Adelaide
Resources and Systems

The purpose of this note is to provide a consolidated report on the surface water store within the region during the 2010–11 year. Information on all water flows to and from the surface water store are presented here, including between store flows and transfers that are not presented in the water accounting statements.

A description of the Adelaide region's surface water resources is provided in the Surface water section of the Contextual information.

The volume of the surface water asset included water held in surface water storages (1.1 Storages) and weirs (1.2 Unregulated river). The surface water asset excluded water in river channels, lakes and wetlands as these volumes could not be quantified in a way that was complete, neutral and free from material error, due to a lack of available data. The location of each surface water storage and weir in the Adelaide region, and the volume of water held in each of these storages as a percentage of active storage capacity at the end of the 2010–11 year, is shown in Figure 1.

The volume of water held in all storages within the Adelaide region increased by approximately 30% during the 2010–11 year (Table 1). Water held in storages, as a proportion of active storage capacity, increased from approximately 52% to 69% during the 2010–11 year.

The increase in surface water storage during the year is attributed to the increased inflows into the storages during the 2010–11 year, primarily driven by higher than average rainfall experienced throughout the period (refer to the Rainfall section of the Contextual information).

Table 1. Surface water store volume at the start and end of the 2010–11 year

1 Surface water	30 June 2011 ML	30 June 2010 ML
1.1 Storages	120,110	93,316
1.2 Unregulated river	460	437
1.4 Lakes and wetlands	–	–
Total	120,570	93,753

 


Figure 1. Location map of surface water storages within the Adelaide region. The volume of water held in each of these storages as a percentage of active storage capacity on 30 June 2011 for each storage is also shown.

Surface water inflows and outflows

Inflows to the surface water store were almost 50% greater than outflows from the surface water store during the 2010–11 year. A schematic diagram representing all the inflows and outflows associated with the surface water store in the Adelaide region is provided in Figure 2.

Figure 2. Schematic diagram of water inflows (blue arrows) and outflows (red arrows) for the surface water store within the Adelaide region during the 2010–11 year. Solid arrows indicate water transfers; dotted arrows indicate natural water movement; waved arrows indicate leakage. Line item numbers are provided next to the flows.

Table 2 shows volumes of inflows and outflows to and from the total surface water store: storages, rivers and weirs. Rainfall runoff provided the most significant contribution to surface water inflows, which is not surprising given that there is no inflow from upstream outside the region. Inflows to the surface water store via rainfall-runoff were also augmented by above-average rainfall experienced by southeastern Australia during the 2010–11 year. By comparison, all other surface water inflows were minor. Outflows from the surface water store were mainly due to diversions to the urban water system and outflow from rivers to sea.

Table 2. Volumes of inflows and outflows for the surface water store during the 2010–11 year

9 Surface water inflows	Volume (ML)
9.1 Precipitation on surface water	10,974
9.3 Groundwater discharge	72,148
9.4 Runoff to surface water	598,040
9.6 Overbank flood return to river channel	–
9.9 Discharge from urban water system	2,425
Total 9 Surface water inflows	683,587
17 Surface water outflows
17.1 Evaporation from surface water	15,283
17.2 River outflow from the region	305,853
17.3 Leakage to groundwater	–
17.4 Leakage to landscape
17.5 Overbank flood spilling	–
17.6 Diversions - other statutory rights	2,728
17.8 Non-allocated diversions - urban water system	120,014
17.11 Surface water allocation diversion	1,234
Total 17 Surface water outflows	445,112
Balancing item – surface water store	211,658
Change in surface water storage	26,817
Opening surface water storage	93,753
Closing surface water storage	120,570

Line items in italic indicate between-store flows, which are not presented in the water accounting statements as they occur within the region.

Diversions

Collectively, allocation diversions from the surface water store (line item 17.11) and surface water diversions representing other statutory rights (line item 17.6) accounted for only a very small portion (3,512 ML: < 3%) of surface water diversions in the Adelaide region during the 2010–11 year.

Allocation diversions of surface water currently only occur in the Barossa Prescribed Water Resources Area. These diversions are generally licensed for the purposes of irrigation or industrial use, and the actual volume diverted was approximately 45% of the allocated volume.

Surface water diversions representing other statutory rights occur throughout the Western Mount Lofty Ranges Area and are typically for irrigation purposes. 

The majority (120,014 ML: 97%) of surface water diversions in the Adelaide region during the 2010–11 year were surface water diversions to the urban water system (line item 17.8).

Figure 3 shows that surface water diversions have increased slightly in the 2010–11 year compared to the 2009–10 year, which is due to a small increase in surface water diversions to the urban water system. This result is surprising given that above-average rainfall may be expected to reduce demand on water resources, including surface water. Above-average rainfall has resulted in water restrictions being eased, which in turn may be responsible for promoting increased urban water use.

Figure 3. Graph of diversions from the surface water store within the Adelaide region during the 2010–11 year and the 2009–10 year for comparison

The balancing item volume represents the difference between the measured opening and closing balances of the surface water store, after physical inflows and outflows have been applied. This item is an indication of both the accuracy of the volumes reported and the degree to which the reported water flows represents a complete surface water store balance.

Table 3. Balancing item for the surface water store for the 2010–11 year

	Account	Volume (ML)
	Opening balance (30 June 2010)	93,753
add	Total 9 Surface water inflows (see Table 2)	683,587
less	Total 17 Surface water outflows (see Table 2)	445,112
less	Closing balance (30 June 2011)	120,570
	Balancing item – surface water store	211,658

The calculation of the water balance on the surface water store yielded a balance of 211,658 ML. This is approximately 170% of the total surface water store volume at the end of the 2010–11 year and 30% of the total surface water inflows during the 2010–11 year.

The balancing item for the surface water store is due to a combination of line items that were wholly or partly not quantified, and due to errors and uncertainty associated with the quantification methods. Items that were not quantified include evaporation from rivers (except at certain weirs) and some surface water/groundwater interactions.

A large component of the balancing item is likely to be attributed to the quantification of rainfall-runoff (line item 9.4). There is uncertainty associated with the meteorological inputs into the model and the model structure, estimated to be in the range of 10–20% (+/– 120,000 ML). Similarly, quantification of river outflow to sea also contributes to the large balancing item for the surface water asset. River outflow to sea is based on measured flow data collected at the most downstream station along a river. There is no adjustment made for the contributing area below the gauging station. As such, outflow to sea is likely to be underestimated by 10–20% (+/– 60,000 ML).

The majority of surface water storages within the Adelaide region are used for urban supply to the Adelaide metropolitan area. The inflows and outflows directly into and out of the following surface water storages are reported in Table 4:

• Kangaroo Creek Reservoir
• Little Para Reservoir
• Millbrook Reservoir
• Mount Bold Reservoir
• Myponga Reservoir
• South Para Reservoir
• Warren Reservoir.

All the volumes given in Table 4 relate to water flows into and out of the surface water storages, which are the water assets actively managed in the region, through capture, storage, release and diversion of flows. These flows may be different from the flows reported in the water accounting statements or in Table 2, which refer to flows affecting the surface water store as a whole, including storages, rivers and weirs.

For instance, while runoff reported in Table 2 (line item 9.4) includes all runoff to the surface water store, including to rivers that may not contribute to inflows into the storages, the runoff reported in Table 4 (line item 41.3) includes only river flow or direct landscape runoff into storages. Runoff is calculated using a water balance approach, based on all the other measured or estimated volumes in Table 4, as described in line item 41.3 Runoff into storages.

Table 4. Volume of inflows and outflows for selected surface water storages in the Adelaide region during the 2010–11 year

	Volume (ML)
Opening storage	93,753
41 Storage increases
41.1 Precipitation on storages	10,974
41.3 Runoff into storages	224,458
41.4 Transfer of water into storages	13,685
Total 41 Storage increases	249,117
42 Storage decreases
42.1 Evaporation from storages	15,283
42.5 Releases from storages	59,879
42.6 Diversions from storages	145,256
Total 42 Storage decreases	220,418
Closing storage	120,570
Net change in volume	26,817

The purpose of this note is to provide a consolidated report on the groundwater store within the region during the 2010–11 year. Information on all water flows to and from the groundwater store are presented here, including between store flows and transfers that are not presented in the water accounting statements.

A description of the Adelaide region's groundwater resources is provided in the Groundwater section of the Contextual information.

The value of the groundwater asset was the managed groundwater volume described in the relevant water allocation plans and the carryover balance of managed aquifer recharge credits. The groundwater asset could not be delineated separately by water table aquifer and underlying aquifers; therefore these items were reported as unquantified (dashes in the statements) and the groundwater asset was reported at 2.5 Other groundwater asset.

The groundwater asset did not include the Northern Adelaide Plains, Central Adelaide Plains and Dry Creek Prescribed Wells Areas (see line item 2.5 Other groundwater assets for more information on why these groundwater resources were not quantified).

The closing balance of the groundwater store was marginally lower than the opening balance in the 2010–11 year. Given that the groundwater asset is equivalent to the managed groundwater volume, the volume reported is not expected to vary significantly among years. In general, the managed groundwater volume does not reflect temporal fluctuation of groundwater levels. Therefore, groundwater assets for the region are not responsive to groundwater storage changes resulting from water table fluctuations. As a result groundwater assets are constant except for the carryover balance of managed aquifer recharge credits.

Table 5. Groundwater asset volume at the start and end of the 2010–11 year

	30 June 2011 (ML)	30 June 2010 (ML)
2 Groundwater
2.1 Water table aquifer	–	–
2.2 Underlying aquifers	–	–
2.5 Other groundwater assets	88,252	87,833
Total	88,252	87,833

Groundwater inflows to the groundwater store were substantially greater than groundwater outflows during the 2010–11 year. Volume of inflows and outflows for the groundwater store during the 2010–11 year are given in Table 6. A schematic diagram representing all the inflows and outflows associated with the groundwater store in the Adelaide region is provided in Figure 4.

Figure 4. Schematic diagram of water inflows (blue arrows) and outflows (red arrows) for the groundwater store within the Adelaide region during the 2010–11 year. Solid arrows indicate water transfers; dotted arrows indicate natural water movement; waved arrows indicate leakage. Line item numbers are provided next to the flows.

The most significant contribution to groundwater inflows was recharge from landscape. In the 2010–11 year southeastern Australia experienced above-average rainfall, which is likely to have had a flow on effect to recharge from landscape. By comparison, all other groundwater inflows were minor. Decreases to the groundwater store were balanced across a number of groundwater outflows including discharge to landscape and surface water, and groundwater extractions servicing the various groundwater rights.

Table 6. Volumes of inflows and outflows for the groundwater store during the 2010–11 year

	Volume (ML)
10 Groundwater inflows
10.1 Groundwater inflow from outside region	22
10.2 Groundwater inflow from outside region at coast	2,051
10.3 Recharge from landscape	685,221
10.4 Recharge from surface water	–
10.5 Leakage from off-channel water storage	1,011
10.6 Leakage from urban water system	13,962
10.7 Leakage from irrigation scheme	62
10.8 Managed aquifer recharge - private user	5,455
Total 10 Groundwater inflows	707,784
18 Groundwater outflows
18.1 Groundwater outflow to outside region	390
18.2 Groundwater outflow to outside region at coast	1,363
18.3 Discharge to landscape	99,677
18.4 Discharge to surface water	72,148
18.5 Discharge to off-channel water storage	–
18.7 Extraction - other statutory rights	29,589
18.11 Groundwater allocation extraction	15,019
Total 18 Groundwater outflows	218,186
Balancing item – groundwater store	489,179
Change in groundwater storage	419
Opening groundwater storage	87,833
Closing groundwater storage	88,252

Line items in italic indicate between-store flows. These flows are not presented in the water accounting statements as they occur within the region.

Groundwater extractions in the Adelaide region occur under different types of water rights. These water rights, including entitlements, allocation announcements and forfeiture during the 2010–11 year are provided in the Water rights, entitlements, allocations and restrictions note, in the Groundwater rights table.

Overall the majority of groundwater extractions are used for irrigation but the type of crops irrigated differs by area. The primary use of groundwater extractions, described by groundwater management area and hydrology are provided in the Groundwater section of the Contextual information.

Extractions from the groundwater store under other statutory rights (line item 18.7) accounted for over half (66%) of the total groundwater extraction for the Adelaide region. 

Allocation extractions accounted for 34% of total groundwater extraction during the 2010–11 year and the volume extracted was less than 40% of the total volume allocated.

Figure 5 shows that groundwater extractions have generally decreased in the 2010–11 year compared to 2009–10 year. This may be the result of above-average rainfall experienced during the 2010–11 year reducing demand for groundwater (for further information refer to the Rainfall section of the Contextual information). 

Figure 5. Graph of groundwater extractions from aquifers within the Adelaide region during the 2010–11 year and the 2009–10 year for comparison

This volume represents the volume necessary to reconcile the opening and closing balances of the groundwater store with the physical water inflows and outflows. The Balancing item – groundwater store is calculated according to Table 7.

Table 7. Balancing item for the groundwater store in the 2010–11 year

	Account	Volume (ML)
	Opening balance (30 June 2010)	87,833
add	Total 10 Groundwater inflows	707,784
less	Total 18 Groundwater outflows	218,186
less	Closing balance (30 June 2011)	88,252
	Balancing item – groundwater store	489,179

The calculation of the water balance on the groundwater store yielded a difference of 489,179 ML, approximately 70% of the total groundwater inflows during the 2010–11 year. This value is considerably larger than that reported last year (215,615 ML).

This balance is large but it is not representative of the error made in estimating the groundwater inflows and outflows. It rather reflects the fact that groundwater assets and flows are calculated in ways that do not allow them to reconcile:

• The groundwater asset is quantified as the average long-term groundwater volume available for extraction without adversely impacting the system. This value is essentially constant from year to year.
• Inflows and outflows are estimated by models and represent, albeit with calculation errors, the inflows and outflows that change from year to year, depending on climatic conditions, extractions, etc. Nevertheless, because of the limitations of data availability, there is an inherent limitation in accuracy in the groundwater quantities presented in tables 6 and 7.
• The groundwater asset is only defined for a few of the aquifers of the total aquifers in the Adelaide region.
• The reported recharge from landscape represents potential diffuse recharge to groundwater. This is the amount of water that potentially could reach the water table given the land use and soil type in the region. This volume is not a direct measure of groundwater recharge and does not take into consideration the lag of time that occurs between the rainfall infiltrating into the soil and actually reaching the water table.

Estimated inflows and outflows are more sensibly compared to the change of water stored in the aquifers than to the opening and closing balance of the groundwater asset. As shown in the following section, change in aquifer storage, the large surplus in inflows compared to outflows resulted, during the 2010–11 year, in an increase in groundwater levels and therefore in water stored in the aquifers.

The change in groundwater storage was estimated for the water table aquifer within the sedimentary aquifers of the McLaren Vale Prescribed Wells Area (PWA) and the Adelaide Plains. The change in groundwater levels were estimated using all bores within the water table and using a buffer of 10 km. The results are shown in the Table 8 for the 2010–11 and 2009–10 years.

 Table 8. Changes in aquifer storage estimated for the 2010–11 and 2009–10 years

Management area	Change in storage 2010–11 (ML)	Change in storage 2009–10 (ML)
McLaren Vale PWA water table	3,403	(3,688)
Adelaide Plains water table	45,860	(4,992)
Total	49,263	(8,680)

The increase in aquifer storage for the 2010–11 year shown in Table 9 is consistent with increased groundwater inflows and decreased groundwater outflows. Because the aquifers considered represent only a fraction of the groundwater resources in the Adelaide region, the value in the table only partially reflects the difference between inflows and outflows shown in Table 7. By comparison, aquifer storage decreased during the 2009–10 year, which experienced much lower rainfall and higher abstractions.

Table 9. Change in groundwater storage relative to the groundwater asset

Groundwater management area	ΔS 2009-10 (ML)	ΔS relative to groundwater asset (%)	ΔS 2010-11 (ML)	ΔS relative to groundwater asset (%)
McLaren Vale PWA water table	(3,688)	(52)	3,403	48
Adelaide Plains water table*	(4,992)	–	45,860	–
Total	(8,680)		49,263

ΔS – change in storage

* No change in the groundwater storage relative to groundwater asset has been reported for the Adelaide Plains since resource assessments are in progress for the area and no managed groundwater volume has been defined as an asset.

Data source

South Australian Department for Water: bore locations, groundwater level data and screened aquifer information from online database; Aquaterra 2011.

Method

Change in extractable storage was estimated using a simple geographic information system (GIS) approach based on measured groundwater levels and aquifer properties. Firstly, groundwater levels at the start and end of the 2010–11 year were estimated by interpolating from measurements between March 2010 to October 2010 and March 2011 to October 2011 respectively. 

The estimated groundwater levels on a particular date were then spatially interpolated to grids using the ArcGIS Topo-to-Raster tool. The interpolated groundwater-level surfaces at the start and the end of financial year were then used to calculate the volume between them within the sedimentary area. For comparison, the change in groundwater level at the start and the end of the year at each bore was also used to interpolate a change in groundwater level surface. Finally, these volumes were multiplied by appropriate specific yield values to convert to a change in groundwater storage. The two estimates were compared for consistency and the average of these volumes was reported for the unconfined aquifers only.

In agreement with the Adelaide Plains groundwater model report it is assumed that evaluated observation bores represent an area of about 10 km². There average of the results from the two methodologies was then reported as the change in storage for the selected areas.

Figure 6. Map of Adelaide buffer zone change in storage 

Assumptions, limitations, caveats and approximations

Change in groundwater storage was not calculated for confined aquifers. The annual change in storage was considered to be negligible for confined aquifers due to their very low storativity, which is much lower than the specific yield of unconfined aquifers (Freeze and Cherry 1979; Johnson 1967). Upon lowering of water levels in such aquifers, they remain fully saturated so that no dewatering occurs. The water diverted is volumetrically equivalent to the volumetric expansion of the water and contraction of the pore space.

Outside the 10-km buffer zone, where no groundwater level measurements are available, the change in storage is considered zero. This is due to the inability of estimating any change because of lack of data.

Annual change in storage in fractured bedrock was considered negligible as the fractures are the only water-holding structures and these systems have a low specific yield. Furthermore, groundwater extraction in fractured rock areas is limited in volume. On an annual basis, it is assumed that any increase or decrease in rainfall is counterbalanced by an increase or decrease in evapotranspiration and in discharge to rivers through baseflow.

A constant specific yield of 0.01 was used in agreement with the Adelaide Plains groundwater model report (Aquaterra 2011).

Uncertainty

The uncertainty in the field-measured data (e.g. groundwater levels, specific yield) was not specified and hence the impacts of such uncertainty on the change in storage is not estimated. The change in storage estimations were based on interpolated groundwater-level grids produced using the ArcGIS Topo-to-Raster tool. Use of other interpolation methods may impact the values of the groundwater-level grids and hence the estimated values for change in groundwater storage.

This note reports on the urban water system and its interactions with the Adelaide region's surface water, groundwater and irrigation schemes, as well as its interactions with systems outside of the Adelaide region, such as the River Murray.

The Sub-systems analysis note analyses the urban system at a finer level, splitting it into sub-systems (supply, wastewater and recycled water).

Background information on the urban water system within the Adelaide region is in the Other water resources and urban system section of the Contextual information. The extent of the urban water supply and collection systems within the Adelaide region can be seen in the Figure P6 of the Contextual information.

The volume of the urban water system store includes water held in pipes that were part of the potable, wastewater and recycled pipe network, as well as tanks and urban storages. Urban water storages were categorised based on their location (off the river channel), the fact that they had diversion channels around the perimeter, preventing capture of runoff and they were used soley to supply their respective water treatment plants.

Urban storages made up the majority (90%) of the urban water system store and included: Barossa Reservoir, Happy Valley Reservoir, Hope Valley Reservoir and Onkaparinga Summit Storage. The urban water system excluded water held in wastewater treatment lagoons as these volumes could not be quantified in a way that is complete, neutral and free from material error due to a lack of available data. Therefore the volume reported for the urban water store is an underestimate of the total water asset.

Table 10. Urban water system store volume at the start and end of the 2010–11 year

3 Urban water system	30 June 2011 (ML)	30 June 2010 (ML)
3.1 Urban water supply system	18,218	18,205
3.2 Wastewater collection system	95	95
3.3 Recycled water supply system	10	10
3.4 Urban inter-region claim	0	0
Total 3 Urban water system	18,323	18,310

There was only a marginal increase in storage volume for the urban water store in the 2010–11 year (Table 10). New pipe construction was minimal across the potable, wastewater and recycled pipes network during 2010–2011. This was reflected by a slight increase (1 ML) in the volume of water store in SA Water's urban water system pipe network within the Adelaide region. However, for wastewater and recycled water pipe construction, only a very small (<1 ML) increase was recorded such that comparisons between the opening and closing balance for these items showed no change between 2010 and 2011 due to rounding of volumes. It should be noted that the urban water system pipe network (including recycled and wastewater) extends beyond the boundary of the Adelaide region and changes in pipe capacities are not a reflection of changes occurring outside the Adelaide region. Urban water storages have diversion channels around the perimeter of the storages, which prevents the capture of runoff; therefore significant increases in urban water storage volumes were not expected.

Figure 7. Location map of urban water storages within the Adelaide region. The percentage full volume on 30 June 2011 for each storage is also shown.

A schematic diagram representing all the inflows and outflows associated with the urban water system in the Adelaide region is provided in Figure 8. The inflow and outflow volumes for the urban water system during the 2010–11 year are given in Table 11.


Figure 8. Schematic diagram of water inflows (blue arrows) and outflows (red arrows) for the urban water store within the Adelaide region during the 2010–11 year. Solid arrows indicate water transfers; dotted arrows indicate natural water movement; waved arrows indicate leakage. Line item numbers are provided next to the flows.

Table 11. Volume of inflows and outflows for the urban water system store during the 2010–11 year

11 Urban water system inflows	Volume (ML)
11.1 Precipitation on urban water system	2,052
11.2 Non-allocated diversion of surface water	120,014
11.4 Wastewater collected	92,024
11.9 Delivery of water to urban water sytstem under inter-region agreement	45,346
Total 11 Urban water system inflows	259,436
19 Urban water system outflows
19.1 Evaporation from urban water	3,289
19.3 Leakage to groundwater	13,962
19.4 Delivery to urban water users	125,686
19.5 Urban water discharge to surface water	2,425
19.6 Urban water discharge to irrigation scheme	15,977
19.7 Wastewater discharge outside of region	70,836
19.11 Transfer of water outside of region	3,476
19.20 Other urban water decreases	7,747
Total 19 Urban water system outflows	243,398
Balancing item – urban water system	16,025
Change in urban water system storage	13
Opening urban water system storage	18,310
Closing urban water system storage	18,323

Line items in italic indicate between-store flows. These flows are not presented in the water accounting statements as they occur within the region.

In the Adelaide region water for urban supply comes from two main sources:

• water harvested from the Mount Lofty Ranges catchments within the Adelaide region
• River Murray water imported via the Mannum–Adelaide and Murray Bridge–Onkaparinga pipelines.

Water harvested from the Adelaide region's catchments provided the majority of water supplying the urban water supply system during the 2010–11 year (72% of source water). Imported River Murray water constituted approximately 28% of the urban water supply system's source water. Similar proportions of water sources were observed during 2009–10; however the total volume required for urban water supply was marginally less (6% less) in the 2010–11 year.

River Murray water imported via the Mannum–Adelaide, Murray Bridge–Onkaparinga and Swan Reach–Stockwell pipelines occurs via a Class 6 water access entitlement to shares in the River Murray consumptive pool for South Australia. This entitlement is intended specifically for reticulated public water supply to metropolitan Adelaide and diversions are reported at 11.9 Delivery of water to urban system under inter-region claim. This water source supplements Adelaide's urban water supply system. The volume diverted in any given year will vary depending on prevailing climatic conditions because:

• rainfall and subsequently stream flows within the River Murray Catchment will determine the volume of water available to be taken, advised via allocation announcements
• rainfall within the Adelaide region's catchments will determine the demand on the River Murray water to supplement the Adelaide region's urban water supply system.

Figure 9 summarises the volumes received by the urban water supply system from these sources in the 2010–11 year and, for comparison, the 2009–10 year. 

Figure 9. Graph of sources of water for Adelaide's urban water system

Most of the treated wastewater from the urban wastewater collection system is discharged into the sea (line item 19.7) accounting for approximately 97% of wastewater discharged in the Adelaide region. A small portion (3%) of wastewater is treated and subsequently discharged to surface water (line item 19.5).

This volume represents the volume necessary to reconcile the opening and closing balances of the urban water system store with the physical inflows and outflows. The balancing item – urban system is calculated according to Table 12.

Table 12. Balancing item for the urban water system for the 2010–11 year

	Account	Volume (ML)
	Opening balance (30 June 2010)	18,310
add	Total 11 Urban water system inflows	259,436
less	Total 19 Urban water system outflows	243,398
less	Closing balance (30 June 2011)	18,323
	Balancing item – urban water system	16,025

The balancing item is based on a fine analysis of the urban sub-systems (see the Sub-systems anlaysis note). The balancing item for water flows into and out of the urban water store was 16,025 ML, approximately 5.5% of the total urban inflow. This is due to a combination of meter errors, data measurement and handling errors, calculation and estimation errors (leakage, precipitation and evaporation), and from unreportable flows such as stormwater infiltration and groundwater infiltration.

In times of severe water shortages SA Water can implement a regime of water conservation or restriction measures on behalf of the South Australian Minister for Water. As of 1 December 2010, Level 3 enhanced restrictions were removed and Water Wise Measures introduced. South Australia does not have a defined set of water restriction levels; specific levels and conditions are announced as the need arises.

The urban water system is made up of three sub-systems, which serve the urban water users: the urban water supply system, the wastewater collection system and the recycled water system. The main urban water users are residential, commercial, industrial and municipal consumers.

This note complements the System's interactions with the region note. It gives the following additional information:

• split of the urban water flows according to the sub-systems they affect
• flows between sub-systems, which are not reported in the System's interactions with the region note because they occur within the whole urban water system
• split of the total urban water use into several components.

The urban water supply system collects water from various sources including surface water and transfers-in across the region's geographical boundaries. It treats and distributes water to urban water users. Part of the water is used outdoor (e.g. garden use) while the rest is collected into the wastewater collection system. Wastewater is treated and then discharged to surface water, the sea or the landscape, or delivered into the recycled water system. The recycled water system, in turn, distributes treated water to users.

Tables 13 to 15 show the balance of each sub-system including its inflows, outflows, balancing item and percentage error of the balancing item compared to the total of the inflows. The balancing items are calculated as the difference between the inflows less the outflows, considering that the changes in storage are not material. The values of the balancing items reflect measurement and data handling errors and/or missing data.

Table 16 shows a breakdown of the total urban water use per use sectors and type of water (potable, non-potable and recycled).

For each row in the tables 13 to 15, correspondence is given to the line items that are reported in the Water accounting statements and the System's interactions with the region note. The correspondence can be:

• Line item A: meaning a one-to-one correspondence of the volume in the table with the line item A.
• Part of line item A: meaning that the volume in the table is a part of the line item A.
• Line item A + line item B: meaning that the volume in the table is the sum of line items A and B.
• Part of line item A + line item B: meaning that the volume in the table is the sum of a part of line items A and a part of line item B.
• Not applicable: in the case when there is no correspondence to a line item.

When a volume in a table is given as '0' it means that the value has been evaluated as nil for the 2010–11 year. When the volume in a table is given as a dash (–), it means that the volumes could not be quantified for the 2010–11 year.

Supporting information and quantifications approaches for each volume shown in the tables 13 to 16 can be accessed via links on the line item numbers. In the cases when there is no corresponding line item, the supporting information and quantification approaches are given at the end of the note.

Table 13. Balance of the urban water supply system in the 2010–11 year

Flow component	Volume (ML)	Line item
Inflow component:
Precipitation on urban water system	2,052	11.1
Surface water diverted	120,014	11.2
Total potable water imported	3,083	Potable water component of 11.9
Total non-potable water imported	42,263	Non-potable water component of 11.9
Total inflow	167,412
Outflow component:
Evaporation from urban water system	3,289	19.1
Potable water supplied to water users	123,102	Potable water component of 19.4 (see table 16)
Potable water exported	3,476	19.11
Water treatment plant (WTP) losses	6,596	WTP loss component of 19.20
Water lost due to leakage	13,789	Water mains leakage component of 19.3
Total outflow	150,252
Balance (inflows less outflows)	17,160
Error	10.25%

The balancing item is attributed to meter errors, data handling errors, modelling errors and missing items, such as urban water storage releases and other unreported losses. A significant rainfall event in August and September 2011 led to a release from the Happy Valley Reservoir; however, the volume of this release was not available. Other losses from the storages include groundwater losses and seepage.

Table 14. Balance of wastewater collection system for the 2010–11 year

Flow component	Volume (ML)	Line item
Inflow component:
Wastewater inflow into wastewater treatment plants	92,024	11.4
Ingress of stormwater and groundwater	–
Recycled water used on-site in-process	1,453	Not applicable: reporting and quantification approach given below
Total inflow	93,477
Outflow component:
Wastewater (treated) discharged to surface water	2,425	Wastewater component of part of 19.5
Wastewater (treated) discharged to sea	70,836	19.7
Sub-total – treated wastewater discharged	73,261
Overflow to stormwater and groundwater	–
Wastewater treatment process losses	1,151	Wastewater component of 19.20
Treated wastewater supplied as recycled water	20,082	Not applicable: reporting and quantification approach given below
Total outflow	94,494
Balance (inflows less outflows)	(1,017)
Error	(1.09)%

Misbalance is due to meter errors, data handling errors, estimation errors from databases, and missing items or temporal values.

Table 15. Balance of the recycled water system for the 2010–11 year

Flow component	Volume (ML)	Line item
Inflow component:
Recycled water produced at wastewater treatement plant	20,082	Not applicable: reporting and quantification approach given below
Total inflow	20,082
Outflow component:
Recycled water used on-site in-process	1,453	Not applicable: reporting and quantification approach given below
Recycled water used on-site for outdoor irrigation	68	Not applicable: reporting and quantification approach given below
Sub-total – recycled water used on-site	1,521
Water lost due to leakage	173	Recycled water leakage component of 19.3
Supply to irrigation schemes	15,977	19.6
Total recycled water supplied to urban users	2,584	Recycled water component of 19.4 (see Table 16)
Total outflow	20,255
Balance (inflows less outflows)	(173)
Error	(0.86)%

Table 16. Urban water consumption for the 2010–11 year

	Potable		Recycled		Total (ML)
	Volume (ML)	Line item	Volume (ML)	Line item
Residential	82,915	Part of 19.4	10	Part of 19.4	82,925
Commercial, industrial and municipal uses	24,590	Part of 19.4	2,362	19.4	26,952
Other uses:
Agricultural/individual irrigation	3,142	Part of 19.4	212	Part of 19.4	3,354
Other	12,455	Part of 19.4			12,455
Sub-total – other uses	15,597	Part of 19.4	212	Part of 19.4	15,809
Total volume supplied	123,102		2,584		125,686

Figure 10 represents the inflows and outflows reported in tables 13 to 16 that occur between and within urban sub-systems and between urban systems and urban users. Flows that occur in the urban water system but could not be quantified are faded out.

Figure 10. Schematic diagram of water inflows and outflows for the urban sub-systems. Flow volumes and the corresponding line item numbers are provided next to the arrows and are shown in [ ] or with reference to the appropriate table number. Faded out arrows indicate water flows that could not be quantified.

There are four unquantified inflow and outflow components in Figure 10. Insufficient data were available to quantify these volumes however they are important components of the urban water balance.

Individually abstracted water includes water abstracted from surface water, groundwater or rainwater by individual users. That is, water diverted from a stream, pumped from a domestic garden bore or sourced from a rainwater harvesting system.

The unquantified stormwater component represents stormwater that is claimed and then used by urban water consumers such as that which is collected, treated and used in municipal stormwater schemes or projects.

The outflow of water to Landscape/outdoor represents the unquantified volume of water that urban users apply or discharge to the landscape. This includes garden, park and sports field watering, car washing and paved surface cleaning.

The unquantified line item [11.7] indicates groundwater or stormwater ingress into the stormwater system.

The following notes are provided for the volumes in tables 13 to 16 and Figure 10 that do not correspond to any line item in the water accounting statements or the System's interactions with the region note.

Volume: 20,082 ML

The 2010–11 year volume of recycled water produced was supplied from WWTPs operated by SA Water. The volume represents metered outflows that are manually read and recorded by plant operators.

Data source

SA Water: WWTP records.

Data provider

SA Water.

Method

The following table below lists the volume of recycled water produced by WWTPs in the 2010–11 year for residential, commercial, industrial and municipal use.

Volume of recycled water produced by WWTPs in the 2010–11 year

Wastewater treatment plant	Discharge (ML)
Aldinga	150
Angaston	27
Bird-in-Hand	68
Bolivar	15,951
Christies Beach	1,755
Glenelg	1,945
Gumeracha	54
Hahndorf	1
Myponga	35
Victor Harbor	96
Total	20,082

Assumptions, approximations, caveats and limitations

This line item does not include any community waste management schemes (CWMSs) managed by local councils.

Uncertainty

The uncertainty estimate was not quantified.

Volume: 1,453 ML

This volume represents the volume of recycled water used on-site in-process at the Bolivar  and Christies Beach WWTP during the 2010–11 year.

Data source

SA Water: WWTP records.

Data provider

SA Water.

Method

The recycled water used on-site or in-process during the 2010–11 year was obtained from SA Water WWTP flow meter records.

Recycled water used on-site or in-process in the 2010–11 year

Wastewater treatment plant	Re-use	Volume (ML)
Christies Beach	Recycled water used in-process	163
Bolivar	Recycled water used in-process	1,290
Total		1,453

Assumptions, approximations, caveats and limitations

Nil.

Uncertainty

The uncertainty estimate was not quantified.

Volume: 68 ML

This volume represents the volume of recycled water used on-site in-process at the Bird‑in‑Hand WWTP during the 2010–11 year. The 2009–10 year on-site in-process use is also given for comparison.

Recycled water used on site

Wastewater treatment plant	Re-use	2009–10 volume (ML)	2010–11 volume (ML)
Bird-in-Hand	Outdoor use	139	68

Data Source

SA Water: WWTP records.

Data Provider

SA Water.

Method

The recycled water used on-site or in-process during the 2010–11 year was obtained from SA Water WWTP flow meter records.

Assumptions, approximations, caveats and limitations

Nil.

Uncertainty

The uncertainty estimate was not quantified.

The purpose of this note is to provide a consolidated report on the irrigation schemes within the region during the 2010–11 year. Information on all water flows to and from the irrigation schemes is presented here, including between store flows and transfers that are not presented in the Water accounting statements.

Three major irrigation schemes operate in the Adelaide region: Barossa Infrastructure Limited, Virginia Pipeline Scheme and Willunga Water Basin Company.

Background information on these irrigation schemes in the Adelaide region can be found in the Other water resources and distribution systems section of the Contextual information.

The volume of water in the irrigation schemes was 29 ML (see line item 4.1 Irrigation water supply system). This volume did not change during the 2010–11 year.

The inflow and outflow volumes for the irrigation schemes during the 2010–11 year are given in Table 17.

Table 17. Volumes of inflows and outflows for the irrigation schemes during the 2010–11 year

	Volume (ML)
12 Irrigation schemes inflows
12.1 Precipitation on irrigation scheme	–
12.4 Urban water discharge to irrigation scheme	15,977
12.6 Delivery of water to irrigation scheme under inter-region agreement	2,301
12.18 Other irrigation water increases	253
Total 12 Irrigation schemes inflows	18,531
20 Irrigation schemes outflows
20.1 Evaporation from irrigation scheme	–
20.3 Leakage to groundwater	62
20.4 Delivery to irrigation scheme users	14,789
Total 20 Irrigation schemes outflows	14,851
Balancing item – irrigation schemes	3,680
Change in irrigation schemes storage	0
Opening irrigation schemes storage	29
Closing irrigation schemes storage	29

Line items in italics indicate between-store flows. These flows are not presented in the water accounting statements as they occur within the region.

This volume represents the difference between the measured opening and closing balances of the irrigation schemes, after physical inflows and outflows have been applied (see Table 18).

Table 18. Balancing item for the irrigation scheme for the 2010–11 year

	Account	Volume (ML)
	Opening balance (30 June 2010)	29
add	Total 12 Irrigation schemes inflows (see Table 2)	18,531
less	Total 20 Irrigation schemes outflows (see Table 2)	14,851
less	Closing balance (30 June 2011)	29
	Balancing item – irrigation scheme	3,680

The calculation of the water balance on irrigation schemes yielded a balancing item of 3,680 ML. This is a significant portion (20%) of the total irrigation schemes inflows during the 2010–11 year.

The large balancing item may be due to:

• Different methods of measuring flows to and from the irrigation scheme for different data suppliers. The inflow of recycled water to the Virginia Pipeline Scheme was provided from SA Water wastewater records, whereas the outflow from the Virginia Pipeline Scheme was the metered volume at the Virginia Pipeline Scheme pump station. The difference between these two volumes is significant and may be due to meter errors at either end of the flow and unquantified losses between supply from SA Water to Virginia Pipeline Scheme and supply to Virginia Pipeline Scheme customers.
• Unquantified line items. The fact that evaporation and precipitation were not quantified is not expected to have had a material impact on the balancing item reported.
• Inconsistent time periods for measurement. The irrigation year is September to September and customer meters are not read on 30 June 2011. Therefore, the volume reported for delivery to irrigation scheme users for the Virginia Pipeline Scheme was the metered volume of water at their pumping station, not at customer meters.

The purpose of this note is to report on water held in off-channel water storages within the Adelaide region during the 2010–11 year. Where available, water flows to and from off-channel water storages are reported here. Water held in off-channel water storages is not reported in the Water accounting statements because the statements report only on water resources yet to be shared. Water held in off-channel water storages is considered to be abstracted from the shared pool of water resources and, as such, is not included as part of the region (for more information refer to the General description of the Contextual information).

This note provides additional information about the water assets and water liabilities recognised in the Water accounting statements. This note reports on water that has been harvested from the landscape into off-channel water storages and thus did not contribute to groundwater recharge or runoff into surface water .

A description of the Adelaide region's off-channel water resources is provided in the Other water resources and distribution systems section of the Contextual information.

The volume of water held in off-channel water storages (27.1 Off-channel water storages) increased from 10,360 ML at the beginning of the 2010–11 year by almost 50% to 15,158 ML at the end of the 2010–11 year. This increase in off-channel water storage is attributed to the increased inflows into the storages during the 2010–11 year, driven by above-average rainfall experienced throughout the year (refer to the Rainfall section of the Contextual information).

The volume of water reported for off-channel water storages included only storages filled primarily by rainfall-runoff harvesting. Volumes of water held in off-channel water storages filled by groundwater extractions, surface water diversions or recycled water were excluded as these volumes could not be quantified in a way that is complete, neutral and free from material error, due to a lack of available data. However, it is expected that this volume is not material as these types of off-channel water storages only make up a small proportion of off-channel water storage capacity within the Adelaide region.

The volumes reported in Table 19 do not include flows to or from rainwater tanks. The majority of volumes reported for inflows and outflows to off-channel water storages were modelled (see individual item quantification approaches), with the exception of a small portion of water use (31.3 Water use). Data were unavailable for inflows to off-channel water storages via surface water diversions and groundwater extractions. Thus, the only volumes reported for inflows to off-channel water storages were runoff harvesting and precipitation, both of which made a significant contribution to the overall inflow to off-channel water storages in the 2010–11 year.

Evaporation from off-channel water storages was the most significant outflow from off-channel water storages, more than twice the volume reported for water use and almost equal to inflows from runoff harvesting.

While the volume reported for water use was mainly derived from modelled data, a small portion of this volume was actually measured data (31.3 Water use) for the Barossa Prescribed Water Resources Area.

Table 19. Inflows and outflows for the off-channel water store in the Adelaide region during the 2010–11 year

	Volume (ML)
30 Off-channel water inflows
30.1 Precipitation on off-channel water store	13,768
30.2 Groundwater discharge into off-channel water store	–
30.3 Runoff harvesting into off-channel water store	18,643
30.4 Surface water diversion into off-channel water store	–
30.5 Groundwater extraction into off-channel water store	–
Total 30 Off-channel water inflows	32,411
31 Off-channel water outflows
31.1 Evaporation from off-channel water storages	18,639
31.2 Leakages from off-channel water storages	1,011
31.3 Water use	7,970
Total 31 Off-channel water outflows	27,620
Balancing item – off-channel water store	(7)
Change in off-channel water storage	4,798
Opening off-channel water storage	10,360
Closing off-channel water storage	15,158

This volume represents the volume necessary to reconcile the opening and closing balances of the off-channel water storage with the physical water inflows and outflows. The difference was calculated according to Table 20.

Table 20. Balancing item for the off-channel water store for the 2010–11 year

	Account	Volume (ML)
	Opening balance (30 June 2010)	10,360
add	Total 30 Off-channel water inflows (see Table 1)	32,411
less	Total 31 Off-channel water outflows (see Table 1)	27,620
less	Closing balance (30 June 2011)	15,158
	Balancing item – off-channel water store	(7)

The calculation of the water balance on the off-channel water storages yielded a negative balance of 7 ML. Although a large balancing item was not observed for the off-channel water store, it should be noted that volumes reported were mainly derived from modelled data. The modelling process essentially constrains the data to achieve a water balance, hence removing any potential balancing difference.