The development of an historical baseline of water balance and environmental flows

This paper has been motivated by a desire to put some numbers beside the label of sustainability as is currently applied to water related issues. Of particular interest is a general estimate of the water balance and environmental flows during the time intervals before Aboriginal arrival, when the land was being managed in an environmentally sustainable manner by the Aboriginals, and most recently following European settlement. This will be considered in an Australia-wide context, because the continent is geographically diverse, being mostly arid desert, with limited areas of fertile soils. Climate variation ranging from a hot tropical north to a cool temperate south will also be discussed. Attention will be given to the major factors that have influenced the water balance, including the extinction of Australian megafauna, the effects of "fire-stick" farming and the clearance of land for European agriculture with its consequences. It is hoped that the findings will increase our understanding of Australian water resources, and promote a greater appreciation of the fragility of this ancient landscape on which we dwell.