Tweed River Entrance Sand Bypassing Project Letitia Spit to ......TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA MONTHLY ENVIRONMENTAL MONITORING SUMMARY JUNE 2007

Tweed River Entrance Sand Bypassing Project

Letitia Spit to Kirra

Monthly Environmental Monitoring

Summary

JUNE 2007

TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA

MONTHLY ENVIRONMENTAL MONITORING SUMMARY JUNE 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. MEDIA COVERAGE AND COMMUNITY FEEDBACK .......................................................... 10

7. TWEED RIVER LOWER ESTUARY TIDAL CONDITIONS.................................................... 11

8. INDICATIVE LONGSHORE SAND TRANSPORT................................................................. 12

9. ARGUS COASTAL IMAGING SYSTEM................................................................................ 13

10. CONTACT DETAILS ............................................................................................................. 15



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 completed in June.

• The number of vessels that passed through the entrance in June was approximately the same as the average.

• Surf quality in June was moderate, with reports of calm surf conditions across most of 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 less than the June 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 JUNE 2007

PUMPED

Location Snapper Rocks East Duranbah

DREDGED

JUNE 2007

TOTAL DELIVERY

Amount (m3) 60,129 1,956 0 62,085

Total Sand Delivery This Year (January to June 2007)

PUMPED DREDGED

2007 TOTAL

DELIVERY

Amount (m3) 276,793 0 276,793

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

PUMPED DREDGED TOTAL

DELIVERY STAGE 2

Amount (m3) 4,134,634 1,862,793 5,997,427



3

4. TWEED RIVER ENTRANCE CONDITIONS

VOLUNTEER VIDEO MONITORING LOG

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

Date Observations

1 June

Mid Morning

Fine weather. Calm crossing conditions.

15 June

Mid Morning

Overcast. Calm crossing conditions. No breaks in entrance.

22 June

Mid Morning

Fine weather. No breaks in entrance. Waves breaking seaward of the entrance.

29 June

Mid Morning

Fine weather. Fair crossing conditions. Slight swell seaward of the entrance. Maintenance works on southern wall.



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 June 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 Moderate 72

2 Slight 91

3 Moderate 165

4 Moderate 39

5 Moderate 18

6 Moderate 22

7 Moderate 35

8 Moderate 55

9 Slight 25

10 Slight 64

11 Slight 176

12 Slight 87

13 Slight 21

14 Slight 27

15 Slight 22

16 Slight 122

17 Slight 185

18 Moderate 44

19 Moderate 22

20 Slight 23

21 Rough 31

22 Moderate 20

23 Rough 35

24 Moderate 36

25 Rough 7

26 Rough 11

27 Rough 12

28 Rough 10

29 Moderate 48

30 Slight 60



5


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

1

2

3

4

5

01Fri

02Sat

03Sun

04Mon

05Tue

06Wed

07Thu

08Fri

09Sat

10Sun

11Mon

12Tue

13Wed

14Thu

15Fri

16Sat

17Sun

18Mon

19Tue

20Wed

21Thu

22Fri

23Sat

24Sun

25Mon

26Tue

27Wed

28Thu

29Fri

30Sat

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 T

hrough 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

June 2007

0

1

2

3

01Fri

02Sat

03Sun

04Mon

05Tue

06Wed

07Thu

08Fri

09Sat

10Sun

11Mon

12Tue

13Wed

14Thu

15Fri

16Sat

17Sun

18Mon

19Tue

20Wed

21Thu

22Fri

23Sat

24Sun

25Mon

26Tue

27Wed

28Thu

29Fri

30Sat

Date

Sig

nific

ant W

ave

Hei

ght (

m)

0

50

100

150

200

250

300

Daily N

umber of V

essels Passing

Through E

ntrance

Siginficant Wave Height (m) measured at the Tweed Waverider Buoy

75% Wave Height Exceedance for Winter, ~0.9m (1995-2001)



Vessels Passing

Days logged in June: 30 Total Crossings recorded:1,585 Average Crossings per day:53

(NB:Rough sea conditions recorded for)



6


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

August 2006 to June 2007

-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. M

onthly Significant W

ave Height (m

)Monthlynumber ofvesselspassingthrough theentrance

Averagenumber ofvesselspassingthrough theentrance (Ave. 2002-2006)

MonthlyHsig

AveragemonthlyHsig (Ave.2002-2006)



7

5. SURF SUMMARY

Waves of between 0.5 – 1.5 m from the ESE dominated surf conditions on the Southern Gold Coast in June 2007. Winds varied over the month where the most predominant wind conditions were SW and NW at 10-30 Knots.

Readings from the Tweed Waverider Buoy showed a minimum significant wave height of 0.49m on 20 June and a maximum significant wave height of 2.2m on 18 June. There were 19 recorded days when waves dropped below 1.0m and 1 day when waves were above 2.0m.

Surf quality in June was moderate, with reports of calm surf conditions occurring along the month.

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

June 2007Hsig (m.)

0

0.5

1

1.5

2

2.5

3

01Fri

02Sat

03Sun

04Mon

05Tue

06Wed

07Thu

08Fri

09Sat

10Sun

11Mon

12Tue

13Wed

14Thu

15Fri

16Sat

17Sun

18Mon

19Tue

20Wed

21Thu

22Fri

23Sat

24Sun

25Mon

26Tue

27Wed

28Thu

29Fri

30Sat

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 June 2007

30 June – 4 July - Billabong Occy's Grom Comp (Duranbah Beach)

Upcoming events in July 2007

30 June – 4 July - Billabong Occy's Grom Comp (Duranbah Beach)

14-15 July – Billabong Winter Classic (Duranbah Beach)

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



8

SURF SUMMARY CONTINUED

VOLUNTEER SURF QUALITY OBSERVATIONS

The following observations for June 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

1 June

Mid Morning

1.5 – 2m ENE swell, plunging waves. 52 surfers present.

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

1 – 1.5m waves. 1 surfer present. No longshore transport occurring. Offshore bar present. Small scarp at the north from Kirra Point Groyne.

15 June

Mid Morning

1.5 – 2m E swell, plunging waves. 75 surfers present.

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

Flat to <1m spilling waves. 0 surfers present. No longshore transport occurring. Offshore bar present.

22 June

Mid Morning

1 – 1.5m ENE swell. 56 surfers present.

16 surfers present. Average northward longshore transport occurring. No offshore bar apparent.

<1m plunging and spilling waves. 1 surfer present. No longshore transport occurring. Low tide. No breaks on the outer bar. Some recession of the beach line since last observations at Kirra.

29 June

Mid Morning

ENE swell. 43 surfers present.

3 surfers present. Large northward longshore transport occurring.

<1m waves. 3 surfers present. Longshore transport occurring. Offshore bar present. Unpleasant beach conditions.



9

SURF SUMMARY CONTINUED

PHOTOGRAPHS OF SURF CONDITIONS

Duranbah, 27 June 2007 Coolangatta, 27 June 2007

Source: SwellNet

30 June 2007, Billabong Occy’s Grom Comp, Duranbah Beach

Source: Surfing Australia



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6. MEDIA COVERAGE AND COMMUNITY FEEDBACK

MEDIA COVERAGE

20 June 2007, Daily News, “Fingal feels pressure of abuse”

“Ms Williams, a descendant of the Bundjalung people, lives on Letitia Road and says the local environment is at threat because of sandpumping and the continuous onslaught of 4WD owners using the land as their personal playground.”

22 June 2007, Gold Coast Bulletin, “Tide turns Kirra from desert to deep blue sea”

“A high tide of more than 2m on Monday night left the beaches from North Kirra through to Greenmount covered with lagoons.”

25 June 2007, Gold Coast Bulletin, “Big waves barrel in”

“They maybe small but they still like their waves big…The swell peaked at more than 1m at the points from Burleigh Heads through to Snapper Rocks. Pauly Posadas and Olivia Wheeler were among the horde of surfers at Duranbah keen to catch one of the bigger waves.”

30 June 2007, Surfing Australia, “Billabong Occy's Grom Comp”

“A clean 1- 1.5m swell and brisk offshore winds welcomed competitors on day one of the five day event with the blue ribbon 16/U boy’s and girl’s divisions commencing their opening rounds.”



11

7. TWEED RIVER LOWER ESTUARY TIDAL CONDITIONS

The Mean Low Water Spring (MLWS) tide level in the lower Tweed River increased to -0.324 m AHD in June 2007.

The Letitia 2A tidal data for June 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)



12

8. 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 June 2007, 47,000m³ of sand was moved north towards the Tweed River entrance by natural processes. This is less than the modelled average sand transport quantity for the month of June.

LETITIA SPIT INDICATIVE LONGSHORE TRANSPORT ASSESSMENTCumulative Monthly Net Transport

-50,000

-25,000

0

25,000

50,000

75,000

100,000

01 Fri 02Sat

03Sun

04Mon

05Tue

06Wed

07Thu

08 Fri 09Sat

10Sun

11Mon

12Tue

13Wed

14Thu

15 Fri 16Sat

17Sun

18Mon

19Tue

20Wed

21Thu

22 Fri 23Sat

24Sun

25Mon

26Tue

27Wed

28Thu

29 Fri 30Sat

June 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

.)

Net Daily

Avg JuneTrans 1989-1995 (WBMModel)

Avg JuneTrans 1995-2007 (LandsTweedModel)

WaveHeights



13

9. 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 and 4-5 June 2007

30 May 2007

29 June 2007

RAINBOW BAY

30 May 2007

30 June 2007



14

ARGUS COASTAL IMAGING SYSTEM CONTINUED

COOLANGATTA - GREENMOUNT

31 May 2007

30 June 2007

NORTH KIRRA - KIRRA

30 May 2007

30 June 2007



15

10. CONTACT DETAILS

This report was completed by Becky Wong.

For more information regarding the Tweed River Entrance Sand Bypassing Project please refer to the following web addresses:

www.tweedsandbypass.nsw.gov.au

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

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

For all enquires regarding this report, please contact Becky at any of the addresses below:

Becky Wong

Environmental Scientist

Tweed River Entrance Sand Bypassing Project

NSW Department of Lands

[email protected]

Level 12, 10 Valentine Avenue

Parramatta NSW 2124

Ph: (02) 8836 – 5325

Fax: (02) 8836 – 5364

Documents

Tweed River Entrance Sand Bypassing Project Letitia Spit to ......TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA MONTHLY ENVIRONMENTAL MONITORING SUMMARY JUNE 2007