Murray-Darling Basin
31.3 Water use

Supporting Information

The volumetric value for the line item for the 2010–11 year was 1,043,431 ML. The line item includes volume of water abstracted from off-channel water storages within the Murray–Darling Basin (MDB) region. The following table presents breakdown information for the line item on a surface water resource plan area basis.


Abstraction from off-channel water storages in the MDB region for the 2010–11 year
Surface water resource plan area


Volume (ML)   



SW 11–12 and SW17–19 Warrego – Paroo – Nebine, Condamine–Balonne, Moonie, NSW Intersecting Streams and Barwon–Darling watercourse Qld and NSW 254,896
SW 15–16 Qld and NSW Border Rivers Qld and NSW 74,467
SW14 Gwydir NSW 35,690
SW13 Namoi NSW 69,037
SW10 Macquarie–Castlereagh NSW 132,416
Sub-total Northern Basin 566,505
SW9 Lachlan NSW 113,637
SW 1 and 8 Murrumbidgee NSW and ACT  NSW and ACT 121,340
SW 2, 4, 5 and 7 NSW Murray and Lower Darling, Vic Murray, SA Murray and Wimmera–Mallee  NSW, Vic and SA 79,472
SW3 Northern Victoria Vic 149,626
SW6 Eastern Mount Lofty Ranges SA 12,851
Sub-total Southern Basin 476,926
Total for the region 1,043,431


Quantification Approach

Data Source

(1) Bureau of Meteorology (the Bureau): National Climate Centre daily climate grids (rainfall, temperature and solar radiation), (2) Commonwealth Scientific and Industrial Research Organisation (CSIRO): WaterDyn and Australian water resource assessment – landscape (AWRA-L) model parameters, and monthly climatological average radiation grid data, and (3) Geoscience Australia: MDB human-made waterbody feature class and 9 arc-second digital elevation model (DEM).

Provided by

The Bureau.


The tool for estimating dam impacts (STEDI) model (Sinclair Knight Merz 2011) was used to determine the volume of water abstracted from the off-channel 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 MDB region was divided into 105 units for the purpose of modelling the off-channel water store. The off-channel water store consisted of storages filled primarily by local catchment runoff. These were determined from waterbody mapping conducted by Geoscience Australia as those that:

  • are not named storages (assuming that any storage with a name is unlikely to be a off-channel water storage)

  • are above 600 m in elevation

  • are below 600 m in elevation in areas that receive greater than 400 mm per annum in precipitation and are not within 50 m of a major or perennial stream.

The above rules attempt to divide storages into those that are likely to be filled primarily by local catchment runoff and those that are filled by abstraction from surface water, groundwater or floodplain harvesting. The catchment of each individual storage was determined via analysis of the 9 arc-second DEM.

The STEDI model determines the water stored in each off-channel water storage at each time step and determines the volume required for use from the storage. STEDI assumes that water will be abstracted from the storage at the rate required unless storage 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 water bodies subject to the assumptions and methods associated with the data provided by Geoscience Australia.

Uncertainty Information

The uncertainty estimate was not quantified.


Comparative year

In the 2011 Account, the following changes were made that caused the 2009–10 year value to be restated:

  • The scope of the line item was changed.

  • The methodology used to quantify the line item was improved and resulted in a material change in volume.

The change in the values for 2009–10 was due to a combination of the exclusion of off-channel storages that are not filled by local catchment runoff and the use of AWRA-L model to estimate rainfall-runoff into local catchment storages. Modelling changes were made to provide more reliable estimates of runoff volumes. The difference of 830,663 ML represents a change of approximately 56% of the volume provided for the 2010 Account. The changes and their respective values are detailed in the following table.


Restatement of comparative year information made for the line item 31.3 Water use

Volume for the 2009–10 year reported in the 2010 Account (ML)

Difference due to change in the calculation method (ML)

Volume for the 2009–10 year reported in the 2011 Account (ML)

Northern Basin 787,355 –456,019 331,336
Southern Basin 690,943 –374,643 316,300
Whole region 1,478,298 –830,663 647,635