This content forms a part of our issue briefing on sustainable cities and communities.
SDG 11.7 By 2030, provide universal access to safe, inclusive and accessible, green and public spaces, in particular for women and children, older persons and persons with disabilities.
SoE 2016: Built environment: Related key finding: “Pressures from population growth are having a high and negative impact on aspects of the quality of the natural environment, as well as the liveability of Australia’s built environment.”
One advantage of the low-density suburban form that typifies Australian cities is its compatibility with high levels of urban greenspace coverage. However, levels of canopy cover (in the form of mature trees), green open space and other vegetation such as shrubs and gardens beds vary significantly both within and between Australian cities, irrespective of density.
A Benchmarking Report into Urban Canopy Coverage completed by the University of Technology Sydney, for example, found wide variations between Melbourne’s western and eastern suburbs, with the City of Maribyrnong having canopy coverage of only 7.4 per cent, while the City of Boroondara (an equivalent distance from the CBD to Melbourne’s east) had 28.1 per cent canopy cover.
Although urban municipalities are increasingly developing green-space strategies, these are largely focused on public land, despite the vast majority of urban land being privately owned; 84 per cent of the Melbourne metropolitan region, for instance. Modelling by Infrastructure Australia projects a decline in access to green space in Sydney and Melbourne over the next 30 years from 38 per cent and 62 per cent to 31–33 per cent and 54–58 per cent respectively, depending on different policy settings for urban growth.
New greenfield housing developments and infill sub-divisions are also limiting the potential for privately owned green space and large canopy trees, with an average Melbourne detached house built in 2007 covering 34.5 per cent of its allotment, compared to 21 per cent in 1990.
Analysis of greenfield developments in Perth suggested that “growth suburb” areas have shifted even more dramatically, from 32 per cent to 37 per cent in established areas to 56 per cent to 65 per cent in new developments.53 Critically, detached houses lead to less usable space than medium-and higher-density attached housing, which can maximise backyard or communal open space.
As such, although the SoE 2016 report posits green space as being pressured by population growth, the failure of private greening in both high- and low-density developments demonstrates that it is poor planning and regulation of recent developments, rather than population growth itself, that is leading to reductions in urban canopy coverage and biodiversity. As urban infill continues, new approaches to incentivising green space, and uptake of new approaches to greening high-density areas needs to be encouraged, drawing on policies from higher-density exemplars of urban greening such as Singapore.
In contrast with European and northern American green-space strategies, water availability defines both household and government decision-maker perceptions of the potential for — and difficulties in maintaining — urban green infrastructure. A major shift in Australian cities over the last decade has been the uptake of rainwater collection and greywater re-use, household water reuse having increased by 183 per cent between 2009/10 and 2015/16, while a quarter of all Australian households were using rainwater tanks in 2013, up from 19.3 per cent in 2007. Estimates of the total stormwater runoff from Melbourne (415GL) relative to overall water consumption (412GL) demonstrates the potential for effective stormwater management to play a significant role in flood reduction, potable water management and urban cooling through green infrastructure. Identifying similar co-benefits across other areas of sustainable urban design will be critical if Australia’s cities are to remain some of the world’s most liveable as they continue to grow in a changing climate.
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