Fallout from Australia’s Week Of Bushfires May Affect Victoria Water Supplies For 30 Years

22 February 2009

In Victoria, Australia, Melbourne Water managing director Robert Skinner has estimated that reservoirs supplying a quarter of the city’s water will be contaminated by fire-related runoff for at least three months, and that the water catchment basins which supply the city will see water inflows to some sources reduced by almost a third for the next three decades.

Dehydrated soils and burned forests around Melbourne Water reservoirs will draw more water than normal as they replenish in coming years, while increased sediment runoff around some reservoirs will reduce reservoir capacity. More than fifteen million cubic meters of water has been transferred from the Upper Yarra reservoir in an effort to avoid further contamination from the nearby Kinglake Complex fire, which continues to burn.

Melbourne’s water is stored in nine separate reservoirs, which helps protect supply during severe bushfires. However, years of drought have already reduced the city’s reserve supplies to a third of capacity. Melbourne Water has joined firefighters in an effort to protect the Upper Yarra and Thomson reservoirs, bulldozing and back-burning fire control lines.

In 2007, the Intergovernmental Panel on Climate Change (IPCC) found that an increase in fire danger in Australia would be likely to be associated with reduced interval between fires, increased fire intensity, a decrease in fire extinguishments and faster fire spread.  The IPCC’s projections, published in its Fourth Assessment Report, found that in southeast Australia, where this year’s bushfires occurred, the frequency of very high and extreme fire danger days was “likely to rise 4-25% by 2020 and 15-70% by 2050.”

Writing this week on the RealClimate website (link), David Karoly, a professor of meteorology at the University of Melbourne, noted that “while it is difficult to separate the influences of climate variability, climate change, and changes in fire management strategies on the observed increases in fire activity, it is clear that climate change is increasing the likelihood of environmental conditions associated with extreme fire danger in south-east Australia and a number of other parts of the world.”

Australia observed a Day of Mourning on 22 Feb for victims of the bushfires, most of who died on 7 February, now known as “Black Saturday.” The death toll so far stands at 209; burn areas are, however, being re-examined as some dwellings which had already been inspected by forensic teams have been found to have human remains which were not initially identified as such. More than 1,800 structures and 450,000 hectares (1,700 square miles) have been burned so far by the fires.