Ord
17.12 Entitled diversion of allocated surface water to urban water system

Supporting information

The volume recognised in the water accounting statements (422 ML) represents the volume of water diverted for urban water supply in the Ord region during the 2011–12 year.

Total surface water diverted from each surface water resource for urban water supply in the Ord region during the 2011–12 year is given in the following table.


Volume of water diverted from each surface water resource to the urban water system during the 2011–12 year

Surface water resource

Volume diverted (ML)

Moochalabra Dam – Wyndham town supply

401

Main Ord River – Lake Argyle Village supply1

21

Total

422

  1. Volume based on metered and estimated data (see 'Quantification approach')


Quantification approach

Data source

Operational Data Storage System.

Provided by

Water Corporation.

Method

Total water diverted from surface water resources for urban water supply within the Ord region is equal to the total annual water released from the resource during the 2011–12 year. The water volumes diverted are metered at the outlet continuously and reported on a monthly basis.

Where metered data were unavailable during the year (e.g. Lake Argyle Village supply), the volume of water diverted during the period of missing data was estimated based on the mean measured daily water abstraction.

Assumptions, limitations, caveats and approximations

Water diversion from the main Ord River channel for supply to Lake Argyle Village was based on both measured and estimated data. The volume of water supplied to Lake Argyle Village was measured for five months of the year (July–November 2011) on a daily basis. Data for the remainder of the 2011–12 year were unavailable. As the daily volume of diversion to Lake Argyle Village changes little throughout the year, the volume of water diverted during the period of missing data was estimated based on the mean measured daily water abstraction.

Uncertainty information

Expected error for water meters is +/– 5%.

The Department of Water requires that all water meters, when tested under in situ conditions, must be within 5% accuracy across the full flow rate range (Guidelines for water meter installation 2009).

Comparative year

This line item corresponds to line item '17.12 Surface water allocation diversion – urban water system' reported in the 2011 Account.