17.2 River outflow from the region
This line item refers to the volume of water that flowed out of the Canberra region in the Murrumbidgee River during 2010–11. The volume reported for the 2010–11 year was 1,144,888 ML.
Outflow from the region was much greater in 2010–11 than 2009–10 due to significant flood events. More information on these flood events can be found in line item 17.5 Overbank flood spilling.
Map of the Canberra region showing key gauging stations on the Murrumbidgee River
The surface water flow out of the Canberra region was obtained from the gauging station at Halls Crossing (site ID 410777) on the Murrumbidgee River. Streamflow height was monitored at this site and converted to a flow volume using a rating table. The daily flow from this site during the 2010–11 reporting year was used to calculate the annual streamflow.
Assumptions, Limitations, Caveats and Approximations
- The stream gauging site is located 8 km downstream of the Canberra region boundary. Since the distance between the boundary and the site is short, it was assumed that minimal runoff was generated between the catchment boundary and the monitoring site
- 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 uncertainty estimate was not quantified.
This line item corresponds to line item 14.2 Surface water flow out of region reported in the 2010 Account.