‘It is quite startling’: 4 photos from space that show Australia before and after the recent rain



National Map

Sunanda Creagh, The Conversation

Editor’s note: These before-and-after-images from several sources –NASA’s Worldview application, National Map by Geoscience Australia and Digital Earth Australia – show how the Australian landscape has responded to huge rainfall on the east coast over the last month. We asked academic experts to reflect on the story they tell:


Warragamba Dam, Sydney

Stuart Khan, water systems researcher and professor of civil and environmental engineering.

This map from Digital Earth Australia shows a significant increase in water stored in Lake Burragorang. Lake Burragorang is the name of water body maintained behind the Warragamba Dam wall and the images show mainly the southern source to the lake, which is the Wollondilly River. A short section of the Coxs River source is also visible at the top of the images.

The Warragamba catchment received around 240mm of rain during the second week of February, which produced around 1,000 gigalitres (GL) of runoff to the lake. This took the water storage in the lake from 42% of capacity to more than 80%.

Unlike a typical swimming pool, the lake does not generally have vertical walls. Instead, the river valley runs deeper in the centre and more shallow around the edges. As water storage volumes increase, so does the surface area of water, which is the key feature visible in the images.

Leading up to this intense rainfall event, many smaller events occurred, but failed to produce any significant runoff. The catchment was just too dry. Dry soils act like a sponge and soak up rainfall, rather than allowing it to run off to produce flows in waterways.

The catchment is now in a much wetter state and we can expect to see smaller rainfall events effectively produce further runoff. So water storage levels should be maintained, at least in the short term.

However in the longer term, extended periods of low rainfall and warm temperatures will make this catchment drier.

In the absence of further very intense rainfall events, Sydney will lapse back into drought and diminishing water storages.

This pattern of decreasing storage, broken only by very intense rainfall, can be observed in Sydney’s water storage history.

It is a pattern likely to be exacerbated further in future.


Wivenhoe Dam, Brisbane

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Stuart Khan, water systems researcher and professor of civil and environmental engineering.

Lake Wivenhoe is the body of water maintained behind Wivenhoe Dam wall in southeast Queensland. It is the main water storage for Brisbane as well as much of surrounding southeast Queensland.

This image from National Map shows a visible change in colour from brown to green in the region around the lake. It is quite startling.

This is especially the case to the west of the lake, in mountain range areas such as Toowoomba, Warwick and Stanthorpe. Many of these areas were in very severe drought in January. Stanthorpe officially ran out of water. The February rain has begun to fill many important water storage areas and completely transformed the landscape.

Unfortunately, this part of Australia is highly prone to drought and we can expect to see this pattern recur over coming decades.

Much climate science research indicates more extreme weather events in future. That means more extreme high temperatures, more intense droughts and more severe wet weather.

There are many challenges ahead for Australian water managers as they seek to overcome the inevitable booms and busts of future water availability.




Read more:
Bushfires threaten drinking water safety. The consequences could last for decades


Australia-wide

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Grant Williamson, Research Fellow in Environmental Science, University of Tasmania

It’s clear from this map above, from NASA Worldview, the monsoon has finally arrived in northern Australia and there’s been quite a lot of rain.

On the whole, you can see how rapidly the Australian environment can respond to significant rainfall events.

It’s important to remember that most of that greening up will be the growth of grasses, which respond more rapidly after rain.

The forests that burned will not be responding that quickly. The recovery process will be ongoing and within six months to a year you’d expect to see significant regrowth in the eucalyptus forests.

Other more fire-sensitive vegetation, like rainforests, may not exhibit the same sort of recovery.




Read more:
‘This crisis has been unfolding for years’: 4 photos of Australia from space, before and after the bushfires


Grant Williamson, Research Fellow in Environmental Science, University of Tasmania

This slider from National Map shows both fire impact, and greening up after rain.

On the left – an area west of Cooma on December 24 – you can see the yellow treeless areas, indicating the extent of the drought, and the dark green forest vegetation. This image also shows quite a lot of smoke, as you’d expect.

On the right – the area on February 22 – a lot of those yellow areas are now significantly greener after the rain. However, some of those dark green forest areas are now brown or red, where they have been burnt.

It’s clear there is a long road ahead for recovery of these forests that were so badly burned in the recent fires but they will start resprouting in the coming months.

Grant Williamson is a Tasmania-based researcher with the NSW Bushfire Risk Management Research Hub.The Conversation


Sunanda Creagh, Head of Digital Storytelling, The Conversation

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

Heavy rains are great news for Sydney’s dams, but they come with a big caveat


Ian Wright, Western Sydney University and Jason Reynolds, Western Sydney University

Throughout summer, Sydney’s water storage level fell alarmingly. Level 2 water restrictions were imposed and the New South Wales government prepared to double the capacity of its desalination plant.

But then it began to rain, and rain. Sydney water storages jumped from 41% in early February to 75% now – the highest of any capital city in Australia.

This is great news for the city, but it comes with a big caveat. Floodwaters will undoubtedly wash bushfire debris into reservoirs – possibly overwhelming water treatment systems. We must prepare now for that worst-case pollution scenario.

Reservoirs filled with rain

The water level of Sydney’s massive Lake Burragorang – the reservoir behind Warragamba Dam – rose by more than 11 meters this week. Warragamba supplies more than 80% of Sydney’s water.

Other Sydney water storages, including Nepean and Tallowa dams, are now at 100%.
WaterNSW report that 865,078 megalitres of extra water has been captured this week across all Greater Sydney’s dams.

This dwarfs the volume of water produced by Sydney’s desalination plant, which produces 250 megalitres a day when operating at full capacity. Even at this rate, it would take more than 3,400 days (or nine years) to match the volume of water to added to Sydney’s supply this week.

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The Warragamba Dam before the drought and after the recent heavy rains.

But then comes the pollution

Thankfully, the rain appears to have extinguished bushfires burning in the Warragamba catchment for months.

But the water will also pick up bushfire debris and wash it into dams.

Over the summer, bushfires burnt about 30% of Warragamba Dam’s massive 905,000 hectare water catchment, reducing protective ground cover vegetation. This increases the risk of soil erosion. Rain will wash ash and sediment loads into waterways – adding more nitrogen, phosphorous and organic carbon into water storages.




Read more:
Bushfires threaten drinking water safety. The consequences could last for decades


Waterways and ecosystems require nutrients like phosphorous and nitrogen, but excess nutrients aren’t a good thing. They bring contamination risks, such as the rapid growth of toxic blue-green algae.

Drinking water catchments will always have some degree of contamination and water treatment consistently provides high quality drinking water. But poor water quality after catchment floods is not without precedent.

We’ve seen this before

In August 1998, extreme wet weather and flooding rivers filled the drought-affected Warragamba Dam in just a few days.

This triggered the Cryptosporidium crisis, when the protozoan parasite and the pathogen Giardia were detected in Sydney’s water supplies. It triggered health warnings, and Sydneysiders were instructed to boil water before drinking it. This event did not involve a bushfire.




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Better boil ya billy: when Australian water goes bad


The Canberra bushfires in January 2003 triggered multiple water quality problems. Most of the region’s Cotter River catchments, which hold three dams, were burned. Intense thunderstorms in the months after the bushfire washed enormous loads of ash, soil and debris into catchment rivers and water reservoirs.

This led to turbidity (murkiness), as well as iron, manganese, nitrogen, phosphorus and carbon in reservoir waters. The inflow of organic material also depleted dissolved oxygen which triggered the release of metals from reservoir sediment. At times, water quality was so poor it couldn’t be treated and supplied to consumers.

The ACT Government was forced to impose water restrictions, and built a A$38 million water treatment plant.

Have we come far enough?

Technology in water treatment plants has developed over the past 20 years, and water supply systems operates according to Australian drinking water guidelines.

Unlike the 1998 Sydney water crisis, WaterNSW, Sydney Water and NSW Health now have advanced tests and procedures to detect and manage water quality problems.

In December last year, WaterNSW said it was aware of the risk bushfires posed to water supplies, and it had a number of measures at its disposal, including using booms and curtains to isolate affected flows.

However at the time, bushfire ash had already reportedly entered the Warragamba system.

The authors crossing the Coxs River during very low flow last September.
Author provided

Look to recycled water

Sydney’s water storages may have filled, but residents should not stop saving water. We recommend Level 2 water restrictions, which ban the use of garden hoses, be relaxed to Level 1 restrictions which ban most sprinklers and watering systems, and the hosing of hard surfaces.

While this measure is in place, longer term solutions can be explored. Expanding desalination is a popular but expensive option, however greater use of recycled wastewater is also needed.




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Highly treated recycled water including urban stormwater and even treated sewage should be purified and incorporated into the water supply. Singapore is a world leader and has proven the measure can gain community acceptance.

It’s too early to tell what impact the combination of bushfires and floods will have on water storages. But as extreme weather events increase in frequency and severity, all options should be on the table to shore up drinking water supplies.The Conversation

Ian Wright, Senior Lecturer in Environmental Science, Western Sydney University and Jason Reynolds, Senior Lecturer in Geochemistry, Western Sydney University

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

You can leave water out for wildlife without attracting mosquitoes, if you take a few precautions



Leaving water out for wildlife is important during droughts and bushfires but if it’s not changed regularly it can be a breeding ground for mosquitoes.
Roger Smith/Flickr, CC BY-NC

Cameron Webb, University of Sydney

Australia is in for a long, hot summer. The recent bushfires have been devastating for communities and wildlife. Drought is also impacting many regions.

Understandably, people want to leave water out for thirsty birds and animals.

Health authorities generally warn against collecting and storing water in backyards as one measure to protect against mosquito bites and mosquito-borne diseases caused by, for example, dengue and Ross River viruses.




Read more:
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But it’s possible to leave water out for wildlife – and save water for your garden – without supplying a breeding ground for mosquitoes, if you take a few precautions.

For some mozzies, any water will do

Mosquitoes often look for wetlands and ponds to lay their eggs. But sometimes, anything that holds water – a bucket, bird bath, drain or rainwater tank – will do.

When the immature stages of mosquitoes hatch out of those eggs, they wriggle about in the water for a week or so before emerging to fly off in search of blood.

While there are many mosquitoes found in wetlands and bushland areas, Aedes notoscriptus and Culex quinquefasciatus are the mosquitoes most commonly found in our backyards and have been shown to transmit pathogens that cause mosquito-borne disease.

The Australian backyard mosquito (Aedes notoscriptus) is quick to take advantage of water-filled containers around the home.
Cameron Webb (NSW Health Pathology)

In central and north Queensland, mosquitoes such as Aedes aegypti can bring more serious health threats, such as dengue, to some towns.




Read more:
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Mosquitoes can also impact our quality of life through bites as well as the nuisance of simply buzzing about our bedrooms and backyards.

So how can you stop mozzies making a home in your backyard?

Empty water containers once a week

Mosquitoes need access to standing water for about a week or so. Reduce the number of water-filled containers available or how long that water is available to mosquitoes.

Emptying a water-filled container once a week will stop the immature mosquitoes from completing their development and emerging as adults.

If you’re leaving water out for pets or wildlife, use smaller volume containers that will allow for easy emptying once a week. You can tip any remaining water into the garden, as mosquito larvae won’t survive if they’re “stranded” on soil.

For larger or heavier items, such as bird baths, flushing them out once a week with the hose will knock out most of the wrigglers and stop the mosquitoes completing their life cycle.

Make sure garden water doesn’t slosh about

Be careful with self-watering planter boxes. These often have a reservoir of water in their base and, while it may seem like a water-wise idea, these can turn into tiny mozzie hotels!

A simple trick to keep water available to plants, but not mosquitoes, is to fill your potted plant saucers with sand. The sand traps and stores some moisture but there is no water sloshing about for mosquitoes.

If you’re collecting water from showers, baths, or washing machines (commonly known as grey water), use it immediately on the garden, don’t store it outside in buckets or other containers.




Read more:
How drought is affecting water supply in Australia’s capital cities


Gutters, ponds, tanks and pools

Make sure your roof gutters and drains are free of leaves and other debris that will trap water and provide opportunities for mosquitoes.

Ensure rainwater tanks (and other large water-storage containers) are appropriately screened to prevent access by mosquitoes.

Rainwater tanks can be a useful way to conserve water in our cities but they can also be a source of mosquitoes.
Cameron Webb (NSW Health Pathology)

A well maintained swimming pool won’t be a source of mosquitoes. But if it’s turning “green”, through neglect and not intent, it may become a problem. Mosquitoes don’t like the chlorine or salt treatments typically used for swimming pools but when there is a build up of leaves and other detritus, as well as algae, the mosquitoes will move in.




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For backyard ponds, introducing native fish can help keep mosquito numbers down.

But if you want your pond to be a home for frogs, avoid fish as they may eat the tadpoles. Instead, try to encourage other wildlife that may help keep mosquito numbers down by creating habitats for spiders and other predatory insects, reptiles, frogs, birds, and bats.

Avoiding excessive use of insecticides around the backyard will help encourage and protect that wildlife too.

Mozzies can still come

There isn’t much that can be done about those mosquitoes flying in from over the back fences from local bushland or wetland areas.

Mosquitoes are generally most active at dusk and dawn so keep that in mind when planning time outdoors. But when mosquito populations are peaking, they’ll be active almost all day long.

Applying an insect repellent can be a safe and effective way to stop those bites.




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Covering up with long pants, long-sleeved shirt and shoes will provide a physical barrier to mosquitoes. If you’re spending a lot of time outdoors, perhaps even consider treating your clothing with insecticide to add that extra little bit of protection.

Make sure insect screens are installed, and in good condition, on windows and doors. Mosquitoes outdoors can be bad; you don’t want them inside as well.The Conversation

Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney

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

Weather bureau says hottest, driest year on record led to extreme bushfire season



It’s the first time since overlapping records began that Australia experienced both its lowest rainfall and highest temperatures in the same year.
dan HIMBRECHTS/AAP

David Jones, Australian Bureau of Meteorology; Karl Braganza, Australian Bureau of Meteorology, and Skie Tobin, Australian Bureau of Meteorology

The Bureau of Meteorology’s annual climate statement released today confirms 2019 was the nation’s warmest and driest year on record. It’s the first time since overlapping records began that Australia experienced both its lowest rainfall and highest temperatures in the same year.

The national rainfall total was 37mm, or 11.7%, below the 314.5 mm recorded in the previous driest year in 1902. The national average temperature was nearly 0.2°C above the previous warmest year in 2013.

Globally, 2019 is likely to be the second-warmest year, with global temperatures about 0.8 °C above the 1961–1990 average. It has been the warmest year without the influence of El Niño.

Across the year, Australia experienced many extreme events including flooding in Queensland and large hail in New South Wales. However, due to prolonged heat and drought, the year began and ended with fires burning across the Australian landscape.




Read more:
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Part of Menindee Lakes on the Darling River, which is under pressure from low water flow as a result of the prolonged drought.
Dean Lewins/AAP

The effect of the long dry

Bushfire activity for the 2018–19 season began in late November 2018, when fires burned along a 600km stretch of the central Queensland coast. Widespread fires later followed across Victoria and Tasmania throughout the summer.

Persistent drought and record temperatures were a major driver of the fire activity, and the context for 2019 lies in the past three years of drought.

The dry conditions steadily worsened over 2019, resulting in Australia’s driest year on record, with area-average rainfall of just 277.6mm (the 1961–1990 average is 465.2 mm).



Almost the entire continent experienced rainfall in the lowest 10th percentile over the year.

Record low rainfall affected the central and southern inland regions of the continent and the north-eastern Murray–Darling Basin straddling the NSW and Queensland border. Many weather stations over central parts of Australia received less than 30mm of rainfall for the year.

Every capital city recorded below average annual rainfall. For the first time, national rainfall was below average in every month.



Record heat dominates the nation

2019 was Australia’s warmest year on record, with the annual mean temperature 1.52°C above the 1961–1990 average, surpassing the previous record of 1.33°C above average in 2013.

January, February, March, April, July, October, November, and December were all amongst the ten warmest on record for Australian mean temperature for their respective months, with January and December exceeding their previous records by 0.98°C and 1.08°C respectively.

Maximum temperatures recorded an even larger departure from average of +2.09°C for the year. This is the first time the nation has seen an anomaly of more than 2 °C, and about half a degree warmer than the previous record in 2013.



The year brought the nation’s six hottest days on record peaking at 41.9°C
(December 18), the hottest week 40.5 °C (week ending December 24), hottest month 38.6 °C (December 2019), and hottest season 36.9 °C (summer 2018–19).

The highest temperature for the year was 49.9 °C at Nullarbor (a new national December record) on December 19 and the coldest temperature was –12.0°C at Perisher Valley on June 20.

Keith West in southeast South Australia recorded a maximum 49.2°C on December 20, while Dover in far southern Tasmania saw 40.1°C on March 2, the furthest south such high temperatures have been observed in Australia.

Accumulating fire danger over 2019

The combination of prolonged record heat and drought led to record fire weather over large areas throughout the year, with destructive bushfires affecting all states, and multiple states at once in the final week of the year.

Many fires were difficult to contain in regions where drought has been severe, such as northern NSW and southeast Queensland, or where below average rainfall has been persistent, such as southeast Australia.

The Forest Fire Danger Index, a measure of fire weather severity, accumulated over the month of December was the highest on record for that month, and the highest for any month when averaged over the whole of Australia.



Record-high daily index values for December were recorded at the very end of December around Adelaide and the Yorke Peninsula in South Australia, East Gippsland in Victoria and the Monaro in NSW. These regions which experienced significant fire activity.

Don’t forget the floods

Amidst the dry, 2019 also included significant flooding across Queensland and the eastern Top End.

Heavy rain fell from January into early February, with damaging floods around Townsville and parts of the western Peninsula and Gulf Country.

Tropical cyclone Trevor brought further heavy rainfall in April in the eastern Northern Territory and Queensland. Floodwaters eventually reached Lake Eyre/Kati Thanda which, amidst severe local rainfall deficiencies in South Australia, experienced its most significant filling since 2010–11.

There was a notable absence of rainfall on Australia’s snow fields during winter and spring which meant less snow melt. Snow cover was generous, particularly at higher elevations.

A Townsville resident removes damaged items from a house after the Townsville floods in early 2019.
Dan Peled/AAP

What role did climate change play in 2019?

The climate each year reflects random variations in weather, slowly evolving natural climate drivers such as El Niño, and long-term trends through the influence of climate change.

A strong and long-lived positive Indian Ocean Dipole – another natural climate driver – affected Australia from May until the end of the year, and played a major role in suppressing rainfall and raising temperatures for much of the year.

Spring brought an unusual breakdown of the southern polar vortex which allowed westerly winds to affect mainland Australia. This reduced rainfall, raising temperature and contributing to the increased fire risk.

Climate change continues to cause long-term changes to Australia’s climate. Conditions in 2019 were consistent with trends of declining rainfall in parts of the south, worsening fire seasons and rising temperatures.




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The Conversation


David Jones, Climate Scientist, Australian Bureau of Meteorology; Karl Braganza, Climate Scientist, Australian Bureau of Meteorology, and Skie Tobin, Climatologist, Australian Bureau of Meteorology

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

The science of drought is complex but the message on climate change is clear



Detecting human fingerprints on complex events like droughts is not straightforward.
AAP Image/Dan Peled

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

The issue of whether Australia’s current drought is caused by climate change has been seized on by some media commentators, with debate raging over a remark from eminent scientist Andy Pitman that “there is no link between climate change and drought”. Professor Pitman has since qualified, he meant to say “there is no direct link between climate change and drought”.

A highly politicised debate that tries to corner scientists will not do much to help rural communities struggling with the ongoing dry. But it is still worthwhile understanding the complexity of how climate change relates to drought.




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


So, why the contention?

It may seem like splitting hairs to focus on single words, but the reality is drought is complex, and broad definitive statements are difficult to make. Nevertheless, aspects of drought are linked with climate change. Let us try to give you a taste of the complexity.

First, it’s important to understand that drought is a manifestation of interactions between the atmosphere, ocean, and land. In Australia, the Bureau of Meteorology uses rainfall deficiencies to identify regions that are under drought conditions. Anyone on the land doesn’t need to be reminded, but the current drought is seriously bad. These maps show the patterns of rainfall deficiency over the past 36 and 18 months, highlighting the severity and extent of what we call meteorological drought.

Widespread rainfall deficiencies over the last 36 months (left) and 18 months (right)
Australian Bureau of Meteorology

But along with the main driver – low rainfall – droughts can also be exacerbated by water loss through evaporation. This depends not only on temperature but also humidity, wind speeds, and sunshine. Temperature will clearly continue to rise steadily almost everywhere. For the other factors, the future is not quite as clear.

Water loss also varies according to vegetation cover. Plants respond to higher carbon dioxide levels and drought by closing the tiny holes in their leaves (the stomata) and this can actually reduce water loss in wet environments. However, in water-stressed environments, projected long-term declines in rain may be compounded by plants using more water, further reducing streamflow. Actually, we can glean a lot from studying hydrological drought, which is measured by a period of low flow in rivers.

The point here is droughts are multidimensional, and can affect water supply on a wide range of spatial and temporal scales. A seasonal-scale drought that reduces soil moisture on a farm, and a decade-long drought that depletes reservoirs and groundwater supplies, can each be devastating, but in different ways.

Is climate change affecting Australian droughts?

Climate change may affect drought metrics and types of drought differently, so it can be hard to make general statements about the links between human-induced climate change and all types of drought, in all locations, on all timescales.

Southern Australia, and in particular the southwest, has seen a rapid decline in winter rainfall and runoff that has been linked to climate change. In the southeast there has also been a substantial decline in winter rainfall and total runoff in recent decades. Although the reductions are consistent with climate change projections, the trend so far is harder to distinguish from the year-to-year variability.

There is some evidence to suggest that widespread and prolonged droughts, like the Millennium Drought, are worse than other droughts in past centuries, and may have been exacerbated by climate change.




Read more:
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But the role of climate change in extended drought periods is difficult to discern from normal variations in weather and climate. This is particularly true in Australia, which has a much more variable climate than many other parts of the world.

What does the future hold?

Climate models project increasing temperature across Australia and a continuing decline in cool-season rainfall over southern Australia over the next century. This will lead to more pressure on water supplies for agriculture, the environment, and cities such as Melbourne at the Paris Agreement’s target of 2℃, relative to the more ambitious target of 1.5℃ of global warming.




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Rainfall is projected to become more extreme, with more intense rain events and fewer light rain days. Declining overall rainfall is predicted to reduce river flows in southeastern Australia. While we can expect the largest floods to increase with climate change, smaller floods are decreasing due to drier soils, and it is these smaller floods that top up our water supply systems.

Action needed

We might not know enough about droughts to be certain about exactly how they will behave in the future, but this does not affect the message from the science community on climate change, which remains crystal clear.

Rainfall intensification, sea level rise, ocean acidification, hotter days, and longer and more intense heatwaves all point to the fact that climate change presents a major threat to Australia and the world.

In response to these threats, we need deep and sustained greenhouse gas emissions cuts and proactive adaptation to the inevitable effects of climate change. This includes a focus right now on the practical measures to help our rural communities who continue to feel the pinch of a dry landscape.




Read more:
Why 2℃ of global warming is much worse for Australia than 1.5℃


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 Fellow, Australian National University; Murray Peel, Senior lecturer, University of Melbourne; Q J Wang, Professor, 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.

We can’t drought-proof Australia, and trying is a fool’s errand



The push to ‘drought-proof’ Australia is dangerous nonsense.
AAP Image/Mick Tsikas

Emma Kathryn White, University of Melbourne

There is a phrase in the novel East of Eden that springs to mind every time politicians speak of “drought-proofing” Australia:

And it never failed that during the dry years the people forgot about the rich years, and during the wet years they lost all memory of the dry years. It was always that way.

While author John Steinbeck was referring to California’s Salinas Valley, the phrase is particularly pertinent to Australia where the El Niño-Southern Oscillation exerts a profound influence. Water availability varies greatly across the country, both in space and time. El Niño conditions bring droughts and devastating bushfires, while La Niña is accompanied by violent rainfall, floods and cyclones.




Read more:
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This variability is innate to the Australian environment. And now, climate change means that in some regions, the dry years are becoming drier and the wet years are becoming less frequent. Managing water resources under a changing climate and burgeoning population requires innovative and realistic solutions that are different to those that have worked in the past.

Drought-proofing is impossible

Planning for the dry years involves setting sustainable usage limits, using more than one source of water, efficiency improvements, managed aquifer recharge, water recycling and evaluation of the best usage of water resources. It does not involve misleading claims of drought-proofing that infer we can somehow tame the unruly nature of our arid environment instead of planning and preparing for reality.

Unlike managing for the wet and dry periods, drought-proofing seeks to negate dry periods through infrastructure schemes such as large dams (subject to huge evaporative losses) and dubious river diversions. It fails to acknowledge the intrinsic variability of water availability in Australia, and modify our behaviour accordingly.

The reality is that in many parts of the country, groundwater is the sole source of water and the climate is very dry. A cornerstone of the recently launched $100 million National Water Grid Authority is the construction of more dams. But dams need rain to fill them, because without rain, all we have is empty dams. And we have enough of those already.

A history of denial

Just because Dorothea Mackellar wrote of “droughts and flooding rains” over 100 years ago, it doesn’t mean water management should proceed in the same vein it always has.

Australia has always had a variable climate, which changes significantly from year to year and also decade to decade. This not the same as a long-term climatic trend, better known as climate change.




Read more:
“Weather” and “climate” are used interchangeably. They shouldn’t be


Climate change is making parts of Australia even drier. Rainfall in the south-eastern part of Australia is projected to keep declining. We cannot rely on blind faith that rains will fill dams once more because they have in the past.

Yet inevitably, during the dry years, claims that Australia can be “drought-proofed” are renewed. Deputy Prime Minister Michael McCormack recently praised the Bradfield scheme, an 80 year old infrastructure project intending to divert northern river flows inland. It has been so thoroughly debunked on all scales, it is better described as a pipe-dream than piping scheme. It has no place in reasonable water management discourse.

The concept of drought-proofing harks back to the days of European settlement. Early water management techniques were more appropriate for verdant English fields than the arid plains of Australia.

In the early twentieth century, water resources were vigorously developed, with government-sponsored irrigation schemes and large dams constructed. During this time, little thought was given to sustainability. Instead, the goal was to stimulate inland settlement, agriculture and industry. Development was pursued despite the cost and ill-advised nature of irrigation in particular areas.

Shifting long entrenched perceptions of water management

All this said, irrigation certainly has its place: it supports a quarter of Australia’s agricultural output. And there are substantial efforts underway to rebalance water usage between irrigation and the environment.

However, acknowledgement of the relative scarcity of water in certain parts of Australia has only really occurred in the last 30 years or so.

Widespread droughts in the late 1970s and early 1980s highlighted the importance of effective water management and shifted long-entrenched perceptions of irrigation and development. Water reforms were passed, mandating future water development be environmentally sustainable development, which meant, for the first time, water resource management sought a balance between economic, social and environmental needs.

Antiquated ideas about drought-proofing, pushed by politicians, promise much yet deliver little. They distract attention and siphon funds from realistic solutions, or actually re-evaluating where and how we use our limited water resources.




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We need practical, effective and well-considered management such as water recycling, efficiency measures and source-divestment that accounts for both shorter term climatic variability and long term changes in temperature and rainfall due to climate change. A big part of this is managing expectations through education.

Attempting to drought-proof Australia is not “managing for the dry periods”, as advocates claim. It is sticking our heads in the dry, salty sand and pretending the land is cool and green and wet.The Conversation

Emma Kathryn White, PhD Candidate, Infrastructure Engineering, University of Melbourne

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

The winter was dry, the spring will likely be dry – here’s why


Jonathan Pollock, Australian Bureau of Meteorology and Andrew B. Watkins, Australian Bureau of Meteorology

Winter still has a few days to run, but it’s highly likely to be one of Australia’s warmest and driest on record. While final numbers will be crunched once August ends, this winter will probably rank among the top ten warmest for daytime temperatures and the top ten driest for rainfall.

While it was drier than average across most of the country, it was especially dry across South Australia, New South Wales and southern Queensland. Small areas of South Australia and New South Wales are on track for their driest winter on record.




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In contrast, parts of southern Victoria, western Tasmania and central Queensland were wetter than usual.

Preliminary winter 2019 rainfall deciles.
Bureau of Meteorology

Thirsty ground

Soil moisture normally increases during winter (except in the tropics, where it’s the dry season), and while we saw that in parts of Victoria, for most of Queensland and New South Wales the soil moisture actually decreased.

Dry soils leading into winter have soaked up the rain that has fallen, resulting in limited runoff and inflows into the major water storages across the country.

A glass half empty

Sydney’s water storages dropping below 50% received considerable public attention, and unfortunately a number of other regional storages in New South Wales and the Murray Darling Basin are much lower than that.

The winter ‘filling’ season in the southern Murray Darling Basin has been drier than usual for the third year in a row, and storages in the northern Murray Darling basin are extremely low or empty with no meaningful inflows.

Some rain in the west

Some regions did receive enough rainfall to grow crops this cool season. However, northern New South Wales and southern Queensland didn’t see an improvement in their severe year-to-date rainfall deficiencies over winter.

In fact, the area of the country that is experiencing year-to-date rainfall in the lowest 5% of historical records expanded.

In better news, the severe year-to-date deficiencies across southwest Western Australia shrank during winter.

Indian Ocean Dipole the culprit

Sustained differences between sea surface temperatures in the tropical western and eastern Indian Ocean are known as the Indian Ocean Dipole (IOD). The IOD impacts Australian seasonal rainfall and temperature patterns, much like the more well known El Niño–Southern Oscillation.

Warm sea surface temperatures in the tropical western Indian Ocean and cool sea surface temperatures in the eastern Indian Ocean, along with changes in both cloud and wind patterns, have been consistent with a positive Indian Ocean Dipole since late May.

International climate models, some of which forecast the positive IOD as early as February, agree that it is likely to continue through spring.

Typically, this means below average rainfall and above average temperatures for much of central and southern Australia, which is consistent with the current rainfall and temperature outlook from the Bureau’s dynamical computer model. The positive IOD is likely to be the dominant climate driver for Australia during the next three months.

Comparison of international climate model forecasts of the IOD index for November 2019.
Models from the Australian Bureau of Meteorology, Canadian Meteorological Centre, European Centre for Medium-Range Weather Forecasts, Meteo France, National Aeronautics and Space Administration (USA) and the Met Office (UK)

A dry end to 2019 likely

Chances are the remainder of 2019 will be drier than normal for most of Australia. The exceptions are western Tasmania, southern Victoria and western WA, where chances of a wetter or drier than average end to the year are roughly equal.

The spring 2019 outlook showing low chances of above average rainfall for most of the country.
Bureau of Meteorology

Warmer than average days are very likely (chances above 80%) for most of the country except the far south of the mainland, and Tasmania.

Nights too are likely to be warmer than average for most of the country. However, much of Victoria and Tasmania, and southern parts of South Australia and New South Wales have close to an even chance for warmer than average minimum temperatures.

Due to the warm and dry start to the year, the east coast of Queensland, New South Wales, Victoria and Tasmania, as well as parts of southern Western Australia, face above normal fire potential this coming bushfire season.

More outlooks more often

The term weather describes conditions over shorter periods, such as from minutes to days, while the term climate describes the more slowly varying aspects of the atmosphere.

From today, the Bureau of Meteorology is closing the forecast gap between weather and climate information with the release of weekly and fortnightly climate outlooks.

For the first time, rainfall and temperature outlooks for the weeks directly after the 7-day forecast are available. One- and two-week outlooks have been added to complement the existing 1-month and 3-month outlooks.




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The new outlook information for the weeks ahead also features how much above or below average temperatures are likely to be, and the likelihood of different rainfall totals.

The Bureau’s outlook videos explain the long-range forecast for the coming months.
Bureau of Meteorology


You can find climate outlooks and summaries on the Bureau of Meteorology website here.The Conversation

Jonathan Pollock, Climatologist, Australian Bureau of Meteorology and Andrew B. Watkins, Manager of Long-range Forecast Services, Australian Bureau of Meteorology

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

There’s a simple way to drought-proof a town – build more water storage



Inland towns need far more water storage.
Flickr/Mertie, CC BY-SA

Michael Roderick, Australian National University

The federal parliament has voted to funnel A$200 million to drought-stricken areas. What exactly this money will be spent on is still under consideration, but the majority will go to rural, inland communities.

But once there, what can the money usefully be spent on? Especially if there’s been a permanent decline in rainfall, as seen in Perth. How can we help inland communities?




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Let’s look at the small inland town of Guyra, NSW, which is close to running dry. Unlike our coastal cities, Guyra cannot simply build a billion-dollar desalination plant to supply its water. Towns like Guyra must look elsewhere for its solutions.

Running dry isn’t just about rainfall

“Running dry” means there is no water when the tap is turned on. It seems to make sense to blame the drought for Guyra’s lack of water. But the available water supply is not only determined by rainfall. It also depends on amount of water flowing into water storage (called streamflow), and the capacity and security of that storage.

While Perth has had a distinct downturn in its rainfall since the 1970s and has built desalination plants to respond to this challenge, no such downturn is evident at Guyra. Indeed, to date, the driest consecutive two years on record for Guyra were 100 years ago (1918 and 1919).

Long-term rainfall records for Perth (left) and Guyra (right). Dashed red line shows the trend and the full yellow line shows 600 mm annual rainfall.
Bureau of Meteorology

Despite the differences, there are some similarities between Perth and Guyra. As a rule of thumb, in Australia, significant streamflow into water storages does not occur until annual rainfall reaches around 600mm. This occurs as streamflow is generally supplied from “wet patches” when water can no longer soak into the soil. Thus, if annual rainfall is around 600mm or below, we generally anticipate very little streamflow.

While Guyra has seen some rain in 2019, it is not enough to prompt this crucial flow of water into the local water storage. The same is true for Perth, with annual rainfall in the past few decades now hovering close to the 600mm threshold.

Importantly, rainfall and streamflow do not have a linear relationship. Annual rainfall in Perth has declined by around 20%, but Perth’s streamflow has fallen by more than 90%.

With little streamflow filling its dams, Perth had little choice but to find other ways of increasing its water supply. They built desalination plants to make up the difference.

Let’s return to Guyra in NSW and the current drought. The rainfall records do not indicate there is a long-term downward trend in rainfall. But even without a rainfall trend, there are still dry years when there is little streamflow. Indeed, in Guyra, the rainfall record shows that, on average, the rainfall will be 600mm or less roughly one year out of every ten years.

Build more storage

So how do the residents of Guyra ensure a reliable water supply, given that they cannot build themselves a desalination plant?

Well, in this case, you can simply get water from somewhere else if it is available. A pipeline is currently under construction to supply Guyra from the nearby Malpas Dam, and is expected to be in operation very soon.

But that’s not always an option. A made-in-Guyra water solution means one thing: expanding storage capacity.

Guyra can generally store around 8 months of their normal water demand (although of course demand varies with the seasons, droughts, water restrictions and price per litre).

To give a point of comparison, Sydney can store up to five years of its normal water demand, and has a desalination plant besides. Despite these advantages, Sydney residents are now under stage one water restrictions which happens when its storages are only 50% full. Yet, even when Sydney’s glass is only half-full, that city still has at least another two years of water left to meet the expected water demand even without using desalination.

By comparison, when water storages in Guyra are 50% full, they have less than six months normal water supply.

It is astonishingly difficult to find accurate data on small-town water supplies but in my experience Guyra is not unique among rural towns. There is a big divide between the water security of those living in Australia’s big cities compared to smaller inland towns. Many rural communities simply do not have sufficient water storage to withstand multi-year droughts, and in some cases, cannot even withstand one year of drought.




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Nature, drought and climate change cannot be blamed for all of our water problems. In rural inland towns, inadequate planning and funding for household water can sometimes be the real culprit. Whether Australians live in rural communities or big cities, they should be treated fairly in terms of both the availability and the quality of the water they use.The Conversation

Michael Roderick, Professor, Research School of Earth Sciences and Chief Investigator in the ARC Centre of Excellence for Climate Extremes, Australian National University

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

Drought and climate change are driving high water prices in the Murray-Darling Basin


Neal Hughes, Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES)

Water prices in the southern Murray-Darling Basin have reached their highest levels since the worst of the Millennium drought more than a decade ago. These high water prices are causing much anxiety in the region, and have led the federal government to call on the Australian Competition and Consumer Commission to hold an inquiry into the water market.

Inevitably, whenever an important good becomes more expensive – be it housing, electricity or water – there is a rush to identify potential causes and culprits. In the past few years high water prices have been blamed on foreign investors, corporate speculators, state government water-sharing rules, new almond plantings and the Murray-Darling Basin Plan.




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While some of these factors have had an effect on the market, they are in many ways a distraction from the simpler truth: that high water prices have mostly been caused by a lack of rain.

Supply drives the market

The waters of the northern basin run to the Darling River and the waters of the southern basin run to the Murray River.
MDBA

Market reforms in the 1980s and 1990s enabled water trading in many parts of Australia. By far the most active market exists in the southern Murray-Darling basin, which covers the Murray River and its tributaries in northern Victoria, southern New South Wales and eastern South Australia.

The market allows users – mostly irrigation farmers – to trade their water allocations (effectively shares of water in the rivers’ major dams). This trading helps ensure limited water supplies go to the farmers who value them the most, which can be crucial in times of drought.

Historical data shows the main driver of water market prices in the southern basin is change in water supply.

The following chart shows storage volumes (in orange) and water prices (in red) in the southern basin since 2006. Prices peaked at the height of the Millennium drought in 2007. During the floods of 2011, they fell near zero. Prices have increased again during the latest drought, and are now at their highest levels in a decade.


Water allocation prices and storage volumes in the southern Murray-Darling Basin.
State government trade registers, BOM, Ruralco Water, ABARES estimates.

Lower rainfall, higher temperatures

While water prices have always been higher in dry years and lower in wet, we’ve been getting a lot more dry years in recent decades.

Over the past 20 years, rainfall, run-off and stream flow in the southern basin has been far less than historical conditions.

The below chart shows modelled flow data for the Murray River, assuming historical weather conditions and no water extraction, over the past century. It shows that average water flows this century are about 40% below the average of the 20th century.


Modelled ‘without-development’ annual Murray River flow, 1900 to 2018.
Murray-Darling Basin Authority.

We know these reductions are at least partly related to climate change, driven by both reduced winter rainfall and higher temperatures.

Lower rainfall and higher temperatures also make crops thirstier, increasing demand for irrigation water. This was evident in January, when temperatures exceeded 35℃ for 14 days and irrigators’ demand for water spiked from about 4.5 gigalitres to 7 gigalitres a day.




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The basin plan in perspective

The Murray-Darling Basin Plan seeks to improve the environmental health of the river system by recovering water rights from irrigation farmers. To date, more than 1,700 gigalitres of water rights – about 20% of annual water supply – have been recovered in the southern basin.

By reducing supply, water recovery was always expected to increase water prices. However, the effects of water recovery on supply – while significant – are still small relative to the effects of climate over the same period, as shown in the below chart.


Water allocation use in the southern basin with and without water recovery.
State government agencies, Department of Agriculture, ABARES estimates.

Measuring the precise effect of water recovery on prices is difficult. Water buybacks are straightforward and have been modelled by ABARES and others. But the effects of infrastructure programs – where farmers return a portion of their water rights in exchange for funding to upgrade infrastructure – are harder to estimate.




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‘Carryover’ rule changes

Historically farmers had to use water allocations within a 12-month window. The introduction of “carryover” – most recently in Victoria in 2008 – means users can now hold their unused water in dams. This rule change was a good thing, as it encourages farmers to conserve water and build up a buffer against drought.

But it might also have contributed to anxiety about the water market’s operations.

Since water allocations can be bought and held for multiple years, information about future conditions can have a big effect on prices now. For example, we see large jumps in price following news of worse-than-expected supply forecasts. This may have helped fuel concern about “speculators”.

Over the longer-term, the ability to store water helps to “smooth” water prices, with slightly higher prices in most years offset by much lower prices in drought years. Again this is a good thing, but it may have added to the perception of higher prices in the market.

Water demand is rising

When a profitable new irrigation activity is willing to pay more for water – as is the case with almond farms in the southern basin – competition for limited supplies can potentially drive up prices.

ABARES’ research shows that between 2003 and 2016 there was little change in irrigation demand (aside from that linked to rainfall). Growth in demand from expanding activities such as almonds and cotton was offset by reductions in others including dairy, rice and wine grapes. However, there is evidence since 2016 that demand for water has started to increase, contributing to higher water prices. Longer-term projections suggest this trend may continue.

With drought and climate change reducing water supply, and demand for both environmental and irrigation water increasing, high water prices are only likely to become more common in the basin in future.The Conversation

Neal Hughes, Senior Economist, Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES)

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