31.3 Off-channel water abstraction

Supporting information

The volume reported (6,248 ML) represents the volume of water abstracted from off-channel water stores for use during the 2012–13 year. Note that metered water diversions from on-channel private storages connected to the watercourses in the Barossa Prescribed Water Resources Area area included in the volume of line item 17.11 Entitled diversion of allocated surface water to users.

Quantification approach

Data source


Provided by

Bureau of Meteorology.


The farm dam algorithm written by the Bureau of Meteorology was used to determine the volume of water abstracted from the private water store. Data input to the model included gridded climate datasets, runoff from the AWRA-L version 3.0 (Van Dijk 2010) model, and dam details derived from spatial data (surface area, volume, location and catchment area). Model parameters included irrigation demand factors (Binks 2004) and stock and domestic demand factors (Luke 1987).

The Adelaide region was split into two subregions for the purpose of estimating the water balance of the off-channel water store. The region was divided using the boundaries of the AHGF contracted catchments between McLaren Vale and the Onkaparinga Valley. The northern region includes the Barossa Valley, the Northern Adelaide Plains, and the River Torrens, Patawalonga and the Onkaparinga catchments. The southern region includes catchments throughout McLaren Vale and the Fleurieu Peninsula. 


The farm dam algorithm written by the Bureau of Meteorology determines the water stored in each off-channel water store at each time point and determines the volume required for use from the off-channel water store. The algorithm assumes that water will be abstracted from the off-channel water store at the rate required unless off-channel water store empties, at which time, abstraction will cease.

Assumptions, limitations, caveats and approximations

  • The estimated volume available in storage for evaporation is subject to the assumptions associated with the farm dam algorithm written by the Bureau and the parameters used.

Uncertainty information

The uncertainty estimate was not quantified.