As part of the Australian Government's National CO2 Infrastructure Plan (NCIP), Geoscience Australia has undertaken integrated assessments of selected offshore sedimentary basins for their CO2 storage potential. In March and April 2012, Geoscience Australia completed a seabed survey (GA0334) over two targeted areas (Area 1 and Area 2) of the Vlaming Sub-basin (Figure 1 1), as part of a larger study investigating the suitability of the Vlaming Sub-basin for geological storage of CO2. This document summarises the results and interpretation of seabed and shallow geological (to 30 m below the seabed) data acquired during survey GA0334 in the Vlaming Sub-basin. These data and their interpretations are being used to support the investigation of the Vlaming Sub-basin for CO2 storage potential.

The effective management of Darwin Harbour in Northern Australia is dependent upon accurate spatial information of seabed habitats that is required by multiple stakeholders. To develop this information, a combination of spatially continuous multibeam data, and targeted video and sediment data were used to classify the seabed and generate habitat maps. These data were acquired during collaborative surveys between Geoscience Australia, the Northern Territory Department of Land Resource Management (DLRM), the Australian Institute of Marine Science and the Darwin Port Corporation. A seascape analysis was used to classify the seabed, incorporating information from multibeam data and underwater video characterisations. We used the Iterative Self Organising Unsupervised Classification technique to combine the information from five variables to form a single classification showing potentially different seabed habitats. The 'probability of hard seabed' (p-rock) variable was derived by comparing the angular backscatter response of known areas of hard seabed to all other angular backscatter responses. We found that six habitat classes were statistically optimal and related to a unique combination of seabed substrate, relief, bedform, presence of a sediment veneer and presence of epibenthic biota and rock/reef. This presentation focuses on methods used to produce a continuous map of the harbour showing the distribution of multiple habitat types. We demonstrate the value of acoustic data for the characterisation of the seabed substrate. The resultant maps are being used by the Northern Territory DLRM to inform ongoing management of Darwin Harbour, with additional mapping planned for offshore areas and adjacent harbours in the region.

Darwin Harbour is the primary sea port for northern Australia, for which accurate information on the seabed is critical and required by multiple stakeholders. These stakeholders include the offshore energy industry, the fishing industry, and government authorities responsible for managing the harbour, in particular, the Port Authority. Darwin harbour is macrotidal with large areas of shallow (<10 m) subtidal and intertidal flats, dissected by bifurcating channels with localised areas of hardground. These hardground areas provide substrate for epibenthic communities. To support the informed management of Darwin Harbour, Geoscience Australia (GA), in collaboration with the Northern Territory Department of Land Resource Management (DLRM), the Australian Institute of Marine Science (AIMS) and the Darwin Port Corporation, conducted a multibeam survey of the harbour in 2011 on board MV Matthew Flinders. This was followed in 2013 by a physical sampling (sediments and video) survey by GA in collaboration with DLRM on board MV John Hickman. This paper presents results from those surveys with a focus on techniques used to produce a spatially continuous map of the harbour floor showing the distribution of hard and soft substrate types. The Darwin Harbour surveys acquired multibeam sonar data (bathymetry and backscatter) across 180 km2 gridded to 1 m resolution, 61 seabed samples and 35 underwater video observations to map and classify the seabed into habitats. Primary geomorphic features identified in Darwin Harbour include channels, banks, ridges, plains and scarps. Within the study area, acoustically hard substrates are associated with hard ground and relatively coarse seabed sediments. The hard grounds (rock, reef and coral gardens) are found mostly on banks and often overlain by a veneer of sandy sediment. In contrast, acoustically soft substrates are associated with fine sediments (mud and fine sand) that form the plains and channels. A seascape analysis was used to classify the seabed, incorporating information from multibeam data, underwater video characterisations and seabed hardness predictions. We used the Iterative Self Organising (ISO) Unsupervised Classification technique to combine the information from five variables (bathymetry, slope, rugosity, backscatter and probability of hard seabed (p-rock)) to form a single seabed habitat classification. The p-rock variable was derived by comparing the angular backscatter response of known areas of hard seabed to all other angular backscatter responses. We found that six habitat classes were statistically optimal based on the distance ratio measure. These six classes are related to a unique combination of seabed substrate, relief, bedform, presence of a sediment veneer and presence of epibenthic biota and rock/reef (hard substrate). The results presented here demonstrate the value of acoustic data for the characterisation of the seabed substrate that provides key habitats for benthic biota. This study also highlights the utility of the p-rock variable for habitat mapping at the level of distinguishing areas of hard seabed from soft sediment areas. The resultant seabed habitat maps are being used by the Northern Territory DLRM to inform ongoing management of Darwin Harbour, with additional mapping planned for offshore areas and adjacent harbours in the region.

Determination of an accurate groundwater balance for a region requires estimation of recharge and discharge rates and, where possible, knowledge of their spatial distribution. Where the value of the resource warrants it, detailed recharge and discharge studies are commissioned. These studies provide comprehensive empirical information on spatial and temporal variability of recharge, and the relationship between recharge rates and soil, regolith, landform and vegetation parameters. Where the value of the resource does not warrant detailed research, much cruder approaches (such as the estimation of recharge as a simple percentage of rainfall or the assumption that discharge is non-existent) are used. The CSIRO-led Recharge Discharge Mapping in Data Poor Areas Project jointly undertaken with Geoscience Australia (GA) developed a nationally consistent approach to recharge and discharge estimation for data poor areas which provide an intermediate solution between the use of simple approximations and the results of detailed field and modelling studies. Initially made available via GA's MapConnect website, the data layers in this dataset provide the means for hydrologists to populate the Recharge Estimation spreadsheet and the Discharge Estimation spreadsheet which may be sourced from CSIRO.

In May 2013, Geoscience Australia, in collaboration with the Australian Institute of Marine Science, undertook a marine survey of the Leveque Shelf (survey number SOL5754/GA0340), a sub-basin of the Browse Basin, on the AIMS research vessel, Solander. The survey provided seabed and shallow geological information to support an assessment of the CO2 storage potential of the Browse sedimentary basin. The basin, located on the Northwest Shelf, Western Australia, was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. The survey was undertaken under the Australian Government's National CO2 Infrastructure Plan (NCIP) to help identify sites suitable for the long term storage of CO2 within reasonable distances of major sources of CO2 emissions. The principal aim of the Leveque Shelf marine survey was to look for evidence of any past or current gas or fluid seepage at the seabed, and to determine whether these features are related to structures (e.g. faults) in the Leveque Shelf area that may extend to the seabed. The survey also mapped seabed habitats and biota to provide information on communities and biophysical features that may be associated with seepage. This research, combined with deeper geological studies undertaken concurrently, addresses key questions on the potential for containment of CO2 in the basin's proposed CO2 storage unit, i.e. the basal sedimentary section (Late Jurassic and Early Cretaceous), and the regional integrity of the Heywood Formation (the seal unit overlying the main reservoir).

This web service contains marine geospatial data held by Geoscience Australia. It includes bathymetry and backscatter gridded data plus derived layers, bathymetry coverage information, bathmetry collection priority and planning areas, marine sediment data and other derived products. It also contains the 150 m and optimal resolution bathymetry, 5 m sidescan sonar (SSS) and synthetic aperture sonar (SAS) data collected during phase 1 and 2 marine surveys conducted by the Governments of Australia, Malaysia and the People's Republic of China for the search of Malaysian Airlines Flight MH370 in the Indian Ocean. This web service allows exploration of the seafloor topography through the compilation of multibeam sonar and other marine datasets acquired.

This web service contains marine geospatial data held by Geoscience Australia. It includes bathymetry and backscatter gridded data plus derived layers, bathymetry coverage information, bathmetry collection priority and planning areas, marine sediment data and other derived products. It also contains the 150 m and optimal resolution bathymetry, 5 m sidescan sonar (SSS) and synthetic aperture sonar (SAS) data collected during phase 1 and 2 marine surveys conducted by the Governments of Australia, Malaysia and the People's Republic of China for the search of Malaysian Airlines Flight MH370 in the Indian Ocean. This web service allows exploration of the seafloor topography through the compilation of multibeam sonar and other marine datasets acquired.

As part of the Australian Tsunami Warning System Project (2005-09), the Attorney-General's Department funded Geoscience Australia to develop the national offshore Probabilistic Tsunami Hazard Assessment (PTHA). This assessment could then be used by Australian emergency managers in understanding the tsunami hazard to Australia. The national offshore PTHA considers the tsunami hazard posed to the entire Australian coast by tsunami caused by subduction zone earthquakes in the Indian and Pacific Oceans. These regions are known to have produced major tsunamigenic events External site link in recorded history and are the most likely sources of future events. The hazard maps are defined at a bathymetry water depth contour of 100m offshore. This normally falls outside of the Great Barrier Reef or other reef systems. The 100m depth contour is chosen because: Estimating the tsunami closer to the coast requires high resolution bathymetric data which does not always exist for the entire coast estimating the tsunami closer to the coast is a more computational and time intensive task. These maps help to identify the areas which are most likely to be at risk to damaging tsunami waves. However, they cannot be used directly to infer how far a tsunami will inundate onshore (inundation extent), how high above sea level they will reach on land (run-up), the extent of damage or any other onshore phenomena. To estimate the onshore tsunami impact, detailed bathymetry and topography of the specific region concerned is required for input to a detailed inundation model. The catalogue of tsunami events used to derive the national offshore PTHA can be used by emergency managers, researchers and individuals however to develop detailed inundation models at any onshore location.

Coastal communities in Australia are particularly exposed to coincident natural hazards, whereby tropical cyclones and extra-tropical storms cause damage to infrastructure and shorelines from severe wind, flood and storm surge. Because the climatic drivers of severe storms are stronger under certain conditions (e.g. during La Ni±a periods for tropical cyclones), these events can repeatedly impact the coast over periods of weeks to months. Historically, major episodes of beach erosion along southeast Australia have occurred during every decade over the last century, with the most severe in 1974 resulting from two extra-tropical storms in two months. <p>While the process of beach erosion is well understood in general terms, the response of a specific sector of coast to clustered storms may not be. For effective coastal management, this site specific knowledge becomes essential. Here we present a framework for integrating coastal geomorphology and coastal engineering approaches to model shoreline response to clustered storms at a spatial scale that can directly inform management agencies. We focus on two case study areas in southeast Australia, the beaches of the Adelaide metropolitan coast (South Australia) and Old Bar beach (central New South Wales) where erosion is a management priority. <p>For each site we adopt the coastal sediment compartment as the functional management unit, mapped for the Australian continent at multiple spatial scales, and use sub-surface information (boreholes, ground penetrating radar profiles) to estimate sediment volumes in the upper beach to foredune. These data are then used to inform shoreline response modelling linked to an event time series (observed and hind cast) as a separate project component. Future work includes assessment of `at-risk infrastructure at each site. This paper is a contribution to the Bushfire and Natural Hazard Cooperative Research Centre project Storm surge: Resilience to clustered disaster events on the coast.

In May 2013, Geoscience Australia, in collaboration with the Australian Institute of Marine Science, undertook a marine survey of the Leveque Shelf (survey number SOL5754/GA0340), a sub-basin of the Browse Basin. This survey provides seabed and shallow geological information to support an assessment of the CO2 storage potential of the Browse sedimentary basin. The basin, located on the Northwest Shelf, Western Australia, was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. The survey was undertaken under the Australian Government's National CO2 Infrastructure Plan (NCIP) to help identify sites suitable for the long term storage of CO2 within reasonable distances of major sources of CO2 emissions. The principal aim of the Leveque Shelf marine survey was to look for evidence of any past or current gas or fluid seepage at the seabed, and to determine whether these features are related to structures (e.g. faults) in the Leveque Shelf area that may extend to the seabed. The survey also mapped seabed habitats and biota to provide information on communities and biophysical features that may be associated with seepage. This research, combined with deeper geological studies undertaken concurrently, addresses key questions on the potential for containment of CO2 in the basin's proposed CO2 storage unit, i.e. the basal sedimentary section (Late Jurassic and Early Cretaceous), and the regional integrity of the Heywood Formation (the seal unit overlying the main reservoir). The survey collected one hundred and eleven seabed sediment samples that were analysed for their grain size, textural composition and carbonate content. This dataset includes the results of grain size measurements done by sieve analysis on seabed sediments.