The Shifting Sands of

Noosa

Estuaries & Coasts

Did we manage in the past?

Are we managing now?

Can we manage in the future?1

OUTLINE

Geologic and historic timeline of Noosa

coasts and estuaries

Geo 100 – Understanding coastal and

estuary processes

The past and present of coastal

‘management’ interventions

The future challenges for Noosa coasts

and estuaries2

The Story Line

Apologies to Jules Verne

3

YEARS

Mixing the Metaphor

Captain Nemo Lost Nemo

4

20 000 years Over the Sea

5

The oldest dated evidence of occupation in South East

Queensland comes from Stradbroke Island 20,560 +/-250

BP – Pleistocene, when this area was part of the mainland;

Geologic Sea Level Rise

6

Aboriginal Use of Coast

7

There is evidence of aboriginal

occupation in the Great Sandy Region

for at least the past 5,500 years.

Transformed around 3000 BP with

climate induced changes in rainforest

resources

Demographic and technological

changes occurring approximately 1500

BP may have been triggered by key

areas such as SEQ

Semi-sedentary aboriginal villages and

huge gatherings of several thousand of

people being supported by migratory

fish runs

1871 Map

8

1876 Harbour

Map

9

River mouth

appears to be

closer to First

Point

1920s

10

1920 map

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1930s Sea is Beyond First Point

12

1935 Hastings St

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1938

14

15

1940s ORIGINAL NOOSA SPIT

Large sand bars shifted up

and down the coast with the

channel.

Main Beach, Noosa Woods

and Noosa Spit in the

1940s show a very different

landscape to that of today.

The promontory of the Spit

was less than half its

current size.

Before 1947 Cyclone

16

1947- 48 Cyclone Major Erosion

17

1960s

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60s early 70s

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1971 Map

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1971 at High Tide

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August 1977

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August 1977

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May 1978

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1979

3 metre sea

cliff

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August 1977

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Coastal Observation

Programme (COPE) 1977-80

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COPE Report

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High Seas in 1988

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February 1989 (after pumping)

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GEOGRAPHY 100

31

Sediment Plume-Burdekin River (CSIRO)

Erosion Alexandra Headlands and

Maroochydore (Sunshine Coast Daily)

Estuaries Include deltas, tidal marshes and mangrove swamps

Partially enclosed

Mixing of fresh and salt water

Highly productive

Strongly affected by tides and flows from catchments

MacroalgaeGroundwater

Mangroves

Seagrass

Meadow

Phytoplankton

Terrestrial

VegetationSalt marsh

Estuary conceptual model - http://www.ozcoasts.gov.au

Typical Beach System

33

Processes in the Coastal Zone

© 2012 John Wiley & Sons, Inc.

All rights reserved.

Wind WavesFriction between air and water

and wind pressure transfers

energy to water – form wave

• Fetch-length of water

exposed to the wind

• Wavelength – distance

between wave crests

• Wave trough - depression

between crests

© 2012 John Wiley & Sons, Inc.

All rights reserved.

Waves• Swash – forward surge of wave

• Backwash – return flow of wave

• Undercurrent (undertow) – force of the backwash carries both

material and people

Processes in the Coastal Zone

Coastal Dune Systems

Dunes are part of the active beach system that helps

protect against storm events

Cross-section of a

sandy beach showing

the significant

difference in the

volume of sediment

eroded in high-

magnitude storms

(1:100 year)

compared to seasonal

erosional events.http://www.ozcoasts.gov.au

Beach Profile Dynamics

37

© 2012 John Wiley &

Sons, Inc. All rights

reserved.

Processes in the Coastal Zone

Littoral Drift• Littoral drift = The transport of sediment parallel with the shoreline by the

combined action of beach drift and longshore current transport Longshore drift

Beach drift – waves reach

beach on an angle the

swash pushes sand up the

beach sand - backwash is

perpendicular to beach

carrying material back out

Long shore Drift - zigzag

path that transports

sediment long distances

along the beach

39

Evidence of

Longshore

Drift Kirra

1933 and 1973

after the first

groyne was built

Source:

http://www.tweedsandbypa

ss.nsw.gov.au

40

Tweed Sand Bypass

41

Post Bypass 2004

42

Coastal Morphodynamics

43

44

Dunes and Beach Erosion Clearing and development

on coastal dunes

Coastal engineering –

groynes, retaining walls

interrupt natural sediment

transport

Loss dune vegetation

results in beach erosion

and loss of property

45

© 2012 John Wiley &

Sons, Inc. All rights

reserved.

Processes in the Coastal Zone

Wave Refraction• Headlands - Wave energy concentrated at Headlands where sediment is

eroded

• Wave refraction- Wave fronts slow at headlands and wrap around

headlands

• Pocket beaches – Sediment carried by littoral drift deposits at head of the

bay – crescent shaped beach – long term straightening of the shore

© 2012 John Wiley &

Sons, Inc. All rights

reserved.

Human Interactions with Coastal

Processes

Coastal Engineering• Rip-rap

• Artificial beach nourishment

1960s

48

The First Rock Wall

Following cyclones in 1967–68, panicked

beachfront property owners began dumping

rock in front of their properties to hold back the

sea. With approval from the state

government’s Department of Harbours and

Marine, Noosa Council constructed a boulder

wall that permanently fixed the shape of the

bay. The wall broke up during subsequent

storms, thus requiring further work. 49

Noosa Buffer 40m,

North Shore 150m

50

Straight Sea Wall 1970

51

3. Hays Island becomes Noosa Sound.

52

In 1972, Noosa Council

approved an application to

develop Hays Island as a

canal estate. It was habitat for

inestimable numbers of crabs,

birds and reptiles, and its

mangroves provided essential

shelter for fish fingerlings.

The 144-acre development, called Noosa

Sound, stretched from the bridge behind what

is now the Sheraton Resort all the way to

Munna Point.

The Sound

Sand was pumped from

the river to raise the

land by one metre and

natural channels were

widened to create

artificial waterways.

53

Following the cyclones of 1974 and 1976,

there was panic about the possible

consequences of a cyclonic event combined

with high tide and river surge. At the time some

of Noosa Sound was in direct line of sight to

the open ocean.

1977 study Flood

Discharge

Volume

54

1978 Estimates

Longshore Transport

55

Beach Protection Scheme

1978

56

Works in Progress

57

Before and After Relocation

58

The Spit Extended

In 1977 a scheme for the

“protection” of Hays Island

and “restoration” of Noosa

Beach surfaced, jointly

funded by state and local

governments plus Noosa

Sound’s developers. The

design provided for a

relocation of the river

mouth further northwards

59

The Spit Scheme was

completed in December

1978. Significant erosion

appeared at the southern

end of Noosa Main Beach

only a few months later.

New Groyne in 1988

60

Softer Beach Nourishment

61

1999 Study

62

63

2001

Study

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Wave Conditions

with and without artificial reef

65

Modelled Reef Designs

66

Wave Heights

with different

Reef Designs

67

New Coastal Management

Option in 2001

68

Why wasn’t the Reef Built?

69

Sand Pumping

Trials with a submerged sand-pump began in

December 2004 while plans were developed for

a permanent installation.

70

Pumping Statistics

Approx 1000 cubic metres per day ( 100

truckloads)

Cost $3.50per cu m ( alternate $15-20 cu

m) (Hastings Street Business levey)

Aims to achieve a 1:7 gradient to dissipate

wave energy

On average only need to pump a couple of

times a year , if profile is OK no need to

pump71

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73

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Spit ‘Dog’ Beach Erosion and

Management 2010

75

Doggy Beach Reclaimed

Even though the hydrologists had not modelled their

proposal beyond the Noosa Spit area, council chose to

proceed with the project at an estimated total cost of

$3.6 million. Due to concerns about stream power

some of the planned submerged geotextile bags were

substituted with rocks.

76

Before and After

77

Munna Point Erosion 2012

78

79

80

NOW & INTO FUTURE

81

Ocean acidification

Tracking an Ocean of Carbon FEB 2012 4:02min

Acid Test: The Global Challenge of Ocean Acidification 21:35min

82

OCEAN ACIDIFICATION the name given to the ongoing decrease in the pH and

increase in acidity of the Earth's oceans, caused by the

uptake of anthropogenic carbon dioxide (CO2) from

the atmosphere.

About a quarter of the carbon dioxide in the atmosphere

goes into the oceans, where it forms carbonic acid.

As the amount of carbon has risen in the atmosphere there

has been a corresponding rise of carbon going into the

ocean

Between 1751 and 1994 surface ocean pH is estimated to

have decreased from approximately 8.25 to

8.14, representing an increase of almost 30% in "acidity"

(H+ ion concentration) in the world's oceans.

This ongoing acidification of the oceans poses a threat to the

food chains connected with the oceans. 83

Coral Reefs A rock like accumulation of

carbonates secreted by corals and algae along marine shorelines

Largest variety of species of marine life in a very tiny area

Produce more living biomass than any other marine ecosystem

Remove CO2

Protect against wave action

Very important to fisheries and tourism industries

Problems: very slow growing and easily damaged

Great Barrier Reef

GBRMPA

Mixing the Metaphor

Captain Nemo Lost Nemo

85

Sea Level

Rise

Projections

86

Figure: Estimated

increases in the

frequency of extreme sea

level events (indicated by

the diameters of the

circles), caused by sea

level rises of 10

centimetres (left) and 50

centimetres (right).

1990 - Baseline Summer

Maximum Temperature

2100 – Summer

Maximum Temperature A2

CHANGES TO CONDITIONS IN

SEQ

Most Likely Scenario

More frequent and severe droughts.

Increased intensity of storm events

3-5% decrease in rainfall

Increased flooding and erosion

Increase Nutrient & Temp

driving Algal Blooms?

89

The Story Line

Apologies to Jules Verne

90

YEARS

91