Speewa GIS; River Murray Corridor Salinity Mapping and Interpretation Project

Brief description

This GIS data package contains airborne electromagnetic (AEM) datasets and interpreted data products for the Speewa survey area, as part of the River Murray Corridor (RMC) Salinity Mapping and Interpretation Project. The RMC project was undertaken between 2006 and 2010 to provide information on a range of salinity and land management issues along a 450 kilometre reach of the Murray River from the South Australian border to Gunbower, northwest of Echuca in Victoria. The Speewa survey area extends from Speewa south to Swan Hill.

This metadata briefly describes the contents of the data package. The user guide included in the package contains more detailed information about the individual datasets and available technical reports.

The main components in the package are: AEM data and images derived from a holistic inversion of the RMC RESOLVE AEM survey; a composite digital elevation model (DEM); a range of interpreted data products designed to map key elements of the hydrogeological system and salinity hazards using the AEM dataset; and a series of ESRI ArcGIS map documents.

The AEM data component consists of grids and images of modelled conductivity data derived from a holistic inversion of the RMC RESOLVE AEM survey. They include: layer conductivity grids below ground surface; depth slice grids representing the average conductivity of various regular depth intervals below ground surface; floodplain slice grids representing the average conductivity of various depth intervals relative to the elevation above or below a surface that approximates the River Murray floodplain; watertable slice grids representing the average conductivity of various intervals relative to the elevation above or below the regional watertable; and AEM cross sections of conductivity versus depth along each of the flight lines. The holistic inversion AEM data are derived from the 'River Murray Corridor RESOLVE AEM Survey, VIC & NSW, 2007 Final Data (P1141)', available as Geoscience Australia product number 67212 (GeoCat #67212).

The DEM data component consists of a 10 metre horizontal resolution composite DEM for the River Murray Corridor AEM survey area derived from airborne light detection and ranging (LiDAR) surveys, AEM surveys, and the shuttle radar topography mission (SRTM) survey.

The interpreted data component is organised into product themes to address salinity and land management questions and to map key elements of the hydrogeological system and salinity hazards. An ArcGIS map document is included for each product theme. The products include: Blanchetown Clay; conductive soils; flush zones; groundwater conductivity; stratigraphic extents and reliability; near surface conductive zones; near surface resistive zones; Parilla Sands; Quaternary alluvium; recharge; salt store; surface salt; vegetation health; and Woorinen Formation.

The RMC project was funded through the National Action Plan for Salinity and Water Quality with additional funding from the Lower Murray Catchment Management Authority (CMA), Mallee CMA, Goulburn-Murray Water and the Murray-Darling Basin Authority. The project was administered by the Australian Government Department of Agriculture, Fisheries and Forestry through the Bureau of Rural Sciences, now known as the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES). Geoscience Australia (GA) were contracted to provide geophysical services to manage the AEM system selection and data acquisition, and to process and calibrate the AEM data. The AEM survey was flown by Fugro Airborne Geophysical Services in 2007 using the helicopter-borne RESOLVE frequency domain system. The Cooperative Research Centre for Landscape Environments and Mineral Exploration was sub-contracted through GA to manage the interpretation and reporting component of the RMC project.

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Maintenance and Update Frequency: notPlanned

Statement: AEM data
The holistic inversion methodology used to generate the conductivity model data is described in Brodie and Sambridge (2006). Information on how the depth slice grids, floodplain slice grids and watertable slice grids were derived is included in Appendix 1 of the user guide for this data package.

The AEM survey data were acquired and processed by the airborne geophysical survey contractor, Fugro Airborne Surveys. Details of the acquisition and processing are described in Farquhar (2008) and available from ABARES publications.

DEM data
The merging of elevation datasets for the River Murray Corridor AEM project was undertaken by Geoscience Australia. The data compilation is described in Brodie (2008) and is available from ABARES publications.

Interpreted data products
The methods used to compile and customise AEM-based interpreted map products to address salinity and land management questions are described in Tan et al (2009). Tan et al (2009) is included in this data package and is also available from ABARES publications.

Additional metadata for some products are included in this data package, as described in the user guide.