2℃ of global warming would put pressure on Melbourne’s water supply



Sunburnt Victorian fields are set to become more common under climate change.
Fir0002/Flagstaffotos/Wikimedia Commons, CC BY-NC-SA

Ben Henley, University of Melbourne; Andrew King, University of Melbourne; Anna Ukkola, Australian National University; Murray Peel, University of Melbourne, and Rory Nathan, University of Melbourne

Melbourne’s existing water supplies may face pressure if global warming hits the 2℃ level, according to our new research published today in Environmental Research Letters.

The effects of drying and warming in southern Australia are expected to reduce natural water supplies. If we overshoot 2℃ of warming, even the desalination plant might not provide enough drinking water to a growing population.

However, keeping warming to 1.5℃ would help avoid many of these negative consequences. This brings home the local benefits of acting swiftly to limit global warming. Luckily, there are options available to secure our water supply.

Warming and drying effects

The Earth has warmed by about 1.1℃ since pre-industrial times, causing ongoing global changes to our atmospheric composition. The Paris Agreement commits the world to holding the increase to “well below” 2℃, and “pursuing efforts” to limit the increase to 1.5℃.

While we’re confident there will be more hot extremes and fewer cold extremes as global temperatures rise, the consequences of further global warming for other climate extremes – such as drought – in different parts of the world are harder to pinpoint.




Read more:
Is Australia’s current drought caused by climate change? It’s complicated


Our study uses climate models to identify the possible changes in average rainfall and temperature in four different worlds:

  • the “Natural” world, where humans have had no influence on the climate,

  • the “Current” world, which approximates the impacts humans have had to date, and

  • two future worlds, which are “1.5℃” and “2.0℃” warmer than pre-industrial times.

In line with previously published results, southern Australia is projected to undergo drying and warming. But we are not alone. The Mediterranean and Southwestern North America are also predicted to dry out.

Desalination is increasingly important

Most Australians recall the severity and length of the Millennium Drought. This event severely stressed agricultural and natural systems, and led to the commissioning of desalination plants in the five largest cities in Australia, at a cost of several billion dollars.

Desalination offers an important lifeline. Although it comes with high short-term costs, it supplies vital water security over the long term. Successful efforts to improve water-use efficiency have reduced per capita demand rates, but growing populations in major centres will lead to increasing water demand.

Rainfall deficiencies over Australia for the 18 months between 1 Feb 2018 and 31 July 2019.
Bureau of Meteorology

Right now, large parts of southeastern Australia are in the grips of another drought. Although drought is a common natural feature of Australia’s climate, in recent decades we have observed long-term drying trends over much of southern Australia.

Currently, all capital city urban reservoir systems in southern Australia are below 60%, and several are nearing or below 50%. The Victorian government recently ordered 125 gigalitres of water from the desalination plant.

Urban water storage levels for Australia’s capital cities.
Bureau of Meteorology

With these challenges in mind, our paper explores the effects of future climate change on the surface water supply infrastructure for Melbourne.

Climate models and hydrological models together indicate future declines in catchment inflows as global warming increases from 1.5℃ to 2℃. The good news is when desalination is added to the mix, which it is, pressure on our water storage is dramatically reduced. However, population growth and climate change remain key challenges into the future.

The buffer is shrinking

The take-home message is, if global warming approaches 2℃ and beyond, the combined impacts of climate change and population growth will ultimately begin to outstrip the buffer desalination provides for us without ongoing investment in water security. Fortunately, desalination plants, storm water, water recycling and continuing to improve efficiency are all viable options.

To ensure our water security, and with it, the safety and prosperity of the urban centres which are the engine houses of the Australian economy, we all need to be vigilant in managing water resources.

We also all need to play an active part in the global effort to reduce the impacts of climate change. The commitments by the world’s nations for the 2020-30 period remain insufficient to achieve the temperature goals. Global emission rates continue to rise, and atmospheric greenhouse gas concentrations are steadily accelerating.

The task of turning around our emissions in time to avert many of the serious impacts of climate change is becoming ever more implausible. In the coming 10–20 years, we expect to shoot past 1.5℃.




Read more:
Meet El Niño’s cranky uncle that could send global warming into hyperdrive


With so much momentum in both human and natural systems it is becoming increasingly unlikely that we will avoid warming beyond 1.5℃. However, if we can achieve it, the list of benefits includes greatly reduced stress on the water supplies we rely on for our very existence.The Conversation

Ben Henley, Research Fellow in Climate and Water Resources, University of Melbourne; Andrew King, ARC DECRA fellow, University of Melbourne; Anna Ukkola, Research Associate, Climate Change Research Centre, Australian National University; Murray Peel, Senior lecturer, University of Melbourne, and Rory Nathan, Associate Professor Hydrology and Water Resources, University of Melbourne

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

Budj Bim’s world heritage listing is an Australian first – what other Indigenous cultural sites could be next?



Ranger Trevor Bramwell on the walk up to the Split Rock art galleries in Cape York’s Quinkan Country in 2017.
Rebekah Ison/AAP

Claire Smith, Flinders University; Gary Jackson, Flinders University, and Jordan Ralph, Flinders University

The Budj Bim Cultural Landscape in south-west Victoria is the first Indigenous Australian landscape to be gazetted on the World Heritage List purely for its cultural values.

This listing breaks an invisible barrier: even the most iconic Indigenous Australian cultural sites, such as Uluru-Kata Tjuta and Kakadu National Parks, were listed for both natural and cultural values.




Read more:
The detective work behind the Budj Bim eel traps World Heritage bid


Could the Budj Bim listing open the door to other Australian Indigenous sites obtaining a World Heritage listing? Here are five that certainly deserve greater attention.

When considering them it’s important to understand how ancestral beings inhabit living Indigenous landscapes, which they created during the era known as the Dreaming.

Today, these beings continue to live in the land. They are seen by Indigenous people as powerful and intelligent, with the capacity to hurt those who don’t act in the right way. They can be in different places at the same time. And they see everything.




Read more:
Australia’s problem with Aboriginal World Heritage


The Dampier Archipelago (including the Burrup Peninsula)

The Dampier Archipelago, 1,550 kilometres north of Perth, has one of the most spectacular rock art landscapes in Australia. The richness and diversity of this art is extraordinary, ranging from small shelters to complexes with thousands of engravings. Some images are similar to those found hundreds of kilometres away in Depuch Island, the Calvert Ranges and Port Hedland, revealing ancient social connections spanning vast distances.

The Ngarda-Ngarlie people believe this area of land was created by the ancestral beings Ngkurr, Bardi and Gardi, who left their marks in its physical features. For instance, the blood of creative beings turned into stains that are now the Marntawarrura, or “black hills”.

Ancient Aboriginal rock art found amongst thousands of drawings and carvings near the Burrup Peninsula in Western Australia.
Robert G. Bednarik/AAP

Baiame’s Ngunnhu (Brewarrina Fishtraps)

The Brewarrina fishtraps, located in the Darling River near Brewarrina in New South Wales, are a clear example of Indigenous science. They offer material evidence of the Ngemba people’s advanced knowledge of dry-stone wall technology, river hydrology and fish ecology.

The Ngemba people believe the ancestral being Baiame revealed the innovative design of the traps by throwing his net over the river. With the help of his two sons, Baiame built the fishtraps in the shape of this net.

Nearly half a kilometre long, the fishtraps’ design and complexity is extraordinary. Dry-stone weirs and ponds were designed to take advantage of the specific configuration of the landscape and seasonal changes in river flows. The pond gates are strategically located to trap fish as they migrate both upstream and downstream. For thousands of years, these distinctive traps have been used to catch fresh water fish.

The fish traps at Brewarrina photographed in 2008.
Dean Lewins/AAP

Ngarrabullgan

Ngarrabullgan, a sacred and dangerous place in north Queensland, is an important example of congruence between Aboriginal traditions and archaeologically recorded changes in behaviours. Excavations show that Aboriginal people began living on Ngarrabullgan more than 37,000 years ago. They stopped camping there about 600 years ago.

There is no evidence of climate or environmental change at this time. Nor is there evidence of depopulation, which could have caused changes in site use. However, the Djungan people believe that a spiritual being called Eekoo lives on Ngarrabullgan (also known as Mt Mulligan). He can cause sickness by throwing stones, hooks or pieces of wood into a person’s body. This does not leave a mark.

Djungan people avoid going near the top of Ngarrabullgan where Eekoo lives to avoid disturbing him. They attribute any sickness when on the mountain to Eekoo.

Ngarrabullgan, also known as Mt Mulligan, in Queensland.
Wikimedia Commons

Quinkan country

The distinctive feature of Quinkan Country in the Cape York Peninsula in North Queensland is the richness, size and density of its Aboriginal paintings and engravings. This country is best known for its depictions of Quinkan spirit beings, tall, slender Timaras and fat-bodied Imjims (or Anurra).

The rock art of Quinkan Country provides insights into Aboriginal occupation of the north-east region of Australia. The cultural traditions, laws, and stories told there were developed over at least 37,000 years.

Ranger Trevor Bramwell points to rock paintings at Split Rock near the Cape York town of Laura in 2017, in the land known as Quinkan Country.
Rebekah Ison/AAP

Western Tasmania Aboriginal Cultural Landscape

The Western Tasmania Aboriginal Cultural Landscape provides evidence of a specialised and more sedentary way of life based on seals, shellfish and land mammals. This unusual Aboriginal way of life began around 2,000 years ago. It continued until the 1830s.

Shell middens in this landscape do not contain the remains of bony fish. However, they do contain “hut depressions”. Sometimes, these are formed into the shape of villages. Circular pits in cobble beaches are near some of these depressions. It is likely that they are hides that were used when hunting seals.

A shell midden in Tasmania.
Candice Marshall/AAP

Other candidates

These places already appear on our national heritage list. There is a plethora of other important ones, both on and off the list, including Mutawintji National Park, Gundabooka National Park and State Conservation area, and Koonalda Cave, on the Nullarbor Plain.

But Aboriginal owners and custodians must be the decision-makers when it comes to proposing a World Heritage listing. They have an inherited right to benefit from a listing – and they hold cultural responsibility for the consequences of it.
Protecting these living landscapes is their responsibility. Increased tourist activity could be a new source of income for them but it could also place cultural landscapes at risk.The Conversation

Claire Smith, Professor of Archaeology, College of Humanities, Arts and Social Sciences, Flinders University; Gary Jackson, Research Associate in Archaeology, Flinders University, and Jordan Ralph, PhD Candidate, Archaeology, Flinders University

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

This centuries-old river red gum is a local legend – here’s why it’s worth fighting for


Euan Ritchie, Deakin University

Sign up to the Beating Around the Bush newsletter here, and suggest a plant we should cover at batb@theconversation.edu.au.


In Dr Seuss’s The Lorax, his titular character famously said:

I am the Lorax. I speak for the trees. I speak for the trees, for the trees have no tongues.

In the midst of a global extinction crisis, the Lorax’s call to preserve what is precious couldn’t be more apt. The greatest threat to the survival of species globally continues to be habitat destruction and modification.




Read more:
The ring trees of Victoria’s Watti Watti people are an extraordinary part of our heritage


A potential and local victim of this ongoing environmental catastrophe is a single tree, and a tree I have a deep personal connection with. The tree I refer to is Bulleen’s iconic 300-year-old river red gum (Eucalyptus camaldulensis).

To me this tree has been a constant in my life. While everything else has changed around me, it has stood there, solid, just as solid as its red gum fibres are known to be.

As a child I fondly remember looking up at this tree in awe, as we’d often stop at the nearby service station on a hot summer’s day to buy a cold drink or ice-cream on the way to Saturday sport, the nearby Birrarung (Yarra River), or my grandmother’s house.



The Conversation

Bulleen’s majestic river red gum

It’s estimated to be approximately 20 metres in height with a canopy spread of 17 metres. And its trunk measures a whopping two metres across.

The tree is thought to be the oldest remnant of a once substantial red gum forest, and was saved by a local resident when the rest of the area was cleared for the construction of a service station.

It now faces destruction, as it is within the preferred path of construction for Victoria’s North East link.




Read more:
How I discovered the Dalveen Blue Box, a rare eucalypt species with a sweet, fruity smell


While the measurements of this tree are impressive, the splendour and value for me is that it has survived for so long and, in more recent times, against tremendous odds.

Surviving against all odds

The Bulleen red gum stands beside one of Melbourne’s busiest roads and the immediate area is covered with concrete and bitumen. The tree’s roots and health have therefore been challenged for a long time, and yet this massive red gum stands, as if in defiance of the modern world and the development that has encircled it.

Since this tree has survived for so long, it undoubtedly holds a special connection with so many: the Wurundjeri-willam people of the Kulin Nation, members of Australia’s famed Heidelberg school of artists who lived and worked in the near vicinty, everyday commuters that have driven or walked by or stopped to admire it, or the war verteran Nevin Phillips who once apparently defended it with his rifle against it being chainsawed.

Very old trees such as Bulleen’s river red gum deserve our respect and protection, for these trees have substantial environmental, economic and cultural value.
National Trust

Further proof of the value of this tree to so many is that it was awarded The National Trust of Australia’s (Victoria) 2019 Victorian Tree of the Year.

Why we must speak for and save old trees

I grew up near this tree and, like the Lorax, I would like to speak for it.
Trees as old as the Bulleen river red gum are now increasingly rare in our world, and beyond their strong personal and cultural values, including in some places as Aboriginal birthing sites, they are tremendously important for other reasons as well.




Read more:
Vic Stockwell’s Puzzle is an unlikely survivor from a different epoch


These trees provide shade and help keep our cities cooler, improve our mental health and wellbeing, and store considerable amounts of carbon aiding our fight against climate change.

Perhaps most importantly, under their bark and in their cracks and hollows, they provide homes for many of Australia’s precious but increasingly imperilled native wildlife, including bats, birds, possums and gliders, snakes and lizards, insects and spiders.

These homes are prime wildlife real estate, especially in our big cities, where such large old trees are vanishingly rare but where considerable wildlife, common and threatened, still persists. And yet more could survive with a helping hand from us.

A powerful owl chick in a tree hollow, in outer Melbourne.
John White (Deakin University)

As cities like Melbourne continue to grow around the world, there will be more and more cases where arguments of progress are used to justify the further destruction of what nature remains. But progress shouldn’t come at any cost, and in the case of preserving iconic and valuable trees such as Bulleen’s river red gum, it would seem there’s more than enough reasons to ensure this tree’s life and its many values continue.

Perhaps again the wise sage, the Lorax, says it best.

Unless someone like you cares a whole awful lot, Nothing is going to get better. It’s not.


Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.The Conversation

Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University

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

Australia: Victoria – Falls Creek Circuit


The link below is to an article that takes a look at a trek on Victoria’s ‘Fall Creek Circuit.’

For more visit:
https://weareexplorers.co/4-day-falls-creek-circuit/

What Australia can learn from Victoria’s shocking biodiversity record



File 20190320 93057 1dzh716.jpg?ixlib=rb 1.1
The endangered Brush-tailed Rock-wallaby is one of Victoria’s threatened species.
TARONGA ZOO/AAP

Geoffrey Wescott, Deakin University

Victoria is struggling with biodiversity conservation, according to a State of the Environment report tabled in parliament this week. While the scorecard is bleak – not one of the state’s key biodiversity indicators ranks as “good” – the report itself gives some hope.

For the first time the Commissioner for Environmental Sustainability, who prepared the report, offers proactive recommendations to the Victorian government for improving its performance, and has linked these goals to international sustainability targets. It’s an comprehensive and ambitious effort, and offers some good lessons to the rest of Australia.




Read more:
Australia among the world’s worst on biodiversity conservation


Alarming results

Victoria is the most densely populated state in Australia, the most cleared of native vegetation, and has the smallest percentage of public land.

The State of the Environment report uses a traffic light method to summarise the status, trend and data quality of 170 indicators spread over 12 scientific assessment areas (everything from general air and water quality to specific environments such as marine and coasts, plus issues such as waste and energy).

The indicators paint a picture that does not look good for biodiversity. None of these indicators are rated “good”; seven are “fair”, 21 “poor”, and seven “unknown”. In terms of trends, just one is improving, seven are stable, and 18 are deteriorating (nine are unclear).

National park declarations have slowed substantially on land in recent years – the first Andrews government (2014-18) was the first Victorian government in a quarter of a century not to increase national parks. Not a single additional marine area has been protected since 2002.

In contrast, conservation on private land is fair and trending upward according to the report card (probably largely due to the efforts of Trust for Nature). A substantial cash injection for the trust from Victoria’s rolling fund would likely see outsized results, although this is not a specific recommendation in the report.

The reports offers two critical recommendations for improving biodiversity:

  • increase private land conservation and invest in local government capability to enforce existing protective guidelines, and

  • appoint a Chief Biodiversity Scientist to counsel the Secretary and Environment Minister to improve the impact of biodiversity research.

Creating a Chief Biodiversity Scientist is a good starting point for an area that has received decreasing effort, over the past decade in particular. However, it must be only the first step in raising the lowly position of biodiversity conservation, not only in the environment department but across the entire government.

Beyond passive reporting

This years report moves beyond simply relaying data in two ways: first, with 20 specific recommendations to the government, and secondly by using the United Nation’s framework of environmental accounting to tie the report to the global Sustainable Development Goals.

The report claims this is the first attempt to apply the UN’s Sustainable Development Goals to a sub-national environmental report. Given the number of federated nations around the world (the United States, Brazil and Canada, for a start), putting the spotlight on state or provincial environmental responsibilities is a significant and laudable step.

In the more immediate future, the report gives the Victorian government 20 recommendations linked to the Sustainable Development Goals, across a range of categories: Traditional Owner leadership, climate change, air and water quality, land, forests, fire, marine and coastal environments, water resources, waste and resource recovery, energy, transport, and “megatrends”.

The 20 recommendations are solidly based on the findings across the 12 assessment areas. These show that only 11% of status indicators are “good”, whereas 32% are “poor”, with the trend demonstrating only 10% are improving, 30% stable and 30% deteriorating.




Read more:
Why biodiversity is key to our survival


While the State of the Environment report naturally focuses on Victoria, there are plenty of lessons and ideas here for the rest of the country.

Now the onus is firmly on the self-proclaimed “most progressive government in Australia” to act.The Conversation

Geoffrey Wescott, Honorary Research Fellow, School of Life and Environmental Sciences, Deakin University

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

It’s time to restore public trust in the governing of the Murray Darling Basin



File 20190114 43535 1d0sshz.jpg?ixlib=rb 1.1
Going all the way back: rules for the Murray Darling Basin are in Australia’s constitution.
KnitSpirit/Flickr, CC BY-NC-SA

Jason Alexandra, RMIT University

Fish deaths in the Darling River have once more raised the public profile of incessant political controversies about the Murray Darling Basin. These divisive debates reveal the deeply contested nature of reforms to water policy in the Basin.

It feels like Australia has been here before – algae blooms are not uncommon in these rivers. In 1992, the Darling suffered the world’s largest toxic algal bloom, over 1,000 kilometres long. This crisis became an iconic catalyst, and helped prompt the state and federal governments agreeing to water reforms in 1994.

Hopefully, our current crisis may be an opportunity to shine a strong light on the complexities of governing the Basin, and initiate the meaningful reforms needed to restore public trust.




Read more:
How is oxygen ‘sucked out’ of our waterways?


Forewarned is forearmed

The rivers of the basin are unique and precious. Australia needs high quality and independent science to understand them and guide their management. Unfortunately in 2012 state and federal governments cut three important programs that provided vital research on the Basin’s rivers:

So while yesterday’s announcement of A$5 million funding to a new native fish recovery program is welcome, good science alone is not enough. Good policy processes and robust institutions are needed to apply this information. We cannot continue to ignore expert warnings.

A crisis of trust

Since a 2017 Four Corners program exposed disturbing allegations of water theft and corruption, the media has revealed a host of further probity issues.

These and a plethora of formal inquiries into MDB governance indicates a crisis of trust, legitimacy and public confidence – in short, a loss of authority.

The 2018 federal Senate inquiry documents a litany of concerns, while disturbing evidence given at a South Australian Royal Commission raised substantive doubts about failures to heed the best scientific advice in the development of the Basin Plan.




Read more:
Explainer: what causes algal blooms, and how we can stop them


More Commonwealth oversight is not enough

Without doubt pressure is mounting for more reforms. The Senate’s Rural and Regional Affairs Committee and the Productivity Commission have recommended splitting the Murray Darling Basin Authority into two entities – the MDB Corporation and a MDB Regulator – in order to clearly separate the Commonwealth’s regulatory oversight from other roles.

These proposals deserve critical scrutiny. Structural reorganisation can provide an illusion of government action, but can have long-term effects on the efficacy and justice of water governance.

The Murray Darling has a unique place in Australia’s history, environment, economy and culture. Agreements about its governance have their origins in debates leading up to Federation in 1901. Any renegotiation needs to respect the Constitution and the different legal powers of the states and the Commonwealth.

So reform to institutional arrangements need bespoke design. These are the legitimate remit of our discursive democracy. Nonetheless, the OECD’s 12 water governance principles usefully provide guidance about the need for clarity of roles, transparency, effectiveness, efficiency and broad stakeholder engagement.

Current calls for reorganisation focus on clarifying the Commonwealth’s regulatory role, but this is fairly narrow. Reforms are needed at all scales.

The governance challenges in the MDB require modernisation and redesign of arrangements across regional, state and Commonwealth agencies. This includes structuring “constructive tensions” that ensure transparency and accountability. Just like the police don’t control the courts, we need to more clearly define and separate roles in the water sector.

Embracing radical transparency

We need all water agencies to adopt a formal charter of transparency and openness. All state and Commonwealth agencies should open their books to scrutiny, rather than hiding information behind claims of “commercial in confidence” or opaque “freedom of information” processes.

Greater transparency measures should also be a condition of all water licences. It’s entirely feasible to create modern monitoring regimes, using state-of-the art digital metering coupled with annual water-use declarations. These would be similar to tax returns enforced with random audits and satellite verification of areas irrigated. If made publicly available, all interested parties could audit water extractions.

But doubts don’t exclusively focus on irrigators’ compliance. We also need to address the states and their willingness and capability to enforce regulations. Policies of radical transparency could be supported with openly available water data. With digital meters and automated gauging of river flows, we could create a computer platform where anybody could develop river models using real data, in near real-time.

Harnessing the power of citizen involvement, trust and openly sharing information has been a hallmark of Australia’s landcare and natural resource management. This is where we should look for the next generation of governance in the Basin.

Open books means communities, industries, research and educational institutions can all help monitor our institutions and ensure rivers are managed in the public’s interest.




Read more:
Recent Australian droughts may be the worst in 800 years


Finally, droughts should not come as surprise. They are a recurrent feature of the Basin. With climate change, more frequent and intense droughts are predicted. As a nation we can do better than lurching from crisis to crisis each time drought returns.

We need careful deliberation about the institutions that will rebuild public confidence and restore trust in the governing of the Murray Darling. It’s time to develop a 21st century system that is cooperative, transparent and just.The Conversation

Jason Alexandra, PhD candidate, RMIT University

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

Logging must stop in Melbourne’s biggest water supply catchment


File 20181113 194488 ixuwud.png?ixlib=rb 1.1
Clearfell logging in the Thomson Catchment with the Thomson Reservoir in the background.
Chris Taylor

David Lindenmayer, Australian National University and Chris Taylor, Australian National University

Continued logging in Melbourne’s water catchments could reduce the city’s water supply by the equivalent of 600,000 people’s annual water use every year by 2050, according to our analysis.

We calculated water lost due to logging in the Thomson Catchment, which is the city’s largest and most important water supply catchment. Around 60% of Melbourne’s water is stored here.

Since the 1940s, 45% of the catchment’s ash forests (including mountain and alpine ash forest) have been logged. There are plans to log up to a further 17% of these forests under the VicForest’s existing logging plan.

Past logging in the ash forests has reduced the Thomson Catchment’s water yield, which is the amount of water that flows through the catchment, by 15,000 megalitres (a megalitre is a million litres) each year. This equates to around 9% of water yield from ash forests across the catchment.

By 2050, continued logging in these forests at the current rates could increase this loss to 35,000 megalitres each year, or 20% of water yield. This will be equal to the water use of around 600,000 people every year, based on estimated water use of 161 litres per person each day.

Thomson Catchment showing the extent of ash forest, with historic and planned logging (left) and annual rainfall distribution (right).
DELWP, 2018; Xu and Hutchinson 2018; DSE 2007.



Read more:
Ashes to ashes: logging and fires have left Victoria’s magnificent forests in tatters


Why forests are important for water supply

The city of Melbourne has some of the best quality water in the world. A key reason for this is that the city’s first water infrastructure planners closed many of the key water catchments to intensive human disturbance, such as logging.

But there also can be competition for water between different land uses in catchments that are not closed and open to logging. Indeed, it has long been known that logging can significantly reduce the amount of water produced from forests, especially those close to Melbourne.

Research on forest hydrology shows that the amount of water yielded from ash forests is related to forest age. Catchments covered with old-growth ash forests yield almost twice the amount of water each year as those covered with young forests aged 25 years. This is because evapotranspiration, the process by which trees transpire water into the atmosphere as well as evaporation from the surrounding land surface, is higher in young forests compared with older forests.

Up to 200,000 trees per hectare germinate following logging or an intense fire which burns the whole stand. Intense competition between young trees results in rapid growth rates along with increased evapotranspiration. As the forest matures, the trees thin out, and after 200 years, an ash forest can have less than 50 trees per hectare. These older ash forests release more water back into the catchment.




Read more:
Mountain ash has a regal presence: the tallest flowering plant in the world


With logging occurring every 60-120 years, large areas of ash forest are kept in a high evapotranspiration stage of growth, therefore releasing less water back into the catchment.

Perhaps the losses in water yield could be justified if the value of the timber and pulpwood produced from logging exceeded the value of water. However, previous research has shown that the water in these areas is 25.5 times more valuable than the timber and pulpwood from ash forests.

What can the Victorian government do?

The ash forests in the Thomson Catchment are logged primarily for paper manufacturing. Under the Forest (Wood Pulp Agreement) Act 1996, the Victorian government is bound to supply Australia’s largest pulp and paper mills at Maryvale, owned by the Nippon Paper Group, with at least 350,000 cubic metres of native forest logs each year. The Thomson Water Supply Catchment is allocated for logging under this Act.

If logging was stopped in the catchment, what is the alternative for these paper mills? The answer is to source wood from current plantations. In 2017, Victoria produced 3.9 million cubic metres of logs from plantations. This could supply the pulp and paper mills at Maryvale several times over.

A challenge facing Victoria’s forest industry is the loss of jobs. One major factor in this is out-of-state processing. Australia tends to import lower volumes
of more processed and higher value wood products, including printing and writing paper. By contrast, higher volumes of less processed and lower value wood products, such as woodchips and unprocessed logs – largely from plantations, are exported.

Redirecting plantation sourced logs and woodchips from export markets to domestic processing can address some of these problems. In fact, detailed analysis suggests doing this would have an overall positive economic impact for Victoria.

Stopping logging in the Thomson Catchment and sourcing instead from well managed plantations could both boost water supply and create more jobs. Of course, some jobs would be lost for people who log from the catchment, but this would be more than compensated for by employment in the plantation processing sector.

The first Wood Pulp Agreement Act of 1936, which legislated supply of pulplogs from Victorian state forest to earlier paper manufacturers in Maryvale, featured a clause stating logging was to cease following the designation of the Thomson Catchment in 1967. This has clearly not occurred. In fact 63% of logging in the ash forests across the catchment has occurred since 1967.

The Thomson Catchment is the only one of Melbourne’s large water supply catchments open to logging. Given the critical importance of the Thomson Catchment, our work clearly indicates the Victorian government needs to cease logging and prioritise the supply of water to the people of Melbourne.The Conversation

David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University and Chris Taylor, Research Fellow, Fenner School of Environment and Society, Australian National University

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