ABSTRACT
This chapter explores certain themes which illustrate the distinctiveness of Australian rivers. Such themes include the origins and their more recent natural evolution, their geography, the nature of changes induced both naturally and by man in 200 years of European settlement, and denudation rates. The refinement of early ideas about Tertiary rivers in Eastern Australia has come about with the dating of widespread, fossilising basalt flows, the determination of fossil flow directions, and the use of other geological techniques. Three main stages of fluvial surface forms have been identified: prior streams, of 20 000 years of more, related to the last glacial stage; ancestral rivers of the Holocene; and the present channels. Hydrological regimes describe the amount and timing of water passing through river systems. A regular regime would exist where the timing and size of events were similar on the annual hydrograph (e.g. snowmelt regime), whereas a stable regime would show no progressive deviations over a period of years.
