While opinions remain divided in Australia about the effects of global warming, there can be little doubt that weather in Australia has become hotter and drier.
Australia's climate has warmed in both mean surface air temperature and surrounding sea surface temperature by around 1 °C since 1910 with the duration, frequency and intensity of extreme heat events increasing. May–July rainfall has reduced by around 19 per cent since 1970 in the southwest of Australia, and there has been a decline of around 11 per cent since the mid-1990s in the April–October growing season rainfall in the continental southeast.
May–July rainfall has reduced by around 19 per cent since 1970 in the southwest of Australia, and there has been a decline of around 11 per cent since the mid-1990s.
With such empirical data, it is little wonder scientists and businesses are seeking viable solutions to our water issues. We have already seen six desalination plants built across Australia between 2006 and 2012. Now, South East Water is also investigating the viability of a rainwater-trading scheme for Fisherman’s Bend in the inner south of Melbourne.
According to Matt Mollett of South East Water, “The rainwater micro-trading project is an early-stage research initiative looking at the different ways to support greater use of alternative water sources in high density developments, and reduce our reliance on precious drinking water supplies.” Research undertaken by Melbourne’s government-owned water corporations has found that demand for water could outstrip supply within 11 years (worst-case scenario) or within 25 years (based on moderate projections).
“With an increasing number of developments making use of recycled water and rainwater as well as drinking water, South East Water is exploring what alternative water use in developments such as Fishermans Bend might look like in the future, and how such use can be encouraged in the most efficient and equitable way,” Matt Mollett says.
The micro-trading scheme will operate in much the same way as solar energy rebates where households can reduce their power bill by selling power back to the grid. In a rainwater trading scenario, it is anticipated apartments in a block would be assigned a quota of free rainwater (captured in communal rooftop tanks). The water could then be used or traded to other residents, resulting in a bill reduction from South East Water.
The micro-trading scheme will operate in much the same way as solar energy rebates where households can reduce their power bill by selling power back to the grid.
The tanks would need to be drained by South East Water ahead of forecast downpours, to mitigate flooding risks to high-rise apartments, which creates some complications to be considered in the feasibility research.The tanks will automatically react to weather data supplied by the Bureau of Meteorology, and will supply water to a recycling plant owned by South East Water, scheduled for development in Fisherman’s Bend, to supply treated water for non-drinking usage.
It is anticipated a successful trading scheme could result in a reduction in mains water usage in Fisherman’s Bend of up to 45 per cent compared to other areas of Melbourne, with around 400 megalitres of rainwater being reused each year.
At this stage, the rainwater micro-trading concept has not been included on the Fisherman’s Bend Development plans, which include redevelopment of 490 hectares over 30 years, and resulting in 80,000 new residents. The development, located six kilometres from the CBD, is the result of the site being rezoned from industrial to urban.
"The rainwater micro-trading project seeks to explore whether or not these benefits could be transferred into a residential or urban context in the future.”
“Although Fishermans Bend provides a context for the research project, there are no plans in place to introduce rainwater micro-trading in the development, explains Matt Mollett. “Water trading is currently used for agricultural irrigation supplies, and enables under-utilised allocations to be potentially used for the benefit of other users, or the water network more broadly. The rainwater micro-trading project seeks to explore whether or not these benefits could be transferred into a residential or urban context in the future.”