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Logan River Catchment

Hydrological Study Addendum Report July 2015

TRACKS-#50056335-v2-LOGAN_RIVER_HYDROLOGICAL_STUDY_ADDENDUM_REPORT_JULY_2015 of 31

Title: Logan River Catchment Hydrological Study

- Addendum Report 2015

Author:

Study for: City Planning Branch

Planning and Environment Directorate

The City of Gold Coast

File Reference: WF15/44/02 (P6)

TRACKS #50056335

Version history

Version Comments/Change Changed by

& date Reviewed by &

date

1.0 Adoption of BOM’s new IFD 2013

2.0 Grammar Review

Distribution list

Name Title Directorate Branch

NH Team PE City Planning


1. Executive Summary

The City of Gold Coast (City) undertook a hydrological study for Logan River catchment in December 2014 (City 2014, Ref 1). In the study, the Logan River catchment hydrological model was developed using the URBS modelling software. The model was calibrated to five historical flood events and verified against another four flood events. The design rainfalls from 2 to 2000 year ARIs of the study were based on a study undertaken by Australian Water Engineering (AWE) in 1992 and CRC-FORGE. In early 2015, The Bureau of Meteorology (BOM) released new IFD (2013) design rainfalls as part of the revision of Engineers Australia’s design handbook ‘Australian Rainfall and Runoff: A Guide to Flood Estimation’. In July 2015, the 2014 calibrated Logan hydrological model was used to run the design events using rainfall data obtained from the BOM’s new IFD tables 2013. This report documents the review of the City 2014 model and should be read in conjunction with the City 2014 hydrological report.

The original forest factor, catchment and channel parameters obtained from the 2014 calibrated Logan hydrological model were used for this study update. The table below shows these parameter values:

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

The BOM’s new (IFD 2013) rainfalls were adopted for all durations and ARIs less than and equal to 100 years. For the ARIs greater than 100 year to 2000 year:

The extrapolated BOM rainfalls are used for durations less than 24 hours.

The maximum intensity of BOM’s new IFD 2013 and CRC-FORGE is adopted for durations greater than and equal to 24 hours.

The URBS model was used to estimate design discharges for (i) a range of design events from 2 to 2000 year ARIs, (ii) the Probable Maximum Precipitation Flood (PMPDF) and (iii) the Probable Maximum Flood (PMF) with the adopted rainfalls and rainfall losses obtained from the Flood Frequency Analysis (FFA) of this study. The table below shows the URBS estimated design discharges from the current study and City 2014 study including differences for a range of return periods up to PMF at Wolffdene and Yarrahappini gauging stations. All the design discharges presented in the table include an Areal Reduction Factor (ARF) based on the total catchment area. Design discharges for other gauging stations are given in section 3.5 . Although the table shows that differences of design discharge estimates between the two studies range from approximately – 9 to +11 % for the Wolffdene gauging station, the flood frequency analysis shows better results for some of the return periods.


ARI

(years)

Estimated Peak Design Discharge (m3/s)*

Wolffdene Yarrahappini

Current Study

City 2014

Study

% increased / decreased

Current Study

City 2014

Study

% increased / decreased

2 355 321 (+) 11 538 512 (+) 5

5 740 801 (-) 8 1242 1228 (+) 1

10 1103 1214 (-) 9 2000 2062 (-) 3

20 1493 1612 (-) 7 2879 2890 0

50 1952 2111 (-) 8 3862 3918 (-) 1

100 2360 2503 (-) 6 4769 4752 0

200 2960 2826 (+) 5 5579 5273 (+) 6

500 3467 3271 (+) 6 6534 6071 (+) 8

1000 3884 3616 (+) 7 7390 6927 (+) 7

2000 4330 4029 (+) 7 8308 7938 (+) 5

PMPDF 7846 7919 (- )1 17944 18238 (-) 2

PMF 8019 8137 (-) 1 19569 19915 (-) 2

The model estimated peak discharges were compared with the equivalent values obtained from the FFA. The design discharge estimates to the FFA are generally good as compare to the City 2014 study. The table below shows design discharges obtained from FFA, current and City 2014 studies.

ARI (years)

Estimated Peak Design Discharge (m3/s)*

Wolffdene Yarrahappini

FFA Current

Study

City

(2014). FFA Current

Study

City

(2014).

2 164 405 379 572 564 542

5 652 818 887 1092 1290 1284

10 1067 1199 1313 1580 2061 2122

20 1511 1608 1738 2212 2945 2960

50 2131 2093 2254 3369 3942 3994

100 2615 2533 2667 4579 4863 4838

Note:* includes an Areal Reduction Factor (ARF) based on area upstream of respective gauging stations

The Monte Carlo simulations were undertaken in this study for comparative purposes only. Both the Total Probability Theorem (TPT) and the Cooperative Research Centre – Catchment Hydrology (CRC-CH) Monte Carlo techniques were applied for design discharge estimates. These techniques are collectively known as the Joint Probability Approach (JPA). The figures below show the comparison of design discharges at Yarrahappini and Wolffdene for Design Event Approach (DEA)


and the JPA modelling approach. Comparison of design discharges at other locations is given in Section 4. The figures show the TPT approach generated average results for the Logan River Catchment. Additional background work would be required for this catchment to use the CRC-CH technique with confidence.

The updated URBS model design discharges were compared with the previous study’s results and successfully reconciled with FFA estimates at five gauging stations and verified with the Monte Carlo Simulation. It is concluded that the Joint Probability Approach (Monte Carlo) supports the URBS model design discharge estimates.


Table of Contents 1. Executive Summary ...................................................................................................................... 3

2. Introduction ................................................................................................................................... 7

3. Project Details ............................................................................................................................... 7

3.1 Adopted Model parameters ................................................................................................. 7

3.2 Rainfall Intensity .................................................................................................................. 7

3.3 Rainfall Losses .................................................................................................................... 8

3.4 Flood Frequency Analysis (FFA) ......................................................................................... 8

3.5 Design Flood Estimation .................................................................................................... 15

Frequent to Large Design Events (up to including 100 years ARI) .......................... 15 3.5.1

Rare to Extreme Design Events (200 to 2000 years ARI) ........................................ 17 3.5.2

Probable Maximum Precipitation Design Flood (PMPDF) ........................................ 19 3.5.3

Probable Maximum Flood (PMF) .............................................................................. 20 3.5.4

4. Joint Probability Approach (Monte Carlo Simulation) ............................................................. 21

5. Conclusion ................................................................................................................................... 25

6. References ................................................................................................................................... 26

7. Appendices .................................................................................................................................. 27

Appendix A - Intensity-Frequency-Duration Curves (IFD) .......................................................... 27

Appendix B – Monte Carlo Results ............................................................................................. 29


2. Introduction

City developed a URBS hydrological model for the Logan River catchment in December 2014 (Ref 1). The model was calibrated against January 1974, April 1990, February 1991, January 2008 and January 2013 historical flood events and was verified against May 1980, April 1988, March 2004 and January 2012 flood events. The design rainfalls from 2 to 500 year ARIs of the study were based on a study undertaken by Australian Water Engineering (AWE) in 1992 (Ref 2) and CRC-FORGE (Ref 4). In early 2015, the Bureau of Meteorology (BOM) released a new IFD (2013) design rainfalls as part of the revision of Engineers Australia’s design handbook ‘Australian Rainfall and Runoff: A Guide to Flood Estimation’ (Ref 3). The revision of temporal patterns, areal reduction factors and losses are yet to be released.

In July 2015, the 2014 calibrated Logan hydrological model was used to run all the design events using rainfalls obtained from the BOM’s new IFD 2013 tables. The other design parameters e.g. temporal patterns and areal reduction factors were used in accordance with City 2014 study (Ref 1).

This addendum needs to be read in-conjunction with the original report of Logan River Catchment Hydrological Study, December 2014 (Ref 1).

3. Project Details

3.1 Adopted Model parameters

As mentioned, the 2014 calibrated Logan River Hydrological model is used for this study. Table 1 shows adopted global catchment and channel parameters.

Table 1 - Adopted catchment and channel parameters (source: City 2014 – Ref 1)

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

3.2 Rainfall Intensity

The methodologies used in this study to use the new IFD 2013 tables are:

The new BOM IFD tables are transformed to ARI’s and extrapolated to ARI 2000 using a fitted GEV distribution, as used by BOM.

The new rainfall intensities are adopted for all ARIs less than and equal to 100 years for all durations.

For ARIs greater than 100 and up to 2000 years:

o The extrapolated BOM rainfalls are used for durations less than 24 hours.

o The maximum intensity of BOM’s new IFD 2013 and CRC-FORGE is adopted for durations greater than and equal to 24 hours.


The design rainfall intensities were extracted at the centroid of each individual sub catchment.

The above approach was adopted based on an internal review and peer reviewer recommendations. Appendix-A (Figure A. 1 to Figure A. 4) shows examples of adopted intensity-frequency-duration curves at upper, middle and lower regions of the Logan River catchment.

3.3 Rainfall Losses

The initial loss (IL) and continuing loss (CL) method of accounting for rainfall losses were 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 2 shows the final ILs and CLs for the Logan River catchment for all ARIs up to and including the 100 year ARI event.

Table 2 - Adopted initial and continuing loss values

ARI (Years)

Adopted Losses

City 2014 Study (Ref 1) Current Study (July 2015)

Initial Loss

(mm)

Continuing Loss

(mm/hour)

Initial Loss

(mm)

Continuing Loss

(mm/hour)

2 20 3.0 20 2.25

5 15 2.0 15 1.9

10 10 1.2 10 1.5

20 0 0.8 0 1.1

50 0 0.4 0 0.9

100 0 0.1 0 0.6

Note: Same initial losses are adopted for both City 2014 and current studies

The initial and continuing losses adopted for the 100 year ARI were also adopted for all ARIs greater than 100 year as per City 2014 study.

3.4 Flood Frequency Analysis (FFA)

The URBS model was used to run the design events with the adopted parameters and design rainfalls obtained from the BOM’s new IFD 2013 tables. The model estimated design discharges were compared with the design peak discharges obtained from the Flood Frequency Analysis (FFA). A Log Pearson Type III Distribution was fitted to the discharge data at the Overflow, Round Mountain, Yarrahappini, Bromfleet and Wolffdene gauging stations. Figure 1 to Figure 5 show the FFA plot and Table 4 to Table 8 show the estimated design discharges from the current (July 2015) and the City 2014 (Ref 1) studies at the five gauging stations. For this comparison, the Aerial Reduction Factor (ARF) for design event simulations were calculated based on the catchment area upstream of each particular gauging station (Table 3). The design discharge estimates are generally reasonable compared to FFA and the City 2014 study, with some over/underestimates at the five gauging stations for some of the ARIs. The following is of note with regards to URBS discharge estimates:

The URBS overestimated flood to FFA at all gauging stations for ARIs 2 to 20 year in both City 2014 and this study.


The model overestimated flood to FFA at Yarrahappini and Round Mountain for the ARIs 50 and 100 year in both City 2014 and this study.

The model underestimated flood to FFA by 8% at The Overflow, 3 to 4% at Bromfleet and 1 to 3% at Wolffdene for the 50 and 100 years ARIs in this study. This is because of rainfall variations in upper and lower reaches of Logan and Albert River catchments in BOM’s new IFD, and the single set of model parameters and losses used for the model simulation.

Table 3 - Area upstream of gauging stations

Gauging Station Stream Name

Area* (km2) Available Annual Peak Flood (no of

years) for FFA

No of low flows omitted from FFA

The Overflow Teviot Brook 502 36 3

Round Mountain Logan River 1264 43 1

Yarrahappini Logan River 2419 34 9

Bromfleet Albert River 544 78 6

Wolffdene Albert River 721 33 3

* Upstream of gauging station, km2 - kilometres


Figure 1: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Teviot Brook at The Overflow (145012a)

Table 4 - Comparison of URBS model and FFA estimated peak design discharges at The Overflow, Teviot

Brook

ARI (years)

Estimated Peak Design Discharge (m3/s)

FFA Current Study City (2014).

Logan River

2 86 201 209

5 336 397 440

10 566 595 666

20 815 828 909

50 1159 1067 1183

100 1421 1295 1404


Figure 2: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Logan River at Round Mountain (145008a)

Table 5 - Comparison of URBS model and FFA estimated peak design discharges at Round Mountain, Logan River

ARI (years)



Logan River

2 453 531 537

5 1083 1123 1151

10 1560 1695 1691

20 2023 2341 2318

50 2606 3067 2971

100 3018 3734 3515


Figure 3: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Logan River at Yarrahappini (145014a)

Table 6 - Comparison of URBS model and FFA estimated peak design discharges at Yarrahappini, Logan

River

ARI (years)



Logan River

2 572 564 542

5 1092 1290 1284

10 1580 2061 2122

20 2212 2945 2960

50 3369 3942 3994

100 4579 4863 4838


Figure 4: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Albert River at Bromfleet (145102b)

Table 7 - Comparison of URBS model and FFA estimated peak design discharges at Bromfleet, Albert River

ARI (years)



Logan River

2 286 351 341

5 672 695 764

10 985 1006 1094

20 1325 1356 1465

50 1819 1762 1877

100 2227 2131 2213


Figure 5: Comparison of URBS Model Design Discharges and Flood Frequency Distribution, Albert River at Wolffdene

Table 8 - Comparison of URBS model and FFA estimated peak design discharges at Wolffdene, Albert River

ARI (years)



Logan River

2 164 405 379

5 652 818 887

10 1067 1199 1313

20 1511 1608 1738

50 2131 2093 2254

100 2615 2533 2667


3.5 Design Flood Estimation

Frequent to Large Design Events (up to including 100 years ARI) 3.5.1

The URBS model was simulated for storm durations 1, 1.5, 3, 6, 9, 12, 18, 24, 36, 48, 72, 96 and 120 hours for a range of ARIs from 2 to 100 year with the BOM’s new 2013 IFD tables together with design losses obtained through FFA (Table 2). The Aerial Reduction Factor (ARF) for these simulations was calculated based on total catchment area (3878 km2). Table 9 and Table 10 show URBS estimated design discharges and critical storm durations for up to and including the 100 years ARIs.

Table 9 - URBS Model Predicted Design Discharges, 2 to 100 year ARI events

(Comparable to Table 29 of City 2014 study report)

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 33 73 111 159 205 247

Boonah Teviot Brook 123 256 385 550 706 851

The Overflow Teviot Brook 164 340 525 742 969 1184

Wyaralong Dam In

Teviot Brook 168 352 548 771 1017 1245

Wyaralong Dam Out

Teviot Brook 81 222 397 609 838 1069

Forest Home Logan River 82 178 269 377 493 598

Rathdowney Logan River 194 432 668 937 1222 1487

Dieckmans Bridge

Running Creek 100 194 277 373 490 594

Rudds Lane Christmas

Creek 108 218 319 440 579 705

Round Mountain

Logan River 479 1040 1592 2197 2898 3520

Beaudesert Logan River 469 1028 1600 2231 2944 3587

Yarrahappini Logan River 538 1242 2000 2879 3862 4769

Macleans Bridge

Logan River 516 1145 1830 2628 3461 4210

Waterford Logan River 486 1085 1760 2547 3361 4097

First Ave Scrubby Creek 63 111 153 204 255 301

Reserve Park Slacks Creek 36 57 77 102 125 145

Loganlea Slacks Creek 86 147 201 260 331 394

Eagleby Logan River 482 1077 1749 2533 3345 4078

Lumeah #2 Albert River 108 216 314 428 562 682

Benobble Canungra

Creek 88 170 242 323 425 514

Bromfleet Albert River 302 622 916 1232 1613 1947

Wolffdene Albert River 355 740 1103 1493 1952 2360

Beenleigh Albert River 360 753 1123 1525 1993 2412

Riedel Road Logan River 575 1206 1853 2664 3582 4469

Logan River Mouth

Logan River 587 1236 1912 2706 3597 4521


Table 10 - 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 12 18 36 18 36 36

Wyaralong Dam IN

Teviot Brook 12 18 36 18 36 36

Wyaralong Dam Out

Teviot Brook 12 36 36 36 36 36

Forest Home Logan River 36 36 36 9 9 24

Rathdowney Logan River 36 36 36 9 9 24

Dieckmans Bridge

Running Creek 36 36 36 24 24 24


Creek 36 24 24 9 9 9

Round Mountain

Logan River 36 36 36 36 36 36

Beaudesert Logan River 36 36 36 36 36 36

Yarrahappini Logan River 36 36 36 48 48 48

Macleans Bridge

Logan River 36 36 36 48 48 48

Waterford Logan River 36 36 48 48 48 48

First Ave Scrubby Creek 12 9 9 9 9 9

Reserve Park Slacks Creek 9 3 3 3 3 3

Loganlea Slacks Creek 36 36 36 24 36 36

Eagleby Logan River 36 36 48 48 48 48

Lumeah #2 Albert River 36 36 24 24 24 24

Benobble Canungra

Creek 36 36 36 24 24 24

Bromfleet Albert River 36 36 36 36 36 36

Wolffdene Albert River 36 36 36 36 36 36

Beenleigh Albert River 36 36 36 36 36 36

Riedel Road Logan River 36 36 48 72 72 72

Logan River Mouth

Logan River 36 48 48 48 48 120


Rare to Extreme Design Events (200 to 2000 years ARI) 3.5.2

The URBS model was simulated for storm durations 1, 1.5, 3, 6, 9, 12, 18, 24, 36, 48, 72, 96 and 120 hours for a range of ARIs from 200 to 2000 year with the blended BOM’s new IFD 2013 tables and CRC-FORGE (Section 3.2 ) curves and new losses obtained from this study (Section 3.3 ). The Areal Reduction Factor (ARF) for these simulations was calculated based on total catchment area (3878 km2). Table 11 and Table 12 show URBS estimated design discharges and critical storm durations for 200 to 2000 year ARIs.

Table 11 - 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 288 342 386 435

Boonah Teviot Brook 994 1180 1334 1505

The Overflow Teviot Brook 1380 1626 1833 2056

Wyaralong Dam In

Teviot Brook 1450 1712 1933 2171

Wyaralong Dam Out

Teviot Brook 1274 1544 1765 2006

Forest Home Logan River 702 836 956 1090

Rathdowney Logan River 1779 2122 2407 2723

Dieckmans Bridge

Running Creek 686 837 964 1105


Creek 827 1007 1160 1331

Round Mountain

Logan River 4124 4842 5458 6203

Beaudesert Logan River 4217 4968 5591 6264

Yarrahappini Logan River 5579 6534 7390 8308

Macleans Bridge

Logan River 4882 5655 6282 6950

Waterford Logan River 4761 5531 6158 6827

First Ave Scrubby Creek 362 423 474 528

Reserve Park Slacks Creek 165 195 219 245

Loganlea Slacks Creek 453 528 591 658

Eagleby Logan River 4742 5511 6138 6878

Lumeah #2 Albert River 832 976 1097 1249

Benobble Canungra

Creek 593 706 812 931

Bromfleet Albert River 2445 2851 3182 3534

Wolffdene Albert River 2960 3467 3884 4330

Beenleigh Albert River 3023 3547 3980 4441

Riedel Road Logan River 5301 6352 7267 8273

Logan River Mouth

Logan River 5419 6534 7477 8515


Table 12 - 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 9

Boonah Teviot Brook 12 12 12 12

The Overflow Teviot Brook 36 36 36 36

Wyaralong Dam In

Teviot Brook 36.0 36.0 36.0 36.0

Wyaralong Dam Out

Teviot Brook 36 36 36 36

Forest Home Logan River 9 9 9 9

Rathdowney Logan River 9 9 9 9

Dieckmans Bridge

Running Creek 12 12 12 12


Creek 9 9 9 9

Round Mountain

Logan River 36 36 18 12

Beaudesert Logan River 36 36 36 36

Yarrahappini Logan River 48 36 36 36

Macleans Bridge

Logan River 48 48 48 48

Waterford Logan River 48 48 48 72

First Ave Scrubby Creek 9 9 9 9

Reserve Park Slacks Creek 3 3 3 3

Loganlea Slacks Creek 36 36 36 36

Eagleby Logan River 48 48 48 72

Lumeah #2 Albert River 24 24 12 12

Benobble Canungra

Creek 24 24 12 12

Bromfleet Albert River 36 36 36 36

Wolffdene Albert River 36 36 36 36

Beenleigh Albert River 36 36 36 36

Riedel Road Logan River 72 120 120 120

Logan River Mouth

Logan River 120 120 120 120


Probable Maximum Precipitation Design Flood (PMPDF) 3.5.3

The calibrated model obtained from City 2014 study (Ref 1) was simulated for PMPDF with the rainfall losses adopted for this study. Table 13 shows the URBS model predicted peak PMP Design Flood (PMPDF) discharges and critical durations at key locations throughout the Logan River catchment. To estimate PMPDF discharges, the URBS model was run for all storm durations from 12 to 120 hours. The URBS estimated slightly lower design discharges for PMPDF than the City 2014 study because the adopted rainfall losses are higher in this study than in the City 2014 study.

Table 13 - 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 1755 12

Boonah Teviot Brook 4999 12

The Overflow Teviot Brook 6004 12

Wyaralong Dam In

Teviot Brook 6080 12

Wyaralong Dam Out

Teviot Brook 5587 12

Forest Home Logan River 2671 12

Rathdowney Logan River 7615 12

Dieckmans Bridge

Running Creek 2163 12


Creek 2696 12

Round Mountain

Logan River 15016 12

Beaudesert Logan River 14241 12

Yarrahappini Logan River 17944 24

Macleans Bridge


Waterford Logan River 13111 72

First Ave Scrubby Creek 1101 12

Reserve Park Slacks Creek 438 12

Loganlea Slacks Creek 1486 12

Eagleby Logan River 13506 120

Lumeah #2 Albert River 2524 12

Benobble Canungra

Creek 1779 12

Bromfleet Albert River 7026 12

Wolffdene Albert River 7846 12

Beenleigh Albert River 7851 12

Riedel Road Logan River 16927 120

Logan River Mouth



Probable Maximum Flood (PMF) 3.5.4

The calibrated model obtained from City 2014 study (Ref 1) was simulated for PMF with the rainfall losses adopted for this study. Table 14 shows the URBS model predicted peak PMF discharges and critical durations at key locations throughout the Logan River catchment. To estimate PMF discharges, the URBS model was run for storm durations from 24 hours to 120 hours for the top ten individual storm temporal patterns. The URBS estimated slightly lower design discharges for PMF than for the City 2014 study because the adopted rainfall losses are higher in this study than in the City 2014 study.

Table 14 - 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 1808 24 1982JAN20-5

Boonah Teviot Brook 4787 24 1982JAN20-5

The Overflow Teviot Brook 5865 24 1982JAN20-5

Wyaralong Dam In

Teviot Brook 6057 24 1982JAN20-5

Wyaralong Dam Out

Teviot Brook 5690 24 1982JAN20-5

Forest Home Logan River 2934 24 1982JAN20-5

Rathdowney Logan River 7674 24 1976FEB09-2

Dieckmans Bridge

Running Creek 2349 24 1982JAN20-5


Creek 2810 24 1982JAN20-5

Round Mountain

Logan River 14654 24 1982JAN20-5

Beaudesert Logan River 14476 24 1982JAN20-5

Yarrahappini Logan River 19569 36 1954FEB21-2

Macleans Bridge

Logan River 13961 36 1954FEB21-2

Waterford Logan River 13990 96 1974JAN28-4

First Ave Scrubby Creek 1063 24 1982JAN20-5

Reserve Park Slacks Creek 488 24 1982JAN20-5

Loganlea Slacks Creek 1476 24 1976FEB09-2

Eagleby Logan River 14489 96 1998MAR05-7

Lumeah #2 Albert River 2415 24 1982JAN20-5

Benobble Canungra

Creek 1731 24 1982JAN20-5

Bromfleet Albert River 6787 24 1976FEB09-2

Wolffdene Albert River 8019 36 1954FEB21-2

Beenleigh Albert River 8235 36 1954FEB21-2

Riedel Road Logan River 18102 72 1995FEB28-4

Logan River Mouth

Logan River 18162 72 1995FEB28-4


4. Joint Probability Approach (Monte Carlo Simulation)

The Monte Carlo simulation has been undertaken for comparative purpose only, with the Design Event Approach (DEA). Both the Total Probability Theorem (TPT) and Cooperative Research Centre – Catchment Hydrology (CRC-CH) Monte Carlo techniques have been applied in this study. Figure 6 to Figure 12 show comparison of design discharges at different locations from the DEA and Joint Probability Approach (JPA). The TPT approach had generated average results for the Logan River Catchment and additional background work would be required for this catchment to use the CRC-CH technique with confidence. URBS estimated design discharges from DEA and Monte Carlo are given in Appendix B (Table B. 1 to Table B. 3).

Figure 6: Comparison of design discharge estimates from DEA and JPA approach, Logan River at the Round Mountain


Figure 7: Comparison of design discharge estimates from DEA and JPA approach, Logan River at the Yarrahappini

Figure 8: Comparison of design discharge estimates from DEA and JPA approach, Logan River at the Macleans Bridge


Figure 9: Comparison of design discharge estimates from DEA and JPA approach, Logan River at the Waterford

Figure 10: Comparison of design discharge estimates from DEA and JPA approach, Albert River at the Bromfleet


Figure 11: Comparison of design discharge estimates from DEA and JPA approach, Albert River at the Wolffdene

Figure 12: Comparison of design discharge estimates from DEA and JPA approach, Teivot Brook at the Overflow


5. Conclusion

The City 2014 (Ref 1) calibrated Logan hydrological model was used to rerun the design events from 2 to 100 year ARIs using rainfall obtained from the BOM’s new IFD 2013 tables. The model was also simulated for the 200 to 2000 year ARIs with blended IFD between the BOM’s new IFD and CRC-FORGE (refer Section 3.2 ). The PMPDF and PMF discharges were re-estimated using rainfall losses obtained from this study.

Flood Frequency Analysis (FFA) for peak annual discharges were undertaken at The Overflow, Round Mountain, Yarrahappini, Bromfleet and Wolffdene gauging stations. The model design discharges were compared and successfully reconciled with FFA estimates at five key gauging stations. Monte Carlo simulations were undertaken to verify the results of the Design Event Approach.

This addendum report should be read in-conjunction with the original report of Logan River catchment Hydrological Study, December 2014 (City 2014).


6. References

1. City (2014). Logan River Catchment Hydrological Study, December 2014. Report prepared by the City Of Gold Coast. TRACKS-#45737331-LOGAN_RIVER_HYDROLOGICAL_STUDY_DECEMBER_2014

2. AWE (1992). Logan River Floodplain Filling Study. Report prepared by Australian Water Engineering, November 1992.

3. IEAust. Australian Rainfall and Runoff: A Guide to Flood Estimation (Australian Rainfall and Runoff: A Guide to Flood Estimation)

4. (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


7. Appendices

Appendix A - Intensity-Frequency-Duration Curves (IFD)

Figure A. 1: Intensity-Frequency-Duration curves at sub catchment 01, Teviot Brook

Figure A. 2: Intensity-Frequency-Duration curves at sub catchment 159, Upper Logan


Figure A. 3: Intensity-Frequency-Duration curves at sub catchment 445, Albert River

Figure A. 4: Intensity-Frequency-Duration curves at sub catchment 368, Lower Logan


Appendix B – Monte Carlo Results

The design discharge estimates in the Error! Reference source not found. to Error! Reference

source not found. includes an Areal Reduction Factors (ARF) based on total catchment area.

Table B. 1 - URBS model estimated peak design discharges from DEA and TPT approach at The Overflow, Teviot Brook

ARI (years)


DEA TPT

2 164 359

5 340 519

10 525 631

20 742 766

50 969 962

100 1184 1117

200 1380 1307

500 1626 1566

1000 1833 1795

2000 2056 2134

Table B. 2 - URBS model estimated peak design discharges from DEA and TPT approach, Logan River at Round Mountain and Yarrahappini

ARI (years)


Round Mountain Yarrahappini

DEA TPT DEA TPT

2 479 993 538 1428

5 1040 1508 1242 2057

10 1592 1852 2000 2529

20 2197 2226 2879 3170

50 2898 2846 3862 3950

100 3520 3366 4769 4561

200 4124 3902 5579 5248

500 4842 4680 6534 6287

1000 5458 5486 7390 7225

2000 6203 6493 8308 8856


Table B. 3 - 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

2 302 535 355 671

5 622 818 740 980

10 916 1011 1103 1245

20 1232 1234 1493 1503

50 1613 1581 1952 1926

100 1947 1879 2360 2233

200 2445 2203 2960 2641

500 2851 2692 3467 3221

1000 3182 3110 3884 3654

2000 3534 3627 4330 4269


For more information P 1300 GOLDCOAST (1300 465 326) W cityofgoldcoast.com.au

logan river catchment - city of gold coast · logan hydrological model were used for this study...

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