18.7 Extraction - other statutory rights
The volume reported (29,589 ML) represents non-licensed groundwater extractions from across the Adelaide region. Groundwater extractions reported here do not require a licence to extract and use water, instead the right to extract groundwater is provided for by sections 124(4), 124(6) 128, 132 and 164N of the Natural Resources Management Act 2004 (South Australia), (the Act).
For further information on these water rights see line item 33.1 Other statutory groundwater rights.
The volume reported included:
- groundwater extractions for stock and domestic purposes – described in sections 124(4) and 124(6) of the Act
- groundwater extractions for prescribed areas that are not currently managed under a water allocation plan – described in sections 128, 132 and 164N of the Act.
The following prescribed areas are not currently managed under a water allocation plan:
- Western Mount Lofty Ranges Prescribed Water Resources Area (PWRA)
- Central Adelaide Prescribed Wells Area (PWA)
- Kangaroo Flat portion of the Northern Adelaide Plains PWA
- Dry Creek PWA.
The volume reported excluded the Northern Adelaide Plains PWA where stock and domestic groundwater extractions are licensed.
Groundwater extractions itemised by groundwater management area, the section of the Act they fall under, the quantification approach and the purpose of the extractions are summarised in the following table.
|Area||Authorised by||Purpose||Measurement||Groundwater extraction volume (ML)|
|Central Adelaide PWA||Section 124(4) & 124(6)
||Stock and domestic||Planning figures||2,386|
|Adelaide region (excludes Central Adelaide PWA)||Section 124(4) & 124(6)
||Stock and domestic||Estimated||1,545|
|Western Mount Lofty Ranges PWRA & Central Adelaide PWA||Section 132||Irrigation||Estimated||19,641|
|Central Adelaide PWA||Section 132||Industrial||Assumed constant across years||3,120|
|Northern Adelaide Plains PWA – Kangaroo Flat||Section 164N||Irrigation||Metered extraction||1,010|
|Northern Adelaide Plains PWA and Dry Creek PWA||Section 128 & 164N||Industrial||Metered extraction||1,562|
|Central Adelaide PWA||Section 128||Fire-fighting purposes||Planning figures||5|
|Road construction purposes||Planning figures||320|
Kangaroo Flat portion of the Northern Adelaide Plains PWA section 164N right to extract
Metered extraction was obtained from the WILMA licensing database and linked to Drillhole Enquiry System records via the Unit ID to obtain the aquifer. All extraction is within the Tertiary T2 aquifer.
Northern Adelaide Plains PWA and Dry Creek PWA section 128 right to extract
Directly requested from industries extracting groundwater from wells in the Dry Creek PWA. Sourced from an internal South Australian Department for Water database covering groundwater extraction within the geographic boundary of the Northern Adelaide Plains PWA, but covered by a section 128 right to extract.
Central Adelaide PWA section 128 right to extract
Planning figures for practices covered by a section 128 authorisation (fire-fighting and road construction) were obtained from the planning document (Australian Groundwater Technologies 2011)
Western Mount Lofty Ranges PWRA and Central Adelaide PWA section 132 right to extract
The maximum potential groundwater demands were derived from the Western Mount Lofty Ranges PWRA survey of existing users and the Central Adelaide PWA survey of existing users.
Adjacent areas to the Western Mount Lofty Ranges PWRA within the Adelaide region are the Barossa PWRA and McLaren Vale PWA, which are managed under a water allocation plan. The combined groundwater extractions in the Barossa and McLaren Vale areas in the 2010–11 year were expressed as a percentage of allocations; the result was 27%.
An adjacent area to the Central Adelaide PWA within the Adelaide region is the Northern Adelaide Plains PWA, which is managed under a water allocation plan. Groundwater abstractions in the Northern Adelaide Plains in the 2010–11 year were expressed as a percentage of allocations; the result was 42%.
These adjustments were applied to the total potential demand for the Western Mount Lofty Ranges and the Central Adelaide PWA, respectively, to derive an estimated demand for 2010–11 of 19,641 ML.
Annual groundwater extraction by major industrial users within metropolitan Adelaide was isolated from the Central Adelaide PWA survey of existing users and estimated based on the assumption that extraction is constant throughout the year. Where possible, abstraction was referenced to an existing report on a metropolitan Adelaide groundwater model (Zulfic, Osei-Bonsu & Barnett 2008). The result was 3,120 ML.
Assumptions, Limitations, Caveats and Approximations
The extrapolation of abstraction in adjacent areas to groundwater abstractions the Western Mount Lofty Ranges PWRA and the Central Adelaide PWA only represents a rough estimate of annual non-allocated groundwater abstraction. The adjacent area's climate, management practices, mix of available water sources and water intensive industries are quite different to the area of interest. In particular the Central Adelaide PWA contains a significantly higher proportion of urban irrigation compared to the dominantly agricultural irrigation that occurs within the Northern Adelaide Plains PWA. In the Western Mount Lofty Ranges PWRA there is a far more diverse range of water intensive industries rather than dominantly viticulture as observed in the Barossa PWRA and McLaren Vale PWA.
The uncertainty is estimated to be in the range +/– 30–50%.
Stock and domestic water use
Unmetered groundwater extraction for stock and domestic purposes was calculated based on water demand within the Adelaide region (Bureau of Meteorology 2010). The volume excludes the Northern Adelaide Plains PWA in which stock and domestic extraction is metered and reported at line item 18.8.
Unmetered groundwater extraction for stock and domestic purposes was calculated as the sum of:
- stock demand
- domestic demand in rural areas.
Stock water use was calculated based on a method similar to the equation underlying the software package Damcat (Luke 1987; Farmer 2004). Australian Bureau of Statistics (ABS) stock numbers in 2009–10 for the Adelaide and Mount Lofty Ranges Natural Resource Management region were converted to dry sheep equivalents (DSEs) (Luke 1987; McLaren 1997). The seasonally adjusted DSE (for production patterns) and monthly average daily maximum temperatures for Adelaide (Kent Town) were used to calculate a stock drinking rate using an empirical equation (Luke 1987). The supply volume was increased based on advice from a farm water supply businessman, who suggested that 40% of the supply volume was lost in the delivering of water to stock (Dixon-Thompson, pers comm. 2010). The source of stock water was identified by spatially disaggregating grazing land use with a 500 m buffer of potential water sources as detailed in the following table.
|Available water source||Assumed water source|
|SA Water||SA Water||SA Water|
|SA Water and dam||SA Water||Dam|
|SA Water and bore||SA Water and metropolitan Adelaide groundwater||Bore|
|Dam and bore||50% surface and 50% groundwater||50% surface and 50% groundwater|
|SA Water, bore and dam||SA Water and metropolitan Adelaide groundwater||50% surface and 50% groundwater|
Domestic demand in rural areas
The volume of domestic water use was calculated by applying a demand of 190 kL/year (average annual residential water per household) to the number of dwellings assumed to have used bore water as their primary water source (National Water Commission 2010; 2011). The number of dwellings was revised upwards by 1.1% per year to represent population growth since the 2006 Census (Australian Bureau of Statistics 2010b). The sources of domestic water were identified by spatially disaggregating the areas in the ABS mesh block layer with a 500 m buffer around potential water sources. The proportion of mesh block area was used to derive the number of dwellings accessing each water source as detailed in the previous table.
Assumptions, Limitations, Caveats and Approximations
- Overall, the calculated volume of unmetered groundwater extraction for stock and domestic purposes was slightly less than the volumes stated in the relevant water allocation plans.
- The assumed water source differs for stock and domestic purposes due to different water quality requirements. It was assumed domestic purposes favour SA Water as a water supply, while SA Water would not typically supply stock water. The assumed water sources were identified by applying a 500 m buffer around each GIS feature (SA Water pipes, bores and dams). In the Adelaide metropolitan area, an estimate of domestic groundwater extraction was applied to the area otherwise serviced by SA Water.
This corresponds to the sub-categories of line item 16.4 Groundwater extraction under other statutory right. In the 2011 Account the following changes were made, which caused the values of the 2009–10 year to be restated:
- The presentation of the line items has changed since the 2010 Account: line items 16.4.1 Groundwater extraction - S&D basic right and 16.4.2 Groundwater extraction - other lumped basic rights in the 2010 Account were merged into a single line item 18.7 Extraction - other statutory rights.
- Improved data were made available for estimates of the stock and domestic groundwater extractions for the Central Adelaide PWA after the publication of the 2010 Account.
Restatement of the value published in the 2010 Account was made as the difference was material and increased the accuracy and comparability of the information provided to the users of the National Water Account. The changes and their respective values are detailed in the following table. The restated comparative year volume is 43,811 ML.
|2010 Account line item name||Volume at 30 June 2010 reported in 2010 Account (ML)||Value difference to volume reported due to improved data availability (ML)||Volume at 30 June 2010 reported in 2011 Account (ML)|
|16.4.1 Groundwater extraction - stock and domestic basic right||39,800||39,800|
|16.4.2 Groundwater extraction - other lumped basic rights||1,625||2,136||4,011|