The Surface Hydrology Points (Regional) dataset provides a set of related features classes to be used as the basis of the production of consistent hydrological information. This dataset contains a geometric representation of major hydrographic point elements - both natural and artificial. This dataset is the best available data supplied by Jurisdictions and aggregated by Geoscience Australia it is intended for defining hydrological features.

The AusHydro database provides a seamless surface hydrography layer for Australia at a nominal scale of 1:250,000. It consists of lines, points and polygons representing natural and man-made features such as water courses, lakes, dams and other water bodies. The natural water course layer consists of a linear network with a consistent topology of links and nodes that provide directional flow paths through the network for hydrological analysis. This network was used to produce the National 9 second Digital Elevation Model (DEM) of Australia (http://www.ga.gov.au/nmd/products/digidat/dem_9s.jsp). Surface Hydrology Dataset is an amalgamation of two primary datasets. The first is the hydrographic component of the GEODATA TOPO 250K Series 3 product released by Geoscience Australia in 2006 . The Series 3 dataset contains the following hydrographic features: canal lines, locks, rapid lines, spillways, waterfall points, bores, canal areas, flats, lakes, pondage areas, rapid areas, reservoirs, springs, watercourse areas, waterholes, water points, marine hazard areas, marine hazard points and foreshore flats.It also provides information on naming, hierarchy and perenniality. The dataset also contains Cultural and Transport features that may intersect with hydrography features. These include: Railway Tunnels, Rail Crossings, Railway Bridges, Road Tunnels, Road Bridges, Road Crossings, Water Pipelines. Refer to the GEODATA TOPO 250K Series 3 User Guide http://www.ga.gov.au/image_cache/GA8349.pdf for additonal information The second primary dataset is based on the GEODATA TOPO-250K Series 1 water course lines completed by Geoscience Australia in 1994, which has been supplemented by additional line work captured by the Australian National University during the production of the 9 second DEM to improve the representation of surface water flow. This natural watercourse dataset consists of directional flow paths and provides a direct link to the flow paths derived from the DEM. There are approximately 700,000 more line segments in this version of the data. AusHydro 1.0 uses the natural watercourse geometry from the ANU-enhanced Series 1 data, and the attributes (names, perenniality and hierarchy) associated with Series 3 to produce a fully attributed data set with topologically correct flow paths. The attributes from Series 3 were attached using spatial queries to identify common features between the 2 datasets. Additional semi-automated and manual editing was then undertaken to ensure consistent attribution along the entire network. WatercourseLines includes a unique identifier for each line segment (AusHydro-ID) which will be used to maintain the dataset, and to incorporate higher resolution datasets in the future. The AusHydro-ID will be linked to the ANUDEM-Derived (raster) streams through a common segment identifier, and ultimately to a set of National Catchments and Reporting Units (NCRU). Purpose Surface Hydrology Dataset is the reconciliation of the hydrological features in the two data sets to produce a single authoritative national stream network and water body data set suitable for hydrological analysis at national scales. It uses the natural watercourse geometry from the ANU-enhanced Series 1 data, and the attributes (names, perenniality and hierarchy) associated with Series 3 to produce a fully attributed data set with topologically correct flow paths.

A detailed analysis of aquifer systems in the Broken Hill Managed Aquifer Recharge priority areas has clarified our understanding of key components of the aquifer systems. Of the priority areas examined in detail, the aquifers located in the Darling Floodplain are considered to have the greatest potential for developing Managed Aquifer Recharge (MAR) options and for hosting significant volumes of previously undefined fresh and brackish groundwaters with low levels of allocation, thereby assisting the larger strategic effort aimed at identifying significant water-saving measures for the Darling River system.

Completion of a pilot study over the Namoi and Murrumbidgee catchments was part of the 2012-13 project schedule between Bureau of Meteorology (Bureau) and Geoscience Australia. The purpose of the pilot was to consolidate four years of research and development of the 1 second SRTM DEM, ANUDEM Streams, and National Catchment Boundaries to enable GA operational capacity to recreate the foundation datasets for Geofabric Phase 3 deliverables. This report is aimed to highlight how successfully the process has worked, issues that have arisen and identify and develop future modifications of the methodology to enable the production of Phase 3 Geofabric products. This professional opinion has been created for the Bureau and the Geofabric Steering Committees for review of Phase 3 of the Geofabric.

Subtitle: Behind the Scenes of Geofabric Version 3 Pilot & the Future of Geospatial Surface Water Information The Bureau of Meteorology's Australian Hydrological Geospatial Fabric (Geofabric) was established in 2008 as the spatial information database to support water accounting and resource assessment mandated under the Water Act 2007. Foundation layers for Geofabric versions 1 and 2 were developed from 1:250K streamline data and the 9 second resolution national DEM. The uses of the Geofabric data have expanded to new disciplines and have resulted in increased demand for finer national resolution. Version 3 of the Geofabric is now under development in a collaborative project between Geoscience Australia, CSIRO, Australian National University (ANU) and the Bureau of Meteorology. The foundation inputs for Geofabric version 3 are based on the integrated national surface hydrology dataset which uses the best available scale data from the jurisdictions and the 1 second resolution SRTM DEM. This significant enhancement presents both challenges and opportunities. This presentation at the Surveying & Spatial Sciences Institute (SSSI) ACT Region conference on 16 August 2013 aims to show the work being undertaken in the pilot areas of the Namoi and Murrumbidgee River Regions.

A collaborative field trial of the Quester-Tangent View Series 5 single beam acoustic benthic mapping system was recently conducted in Wallis Lake by Geoscience Australia and Quester Tangent Corporation. The survey involved acquisition of the acoustic backscatter data from the northern channels and basins of Wallis Lake. Quester-Tangent software (IMPACT v3) was used to classify acoustic echograms that returned from the lake bottom into statistically different acoustic classes, using principal components analysis. Six acoustically different substrate types were identified in the Wallis Lake survey area. Ground-truthing was undertaken to identify the sedimentological and biological features of the lake floor that influenced the shape of the return echograms. For each sample, measurements were made of grain size, wet bulk density, total organic carbon, CaCO3 content, and mass of coarse fraction (mainly shell) material. Statistical cluster analysis and multi-dimensional scaling were utilised to identify any physical similarities between groups of ground-truthing sites. The analysis revealed four distinct and mappable substrate types in the study area. The degree of association between acoustic classes and measured sediment parameters was also quantified. Cluster and MDS analysis revealed that, based on the parameters measured, the six acoustic classes were not uniquely linked to the sediment groups, suggesting that factors other than the sediment parameters alone are influencing the acoustic signal. The spatial interpretation of the Wallis Lake Quester-Tangent data represents the first quantification of non-seagrass habitats in the deeper areas of the lake, and provides a useful indicatior of benthic habitat diversity and abundance. For future studies, a more quantitative measure of faunal burrow size and density, and also other sedimentary bedforms, is recommended.

Geoscience Australia conducted a survey of lakebed (benthic) nutrient fluxes in St Georges Basin, November 2003. The objectives were to: 1. determine the nature of nutrient cycling between the sediment and overlying water; and 2. determine the implications of benthic nutrient fluxes for water quality in the estuary. The relevance to management of this work is that it gives an indication of the susceptibility of the estuary to eutrophication from increased nutrient loads from the catchment. The key findings of the study were: - St Georges Basin was mesotrophic to eutrophic at the time of the survey (spring) based on relatively high respiration rates and O2 demand in the sediments measured by in situ benthic chambers. - Respiration rates were linked to phytoplankton biomass (mainly diatoms) where local fluvial discharge of dissolved nutrients created enhanced primary productivity in the water column, which in turn enhanced mineralisation rates. - St Georges Basin had comparatively low denitrification efficiencies (less than 60%). - St Georges Basin is likely to be prone to eutrophication and may have little tolerance for increases in nutrient and organic matter from the catchment due to the low denitrification efficiencies.

In early autumn 2006 (14th March to 4th April), Geoscience Australia conducted a field survey to investigate the major processes controlling water quality in Wellstead Estuary, Gordon Inlet and Beaufort Inlet. This project aimed to address critical knowledge gaps in understanding the impact of sediment-water interactions on water quality in each estuary, in particular, to identify the major controls on nutrient abundance and availability. The impacts of sediment-water interactions on overall water quality took into account: 1. shallowness of the estuaries and long water residence time; 2. productivity of microbenthic algae; and 3. the type of aquatic plant growth. Recommendations for the future management of these estuaries included: 1. Reducing nitrogen loads from the catchments of Wellstead Estuary and Gordon Inlet, and reducing the phosphorus loads from the catchment of Beaufort inlet; 2. Monitoring the abundance of macroalgae in Wellstead Estuary, the abundance of macrophytes in Gordon Inlet and the water column Chl-a concentrations in Beaufort Inlet.

Geoscience Australia has conducted four surveys in the Swan River Estuary to investigate benthic nutrient fluxes and their impact on water quality. Surveys were undertaken in March 2000, March 2001, September 2001 and October 2006, and both the upper and lower sections of the estuary were sampled. This report details the findings of the most recent benthic nutrient survey (October 2006) and compares benthic fluxes at selected sites during all four surveys. During the October 2006 survey, very high nutrient fluxes were recorded in the upper estuary muddy sites. Combined with very low denitrification efficiencies, large sediment nutrient pool sizes and hypoxic bottom waters, these muds are a significant source of bioavailable nutrients to the water column. Between 2000 and 2006 there has been a significant increase in the amount of organic matter decomposition and nutrient release from the muddy sediments in the upper estuary. A similar pattern is observed in the central basin, however, the change is not as severe. The shallow sandy margins of the lower estuary are sites of photosynthetic production, however, these differ between benthic and pelagic production depending on the light attenuation. When light is available at the sediment surface benthic production is evident, when light penetration is insufficient to reach the sediment surface pelagic production is more evident.

In April 2005, Geoscience Australia (GA) conducted a field survey of the waterbodies of the Torbay catchment drainage system. The Torbay Catchment Group and the Western Australian Department of Environment commissioned this study in order to address critical knowledge gaps in their understanding of the major components of the nutrient budget. In particular, the role of benthic nutrient fluxes, their magnitude, and total benthic nutrient supply to the water column for phytoplankton growth. The waterbodies studied were Torbay inlet, Lake Powell, Marbellup Brook and Lake Manarup. The key findings of this study were: 1. the sediments are a major source of nutrients to the water column of all waterbodies; and 2. denitrification, nitrogen fixation and benthic photosynthesis are critical processes influencing overall water quality.