© Commonwealth of Australia, Bureau of Meteorology, 1991.

Definition of Drought

There have been several definitions of drought, none of which has been completely satisfactory. The simple description, "Dryness due to a lack of rain" for example, could be applied to many inland areas where such conditions would be regarded as normal rather than a drought situation.

The most satisfactory definition depends on the acceptance of drought as a supply and demand phemomenon. Thus, drought occurs when there is "lack of sufficient water to meet normal requirements." However, what is drought to one section of the community (e.g., a market gardener) may not be regarded as drought by another (e.g., a sheep farmer).

The 1982-83 Drought

Eastern Australia suffered an extensive drought, particularly in southeast Australia. Extensive areas of the southeast of the continent, including virtually all of Victoria and southern New South Wales, and much of the settled areas of South Australia had record low rainfall for the period of April 1982-February 1983.

It is generally agreed that the widespread bushfires that culminated in the enormous conflagrations of Ash Wednesday on 16 February 1983 were a direct consequence of the drought conditions.

Widespread heavy rains from March to May 1983 brought an end to the drought. Total losses were estimated in excess of $3000 million.

Physical Causes of Drought: The El Niño Factor

The physical causes of drought have their origins in the natural fluctuations of the global climate system, which is an extremely complex mix of different subsystems: the atmosphere, oceans, ice masses, and the biosphere, all interacting on a wide range of time and space scales. Given this high potential for internal variability, the significance or even the possibility of influences from sunspots, phases of the moon, and so on, remains highly questionable.

El Niño is linked to a swing in the mean atmospheric pressure difference across the Pacific Ocean called the Southern Oscillation. Many of the widespread and severe droughts affecting eastern and northern Australia were a direct consequence of a marked swing in the Southern Oscillation.

The Future

Droughts will continue to be a prominent feature of the Australian scene. However, improved meteorological drought-watch services and hopefully an improved ability to forecast droughts through local research and participation in the World Climate Programme, will help mitigate their adverse impacts.