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  • The south-west coast of Western Australia is made up of a series of exposed limestone headlands which are prone to the development of cliff lines and large overhangs. Coastal processes such as wind and water erosion in conjunction with salt crystallisation and carbonate dissolution make these cliffs highly susceptible to collapse. The damaging impact that these unstable cliffs can have on the community was demonstrated on 27 September 1996, when four adults and five children were killed in a rockfall at Huzzas Beach, Gracetown.

  • Fresh groundwater stored in Australian coastal aquifers constitutes an important resource for humans and the natural environment. However, many Australian coastal aquifers are vulnerable to seawater intrusion the landward encroachment of seawater into coastal aquifers. This report is one technical assessment of the National Seawater Intrusion Project, aimed at characterising current and future seawater intrusion vulnerability of Australian coastal aquifers. This report outlines the development of a typological framework to categorise coastal aquifers and assist in their assessment of vulnerability. The report includes a characterisation of the different hydrogeological and climatic settings of Australia's coastal aquifer. Using public and confidential information, simplified cross-sectional conceptual models of case study areas were developed and aquifer parameters were tabulated for 28 case study areas (CSAs). Key hydrogeological characteristics are analysed and tabulated for use in other aspects of the overall vulnerability assessment.

  • There is a growing need for a nationally consistent geomorphology map of the Australian coastal zone. This map, presented in detailed polygon format, will identify the location and extent of geomorphological units that are particularly susceptible to the impacts of sea level rise. For much of the Australian coast this map is already achievable by amalgamating and reclassifying existing datasets into a nationally consistent coastal geomorphology scheme. Vast stretches of the Australian coast however are only mapped at coarse resolutions (i.e. 1:500K - 1:1M small scale) and as such do not allow for a detailed classification. The following paper provides a summary of existing digital polygon datasets and identifies coastal areas where data coverage is particularly poor. Future coastal mapping work should focus on these priority areas. By filling gaps in data coverage a more comprehensive analysis of coastal vulnerability to the impacts of climate change is achievable.

  • Beach ridges at Keppel Bay, central Queensland, Australia, preserve a record of sediment accumulation from the historical period back to middle Holocene times. The ridges comprise fine, well-sorted, feldspar-rich quartz sand that was eroded from the Fitzroy River catchment, deposited in Keppel Bay during floods of the Fitzroy River, and reworked onshore into beach and foredune deposits by the prevailing currents, waves and wind. These floods have an average recurrence interval of at least 7 yr and are induced by the passage of cyclones onshore into the large Fitzroy catchment. The youngest series of beach ridges sit sub-parallel to the modern beach and comprise six accretional units, each unit formed by a set of ridges and delineated by prominent swales. Optically stimulated luminescence (OSL) ages of beach ridges in these units indicate they were deposited in periods of rapid progradation approximately 1500, 1000, 450 and 230 yr BP, when there was an enhanced supply of sediment to the beach from the Fitzroy River via Keppel Bay. Estimates of the mass of sediment stored in the beach-ridge strandplain show that it represents a significant sediment store, potentially trapping the equivalent of 79% of the estimated long-term (100 yr) average annual bedload of the Fitzroy River that is deposited in Keppel Bay. There has been a reduction in the rate of sediment accumulation in the strandplain since around 1000 yr BP, which is consistent with other coastal records in eastern Australia of a relatively wetter phase of climate in the late Holocene compared to the present. The youngest beach ridges (OSL ages < 100 yr BP) are tall relict foredunes that reflect a low rate of sediment accumulation. These ridges have a distinctive trace-element composition produced by a greater contribution from catchment areas with basaltic soils. The change in catchment provenance has likely been a consequence of erosion that followed clearing of native vegetation in these areas. Our findings demonstrate the important insights that beach-ridge deposits proximal to a river sediment source can provide into processes of sediment accumulation and the response to variations in climate in tropical coastal sedimentary systems.

  • Recent centuries provide no precedent for the 2004 Indian Ocean tsunami, either on the coasts it devastated or within its source area. The tsunami claimed nearly all of its victims on shores that had gone 200 years or more without a tsunami disaster. The associated earthquake of magnitude 9.2 defied a Sumatra-Andaman catalogue that contains no nineteenth-century or twentieth-century earthquake larger than magnitude 7.9. The tsunami and the earthquake together resulted from a fault rupture 1,500 km long that expended centuries -worth of plate convergence. Here, using sedimentary evidence for tsunamis, we identify probable precedents for the 2004 tsunami at a grassy beach-ridge plain 125 km north of Phuket. The 2004 tsunami, running 2 km across this plain, coated the ridges and intervening swales with a sheet of sand commonly 5-20 cm thick. The peaty soils of two marshy swales preserve the remains of several earlier sand sheets less than 2,800 years old. If responsible for the youngest of these pre-2004 sand sheets, the most recent full-size predecessor to the 2004 tsunami occurred about 550-700 years ago.

  • Geoscience Australia carried out marine surveys in Jervis Bay (NSW) in 2007, 2008 and 2009 (GA303, GA305, GA309, GA312) to map seabed bathymetry and characterise benthic environments through co-located sampling of surface sediments (for textural and biogeochemical analysis) and infauna, observation of benthic habitats using underwater towed video and stills photography, and measurement of ocean tides and wave-generated currents. Data and samples were acquired using the Defence Science & Technology Organisation (DSTO) Research Vessel Kimbla. Bathymetric mapping, sampling and tide/wave measurement were concentrated in a 3x5 km survey grid (named Darling Road Grid, DRG) within the southern part of the Jervis Bay, incorporating the bay entrance. Additional sampling and stills photography plus bathymetric mapping along transits was undertaken at representative habitat types outside the DRG. This 128 sample data set comprises major, minor and trace elements derived from x-ray fluorescence analysis of surface seabed sediments (~0-2 cm). Sediment surface area data are also presented. More Information: Radke, L.C., Huang, Z., Przeslawski, R., Webster, I.T., McArthur, M.A., Anderson, T.J., P.J. Siwabessy, Brooke, B. 2011. Including biogeochemical factors and a temporal component in benthic habitat maps: influences on infaunal diversity in a temperate embayment. Marine and Freshwater Research 62 (12): 1432 - 1448. Huang, Z., McArthur, M., Radke, L., Anderson, T., Nichol, S., Siwabessy, J. and Brooke, B. 2012. Developing physical surrogates for benthic biodiversity using co-located samples and regression tree models: a conceptual synthesis for a sandy temperature embayment. International Journal of Geographical Information Science DOI:10.1080/13658816.2012.658808.

  • Map for ITR tourist ministerial brief showing leases, coastal waters, and reefs in Ningaloo area. Not for public distribution.

  • A digital relief model (DRM) of the Swan Coastal Plain and Rottnest Shelf (7400 km2) was built with a range of topographic and high-resolution bathymetric datasets, gridded to a 50 m cell size. The DRM enabled the delineation of relict coastal landforms, benthic habitats and development of a regional morphostratigraphic framework. Well-defined features include: 1. Limestone ridges on the coastal plain that sit subparallel to the modern shoreline - these are coastal barriers deposited during Quaternary interglacial periods of high sea level; 2. Rocky reefs on the inner shelf that rise up to 10 m above the adjacent seafloor, remnants of coastal dune barriers that formed when sea level was 20 to 30 m lower than present, and; 3. A discontinuous ridge 3 to 10 m thick along the outer shelf - a relict coastal barrier that formed when sea level was around 60 m lower than present. The DRM provides a useful regional perspective of the distribution and form of these extensive reefs.

  • This study examined the geomorphology of the sea bed, the spatial distribution of the various sediment types and the geomorphic evolution of Cockburn Sound.

  • Coastal lagoons are a type of estuary, which has highly variable assemblages of primary producer groups. A classification is derived distinguishing microphytobenthos-dominated, perennial and ephemeral submerged aquatic vegetation-dominated, and nutrient- and light-limited phytoplankton-dominated lagoons. The principle variables required for the classification are bathymetry, light attenuation and initial solar radiation, dissolved inorganic nitrogen concentration and the area covered by ephemeral and perennial submerged aquatic vegetation. Biogeochemical processes and system-wide nutrient dynamics are inherently coupled to the distribution of primary producer groups, so that the classification provides inferences on water quality and ecosystem functioning for different lagoon types and supports the development of management plans and ecological status assessments. Four case studies representing different lagoon types from the temperate south-eastern and south-western coast of Australia are presented. It is demonstrated that the distribution of primary producer groups, and consequently the lagoon type, can be temporarily variable, e.g. as a function of seasonal solar radiation and light attenuation, the water level in a closed lagoon or the degree of eutrophication.