Adelaide

The volume reported in the water accounting statement (39,800 ML) represents groundwater extraction:

• for irrigation outside the Northern Adelaide Plains Prescribed Wells Area (PWA), Barossa Prescribed Water Resource Area and McLaren Vale PWA
• by major industries in metropolitan Adelaide
• from the T1 aquifer in the Northern Adelaide Plains PWA and from the Dry Creek PWA under the Penrice Exemption to the Natural Resources Management Act 2004.

The groundwater extraction during 2009–10 is itemised by purpose and area in the table below.

Data source

South Australian Department for Water (DFW): e-NRIMS Geographic Information System (GIS) database, internal database and data from an unpublished field survey.

Data provider

South Australian Department for Water

Method

Irrigation – Western Mt Lofty Ranges and Central Adelaide

The ‘global application’ method (Teoh 2002) was used to estimate unmetered groundwater extraction for irrigation. A spatial disaggregation technique was used to assign areas of irrigated land to a particular water source. The global application method was based on the crop application rates from Water Use on Australian Farms 2008–09 in the Adelaide and Mount Lofty Ranges Natural Resource Management region (ABS 2010c) and the area of irrigated land calculated from a GIS land use layer from SA Water’s e-NRIMS geodatabase. The irrigated area calculated from the GIS land use layer was reduced by 29% to be consistent with the area reported in the Australian Bureau of Statistics publication. For Central Adelaide, the area of irrigated land and crop type were obtained from a field survey (DFW, unpublished data, 2010) and used to fill gaps in the GIS land use layer.

Industrial use – metropolitan Adelaide

Information on annual groundwater extraction by major industrial users within metropolitan Adelaide was sourced from a report on metropolitan Adelaide groundwater model (Zulfic et al. 2008).

Industrial use – Penrice exemption

Industrial groundwater extraction associated with the Penrice exemption was:

• directly requested from industries extracting groundwater from wells in the Dry Creek PWA
• sourced from an internal Department for Water database covering groundwater extraction within the geographic boundary of the Northern Adelaide Plains PWA, but covered by the Penrice exemption to the Natural Resources Management Act.

Uncertainty

Ungraded

Assumptions, approximations and caveats/limitations

Irrigation extraction

This method is based on the following assumptions:

• The area of irrigated land is accurately represented by 71% of the area recorded as Class 4—Production from irrigated agriculture and plantations (Australian Land Use and Management [ALUM] classification) in the 2007–08 land use layer.
• Irrigated land from the GIS land use layer within 500m of one type of water source (SA Water pipelines, other reticulated supplies, dams with a capacity greater than 5ML or bores) rely solely on that water source.
• Irrigated land within 500m of SA Water pipelines was assumed to preferentially use the other water sources over SA Water.
• Irrigated land located within 500m of multiple water sources (other than SA Water pipelines) rely evenly on each water source.
• Irrigation application rates were unchanged since 2008–09.
• Water lost through evaporation after metering was considered negligible.
• A bore with attributes suggesting that it was not operational for water extraction (e.g. exploration and decommissioned) is assumed to be used for irrigation providing it meets the other conditions of this method.

Industrial extraction

The volume reported in the water accounting statement only includes industrial groundwater extraction associated with major industries in metropolitan Adelaide and the Penrice exemption. A suitable method could not be found for estimating industrial groundwater extraction elsewhere.