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Geomorphology and Regolith and Landscape Evolution

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    The MOU74 Box, off the northwest Australian coastline, is an area of approximately 50,000 sq. km within the Australian Fishing Zone. It contains five large, shallow reef systems (less than 15 m deep) ranging in size from 227 sq. km (Ashmore Reef) to 4.5 sq. km (Browse Island). They total approximately 560 sq. km in area. Immediately north of the MOU74 Box within the Australian Fishing Zone (Little Area A) is another shallow reef, Hibernia Reef. In addition to the shallow reefs, there is approximately 925 sq. km of shoal areas (15 to 50 m deep) within the MOU74 Box and 301 sq. km of shoal areas in Little Area A. The reefs and shoals support populations of sedentary reef resources including several species of holothurians (beche-de-mer, sea cucumbers) and trochus, as well as reef-associated fin-fish and sharks. These resources have been fished for many years by Indonesian fishers. Ashmore Reef was declared a Marine Nature Reserve in 1983, banning the removal of fauna and flora to a depth of 50 m. The remaining reefs in the area are under continued, and probably increasing, fishing pressure. The marine resources of the MOU74 Box are managed by the Australian Government. Under the terms of a memorandum of understanding (MOU) between the Australian and Indonesian governments, continued traditional fishing by Indonesian fishing vessels is allowed, principally for sedentary resources such as beche-de-mer (trepang) and trochus, but also fin-fish and reef shark. Apart from limited catch data collected by surveillance and regulatory authorities, little is known about the catch of the Indonesian fishers and the effects of fishing on the target species. There are concerns that the current level of fishing may be unsustainable. In September and October 1998, CSIRO Division of Marine Resources surveyed the shallow reefs (0-15 m deep) and shoal areas (15-50 m deep) of the MOU74 Box area and Little Area A to the north. Its purpose was to assess the status of the reef resources in the area, and the environment that supports them. Fieldwork for the survey was completed on 10 October 1998. Overall, the sedentary marine living resources on the shallow reefs were heavily depleted with the high-value species over-exploited and the lower value species probably either fully or over-exploited. Despite the low density, there appears to be a sustained fishing effort by Indonesian fishers in the area. A drastic reduction in effort would be required to allow for a recovery of the higher value species, and to protect other species from severe depletion. The exception is Ashmore Reef, where there were significant populations of most target species. However, there is most likely some illegal fishing occurring on Ashmore Reef and there is clear evidence of exploitation of at least the high-value resources. The nature of these fisheries and the depleted state of the other reefs in the MOU74 Box suggests that the remaining resources on Ashmore Reef could be quickly depleted if the protection currently given to the reef is not maintained and possibly enhanced. For many reasons, including the potential for recruitment of larvae to depleted reefs, it is important that these populations are protected. Year round protection of the resources on Ashmore Reef should be considered. This record describes the following survey data for the Timor MOU74 Box: • Classified satellite habitat map for Scott and Seringapatam Reefs. • Classified satellite habitat map for Ashmore, Hibernia and Cartier Reefs.

  • This flythrough highlights canyon environments within the Gascoyne Marine Park offshore northwestern Australia. The Cape Range Canyon is a relatively narrow, linear canyon that initiates on the continental slope, but is connected to the shelf via a narrow channel. The walls of the canyon are steep and reveal a history of slumping and retrogressive failure, that have broadened the canyon over time. The floor contains a series of deep plunge pools, indicative of the action of sediment-laden turbidity currents in further eroding this canyon. Epibenthos within the canyons was relatively sparse and likely regulated by disturbance associated with sedimentation in the canyons. Rock overhangs often supported the highest densities of benthic suspension feeders, including glass sponges, octocorals, and ascidians. Bathymetry data and seafloor imagery for this flythrough was collected by the Schmidt Ocean Institute during survey FK200308. Funding was provided by Schmidt Ocean Institute, Geoscience Australia, the Australian Government’s National Environmental Science Program (NESP) Marine Biodiversity Hub, the Director of National Parks, and the Foundation for the WA Museum through a Woodside Marine Biodiversity Grant.

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    Geoscience Australia has completed the first phase of an areal map of Australia's coastal geomorphological units. Utilising pre-existing GIS datasets procured from local, state and federal government agencies, this national scale map conforms to a coastal geomorphology classification scheme developed at Geoscience Australia. Phase one consists of a geodatabase containing a series of state wide feature datasets that have been reclassified into the national coastal geomorphology classification scheme.

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    This database contains information about the distribution of 10 different types of sea floor sediment in the Australian region. It was derived from data collected and mapped by the Ocean Sciences Institute, University of Sydney.

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    The Oceanic Shoals survey (SOL5650, GA survey 339) was conducted on the R.V. Solander in collaboration with Geoscience Australia, the Australian Institute of Marine Science (AIMS), University of Western Australia and the Museum and Art Gallery of the Northern Territory between 12 September - 5 October, 2012. This dataset comprises an interpreted geomorphic map. Interpreted local-scale geomorphic maps were produced for each survey area in the Oceanic Shoals Commonwealth Marine Reserve (CMR) using multibeam bathymetry and backscatter grids at 2 m resolution and bathymetric derivatives (e.g. slope; 1-m contours). Six geomorphic units; bank, depression, mound, plain, scarp and terrace were identified and mapped using definitions suitable for interpretation at the local scale (nominally 1:10 000). Maps and polygons were manual digitised in ArcGIS using the spatial analyst and 3D analyst toolboxes. For further information on the geomorphic mapping methods please refer to Appendix N of the post-survey report, published as Geoscience Australia Record 2013/38: Nichol, S.L., Howard, F.J.F., Kool, J., Stowar, M., Bouchet, P., Radke, L., Siwabessy, J., Przeslawski, R., Picard, K., Alvarez de Glasby, B., Colquhoun, J., Letessier, T. & Heyward, A. 2013. Oceanic Shoals Commonwealth Marine Reserve (Timor Sea) Biodiversity Survey: GA0339/SOL5650 Post Survey Report. Record 2013/38. Geoscience Australia: Canberra. (GEOCAT #76658).

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    The data set provides outlines for the maximum extent of geomorphic units for the North West Marine Region. The dataset is clipped from Geoscience Australia’s original Geomorphic Features of Australia’s Exclusive Economic Zone (EEZ) to the East Marine Region extent. These data were compiled as part of Geoscience Australia’s integrated digital information system to provide improved accessibility and knowledge relating to the environmental management of Australian’s oceans resources. The geomorphic units are to be used as surrogates for benthic habitats and can be best applied to the construction of bioregionalisations of the seabed. The data set also includes the name of units in the attribute table, where known, the source(s) of the names, feature codes, province codes, as well as the area and perimeter of each unit. The data are accompanied by Geoscience Australia Record 2003/30. Dataset has been updated (2006) to correct errors in original file.

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    The Petrel Sub-basin Marine Environmental Survey GA-0335, (SOL5463) was undertaken by the RV Solander during May 2012 as part of the Commonwealth Government's National Low Emission Coal Initiative (NLECI). The survey was undertaken as a collaboration between the Australian Institute of Marine Science (AIMS) and GA. The purpose was to acquire geophysical and biophysical data on shallow (less then 100m water depth) seabed environments within two targeted areas in the Petrel Sub-basin to support investigation for CO2 storage potential in these areas. This dataset comprises an interpreted geomorphic map. Interpreted local-scale geomorphic maps were produced for each survey area in the Petrel Sub-basin using multibeam bathymetry and backscatter grids at 2 m resolution and bathymetric derivatives (e.g. slope; 1-m contours). Five geomorphic units; bank, plain, ridge, terrace and valley, were identified and mapped using definitions suitable for interpretation at the local scale (nominally 1:10 000). Maps and polygons were manual digitised in ArcGIS using the spatial analyst and 3D analyst toolboxes.

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    Providing accurate maps of coral reefs where the spatial scale and labels of the mapped features correspond to map units appropriate for examining biological and geomorphic structures and processes is a major challenge for remote sensing. The objective of this work is to assess the accuracy and relevance of the process used to derive geomorphic zone and benthic community zone maps for three western Pacific coral reefs produced from multi-scale, object-based image analysis (OBIA) of high-spatial-resolution multi-spectral images, guided by field survey data. Three Quickbird-2 multi-spectral data sets from reefs in Australia, Palau and Fiji and georeferenced field photographs were used in a multi-scale segmentation and object-based image classification to map geomorphic zones and benthic community zones. A per-pixel approach was also tested for mapping benthic community zones. Validation of the maps and comparison to past approaches indicated the multi-scale OBIA process enabled field data, operator field experience and a conceptual hierarchical model of the coral reef environment to be linked to provide output maps at geomorphic zone and benthic community scales on coral reefs. The OBIA mapping accuracies were comparable with previously published work using other methods; however, the classes mapped were matched to a predetermined set of features on the reef.

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    This record describes a single aggregated dataset of the geomorphic habitat environment (facies) for Australia's 7 states and territories: New South Wales, Victoria, Tasmania, Queensland, Northern Territory, South Australia, Western Australia. The classification system contains 12 easily identifiable and representative environments: Barrier/back-barrier, Bedrock, Central Basin, Channel, Coral, Flood- and Ebb-tide Delta, Fluvial (bay-head) Delta, Intertidal Flats, Mangrove, Rocky Reef, Saltmarsh/Saltflat, Tidal Sand Banks (and Unassigned). These types represent habitats found across all coastal systems in Australia. For the New South Wales region, 134 coastal waterways are described. Most of the estuaries of New South Wales are under intense land use pressure with approximately 80% of the State's population living near an estuary (NSW Dept of Land and Water Conservation) For the Victorian region, 54 coastal waterways are described. Most of the 54 coastal waterways have a "Modified" environmental condition (as opposed to "Near Pristine"), according to the National Land and Water Resources Audit definition. For the Tasmanian region, 88 coastal waterways are described. The majority of near pristine estuaries in Tasmania are located in the south and west of the State and on Cape Barren Island, according to the Department of Primary Industries, Water and Environment. For the Queensland region, 213 coastal waterways are described. Southern and central Great Barrier Reef lagoon coasts have a broad spectrum of river, tide and wave- dominated estuaries. For the Northern Territory region, 63 coastal waterways are described. Estuaries on the northern Arnhem Land, Gulf of Carpentaria coasts are predominantly tide-dominated estuaries, which vary greatly in size and floodplain characteristics. For the South Australia region, 36 coastal waterways are described. Most of the 36 coastal waterways have a "Modified" environmental condition (as opposed to "Near Pristine"), according to the National Land and Water Resources Audit definition. For the Western Australia region, 103 coastal waterways are described. Western Australia has a diverse range of Estuaries due to different climates. Ranging from mostly "near pristine" and tide influenced estuaries in the north to "near pristine" wave dominated estuaries in the southwest region.

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    This data presents the results of seabed mapping and habitat classification surveys completed in Darwin Harbour during 2011 and 2013 as part of the Northern Territory Government's marine habitat mapping program. This research is a collaboration between Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS), the Department of Land Resource Management (DLRM) and the Darwin Port Corporation. Key objectives are to: - Produce detailed maps of the bathymetry and derived parameters such as slope and rugosity, - Classify the seabed into areas of hard and soft substrate, and, - Produce seabed habitat maps (or seascapes). Key outcomes from the surveys include: 1. Improved understanding of the seabed of Darwin Harbour. The main seabed geomorphic features identified in Darwin Harbour include banks, ridges, plains and scarps, and a deep central channel that divides into smaller and shallower channels. Acoustically hard substrates are found mostly on banks and are associated with rocky reef and sponge gardens, and are often overlain by a thin veneer of sandy sediment. In contrast, plains and channels are characterised by acoustically soft substrates and are associated with fine sediments (mud and sand). 2. Classification of physical seabed properties to produce a Seascape Map for Darwin Harbour. Six seascape classes (potential habitats) were derived using an Iterative Self Organising (ISO) unsupervised classification scheme. These six classes are related to statistically unique combinations of seabed substrate, relief, bedform and presence of sediment veneer (quite often inferred from presence of epibenthic biota).