9.2 River inflow to region

Supporting information

This line item refers to the volume of surface water that flowed into the Canberra region from the upstream Murrumbidgee River.

The volume recorded at Murrumbidgee at Angle Crossing (Gauge number 41001702) is 582,184 ML.

Quantification approach

Data source

Stream gauge data (Gauge number for the Murrumbidgee at Angle Crossing 41001702).

Provided by

ACTEW Water.


The connected surface water flow from the upstream entity was obtained from the gauging station at Angle Crossing. The station is approximately located on the Australian Capital Territory border, downstream of the Canberra region boundary.

Assumptions, limitations, caveats and approximations

  • The level of uncertainty of the Murrumbidgee Angle Crossing is estimated at +/– 20 % during low to medium flows and the uncertainty during high flows is ungraded. This is based on four manual physical flow calibrations performed per year. At these sites the water surface level is measured constantly by on-site equipment. This water level is used to estimate a flow rate, based on a rating curve produced by physical flow gauging in as many flow conditions as possible.

  • There is some uncertainty in the flow rates, as there is an inherent level of uncertainty in the physical flow gauging process. The river flows have not been gauged under all flow conditions, and the river channel can change from time to time, due to deposition and movement of river sediments and growth and removal of riparian vegetation, which may impact both the cross-sectional area of the channel available for river flow and the velocity of the water.

  • The gauge ID number of the Angle Crossing site in the 2010–11 Account was MURWQ09 and it has been changed to 41001702 during the 2011–12 year.

Uncertainty information

The uncertainty estimate was not quantified.

Comparative year

River inflow to region was recalculated due to updates of the hydstra data through the data validation process and updates of the rating table. Consequently, the comparative year value has been restated in the water accounting statements from 279,762 ML (as published in the 2011 Account) to 287,899 ML.