Adelaide
17.8 Non-allocated diversions - urban water system

The volume reported (120,014 ML) was the volume of water harvested from runoff produced within the Adelaide region boundary in the 2010–11 year. The volume reported was the sum of volumes of water diverted from surface water to the urban water system, less the volume of River Murray water discharged to surface water from the urban water system.

Water is imported from the River Murray into the Adelaide region for urban water supply through the Mannum–Adelaide Pipeline, Murray Bridge–Onkaparinga Pipeline and the Swan Reach–Stockwell Pipeline. However, some of the water from these pipelines is released to surface water for transportation to urban water offtakes located further downstream.

For clarity of presentation and to distinguish between water harvested within the region and water imported from outside the region, the discharge to surface water and subsequent diversion from surface water of River Murray water was not reported in the water accounting statements.

The volume of water diverted from Adelaide's surface waters (that was harvested within the region) was calculated by subtracting the volume of water discharged from the River Murray pipes into the surface waters from the overall volume discharged to surface water.

The breakdown of surface water diversions reported here makes the assumption that all water imported from the River Murray is used in the year it is imported and not stored for later years.

SA Water: readings may be from either the Supervisory Control and Data Acquisition (SCADA) database or manual field instrument readings, stored in the MetDaily file.

Bureau of Meteorology.

The volume of water diverted from Adelaide's surface waters (that was harvested from runoff within the region) was calculated by subtracting the volume of water discharged from the River Murray pipes into surface water (32,025 ML) from the overall volume of water diverted from surface water to the urban water system (152,039 ML).

This calculation method makes the assumption that all water imported from the River Murray is used in the year it is imported and not stored for later years.

The uncertainty estimate was not quantified.

SA Water: readings may be from either the Supervisory Control and Data Acquisition (SCADA) database or manual field instrument readings, stored in the MetDaily file.

Bureau of Meteorology.

The volume of surface water diverted to the urban water system was calculated from metered inflows, metered diversions and mass balance calculations as summarised in the following table.

Surface water inflow to the urban water system in the 2010–11 year

Source of diversion	Quantification approach	Measured/calculated inflow (ML)
Little Para WTP inflow from Little Para River	Metered inflow	14,310
Myponga WTP inflow from Myponga River	Metered inflow	6,052
Gorge Weir diversion to Hope Valley Reservoir	Metered diversion	12,969
Millbrook Reservoir to Millbrook tanks	Metered diversion	16,073
Clarendon Weir diversion to Happy Valley Reservoir	Metered diversion	92,256
Barossa Weir diversion to Barossa Reservoir	Reservoir mass balance	10,379
Total		152,039

WTP = Water treatment plant

The volumes of water diverted from surface water to urban storages in the 2010–11 year were obtained from SA Water's SCADA database and/or MetDaily file.

Metered inflow data were obtained from SA Water's SCADA database and/or MetDaily file for the Little Para and Myponga Water Treatment Plants (WTP).

The volume of water diverted from the South Para River to the Barossa Reservoir was calculated using the mass balance calculation described in the following table.

Mass balance calculations used to determine diversion from Barossa Weir to Barossa Reservoir

Function	Component	Volume (ML)
	Reservoir outflow (Barossa WTP outflow x 1.05)	10,262
add	Evaporation	699
less	Precipitation	499
less	Reservoir initial storage	4,268
add	Reservoir end storage	4,185
equals	Reservoir inflow (diversion from Barossa Weir)	10,379

The Barossa, Happy Valley, Hope Valley and Onkaparinga Summit reservoirs are considered part of the urban water supply system. This is due to the four storages being located offstream, having minimal runoff and being used solely to service their respective WTPs.

• no groundwater loss
• no inflow
• assumed 5% loss through water treatment process.

The uncertainty estimate was not quantified. This calculation was done using broad assumptions. The uncertainty is estimated to be in the range of +/– 12.5%.

SA Water: readings may be from either the Supervisory Control and Data Acquisition (SCADA) database or manual field instrument readings, stored in the MetDaily file.

Bureau of Meteorology.

The volume of water discharged from the urban water system major pipelines to surface water in the Adelaide region in 2010–11 was determined by obtaining flow gauge measurements from the SA Water's SCADA database and/or MetDaily file.

Water is imported from the River Murray into the Adelaide region for water supply through the Mannum–Adelaide Pipeline, Murray Bridge–Onkaparinga Pipeline and the Swan Reach–Stockwell Pipeline. These pipelines transfer water from the Murray River to the Adelaide region. The water from these pipelines is released to surface water for transportation to urban water offtakes located downstream. The following table shows the locations of these releases and the volumes released in the 2010–2011 year.

Urban water discharge to surface water in the Adelaide region during the 2010–11 year

Source	Surface water release point	Volume (ML)
Swan Reach–Stockwell Pipeline	South Para River	4
Murray Bridge–Onkaparinga Pipeline	Onkaparinga River	13,424
Mannum–Adelaide Pipeline	River Torrens	5,254
Mannum–Adelaide Pipeline	Millbrook Reservoir	1,151
Millbrook tanks	Little Para Reservoir	12,192
Total		32,025

• This item does not include the water imported via the Mannum–Adelaide Pipeline for supply to Barossa Infrastructure Limited (BIL). This volume of water is reported at line item 12.6.
• For accounting purposes all imported water, and therefore water released to surface water, is assumed to be used in this reporting period.
  

The uncertainty estimate was not quantified.

This line item corresponds to 14.7.4 Allocation/claim diversion of regulated flows - urban water access entitlement/arrangement reported in the 2010 Account. In the 2011 Account the following changes were made, which caused the values of the 2009–10 year to be restated:

• Reclassification: in the 2010 Account, a water liability on the surface water store was recognised for surface water diversions to the urban water system. In the 2011 Account, no such water liability was recognised. SA Water's right to abstract surface water for urban water supply is described in the Water rights section of the Contextual information; however there is no entitlement or allocation that creates a water liability for the surface water store within the Adelaide region. This change did not affect the volume reported, but was a material change as it now ensures that the arrangements under which SA Water divert surface water for urban water supply are accurately reported.

• Reclassification: in the 2011 Account the Bureau of Meteorology reclassified major storages located off-channel as part of line item 3.1 urban water supply system because they are used for urban water supply only. This change affected some of the locations where surface water diversions to the urban water system were measured, which in turn resulted in a material change to the volume reported at this line item.

• Change in methodology: in the 2011 Account the volume reported for surface water diversions to urban water system did not include River Murray water imported into the Adelaide region and subsequently discharged to surface water (as described in the Supporting information note), whereas in the 2010 Account it did. This change was made to provide clarity of presentation and to distinguish between water harvested within the region and water imported from outside the region. This change resulted in a material change to the volume reported in the 2010 Account.

These changes are summarised in the following table. The restated comparative year volume is 118,564 ML.

Restatement of comparative year information for line item 17.8 Non-allocated diversions - urban water system

2010 Account line item name	Source of diversion	Volume at 30 June 2010 reported in 2010 Account (ML)	Value difference to volume reported due to reclassification (ML)	Value difference to volume reported due to change in methodology (ML)	Volume at 30 June 2010 reported in 2011 Account (ML)
14.7.4 Allocation/claim diversion of regulated flows - urban water access entitlement/arrangement	Little Para WTP inflow from Little Para River	14,683		(19,320)	118,564
	Myponga WTP inflow from Myponga River	5,586
	Happy Valley WTP inflow from Happy Valley Reservoir	66,651	(66,651)
	Clarendon Weir diversion to Happy Valley Reservoir		80,297
	Anstey Hill WTP inflow from Millbrook tanks	25,118	(25,118)
	Millbrook Reservoir to Millbrook tanks		6,377
	Hope Valley WTP inflow from Hope Valley Reservoir	19,178	(19,178)
	Gorge Weir diversion to Hope Valley Reservoir		18,169
	Barossa WTP inflow from Barossa Reservoir	12,899	(12,899)
	Barossa Weir diversion to Barossa Reservoir		12,772
	Summit Storage WTP inflow from Onkaparinga Summit Reservoir	5,533	(5,533)
TOTAL		149,648	(11,764)	(19,320)	118,564