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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
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
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.
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
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
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
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.
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
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
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
5
TWEED RIVER ENTRANCE CONDITIONS CONTINUED
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)
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
6
TWEED RIVER ENTRANCE CONDITIONS CONTINUED
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)
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
7
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
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
8
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.
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
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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
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
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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.”
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
12
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)
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
13
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
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
14
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
TWEED RIVER ENTRANCE SAND BYPASSING PROJECT LETITIA SPIT TO KIRRA
MONTHLY ENVIRONMENTAL MONITORING SUMMARY MAY 2007
15
ARGUS COASTAL IMAGING SYSTEM CONTINUED
COOLANGATTA - GREENMOUNT
24 April 2007
31 May 2007
NORTH KIRRA - KIRRA
30 April 2007
30 May 2007