A summary of the significant water events, major water initiatives and improvements in water information occurring during the reporting period are explained.
For the three inter-valley water transfer systems relevant to the Melbourne region, the volume of water imported by each during 2009–10 was:
During 2009–10, trading occurred from the Thomson Reservoir to the Bacchus Marsh Irrigation District (737 ML). This trade was made as a drought response and is not a usual occurrence.
The Thomson-Yarra Tunnel connects Thomson Reservoir to the northeast of the Melbourne region, to the Upper Yarra Reservoir within the Yarra catchment. The Thomson Reservoir has a total capacity of 1,068,000 ML.
Thomson Reservoir and the water transfers through the Thomson-Yarra Tunnel are managed by Melbourne Water. Melbourne Water is able to transfer water from the Thomson Reservoir to the Upper Yarra Reservoir as it sees fit, subject to the conditions specified in the Thomson River Bulk Entitlement held by the retail water companies.
The North-South Pipeline allows the transfer of water from the Goulburn catchment to Sugarloaf Reservoir in the Melbourne system. Water sourced from the Goulburn catchment is Melbourne’s share of savings made in the Northern Victoria Irrigation Renewal Project. This water is stored in Eildon Reservoir and released at Melbourne Water’s request to the Goulburn River for transport to the pipeline intake.
Qualifications of Entitlements
In recent years, Victoria’s continuing drought conditions demanded that environmental water shares be used to ensure critical human needs were met in some urban centres. The Victorian Minister for Water, under the powers of the Water Act 1989 (Victoria) declared a water shortage and qualified rights to enable changes to bulk entitlement conditions to be made as an emergency management measure.
In 2007, the Victorian Minister for Water qualified rights in the Yarra and Thomson Rivers. In April 2010, following significant rainfall in the region, these qualifications were lifted.
Major projects relating to water supply augmentation in the region include the North-South pipeline and the Wonthaggi desalination plant.
The North-South pipeline enables the transfer of water from Lake Eildon in the northeast of Victoria to Sugarloaf Reservoir. Operation of this pipeline commenced in April 2010. Funding of the $750 million pipeline budget was made by Melbourne’s water users through Melbourne Water. In any one year, Melbourne will take not more than 75,000 ML via the North-South pipeline.
The Wonthaggi desalination plant is being built and operated by a private consortium and will supply water to the Melbourne region from the end of 2011. The plant is scheduled to produce 150,000 ML/year. The project will be delivered through a Public Private Partnership with the AquaSure consortium. Degrémont Thiess Services will be responsible for the operation and maintenance of the plant and pipeline to July 2039.
The Melbourne-Geelong pipeline is being built to enable the transfer of water from the Melbourne pool, including Goulburn, Thomson and desalination sources, to Geelong. The pipeline is scheduled to begin operation in 2011, with Barwon Water entitled to take 16,000 ML/year. The Victorian Government will contribute $20 million. The remaining $117.9 million will be provided by Geelong water users through Barwon Water.
Key improvements in water information during the reporting period were:
Deployment of Doppler acoustic technology
The application of acoustic Doppler technologies provided a valuable tool to quantify the impact of complex flow conditions on the accuracy of hydrographic data collection across Victoria. During 2009–10, in situ acoustic Doppler velocity meters were deployed at selected gauging sites to collect flow data during floods, so that the reliability of flood estimates could be improved.
It is practically impossible to estimate true flow in a stream at a gauging station. However, estimates of the error associated with a reported flow (uncertainty) can be made. A study into the calculation of data uncertainty for flow monitoring was undertaken through collaboration between the Department of Sustainability and Environment, Thiess Services and the Centre for Applied Environmental Hydrology at the University of Melbourne during 2005–06. The study has continued to raise awareness of the importance of understanding and estimating uncertainty at monitoring sites within Victoria, and informed ongoing initiatives to improve measurement across the State’s monitoring network.
Enhancements to chart of water accounts
Work to develop a comprehensive chart of accounts for Melbourne to improve the recording and reporting of water information in water accounting reports commenced. This has contributed to a more detailed understanding of the management of water within the region and how best to account for it.