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Perth
1.1 Storages

Supporting information

The volume reported in the water accounting statements (183,415 ML) represents the total volume of water held in surface water storages within the Perth region at 30 June 2013. These storages are used for urban water supply and irrigation water supply (refer to Table P2 in the Physical information).

Total volume of water within each storage at 30 June 2012 and 30 June 2013 is given below. The individual storage volumes include the volume of dead storage.

 

Volume of water for each storage within the Perth region at the end of the 2012–13 and 2011–12 years

Storage

Capacity (ML)

Dead storage (ML)

Storage at 30 June 2013 (ML)

Storage at 30 June 2012 (ML)

Canning

90,300

60

16,652

26,279

Churchman Brook

2,200

40

893

911

Drakes Brook

2,300

20

1,508

1,995

Harvey

55,700

780

18,603

21,942

Logue Brook

24,200

380

3,703

3,512

Mundaring

43,000

20,560

23,923

25,454

North Dandalup

73,800

1,020

12,960

20,317

Samson Brook

7,900

90

521

377

Serpentine

136,700

1,010

31,880

33,819

Serpentine Pipehead

2,200

460

2,103

27

South Dandalup

125,100

12,940

12,937

11,953

Stirling

54,300

1,800

23,139

21,810

Victoria

9,400

50

4,275

4,821

Waroona

14,800

170

4,085

2,991

Wungong

56,400

3,430

26,233

33,247

Total

698,300

42,810

183,415

209,455


Overall storage volume for the Perth region at 30 June 2013 was 26% of capacity, a decrease of 4% from 30 June 2012. The figure below shows that water volume in most of the storages within the Perth region at the end of the 2012–13 year are less than that at the end of the 2011–12 year.

The decrease in surface water storage is primarily attributed to the decrease in inflows into the storages during the 2012–13 year compared to the comparison year (see Water Corporation website).


Graph of water volumes for each storage within the Perth region at the end of the 2011–12 and 2012–13 years. Capacity of each storage is also shown.
Graph of water volumes for each storage within the Perth region at the end of the 2011–12 and 2012–13 years. Capacity of each storage is also shown.

Quantification approach

Data source

Australian Water Resources Information System—water storages.

Provided by

Bureau of Meteorology.

Method

Storage volume at the start and end of the year was calculated using water level data (metres above Australian Height Datum) collected at each storage. Rating tables established for each storage by the Water Corporation were used to convert the height measurement to a volume.

The volume of individual storages was aggregated to present the total volume for the line item as detailed in the supporting information table.

Assumptions, limitations, caveats and approximations

Storage-volume curves represent specifically surveyed parts of the storage, and may not reflect the storage-volume relationship across the entire storage.

Storages are subject to sedimentation and other physical changes over time, which in turn affects the accuracy of the storage-volume curves.

Uncertainty information

Derived from measured data. Estimated uncertainty is +/– 5%.