South East Queensland
Water overview
Significant water events
While flooding in South East Queensland (SEQ) associated with Tropical Cyclone Oswald in late January 2013 made headlines, the total annual rainfall in the 2013–14 year was the ninth lowest year in 114 years (1900–2014) and fell well below the 10th percentile. In particular, the summer rainfall (December–February) in the region was well below the long-term average during a period when the majority of rainfall normally occurs.
Soil moisture
Figure W1 shows that soil moisture was generally average to below average in the SEQ region during the 2013–14 year, except for a small area along the coast where the soil moisture was very much below average (compared to the 1970–2014 period). The soil moisture is based on a simple conceptual representation of soil water storage and transfer processes averaged over a 5 km x 5 km grid cell derived from the Australian Water Resources Assessment system landscape model (AWRA–L) version 3.0. The model produces a soil moisture grid for the region at a daily time step, which is then averaged over the entire year to produce an annual soil moisture grid. The annual grid represents the mean daily volume of soil moisture across the region during the year.
Figure W1 Annual soil moisture deciles for the South East Queensland region during the 2013–14 year
Soil moisture distribution shown in Figure W1 aligns with well below average rainfall conditions experienced across the SEQ region during the 2013–14 year (see Rainfall in Climate overview). Below average rainfall and generally dry conditions in the soil translates into below average streamflows in the rivers.
Streamflow
There are four main river systems within the SEQ region:
- Albert
- Bremer
- Brisbane
- Logan.
More detail on these river systems, including location, is provided in the Surface water section of the 'Contextual information'.
Unlike the two previous years of 2011–12 and 2012–13, the annual flow for all the rivers during the 2013–14 year were much below the average annual flow that was impacted by low rainfall (see Rainfall in Climate overview) and soil moisture conditions across the region during the 2013–14 year (see Soil moisture).
Figures W2–W5 show that monthly flows in the four rivers were in general below average for all except: July for the Albert River, March for the Bremer River, and July and March for the Logan River. The average annual flow for the Albert River in 2013–14 decreased by 83% from the 2012–13 year, and by 93% for the Brisbane River, 90% for the Bremer River and 85% for the Logan River. These flow conditions reflect the below average rainfall conditions experienced across the SEQ region, except for November and March (see Climate overview). The above average rainfall in November and March 2014 did not result in above average streamflows in all four rivers, presumably because soil water stores and groundwater levels were relatively low after the 2013–14 dry summer period.
Figure W2 Total monthly flow along Albert River (Station 145102B) during the 2013–14 year compared with long-term percentiles
Figure W3 Total monthly flow along Bremer River (Station 143107A) during the 2013–14 year compared with long-term percentiles
Figure W4 Total monthly flow along Brisbane River (Station 143001C) during the 2013–14 year compared with long-term percentiles
Figure W5 Total monthly flow along Logan River (Station 145014A) during the 2013–14 year compared with long-term percentiles
Major water initiatives
During the 2013–14 year, the SEQ region received below average rainfall of 681 mm, equal to about two-thirds of the long-term average rainfall indicating a significant decrease in rainfall from the 2012–13 figure of 1,184 mm. Consequently, surface water storage volumes decreased from 99% to 89% of total capacity in the period from 30 June 2013 to 30 June 2014. Streamflows in the region's four main river systems during the 2013–14 was less than or equal to one-third of mean annual flow volumes.
Major water initiatives that were in the process of being investigated, designed, constructed, or commissioned during the 2013–14 year include:
- Seqwater commissioned the Kilcoy WTP that will provide reliable water supply for the Kilcoy community and local industries.
- Seqwater completed essential maintenance works at the historic Mt Crosby Eastbank WTP, shutting down the plant for the first time in more than 50 years and completing a series of upgrades without disrupting the water supply. The Mt Crosby assets are some of the most important assets in SEQ region's bulk water supply system, as they supply most of Brisbane and Ipswich’s drinking water. Seqwater also undertook vital repairs to Mt Crosby Weir following damage caused by tropical cyclone Oswald in January 2013. The work included the removal of a 22–tonne log wedged in one of the two intake pipelines and the stabilisation of the embankment with tonnes of rock.
- Seqwater commenced its Dam Improvement Program to ensure dams meet the latest national standards. Upgrades got underway at Moogerah and Maroon dams.
- Seqwater began development of SEQ region's next 30-year Water Security Program to ensure cost-efficient water supplies are available in the long term.
- The Fitzgibbon Stormwater harvesting (FiSH) Project is designed to harvest stormwater runoff from a catchment area of 290 ha within a residential development and to supply 89 megalitres/year of treated stormwater for nonpotable uses within the Fitzgibbon Chase estate development. The FiSH project was completed in March 2014 (Australian Government Department of the Environment 2015c).
The Logan Basin ROP amendment was approved in March 2014 and it provides for water trading by:
- increasing the number of non–urban surface water allocations through conversion of approximately 120 water licences in the Christmas Creek and Running Creek catchments into volumetric tradeable water allocations
- establishing trading zones and specified rules for trading these water allocations and seasonal water assignments
- establishing a minimum flow threshold to ensure environmental and stock and domestic needs are also met.
The Moreton ROP was approved in May 2014 and;
- defines rules for operation of the WSSs, such as seasonal water assignment rules
- provides for permanent allocations to be located in the Stanley River WSS to supply water to the townships of Kilcoy and Somerset
- provides for flood mitigation releases from dams
- grants ROLs to Seqwater for the Warrill Valley and Lower Lockyer Valley WSSs
- converts interim water allocations to tradeable water allocations
- amends unsupplemented water licences within the area of the Warrill Valley WSS to include volumetric limits.