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.

6 things to ask yourself before you share a bushfire map on social media



NASA’s Worldview software gives you a satellite view of Earth right now, and can help track the spread of fires.
Nasa Worldview

Juan Pablo Guerschman, CSIRO

In recent days, many worrying bushfire maps have been circulating online, some appearing to suggest all of Australia is burning.

You might have seen this example, decried by some as misleading, prompting this Instagram post by its creator:

As he explained, the image isn’t a NASA photo. What a satellite actually “sees” is quite different.

I’ll explain how we use data collected by satellites to estimate how much of an area is burning, or has already been burnt, and what this information should look like once it’s mapped.




Read more:
A crisis of underinsurance threatens to scar rural Australia permanently


Reflective images

When astronauts look out their window in space, this is what they see:

It’s similar to what you might see from an aeroplane window, but higher and covering a wider area.

As you read this, many unmanned satellites are orbiting and photographing Earth. These images are used to monitor fires in real-time. They fall into two categories: reflective and thermal.

Reflective images capture information in the visible range of the electromagnetic spectrum (in other words, what we can see). But they also capture information in wavelengths we can’t see, such as infrared wavelengths.

If we use only the visible wavelengths, we can render the image similar to what we might see with the naked eye from a satellite. We call these “true colour” images.

This is a true colour image of south-east Australia, taken on January 4th 2020 from the MODIS instrument on the Aqua satellite. Fire smoke is grey, clouds are white, forests are dark green, brown areas are dryland agricultural areas, and the ocean is blue.
NASA Worldview / https://go.nasa.gov/307pDDX

Note that the image doesn’t have political boundaries, as these aren’t physical features. To make satellite imagery useful for navigation, we overlay the map with location points.

The same image shown as true colour, with the relevant geographical features overlaid.
NASA Worldview / https://go.nasa.gov/2TafEMH

From this, we can predict where the fires are by looking at the smoke. However, the fires themselves are not directly visible.

‘False colour’ images

Shortwave infrared bands are less sensitive to smoke and more sensitive to fire, which means they can tell us where fire is present.

Converting these wavelengths into visible colours produces what we call “false colour” images. For instance:

The same image, this time shown as false colour. Now, the fire smoke is partially transparent grey while the clouds aren’t. Red shows the active fires and brown shows where bushfires have recently burnt.
NASA Worldview / https://go.nasa.gov/2NhzRfN

In this shortwave infrared image, we start to “see” under the smoke, and can identify active fires. We can also learn more about the areas that are already burnt.

Thermal and hotspots

As their name suggests, thermal images measure how hot or cold everything in the frame is. Active fires are detected as “hotspots” and mapped as points on the surface.

While reflective imagery is only useful when obtained by a satellite during daytime, thermal hotspots can be measured at night – doubling our capacity to observe active fires.

The same image shown as false color, with hotspots overlaid in red.
NASA Worldview / https://go.nasa.gov/2rZNIj9

This information can be used to create maps showing the aggregation of hotspots over several days, weeks or months.

Geoscience Australia’s Digital Earth hotspots service shows hotspots across the continent in the last 72 hours. It’s worth reading the “about” section to learn the limitations or potential for error in the map.




Read more:
Spread the word: the value of local information in disaster response


When hotspots, which show “hot” pixels, are shown as extremely big icons, or are collected over long periods, the results can be deceiving. They can indicate a much larger area to be under fire than what is really burning.

For example, it would be wrong to believe all the areas in red in the map below are burning or have already burnt. It’s also unclear over what period of time the hotspots were aggregated.

The ‘world map of fire hotspots’ from the Environmental Investigation Agency.
Environmental Investigation Agency / https://eia-international.org/news/watching-the-world-burn-fires-threaten-the-worlds-tropical-forests-and-millions-of-people/

Get smart

Considering all of the above, there are some key questions you can ask to gauge the authenticity of a bushfire map. These are:

  • Where does this map come from, and who produced it?

  • is this a single satellite image, or one using hotspots overlaid on a map?

  • what are the colours representing?

  • do I know when this was taken?

  • if this map depicts hotspots, over what period of time were they collected? A day, a whole year?

  • is the size of the hotspots representative of the area that is actually burning?

So, the next time you see a bushfire map, think twice before pressing the share button.The Conversation

Juan Pablo Guerschman, Senior Research Scientist, CSIRO

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