Australia’s inland rivers are the pulse of the outback. By 2070, they’ll be unrecognisable



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Zacchary Larkin, Macquarie University; Stephen Tooth, Aberystwyth University, and Timothy J. Ralph, Macquarie University

Inland Australia’s complex system of winding rivers, extensive wetlands, ancient waterholes and seemingly endless parched floodplains are rarely given more than a passing thought by many Australians who live on the coastal fringes.

Yet these waterways are lifelines along which communities, agriculture and trade have flourished.

Etched into the psyche of regional Australia, these river systems are the pulse of the outback. Before asking a local how things are going, peek over the bridge in town for an indication.




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When relaxing in the shade of an old river red gum alongside one of Australia’s lazy inland rivers, it’s natural to think of them as timeless and resilient to environmental change.

Yet, these rivers evolved over millennia and continue to change over years and decades.

And we already know from previous studies that future climate change is likely to reduce stream flow and water availability in drylands around the world.

But what our new research has shown, for the first time, is that these declines in stream flow may trigger a dramatic change in the physical structure and function (the geomorphology) of Australia’s inland rivers.

The Macquarie River in dry (2008) and wet (2010) conditions.
Tim Ralph, Author provided

Meandering rivers and flat, wide floodplains

The physical structure of a river depends on how much water flows through it, and the sediment that water carries.

Reductions in water flow – as expected due to climate change – can lead to a build-up of sediment downstream. In extreme cases, this “silting up” can cause complete disintegration of river channels, where water flows out across the floodplain.

Not all rivers are alike, and the rivers of the Murray-Darling and Lake Eyre basins (covering 1.8 million square kilometres) are particularly diverse. Many of these rivers and wetlands are internationally recognised for their hydrological and ecological importance.




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They range from large meandering rivers swollen by seasonal spring flows (the Upper Murray, Mitta Mitta, Kiewa, and Ovens rivers), to rivers that progressively get smaller until they become exhausted on flat, wide floodplains and disintegrate into large, boom-and-bust wetlands (the Lachlan, Macquarie, and Gwydir rivers).

Dry channel of the lower Warrego River, northwest NSW.
Author provided

In the drier areas of central Australia, rivers typically persist as a string of isolated waterholes for years at a time, occasionally punctuated by very large floods (Warrego, Paroo, Diamantina, and Cooper Creek).

A sobering future

For Australia’s inland rivers, the average dryness, or “aridity”, of the catchment is the best predictor of what the overall structure and function of the rivers within look like.

Compiling a range of climatic data, we modelled aridity for the Australian continent in 2070 under a relatively moderate climate change scenario.

The results are sobering. Over the next 50 years, the arid zone – containing the areas of true desert – is projected to expand well into the Murray-Darling Basin and almost entirely envelope the Lake Eyre Basin.

Modern aridity index and the projected aridification of Australia by 2070. The red outlines show the extent of the Murray-Darling and Lake Eyre basins.

At the same time, the humid and dry subhumid fringes around the Great Dividing Range and coastal areas are expected to contract.

This is concerning because the relatively wet western slopes of the Great Dividing Range are where many inland Australian rivers begin, with most of their water sourced in these smaller sub-catchments.

Evolution of our inland rivers

The impact of this projected drying pattern on Australia’s inland rivers is expected to be profound.

Despite only occupying around 3.8% of the Murray-Darling Basin, the Upper Murray, Mitta Mitta, Kiewa, and Ovens rivers presently provide a large amount of flow within the lower Basin (33% of average annual flows).

These rivers flow out of the southeastern highlands towards the Murray River, but over the next 50 years they’re expected to experience declining downstream flows. This leads to less efficient flushing of sediment downstream, which, in turn, will increase sediment deposition within these rivers, reducing their size.

Channel breakdown along Eldee Creek in far western NSW.
Tim Ralph, Author provided

Other rivers – such as the Murrumbidgee and Macintyre rivers – are expected to undergo even more dramatic changes to their structure and behaviour.

Right now these rivers maintain a winding course to the central Murray and Barwon rivers, respectively. But our projections suggest these continuous channels won’t be supported, and are likely to be interrupted by sections of channel breakdown.

Under a drier climate, rivers such as the Lachlan and Macquarie may come to resemble present-day central Australian rivers – only persisting as disconnected waterholes for long periods of time, with internationally important wetlands (Great Cumbung Swamp and Macquarie Marshes) much less frequently inundated.




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Such changes to river structure and function will have long-lasting impacts on water, sediment, and nutrient distribution. This will likely change the dynamics of the river ecosystem, as well as the way we manage and use these rivers.

A parched future

While our research hasn’t investigated the potential ecological, socio-economic or cultural effects of structural changes, we can expect them to be very significant, and potentially irreversible.




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Many of Australia’s native aquatic and dryland flora and fauna are adapted to a highly variable climate regime, but there are limits beyond which these ecosystems cannot recover or survive. For example, seeds and invertebrate eggs can survive many years buried in dry soil waiting for a flood, but if water doesn’t come, eventually they won’t be viable.

Parched soil in the Macquarie Marshes, NSW.
Gavin Smith, Author provided

What’s more, extracting too much water from our inland river systems for agriculture or other uses will exacerbate the threats posed by a drying climate.

Given the complexity and tensions surrounding water use and water sharing in Australia’s inland rivers, particularly in the Murray-Darling Basin, understanding how these critical systems might respond in the future is now more important than ever.

Water is one of the most contested resources in Australia, and it’s the fundamentally important river and wetland ecosystems and agricultural industries that will bear the brunt of a drying climate.

To make sure outback communities can continue to survive, it’s vital we protect their lifeline. Water resource planning must include consideration of climate change, as the projected changes will likely increase pressure on already vulnerable systems.The Conversation

Zacchary Larkin, Postdoctoral Researcher in Environmental Sciences, Macquarie University; Stephen Tooth, Professor of Physical Geography, Aberystwyth University, and Timothy J. Ralph, Senior Lecturer in Environmental Sciences, Macquarie University

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

3 ways nature in the city can do you good, even in self-isolation



Lucy Taylor, Author provided

Lucy Taylor, University of Melbourne; Dieter Hochuli, University of Sydney, and Erin Leckey, University of Colorado Boulder

Spending time at the beach or taking a walk in the park can help us recover from the mental and physical impacts of life’s stresses. But physical distancing measures to contain COVID-19 have included closing beaches, playgrounds and parks, adding to the challenges to our mental health. When we stay home to flatten the curve, how can we help ourselves by taking advantage of the benefits associated with nature?

Public playgrounds have been closed to encourage distancing and limit infection.
Peter Lead, Author provided

The evidence for nature supporting human well-being has grown in recent decades. We researched the links between nature and urban residents’ well-being and found there are benefits of nature that we can still enjoy now, even in lockdown.
Our findings point to some of the ways we can improve our well-being by engaging with everyday nature close to home.




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1. A room with a view

We reviewed the evidence, collected survey data on self-reported well-being and biodiversity indicators, and organised focus groups in Sydney and Melbourne, Australia, and Auckland and Wellington, New Zealand, to better understand participants’ relationship with urban nature.

If you’re stuck at home, the good news is there is plenty of research that suggests a view through a window of vegetation or a body of water can provide a micro-break. A view of nature through a window has even aided hospital patients’ recovery from surgery. A short, 40-second glance at a green roof supports cognitive restoration better than a view of concrete.

Our research found urban residents had greater self-reported well-being when they had nature nearby or visible from their homes. Participants valued a view of vegetated areas – green space – and bodies of water – blue space. One participant said:

I could live in something that was pretty grim if it had a balcony that looked out [at nature].

Participants in our focus groups also highlighted the importance of seeing changes in the natural world, such as change in the weather or the seasons. Even if your view does not have a lot of vegetation or water, a view of the sky can allow engagement with nature’s dynamism.

A view out a window at nature’s dynamism can improve our well-being.
Lucy Taylor, Author provided



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2. Gardening – indoors and out

If you’re lucky enough to have a yard or balcony, now may be a good time to do some gardening. Gardening can offer benefits such as reductions in stress, anxiety and depression. As a physical activity, gardening can also improve physical fitness and support weight loss.

Gardens can also provide habitat for wildlife, potentially introducing you to new plants, pollinating insects and birds. Urban biodiversity benefits us too.

Our study found strong links between gardening and self-reported well-being. If you don’t have a yard, gardening on a balcony or tending to indoor plants also has benefits. One participant explained:

Having a small vegetable garden and flowers in pots makes me feel happy and content … It is wonderful to see things grow in the city.

Gardening in a yard, on a balcony, or even tending indoor plants does us good.
Peter Lead, Author provided



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3. Green exercise

We know exercise is good for physical fitness and mental health. “Green exercise”, or exercise that takes place in and around nature, can improve your mood and self-esteem.

Our study found strong links between how often urban residents exercised and their self-reported well-being. One participant described how important green exercise is to them:

Being able to walk my dog down at the beach or go up into the hills is a great stress relief and keeps me fit and healthy and, best of all, it’s free.

Another participant described exercising in a public park:

I feel significantly calmer, [my] breathing rate goes down. I love the feel of that moist air going into my lungs from all the trees and I really do feel different.

To limit infection, residents of cities around the world are subject to a range of national and local constraints on when and how they leave the house to exercise. It is important to follow physical distancing guidelines, but it is also important to exercise rather than be both isolated and sedentary.




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Urban nature now and for the future

Nature can support our well-being now, when we all could use the help, but we need to protect it. Climate change talks have been postponed because of the COVID-19 pandemic, but it is clear climate change has not stalled, even taking into account the effect of lockdown on emissions.

There are lasting ways to reduce our emissions and create low-carbon and cooler cities. And the earlier we act, the better the outcomes will be.

If you have a yard, planting trees might be a good lockdown activity now and will ultimately benefit your future.




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Taking time to notice nature – via a glance outside, tending plants in pots or gardens, or via green exercise – will improve your well-being. Appreciating nature and having access to it has never been so important.The Conversation

Appreciating urban nature has never been more important.
Lucy Taylor, Author provided

Lucy Taylor, Assistant Researcher, School of Ecosystem and Forest Sciences, University of Melbourne; Dieter Hochuli, Professor, School of Life and Environmental Sciences, University of Sydney, and Erin Leckey, Research Scientist, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder

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