Ord
1.1 Storages

Supporting Information

The volume recognised in the water accounting statements (15,078,047 ML) represents the total volume of water held in storages that are used to administer water access entitlements at 30 June 2011. The volume includes the dead storage volume.

The 2010–11 year was relatively wet in the Ord region. Wet conditions meant an increase in the volume of water held in storages. Specific details of individual storages are provided in the table below.

 

Volumes in major storages of the Ord region

Storage name  

Total storage
capacity (ML)

Dead storage
capacity (ML)

Volume at 30 June 2011 (ML)

Volume at 30 June 2010 (ML)

Lake Argyle (1)

10,755,830

324,000

14,920,380

8,668,050

Lake Kununurra (1)

100,825

87,000

95,286

95,286

Moochalabra Dam (1)

2,023

175

1,931

1,871

Arthur's Creek Dam (2)

65,000

Unknown

60,450

44,200

Total

10,923,678

411,175

15,078,047

8,809,407

 Source: (1) Water Corporation, (2) Tropical Forestry Services

As dsecribed for the Bureau of Meteorology's water storage product, please note that an individual water storage may hold more than 100% of its accessible capacity on a given day. The volume of water above 100% is considered to be in transit rather than in storage.

Quantification Approach

Data Source

Water Corporation Operational Data Storage System database and Tropical Forestry Services

Provided by

Water Corporation and Tropical Forestry Services.

Method

At Water Corporation, storage volume is calculated at the start and end of the reporting period by using gauged water level height(s) (metres above Australian Height Datum) for individual storages. The height measurement is converted to a volume using the storage–volume curve(s) of the storage.

Tropical Forestry Services also use a gauge height measurement and convert that to a volume using a storage–volume relationship.

The storage volume of individual storages is aggregated to present the volume for the line item.

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. Uncertainty range +/–5%.

Comparative year

The following table compares the value for the 2009–10 year reported in this account with the corresponding value reported in the 2010 Account.

Comparative information from the 2010 Account for line item 1.1

2011 Account line item

2010 Account line item

Value reported in the 2010 Account (ML)

Value reported in the 2011 Account (ML)

Additional information

1.1 Storages

1.1 Storages – entitlement system

8,765,206

8,809,407

Change in line item name and number. Change in definition of one storage.

The volume of water held in storages at 30 June 2010 has been restated to include the volume stored in Arthur Creek Dam. This was 44,200 ML. Arthur Creek is a tributary of the Dunham River.  The storage is a large private storage with a total capacity of 65,000 ML. Water is diverted from the water storage under licence to Tropical Forestry Services Properties Pty Ltd, as trustee for the Kingston Rest Unit Trust, for the purpose of self-irrigation.

Arthur Creek Dam is included here because a present obligation can be discharged from the available water at the storage.