Australia's inland waters

​​​The Water Quality Guidelines provide high-level guidance on the management context, ecological descriptions, biological indicator selection and other advice for 3 drainage divisions defined for high-spatial scale ecoregionalisation of Australia’s (non-estuarine) inland waters. Guidance for the other 9 drainage divisions will be added over time. We also provide advice on assessing and managing water quality in Australia’s temporary waters.

Find guidance for your drainage division

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Inclusion of Australia’s drainage divisions

Australia’s drainage divisions and river basins were defined by the Australian Water Resources Council (AWRC) in the 1960s. The drainage divisions comprise 245 river basins and were based on the continent’s major topographic features and climatic zones to give broadly homogenous hydrological regions.

As reviewed by Hale et al. (2012), the Australian Hydrological Geospatial Fabric (Geofabric) incorporates the most recent version of the drainage divisions and river basins, and provides a lower level of nested catchments and river nodes and increasingly finer scales, down to individual river reaches (BoM 2011).

The Australian Government has adopted drainage divisions as the best-fit national regionalisation for inland aquatic ecosystems through a number of programs, such as High Ecological Value Aquatic Ecosystems (HEVAE), Ramsar Convention on Wetlands and national (State of the Environment) water quality assessments (Hale et al. 2012).

Australia’s drainage divisions have undergone modifications, mainly a result of improved mapping of the inland arid zone area. The Tanami–Timor Sea Coast division was included in 2012, as represented under the Australian Hydrological Geospatial Fabric (Geofabric) (PDF 922KB).

Stein et al. (2014) highlighted shortcomings of the continental drainage divisions for planning and assessment of Australia’s water resources:

  • topographically defined hydrological boundaries not always adhered to
  • classification does not recognise the distributaries that link many major river systems
  • river basins confuse a number of spatial scales and are too coarse for many water resource assessment needs.

Modifications to, and limitations of, the regionalisation are noted but we have adhered to the original mapping and delineation of the 12 drainage divisions (AWRC 1976) for ecoregional purposes. The drainages are deemed fit for purpose and commensurate with the coarse scale at which regional guideline values and advice are being provided for users.

The Bureau of Meteorology provides a detailed map of Australia’s drainage divisions and river regions.

Australia’s temporary waters

Temporary waters are a very significant regionalisation considered in the Water Quality Guidelines. These inland waters may be:

  • streams — alternating between flowing and either no-flow or dry-stream bed
  • standing waters — alternating between inundated or dry
  • intermittent (recurrent) — flowing or inundated predictably every wet season
  • ephemeral (fleeting) — flowing or inundated only after episodic rainfall.

Surface waters of Australia’s arid regions (average < 250 mm rainfall per year) and semi-arid regions (average 250 to 350 mm rainfall per year) typify temporary inland waters (Figure 1), but they are not exclusive to these regions.

For example, average annual rainfall may be much higher over the intermittent systems of northern Australia (wet–dry tropics) and parts of far-southern mainland Australia.

We provide advice on assessing and managing water quality in temporary waters that is relevant to all aquatic ecosystems of drainage divisions within arid and semi-arid zones. Our guidance includes general descriptions and advice for water quality (including biological) assessments but not water quality guideline values.

Figure 1 Extent of arid and semi-arid regions in Australia. Source: Bureau of Meteorology

Less national guidance is available on conducting water/sediment quality assessments for ephemeral surface waters and waterbodies of arid and semi-arid Australia than for intermittent and seasonal waterbodies outside these climatic zones.

References

AWRC 1976, Review of Australia’s Water Resources 1975, Australian Water Resources Council, Department of National Resources, Australian Government Publishing Service, Canberra.

BoM 2011, Australian Hydrological Geospatial Fabric (Geofabric) Data Product Specification, Version 2.0. Bureau of Meteorology, Canberra.

Hale, J, Butcher, R, Collier, K & Snelder, T, 2012, ANZECC/ARMCANZ Water Quality Guidelines Revision: Ecoregionalisation and Ecosystem Types in Australian and New Zealand Marine, Coastal and Inland Water Systems, report prepared for the Australian Government Department of Sustainability, Environment, Water, Population and Communities, Canberra.

Stein JL, Hutchinson MF & Stein JA, 2014, A New Stream and Nested Catchment Framework for Australia,​ Hydrology and Earth System Science 18: 1917–1933.