South East Queensland: Outlook 2016–17
Average rainfall conditions are expected across the South East Queensland region during the 2016–17 year, which may contribute to an increase in surface water storage. Water use during the year is expected to be similar to the 2015–16 year.
Future prospects
This section looks forward 12 months and considers what water inflows and commitments might affect the region's water resources during the 2016–17 year. Figure S20 shows that there is a surplus of available water assets and future water rights over water liabilities and future water commitments that are expected to be settled within 12 months of the reporting date.
Figure S20 Water outlook for the South East Queensland region for 2016–17
Expected inflows
At the time of publication, rainfall over the South East Queensland region during the first nine months of the 2016–17 year (July–March) was generally average across most of the region (Figure S21). A large portion of the rainfall during these nine months occurred in late-March as a result of ex-Cyclone Debbie. According to the Seqwater website, storage volumes at 1 April 2017 were 78% full compared with 85% full at the same time last year; however, storage volumes are likely to increase further during April 2017.
Figure S21 Rainfall deciles for the South East Queensland region from July 2016–March 2017
The Bureau's climate outlook (released on 30 March 2017) indicates a high probability of average rainfall along the east coast of Australia, including the South East Queensland region, for the next three months (April–June 2017). This outlook is influenced by warming of tropical Pacific sea surface temperatures and a cooler than average eastern Indian Ocean. Therefore, given the current average soil moisture conditions across the region in March 2017 (see the Bureau's Australian Landscape Water Balance product), annual streamflows and storage inflows are expected to be average during the 2016–17 year.
The expected inflows for the 2016–17 year are based on the 2014–15 year; a period when similar average rainfall and soil moisture conditions were experienced. Overall, the combined expected precipitation (approximately 200,000 ML) and river inflows into the storages (approximately 700,000 ML) should exceed the expected evaporation from the storages (approximately 330,000 ML) during the year.
Future commitments
The expected diversions and extractions are based on water use data for the 2015–16 year; however, given the average climate conditions expected across the region, water use is expected to remain similar over the next reporting period, particularly for urban water supply.
Contingent water assets
Desalinated water
Desalinated water is blended with other Gold Coast water supplies and joins the South East Queensland Water Grid. The region's storages have been full or near full since December 2010, hence the plant has been operating in 'hot standby' mode since that time to minimise operating costs. Under this mode, the plant produces 25 ML/day, twice a week. This small amount of production is necessary to keep the membranes wet and the water in the pipes fresh while retaining the capacity to increase production to 44ML/day within 24 hours and 133ML/day within 48 hours. The plant may also be called on if there are interruptions to supply in other parts of the SEQ Water Grid.
The contingent water asset associated with the Gold Coast desalination plant is the difference between the maximum operating capacity (133 ML/day) and the minimum operating rate (7 ML/day average based on hot–standby mode) and equates to 126 ML/day.
The non–extractable portion of groundwater
The groundwater management area (GMA) of the Lockyer Valley located within the Moreton water resource plan (WRP) area and Cooloola Sandmass subartesian aquifer were the only aquifers included as a store in the water accounting statements. Within the benefitted area of the Central Lockyer Valley water supply scheme, a groundwater limit exists, which defines the entitled maximum volume that can be extracted from the benefitted area of the aquifer as 9,340 ML. Similar groundwater limit exists for Cooloola Sandmass aquifer and its maximum entitled volume that can be extracted is 1,775 ML.
The remaining portion of the groundwater within these two aquifers and all other groundwater within the South East Queensland region is considered a contingent water asset.
It is possible that a change in circumstances, including legislative or regulatory changes that alter the extraction limits, such as the setting of volumetric extraction limits within the non-benefitted area of the Lockyer Valley groundwater aquifer, would result in further portions of the groundwater being included as an asset. There is no estimate available of the total volume stored in groundwater aquifers of the South East Queensland region.