31.3 Water use
This line item refers to the water used from Off–channel water storages. The volume reported for 2011 was 4,892 ML.
The STEDI model (Sinclair Knight Merz 2011) was used to determine the volume of water abstracted from the private water store. The model was provided inputs in the form of climate from gridded climate datasets, runoff from the AWRA-L v1.0.0 (Van Dijk 2010) model and dam details derived from spatial data. The model was parameterised with the same parameter set agreed on between the Bureau of Meteorology and the South Australian Department for Water for the National Water Account 2010.
The Canberra region was divided up into five subregions for the purpose of estimating the water balance of the private store. The four of the subregions were the catchments of the major storages and the fifth was the remaining land.
The private store consisted of off–channel storages filled primarily by rainfall-runoff. These were determined from waterbody mapping provided by Geoscience Australia and were waterbodies that were greater than 50 m from built-up areas in the Canberra region.The STEDI model determines the water stored in each private reservoir at each time point and determines the volume required for use from the reservoir. STEDI assumes that water will be abstracted from the reservoir at the rate required unless reservoir empties, at which time, abstraction will cease.
Assumptions, Limitations, Caveats and Approximations
- The gridded climate input data are subject to approximations associated with interpolating observation point data to a national grid detailed in Jones et al. (2007).
- The estimated volume available in storage for evaporation is subject to the assumptions associated with the STEDI model and the parameters used.
- The spatial extent of waterbodies subject to the assumptions and methods associated with the data provided by the Geoscience Australia.
The uncertainty estimate was not quantified.