Tweed River Entrance Sand Bypassing Project Letitia Spit to Kirra€¦ · Surf quality in May was...

Tweed River Entrance Sand Bypassing Project

Letitia Spit to Kirra

Monthly Environmental Monitoring

Summary

MAY 2007

TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA

MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007

TABLE OF CONTENTS

1. EXECUTIVE SUMMARY ........................................................................................................... 1

2. INTRODUCTION ....................................................................................................................... 2

3. PUMPING AND DREDGING ACTIVITIES ................................................................................ 2

4. TWEED RIVER ENTRANCE CONDITIONS.............................................................................. 3

5. SURF SUMMARY...................................................................................................................... 7

6. BEACH CONDITIONS............................................................................................................. 10

7. MEDIA COVERAGE AND COMMUNITY FEEDBACK........................................................... 11

8. TWEED RIVER LOWER ESTUARY TIDAL CONDITIONS .................................................... 12

9. INDICATIVE LONGSHORE SAND TRANSPORT.................................................................. 13

10. ARGUS COASTAL IMAGING SYSTEM ................................................................................. 14



1

1. EXECUTIVE SUMMARY

This report provides a summary of pumping and dredging activities, as well as surf, beach, river, entrance and weather conditions for the southern Gold Coast Beaches, Duranbah, the Tweed River Entrance and Letitia Spit.

• Pumping to Duranbah was carried out from 2-28 May 2007.

• The number of vessels that passed through the entrance in May was significantly higher than on average.

• Surf quality in May was generally good, with reports of excellent surf conditions occurring in the middle the month..

• There were no significant impacts on the Lower Tweed River tides. Recent tidal data is consistent with ocean tidal levels.

• The amount of sand moving north towards the Tweed River entrance was approximately half the May average.



2

2. INTRODUCTION

This document provides a summary of sand quantities delivered by the system, as well as surf, beach, river, entrance and weather conditions for the southern Gold Coast Beaches, Duranbah, the Tweed River Entrance and Letitia Spit for ongoing monitoring purposes.

Information has been sourced from TRESBP monitoring programs, GCCC coastal reports, media coverage, Surfing NSW and Surfing Queensland and the following World Wide Websites:

• www.burleighcam.com.au

• www.coastalwatch.com.au

• www.swellnet.com.au

• www.bom.gov.au

• www.surfingaustralia.com.au

• www.tracksmag.com

3. PUMPING AND DREDGING ACTIVITIES

Sand Delivery for MAY 2007

PUMPED

Location Snapper Rocks East Duranbah

DREDGED MAY 2007

TOTAL DELIVERY

Amount (m3) 19,496 19,766 0 39,262

Total Sand Delivery This Year (January to May 2007)

PUMPED DREDGED

2007 TOTAL

DELIVERY

Amount (m3) 214,708 0 214,708

Total Sand Delivery to Date by the Stage 2 Permanent Sand Bypassing System (May 2000 to May 2007)

PUMPED DREDGED TOTAL

DELIVERY STAGE 2

Amount (m3) 4,072,549 1,862,793 5,935,342

http://www.burleighcam.com.au/

http://www.coastalwatch.com.au/

http://www.swellnet.com.au/

http://www.bom.gov.au/

http://www.surfingaustralia.com.au/

http://www.tracksmag.com/



3

PUMPING AND DREDGING ACTIVITIES CONTINUED

PHOTOGRAPHS OF DURANBAH PUMPING

Pumping and nourishment works at Duranbah were carried out from 2-28 May 2007.

Pumping to Duranbah, 9 May 2007

Duranbah Dozer works, 10 May 2007

4. TWEED RIVER ENTRANCE CONDITIONS

VOLUNTEER VIDEO MONITORING LOG

The following Entrance Condition observations for May 2007 were recorded by volunteers Mr Brian Mason and Mr Robert Ford:

Date Observations

4 May Mid Morning

Fine weather. Good crossing conditions. Vessels entering.

11 May Mid Morning

Cloudy. Poor crossing conditions. Waves breaking. Dangerous conditions for small craft.

25 May Mid Morning

Cloudy. Good crossing conditions. Small boats entering.



4

TWEED RIVER ENTRANCE CONDITIONS CONTINUED

VOLUNTEER MARINE RESCUE REPORTS

Volunteer Marine Rescue Pt Danger (VMR) has been monitoring daily entrance conditions on behalf of the TRESBP since 20 January 2002, monitoring results for May 2007 are presented below.

The navigation ratings from 1–5 are as follows: 1 – Impassable 2 – Difficulty encountered 3 – Some difficulty encountered 4 – Relatively good crossing 5 – Good conditions

– Weekends and public holidays

Navigation Rating Impassable-----------Good Date Entrance Conditions

1 2 3 4 5

Number of Boats

1 Slight 92 2 Slight 65 3 Moderate 76 4 Moderate 82 5 Moderate 141 6 Moderate 273 7 Slight 261 8 Moderate 54 9 Moderate 40 10 Moderate 67 11 Rough 18 12 Rough 31 13 Rough 0 14 Rough 36 15 Rough 37 16 Moderate 100 17 Moderate 162 18 Moderate 81 19 Moderate 131 20 Slight 215 21 Slight 120 22 Slight 70 23 Slight 64 24 Slight 75 25 Slight 134 26 Moderate 94 27 Slight 77 28 Slight 41 29 Moderate 27 30 Slight 33 31 Moderate 47



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Daily Number of Vessels Passing Through Tweed River Entrance and Navigation Conditions, May 2007

1

2

3

4

5

01Tue

02Wed

03Thu

04Fri

05Sat

06Sun

07Mon

08Tue

09Wed

10Thu

11Fri

12Sat

13Sun

14Mon

15Tue

16Wed

17Thu

18Fri

19Sat

20Sun

21Mon

22Tue

23Wed

24Thu

25Fri

26Sat

27Sun

28Mon

29Tue

30Wed

31Thu

Date

Rat

ing

from

1 to

5 (1

bei

ng im

pass

able

, 5

bein

g go

od n

avig

atio

nal c

ondi

tions

)

0

50

100

150

200

250

300

Daily N

umber of V

essels Passing Through E

ntrance

Navigation rating

Boats Passing

NB. 1. Peaks in number of vessels passing frequently coincide with weekends.2. Forecast conditions may influence number of vessels passing.

Daily Number of Vessels Passing through Tweed River Entrance and Significant Wave Heights

May 2007

0

1

2

3

01Tue

02Wed

03Thu

04Fri

05Sat

06Sun

07Mon

08Tue

09Wed

10Thu

11Fri

12Sat

13Sun

14Mon

15Tue

16Wed

17Thu

18Fri

19Sat

20Sun

21Mon

22Tue

23Wed

24Thu

25Fri

26Sat

27Sun

28Mon

29Tue

30Wed

31Thu

Date

Sign

ifica

nt W

ave

Hei

ght (

m)

0

50

100

150

200

250

300

Daily N

umber of Vessels P

assing Through E

ntrance

Siginficant Wave Height (m) measured at the Tweed Waverider Buoy75% Wave Height Exceedance for Winter, ~0.9m (1995-2001)50% Wave Height Exceedance for Winter, ~1.2m (1995-2001)25% Wave Height Exceedance for Winter, ~1.5m (1995-2001)Vessels Passing

Days logged in May: 31Total Crossings recorded:2744Average Crossings per day:89

(NB:No rough sea conditions recorded 11-15/5)



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Comparison of the Average and Monthly Number of Vessels Passing Through the Entrance and the Average and Monthly Significant Wave Heights

August 2006 to May 2007

Monthlynumber ofvesselspassingthrough theentrance

-2,000

-1,500

-1,000

-500

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

August September October November December January February March April May June July

2006 2007

Mon

thly

No.

Ves

sels

pas

sing

thru

ent

ranc

e

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

Ave. Monthly Significant W

ave Height (m

)

Averagenumber ofvesselspassingthrough theentrance (Ave. 2002-2006)

MonthlyHsig

AveragemonthlyHsig (Ave.2002-2006)



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5. SURF SUMMARY

Waves of between 0.5 – 1.5 m from the E dominated surf conditions on the Southern Gold Coast in May 2007. Winds varied over the month where the most predominant wind conditions were SE and NW at 10-25 Knots.

Readings from the Tweed Waverider Buoy showed a minimum significant wave height of 0.37m on 1 May and a maximum significant wave height of 2.41m on 12 May. There were 21 recorded days when waves dropped below 1.0m and 3 days when waves were above 2.0m.

Surf quality in May was generally good, with reports of excellent surf conditions occurring in the middle the month.

Source: Tweed and Brisbane Waverider Buoy, RealSurf, Swellnet, Burleighcam, Coastalwatch, BoM.

May 2007Hsig (m.)

0

0.5

1

1.5

2

2.5

3

30Mon

01Tue

02Wed

03Thu

04Fri

05Sat

06Sun

07Mon

08Tue

09Wed

10Thu

11Fri

12Sat

13Sun

14Mon

15Tue

16Wed

17Thu

18Fri

19Sat

20Sun

21Mon

22Tue

23Wed

24Thu

25Fri

26Sat

27Sun

28Mon

29Tue

30Wed

31Thu

Date

Hsi

g (m

.)

A link to data recorded continuously at the Tweed Waverider Buoy is available at:

www.epa.qld.gov.au/sandbypass/

SURF & SURF LIFE SAVING EVENTS

Events in May 2007

9-13 May - Malfunction Longoard (Rainbow Bay/Coolangatta)

Upcoming events in June 2007

3 June - Printpoint Masters Surfing Circuit

9-11 June - Quiksilver Queensland Junior Series

30 June – 4 July - Billabong Occy's Grom Comp

Source: Surfing Australia, Surf Life Saving Australia & Surf Life Saving Queensland

http://www.env.qld.gov.au/sandbypass/



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SURF SUMMARY CONTINUED

VOLUNTEER SURF QUALITY OBSERVATIONS

The following observations for May 2007 were made by volunteers Mr Brian Mason and Mr Robert Ford on behalf of the TRESBP.

Date Duranbah Frog’s Beach / Snapper Rocks Kirra Point

4 May Mid Morning

1 – 1.5m NE swell, spilling waves. 13 surfers present. Flat surfing conditions.

0 surfers present. No longshore transport occurring. No offshore bar apparent.

Flat to <1m spilling waves. 0 surfers present. No longshore transport occurring. Unpleasant conditions.

11 May Mid Morning

1.5 – 2m ENE swell, plunging waves. 20 surfers present.

76 surfers present. Large longshore transport occurring. No offshore bar apparent.

1 – 1.5m spilling waves. 1 surfer present. No longshore transport occurring. Offshore bar present.

25 May Mid Morning

1 – 1.5m ENE swell. 32 surfers present.

14 surfers present. No longshore transport occurring.

<1m spilling waves. 2 surfers present. No longshore transport occurring. Offshore bar present.



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6. BEACH CONDITIONS

PHOTOGRAPHS OF BEACH CONDITIONS

DURANBAH RAINBOW BAY

9 May 2007

View from Greenmount, 10 May 2007

COOLANGATTA

View from Greenmount , 9 May 2007

View from Kirra, 9 May 2007

KIRRA

9 May 2007

9 May 2007

Source: Department of Lands



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7. MEDIA COVERAGE AND COMMUNITY FEEDBACK

MEDIA COVERAGE

13 May 2007, Surfing Australia, “Malfunction”

“Day 4 of the 2007 Malfunction Surf festival scored excellent surf at Rainbow Bay again on the famous “Superbank” with spitting barrels and waves lining up from Snapper Rocks to Coolangatta.”

16 May 2007, Gold Coast Bulletin, “Pumping at D’bah”

“Sand pumping is back at Duranbah Beach with the blessing of Kirra Surfriders Club boss Darryl Green.”

31 May 2007, Daily News, “Rage prompts waves rules guide”

“The 40-year old Lennox Had local has competed in some of the world’s most prestigious competitions but admits she has also been the victim of the seedier side of the increasingly popular sport, surf rage…At Snapper Rocks yesterday Mrs Watts said it was time to regulate surfing.”



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8. TWEED RIVER LOWER ESTUARY TIDAL CONDITIONS

The Mean Low Water Spring (MLWS) tide level in the lower Tweed River decreased to -0.402 m AHD in May 2007.

The Letitia 2A tidal data for February mirrored the Mooloolaba tidal trends indicating that the TRESBP has not had a significant impact on Lower Tweed River tidal range to date.

Changes in the Monthly Mean Low Water Spring Tide Level in the Lower Tweed River

compared with Ocean LevelsPlease note that Coffs Harbour gauge was misfunctioning over

the period from May 2001 to March 2002

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

Jan-00

Apr-00

Jul-00

Oct-00

Jan-01

Apr-01

Jul-01

Oct-01

Jan-02

Apr-02

Jul-02

Oct-02

Jan-03

Apr-03

Jul-03

Oct-03

Jan-04

Apr-04

Jul-04

Oct-04

Jan-05

Apr-05

Jul-05

Oct-05

Jan-06

Apr-06

Jul-06

Oct-06

Jan-07

Apr-07

Date

Ele

vatio

n (m

AH

D)

Tweed River (Letitia 2A) low tide level

Coffs Harbour ocean tide level

Mooloolaba ocean tide level

Lower limit of expected changes in the low tide level in the TweedRiver (Letitia 2A)

Comparison of Spring Tidal Range

Please note that Coffs Harbour gauge was misfunctioning over the period from May 2001 to March 2002

0.5

0.6

0.7

0.8

0.9

1

Jan-00

Apr-00

Jul-00

Oct-00

Jan-01

Apr-01

Jul-01

Oct-01

Jan-02

Apr-02

Jul-02

Oct-02

Jan-03

Apr-03

Jul-03

Oct-03

Jan-04

Apr-04

Jul-04

Oct-04

Jan-05

Apr-05

Jul-05

Oct-05

Jan-06

Apr-06

Jul-06

Oct-06

Jan-07

Apr-07

Month

Rat

io

Letitia - Coffs Harbour Ratio

Letitia - Mooloolaba Ratio

EIS/IAS Existing Condition (Pre-Stage 2, 0.67)

200,00m3 Flood Scour Projected Condition (0.84)

Expected Change Due to Entrance Deepening (0.71)



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9. INDICATIVE LONGSHORE SAND TRANSPORT

The longshore sand transport information presented in the graph below is based on a simplified sediment transport model and should only be used as an indicator of the actual sand transport quantities for the month.

It is estimated that during May 2007, 31,000m³ of sand was moved north towards the Tweed River entrance by natural processes. This is approximately half the modelled average sand transport quantity for the month of May.

LETITIA SPIT INDICATIVE LONGSHORE TRANSPORT ASSESSMENTCumulative Monthly Net and Gross Transport

-50,000

-25,000

0

25,000

50,000

75,000

100,000

125,000

150,000

175,000

30Mon

01Tue

02Wed

03Thu

04Fri

05Sat

06Sun

07Mon

08Tue

09Wed

10Thu

11Fri

12Sat

13Sun

14Mon

15Tue

16Wed

17Thu

18Fri

19Sat

20Sun

21Mon

22Tue

23Wed

24Thu

25Fri

26Sat

27Sun

28Mon

29Tue

30Wed

31Thu

May 2007

Sedi

men

t Tra

nspo

rt (c

u m

), no

rthw

ard

posi

tive

0

5

10

15

20

Wav

e H

eigh

ts (m

.)

Gross Daily

Net Daily

Avg MayTrans(WBMModel)

Avg MayTrans(DLWCTweedModel)

WaveHeights



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10. ARGUS COASTAL IMAGING SYSTEM

The University of New South Wales is monitoring Letitia Spit to North Kirra for the project using an ARGUS coastal imaging system. Images are available on the internet at the following address:

http://www.wrl.unsw.edu.au/coastalimaging/public/tweed/index.html

These images are updated hourly and all past photos can be accessed in the archives.

Merged and rectified images taken at mid tide for each of the locations are shown below. Refer to Appendix A for beach width and shoreline analysis for each of the beaches.

DURANBAH BEACH Note: Sand was pumped to Duranbah beach from 2-28 May 2007

30 April 2007

30 May 2007

RAINBOW BAY

30 April 2007 30 May 2007

http://www.wrl.unsw.edu.au/coastalimaging/public/tweed/index.html



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ARGUS COASTAL IMAGING SYSTEM CONTINUED

COOLANGATTA - GREENMOUNT

24 April 2007

31 May 2007

NORTH KIRRA - KIRRA

30 April 2007

30 May 2007

ncrawford

Text Box

APPENDIX A - BEACH WIDTHS

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