Melbourne
17.7 Non-allocated diversions to users

Supporting Information

The volume presented in the water accounting statements (16,883 ML) represents the volume of water diverted in the Melbourne region for irrigation, stock and domestic (stock and domestic), commercial and industrial and other surface water entitlements without prior allocation announcement.

The volume presented for irrigation does not include:

The following presents the licensed volume of entitlements in the Melbourne region and the volume diverted during the 2010–11 year.

Licensed entitlements and volume diverted in the Melbourne Region during 2010–11 year

Catchment


Class Bunyip Yarra Maribyrnong Werribee All catchments
Licensed
volume (ML)
Irrigation 17,759 20,300 3,512 2,032 43,603
Stock and domestic 652 735 329 31 1,747
Commercial and Industrial. 488 2,581 54 251 3,374
Other 550 19,774 23 n/a 20,347
Total licensed volume (ML) 19,449 43,390 3,918 2,314 69,071
Metered
diversions (ML)
Irrigation 1,984 3,464 300 262 6,010
Stock and domestic 0
6 0
0
6
Commercial and industrial 0
1,310 15
0
1,325
Other 0
7,248 n/a n/a 7,248
Total metered diversions (ML) 1,984 12,028 315 262 14,589
Estimated
non-metered
diversions (ML)
Irrigation 0
n/a 0
0
0
Stock and domestic 652 0
305 31 988
Commercial and industrial 488 0
17 251 756
Other 550 n/a n/a n/a 550
Total estimated diversions
(ML)
1,690 0 322 282 2,294
Total diversions (ML) 3,674 12,028 637 544 16,883

Quantification Approach

Data Source

Melbourne Water (Yarra catchment) Southern Rural Water (Bunyip, Maribyrnong and Werribee catchments).

Provided by

Victorian Department of Sustainability and Environment.

Method

The volume presented for this item is a combination of metered diversion data and estimates of non-metered diversions.

Metered diversions

Approximately 65% of licences in the Melbourne region are metered, as shown in the following table.

Licensed volumes and portion that were metered in the Melbourne Region during 2010–11 year

Catchment


Class Bunyip Yarra Maribyrnong Werribee All catchments
Licensed
volume (ML)
Irrigation 17,759 20,300 3,512 2,032 43,603
Stock and domestic 652 735 329 31 1,747
Commercial and Industrial 488 2,581 54 251 3,374
Other 550 19,774 23 n/a 20,347
Total licensed volume (ML) 19449 43,390 3,918 2,314 69,071
Licensed
volume that is metered (ML)
Irrigation 11,933 16,980 2,454 1,355 32,722
Stock and domestic 0 138 0 0 138
Commercial and industrial 0 2,365 0 0 2,365
Other 0 13,858 n/a n/a 13,858
Total licensed volume metered (ML) 11,933 33,341 2,454 1355 49,083
Licensed
volume that is metered
(% of licensed volume)
Irrigation 67% 84% 70% 67% 75%
Stock and domestic 0% 19% 0% 0% 8%
Commercial and industrial 0% 92% 0% 0% 70%
Other 0% 70% n/a n/a 68%
Total metered portion (%) 61% 77% 63% 59% 71%


Where metered data were available, the diversion was calculated as the actual diversion for the 2010–11 year. The following table shows the portion of diversions that were metered during the 2010–11 year.


Total diversions and the portion that were metered in the Melbourne region during 2010–11 year

Catchment


Class Bunyip Yarra Maribyrnong Werribee All catchments
Total diversions (ML) 3,674 12,028 637 544 16,883
Metered
diversions (ML)
Irrigation 1,984 3,464 300 262 6,010
Stock and domestic 0 6 0 0 6
Commercial and industrial 0 1,310 15 0 1,325
Other 0 7,248 n/a n/a 7,248
Total metered diversions (ML) 1,984 12,028 315 262 14,589
Metered
diversions (% of total diversions)
Irrigation 54% 29% 47% 48% 36%
Stock and domestic 0% 0% 0% 0% 0%
Commercial and industrial 0% 11% 2% 0% 8%
Other 0% 60% n/a n/a 43%
Total metered diversions
(% of total diversions)
54% 100% 49% 48% 86%


Un-metered estimated diversions

Where metered data were not available, the diversion was estimated using the following assumptions:

  • Diversion volume was assumed to be equal to zero for licenses in the Yarra catchment (as per Melbourne water assumptions).
  •  Diversion volume was assumed to be equal to the licensed entitlement volume for licences in the Bunyip, Maribyrnong and Werribee catchments (as per Southern Rural Water assumptions).

Assumptions, Limitations, Caveats and Approximations

Broad assumptions have been made to estimate unmetered diversions.

  • The assumption that the volume diverted under licensed entitlements in the Bunyip, Maribyrnong and Werribee catchments is equal to the entitlement volume is likely to overestimate the actual diversion.
  • The assumption that the volume diverted under licensed entitlements in the Yarra catchment is equal to zero is likely to underestimate the actual diversion.

Uncertainty Information

Metered diversions have an uncertainty of +/– 10% due to known errors of meters.

Unmetered estimates of diversion were not quantified.

Comparative year

This item corresponds in part to line item 14.6 Entitled diversion of unregulated surface water flows reported in the 2010 Account. In the 2011 Account, presentation of the line items has changed since the 2010 Account, which has caused the 2009–10 year value to be restated. Line items 14.6.1 Diversion of unregulated flows – Stock and domestic water access entitlement and 14.6.5.6 Diversion of unregulated flows – other lumped holders were merged into a single line item: 17.7 Non-allocated diversions to users.

The restated comparative year volume is 25,745 ML and is the sum of volumes reported at line items 14.6.1 (1,007 ML) and 14.6.5.6 (24,738 ML).