Australia’s water security part 1: water resources

This paper provides an overview of water availability in Australia, the major sources of water, and the spatial and time challenges limiting access to water resources. Summary Australia is recognised as the world’s driest inhabited continent; with access to just over one per cent of global freshwater resources. In addition, the variability in water availability across the continent is considerable. Despite limited freshwater resources, most Australians have ready access to water and one of the highest per capita usage rates in the world. This, however, does not reflect the variability in water access across the country. While rainfall in the tropical north is high for short periods of the year, the high demand areas in the south-east and south-west do not have access to that water. Groundwater, surface water and rainfall vary greatly from region to region and population growth and climate change are expected to make these disparities more pronounced. It is critical that the variability of Australia’s water resources is acknowledged; generalisations about the state of Australia’s water security nationally must be avoided, to ensure policy measures are designed for local conditions. Key points Despite occupying 5.6 per cent of the world’s landmass, Australia receives little more than one per cent of the world’s available freshwater resources. The bulk of Australia’s population, agriculture and industry are located in the temperate and southern coastal stretches of Australia, while more than 50 per cent of its water run-off occurs in tropical and sub-tropical northern Australia. Approximately 85 to 95 per cent of rainfall in Australia is lost to evaporation or transpiration. Only five to 10 per cent of Australia’s annual rainfall reaches streams, water storage or groundwater aquifers. Managing Australia’s water more efficiently and increasing its capture and storage will be critical to ensure ongoing water access under climate change and population growth predictions