The Shifting Sands of Noosa
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The document discusses the historical and ongoing management of Noosa's coastlines and estuaries, highlighting geological changes and human interventions over thousands of years. Key themes include Aboriginal resource use, coastal engineering efforts, and current challenges such as erosion and climate change impacts. It emphasizes the need for sustainable management strategies to address future environmental changes.
The Shifting Sands of Noosa
- 1. The Shifting Sands of Noosa Estuaries & Coasts Did we manage in the past? Are we managing now? Can we manage in the future? 1
- 2. 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 estuaries 2
- 3. The Story Line Apologies to Jules Verne 3 YEARS
- 4. Mixing the Metaphor Captain Nemo Lost Nemo 4
- 5. 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;
- 6. Geologic Sea Level Rise 6
- 7. 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
- 8. 1871 Map 8
- 9. 1876 Harbour Map 9 River mouth appears to be closer to First Point
- 10. 1920s 10
- 11. 1920 map 11
- 12. 1930s Sea is Beyond First Point 12
- 14. 1938 14
- 15. 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.
- 17. 1947- 48 Cyclone Major Erosion 17
- 18. 1960s 18
- 19. 60s early 70s 19
- 20. 1971 Map 20
- 21. 1971 at High Tide 21
- 22. August 1977 22
- 23. August 1977 23
- 24. May 1978 24
- 26. August 1977 26
- 27. Coastal Observation Programme (COPE) 1977-80 27
- 28. COPE Report 28
- 29. High Seas in 1988 29
- 30. February 1989 (after pumping) 30
- 31. GEOGRAPHY 100 31 Sediment Plume-Burdekin River (CSIRO) Erosion Alexandra Headlands and Maroochydore (Sunshine Coast Daily)
- 32. 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 Vegetation Salt marsh Estuary conceptual model - http://www.ozcoasts.gov.au
- 34. Processes in the Coastal Zone © 2012 John Wiley & Sons, Inc. All rights reserved. Wind Waves Friction 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
- 35. © 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
- 36. 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
- 38. © 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. 39 Evidence of Longshore Drift Kirra 1933 and 1973 after the first groyne was built Source: http://www.tweedsandbypa ss.nsw.gov.au
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- 45. 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
- 46. © 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
- 47. © 2012 John Wiley & Sons, Inc. All rights reserved. Human Interactions with Coastal Processes Coastal Engineering • Rip-rap • Artificial beach nourishment
- 48. 1960s 48
- 49. 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
- 50. Noosa Buffer 40m, North Shore 150m 50
- 51. Straight Sea Wall 1970 51
- 52. 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.
- 53. 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.
- 58. Before and After Relocation 58
- 59. 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.
- 60. New Groyne in 1988 60
- 62. 1999 Study 62
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- 64. 2001 Study 64
- 65. Wave Conditions with and without artificial reef 65
- 67. Wave Heights with different Reef Designs 67
- 68. New Coastal Management Option in 2001 68
- 69. Why wasn’t the Reef Built? 69
- 70. Sand Pumping Trials with a submerged sand-pump began in December 2004 while plans were developed for a permanent installation. 70
- 71. 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 pump 71
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- 75. Spit ‘Dog’ Beach Erosion and Management 2010 75
- 76. 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
- 78. Munna Point Erosion 2012 78
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- 81. NOW & INTO FUTURE 81
- 82. Ocean acidification Tracking an Ocean of Carbon FEB 2012 4:02min Acid Test: The Global Challenge of Ocean Acidification 21:35min 82
- 83. 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
- 84. 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
- 85. Mixing the Metaphor Captain Nemo Lost Nemo 85
- 86. 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).
- 87. 1990 - Baseline Summer Maximum Temperature 2100 – Summer Maximum Temperature A2
- 88. 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
- 89. Increase Nutrient & Temp driving Algal Blooms? 89
- 90. The Story Line Apologies to Jules Verne 90 YEARS
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