tresbp environmental monitoring summary may 2009 · tresbp environmental monitoring summary may...

TRESBP ENVIRONMENTAL MONITORING SUMMARY MAY 2009

1

OVERVIEW

In May 2009:

• 50,524 m3 of sand was pumped.

• Three media articles referred directly to the project, one was neutral, two were mainly negative.

• Entrance conditions were good to impassable, with 2,854 boat crossings recorded (roughly 1/3 more than the average amount for the month of May).

• Surf quality was fairly calm and good for most of the month, but extremely dangerous during the high sea event from 19 to 26 May (max Hsig = 5.6m).

• Tweed River tide data for May 2009 has not yet been received. March 2009 river tides conformed to ocean tide patterns and were not significantly impacted by the project.

• Sand transport conditions were fairly calm for most of the month, but increased significantly during the severe storm from 19 to 26 May. The estimated amount of sand moving north towards the Tweed River Entrance by natural processes was about 194,000 m3 (just over three times the May average).

1. SAND PUMPING & DREDGING

Sand Delivery May 2009

Snapper Rocks East: 28,745m3

Duranbah: 21,779m3

Total: 50,524m3

Sand Delivery January to May 2009

Pumped: 248,312m3

Dredged: 0m3

Total: 248,312m3

Sand Delivery January to May 2008

Pumped: 283,644m3

Dredged: 19,791m3

Total: 303,435m3

Stage II Sand Delivery May 2000 to May 2009

Pumped: 5,254,209m3

Dredged: 1,979,755m3

Total: 7,233,964m3

TRESBP ENVIRONMENTAL MONITORING SUMMARY - MAY 2009

2

2. INDICATIVE LONGSHORE TRANSPORT

The graph below is based on a simplified sediment transport model and is indicative only.

May 2009 estimated natural sand transport (moving N towards Tweed entrance): 194,000 m³.

This result is just over three times the average sand transport for the month of May.

LETITIA SPIT INDICATIVE LONGSHORE TRANSPORT ASSESSMENTCumulative Monthly Net Transport

-50,000

-25,000

0

25,000

50,000

75,000

100,000

125,000

150,000

175,000

200,000

01 Fri 02Sat

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15 Fri 16Sat

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22 Fri 23Sat

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29 Fri 30Sat

31Sun

May 2009

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 MayTrans 1995-2007(LitpackModel)

WaveHeights

3. MEDIA COVERAGE

Tweed Daily News, 8 May, “Drama on Tweed bar” “Police said the 43-year old man was an experienced boat operator, but the boat had been swamped by a wave as it crossed the bar”

Tweed Sun, 14 May, “Plans begin to restore surf break” “Major stakeholders in the future of Kirra Beach will meet at the end of the month to start planning to shift sand in a bid to restore the iconic surfing break” Tweed Daily News, 26 May, “Stay out of surf warns lifeguard” “Part of the walkway has washed away at Duranbah and there is lots of debris in the water.” Gold Coast Bulletin, 26 May, “Maligned sand build-up saves Kirra beach from major damage” “’You go anywhere on the Gold Coast now and you’ll see radical erosion, but not at Kirra. I’ve always said that it would take a tsunami to move that sand. We didn’t have a tsunami but it was the next closest thing and the sand is still there,’ said surfer Andrew McKinnon” Tweed Daily News, 28 May, “Storm erosion tipped to last ‘several years’” “Trees started tumbling from the banks to the shore last week. “It’s been going on for years now but it’s even worse after the storms. It has taken so much sand away,” [local resident] Mr Williams said. “Even if they switched the jetty off, it would take years for the beach to return to normal.”


3

4. TWEED RIVER ENTRANCE CONDITIONS

VOLUNTEER MARINE RESCUE MONITORING RESULTS

Weekends and public holidays

Navigation Rating

Impassable-----------Good

Date Entrance Conditions

Impa

ssab

le

Diff

icul

ty

Enc

ount

ered

Som

e D

iffic

ulty

E

ncou

nter

ed

Rel

ativ

ely

Goo

d C

ross

ing

Goo

d C

ondi

tions

Number of Boats

1st Moderate, 20 Kt 47

2nd Moderate, 11 Kt 132

3rd Moderate, 17 Kt 135

4th Moderate, 21 Kt 88








12th Rough, 12 Kt 30



15th Slight, 8 Kt 380




19th Rough, 24 Kt 3

20th Rough, 32 Kt 0

21st Rough, 40 Kt 0

22nd Rough, 40 Kt 4

23rd Rough, 32 Kt 0

24th Rough, 32 Kt 0

25th Rough, 15 Kt 7

26th Rough, 14 Kt 20




30th Moderate 15 Kt 59

31st Moderate, 12 Kt 41

2,854


4

Comparison of the Number of Vessels Passing Through the Entrance per month 2008/9 compared to 2007/08, 2003/4 and 1995 (prior to entrance improvements)

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

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

Mon

thly

No.

Ves

sels

pas

sing

thro

ugh

entra

nce

per m

onth

Number ofvesselspassingthrough theentrance permonth (2008/9)



*Note 2 - Assuming the number of incoming boats = outgoing boats in 94/95Month (2008/9)

2007-08Average crossings per month � 2,300

1995Average crossings per month � 1,000

2003-04Average crossings per month � 1,500

*Note 1 - Based on June to May averages

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

May 2009

0

1

2

3

4

5

6

01Fri

02Sat

03Sun

04Mon

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31Sun

Date

Sig

nific

ant W

ave

Hei

ght (

m)

0

100

200

300

400

500

600

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 May: 31 Total Crossings recorded: 2,854 Average Crossings per day: 19

(NB: Rough sea conditions recorded for 12th, 19th-26th)


5

5. WAVE & SURFING CONDITIONS

Dominant swell condition: Problems with the Tweed Waverider Buoy meant significant amounts of wave data were lost from 4-14, 20, 26 and 31 May so correlations with Brisbane Waverider Buoy were used for analyses. Waves were generally small this month, except during the severe storm that occurred from 19-26 May. Swell direction was mainly from the ENE to ESE, with waves from ENE during the storm event.

High sea events: 19 to 26 May (max Hsig = 5.6 m)

Monthly minimum significant wave height: 0.5 m on 17 May

Monthly maximum significant wave height: 5.6 m on 21 May

Number of days with waves below 1.0 m: 13 days

Number of days with waves above 2.0 m: 8 days (Source: Tweed & Brisbane Waverider Buoys; BoM)

May 2009Hsig (m)

0

1

2

3

4

5

6

01Fri

02Sat

03Sun

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05Tue

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09Sat

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31Sun

Date

Hsi

g (m

)

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

http://www.epa.qld.gov.au/projects/waves/site.cgi?siteid=28&noback=4

UPCOMING SURF & SURF LIFE SAVING EVENTS

• Arnette Queensland Junior Surfing Titles – 6-8 June, Gold Coast

• Fantastic Noodles Regional Junior Surfing Titles – 20 June, Tweed-Byron Coast

• Surfing Far North Coast Surfmasters Titles – 21 June, Tweed-Byron Coast

• Surfing Australia Boys Surf Camp – 29 June to 1 July, Tweed-Byron Coast Source: Surfing Australia & Surf Life Saving Queensland


6

SURF REPORT OVERVIEW

Based on media reports and surf quality observations by volunteer Mr Brian Mason. Date Surfing Conditions

1-18 May Tiny to small SE/ESE surf, variable winds, small fun waves at times.

19-26 May Average ESE surf rising to huge. Stormy conditions and gale force winds at times. Only suitable for experienced tow-in surfers at open beaches. Messy breaks.

27 May Average ESE surf, with light winds. Hazardous debris in water. Clean waves on the points but sand banks have been battered by the storm.

28-31 May Tiny ESE surf, light winds, small fun waves.

6. TIDES

Tweed River April 2009 Mean Low Water Spring (MLWS) tide level: -0.215 m AHD

The TRESBP has not had a significant impact on the Lower Tweed River tidal range to April 2009.

May 2009 tide data has not yet been received.

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-

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Oct

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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 Tweed River(Letitia 2A)


7

Comparison of Spring Tidal Range

Please note that Coffs Harbour gauge was malfunctioning 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

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Apr

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Apr

-09

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)

tresbp environmental monitoring summary may 2009 · tresbp environmental monitoring summary may...

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