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.

The Australian Maritime Jurisdiction of approximately 7,000,000 km2 has, at most, 25% of its seabed surveyed at high resolution. Since September 2001, under Commonwealth Policy on Spatial Data Access and Pricing, Intergovernmental Committee on Spatial Data Access and Pricing, the co-custodian of the bathymetry data collected within the Australian Marine Jurisdiction has been assigned to Geoscience Australia (GA). GA thus hosts various formats of raw as well as processed bathymetry datasets from multiple sensors, including multibeam sonar systems. The quality between datasets varies, depending on the objectives of the survey. As of January 2013, the multibeam sonar bathymetric coverage held by GA was acquired by 48 vessels, 26 different multibeam sonar systems in 9 different frequencies between 12 and 455 kHz. Consequently, GA has to deal with a variety of survey standards, making the post-processing and merging not efficient. The objective of this document is thus to provide standards and guidance to GA personnel and contractors who conduct multibeam data acquisition and processing during marine surveys to maximise consistency and efficiency. This document provides the most critical steps to multibeam acquisition and a mandatory checklist and deliverables. Specific details and tips for processing using Caris HIPS & SIPS software and Kongsberg EM series data are also provided in the appendix.

The Oceanic Shoals Commonwealth Marine Reserve (CMR) (>71,000 km2) is located in the Timor Sea and is part of the National Representative System of Marine Protected Areas of Australia. The Reserve incorporates extensive areas of carbonate banks and terraces that are recognised in the North and North West Marine Region Plans as Key Ecological Features (KEFs). Although poorly studied, these banks and terraces have been identified as potential biodiversity hotspots for the Australian tropical north. As part of the National Environment Research Program Marine Biodiversity Hub, Geoscience Australia in collaboration with the Australian Institute of Marine Science undertook a marine biodiversity survey in 2012 to improve the knowledge of this area and better understand the importance of these KEFs. Amongst the many activities undertaken, continuous high-resolution multibeam mapping, video and still camera observations, and physical seabed sampling of four areas covering 510 km2 within the western side of the CMR was completed. Multibeam imagery reveals a high geomorphic diversity in the Oceanic Shoals CMR, with numerous banks and terraces, elevated 30 to 65 m above the generally flat seabed (~105 m water depth), that provide hard substrate for benthic communities. The surrounding plains are characterised by fields of depressions up to 1 m deep (pockmarks) formed in soft silty sediments that are generally barren of any epibenthos (Fig .1). A distinctive feature of many pockmarks is a linear scour mark that extends several tens of metres (up to 150 m) from pockmark depressions. Previous numerical and flume tank simulations have shown that scouring of pockmarks occurs in the direction of the dominant near-seabed flow. These geomorphic features may therefore serve as a proxy for local-scale bottom currents, which may in turn inform on sediment processes operating in these areas and contribute to the understanding of the distribution of biodiversity. This study focused on characterising these seabed scoured depressions and investigating their potential as an environmental proxy for habitat studies. We used ArcGIS spatial analyst tools to quantify the features and explored their potential relationships with other variables (multibeam backscatter, regional modelled bottom stress, biological abundance and presence/absence) to provide insight into their development, and contribute to a better understanding of the environment surrounding carbonate banks. Preliminary results show a relationship between pockmark types, (i.e. with or without scour mark) and backscatter strength. This relationship suggests some additional shallow sub-surface control, mainly related to the presence of buried carbonate banks. In addition, the results suggest that tidal flows are redirected by the banks, leading to locally varied flow directions and 'shadowing' in the lee of the larger banks. This in turn is likely to have an influence on the observed density and abundance of benthic assemblages.

This dataset contains backscatter homogeneity data from seabed mapping surveys on the Van Diemen Rise in the eastern Joseph Bonaparte Gulf of the Timor Sea. The survey was conducted under a Memorandum of Understanding between Geoscience Australia (GA) and the Australian Institute of Marine Science (AIMS) in two consecutive years 2009 (GA survey number GA-0322 and AIMS survey number SOL4934) and 2010 (GA survey number GA-0325 and AIMS survey number SOL5117). The surveys obtained detailed geological (sedimentological, geochemical, geophysical) and biological data (macro-benthic and infaunal diversity, community structure) for the banks, channels and plains to investigate relationships between the physical environment and associated biota for biodiversity prediction. The surveys also provide Arafura-Timor Sea, and wider northern Australian marine region context for the benthic biodiversity of the Van Diemen Rise. Four study areas were investigated across the outer to inner shelf. Refer to the GA record 'Methodologies for seabed substrate characterisation using multibeam bathymetry, backscatter, and video data: A case study for the Eastern Joseph Bonaparte Gulf, Northern Australia' for further information on processing techniques applied (GeoCat: 74092; GA Record: 2013/11).

This dataset contains seascape classification layer derived from bathymetry and backscatter, and their derivative from seabed mapping surveys in Darwin Harbour. The survey was undertaken during the period 24 June to 20 August 2011 by iXSurvey Australia Pty Ltd for the Department of Natural Resources, Environment, The Arts and Sport (NRETAS) in collaboration with Geoscience Australia (GA), the Darwin Port Corporation (DPC) and the Australian Institute of Marine Science (AIMS) using GA's Kongsberg EM3002D multibeam sonar system and DPC's vessel Matthew Flinders. The survey obtained detailed bathymetric map of Darwin Harbour. Refer to the GA record ' Mapping and Classification of Darwin Harbour Seabed' for further information on processing techniques applied (GeoCat: 79212; GA Record: 2015/xx)

This dataset contains multibeam sonar angular backscatter response curve data of area A1 from seabed mapping surveys on the Van Diemen Rise in the eastern Joseph Bonaparte Gulf of the Timor Sea. The survey was conducted under a Memorandum of Understanding between Geoscience Australia (GA) and the Australian Institute of Marine Science (AIMS) in two consecutive years 2009 (GA survey number GA-0322 and AIMS survey number SOL4934) and 2010 (GA survey number GA-0325 and AIMS survey number SOL5117). The surveys obtained detailed geological (sedimentological, geochemical, geophysical) and biological data (macro-benthic and infaunal diversity, community structure) for the banks, channels and plains to investigate relationships between the physical environment and associated biota for biodiversity prediction. The surveys also provide Arafura-Timor Sea, and wider northern Australian marine region context for the benthic biodiversity of the Van Diemen Rise. Four study areas were investigated across the outer to inner shelf. Refer to the GA record 'Methodologies for seabed substrate characterisation using multibeam bathymetry, backscatter, and video data: A case study for the Eastern Joseph Bonaparte Gulf, Northern Australia' for further information on processing techniques applied (GeoCat: 74092; GA Record: 2013/11).

Geoscience Australia carried out marine surveys in southeast Tasmania in 2008 and 2009 (GA0315) to map seabed bathymetry and characterise benthic environments through observation of habitats using underwater towed video. Data was acquired using the Tasmania Aquaculture and Fisheries Institute (TAFI) Research Vessel Challenger. Bathymetric mapping was undertaken in seven survey areas, including: Freycinet Pensinula (83 sq km, east coast and shelf); Tasman Peninsula (117 sq km, east coast and shelf); Port Arthur and adjacent open coast (17 sq km); The Friars (41 sq km, south of Bruny Island); lower Huon River estuary (39 sq km); D Entrecastreaux Channel (7 sq km, at Tinderbox north of Bruny Island), and; Maria Island (3 sq km, western side). Video characterisations of the seabed concentrated on areas of bedrock reef and adjacent seabed in all mapped areas, except for D Entrecastreaux Channel and Maria Island. The "challenger" folder contains processed multibeam backscatter data of the South East Tasmania Shelf. The SIMRAD EM3002 multibeam backscatter data were processed using the CMST_GA MB Process, a multibeam processing toolbox codeveloped by Geoscience Australia and Curtin University of Technology.

This dataset contains hardness classification data from seabed mapping surveys on the Van Diemen Rise in the eastern Joseph Bonaparte Gulf of the Timor Sea. The survey was conducted under a Memorandum of Understanding between Geoscience Australia (GA) and the Australian Institute of Marine Science (AIMS) in two consecutive years 2009 (GA survey number GA-0322 and AIMS survey number SOL4934) and 2010 (GA survey number GA-0325 and AIMS survey number SOL5117). The surveys obtained detailed geological (sedimentological, geochemical, geophysical) and biological data (macro-benthic and infaunal diversity, community structure) for the banks, channels and plains to investigate relationships between the physical environment and associated biota for biodiversity prediction. The surveys also provide Arafura-Timor Sea, and wider northern Australian marine region context for the benthic biodiversity of the Van Diemen Rise. Four study areas were investigated across the outer to inner shelf. Refer to the GA record 'Methodologies for seabed substrate characterisation using multibeam bathymetry, backscatter, and video data: A case study for the Eastern Joseph Bonaparte Gulf, Northern Australia' for further information on processing techniques applied (GeoCat: 74092; GA Record: 2013/11).

This report is the first of three reports that provide the scientific analyses and interpretations resulting from a four-year collaborative habitat mapping program undertaken within the Darwin and Bynoe Harbour region by Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and the Northern Territory Government Department of Environment and Natural Resources (DENR). This 4 year program (2014-2018) aims to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline information and developing thematic habitat maps that will underpin future marine resource management decisions. This program was made possible through offset funds provided by the INPEX-operated Ichthys LNG Project to DENR, and co-investments from GA and AIMS.

Multibeam sonars provide co-located high-resolution bathymetry and acoustic backscatter data over a swath of the seafloor. Not only does backscatter response vary with incidence angles but it also changes with different seabed habitat types as well. The resulting imagery depicts spatial changes in the morphological and physical characteristics of the seabed that many use to relate to other dataset such as biology and sediment data for seabed habitat classification purposes. As a co-custodian of national bathymetry data, Geoscience Australia holds massive volumes of multibeam data from various systems including comprehensive collection from its own SIMRAD EM3002D multibeam sonar system. Consequently, Geoscience Australia is researching the application of acoustic backscatter data for seabed habitat mapping to assist with deriving an inventory of seabed habitats for Australia's marine jurisdiction. We present a procedure and a technique developed for our SIMRAD EM3002D multibeam sonar system to derive meaningful angular backscatter response curves. The ultimate goal of this excersie is to try to make use of the angular backscatter response curve that many believe is unique and is an intrinsic property of the seafloor for seabed habitat classification purposes. Adopting the technique intially developed by the Centre for Marine Science and Technology at Curtin University of Technology, Geoscience Australia has further improved these techniques to suits its own sonar system. Issues surrounding the production of the angular backscatter response curves and their solutions will be discussed. We also present results derived from multibeam data acquired in the Joseph Bonaparte Gulf, NT and from the Carnarvorn Shelf (Point Cloates), WA from aboard AIMS Research Vessel Solander. This includes potential use of the angular backscatter response curves for seabed classification and results from a simple analysis using the Kolmogrov-Smirnov goodness of fit.