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Key climatic events
State by State analysis
Changes in river systems
Key climatic events
A range of climatic events will play instrumental roles in shaping the changing nature of Australia's water systems under human-induced climate change. These include:
Despite forecasts for decreased rainfall in many areas of Australia, research by CSIRO (2004) predicts that by 2040, climate patterns for the eastern coast of Australia are likely to bring about more intense and more frequent extreme rainfall events. The most vulnerable regions for extreme rainfall include Coffs Harbour, Coolangatta, north of Brisbane, and over mountainous terrain (CSIRO 2004).
The combined impact of increasing sea level rise and extreme weather events are likely to result in an increasing occurrence and severity of flood surges (CSIRO 2003). Research shows that with a 20cm sea level rise, water levels would likely double with a 40 cm rise, and damage costs associated with flooding would increase by up to 50% (CSIRO 2003). Overall, it is now widely agreed that sea level rise will rise by 10-40cm by 2040 (CSIRO 2003).
Increases in the occurrence and severity of drought events is expected across eastern and southern Australia, with the most severe events occurring in northeastern and southeastern Australia. Trends in increased drought are already being experienced in southern parts of Australia, whereby the 2002 drought was recognised as being the most severe drought since 1950 (Karoly et al 2003). The 2002 drought is the first drought in Australia where the impact of human-induced climate change can be clearly observed (Karoly et al 2003).
With hotter temperatures exacerbating evaporation rates, all parts of Australia are predicted to experience a decrease in moisture availability. Research suggests that increased evaporation rates will occur throughout all seasons, with a 0 - 10% increase by 2030 and a 0 - 32% by 2070. The most vulnerable regions include the eastern highlands and Tasmania (Passey 2003). Adding to the impacts of reduced rainfall in many parts, higher evaporation rates will further diminish river flows, leading to greater reductions in water availability.
With the cyclone region expected to move further south, the progression of climate change is predicted to bring about an increase in the maximum intensity of tropical cyclones. Heavy rainfall, which is characteristic to cyclones, will also be intensified.
What to expect in different regions of Australia?
Whilst northern Australia can expect to receive longer and more intense Australian Monsoon, with increased stream flows, southern mainland Australia can expect reductions in stream flows due to intensified evaporation and reductions in rainfall (Pittock 2003).
In the north, trends have moved towards increasing rainfall over summer months in large parts of western, northern and central Australia from 1952 to 2002 (CSIRO 2004).
In the south, long-recognised trends towards drier conditions have been observed for south-west Western Australia, and southern Australia as a whole.
Overall, this means that greater water surplus is likely to be gained in northern Australia where human use is low, and water shortages will be experienced where human use is high. An exception is Tasmania, which is likely to receive an increase in rainfall and water supply (Pittock 2003).
For a State-by-State analysis of changes in rainfall, click on the regions below:
ACT | NSW | NT | QLD | SA | TAS | VIC | WA
What does this mean for Australia's river systems?
Widely varying outlooks for water flows in catchments have been predicted for southern Australia. In many places there may be likely increases or decreases in river flows depending upon the severity of climate change. Overall, it can be said that under expected climate change, Australia's rivers and catchments will experience decreases in water flow.
Murray-Darling Basin - Upper Murray and Lower Murray
Macquarie River catchment