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.

The purpose of this paper is to investigate and quantify the accuracy with which hydrological signals in the Murray-Darling Basin, southeast Australia can be estimated from GRACE. We assessed the extent to which the Earth's major geophysical processes contaminate the gravitational signals in the Basin. Eighteen of the world's largest geophysical processes which generate major gravitational signals (e.g. melting of the Greenland icesheet, hydrology in the Amazon Basin) were simulated and the proportion of the simulated signal detected in the Murray - Darling Basin was calculated. The sum of the cumulative effects revealed a maximum of ~4 mm (equivalent water height) of spurious signal was detected within the Murray - Darling Basin; a magnitude smaller than the uncertainty of the basin-scale estimates of changes in total water storage. Thus, GRACE products can be used to monitor broad scale hydrologic trends and variability in the Murray-Darling Basin without the need to account for contamination of the estimates from external geophysical sources.

We are often faced with uncertainty when making decisions – from trivial decisions such as whether to take an umbrella, or major decisions such as whether to buy that house. Appreciating the uncertainty in future conditions (‘will it rain today?’; ‘will house prices continue to go up?’) is crucial to making good decisions. This is no different for water resource managers, who need to make decisions on flood prevention, climate adaptation or coal resource developments. As scientists, we strive to inform decision-makers about uncertainties in a comprehensive, unbiased and transparent manner. In this paper, we discuss some of the challenges and approaches used to communicate uncertainty during our contributions to the Bioregional Assessments Programme, a federally funded research project to assess the potential impacts of coal resource development on water resources and water-dependent assets in eastern Australia. A first step in analysing potential impacts, is to identify the causal pathways that detail how development activities can possibly affect the groundwater and surface water systems, and how these changes might affect the economic, social and ecological functioning of a region. This conceptual model provides the framework for detailed geological, hydrogeological, hydrological and ecological modelling. Predictions have traditionally been made using a single deterministic model, a calibrated model that best fits the available observations. However, to assess the likelihood of potential impacts, we used a stochastic approach to create an ensemble of possible predictions (hundreds and thousands of possible answers) that are all consistent with the available observations. This results in a range or distribution of predictions. However, communicating the range of model results, as well as all of the complexities and underlying assumptions in a way that is relevant and accessible to decision-makers is very challenging. For bioregional assessments, we have worked with decision makers to improve communication of uncertainty using a consistent, calibrated language, tables, plots of the range of predictions and maps designed to convey probabilistic information in an intuitive manner. Further, model details and assumptions are documented in technical reports, and the data, models and predictions are made publicly available to increase transparency and reproducibility. The amount and technical detail of that information can be challenging for decision-makers to identify what is important and what is not. To support decision-makers, we use a qualitative uncertainty analysis to summarise the rationale for and effect on prediction of each major assumption. This table, in combination with a plain English discussion, allows readers to rapidly appreciate the limitations, as well as opportunities for further data collection or modelling. Bioregional assessments have highlighted the importance of early consultation with target audiences, which has enabled us to tailor the uncertainty communication products to decision-makers, as well as avoid the potential for biased interpretation of results, where decision-makers are drawn to the extremes. <b>Citation:</b> Peeters, L.J.M., Crosbie, R.S., Henderson, B.H., Holland, K., Lewis, S., Post, D.A., Schmidt, R.K., The importance of being uncertain, <i>Water e-Journal</i>, Vol 3, No.2, 2018. ISSN 2206-1991. https//doi.org/10.21139/wej.2018.006

Contains a medium scale vector representation of the topography of Australia. The data include the following themes: Hydrography - drainage networks including watercourses, lakes, wetlands, bores and offshore features; Infrastructure - constructed features to support road, rail and air transportation as well as built-up areas, localities and homesteads. Utilities, pipelines, fences and powerlines are also included; Relief - features depicting the terrain of the earth including 50 metre contours, spot heights, sand dunes, craters and cliffs; Vegetation - depicting forested areas, orchards, mangroves, pine plantations and rainforests; and Reserved Areas - areas reserved for special purposes including nature conservation reserves, aboriginal reserves, prohibited areas and water supply reserves.

The Environmental Attributes Database is a set of lookup tables supplying attributes describing the natural and anthropogenic characteristics of the stream and catchment environment that was developed by the Australian National University (ANU) in 2011 and updated in 2012. The data is supplied as part of the supplementary Geofabric products which is associated with the 9 second DEM derived streams and the National Catchment Boundaries based on 250k scale stream network. Please consult the spreadsheet below for details of the attributes and their source data. Version 1.1.5 corrects an error in the connectivity.lut table where the field ARTFBARIER for a subset of records did not correctly flag the presence of an artificial barrier up or downstream of the stream segment.

Mean monthly and mean annual areal actual, areal potential and point potential evapotranspiration grids. The grids show the evapotranspiration values across Australia in the form of two-dimensional array data. The mean data are based on the standard 30-year period 1961-1990. Gridded data were generated using the ANU (Australian National University) 3-D Spline (surface fitting algorithm). The grid point resolution of the data is 0.1 degrees ( approximately 10km). As part of the 3-D analysis process a 0.1 degree resolution digital elevation model (DEM) was used. Approximately 700 stations were used in the analysis, and all input station data underwent a high degree of quality control before analysis, and conform to WMO (World Meteorological Organisation) standards for data quality. Areal Actual ET is the ET that actually takes place, under the condition of existing water supply, from an area so large that the effects of any upwind boundary transitions are negligible and local variations are integrated to an areal average. Areal Potential ET is the ET that would take place, under the condition of unlimited water supply, from an area so large that the effects of any upwind boundary transitions are negligible and local variations are integrated to an areal average. Point Potential ET is the ET that would take place, under the condition of unlimited water supply, from an area so small that the local ET effects do not alter local airmass properties. It is assumed that latent and sensible heat transfers within the height of measurement are through convection only. The above definitions are based on those given by Morton (1983), but we have used the term areal potential ET for Mortons wet-environment ET and the term point potential ET for Mortons potential ET. Morton, F.I. (1983). Operational estimates of areal evapotranspiration and their significance to the science and practice of hydrology. Journal of Hydrology, 66: 1-76.

The 9 second DEM derived streams are a a fully connected and directed stream network produced in rastor and vector fomats by Australian National University. This product is the raster format, for the the vector product please refer to the Bureau of Meterology's Geofabric Website (http://www.bom.gov.au/water/geofabric/index.shtml). It is built upon the representation of surface drainage patterns provided by the GEODATA national 9 second Digital Elevation Model (DEM) Version 3 (ANU Fenner School of Environment and Society and Geoscience Australia, 2008).

The National Catchment Database is a linked set of spatial layers and associated attribute tables describing key elements of the surface water hydrology of the Australian continent at a map scale of about 1:250,000. It is built upon the representation of surface drainage patterns provided by the GEODATA national 9 second Digital Elevation Model (DEM) Version 3 (ANU Fenner School of Environment and Society and Geoscience Australia, 2008). The stream network and catchment boundaries contained within the database form foundation elements of the Bureau of Meteorology's Australian Hydrological Geospatial Fabric (Geofabric), the spatial framework that underpins the Australian Water Resources Information System (AWRIS) (http://www.bom.gov.au/water/geofabric/index.shtml). This database adds additional environmental attributes not available through the AHGF. The database contains Levels 1 (drainage divisions) and 2 (aggregated river basins group) National Catchment Boundaries (NCB) in raster format including NCB Pfafstetter coding. The Vector format is available from the Bureau's Geobraic website.

The National Catchment Database is a linked set of spatial layers and associated attribute tables describing key elements of the surface water hydrology of the Australian continent at a map scale of about 1:250,000. It is built upon the representation of surface drainage patterns provided by the GEODATA national 9 second Digital Elevation Model (DEM) Version 3 (ANU Fenner School of Environment and Society and Geoscience Australia, 2008). The stream network and catchment boundaries contained within the database form foundation elements of the Bureau of Meteorology's Australian Hydrological Geospatial Fabric (Geofabric), the spatial framework that underpins the Australian Water Resources Information System (AWRIS) (http://www.bom.gov.au/water/geofabric/index.shtml). This database adds additional environmental attributes not available through the AHGF. The National Drainage Basins delineate the entire catchment area of any outlet to the sea or inland sink based on the GEODATA 9 second DEM. Available in raster and vector formats.