Preliminary Assessment Extent (PAE) Arckaringa subregion v03

## **Abstract** 

This dataset and its metadata statement were supplied to the Bioregional Assessment Programme by a third party and are presented here as originally supplied.



This dataset was created for the Bioregional Assessment by the Government of South Australia, Department of Environment, Water and Natural Resources. The data presents the approach taken to develop a Preliminary Assessment Extent (PAE) for the Arckaringa subregion. This mapping and geospatial data, represent draft information presented to the Bioregional Assessment Team, which will be amended as required to support the Bioregional Assessment Programme. It is understood that the Arckaringa PAE will be subject to revisions as new ecological, hydrological and hydrogeological information and understandings become available.

## **Dataset History** 

This dataset was created for the Bioregional Assessment by the Government of South Australia, Department of Environment, Water and Natural Resources. See the attached document relating to the methodology and assumptions in PAE development for more information



The following methodology was followed to formulate the Arckaringa PAE:

- Extent of potential groundwater drawdown assumed at 210km around coal beds (refer Figure 3), based upon DEWNR conceptual modelling undertaken for the Pedirka Basin (refer Appendix A for summary of modelling methodology). Modelling of the Arckaringa basin is proposed be completed by late 2014 which may affect this assumption. This applied to the north and easterly direction from coal beds within the basin.

- Inferred 210km groundwater drawdown extent assumes potential for up to a 50 year Life of Mine (LOM) and large scale mining operations.

- Western and southern boundaries follow the Great Artesian Basin (GAB) and Arckaringa Basin boundaries taking the further boundary from coal beds to identify potential groundwater connectivity.

- 20km buffer boundary included as a contingency around known surface waters and groundwater drawdown extents.

-10 km buffer included where PAE intersects with fractured rock aquifer (FRA) extents.

- Inclusion of springs in close proximity to 210km radius from coal beds in an easterly direction based upon knowledge of DEWNR groundwater system.

- Entire Lake Eyre (north and south) boundary incorporated (from SA Waterbodies mapping).

- Phreatic surface information (See Figure 5) was utilised to identify connectivity to shallow groundwater potentially utilised by vegetation, which was identified up to a 10m depth, based upon decisions made by the Bioregional Assessment team for other PAEs.

- Tertiary sediments were excluded from consideration as a buffer to the GAB where they intersect with coal deposits as it was assumed direct impact to the tertiary sediments would occur should open cut mining activities occur.

Additional data sets and assumptions used to derive the PAE and gain an understanding of ecological, hydrological, hydrogeological and mining related features and values include the following:

- Arckaringa basin boundary (DEWNR Dataset), including outlier basin formations excluded from the PAE where outside of the GAB.

- DMITRE Mapped areas of economic coal beds (Coal beds).

- Exploration Licences (EL) as lodged with DMITRE.

- Known watercourses (surface water data) (DEWNR dataset).

- Springs locations (DEWNR dataset + national springs database compiled for the Recovery Plan by Fensham et al. 2005)).

- GAB springs of the Lake Eyre supergroup included with a 5km buffer around the point location to accommodate the extensive wetland and terrestrial ecosystems the spring support. It is noted that the impacts of drawdown on pressures would reduce further from the coal resource but recognising that there may be ecological dependencies between the springs.

- PAE along south-western boundary of Arckaringa Basin based upon extent of drawn down from coal beds with limited groundwater knowledge. Western boundary excluded based on absence of GAB groundwater.

- A potentiometric surface has been generated for the GAB aquifer (Cadna-owie Formation - Algebuckina Sandstone and equivalents) for the SA and NT portions of the GAB.

- Coal Beds outside of Arckaringa Geological Basin are excluded.

- 5km buffer around GAB springs (GAB Springs Database) has been smoothed where appropriate.

- Dry areas of the GAB were excluded as these areas do not have surface water connections with lease areas.

- Potential for mining related water diversions excluded from the assessment.

- Upstream watercourses would be excluded where no direct link from mining, where outside the extent of drawdown.

- That the alluvial groundwater systems are not connected to the GAB

## **Dataset Citation** 

"SA Department of Environment, Water and Natural Resources" (2014) Preliminary Assessment Extent (PAE) Arckaringa subregion v03. Bioregional Assessment Source Dataset. Viewed 07 February 2017, http://data.bioregionalassessments.gov.au/dataset/1a27370f-c2c4-48dd-9b7b-d034dd6fee33.

Tags: Arckaringa subregion, geoscientificInformation
Organization: Bioregional Assessment Program