The volume presented in the water accounting statements (686,630 ML) represents the volume of water held in surface water storages in the Melbourne region at the end of the 2011–12 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.
|Storage operator||Storage||Total storage capacity (ML)||Dead storage (ML)||Storage volume at 30 June 2011 (ML)
||Storage volume at 30 June 2012 (ML)
|Melbourne Water||Cardinia Reservoir||288,964||2,053||206,406||219,792|
|Upper Yarra Reservoir||204,985||4,406||142,602||14,8319|
|Yan Yean Reservoir||33,125||2,859||30,229||30,307|
|Southern Rural Water||Melton Reservoir||14,360||140||13,577||13,992|
|Pykes Creek Reservoir||22,119||1,770||28,092||21,637|
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 converting 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 rounding and uncertainty in the true values.
The volume was estimated from measured data.
In the 2011 Account, the volume of water in surface water storages was compiled from two data sources:
- The storage volumes for Melbourne Water managed storages were obtained from the water storages product (see Quantification approach).
- The storage volumes for Southern Rural Water managed storages were obtained directly from Southern Rural Water.
Following publication of the 2011 Account, Southern Rural Water provided storage data to the water storages product for the 2011 year and these volumes have been retrospectively updated in the 2012 Account. The difference in the values published in the 2011 account compared to the 2012 Account may be due to the updated values sent by Southern Rural Water.
Consequently, the volume has been restated from 669,642 ML (as published in the 2011 Account) to 671,747 ML as shown in the following table.
|Storage operator||Storage||2012 Account volume
at 30 June 2011 (ML)
|2011 Account volume
at 30 June 2011 (ML)
|Melbourne Water||Cardinia Reservoir||206,406||206,406|
|Upper Yarra Reservoir||142,602||142,602|
|Yan Yean Reservoir||30,229||30,229|
|Southern Rural Water||Melton Reservoir||13,577||13,577|
|Pykes Creek Reservoir||28,092||22,119|