Sydney
1.2 Unregulated river

Supporting information

The the volume of water stored in unregulated river channels on 30 June 2013 was 25,162 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 2012–2013 year.


Breakdown of rivers of the Sydney region

River1

From

To

Volume (ML)

30 June 2013

Volume (ML)

30 June 2012

Capertee

Glen Davis

Upper Colo

915

483

Coxs

Lithgow

Kelpie Point

2,055

559

Shoalhaven

Kadoona

Fossickers Flat

22,192

1,947

Wollondilly

Jooriland

Golden Valley


996

Total

25,162

3,985


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' in Water accounting policies.

Quantification approach

Data source

Hydstra and Computer Aided Improvements to River Operations databases.

Provided by

New South Wales Office of Water.

Method

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


Formula symbols

Symbol

Variable

Unit

Q

Average flow in the river section calculated by averaging the daily flows at the upstream and downstream river gauges

ML/day

V

Volume in each river section

ML

T

Average travel time for a parcel of water to travel through the river section

days

Assumptions, limitations, caveats and approximations

  • 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, and Wollondilly River from Jooriland to Golden Valley)
  • Shoalhaven River, except the reach from Kadoona to Fossiker's Flat
  • northern Sydney rivers
  • southern Sydney rivers
  • Illawarra rivers.

Uncertainty information

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.