Mainland Australia is a round island: there is a large area of land in the interior, far from the ocean. Australia is also an exceptionally old and weathered place, and is therefore very flat, with low likelihood of orographic rainfall. It is the driest inhabited continent on Earth (see for example Wahlqvist, 2008). Surface freshwater is often an intermittent, rather than permanent, feature of the landscape, and indeed is scarce for significant periods of the year (see for example Chartres & Williams, 2006; Wahlqvist, 2008). And rivers - imagined, mapped and worked as reliable features - are often in reality 'chain-a-ponds', long knotted strings of deeper waterholes separated by shallow or dried-out reaches (see for example Eyles, 1977; Selby, 1981). On first seeing the Namoi River in New South Wales, Eric Rolls's wife, Joan, is mightily disappointed: 'Is that the river? ... It just looks like a muddy waterhole' (Rolls, 1974, p. 4). The riverbed may be a permanent feature, although also often indistinct, and flowing water may be transient. Rainfall patterns are unpredictable but evaporation rates and flow regimes reliably extreme. Open plains may transform into vast lakes overnight, while almost equally quickly a shining water-body may disappear into sand and salt. Such conditions challenged settlers and policy-makers alike.