Client: Smart Water Fund, representing Melbourne Water, City
West Water, Yarra Valley Water, South East Water and the Department
of Sustainability and Environment Melbourne is a rapidly growing
urban centre that has experienced the risks and changes associated
with climate variability, as an extended drought saw water supply
dam levels fall to approximately 25% capacity during 2009.
Since 2009, issues surrounding both current and future water
supplies and costs have become increasingly present in politics and
the media.
One response to the issue has been to explore the alternative
role water sources can play in diversifying Melbourne’s water
supply, to alleviate the impacts of climate variability and
population growth. Only 30% of Melbourne’s water demand is for
quality drinking water, therefore alternative water sources could
make a significant contribution to providing fit-for-purpose supply
options.
The aim of this project was to explore, cost and quantify the
opportunities for alternative water sources across Melbourne in a
strategic and systematic manner, taking into account the spatial
variability inherent in these opportunities. The study also scored
and ranked the alternative water for a range of social and
environmental factors.
Description
The alternative water atlas
analysed four alternative water sources – centralised wastewater
recycling, de-centralised wastewater recycling (sewer mining and
blackwater treatment plants), stormwater harvesting and rainwater
harvesting. The project began by considering the water demands that
these different sources could supply across the Melbourne region,
by quantifying and mapping the locations of substitutable demands
up to the year 2060.
Spatial analysis was then performed to identify potential
opportunities for each alternative water source, and a water supply
– demand balance undertaken to quantify the yield of the
alternative water opportunities. The cost of these opportunities
was then calculated and assessed via the Rapid Assessment Method
(RAM) developed for this project. The RAM was developed through a
stakeholder workshop and incorporated a number of factors, which
were indicators of the environmental and social costs and benefits
of the alternative water option. A key element involved the mapping
of sensitive environmental receptors that alternative water use
could impact, thereby enabling assessment of the spatial variation
of environmental costs and benefits of different options across the
landscape. As an example, where there are high value streams that
have been identified as requiring protection, rainwater or
stormwater harvesting opportunities upstream of these areas scored
more highly in the RAM. This is due to the harvesting potentially
protecting the stream from pollutants, which could also have the
potential to cause positive impact on the stream flow by reducing
peaky flows caused by urbanisation. This incorporation of the
spatial variability of environmental costs and benefits of schemes
was a successful component of this project.
The deliverables of the project were a series of maps, and
spatial datasets that allow the comparison of the opportunities for
different alternative water options at a locality scale, including
information about potential yields, reliabilities, costs and RAM
scores.
Outcomes
The spatial nature of this
project, both the analysis and the outcomes, were seen as a
particularly innovative and effective way of studying and
communicating the potential for alternative water projects.
The Alternative Water Atlas, in combination with the City Scale
Alternative Water Options study undertaken by GHD in tandem with
this project, directly contributed to Melbourne’s Water Supply
Demand Strategy (WSDS), and effectively demonstrated the potential
role for alternative water projects in Melbourne’s water cycle.
For more information please contact:
Katherine Williams
T: 61 3 8687 8778
E: Katherine
Williams