Australia’s water resources


Drainage divisions are the fundamental spatial unit for assessing the state of the inland water environment. As discussed in SoE 2011, these provide a scale of resolution that supports assessment of the health of entire systems, while recognising the variations and variability that lie within.

Four changes have occurred to the interim Australian drainage divisions used in 2011:

  • The South East Coast division was divided into 2 divisions: South East Coast (New South Wales), covering catchments north from Towamba River, and South East Coast (Victoria), covering catchments west from the East Gippsland river region.
  • The Gulf of Carpentaria division was renamed the Carpentaria Coast division.
  • The Indian Ocean division was renamed the Pilbara–Gascoyne division.
  • The Timor Sea division was renamed the Tanami–Timor Sea Coast division.

These updated divisions, shown in Figure WAT1, are used in this report.

Australia is the world’s second driest continent, after Antarctica, with a long-term average rainfall of 430 millimetres (mm) and variations ranging across Australia from below 100 mm to above 3000 mm per year (Figure WAT2). Most of this is lost through evapotranspiration (loss of water from Earth through evaporation and transpiration from plants), and the annual average run-off coefficient (a measure comparing the amount of run-off with the amount of precipitation) is about 12 per cent. Thus, on average, some 383,000 gigalitres (GL) remain after evapotranspiration to enter Australian water environments, of which around 70,000–95,000 GL is used each year to meet Australia’s consumptive water needs.

Argent RM (2016). Inland water: Australia’s water resources. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra,, DOI 10.4226/94/58b656cfc28d1