‘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.

I made bushfire maps from satellite data, and found a glaring gap in Australia’s preparedness



Image courtesy of Greg Harvie, Author provided

Wallace Boone Law, University of Adelaide

On the night of January 9 2020, my wife and I secured our Kangaroo Island home and anxiously monitored the South Australian Country Fire Service (CFS) website for bushfire advice.

After many horrific weeks of bushfires, the winds had again shifted, and the fire front began a slow, nightmarish march eastward into the island’s central farmlands. Official warnings advised that the entire island was potentially under threat.

Landsat-8 false colour image of southwest Kangaroo Island, showing active bushfires on January 9, 2020.
Landsat-8, Author provided

As my good neighbours and volunteer firefighters headed off to battle the flames elsewhere on the island, I desperately wanted to find a way to help. With no firefighting training, I felt I physically had little to offer. But I reasoned that my skills and training in remote sensing and spatial science could potentially turn satellite information into useful maps to track the fires, in more detail than those provided by the Country Fire Service and Geoscience Australia.




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


While I was ultimately successful, it wasn’t quite as straightforward as I thought. And what I learned about access to good-quality and up-to-date satellite bushfire information surprised me.

Free satellite imagery is abundant; useful information is not

In principle, there are many good sources of free satellite imagery. But selecting, sourcing, understanding and processing a multilayered satellite image into an accurate burnt area map takes technical know-how that is beyond the reach of the people who need it the most.

We are fortunate to live in a time where satellite images are constantly uploaded to the web, often within hours of acquisition. There are many reputable sources for this information, including NASA Worldview, USGS Earth Explorer, USGS LandLook Viewer, and the Sentinel EO Browser.

These websites are gateways to the world of “big satellite data”, and I quickly found myself on a steep learning curve to efficiently navigate them and find recent imagery.

Once downloaded, the next hurdle I faced was how to process a data-rich satellite image into a meaningful and accurate map of the bushfire area. I scoured the internet for “how to” blogs, academic articles, spatial algorithms, and processing codes; these too are the products of much intellectual investment by global scientists, openly and freely available.

As a spatial scientist, I naturally found all this fascinating. But as a resident of an island under assault from bushfires, I also found it frustratingly time-consuming. I crashed my computer testing algorithms. I maxed out my hard drive. I spent hours on possibilities that turned out to be dead ends.

True colour satellite imagery is often the most accessible and easily understood, but it often lacks sufficient detail to clearly identify burnt areas. In this Sentinel-2 true colour image, approximately 210,000 hectares are burnt, but bushfire-impacted areas are barely visible without advanced image processing.
Sentinel-2, Author provided

Maps help to fight fires and recover from them

In the end, I produced burnt area maps from Sentinel and Landsat satellite images captured during the fires. I learned that this kind of information can indeed help firefighting and ecological recovery efforts, both during and after bushfires.

Initially I gave the maps to a group of farming friends who had been fighting fires around their properties for weeks. They told me the maps helped save time in assessing which areas had already burned, allowing them to focus on defending unburnt areas, and to make decisions on where to move livestock and install firebreaks.

The positive feedback inspired me to customise my processing techniques, so I could provide updates more quickly when new satellite images became available.

I embedded appropriate safety disclaimers into the maps and released them on Twitter and Spatial Points, a blog site managed by my research group at the University of Adelaide.

Within hours, I received messages that the maps were being used for ecological recovery efforts. The maps successfully highlighted remaining patches of habitat where endangered and vulnerable species had found refuge. Several government agencies even contacted me for burnt area information, which I’m told was used to assess infrastructure damage and habitat loss.

Processed Sentinel-2 satellite image. Red areas suggest burnt vegetation. Variation in red hues are caused by dominant vegetation type and soils.
Sentinel-2/W. Boone Law, Author provided

National knowledge gap

My experience shows there is a swag of free and regularly updated satellite imagery available, which when interpreted and presented appropriately can potentially be hugely helpful to firefighting and recovery efforts.

However, I am concerned that neither the general public nor decision-makers seem fully aware of the range of satellite information on offer. Nor is there a good understanding of the advanced technical skills needed to access and process imagery into useful map data.




Read more:
Yes, the Australian bush is recovering from bushfires – but it may never be the same


This leads me to wonder whether I have stumbled upon a glaring knowledge gap in Australia’s bushfire preparedness.

How can we overcome this technological and information bottleneck? I don’t propose to have all the answers, but I do believe it would be sensible for governments, industry and research agencies to invest in the kind of capabilities that I developed while trying to protect my own local community.

As Australia faces a future of more frequent and extreme bushfires, there will doubtless be many people who would be glad of this kind of information when they need it most.The Conversation

Wallace Boone Law, PhD Candidate, University of Adelaide

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

Satellite measurements of slow ground movements may provide a better tool for earthquake forecasting



File 20180819 165967 jkfubz.jpg?ixlib=rb 1.1
The 2016 Kaikoura earthquake shattered the surface and twisted railway lines.
Simon Lamb, CC BY-ND

Simon Lamb, Victoria University of Wellington

It was a few minutes past midnight on 14 November 2016, and I was drifting into sleep in Wellington, New Zealand, when a sudden jolt began rocking the bed violently back and forth. I knew immediately this was a big one. In fact, I had just experienced the magnitude 7.8 Kaikoura earthquake.

Our research, published today, shows how the slow build-up to this earthquake, recorded by satellite GPS measurements, predicted what it would be like. This could potentially provide a better tool for earthquake forecasting.




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Shattering the landscape

The day after the quake, I heard there had been huge surface breaks in a region extending for more than 170 km along the eastern part of the northern South Island. In some places, the ground had shifted by 10 metres, resulting in a complex pattern of fault ruptures.

In effect, the region had been shattered, much like a fractured sheet of glass. The last time anything like this had happened was more than 150 years ago, in 1855.

Quite independently, I had been analysing another extraordinary feature of New Zealand. Over the past century or so, land surveyors had revealed that the landscape is moving all the time, slowly changing shape.

These movements are no more than a few centimetres each year – but they build with time, relentlessly driven by the same forces that move the Earth’s tectonic plates. Like any stiff material subjected to excessive stress, the landscape will eventually break, triggering an earthquake.

I was studying measurements made with state-of-the-art global positioning system (GPS) techniques – and they recorded in great detail the build-up to the 2016 Kaikoura earthquake over the previous two decades.

A mobile crust

GPS measurements for regions at the edges of the tectonic plates, such as New Zealand, have become widely available in the last 15 years or so. Here, the outer part of the Earth (the crust) is broken up by faults into numerous small blocks that are moving over geological time. But it is widely thought that even over periods as short as a few decades, the GPS measurements still record the motion of these blocks.

New Zealand straddles the boundary between the Australian and Pacific tectonic plates, with numerous active faults. Note the locked portion of the underlying megathrust.
Simon Lamb, CC BY

The idea is that at the surface, where the rocks are cold and strong, a fault only moves in sudden shifts during earthquakes, with long intervening periods of inactivity when it is effectively “locked”. During the locked phase, the rocks behave like a piece of elastic, slowly changing shape over a wide region without breaking.

But deeper down, where the rocks are much hotter, there is the possibility that the fault is slowly slipping all the time, gradually adding to the forces in the overlying rocks until the elastic part suddenly breaks. In this case, the GPS measurements could tell us something about how deep one has to go to reach this slipping region, and how fast it is moving.

From this, one could potentially estimate how frequently each fault is likely to rupture during an earthquake, and how big that rupture will be – in other words, the “when and what” of an earthquake. But to achieve this understanding, we would need to consider every major fault when analysing the GPS data.

Invisible faults

Current earthquake forecasting “reverse engineers” past distortions of the Earth’s surface by finding all the faults that could trigger an earthquake, working out their earthquake histories and projecting this pattern into the future in a computer model. But there are some big challenges.

The most obvious is that it is probably impossible to characterise every fault. They are too numerous and many are not visible at the surface. In fact, most historical earthquakes have occurred on faults that were not known before they ruptured.

Our analysis of the GPS measurements has revealed a more fundamental problem that at the same time opens new avenues for earthquake forecasting. Working with statistician Richard Arnold and geophysicist and modeller James Moore, we found the GPS measurements could be better explained if the numerous faults that might rupture in earthquakes were simply ignored. In other words, surface faults seemed to be invisible when looking at the slow movements recorded by GPS.

There was only one fault that mattered – the megathrust that runs under much of New Zealand. It separates the Australian and Pacific tectonic plates and only reaches the surface underwater, about 50 to 100km offshore. Prior to the Kaikoura earthquake, the megathrust was locked at depths shallower than about 30km. Here, the overlying Australian plate had been slowly changing shape like a single piece of elastic.

Slip at depth on the megathrust drives earthquakes in New Zealand, including the M7.8 Kaikoura Earthquake.
Simon Lamb, CC BY

The pacemaker for future quakes

In the conventional view, every big fault has its own inbuilt earthquake driver or pacemaker – the continuously slipping part of the fault deep in the crust. But our analysis suggests that these faults play no role in the driving mechanism of an earthquake, and the pacemaker is the underlying megathrust.

We think the 2016 Kaikoura earthquake provides the vital clue that we are right. The key observation is that numerous ruptures were involved, busting up the boundary between the two plates in a zone that ran more-or-less parallel to the line of locking on the underlying megathrust. This is exactly what we would anticipate if the slow build-up in stress was only driven by slip on the megathrust and not the deeper parts of individual crustal faults.

I remember once watching a documentary about the making of the Boeing 777 aircraft. The engineers were very confident about its design limits under flying conditions, but the Civil Aviation Authority wanted it tested to destruction. In one test, the vast wings were twisted so that their tips arced up to the sky at a weird angle. Suddenly, there was a bang and the wings snapped, greeted by loud cheering because this had occurred almost exactly when predicted. But the details of how this happened, such as where the cracks of metal fatigue twisted the metal, were something that only the experiment could show.

I think this is a good analogy for realistic goals with earthquake prediction. The Herculean task of identifying every fault and its past earthquake history may be of only limited use. In fact, it is becoming clear that earthquake ruptures on individual faults are far from regular. Big faults may never rupture in one go, but bit by bit together with many other faults.

But it might well be possible to forecast when there will be severe shaking in a region near you – surely something that is equally as valuable.The Conversation

Simon Lamb, Associate Professor in Geophysics, Victoria University of Wellington

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

An artist’s surreal view of Australia – created from satellite data captured 700km above Earth



File 20180827 75981 h6vbep.jpg?ixlib=rb 1.1
Infrared and visible light satellite data is recoloured to produce striking images of Australia.
Grayson Cooke , Author provided

Grayson Cooke, Southern Cross University

There are more than 4,800 satellites orbiting Earth. They bristle with sensors – trained towards Earth and into space – recording and transmitting many different wavelengths of electromagnetic radiation.

Governments and media corporations rely on the data these satellites collect. But artists use it too, as a new way to image and view the Earth.

I work with Geoscience Australia and the “Digital Earth Australia” platform to produce time-lapse images and video of Australian landforms using satellite data.

My Open Air project, produced through a collaboration with Australian painter Emma Walker and the music of The Necks, features macro-photography of Emma Walker’s paintings set against time-lapse satellite imagery of Australia.

Open Air will be launched in Canberra on September 20, 2018.

Trailer: Open Air – showing Lake Gairdner in South Australia with turquoise desert, red salt lakes and pink clouds (Grayson Cooke 2017).



Read more:
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Open access to satellite data

We see satellites as moving pin-pricks in the night sky, or occasionally – as with the recent return to Earth of the Chinese Tiangong space station – as streaks of light. And most us would have heard about satellite data being used for surveillance, for GPS tracking and for media broadcasting.

But artists can divert satellite data away from a purely instrumental approach. They can apply it to produce new ways of seeing, understanding and feeling the Earth.

Of course satellites are expensive to launch and maintain. The main players are either powerful corporate providers like Intelsat, enormous public sector agencies like NASA and the European Space Agency (ESA), or private sector startups with links to these groups.

Luckily, many of these agencies make their data freely available to the public.

The NASA/US Geological Survey Landsat program makes 40 years of Earth imaging data available through Earth Explorer. The ESA provides data from their Sentinel satellites to users of the Copernicus Open Access Hub.

In Australia, Geoscience Australia‘s Digital Earth Australia platform provides researchers and the public with access to Australian satellite data from a range of agencies.

Landsat 8 image acquired in Australia in May 2013 over Cambridge Gulf and the Ord River estuary in Western Australia. Visible light bands highlight the different types of water within the estuary. Shortwave and near infrared bands highlight the mangroves and vegetation on the land.
Geoscience Australia, Author provided

Understanding and processing the data

Making satellite imaging data accessible, though, is not the same thing as making it usable. There is considerable technical know-how required to process satellite data.

The Landsat and Sentinel satellites are used by scientists and the private sector to monitor environmental change over time, using what is known as “remote sensing”. They travel in the low Earth orbit range, around 700km above the Earth and circle the Earth in around 90 minutes. After numerous orbits, they return to the exact same spot every 16 days.

Landsat and Sentinel satellites are equipped with sensors that record reflected electromagnetic radiation in a range of wavelengths. Some of these wavelengths fall within the visible light part of the spectrum (between 390-700 nanometers). In that sense, satellites image the Earth in a way comparable to a digital camera.

This image shows the percentage of time since 1987 that water was observed by the Landsat satellites on the floodplain around Burketown and Normanton in northern Queensland. The water frequency is shown in a colour scale from red to blue, with areas of persistent water observations shown in blue colouring, and areas of very infrequent water observation shown in red colouring.
Geoscience Australia, Author provided



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But the satellites also record other wavelengths, particularly in the near and shortwave infrared range. Vegetation, water and geological formations reflect and absorb infrared light differently to visible light. Recording these wavelengths allows scientists to track, for instance, changes in vegetation density or surface water location that indicate drought, flood or fire.

A single satellite image is made up of numerous bands recording data in very specific wavelengths. Getting a full-colour image requires processing in a GIS application to combine them, and assign the bands to either red, green or blue in an output image.

Images collected over 12 months at the Gulf of Carpentaria – 2016.
Grayson Cooke, Author provided

Bringing creativity to the data

This is where creativity can enter the picture. Being able to create false colour images that combine infrared and visible light in different ways allows me to produce beautifully surreal images of Australian landforms.

The image below shows the variance in environmental conditions over 12 months in 2016 at the Stirling Range National Park in WA.

A false colour image of Stirling Range National Park created by combining data relating to infrared and visible light.
Grayson Cooke, Author provided

Because geoscientists need clear images of the earth’s surface to analyse, they filter clouds from the data. I chose to take the opposite approach, highlighting the incredible array of meteorological conditions experienced by the country.

Clouds passing over the Eyre Peninsula in 2016.
Grayson Cooke, Author provided

There are many other artists working with satellite data. Clement Valla’s Postcards from Google Earth focuses on glitches in Google’s mapping algorithm, and bio-artist Suzanne Anker uses satellite imaging to produce extruded 3D environments in petri dishes.

Working with the Nevada Museum of Art, photographer Trevor Paglen will launch the Orbital Reflector satellite as an inflatable, visible sculpture, a prompt for wonder and reflection.

Artists place satellite data and usage in new contexts. They question surveillance practices and expose scientific tools and representations to new audiences outside science and the private sector.

The thousands of satellites winging their way around the Earth represent power and possibility, a chance to look again at the intersection between humankind and a changing planet.


“Open Air” will be officially launched at the National Film and Sound Archive in Canberra on September 20. It will also screen at the Spectra conference in Adelaide in October.The Conversation

Grayson Cooke, Associate Professor, Deputy Head of School (Research), Southern Cross University

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

Article: Papua New Guinea – Bagana Volcano Eruption


The following link is to an article reporting on the eruption of the Bagana Volcano in Papua New Guinea. The photo from a satellite in the article is brilliant.

For more visit:
http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=77975