Floodplains aren’t separate to a river — they’re an extension of it. It’s time to change how we connect with them


Melissa Parsons, University of New England and Martin Thoms, University of New EnglandDramatic scenes of flood damage to homes, infrastructure and livelihoods have been with us on the nightly news in recent weeks. Many will be feeling the pain for years to come, as they contend with property damage, financial catastrophe and trauma.

But what if, for a moment, we removed the humans and their structures from these tragic images — what would we see?

We would see a natural process of river expansion and contraction, of rivers doing exactly what they’re supposed to do from time to time. We’d see them exceeding what we humans have deemed to be their boundaries and depositing sediment across their floodplains. We’d see reproductive opportunities for fish, frogs, birds and trees. The floods would also enrich the soils. Floods can be catastrophic for humans, but they are a natural part of an ecosystem from which we benefit.

These scenes clearly depict the intersection of humans and nature, and it’s not working out well for either side.




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We must envision a new way of interacting with floodplains – these brilliant social-ecological systems that are not separate to rivers but rather part of the riverine landscape.

Humans can live on and with floodplains — but the way we do that has to change.

What is a floodplain?

Floodplains are relatively flat stretches of land located next to rivers. It helps to think of them as an extension of the river; it is natural and normal for a river to flood their adjacent plains.

Floodplains are composed of sediment the river has transported and then deposited, which makes them incredibly fertile. Flow and sediment regimes interacting over decades — or millennia — determine the physical and ecological character of floodplains, and the way they flood.

There are more than 15 generic floodplain types in Australia. Each harbours a unique set of evolutionary properties, physical features and ecosystems.

These influence the way floodwaters traverse floodplains, how long water remains on a floodplain, the velocity, turbulence and depth of floodwaters, and ecosystem responses to flooding. Floodplains are complex and highly variable.

Floodplains are also dynamic and ever-changing — and we should expect them to change even more in the coming years. Australian rivers have experienced regular periods of increased flood activity in the past 100 years.

And climate change is predicted to increase flood activity.




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5 ways the government can clean up the Murray-Darling Basin Plan


Humans benefit from floodplains

Floodplains are among the most productive ecosystems on the planet – they are biodiversity hotspots.

That’s in large part due to periodic flooding between different parts of a river-floodplain system; flooding is crucial to the function of floodplains. Without floods, these floodplains wouldn’t “work” — they would not be able to deliver the ecosystem services we benefit from. Those benefits include, but are not limited to:

  • food grown in these fertile soils
  • regulation of a balanced ecosystem
  • cultural heritage
  • transportation (as floodplains are easy to build roads on)
  • the supply of good quality drinking water
  • recreation.

The economic value of floodplain ecosystem services exceed US$25,681 per hectare. Roughly 25% of global terrestrial ecosystem services come from floodplains.

Humans are drawn to live on floodplains because of their productivity. In Australia, the floodplains of the Murray Darling Basin, heavily developed for agriculture, yield more than A$10 billion annually. These floodplain ecosystems provide an estimated A$187 billion per annum from their various ecosystem services.

However, the more we interrupt floodplain processes with development, the more we diminish the supply of ecosystem services.

The perils of living on floodplains

Putting the people back into the news footage reveals a social picture that is costly, traumatic and disruptive. The events of the past weeks have now brought into focus the perils of living on floodplains.

Humans have come up with ways to contend with this peril. Dams and levees. Land use planning. Building codes. Engineered floodscapes. Insurance. Emergency preparation systems and community engagement.

But if floodplains are a social-ecological system, where society gains great benefits but is also periodically placed at risk, which side should get the greatest policy attention? The humans or the ecosystem?

The answer is: both. But they also need to be better integrated.

Balancing the social with the ecological

Balancing the social and ecological aspects of floodplains requires a mindset change. We must combine community participation with research, resilience and adaptation to make long-term decisions about the future of these complex social-ecological systems.

If society wants to continue to derive the billions of dollars of benefits from floodplains, we need to ensure that flooding continues to occur on floodplains, and adapt to risk in imaginative and innovative ways that also protect the benefits.

Business as usual is not an option. The limitations of technocratic controls such as dams and levees should now be obvious. Time and time again, these have increased flood risk and failed to flood-proof the floodplain.

Rarely do such linear solutions solve complex problems in social-ecological systems. Linear solutions often exacerbate a problem or simply move it on to other parts of the system, creating social inequality, environmental decline and future risk.

The Australian government’s 2018 National Disaster Risk Reduction Framework sets the challenge to join up the built, social, economic and natural environments to address disaster risk in Australia.

Accepting the challenge requires a broader focus on balancing the social-ecological sides of Australia’s vast floodplains. Complexity, not linear thinking, must be embedded in the way we reimagine policy about floodplains and floods.

This requires transformative collaborations between government departments, researchers, business, and community stakeholders.


If this article has raised issues for you, or if you’re concerned about someone
you know, call Lifeline on 13 11 14. This story is part of a series The Conversation is running on the nexus between disaster, disadvantage and resilience. You can read the rest of the stories here.
The Conversation

Melissa Parsons, Senior Lecturer, Geography and Planning, University of New England and Martin Thoms, Professor of Physical Geography, University of New England

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

A brutal war and rivers poisoned with every rainfall: how one mine destroyed an island



Locals living downstream of the abandoned mine pan for gold in mine waste.
Matthew Allen, Author provided

Matthew G. Allen, The University of the South Pacific

This week, 156 people from the Autonomous Region of Bougainville, in Papua New Guinea, petitioned the Australian government to investigate Rio Tinto over a copper mine that devastated their homeland.

In 1988, disputes around the notorious Panguna mine sparked a lengthy civil war in Bougainville, leading to the deaths of up to 20,000 people. The war is long over and the mine has been closed for 30 years, but its brutal legacy continues.




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When I conducted research in Bougainville in 2015, I estimated the deposit of the mine’s waste rock (tailings) downstream from the mine to be at least a kilometre wide at its greatest point. Local residents informed me it was tens of metres deep in places.

I spent several nights in a large two-story house built entirely from a single tree dragged out of the tailings — dragged upright, with a tractor. Every new rainfall brought more tailings downstream and changed the course of the waterways, making life especially challenging for the hundreds of people who eke out a precarious existence panning the tailings for remnants of gold.

The petition has brought the plight of these communities back into the media, but calls for Rio Tinto to clean up its mess have been made for decades. Let’s examine what led to the ongoing crisis.

Triggering a civil war

The Panguna mine was developed in the 1960s, when PNG was still an Australian colony, and operated between 1972 and 1989. It was, at the time, one of the world’s largest copper and gold mines.

It was operated by Bougainville Copper Limited, a subsidiary of what is now Rio Tinto, until 2016 when Rio handed its shares to the governments of Bougainville and PNG.

When a large-scale mining project reaches the end of its commercial life, a comprehensive mine closure and rehabilitation plan is usually put in place.




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But Bougainville Copper simply abandoned the site in the face of a landowner rebellion. This was largely triggered by the mine’s environmental and social impacts, including disputes over the sharing of its economic benefits and the impacts of those benefits on predominantly cashless societies.

Following PNG security forces’ heavy-handed intervention — allegedly under strong political pressure from Bougainville Copper — the rebellion quickly escalated into a full-blown separatist conflict that eventually engulfed all parts of the province.

By the time the hostilities ended in 1997, thousands of Bougainvilleans had lost their lives, including from an air and sea blockade the PNG military had imposed, which prevented essential medical supplies reaching the island.

The mine’s gigantic footprint

The Panguna mine’s footprint was gigantic, stretching across the full breadth of the central part of the island.

The disposal of hundreds of millions of tonnes of tailings into the Kawerong-Jaba river system created enormous problems.

Rivers and streams became filled with silt and significantly widened. Water flows were blocked in many places, creating large areas of swampland and disrupting the livelihoods of hundreds of people in communities downstream of the mine. These communities used the rivers for drinking water and the adjacent lands for subsistence food gardening.

Several villages had to be relocated to make way for the mining operations, with around 200 households resettled between 1969 and 1989.

In the absence of any sort of mine closure or “mothballing” arrangements, the environmental and socio-economic impacts of the Panguna mine have only been compounded.

Since the end of mining activities 30 years ago, tailings have continued to move down the rivers and the waterways have never been treated for suspected chemical contamination.




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Long-suffering communities

The 156 complainants live in communities around and downstream of the mine. Many are from the long-suffering village of Dapera.

In 1975, the people of Dapera were relocated to make way for mining activities. Today, it’s in the immediate vicinity of the abandoned mine pit. As one woman from Dapera told me in 2015:

I have travelled all over Bougainville, and I can say that they [in Dapera] are the poorest of the poor.

They, and others, sent the complaint to the Australian OECD National Contact Point after lodging it with Melbourne’s Human Rights Law Centre.

The complainants say by not ensuring its operations didn’t infringe on the local people’s human rights, Rio Tinto breached OECD guidelines for multinational enterprises.

The Conversation contacted Rio Tinto for comment. A spokesperson said:

We believe the 2016 arrangement provided a platform for the Autonomous Bougainville Government (ABG) and PNG to work together on future options for the resource with all stakeholders.

While it is our belief that from 1990 to 2016 no Rio Tinto personnel had access to the mine site due to on-going security concerns, we are aware of the deterioration of mining infrastructure at the site and surrounding areas, and claims of resulting adverse environmental and social, including human rights, impacts.

We are ready to enter into discussions with the communities that have filed the complaint, along with other relevant parties such as BCL and the governments of ABG and PNG.

A long time coming

This week’s petition comes after a long succession of calls for Rio Tinto to be held to account for the Panguna mine’s legacies and the resulting conflict.

A recent example is when, after Rio Tinto divested from Bougainville Copper in 2016, former Bougainville President John Momis said Rio must take full responsibility for an environmental clean-up.

And in an unsuccessful class action, launched by Bougainvilleans in the United States in 2000, Rio was accused of collaborating with the PNG state to commit human rights abuses during the conflict and was also sued for environmental damages. The case ultimately foundered on jurisdictional grounds.

Two people, one waist-deep in tailings.
Hundreds of millions of tonnes of tailings were deposited in the rivers.
Matthew Allen, Author provided

Taking social responsibility

This highlights the enormous challenges in seeking redress from mining companies for their operations in foreign jurisdictions, and, in this case, for “historical” impacts.

The colonial-era approach to mining when Panguna was developed in the 1960s stands in stark contrast to the corporate social responsibility paradigm supposedly governing the global mining industry today.




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Indeed, Panguna — along with the socially and environmentally disastrous Ok Tedi mine in the western highlands of PNG — are widely credited with forcing the industry to reassess its “social license to operate”.

It’s clear the time has come for Rio to finally take responsibility for cleaning up the mess on Bougainville.The Conversation

Matthew G. Allen, Professor of Development Studies, The University of the South Pacific

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

New Zealand government ignores expert advice in its plan to improve water quality in rivers and lakes



Tracey McNamara/Shutterstock

Michael (Mike) Joy, Te Herenga Waka — Victoria University of Wellington

New Zealand’s government has been praised for listening to health experts in its pandemic response, but when it comes to dealing with pollution of the country’s waterways, scientific advice seems less important.

Today, the government released a long-awaited NZ$700 million package to address freshwater pollution. The new rules include higher standards around cleanliness of swimming spots, set controls for some farming practices and how much synthetic fertiliser is used, and require mandatory and enforceable farm environment plans.

But the package is flawed. It does not include any measurable limits on key nutrients (such as nitrogen and phosphorus) and the rules’ implementation is left to regional authorities. Over the 30 years they have been managing the environment, the health of lakes and rivers has continued to decline.

For full disclosure, I was part of the 18-person science technical advisory group that made the recommendations. Despite more than a year of consultation and evidence-based science, the government has deferred or ignored our advice on introducing measurable limits on nitrogen and phosphorus.




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Polluted, drained, and drying out: new warnings on New Zealand’s rivers and lakes


Waterways in decline

The declining state of rivers, lakes and wetlands was the most important environmental issue for 80% of New Zealanders in a recent survey. It was also an election issue in 2017, so there was a clear mandate for significant change.

But despite years of work from government appointed expert panels, including the technical advisory group I was part of, the Māori freshwater forum Kahui Wai Māori and the Freshwater Leaders groups, crucial advice was ignored.

The technical advisory group, supported by research, was unequivocal that specific nitrogen and phosphorus limits are necessary to protect the quality of people’s drinking water and the ecological health of waterways.

The proposed nutrient limits were key to achieving real change, and far from being extreme, would have brought New Zealand into line with the rest of the world. For example, in China, the limit for nitrogen in rivers is 1 milligram per litre – the same limit as our technical advisory group recommended. In New Zealand, 85% of waterways in pasture catchments (which make up half of the country’s waterways, if measured by length) now exceed nitrate limit guidelines.

Instead, Minister for the Environment David Parker decided to postpone this discussion by another year – meaning New Zealand will continue to lag other nations in having clear, enforceable nutrient limits.

This delay will inevitably result in a continued decline of water quality, with a corresponding decline in a suite of ecological, cultural, social and economic values a healthy environment could support.




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The government’s package includes a cap on the use of nitrogen fertiliser.
Alexey Stiop/Shutterstock

Capping use of nitrogen fertiliser

The other main policy the expert panels pushed for was a cap on the use of nitrogen fertiliser. This was indeed part of the announcement, which is a positive and important step forward. But the cap is set at 190kg per hectare per year, which is too high. This is like telling someone they should reduce smoking from three to two and a half packets a day to be healthier.

I believe claims from the dairy industry that the tightening of environmental standards for freshwater would threaten New Zealand’s economic recovery are exaggerated. They also ignore the fact clean water and a healthy environment provide the foundation for our current and future economic well-being.

And they fly in the face of modelling by the Ministry for the Environment, which shows implementation of freshwater reforms would save NZ$3.8 billion.

Excess nitrogen is not just an issue for ecosystem health. Nitrate (which forms when nitrogen combines with oxygen) in drinking water has been linked to colon cancer, which is disproportionately high in many parts of New Zealand.

The New Zealand College of Public Health Medicine and the Hawkes Bay district health board both made submissions calling for a nitrate limit in rivers and aquifers to protect people’s health – at the same level the technical advisory group recommended to protect ecosystems.




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Our dependence on synthetic nitrogen fertiliser is unsustainable, and it is adding to New Zealand’s greenhouse gas footprint through nitrous oxide emissions. There is growing evidence farmers can make more profit by reducing their use of artificial fertilisers.

Continued use will only further degrade soils across productive landscapes and reduce the farming sector’s resilience in a changing climate.

The irony is that for a century, New Zealand produced milk without synthetic nitrogen fertiliser. Instead, farmers grew clover which converts nitrogen from the air. If we want to strive for better water quality for future generations, we need to front up to the unsustainable use of artificial fertiliser and seek more regenerative farming practices.The Conversation

Michael (Mike) Joy, Senior Researcher; Institute for Governance and Policy Studies, Te Herenga Waka — Victoria University of Wellington

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

Snowy 2.0 threatens to pollute our rivers and wipe out native fish



Schopier/Wikimedia

John Harris, UNSW and Mark Lintermans, University of Canberra

The federal government’s Snowy 2.0 energy venture is controversial for many reasons, but one has largely escaped public attention. The project threatens to devastate aquatic life by introducing predators and polluting important rivers. It may even push one fish species to extinction.

The environmental impact statement for the taxpayer-funded project is almost 10,000 pages long. Yet it fails to resolve critical problems, and in one case seeks legal exemptions to enable Snowy 2.0 to wreak environmental damage.

The New South Wales government is soon expected to grant the project environmental approval. This process should be suspended, and independent experts should urgently review the project’s environmental credentials.

Native fish extinctions

Snowy Hydro Limited, a Commonwealth-owned corporation, is behind the Snowy 2.0 project in the Kosciuszko National Park in southern NSW. It involves building a giant tunnel to connect two water storages – the Tantangara and Talbingo reservoirs. By extension, the project will also connect the rivers and creeks connected to these reservoirs.

A small, critically endangered native fish, the stocky galaxias, lives in a creek upstream of Tantangara. This is the last known population of the species.




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An invasive native fish, the climbing galaxias, lives in the Talbingo reservoir (it was introduced from coastal streams when the original Snowy project was built). Water pumped from Talbingo will likely transfer this fish to Tantangara.

From here, the climbing galaxias’ capacity to climb wet vertical surfaces would enable it to reach upstream creeks and compete for food with, and prey on, stocky galaxias – probably pushing it into extinction.

The stocky galaxias.
Hugh Allan

Snowy Hydro has applied for an exemption under NSW biosecurity legislation to permit the transfer of the climbing galaxias and two other fish species: the alien, noxious redfin perch and eastern gambusia.

Redfin perch compete for food with other species and produce many offspring. They are voracious, carnivorous predators, known to prey on smaller fish.

Redfin perch also allow the establishment of a fatal fish disease – epizootic haematopoietic necrosis virus – or EHN. This disease kills the endangered native Macquarie perch, the population of which below Tantangara is one of very few remaining.

If Snowy 2.0 is granted approval, it is likely to spread these problematic species through the headwaters of the Murrumbidgee, Snowy and Murray rivers.

The climbing galaxias, which threatens the native stocky galaxias.
Stella McQueen/Wikimedia

Acid and asbestos pollution

Four million tonnes of rock excavated to build Snowy 2.0 would be dumped into the two reservoirs. Snowy Hydro has not assessed the pollution risks this creates. The rock will contain potential acid-forming minerals and a form of asbestos, which threaten to pollute water storages and rivers downstream.

When the first stage of the Snowy Hydro project was built, comparable rocks were dumped in the Tooma River catchment. Research in 2006 suggested the dump was associated with eradication of almost all fish from the Tooma River downstream after rainfall.




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Addressing the problems

The environmental impact statement either ignores, or pays inadequate attention to, these environmental problems.

For example, installing large-scale screens at water inlets would be the best way to prevent fish transfer from Talbingo Dam, but Snowy Hydro has dismissed it as too costly.

Snowy Hydro instead proposes a dubious second-rate measure: screens to filter pumped flows leaving Tantangara reservoir, and building a barrier in the stream below the stocky galaxias habitat.

The best and cheapest way to prevent damage from alien species is stopping the populations from establishing. Trying to control or eradicate pest species once they’re established is far more difficult and costly.



The Conversation, CC BY-ND

We believe the measures proposed by Snowy Hydro are impractical. It would be very difficult to maintain a screen fine and large enough to prevent fish eggs and larvae moving out of Tantangara reservoir and such screens would be totally ineffective at preventing the spread of EHN virus.

A six metre-high waterfall downstream of the stocky galaxias habitat currently protects the critically endangered species from other invasive species threats. But climbing galaxias have an extraordinary ability to ascend wet surfaces. They would easily climb the waterfall, and possibly the proposed creek barrier as well.

Such an engineered barrier has never been constructed in Australia. We are informed that in New Zealand, the barriers have not been fully effective and often require design adjustments.




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Even if the barrier protected the stocky galaxias at this location, efforts to establish populations in other unprotected regional streams would be severely hampered by the spread of climbing galaxias.

Preventing redfin and EHN from entering the Murrumbidgee River downstream of Tantangara depends on the reservoir never spilling. The reservoir has spilled twice since construction in the 1960s, and would operate at much higher water levels when Snowy 2.0 was operating. Despite this, Snowy Hydro says it has “high confidence in being able to avoid spill”.

If dumped spoil pollutes the two reservoirs and Murrumbidgee and Tumut rivers, this would also have potentially profound ecological impacts. These have not been critically assessed, nor effective prevention methods identified.

The Tumut 3 scheme, part of the existing Snowy Hydro scheme.
Snowy Hydro Ltd

Looking to the future

Snowy 2.0 will likely make one critically endangered species extinct and threaten an important remaining population of another, as well as pollute freshwater habitats. As others have noted, the project is also questionable on other environmental and economic grounds.

These potential failures underscore the need to immediately halt Snowy 2.0, and subject it to independent expert scrutiny.


In response to the issues raised in this article, a spokesperson for Snowy Hydro said:

“Snowy Hydro’s EIS, supported by numerous reports from independent scientific experts, extensively address potential water quality and fish transfer impacts and the risk mitigation measures to be put in place. As the EIS is currently being assessed by the NSW Government we have no further comment.”


A previous version of this article incorrectly stated that water pumped from Tantangara will likely transfer fish to Talbingo. It should have said water pumped from Talbingo will likely transfer fish to Tantangara.The Conversation

John Harris, Adjunct Associate Professor, Centre for Ecosystem Science, UNSW and Mark Lintermans, Associate professor, University of Canberra

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

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.

Polluted, drained, and drying out: new warnings on New Zealand’s rivers and lakes



Shutterstock

Troy Baisden, University of Waikato

The latest environmental report on New Zealand’s lakes and rivers reiterates bleak news about the state of freshwater ecosystems, and warns that climate change will exacerbate existing threats.

Almost all New Zealand rivers running through urban and farming areas (95-99%) carry pollution above water quality guidelines, while most of the nation’s wetlands (90%) have been drained, and many freshwater fish species (76%) are threatened or at risk.

The most significant pressures on freshwater ecosystems fit into four issues:


Ministry for the Environment/Stats NZ, CC BY-SA

Climate change gets more attention than in earlier assessments, reflecting the fact that glaciers are already shrinking and soils are drying out.




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What whitebait tell us about freshwater fish under stress

The latest assessment is an update on a freshwater report in 2017 and the comprehensive Environment Aotearoa 2019. It reiterates issues we’ve seen before, but begins to implement recent recommendations by the Parliamentary Commissioner for the Environment (PCE) calling for a stronger link between data and environmental management.

Biological impacts are at the forefront of this latest assessment. It shows that a wide range of freshwater organisms are at risk. The statistics for freshwater fish are the most concerning, with three quarters of the 51 native species already either threatened or at risk of extinction.

The report uses a particular group of native fish (īnanga, or galaxids) to connect the multiple impacts humans have, across a range of habitats at different life stages.

Īnanga are better known as whitebait, a delicacy that is a mix of juveniles from six different species caught as they migrate from the sea to rivers.

Whitebait is considered a delicacy in New Zealand.
Shutterstock

Īnanga of different ages and species live in different habitats, so they can be used to represent the issues facing a range of freshwater fish across ecosystems. The main stress factors include altered habitat, pollution and excess nutrients, water use for irrigation and climate change.

Climate change is expected to exacerbate existing stresses native organisms like īnanga face and protecting their habitat means understanding how much it will reduce water flows and create hotter and drier conditions.

Filling gaps in understanding

The use of organisms to assess environmental change, including climate change impacts, is an obvious but important step. It makes it possible to consider climate change in a way that meets the Environmental Reporting Act’s requirement to report on a “body of evidence”.

This latest report responds to the PCE’s concerns about gaps in our knowledge, which were raised in the Environment Aotearoa 2019 assessment. The new strategy for filling large holes in our knowledge has three priorities: knowing and monitoring what we have, what we may lose, and where or how we can make changes.




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Six ways to improve water quality in New Zealand’s lakes and rivers


The report highlights that mātauranga Māori, the process of using indigenous knowledge about the environment, can fill some gaps in data or add insights. Other methods and models, such as nutrient budget scenarios, also deserve consideration.

There is some good news as well. Some pollution concerns may be minor or limited to very small areas. This includes several so-called emerging contaminants, such as fire retardants, which have been discovered in groundwater around airfields but are now banned or restricted.

The second piece of good news is that new ways of studying the environment can help fill major gaps. For example, lakes may be more stable indicators of freshwater health than rivers and streams, but only 4% (about 150) of New Zealand’s 3,820 larger lakes are regularly monitored by regional councils.

For almost 300 lakes, the report includes an index of the plants that live in them, and for more than 3000 there is now an established method of estimating lake water quality. Further information is becoming available, using updated estimations, satellite data for the last 20 years and sediment cores to reconstruct environmental conditions over the last few hundred years.

Unfortunately, the data from lakes confirms the general trend of freshwater decline, but at least the multiple forms of complementary information should help us to manage New Zealand’s freshwater ecosystems better.The Conversation

Troy Baisden, Professor and Chair in Lake and Freshwater Sciences, University of Waikato

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

The sweet relief of rain after bushfires threatens disaster for our rivers



After heavy rainfall, debris could wash into our waterways and threaten fish, water bugs, and other aquatic species.
Jarod Lyon, Author provided

Paul McInerney, CSIRO; Gavin Rees, CSIRO, and Klaus Joehnk, CSIRO

When heavy rainfall eventually extinguishes the flames ravaging south-east Australia, another ecological threat will arise. Sediment, ash and debris washing into our waterways, particularly in the Murray-Darling Basin, may decimate aquatic life.

We’ve seen this before. Following 2003 bushfires in Victoria’s alpine region, water filled with sediment and debris (known as sediment slugs) flowed into rivers and lakes, heavily reducing fish populations. We’ll likely see it again after this season’s bushfire emergency.




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Large areas of northeast Victoria have been burnt. While this region accounts only for 2% of Murray-Darling Basin’s entire land area, water flowing in from northeast Victorian streams (also known as in-flow) contributes 38% of overall in-flows into the Murray-Darling Basin.

Fire debris flowing into Murray-Darling Basin will exacerbate the risk of fish and other aquatic life dying en masse as witnessed in previous years..

What will flow into waterways?

Generally, bushfire ash comprises organic carbon and inorganic elements such as nitrogen, phosphorous and metals such as copper, mercury and zinc.

Sediment rushing into waterways can also contain large amounts of soil, since fire has consumed the vegetation that once bound the soil together and prevented erosion.

And carcinogenic chemicals – found in soil and ash in higher amounts following bushfires – can contaminate streams and reservoirs over the first year after the fire.

A 2014 post-fire flood in a Californian stream.

How they harm aquatic life

Immediately following the bushfires, we expect to see an increase in streamflow when it rains, because burnt soil repels, not absorbs, water.

When vast amounts of carbon are present in a waterway, such as when carbon-loaded sediments and debris wash in, bacteria rapidly consumes the water’s oxygen. The remaining oxygen levels can fall below what most invertebrates and fish can tolerate.

These high sediment loads can also suffocate aquatic animals with a fine layer of silt which coats their gills and other breathing structures.

Habitats are also at risk. When sediment is suspended in the river and light can’t penetrate, suitable fish habitat is diminished. The murkier water also means there’s less opportunity for aquatic plants and algae to photosynthesise (turn sunshine to energy).




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What’s more, many of Australia’s waterbugs, the keystone of river food webs, need pools with litter and debris for cover. They rely on slime on the surface of rocks and snags that contain algae, fungi and bacteria for food.

But heavy rain following fire can lead to pools and the spaces between cobbles to fill with silt, causing the waterbugs to starve and lose their homes.

This is bad news for fish too. Any bug-eating fish that manage to avoid dying from a lack of oxygen can be faced with an immediate food shortage.

Many fish were killed in Ovens River after the 2003 bushfires from sediment slugs.
Arthur Rylah Institute, Author provided

We saw this in 2003 after the sediment slug penetrated the Ovens River in the north east Murray catchment. Researchers observed dead fish, stressed fish gulping at the water surface and freshwater crayfish walking out of the stream.

Long-term damage

Bushfires can increase the amount of nutrients in streams 100 fold. The effects can persist for several years before nutrient levels return to pre-fire conditions.

More nutrients in the water might sound like a good thing, but when there’s too much (especially nitrogen and phosphorous), coupled with warm temperatures, they can lead to excessive growth of blue-green algae. This algae can be toxic to both people and animals and often closes down recreational waters.




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Strength from perpetual grief: how Aboriginal people experience the bushfire crisis


Large parts of the upper Murray River catchment above Lake Hume has burnt, risking increases to nutrient loads within the lake and causing blue-green algae blooms which may flow downstream. This can impact communities from Albury all the way to the mouth of the Murray River in South Australia.

Some aquatic species are already teetering on the edge of their preferred temperature as stream temperatures rise from climate change. In places where bushfires have burnt all the way to the stream edge, decimating vegetation that provided shade, there’ll be less resistance to temperature changes, and fewer cold places for aquatic life to hide.

Cooler hide-outs are particularly important for popular angling species such as trout, which are highly sensitive to increased water temperature.

Ash blanketing the forest floor can end up in waterways when it rains.
Tarmo Raadik

But while we can expect an increase in stream flow from water-repellent burnt soil, we know from previous bushfires that, in the long-term, stream flow will drop.

This is because in the upper catchments, regenerating younger forests use more water than the older forests they replace from evapotranspiration (when plants release water vapour into the surrounding atmosphere, and evaporation from the surrounding land surface).

It’s particularly troubling for the Murray-Darling Basin, where large areas are already enduring ongoing drought. Bushfires may exacerbate existing dry conditions.

So what can we do?

We need to act as soon as possible. Understandably, priorities lie in removing the immediate and ongoing bushfire threat. But following that, we must improve sediment and erosion control to prevent debris being washed into water bodies in fire-affected areas.




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In fact, there’s plenty we can do to make future fires less likely


One of the first things we can do is to restore areas used for bushfire control lines and minimise the movement of soil along access tracks used for bushfire suppression. This can be achieved using sediment barriers and other erosion control measures in high risk areas.

Longer-term, we can re-establish vegetation along waterways to help buffer temperature extremes and sediment loads entering streams.

It’s also important to introduce strategic water quality monitoring programs that incorporate real-time sensing technology, providing an early warning system for poor water quality. This can help guide the management of our rivers and reservoirs in the years to come.

While our current focus is on putting the fires out, as it should be, it’s important to start thinking about the future and how to protect our waterways. Because inevitably, it will rain again.The Conversation

Paul McInerney, Research scientist, CSIRO; Gavin Rees, , CSIRO, and Klaus Joehnk, Senior research scientist, CSIRO

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

New Zealand launches plan to revive the health of lakes and rivers



After years of delay, the New Zealand government is pushing ahead on a national plan to clean up the nation’s lakes, rivers and wetlands.
from http://www.shutterstock.com, CC BY-ND

Troy Baisden, University of Waikato

New Zealand’s government released a plan to reverse the decline of iconic lakes and rivers this week. It proposes higher standards for water quality, interim controls on land intensification and a higher bar on ecosystem health.

Freshwater quality was a significant election issue in 2017 and the proposal follows the recent release of Environment Aotearoa 2019, which links agriculture to freshwater degradation.

The agenda for change recognises that the perceived trade-off between agriculture and the environment makes little sense. If New Zealand trades internationally on a reputation for a healthy environment, continued degradation of water fouls the value of major exports. It also spoils the natural heritage that fuels the tourist economy and many New Zealanders consider a birthright.




Read more:
Six ways to improve water quality in New Zealand’s lakes and rivers


What’s changed?

The policy announcement reflects more than a decade of previous attempts, with the first draft notified in 2008, the first implementation in 2011, and major updates in 2014 and 2017. The new policy package addresses major deficiencies in the earlier versions, and has been fast-tracked to curtail freshwater pollution that has been allowed to get worse longer than it should.

The new regulations are designed to protect the health of entire ecosystems from excess nutrients. Some of the most compelling provisions draw clear lines where limits need to be set to prevent further slippage.

There’s a halt to significant expansions of dairy farming and irrigation, and limits on the use of nitrogen in some key catchments. Further improvements will better protect waterways and wetlands from grazing animals, and limits will be placed on recently criticised winter grazing.




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Two significant steps will reverse the main cause of delays in the past. The first is an implementation at national level. This should reduce reliance on a National Policy Statement (NPS) that requires regional councils to implement changes to local legislation.

This step will be reinforced by signalled changes to the national legislation, the Resource Management Act, which in turn will make regional council actions less cumbersome and underfunded. Secondly, where the new NPS requires region-by-region action, caps on increasing agricultural intensity will apply until regional plans have been amended to comply.

These steps increase the chance of preventing further degradation. Some benefits, such as a reduced risk of getting sick from swimming, should come through quickly. Others, such as reduced nutrient loads of nitrogen and phosphorous and a healthier ecology in lakes and rivers, could take years or decades.

Challenges ahead

To improve freshwater quality, we will need reliable monitoring and modelling tools to measure progress. These will need to be an integral part of the process, even though any decisions are ultimately determined by values. Working through this challenge highlights two large issues that remain unresolved in the plan.

The first is a lack of monitoring tools. The announcement didn’t take up recommendations in the Freshwater Leaders Group’s report that described present tools as unsuitable for providing enough confidence to move forward. The implications are that promised investment to develop the nutrient-monitoring Overseer tool will only eventually get us what we needed years ago.

Tools need to connect nutrient management with farm and catchment planning. They should focus more on future solutions rather than quantifying impacts of past land use that led to freshwater pollution.

The role for Māori

The issue of water allocation is even more important given the constitutional role Māori play in New Zealand’s freshwater governance, enshrined in the Treaty of Waitangi.

One of the most intriguing options left open to consultation is the extent to which Māori values will receive compulsory consideration, or alternately, be afforded consideration place-by-place by individual iwi (tribes) and hapū (sub-tribes). The advisory body representing Māori interests in the environment and in land-based industries raised concerns that these options are too weak.

These concerns are substantially amplified by the recent report by the Waitangi Tribunal, suggesting that the delays and dysfunction associated with freshwater policies have disproportionately undermined the ability of Māori to maintain holistic cultural connections to water, and obtain fair value from lands recently returned to them by the Crown.

These concerns and the need for better planning tools that resolve past degradation and enable future investment ultimately go hand-in-hand. Māori businesses, enabled by treaty settlements, are leading innovators and investors using social and environmental values to drive high-value exports.

The release now opens a period of consultation and national debate. This will pit the passionate voice of the farming community against voices representing our freshwater ecosystems. But this is the first time a proposed plan brings together all aspects of policy we need to keep aquatic life healthy.The Conversation

Troy Baisden, Professor and Chair in Lake and Freshwater Sciences, University of Waikato

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

Six ways to improve water quality in New Zealand’s lakes and rivers


File 20180416 566 16cxzx5.jpg?ixlib=rb 1.1
Lake Tarawera, seen from its outlet, has excellent but declining water quality.
Troy Baisden, CC BY-SA

Troy Baisden, University of Waikato

Two years ago, New Zealanders were shocked when contaminated drinking water sickened more than 5,000 people in the small town of Havelock North, with a population of 14,000. A government inquiry found that sheep faeces were the likely source of bacterial pathogens, which entered an aquifer when heavy rain flooded surrounding farmland.

A second phase of the inquiry identified six principles of international drinking water security that had been bypassed. Had they been followed, the drinking water contamination would have been prevented or greatly reduced.

Here, I ask if the approach recommended by the Havelock North inquiry to prevent drinking water contamination can be extended to reduce the impacts of nutrient contamination of freshwater ecosystems.




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Freshwater degraded and in decline

Most measures of the ecological health and recreational value of New Zealand’s lowland rivers and lakes have been rated as degraded and still declining. Intensive agriculture often cops much of the blame, but primary industry exports remain the heart of New Zealand’s economy.

The challenge posed by this trade-off between the economy and the environment has been described as both enormous, and complex. Yet it is a challenge that New Zealand’s government aims to tackle, and continues to rate as a top public concern.

An important lesson from the Havelock North inquiry is that sometimes there is no recipe – no easy list of steps or rules we can take to work through a problem. Following existing rules resulted in a public health disaster. Instead, practitioners need to follow principles, and be mindful that rules can have exceptions.

For freshwater, New Zealand has a similar problem with a lack of clear actionable rules, and I’ve mapped a direct link between the six principles of drinking water security and corresponding principles for managing nutrient impacts in freshwater.

Six principles for freshwater

Of the six principles of drinking water safety, the first is perhaps the most obvious: drinking water safety deserves a “high standard of care”. Similarly, freshwater nutrient impact management should reflect a duty of care that mirrors the scale of impacts. Our most pristine freshwater, like Lake Taupo, and water on the verge of tipping into nearly irreversible degradation, deserve the greatest effort and care.

Second, drinking water safety follows a clear logic from the starting point: “protecting the integrity of source water is paramount”. For nutrient impact management in freshwater, we must reverse this and focus on a more forensic analysis along flowpaths to the source of excess nutrients entering water. Our current approach of using estimates of sources is not convincing when tracers could point to sources in the same way DNA can help identify who was at a crime scene. We must link impacts to sources.

Third, drinking water safety demands “multiple barriers to contamination”. For freshwater, we’re better off taking a similar but different approach – maximising sequential reductions of contamination. There are at least three main opportunities, including farm management, improving drains and riparian vegetation, and enhancing and restoring wetlands. If each is 50% effective at reducing contaminants reaching waterways, the three are as good as a single barrier that reduces contamination by 90%. The 50% reductions are likely to be much more achievable and cost effective.

Managing hot spots and hot moments

The fourth principle of drinking water safety was perhaps the most dramatic failure in the Havelock North drinking water crisis: “change precedes contamination”. Despite a storm and flood reaching areas of known risk for contaminating the water supply, there were no steps in place to detect changing conditions that breached the water supply’s classification as “secure” and therefore safe.

A similar, but inverted principle can keep nutrients on farm, where we want them, and keep them out of our water. Almost all processes that lead to nutrient excess and mobilisation, as well as its subsequent removal, occur in hot spots and hot moments.

This concept means that when we look, we find that roughly 90% of excess nutrients come from less than 10% of the land area, or events that represent less than 10% of time. We can identify these hot spots and hot moments, and classify them into a system of control points that are managed to limit nutrient contamination of freshwater.

Lake Taupo, New Zealand’s largest lake, has a nitrogen cap and trade programme in place, which allocates farmers individual nitrogen discharge allowances.
from Shutterstock, CC BY-SA

Establishing clear ownership

A fifth principle for drinking water seems obvious: “suppliers must own the safety of drinking water”. Clear ownership results in clear responsibility.

Two world-leading cap-and-trade schemes created clear ownership of nutrient contaminants reaching iconic water bodies. One is fully in place in the Lake Taupo catchment, and another is still under appeal in the Lake Rotorua catchment.

These schemes involved government investment of between NZ$70 million and NZ$80 million to “buy out” a proportion of nutrients reaching the lakes. This cost seems unworkable across the entire nation. Will farmers or taxpayers own this cost, or is there any way to pass it on to investors in new, higher-value land use that reduces nutrient loss to freshwater? A successful example of shifting to higher value has been conversions from sheep and beef farming to vineyards.

As yet, the ownership of water has made headlines, but remains largely unclear outside Taupo and Rotorua when it comes to nutrient contaminants. Consideration of taxing the use of our best water could be much more sensible with a clearer framework of ownership for both water and the impacts of contaminants.

The final principle of drinking water safety is to “apply preventative risk management”. This is a scaled approach that involves thinking ahead of problems to assess risks that can be mitigated at each barrier to contamination.

For nutrient management in water, a principled approach has to start with the basic fact that water flows and must be managed within catchments. From this standpoint, New Zealand has a good case for leading internationally, because regional councils govern the environment based on catchment boundaries.

Within catchments we still have a great deal of work to do. This involves understanding how lag effects can lead to a legacy of excess nutrients. We need to manage whole catchments by understanding, monitoring and managing current and future impacts in the entire interconnected system.

The ConversationIf we can focus on these principles, government, industry, researchers, NGOs and the concerned public can build understanding and consensus together, enabling progress towards halting and reversing the declining health and quality of our rivers and lakes.

Troy Baisden, Professor and Chair in Lake and Freshwater Sciences, University of Waikato

This article was originally published on The Conversation. Read the original article.