9.2 River inflow to region
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.
Stream gauge data (Gauge number for the Murrumbidgee at Angle Crossing 41001702).
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.
The uncertainty estimate was not quantified.