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National Water Account 2019

South East Queensland: Water stores

  • Dry conditions contributed to very low runoff across the region and a decrease in storage volumes.
  • 87% of the region's total water supply was for urban use, mostly from surface water storages.
  • Water supply for urban use was 363 GL, about 8% higher than last year.

For a water balance on each of the region's water stores for the 2018–19 year scroll down this page or click on the links below:

 

Surface water store

Wivenhoe Dam, SEQ region (Seqwater © 2010)

 

Table S4 Water balance for the surface water store
Description Volume (ML)
  Opening surface water store 2,128,225
add Inflows 1,100,260
less Outflows 1,589,473
add Balancing item 22,516
  Closing surface water store 1,661,528

 

  • The volume of surface water in the region decreased from 2,128 GL at 1 July 2018 to 1,662 GL at 30 June 2019.
  • The balancing item is approximately 1% of the closing surface water store and is primarily attributed to uncertainties associated with the runoff estimate (see Methods).

 

Surface water flows

Figure S3 Water inflows and outflows for South East Queensland's surface water store during the 2018–19 year

 

  • The largest natural water flows were runoff and river outflow. Both were well below average due to the dry conditions experienced across the region (see Climate and water).
  • Total surface water diverted in the region was 385,112 ML.
  • 91% of the total surface water diverted was to the urban system by the Queensland bulk water supply authority, Seqwater.
  • 8% of the total diversion was for individual users (comprising allocated and non-allocated diversions) while 1% was for individual users under a statutory right.
  • For a more detailed description of the water usage in the region, and the associated entitlements, see the Surface water rights note.

 

Groundwater store

Thargomindah artesian bore, Queensland (istock © John Carnemolla)

 

Table S5 Water balance for the groundwater store
Description Volume (ML)
  Opening groundwater store 11,115
add Inflows 26,414
less Outflows 24,030
add Balancing item (2,384)
  Closing groundwater store 11,115

 

  • The volume of groundwater in the region is equivalent to the permissible consumptive volume, which is the legal extractable limit and, therefore, remains unchanged from year to year.
  • The balancing item is more than 20% of the closing groundwater store. The relatively large balancing item is due to the fact that groundwater fluxes such as recharge and discharge cannot be quantified, as well as the assumption of constant volume in the groundwater store.

 

Groundwater flows

Figure S4 Water inflows and outflows for South East Queensland's groundwater store during the 2018–19 year

 

  • Natural groundwater movement across the region boundary, as well as surface water–groundwater interactions, are considered to occur within the region; however, these flows could not be quantified due to a lack of available data.
  • Total groundwater extracted in the region was 24,030 ML.
  • 72% of groundwater extraction was for individual users (comprising both allocated and non-allocated extraction); 28% was used for the urban water system.
  • For a more detailed description of the water usage in the region and the associated entitlements, see the Groundwater rights note.

 

Urban water system

Brisbane River, SEQ region (istock © zstockphotos)

 

Table S6 Water balance for the urban water system
Description Volume (ML)
  Opening urban water system 0
add Inflows 615,136
less Outflows 596,101
add Balancing item (19,035)
  Closing urban water system 0

 

  • The volume of water in the region's urban system comprises water in the pipe network. As no major pipe network changes were made, this volume is assumed to remain unchanged throughout the year.
  • The balancing item is attributed to metering inaccuracies, unaccounted losses, and uncertainties in the estimation of certain volumes (see Methods).

 

Urban water system flows

Figure S5 Water inflows and outflows for the South East Queensland's urban water system during the 2018–19 year

 

Water supply inflows

Graph of water sources used in South East Queensland's urban water system during the 2018–19 year compared with the previous eight years Figure S6 Water sources used in South East Queensland's urban water system during the 2018–19 year compared with the previous eight years

 

  • Total inflow to the water supply system was 363,027 ML, approximately 8% higher than last year.
  • The increase in urban supply was influenced by the dry conditions across the region, which resulted in an increase in customer reliance on water from the urban system.
  • Surface water inflow made up 96% of urban supply; groundwater and desalinated water each made up 2% of the total.
  • The contribution of desalinated water to urban supply was the highest since 2010–11.

 

Wastewater and recycled water inflows

  • Wastewater collected was 252,109 ML during the 2018–19 year.

 

Water supply outflows

Graph of outflows from the water supply system
Figure S7 Outflows from the water supply system

 

  • The majority of water supply outflow was supply system delivery to urban users.
  • Approximately 10% of the total outflow from the urban supply system was related to losses.

 

Wastewater and recycled water outflows

Graph of outflows from the wastewater and recycled water systems

Figure S8 Outflows from the wastewater and recycled water systems

 

  • 7% of treated wastewater was recycled water delivery to urban users.
  • Most of the remaining treated wastewater was discharge to sea.