For green cities to become mainstream, we need to learn from local success stories and scale up



Melbourne has a rich legacy of urban parks thanks to planning decisions made when the city was first established.
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Jason Alexandra, RMIT University

Greening our cities has become one of the great global imperatives of the 21st century including to tackle climate change. And Australia’s sprawling car-based cities are gradually changing to embrace green or living infrastructure.

Green cities bring together elements of architectural design and urban planning, often combining plants and built infrastructure to meet the needs of humans, such as our love of nature.




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Trees, plants, waterways and wetlands can deliver climate conditioning, cooling cities by reducing the urban heat island effect. They also absorb carbon dioxide, filter wastewater and create habitats.

Living elements can be incorporated with built infrastructure at a range of scales, from individual buildings with green walls and roofs, through to citywide strategies. And there are a suite of strategies to guide more widespread integration of biological elements and ecological processes in cities.

In recent months, we profiled Australian examples of living infrastructure that show some of Australia’s approaches to developing green infrastructure, from greening Melbourne’s laneways to Canberra’s urban forest. These cities are already redesigning their water systems and implementing urban forest strategies to create green belts and protect and restore waterways.

Melbourne and Canberra provide some useful examples of the green cities movement, but to make it mainstream, these techniques need to be adopted widely through policies supporting more holistic and better integrated urban planning.

Why we need urban forests

Percival Alfred Yeoman was one of the first Australian pioneers of urban forestry. In 1971, he articulated a clear vision for enhancing cities with trees.




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Local governments in Adelaide, Brisbane, Melbourne and Sydney, are implementing his ideas, committing to ambitious increases in urban canopy cover. Their targets range from 25% to 40%.

This revived interest in urban forestry comes from its well documented potential for accelerating the transition to more climate adaptive cities.

The social, environmental and economic benefits of urban trees, or “ecosystem services”, are becoming better recognised, including for their recreational and cultural values.

Melbourne and Canberra are leading Australia’s green cities movement

Melbourne

Melbourne has a rich legacy of urban parks and green belts thanks to planning decisions made in the city’s early years.




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These parks underpin a new wave of urban greening, with projects that aim to deliver action on climate change, biodiversity and the health and well-being of communities.

The Melbourne green infrastructure plan includes:

  • a “growing green guide” that provides practical advice to community and business groups on planning, design and maintenance of green infrastructure

  • the greening laneways strategy, which builds on the commercial revitalisation of Melbourne’s laneways over three decades. Laneways with greening potential were mapped and demonstration project developed to display techniques for making them more vibrant green spaces for business, tourists and locals to enjoy

  • an urban forest strategy, with an overall target of 40% canopy cover by 2040. And 5 to 8 million trees will be planted over coming decades for the greater Melbourne metropolis.

Canberra

Canberra is often described as “a city within a landscape” and the “bush capital”. But its higher altitude, hot dry summers and cold winters bring a set of challenges for green infrastructure.

With more than 800,000 planted trees, Canberra is an urban forest. But these trees require special care and attention given they are ageing and suffering from a hotter, drier climate.




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Wildfire also represents a significant risk where urban and rural areas connect. This means Canberra needs urban forests that will cool the city in warmer months without also escalating wildfire risks.

The ACT Government has committed to action on climate change, legislating targets for 100% renewable electricity by 2020 and carbon neutrality (no net carbon emissions) by 2045.

With more than 800,000 trees, Canberra is an urban forest.
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Integrated approach needed to expand green cities

Greening cities requires a holistic approach – for instance, not leaving the health of waterways entirely to water engineers.

Greening cities is more than just a technical challenge. Transforming the form and functions of urban systems, through urban forests and other living infrastructure, requires greater leadership and political commitment, integrated planning and community participation, and long-term thinking.

An integrated approach to greening cities involves mapping diverse opportunities and mobilising support for change in the community. As an example, urban storm water can be a productive resource when used in constructed wetlands or to irrigate urban forests.

The vertical gardens in One Central Park in Sydney are globally renowned for their green infrastructure.
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And often urban drainage lines and wastelands can be transformed into green spaces, but it’s worth recognising there is intense competition for space for housing.

But for more widespread adoption of integration, institutional support within local governments and metropolitan water and planning agencies is needed.

So to scale up living infrastructure in our urban landscapes, we must learn from local success stories, conduct more research, and better understand how to deal with climate adaptation and mitigation challenges.




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Jason Alexandra would like to gratefully acknowledge the contributions of Barbara Norman to this article.The Conversation

Jason Alexandra, PhD candidate, RMIT University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Billions spent on Murray-Darling water infrastructure: here’s the result


Q J Wang, University of Melbourne and Avril Horne, University of Melbourne

Earlier this year, researchers suggested the amount of water returned to the Murray Darling Basin under a federal program has been “grossly exaggerated”, to the tune of hundreds of billions of litres.

The report argued that government investment in irrigation improvements might even result in a net loss of water for the environment.




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To investigate these claims, the Murray Darling Basin Authority commissioned us to undertake an independent review to examine the best available data for every irrigation efficiency project funded across the basin.

We found the government investment into irrigation efficiency projects has achieved 85% of the 750 gigalitres per year target. The remaining 15% of the target may be affected by unintended side-effects.

This result highlights the need for continued review of risks to the basin plan, as Australia grapples with the management of an extraordinary complex natural system.

How is water for the environment recovered?

The Water Act 2007 introduced significant reforms aimed at setting aside more water for the environment. At the time, record high levels of surface water were being consumed. Aiming to save 2,750 gigalitres of surface water (water flowing in the open air, rather than underground) the federal government began buying back water rights and investing in more efficient infrastructure.

The Commonwealth is providing A$3.1 billion to buy these water rights, of which A$2.5 billion has been spent. It is also providing more than A$8 billion for modernising infrastructure and water efficiency improvements, of which more than A$4 billion has so far been spent.

These projects aim to improve water delivery – reducing leaks and evaporation – and make irrigation more efficient. The water saving generated from these projects is shared between the governments for environmental use, and irrigators.

Mass fish deaths earlier in the year raised serious concerns about the health of the Murray-Darling system.
DEAN LEWINS/AAP

What are “return flows”?

To understand why the government investment in irrigation efficiency projects have not achieved 100% of the original target, we need to talk about return flows.

When water is diverted from the river for irrigation, not all of it gets consumed by the plants. Some water will make its way back to the river. This is called return flow. A large part of the return flow is through groundwater to the rivers, and this part is extremely difficult to measure. More efficient infrastructure and irrigation generally means less return flow to the river.

If these reductions are not considered when calculating the water savings, it is possible there will be implications for irrigators, the environment and other water users downstream, that previously benefited from return flows.

What we tried to determine is how much the efficiency projects reduced return flow.




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Are the water savings real?

For the first time, we attempted to bring together data on individual projects in order to assess return flows across the basin. We developed a framework for calculating return flows, which took into account water in the rivers, groundwater, and efficiency projects.

This is the first attempt to bring together the existing data on individual projects to assess return flows in the basin at a detailed level. A large portion of the data used in this study was collated for the first time and not previously available in a readily accessible format.

We found a reduction in return flow of 121 gigalitres per year as a result of the government funded projects. This is comparable to 16% of the recovery transferred to environmental entitlements.

What does this mean for the Basin Plan?

There are several important details that must be considered to assess the importance of the return flow volume for the environment and Basin Plan objectives. We do not attempt here to quantify the outcomes, but instead to raise a number of important considerations beyond simply “volume”.

1. Recovered water should be legally protected

Return flows are good for the environment, but are essentially accidental. As irrigation becomes more efficient, inevitably they will diminish.

On the other hand, formally allocated environmental water entitlements are legally protected. It is more secure for the environment – and far easier to keep track of.

2. It’s not ‘efficiency vs the environment’

Part of this debate centres around the idea that reducing return flows means less water for the environment. But in Victoria and New South Wales, before water is allocated to anyone (irrigators or the environment), a base level is set aside. This is the minimum required to keep the rivers physically flowing and to meet critical human needs.

Efficiency projects mainly affect this base-level flow of the river. This means the water reduction is shared across everyone who holds a water licence – the majority of which are irrigators.

This policy means it does not make sense to compare the effect of efficiency projects directly with the recovery of environmental water.

3. Volume is a crude measure of environmental benefit

The focus of the debate around return flows has been based on the annual volume of returned environmental water in comparison to the stated Basin Plan target.

However, the real objective of the water recovery is to achieve environmental objectives in the Basin. This is not just about annual volumes, but the quantity, timing, and quality of fresh water.

How should we move forward?

Our review has particularly highlighted the need for better ongoing data collection and regular evaluations.




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Both taxpayer investments and the water market are changing irrigation to become more efficient and reducing the river’s base flow. With this in mind, we need to regularly reexamine how we share water between everyone (and everything) that needs it, particularly in extended dry periods.

The Murray-Darling Basin is a constantly changing system, both in terms of climate and irrigation. Return flows are one of a number of potential threats to the Basin Plan. As the system is continually changing, these threats will need to be reassessed with each Basin Plan review.


A Four Corners program on the $13 billion Murray-Darling Basin Plan will air on ABC at 8.30pm on July 8.

This article was co-written by Glen Walker, a former CSIRO employee and now private consultant, who worked with the University of Melbourne on the independent review.The Conversation

Q J Wang, Professor, University of Melbourne and Avril Horne, Research fellow, Department of Infrastructure Engineering, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.