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National Water Account 2016

Adelaide: Water stores

These notes provide a water balance for each of the region's water stores for the 2015–16 year. Below-average rainfall conditions have continued in the region over several years, and this has negatively impacted surface water runoff and aquifer recharge. Despite a decline in natural inflows into storages, surface water storage volumes in the Adelaide region increased slightly during the 2015–16 year due to water transfers from the River Murray. Groundwater extraction increased slightly during the year, as dry conditions put pressure on water resources.

 

Figure depicting key messages for the Adelaide region 

Surface water store

Gawler Caravan Park (© Bureau of Meteorology SA Office)

 

The volume of water in the Adelaide region's surface water store increased marginally during the 2015–16 year from 94,769 ML at 1 July 2015 to 103,300 ML at 30 June 2016 (Table S5).

 

Table S5 Water balance for the surface water store
  2016
ML
2015
ML
Opening surface water store 94,769 122,502
Inflows 391,805 382,364
Outflows (238,803) (263,035)
Balancing item (144,471) (114,118)
Closing surface water store  103,300 94,769

 

A schematic diagram representing all surface water inflows and outflows during the 2015–16 year is provided in Figure S4.

 

Figure S4 Water inflows and outflows for the surface water store during the 2015–16 year

Figure S4 Water inflows and outflows for the surface water store during the 2015–16 year

 

Surface water inflows

Although higher rainfall was experienced across the region compared to 2014–15, total rainfall during the year was still below average. Precipitation on storages increased marginally compared with the previous year; however, the largest natural water inflow in the region, runoff, was approximately 29% less than the previous year.  The combined effects of poor rainfall and soil moisture conditions experienced for successive years (see Climate and water) meant that the increase in rainfall observed in 2015–16 did not translate to an overall increase in runoff and inflows to storages. 

Discharge: groundwater remained the same as the previous year. This volume includes annual baseflow from groundwater to watercourses within the Western Mount Lofty Ranges Prescribed Water Resources Area and baseflow measured at the Yaldara gauging station on the North Para River.

Delivery: inter-region in 2015–16 was 140,144 ML, more than double the 63,827 ML that was delivered from the River Murray in the previous year. SA Water imports water into the region for urban water supply (see Water supply inflows); this water is received into several storages in the region and is available for transfer to the urban water system (see Surface water outflows).

Surface water outflows

The largest natural water outflow is river outflow from the region, which decreased by 34% from the previous year. This decrease in river outflow corresponds with the lower runoff volumes reported for the 2015–16 year due to the ongoing dry conditions in the region (see Climate and water). Evaporation decreased by 36%. This may be attributed to surface water storage volumes being low throughout most of the year thereby providing less surface area for evaporation. 

SA Water diverted a total of 149,118 ML from surface water storages to the Adelaide metropolitan area for urban water supply. Around 14% of urban water diverted from surface water storages was sourced from the Western Mount Lofty Ranges Prescribed Water Resources Area as an allocated diversion: urban system; this is a 73% decrease in volume diverted under this entitlement compared to 2014–15. The remaining volume (approximately 84%) was diverted into the urban water system as a non-allocated diversion: urban system; this water was originally imported into the region from the River Murray and represents an increase of more than twice the volume of River Murray water sourced in the previous year. By obtaining water from the River Murray, SA Water was able to alleviate the reliance on surface water storages which had been impacted by several years of below average rainfall.

Allocated diversion: individual users was 3,970 ML and represents the water diverted for non-urban purposes in Western Mount Lofty Ranges and Barossa prescribed water resources areas (PWRAs). Volumes allocated and diverted on a PWRA basis are shown in Figure S5.

 

Figure S5 Surface water diversions for the Adelaide region during the 2015–16 year; percentage of allocation diverted is also shown
Figure S5 Surface water diversions for the Adelaide region during the 2015–16 year; percentage of allocation diverted is also shown

 

For a more detailed description of the water usage in the region, and the associated entitlements, see the Surface water rights note.

Surface water balancing item

The surface water balance (Table S5) required a balancing item of 144,471 ML. Inflows to the region were 60% higher than reported outflows. 

The balancing item is primarily attributed to the fact that river and floodplain losses cannot be quantified in the account. It is likely that these losses are a relatively large source of surface water decrease throughout the region. It is also likely that a portion of the balancing item is attributed to uncertainties associated with the runoff estimation (a large source of surface water increase). Runoff is estimated from a rainfall–runoff model (see Methods), and it is reasonable to expect a relatively high uncertainty around this volume.

 

Groundwater store

Artesian Bore, South Australia (iStock © John Carnemolla)

 

The volume of water in the Adelaide region's groundwater store is assumed to remain unchanged throughout the 2015–16 year (Table S6). The groundwater asset in the Adelaide region is equivalent to the managed groundwater volume reported in relevant water allocation plans and does not reflect fluctuation of groundwater levels over time.

 

Table S6 Water balance for the groundwater store
  2016
ML
2015
ML
Opening groundwater store 86,356 86,356
Inflows 121,144 432,444
Outflows (132,689) (461,859)
Balancing item 11,545 29,415
Closing groundwater store 86,356 86,356

 

A schematic diagram representing all groundwater inflows and outflows during the 2015–16 year is provided in Figure S6.

 

Figure S6 Water inflows and outflows for the groundwater store during the 2015–16 year

Figure S6 Water inflows and outflows for the groundwater store during the 2015–16 year

 

Groundwater inflows

The largest natural water inflow in the region is recharge: landscape, which makes up almost 81% of the total groundwater inflows. Due to the Adelaide region's ongoing dry condition, recharge decreased by more than 75% from the previous year (see Climate and water). Inter-region flow and inter-region coastal flow are very small volumes in terms of natural inflows; both these volumes change little from year to year.

Leakage: urban system during the 2015–16 year was slightly less than the previous year. Managed aquifer recharge: urban water system increased by 35% from last year to 324 ML; this volume is later supplied to the irrigation system (see Groundwater outflows). In addition to the aquifer recharge supplied via the urban water system, harvested stormwater volume for several licences is reported as managed aquifer recharge: individual users. This was a similar volume to that reported in the previous year.

Groundwater outflows

The largest natural water outflow in the region is discharge: surface water, making up 56% of all groundwater outflows. This volume represents annual average baseflow and changes little from year to year. Discharge: landscape was not quantified for the 2015–16 year due to lack of available data, although it made up 73% of groundwater outflows in 2014–15.

All allocated extractions reported for the Adelaide region are for individual users; the urban water system does not access groundwater in the Adelaide region. Allocated extraction: individual users increased by 11% from the previous year, reflecting the need to access a higher volume of water during periods of low rainfall. The volume extracted from each management area is shown in Figure S7. Non-licensed groundwater extractions did not change from the previous year and were reported as extraction: statutory rights.

The volume of water supplied as non-allocated extraction: irrigation is similar to the volume reported in groundwater inflows as managed aquifer recharge to the urban system. This water is directly recovered from the Aldinga Aquifer Storage Recovery Scheme and the volume increased by 35% from the previous year. 

For a more detailed description of the water usage in the region and the associated entitlements, see the Groundwater rights note.

 

Figure S7 Groundwater extractions for the Adelaide region during the 2015–16 year; percentage of allocation diverted is also shown
Figure S7 Groundwater extractions for the Adelaide region during the 2015–16 year; percentage of allocation diverted is also shown

 

Groundwater balancing item

The groundwater balance (Table S6) required a balancing item of 11,545 ML, less than 1% of the total groundwater inflows during the 2015–16 year. This volume actually represents the net change in groundwater store throughout the year.

The volume reported as the balancing item for the groundwater store is the difference between total inflows and total outflows because the groundwater asset in the Adelaide region is equivalent to the managed groundwater volume reported in relevant water allocation plans. It does not reflect fluctuation of groundwater levels over time. Therefore, estimated inflows and outflows were compared to the change of water stored in the aquifers to ascertain whether the change in the storage reflected the balancing item (inflow–outflow difference). The change in aquifer storage was calculated using groundwater levels for McLaren Vale, Adelaide Plains, and fractured rock areas within the region. The decrease in storage was estimated as –45,120 ML. Recharge: landscape was approximately 300,000 ML less than that reported for the previous year and discharge: landscape was not reported in the 2015–16 year. It is assumed that the net change in groundwater storage during the 2015–16 year was mainly due to low recharge from the landscape (see Climate and water).

 

Urban water

City of Adelaide, Torrens River, South Australia (iStock © Ben Goode)

 

The volume of water in the Adelaide region's urban water system was assumed to remain unchanged throughout the year (Table S7).

 

Table S7 Water balance for the urban water system
  2016
ML
2015
ML
Opening urban water store
Inflows 250,878 249,330
Outflows (252,441) (243,692)
Balancing item 1,563 (5,638)
Closing urban water store

 

A schematic diagram representing all urban inflows and outflows during the 2015–16 year is provided in Figure S8.

Figure S8 Water inflows and outflows for the urban water store during the 2015–16 year

Figure S8 Water inflows and outflows for the urban water store during the 2015–16 year

 

A more detailed breakdown of the inflows and outflows of the urban water system components is provided in the urban water balance diagram.

Water supply inflows

Total net inflow to the water supply system was 156,804 ML, which is similar to the volumes reported for the previous four years (Figure S9).

Figure S9 Water sources used in Adelaide's urban supply system during the 2015–16 year compared with the previous five years
Figure S9 Water sources used in Adelaide's urban supply system during the 2015–16 year compared with the previous five years
 

 

Inter-region inflow from the River Murray comprised 82% of the water transferred to the urban water system in 2015–16. Water that is imported into the region from the River Murray is placed in storages (see Surface water store) and diverted to the urban water system as a non-allocated diversion: urban water system. SA Water also sources water from the Western Mount Lofty Ranges PWRA as allocated diversion: surface water. This is less than one third of the water sourced from Western Mount Lofty Ranges storages in the previous year, and the smallest volume sourced in the past six years. 

Similarly, the volume of water sourced as delivery: desalinated water was the smallest volume since the Adelaide desalination plant was commissioned and decreased by 66% from the previous year. Testing of the plant was initially conducted after the plant's commissioning and involved increasing plant output over the first few years. With testing over, output from the desalination plant has been scaled back to meet minimum maintenance requirements.

Wastewater and recycled water inflows

Total wastewater collected and delivered to wastewater treatment plants within the Adelaide region's urban water system were 95,637 ML during the 2015–16 year. This was very similar to the volume that was collected the previous year.

Water supply outflows

Total outflows from the water supply system were 156,803 ML and comprised the following (Figure S10):

Figure S10 Outflows from the water supply system
Figure S10 Outflows from the water supply system

 

Supply system delivery: urban users is the major urban water supply system outflow, and the volume changed very little compared with the previous year; however, a notable increase (more than double) in the volume of water exported from the region was observed, as reported against supply system transfer: inter-region.

Approximately 11% of the total outflow from the urban supply system was related to losses (Figure S10). Losses include leakage: groundwater and other supply system losses and were 10% less than those reported in the previous year.

Wastewater and recycled water system outflows

Total outflows from the wastewater and recycled water system  were 94,075 ML and comprised the following (Figure S11):

 

Figure S11 Outflows from the wastewater and recycled water systems
Figure S11 Outflows from the wastewater and recycled water systems

 

Over half of the reported wastewater and recycled system outflows were discharge: sea. Approximately 28% of all outflows were recycled, including recycled water delivery: irrigation and recycled water delivery: urban users. Of the 21,194 ML delivered to the irrigation system, 16,374 ML was delivered to the Virginia Pipeline Scheme and 4,820 ML was delivered to Willunga Basin Water Company.

Managed aquifer recharge comprised less than 1% of all wastewater and recycled water outflows, and is slightly higher than the 210 ML reported in 2014–15. Other wastewater decreases primarily refers to evaporation losses from wastewater treatment lagoons and was 12% higher than those reported in the previous year.

Recirculation of treated wastewater and recycled water that occurs in the system may be subjected to additional treatment and/or re-use on site. The reported urban system outflows exclude any such recirculated volumes in the system.

Urban water system balancing item

The urban water balance (Table S7) required a small balancing item of 1,563 ML. This is less than 0.1% of the total urban water system inflows during the year. The misbalance may be due to a number of factors, such as metering inaccuracies, unaccounted losses, and inaccuracies in the estimation of certain volumes.

 

Irrigation scheme

Irrigated vineyard, South Australia (iStock © moisseyev)

 

The Adelaide region's irrigation scheme is represented by three individual systems: Barossa Infrastructure Limited, Willunga Basin Water Company, and the Virginia Pipeline Scheme. The volume of water in the irrigation scheme is assumed to remain unchanged throughout the year (Table S8).

 

Table S8 Water balance for the irrigation scheme
  2016
ML
2015
ML
Opening irrigation scheme store  –
Inflows  30,881  29,101
Outflows  28,815  26,992
Balancing item  2,066  2,109
Closing irrigation scheme store

 

A schematic diagram representing all irrigation inflows and outflows during the 2015–16 year is provided in Figure S11.

 

Figure S11 Water inflows and outflows for the irrigation scheme during the 2015–16 year
Figure S11 Water inflows and outflows for the irrigation scheme during the 2015–16 year

 

Around 69% of the inflows to the irrigation scheme is delivery: recycled water, comprised of recycled water delivered to Virginia Pipeline Scheme and Willunga Basin Water Company from several wastewater treatment plants.  Other increases included recylced water delivered through community wastewater management systems during the 2015–16 year: 268 ML to Barossa Infrastructure Limited and 330 ML to Willunga Basin Water Company.

Non-allocated extraction: groundwater provided 310 ML of groundwater to Willunga Basin Water Company  through the Aldinga Aquifer Storage and Recovery Scheme (see Groundwater outflows). The volume delivered to Barossa Infrastructure Limited from the River Murray as delivery: inter-region, represents an increase of 17% compared with the previous year.

Delivery of water for irrigation was the only outflow reported for all irrigation schemes. The volume for the 2015–16 year comprised the delivery of 9,047 ML from Barossa Infrastructure Limited, 14,697 ML from Virginia Pipeline Scheme, and 5,071 ML from Willunga Basin Water Company. The total delivery of water to irrigation customers from these schemes was 6% more than the volume delivered in the 2014–15 year, continuing an increasing trend over the past three years.

Irrigation scheme balancing item

Closing the irrigation scheme balance required a balancing item of 2,066 ML (Table S8), which is approximately 5% of the total irrigation scheme inflows for the year. The misbalance may be due to a number of factors, such as metering inaccuracies and unaccounted losses.