In addition, higher temperatures will lead to higher rates of evaporation and
evapotranspiration, and therefore to increased demand for water for given levels
of crop production (Doll 2002). Water stress (the ratio of irrigation withdrawals
to renewable water resources) is likely to increase in many parts of the world
(Arnell 2004).
2. The Murray-Darling Basin
The Murray-Darling Basin is an area of national significance in Australia. The
Basin covers over 1 million km2 or 14 per cent of Australia’s land area
(Australian Bureau of Statistics 2008). The Basin contains the catchments of two
major rivers: the Darling and the Murray, along with many tributaries of which
the most significant is the Murrumbidgee. Most of the Basin is naturally semi-
arid (variable rainfall with average annual rainfall between 250 and 300
millimetres). Irrigation has played a major role in the expansion of agriculture
in the Basin since the late 19th century (Quiggin 2001).
Figure 1: Murray-Darling Basin, Australia