AU-EEZ
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The Australian Geological Survey Organistaion, in co-operation with Desmond Fitzgerald and Associates and the Australian Hydrographic Service, has produced a set of digital bathymetry, gravity and magnetic grids for Australia's margin, with resolutions of 250-1000m. They represent a major upgrade of marine ship-track potential field and bathymetry data in Australian waters for the purpose of developing fundamental products for geological interpretation. In integrating data from many sources, levelling techniques have been developed to correct crossover and other errors, and the ship-track data have been merged with satellite and high-resolution onshore sources.
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The benthic (sea floor) component of the National Marine Bioregionalisation covers the 80% of Australia's Exclusive Economic Zone that lies beyond the continental shelf break. It provides a description of patterns of biological distributions and physical habitats on the seafloor. The Benthic Bioregionalisation Report is a technical document describing how the benthic bioregions were created. It includes descriptions of all the datasets used, details of each bioregion, and examples of how the physical data may be used to sub-divide the marine bioregions for management. An evaluation of the benthic bioregionalisation including strengths, weaknesses and future work is also contained in the report.
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For the first time, the distribution of seafloor geomorphic features has been systematically mapped over much of the Australian margin and adjacent seafloor. Each of 21 feature types was identified using a new, 250 m spatial resolution bathymetry model and supporting literature. The total area mapped was 48.9 million km2 and included the seafloor surrounding the Australian mainland and island territories of Christmas, Cocos (Keeling), Macquarie and Norfolk Islands. Of this total mapped area, the shelf is 41.9 million km2 (21.92%), the slope 44.0 million km2 (44.80%) and the abyssal plain/deep ocean floor 42.8 million km2 (32.20%). The rise covers 97 070 km2 or 1.08% of the mapped area. A total of 6702 individual geomorphic features were mapped. Plateaus have the largest surface area and cover 1.49 million km2 or 16.54%, followed by basins (714 000 km2; 7.98%), and terraces (577 700 km2; 6.44%), with the remaining 14 types each making up 55%. Reefs, which total 4172 individual features (47 900 km2; 0.54%), are the most numerous type of geomorphic feature, principally due to the large number of individual coral reefs of the Great Barrier Reef. The geomorphology of the margin is most complex where marginal plateaus, terraces, trench/troughs and submarine canyons are present. Comparison with global seafloor geomorphology indicates that the Australian margin is relatively under-represented in shelf and rise and over-represented in slope area, a pattern that reflects the mainland being bounded on three sides by rifted continent ocean margins and associated large marginal plateaus. Significantly, marginal plateaus on the Australian margin cover 20% of the total world area of marginal plateaus. The mapped area can be divided into 10 geomorphic regions by quantifying regional differences in diagnostic assemblages of features, and these regions can be used as a starting-point to infer broad-scale seafloor habitat types.
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An important aim of the comparative geomorphology of estuaries project was to increase understanding of the environmental characteristics of near-pristine estuaries and provide a reference dataset for quantifying changes in habitat patterns in modified systems. It was anticipated that this aim would be fulfilled by identifying key geomorphic characteristics of the near-pristine systems that may be used to benchmark the current condition of, and quantify change within, 'modified' waterways. Here we provide examples of some very promising results obtained from our preliminary analyses of the geomorphic habitat area information contained within the GIS maps available on OzEstuaries.
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Hydrogeological map data for research and analysis applications, most commonly in GIS systems. Georeferenced, attributed, GIS vector format data of hydrogeological map information at all scales.
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Selected geomorphic features and sedimentary facies were mapped in 283 of Australia's wave- and tide-dominated estuaries and deltas to quantitatively evaluate established evolutionary facies models that depict the evolution of estuaries into deltas during stable sea level conditions. While diagnostic facies for wave- and tide-dominated estuaries and deltas approximate those specified by the models, statistical analyses of the data also reveal two additional insights regarding the evolution of estuaries to deltas. First, there is an offshore shift in the locus of sand accumulation between tide-dominated estuaries and deltas, associated with the onset of delta development. Second, the mean surface area of intertidal environments (i.e., intertidal flats, mangroves/melaleuca, saltmarsh/salt flat facies) is greater in wave-dominated deltas than in wave-dominated estuaries. Tidal penetration associated with the river establishing a more direct and permanent connection to the sea during late-stage development presents a natural impediment to continued formation of an alluvial plain and full development of the 'classic' wave-dominated delta morphology. A notional evolutionary pathway for wave-dominated estuaries is developed from the distribution of facies that predicts the rate and susceptibility of geomorphic and habitat changes. The 'classic' deltaic geomorphology may be unattainable for wave-dominated systems, except those with significant terrigenous sediment inputs. Our study is the first published example of geomorphic and sedimentary data assembled from a large number of wave- and tide-dominated estuaries and deltas across an entire continent.
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This report describes the iterative methods used to create the seascapes, including a detailed appendix documenting the different datasets used in the different planning zones. Creating the seascapes is necessarily an iterative process whereby the available datasets are combined in different combinations, or added as they become available, using an unsupervised 'crisp' ISOClass classification in ERMapper. In each classification only biophysical properties that have consistent and definable relationships with the benthic biota and are known in sufficient detail across Australia's entire marine region are used to create the seascapes. An initial validation of the classification technique has been undertaken on a subset of the data for the shelf surrounding Tasmania using an alternative unsupervised 'fuzzy' classification. Results of this validation indicate that the unsupervised classification methodology provides consistent and reliable classes for defining the seascapes.
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In order to design a representative network of high seas marine protected areas (MPAs), an acceptable scheme is required to classify the benthic bioregions of the oceans. Given the lack of sufficient biological information to accomplish this task, we used a multivariate statistical method with 6 biophysical variables (depth, seabed slope, sediment thickness, primary production, bottom water dissolved oxygen and bottom temperature) to objectively classify the ocean floor into 11 different categories, comprised of 53,713 separate polygons, that we have termed "seascapes". Validation of the seascape classification was carried out by comparing the seascapes with an existing map of seafloor geomorphology, and by GIS analysis of the number of separate polygons and perimeter/area ratio. We conclude that seascapes, derived using a multivariate statistical approach, are biophysically meaningful subdivisions of the ocean floor and can be expected to contain different biological associations, in as much as different geomorphological units do the same. Our study illustrates how the identification of potential sites for high seas marine protected areas can be accomplished by GIS analysis of seafloor geomorphic and seascape classification maps. Using this approach, maps of seascape and geomorphic heterogeneity were generated in which heterogeneity hot-spots identify themselves as MPA candidates. The use of computer-aided mapping tools removes subjectivity in the MPA design process and provides greater confidence to stakeholders that an unbiased result has been achieved.
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Geoscience Australia and the National Oceans Office carried out a joint project to produce a consistent, high-quality 9 arc second (0.0025° or ~250m at the equator) bathymetric data grid of those parts of the Australian water column jurisdiction lying between 92º E and 172º E and 8 º S and 60º S. As well as the waters adjacent the continent of Australia and Tasmania, the area selected also covers the area of water column jurisdiction surrounding Macquarie Island, and the Australian Territories of Norfolk Island, Christmas Island, and Cocos (Keeling) Islands. The area selected does not include Australia's marine jurisdiction off the Territory of Heard and McDonald Islands and the Australian Antarctic Territory.
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The collection supports the compilation of national mineral resource and production statistics, and mineral prospectivity analysis. The collection includes the OZMIN database (Australian mineral deposit descriptions including geological, resource and production data); the MINLOC database (mineral occurrence locations sourced from Geoscience Australia and state and territory geological surveys); supporting GIS datasets (eg,mineral prospectivity datasets, ports, power stations); maps and reports.