878), May 1980 event


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Figure 72: Modelled and recorded discharge hydrographs at the Rathdowney gauging station, May 1980 event

16.7 April 1988 Verification

Figure 73: Modelled and recorded discharge hydrographs at The Overflow (DNRM GS 145012a), April 1988 event


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Figure 74: Modelled and recorded discharge hydrographs at the Round Mountain (DNRM GS 145008a), April 1988 event

Figure 75: Modelled and recorded discharge hydrographs at the Yarrahappini (DNRM GS 145014a), April 1988 event


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Figure 76: Modelled and recorded discharge hydrographs at the Broomfleet (DNRM GS 145102b), April 1988 event

Figure 77: Modelled and recorded discharge hydrographs at the Wolffdene (DNRM GS 145196a), April 1988 event


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Figure 78: Modelled and recorded discharge hydrographs at the Macleans Bridge (BOM GS 040935), April 1988 event

Figure 79: Modelled and recorded discharge hydrographs at the Waterford (BOM GS 040878), April 1988 event


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Figure 80: Modelled and recorded discharge hydrographs at the Rathdowney gauging station, April 1988 event

16.8 March 2004 Verification

Figure 81: Modelled and recorded discharge hydrographs at the The Overflow (DNRM GS 145012a), March 2004 event


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Figure 82: Modelled and recorded discharge hydrographs at the Round Mountain (DNRM GS 145008a), March 2004 event

Figure 83: Modelled and recorded discharge hydrographs at the Yarrahappini (DNRM GS 145014a), March 2004 event


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Figure 84: Modelled and recorded discharge hydrographs at the Broomfleet (DNRM GS 145102b), March 2004 event

Figure 85: Modelled and recorded discharge hydrographs at the Wolffdene (DNRM GS 145196a), March 2004 event


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Figure 86: Modelled and recorded discharge hydrographs at the Macleans Bridge (BOM GS 040935), March 2004 event

Figure 87: Modelled and recorded discharge hydrographs at the Waterford (BOM GS 040878), March 2004 event


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Figure 88: Modelled and recorded discharge hydrographs at the Rathdowney gauging station, March 2004 event

16.9 January 2012 Verification

Figure 89: Modelled and recorded stage hydrographs at the Wyaralong Dam gauging station, January 2012 event


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17. Appendix D – Design Temporal Patterns

PERIOD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

30 MINUTE DURATION in 6 PERIODS OF 5 MINUTES

ARI<=30, WRMv7 13.9 26.6 20.2 15.6 12.4 11.3

ARI>30≤100, WRMv7 13.9 25.6 19.5 17 12 12

ARI>100, GSDM 20.3 23.3 20.3 17.7 12.4 6 1 HOUR DURATION in 12 PERIODS OF 5 MINUTES

ARI<=30, WRMv7 5.5 8.2 9.5 11 10.4 17.8 8 7.3 6.2 5.7 5.5 4.9

ARI>30≤100, WRMv7 5.9 7.5 8.4 11.3 11 17.7 7.9 6.6 6.2 6 5.8 5.7

ARI>100, GSDM 8 12.3 11.7 11.7 10.7 9.7 9.3 8.3 7.3 5 3.7 2.3 1.5 HOUR DURATION in 18 PERIODS OF 5 MINUTES

ARI<=30, WRMv7 3.4 4.8 6.7 7.3 12.1 8.2 6.1 6 5.7 5.3 4.3 5.2 4.4 4.4 4.2 4.1 4 3.8

ARI>30≤100, WRMv7 4.4 4.7 6.4 6.8 11 8.8 5.6 6.1 6 5.3 4.8 5.3 4.4 4.3 4.2 4.1 4 3.8

ARI>100, GSDM 4.7 7.1 8.6 7.8 7.8 7.8 7 7.6 5.8 6.6 5.6 5.6 5.1 3.9 3.3 2.3 2.2 1.2 3 HOUR DURATION in 12 PERIODS OF 15 MINUTES

ARI<=30, WRMv7 6.6 12.1 15.8 9.7 7.3 6.8 5.9 7.8 11.1 6.2 5.5 5.2

ARI>30≤100, WRMv7 7.2 11.7 15.8 9.1 7.5 7.1 6.4 7.4 10.5 6.1 5.9 5.3

ARI>100, GSDM 8 12.3 11.7 11.7 10.7 9.7 9.3 8.3 7.3 5 3.7 2.3 4.5 HOUR DURATION in 18 PERIODS OF 15 MINUTES

ARI<=30, WRMv7 8.8 6.1 4.5 7.1 4.8 5.5 3.5 7.5 11.7 8.6 4.6 3.2 4 3.7 3 4.6 5.2 3.6

ARI>30, WRMv7 7.7 6.6 4.7 7 4.9 5.6 4 6.5 10.9 7.9 4.8 4 3.9 3.7 3.4 4.9 5.6 3.9

ARI>100, GSDM 4.7 7.1 8.6 7.8 7.8 7.8 7 7.6 5.8 6.6 5.6 5.6 5.1 3.9 3.3 2.3 2.2 1.2 6 HOUR DURATION in 12 PERIODS OF 30 MINUTES

ARI<=30, WRMv7 5.8 6.1 7.3 9.6 17.2 6.6 13.5 7.7 6.4 4.5 9.9 5.4

ARI>30≤100, WRMv7 6.1 6.9 7.4 10.2 15.3 7.2 12.2 8.2 6.8 4.8 9.8 5.1

ARI>100, GSDM 8 12.3 11.7 11.7 10.7 9.7 9.3 8.3 7.3 5 3.7 2.3

9 HOUR DURATION in 18 PERIODS OF 30 MINUTES

ARI<=30, WRMv7 3.8 4.3 2.6 3.4 4.9 4.5 6.1 7.1 8.5 7.4 11.7 6.7 5.8 5.2 3.7 2.9 6.9 4.5

ARI>30≤100, WRMv7 3.7 4.4 3 3.8 5.6 4.5 5.8 6.9 8.2 7.2 11.2 6.7 5.7 5.4 4.1 2.9 6.9 4

ARI>100, GSDM GTSMR 4.7 7.1 8.6 7.8 7.8 7.8 7 7.6 5.8 6.6 5.6 5.6 5.1 3.9 3.3 2.4 2.1 1.2

12 HOUR DURATION in 24 PERIODS OF 30 MINUTES

ARI<=30, WRMv7 3.2 2.5 2.6 2.8 3.1 3.2 3.5 4.4 5.1 4 4.6 7.4 4.7 9.7 5.8 5.3 4.4 3.3 3.7 2.5 3 4.5 3.6 3.1

ARI>30, WRMv7 3.3 2.5 2.8 3.3 3.9 3.5 3.8 4.2 4.7 3.8 4.7 7.2 4.4 9.5 5.5 4.9 4.4 3.8 3.8 2.5 3.1 4.2 3.3 2.9

ARI>100, GSDM GTSMR 3.3 4.7 6 6.3 5.8 5.8 5.8 5.8 5.3 5.3 5.5 4.2 5 4.3 4.2 4.2 4 3.3 2.5 2.5 2 1.7 1.7 0.8

18 HOUR DURATION in 18 PERIODS OF 1 HOUR

ARI<=30, WRMv7 3.5 2.7 2.3 4.7 4.9 7.1 9 14.4 5 7.8 7 5.7 6.3 5.2 4.2 3.4 3.9 2.9

ARI>30≤100, WRMv7 3.6 2.7 2.2 4.8 5.2 6.8 9.5 14 5 7.6 6.7 4.8 6.5 5.2 4.4 3.7 4.2 3.1

ARI>100, GSDM GTSMR 3.9 3.9 3.2 3 5.3 7.6 8.5 11.1 11.1 5.3 5.3 3 2.2 4.4 6.5 6.1 4.8 4.8

24 HOUR DURATION in 24 PERIODS OF 1 HOUR

ARI<=30, WRMv7 3.3 2 2.5 2 2.4 3.8 4.9 5.4 3.8 5.1 6.1 6.8 11.5 3.1 6.5 7.9 4.2 3.6 2.6 3 2.4 3.4 2 1.7

ARI>30≤100, WRMv7 3.4 1.7 2.5 1.9 2.5 3.6 5.1 5.5 3.4 5.3 6.2 6.9 12.2 3 6.4 7.8 3.7 3.4 2.4 2.9 2.2 3.3 2.5 2.2

ARI>100, GTSMR 2.9 2.9 2.9 2.3 2.3 2.3 5.7 5.7 5.7 8.3 8.3 8.3 4 4 4 1.6 1.6 1.6 4.9 4.9 4.9 3.7 3.6 3.6

36 HOUR DURATION in 18 PERIODS OF 2 HOURS

ARI<=30, WRMv7 3.5 2.5 2.8 3.4 3.6 6.9 4 4.7 5.8 3.4 15.2 8.9 7.7 11.8 5.9 3.7 3.4 2.8

ARI>30, WRMv7 3.9 3.1 2.8 3.6 3.2 6.5 3.6 4.3 5.9 3.6 14.3 9.9 8.3 10.9 6.5 3.7 3.2 2.7

ARI>100, GTSMR 4.8 3.4 2 3.5 3.3 3.1 6.2 5 3.8 6.7 9.3 12 7.7 5.6 3.6 8.3 6.6 5.1


ARI<=30, WRMv7 2.4 2.2 2.3 2.3 3.2 3.4 2.5 3.6 2.7 3.7 3.5 5.5 13.5 8.9 6.2 3.4 5.3 8.7 3.5 4.1 2.8 2.3 2 2

ARI>30≤100, WRMv7 2.8 2.5 2.4 2.1 3 3.2 2.1 3.6 2.7 3.5 3.5 5.8 11.8 9.3 6.7 4.1 5.9 8.6 3.3 4.1 2.5 2.3 2.1 2.1

ARI>100, GTSMR 1.5 2 2.5 4.3 4 3.8 10.3 6.9 3.4 2.5 4 5.4 2.9 2.3 1.7 1.1 3.5 5.9 6.4 6.9 7.3 5.1 4 2.3


ARI<=30, WRMv7 6.3 2.9 4.2 7.3 4.7 3.4 9.2 11.7 16.8 6.1 4.2 3.9 3.9 3.4 3.2 3.1 2.9 2.8

ARI>30≤100, WRMv7 6.5 3.4 4.2 6.7 4.5 3.3 8 11.1 16.9 6.8 4.8 3.9 3.8 3.5 3.4 3.3 3 2.9

ARI>100, GTSMR 3.25 7.54 5.71 5.1 8.25 9.89 6.31 8.49 8.64 4.42 2.33 4.82 2.98 2.86 11.45 2.98 2.03 2.95


ARI<=30, GTSMR 1.79 1.07 3.21 1.92 4.37 4.03 5.6 6.77 3.39 2.97 1.34 4.75 5.82 7.98 6.2 3.85 0.45 0.82 2.18 2.79 2.35 2.52 5.26 3.57 2.11 1.76 1.48 1.08 2.71 2.03 2.57 1.26


PERIOD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

ARI>30≤100, GTSMR 1.79 1.07 3.21 1.92 4.37 4.03 5.6 6.77 3.39 2.97 1.34 4.75 5.82 7.98 6.2 3.85 0.45 0.82 2.18 2.79 2.35 2.52 5.26 3.57 2.11 1.76 1.48 1.08 2.71 2.03 2.57 1.26

ARI>100, GTSMR 1.79 1.07 3.21 1.92 4.37 4.03 5.6 6.77 3.39 2.97 1.34 4.75 5.82 7.98 6.2 3.85 0.45 0.82 2.18 2.79 2.35 2.52 5.26 3.57 2.11 1.76 1.48 1.08 2.71 2.03 2.57 1.26


ARI<=30, GTSMR 1.44 0.45 0.73 0.65 2.1 3.57 2.57 1.01 1.93 6.73 1.82 1.64 1.53 2.74 2.52 4.72 7.39 9.39 3.07 2.44 5.48 1.32 0.26 0.9 1.37 5.08 1.06 3.33 4.21 2.25 1.2 0.53 2.94 3.79 6.17 0.43 0.16 0.12 0.37 0.59

ARI>30≤100, GTSMR 1.44 0.45 0.73 0.65 2.1 3.57 2.57 1.01 1.93 6.73 1.82 1.64 1.53 2.74 2.52 4.72 7.39 9.39 3.07 2.44 5.48 1.32 0.26 0.9 1.37 5.08 1.06 3.33 4.21 2.25 1.2 0.53 2.94 3.79 6.17 0.43 0.16 0.12 0.37 0.59

ARI>100, GTSMR 1.44 0.45 0.73 0.65 2.1 3.57 2.57 1.01 1.93 6.73 1.82 1.64 1.53 2.74 2.52 4.72 7.39 9.39 3.07 2.44 5.48 1.32 0.26 0.9 1.37 5.08 1.06 3.33 4.21 2.25 1.2 0.53 2.94 3.79 6.17 0.43 0.16 0.12 0.37 0.59

PERIOD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40


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18. Appendix E – Design Event Hydrographs

Figure 97: Frequent to large event hydrographs, Teviot Brook at The Overflow

Figure 98: Extreme design event hydrographs, Teviot Brook at The Overflow


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Figure 99: Frequent to large design event hydrographs, Logan River at Round Mountain

Figure 100: Extreme design event hydrographs, Logan River at Round Mountain


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Figure 101: Frequent to large design event hydrographs, Logan River at Yarrahappini

Figure 102: Extreme design event hydrographs, Logan River at Yarrahappini


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Figure 103: Frequent to large design event hydrographs, Albert River at Broomfleet

Figure 104: Extreme design event hydrographs, Albert River at Broomfleet


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Figure 105: Frequent to large design event hydrographs, Albert River at Wolffdene

Figure 106: Extreme design event hydrographs, Albert River at Wolffdene


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Figure 107: Frequent to large design event hydrographs, Logan River at Macleans Bridge

Figure 108: Extreme design event hydrographs, Logan River at Macleans Bridge


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Figure 109: Frequent to large design event hydrographs, Logan River at Waterford

Figure 110: Extreme design event hydrographs, Logan River at Waterford


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19. Appendix F – Monte Carlo Results

The design discharge estimates in the Table 47 to Table 49 include an Areal Reduction Factors

(ARF) based on total catchment area.

Table 47 - URBS model estimated peak design discharges from DEA and TPT approach at The Overflow, Teviot Brook

ARI (years)


DEA TPT

2 169 397

5 379 557

10 592 666

20 819 805

50 1077 996

100 1288 1139

200 1453 1307

500 1681 1564

1000 1878 1747

2000 2102 2112

Table 48 - URBS model estimated peak design discharges from DEA and TPT approach, Logan River at Round Mountain and Yarrahappini

ARI (years)



DEA TPT DEA TPT

2 473 1054 512 1411

5 1053 1490 1228 1995

10 1572 1803 2062 2432

20 2176 2154 2890 2943

50 2817 2644 3918 3677

100 3350 3038 4752 4162

200 3747 3404 5273 4770

500 4287 4018 6071 5661

1000 4826 4541 6927 6499

2000 5471 5456 7938 8006


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Table 49 - URBS model estimated peak design discharges from DEA and TPT approach, Albert River at Bromfleet and Wolffdene

ARI (years)


Bromfleet Wolffdene

DEA TPT DEA TPT

2 282 594 321 711

5 669 886 801 1066

10 997 1087 1214 1314

20 1328 1320 1612 1548

50 1720 1619 2111 1923

100 2036 1849 2503 2174

200 2295 2077 2826 2517

500 2674 2477 3271 3028

1000 2910 2728 3616 3296

2000 3244 3220 4029 3927


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Logan River Catchment Hydrological Study...and rainfall spatial distribution and design rainfall losses) adopted in the study are based on a comprehensive review of the latest available