Sydney
1.2 Unregulated river

The the volume of water stored in unregulated river channels on 30 June 2012 was 3,985 ML, as detailed in the following table. The volume is an instantaneous estimate of static volume held in the river reaches. It is not the total volume flowing past a point during the 2011–2012 year.

1 Only the river sections for which data was available are included. Information about the river sections that were identified as water assets but could not be quantified is provided in 'Water assets and water liabilities that fail the recognition criteria'.

2 The volume stated for the Shoalhaven River on 30 June 2011 does not include the volume of water that was quantified between the gauging sites of Grass Gully No. 2 and Fossickers Flat as this data was unavailable. Grass Gully No.2 is situated upstream of Fossickers Flat and the volume quantified between the two sites contributes approximately 24% of the total volume for Shoalhaven River.

Derived from measured data.

For each river section S(n):

V = Q × T

The river channel storage will be equal to the sum of all river section volumes.

River channel storage = Sum of  V

• Travel times are estimated to the nearest day.
• Daily flow change between gauging sites is assumed to be linear.

Volume of water stored in the unregulated river channel is not estimated for the following rivers because reliable data were not available:

• Hawkesbury and Nepean rivers (except Capertee River from Glen Davis to Upper Colo, Coxs River from Lithgow to Kelpie Point, Macdonald River from Howes Valley to St Albans, and Wollondilly River from Jooriland to Golden Valley)
• Shoalhaven River, except the reach from Kadoona to Grass Gully No. 2
• northern Sydney rivers
• southern Sydney rivers
• Illawarra rivers.

The volume is estimated from measured data. Estimated uncertainty is in the range +/– 50%, based on professional judgment with conservative uncertainty estimates of +/– 10% and +/– 50% for flow data and travel time, respectively.