<div>The Abbot Point to Hydrographers Passage bathymetry survey was acquired for the Australian Hydrographic Office (AHO) onboard the RV Escape during the period 6 Oct 2020 – 16 Mar 2021. This was a contracted survey conducted for the Australian Hydrographic Office by iXblue Pty Ltd as part of the Hydroscheme Industry Partnership Program. The survey area encompases a section of Two-Way Route from Abbot Point through Hydrographers Passage QLD. Bathymetry data was acquired using a Kongsberg EM 2040, and processed using QPS QINSy. The dataset was then exported as a 30m resolution, 32 bit floating point GeoTIFF grid of the survey area.</div><div>This dataset is not to be used for navigational purposes.</div>

This service has been created specifically for display in the National Map and the chosen symbology may not suit other mapping applications. The Australian Topographic web map service is seamless national dataset coverage for the whole of Australia. These data are best suited to graphical applications. These data may vary greatly in quality depending on the method of capture and digitising specifications in place at the time of capture. The web map service portrays detailed graphic representation of features that appear on the Earth's surface. These features include the administration boundaries from the Geoscience Australia 250K Topographic Data, including state forest and reserves.

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Airborne electromagnetic (AEM) methods for near-surface hydrogeological investigations have undergone significant improvements in the past 10-15 years, particularly in the development of calibrated systems designed for high-resolution groundwater and environmental investigations (Sorensen & Auken, 2004; Auken et al., 2006). Important advances have been also been made in the development of rapid computational methods for AEM inversion (e.g. Christensen, 2002; Christensen et al., 2009), enabling conductivity models to be available for integration into real-time, short-term hydrogeological investigations (Lawrie et al., 2012). The processing of AEM data and the presentation of electrical conductivity data as maps and sections is now routine, and particularly effective for regional mapping in shallow-dipping sedimentary environments (Lane, 2002; Lawrie et al., 2009, 2012). In Australia, the application of electromagnetic (EM) methods for hydrogeological investigation is made more complex by the highly salinized nature of many landscapes, which can also be often deeply and variably weathered. In many instances, the electrical conductivity distribution does not equate with formation (and/or hydrogeological) boundaries, but instead to a combination of groundwater salinity and formation composition and texture (Lawrie et al., 2000, 2009). Despite these additional challenges, AEM is the only broadacre technique that can detect and resolve key functional elements of near-surface groundwater systems (Spies & Woodgate, 2005). The complex electrical structure of Australia's near-surface landscapes and the presence of conductive layers and basement in many regolith terrains has necessitated the development of constrained inversion approaches that utilise a priori geological, hydrogeological and hydrogeophysical data (Green & Munday, 2004; Lane et al., 2004; Lawrie et al., 2012). Constrained inversions, combined with rigorous technology selection, and appropriate calibration and validation procedures have enabled the successful mapping of potential groundwater resources and salinity hazards in several floodplain environments (Walker et al., 2004; Lawrie et al., 2009, 2012; Christensen & Lawrie, 2012). Importantly, studies in Australia have also demonstrated that the benefits from new AEM technologies and constrained inversion modeling are maximised when these technologies are employed within multi-disciplinary, systems-based approaches to the analysis of problems (George et al., 2003). Systems-based approaches incorporate an understanding of landscape evolution and scale, utilise modern investigative approaches to the conceptualisation of groundwater systems, and incorporate data on mineralogy, petrophysics, hydrology, ecology, topography, hydrogeochemistry and hydrodynamics. Within this multi-disciplinary research framework, the power and long-term value of AEM-based datasets for groundwater management lies largely in providing stakeholders with a range of customized interpretation products derived from the integration of electrical conductivity data with other hydrogeological, hydrogeophysical and hydrochemical datasets (George et al., 2003; Lawrie et al., 2000, 2009, 2012). The Broken Hill Managed Aquifer Recharge (BHMAR) project, in western N.S.W., Australia, has built significantly on the principles, methodologies, experience and products developed for salinity mapping and management in Australia. This included, a staged approach to technology selection and survey design, and the use of a 4D systems approach to integrate

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The Early Cretaceous Gage Sandstone and South Perth Shale formations are a prospective reservoir-seal pair in the Vlaming Sub-basin. Plays include post-breakup pinch-outs in the Gage Sandstone with the South Perth Shale forming top seal. The Gage reservoir has porosities of 18-25% and permeabilities of 1-1340 mD. It was deposited in palaeotopographic lows of the Valanginian breakup unconformity and is the lowstand component of the thick deltaic South Perth (SP) Supersequence. To characterise the reservoir-seal pair, a detailed sequence stratigraphic analysis was conducted by integrating 2D seismic interpretation, well log analysis and new biostratigraphic data. Palaeogeographic reconstructions for the SP Supersequence were derived from mapping higher-order prograding packages and establishing changes in sea level and sediment supply. Higher resolution Gage reservoir reconstructions were based on seismic facies mapping. The Gage reservoir forms part of a sand-rich submarine fan system similar to model proposed by Richards et al (1998). It ranges from canyon confined inner fan deposits to middle fan deposits on a basin plain. Directions of sediment supply are complex, with major sediment contributions from a northern and southern canyon adjacent to the Badaminna Fault Zone. The characteristics of the SP Supersequence differ markedly between the northern and southern parts of the sub-basin due to variations in palaeotopography and sediment supply. Palaeogeographic reconstructions reveal a series of regressions and transgressions leading to infilling of the palaeo-depression. Palaeogeographic reconstructions for the SP Supersequence portray a complex early post-rift depositional history in the central Vlaming Sub-basin. The developed approach is applicable for detailed studies of other sedimentary basins. APPEA

Coastal aquifer vulnerability to seawater intrusion.

Spatially continuous data of environmental variables is often required for marine conservation and management. However, information for environmental variables is usually collected by point sampling, particularly for the deep ocean. Thus, methods generating such spatially continuous data by using point samples to estimate values for unknown locations become essential tools. Such methods are, however, often data- or even variable- specific and it is difficult to select an appropriate method for any given dataset. In this study, 14 methods (37 sub-methods) are compared using samples of mud content with five levels of sample density across the southwest Australian margin. Bathymetry, distance to coast, and slope were used as secondary variables. Ten-fold cross validation with relative mean absolute error (RMAE) and visual examination were used to assess the performance of these methods. A total of 1,850 prediction datasets were produced and used to assess the performance of the methods. Considering both the accuracy and the visual examination, we found that a combined method, random forest and ordinary kriging (RKrf), is the most robust method. No threshold in sample density was detected in relation to prediction accuracy. No consistent patterns were observed between the performance of the methods and data variation. The RMAE of three most accurate methods is about 30% lower than that of the best methods in previous publications, highlighting the robustness of the methods selected in this study. The limitations of this study were discussed and a number of suggestions were provided for further studies.

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Legacy product - no abstract available