What spreads fires?
What are the risks and opportunities for fire control?

These are key questions that support fire mitigation and suppression work. Maps can help us answer them.

Although it will always be difficult to predict exactly how a fire will behave we do know what is likely to help fires spread and what might stop fires. These are also things we can map to help us decide where we should burn and to help us with suppression activities.

What helps fires spread is mainly dependent on how much fuel there is in the landscape, how dry it is and the weather conditions (wind, temperature and humidity). We can not use GIS to map fire weather but it can give us a good idea of current fuel conditions. Fuel loads are related to the type of grass vegetation and the time since it last burnt.

So what stops fires:

• Burnt areas. Obviously, country that has already burnt will have little fuel to carry a fire. Even some (e.g., spinifex) country that burnt the previous year may not have enough fuel the following year.
• Roads and fences. These are important lines in the landscape often with no or low fuel.
• Watercourses. Rivers most of the year and creeks, when they are wet, can be effective barriers to fire spread
• Wetlands/Mangroves and mudflats.

Making maps of the location of all of these features can help us think about how we manage the land to minimise fires escaping.

In this exercise, we will update our map bringing together these main features. Skip to video.

Creating a Burn Plan Map

To do this we need to utilise the high-resolution fire mapping for the year so far. These data are developed using satellites that provide a much better view of burnt areas than that shown with the standard NAFI burnt area mapping.

First, we’ll need to download the most up-to-date version of the data.  In the Data Links document in our data folder, we’ll find a link to where we can download the data from.  Click on the ‘High Resolution Burnt Area Mapping’ link.

This will open the storage location on your web browser where you can download the Burnt Area Mapping as several different file types.  For our use we will download the tif file.

Some web browsers will allow you to choose where to download the file to, in which case we want to choose our Data folder that we’ve been working from.  Other browsers will probably download it to the ‘Downloads’ folder automatically, so we need to navigate to that location and move the downloaded file to our Data folder.

Once that’s done, back in our QGIS project, we need to add the high-resolution fire mapping to our map.

The high-resolution mapping is symbolised with the same colours for each month as you see on NAFI, but the areas that haven’t been burnt are coloured white.  We want to make them no colour so we can still see the map. Double click on the new high-res burnt area mapping to open the symbology window:

In the symbology tab we see the colours for each month:

• Value 0 = no fire
• Value 1 = January
• Value 2 = February
• Value 2 = March
• etc….

We will change the colour for value 0 to be transparent.  Double clicking on a colour box enables you to change the colour and transparency.  Use the opacity slider to make the value 0 to be totally transparent:

Now we should have a map that shows us areas that have been mapped as already being burnt this year.  If you haven’t already, make sure to turn off the fire history layers so that the only fire data on the map is the high-resolution mapping.

**OPTIONAL**

Now is a good time to start adding other layers that you might have showing where fire will/won’t or should/should not burn. You will need use the browser panel to navigate to where your layers are stored to add them to your map.  Then, as we have done previously, open the properties for each layer to change the symbology to suit.