The volume presented in the water accounting statements (669,642 ML) represents the volume of water held in surface water storages in the Melbourne region at the end of the 2010–11 year.
The volume presented is the sum of the volume held in water storages that have a total storage capacity over 1,000 ML, including the volume of dead storage. The following table presents a breakdown of individual storages in the Melbourne Region.
|30 June 2010||30 June 2011|
The volume of water held in water storages increased significantly between the start and end of the reporting period. Very high rainfall, generated by one of the strongest La Nina events on record, resulted in water storages recording their highest inflows since the drought commenced in 1997.
Thomson Reservoir is not included in the storages as it is located outside of the Melbourne region boundary.
Storage volume was measured at the start and end of the reporting period by using gauged water level height(s) in metres, Australian height datum (mAHD) for individual storages. The height measurement was converted to a volume using the storage-volume curve(s) provided by the managing authority.
Storage capacity was calculated using the full supply level (FSL), and coverting it to a volume using the storage volume curve(s) provided by the managing authority.
Assumptions, Limitations, Caveats and Approximations
Storage-volume curves represent specifically surveyed parts of the water storage, and may not reflect the storage-volume relationship across the entire storage.
Water storages are subject to sedimentation and other physical changes over time, which in turn affect the accuracy of the storage-volume curves.
Storage capacity may differ from those published on the Water storages page of the Southern Rural Water website due to to rounding and uncertainty in the true values.
Southern Rural Water recognise different volumes for managing water allocations according to the Werribee & Bacchus Marsh Allocation Method.
The volume was estimated from measured data.
This item corresponds to line item 1.1 Storages – entitlement system reported in the 2010 Account. Following publication, an error was identified in the volumes reported in the 2010 Account that caused the 2009–10 year value to be restated; the volumes reported did not include dead storage as required by the Exposure Draft of Australian Water Accounting Standards 1.
This change and the respective values are detailed in the following table. The restated comparative year volume at 30 June 2010 is 400,646 ML.
2010 Account line items
Volume at 30 June 2010 reported in 2010 Account (ML)
Value difference due to prior period error correction (ML)
Volume at 30 June 2010 reported in 2011 Account (ML)
1.1 Storages – entitlement system