Our climate
The climate of the south-eastern region of Australia is highly variable. The region spans several different climate zones:
- cool, humid eastern uplands
- temperate south-eastern mallee
- inland sub-tropical northern areas
- hot, dry arid and semi arid country in the far west.
As well as the differences in climate between zones, large differences in temperature, rainfall and evaporation also occur within zones on a seasonal and annual basis, and over periods of several years. This variability is reflected in streamflow across the region, which has, historically, been subject to both extreme floods and droughts.
The River Murray system provides water to irrigators, communities and the natural environment in the southern part of the Murray–Darling Basin. Climate change is expected to result in changes to both average rainfalls and temperatures and in the frequency and severity of floods, droughts and fires. These changes are likely to have significant social, economic and environmental consequences.
The recent drought
Research in Phase 1 of SEACI found that the recent drought (1997 – 2009) was unprecendented compared with other droughts on record, being largely constrained to south-eastern Australia, having lower year-to-year rainfall variability and no 'wet years', and having a seasonal pattern of rainfall decline which was maximum in autumn.
The 11 percent reduction in rainfall in the southern Murray-Darling Basin over the period 1997-2009 compared with long-term averages led to a 44 percent reduction in assessed streamflow. This is significantly higher than in previously recorded droughts.