The dataset was derived by the Bioregional Assessment Programme from multiple source datasets. The source datasets are identified in the Lineage field in this metadata statement. The processes undertaken to produce this derived dataset are described in the History field in this metadata statement.
The Preliminary Assessment Extent (PAE) is a spatial layer that defines the land surface area contained within a bioregion (and possibly outside) over which coal resource development may have potential impact on water-dependent assets and receptors associated with those assets (Barrett et al 2013). The Gloucester subregion is defined by the geological Gloucester Basin (Roberts et al., 1991). As this is a geological mapping unit, there has been no consideration beyond the subregion boundary of groundwater and/or surface water connection. From a groundwater perspective it is a closed system with groundwater discharging to lower portions of the landscape and being evaporated through riparian vegetation (Parsons Brinckerhoff, 2012a, pp. 30-31). Hence, as there is no groundwater connection to assets beyond the boundary of the Gloucester subregion, no further consideration of groundwater connectivity is required. The PAE of the Gloucester subregion is comprised of the union of the Gloucester subregion boundary and, to account for changes in surface water flows, 1 km buffer zones either side of the major rivers flowing from the northern component (to the outlet of the Gloucester River) and from the southern component to Port Stephens. It is assumed that water from rivers will be pumped a maximum of 1 km, hence the 1 km buffer around streams. The relative contributions to flow from various streams was examined using climate data and the Budyko framework to determine how far outside the bioregion the surface water might be significantly impacted by changes to the water balance within the bioregion.
Barrett DJ, Couch CA, Metcalfe DJ, Lytton L, Adhikary DP and Schmidt RK (2013) Methodology for bioregional assessments of the impacts of coal seam gas and coal mining development on water resources. A report prepared for the Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development through the Department of the Environment. Department of the Environment, Australia. Viewed 2 October 2014, http://iesc.environment.gov.au/publications/methodology-bioregional-assessments-impacts-coal-seam-gas-and-coal-mining-development-water.
Parsons Brinckerhoff (2012a) Phase 2 groundwater investigations - Stage 1 Gas Field Development Area: Gloucester Gas Project. Technical report by Parsons Brinckerhoff Australia Pty Limited for AGL Upstream Investments Pty Ltd. Parsons Brinckerhoff Australia Pty Limited, Sydney. Viewed 12 Aug 2013, http://agk.com.au/gloucester/assets/pdf/PB Gloucester Groundwater Report Phase 2 Text.pdf
Roberts J, Engel B and Chapman J (1991) Geology of the Camberwell, Dungog, and Bulahdelah 1:100 000 Geological Sheets 9133, 9233, 9333. New South Wales Geological Survey, Sydney.
The role of the PAE is to optimise research agency effort by focussing on those locations where a material causal link may occur between coal resource development and impacts on water dependent assets. The lists of assets collated by the Program are filtered for "proximity" such that only those assets that intersect with the PAE are considered further in the assessment process. Changes to the PAE such as through the identification of a different development pathway or an improved hydrological understanding may require the proximity of assets to be considered again. Should the assessment process identify a material connection between a water dependent asset outside the PAE and coal resource development impacts, the PAE would need to be amended.
The Gloucester subregion is defined by the geological Gloucester Basin (Roberts et al., 1991). As this is a geological mapping unit, there has been no consideration beyond the subregion boundary of groundwater and/or surface water connection. The PAE of the Gloucester subregion is comprised of the union of the Gloucester subregion boundary and, to account for changes in surface water flows, 1 km buffer zones either side of the major rivers flowing from the northern component (to the outlet of the Gloucester River) and from the southern component to Port Stephens. The Australian Hydrological Geospatial Fabric (Geofabric) - developed by the Bureau of Meteorology (2012) - was used to define a set of catchments that flow into and out of the northern and southern components of the Gloucester subregion. This process identified 13 subcatchments. Seven subcatchments define the north flowing rivers that comprise the Manning river basin, five subcatchments constitute the south flowing rivers that make-up the Karuah river basin, the remainder is the Wallamba River catchment. As the Wallamba River catchment (in which the town of Forster is located) is not hydrologically connected to surface water flowing from the Gloucester subregion, it is not considered further.
Two versions form the data set:
Gloucester_PAE_20130719.shp - originally defined area with doughnut (missing area completely contained within the bounding polygon) due to geological basin bnd.
Gloucester_PAE_for_map_aesthetics.shp - as above with doughnut removed.
Bioregional Assessment Programme (2013) GLO Preliminary Assessment Extent. Bioregional Assessment Derived Dataset. Viewed 13 March 2019, http://data.bioregionalassessments.gov.au/dataset/c0dba74a-feee-440f-a53a-ea31be8479a5.
Derived From Geofabric Hydrology Reporting Catchments - V2.1
Derived From Australian Coal Basins
Derived From Mean Annual Climate Data of Australia 1981 to 2012
Derived From Natural Resource Management (NRM) Regions 2010
Derived From Bioregional Assessment areas v01
Derived From Bioregional Assessment areas v02
Derived From GEODATA TOPO 250K Series 3
Derived From Australian Geological Provinces, v02
Derived From Gloucester Coal Basin
Derived From Geological Provinces - Full Extent