Beetaloo Basin buffer extent


## **Abstract** 
The dataset was derived by the Geological and Bioregional Assessment Program from multiple source datasets. The source datasets are identified in the History field in this metadata statement. The processes undertaken to produce this derived dataset are described in the History field in this metadata statement.


## **Attribution** 
Geological and Bioregional Assessment Program


## **History** 
This boundary was developed in consultation with the Northern Territory Government and is informed by the principles described in the draft Northern Territory Strategic Regional Environmental Bioregional Assessment Framework.   For terrestrial ecosystems these are:

For the ecology domains of the SREBA, the boundary should be determined following consideration of the following spatial areas: 
•	biogeographical boundaries 
•	geological (sub)basin boundaries with the gas resource
•	encompass the spatial distribution of ecological values on which gas development in that region could feasibly have an impact, including predictable indirect impacts; and
•	include sufficient bioregional extent to provide adequate context to assess the significance of any potential impact.   
In general, these boundaries should correspond to IBRA sub-bioregions.  However, additional consideration should be given to:
•	where gas development can feasibly only occur in one part of a large region, sub-regional boundaries may be appropriate
•	where only a small portion of a bioregion overlaps the edge of a gas (sub)basin, that entire bioregion cannot be cost-effectively be incorporated in the SREBA, so only a portion of that subregion should be included 
•	where there is potential for significant downstream impacts from development (notably on the quality or quantity of ground- or surface water), the boundary may extend out of the bioregion where development will occur, likely following (sub)catchment boundaries.          

The principles for aquatic ecosystems are similar, with a stronger emphasis on catchment or sub-catchment boundaries, and the extent of underlying aquifers that support ground-water dependent ecosystems; and also noting the need to sensibly limit the spatial extent of the study  in relation to downstream catchment areas, especially where there is no feasible impact pathway.

These principles were applied to derive the proposed Beetaloo GBA extended region boundary, primarily based on the boundaries of the Birdum (STU3) and Newcastle (STU2) subregions of the Sturt Plateau Bioregion.  In order to explain where and why it deviates from these subregions boundaries, starting at the northern edge and moving counter clockwise:
-	the northern edge follows the bioregion boundary.  Importantly, this corresponds to the Roper River in the Mataranka springs area.  For this section, the boundary has been extended to capture the Mataranka Thermal Pools. The north western edge also captures the springs feeding toward the Flora River, but may need to check this and adjust slightly so that these GDEs are included
-	on the western edge, the boundary diverts from the bioregion and follows the boundary of the Daly and then Roper Drainage Basins, and then cuts southward to rejoin the southern boundary of the Newcastle subregion.  This pragmatically exclude some of the most western extent of STU3 and STU2, which are geographically distant from the gas basin, and which are unlikely to add useful regional context to any of the ecology values. The GDE’s on the King River in the northwest have been included within the boundary.
-	It is considered essential to include Lake Woods in the study area, so a portion of the boundary of Mitchell Grass Downs (MGD2) is used to do this. The boundary then cuts across the top of the Mitchell Grass Downs to rejoin the STU2 boundary
-	The boundary cuts north to meet and use the western boundary of the McArthur River Basin – this excludes the most eastern extent of STU2, for similar reasons as above for excluding the most western extent
-	In the eastern section, the most easterly extent of the Beetaloo sub-basin just enters the Gulf Fall Bioregion.  This is ecologically very different to the Sturt Plateau, and so the requirement to sample in this area needs to be sensibly constrained.  A 20km buffer from the edge of the gas basin.  The boundary therefore encompasses the headwaters of some drainages that flow into the Limmen and Roper Rivers.   
-	The boundary then follows the STU bioregion boundary back to the northern edge.   This includes the upper reaches of the Strangways River and Maryfield Creek.

This dataset was derived using: NTGS Beetaloo Sub-basin boundary (A7710381-78BF-4E1F-B015-A9E874599F47), the DoEE Interim Biogeographic Regionalisation for Australia (Subregions - States and Territories) v. 7 (IBRA) (F83F319E-C369-4548-BBEC-3AAD7AB40AE8), and GBA Beetaloo basin GDE (E4C2B147-8338-4821-BC5E-DE300E9B6362) as its data sources.

Tags: Beetaloo sub-basin
Organization: Bioregional Assessment Program