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Mapping Canadian Wildland Fire Interface areas

Canadian Forest Service fire scientist Lynn Johnston completed this study under supervision by University of Alberta professor Mike Flannigan, as part of her MSc. degree completed in September 2016. Update: this work has been accepted for publication by the International Journal of Wildland Fire and is now available online. A copy of her thesis can be found here.


Although wildland fires are a beneficial ecosystem process, they can also cause destruction to human-built structures and infrastructure, as evidenced by disasters such as the BC wildfires in 2017, Fort McMurray fire in 2016 and the Slave Lake fires in 2011. This type of destruction occurs in the “wildland-urban interface” (WUI), which are areas where homes or other burnable community structures meet with or are interspersed within wildland fuels.

Photos showing typical wildland-urban interface areas, with a) showing a community bordering a forested area, and b) showing an isolated cabin amongst a forested area. Photo: a) Mike Flannigan / University of Alberta, b) Jeremy Johnston / Ontario Ministry of Natural Resources and Forestry.

The concept of the WUI can be expanded to industrial structures and infrastructure values. Here, the “wildland-industrial interface” refers to the interface of wildland fuels and industrial structures (e.g. oil and gas, or mining structures). The “infrastructure interface” is the interface of wildland fuels and infrastructure values (e.g. roads, powerlines, and railways). These industrial and infrastructure areas are not traditionally considered part of the WUI, but may require protection from fires and are important emerging issues.

In order to mitigate destructive interface fires, basic information such as the location of these areas is required. Unfortunately, Canada does not have national scale, high-resolution interface maps for use in research or fire management, hindering our ability to study and manage/mitigate fires in interface areas. Therefore, this study focused on defining and mapping the three interface types (i.e. WUI, wildland-industrial interface, and infrastructure interface) for the national area of Canada. All three interface types were defined as areas of wildland fuels which are within a variable-width buffer (maximum distance: 2400 m) from potentially vulnerable structures or infrastructure.

Nationally, it was found that Canada has 32.3 million ha of WUI (3.8% of total national land area), 10.5 million ha of wildland-industrial interface (1.2%), and 109.8 million ha of infrastructure interface (13.0%). The images below show the national maps.

Total number of homes or the total number of residents living in the interface could not be directly estimated in this study due to limits of the input data. However, 60% of all cities, towns, settlements, and reservations across Canada were found to have a significant amount of WUI (defined as those with more than 500 ha of WUI within a 5 km radius; shown in purple in the image below) and therefore may have the potential for interface fire issues.

The results of this study provide a baseline for future research, including fire risk mapping, change detection, and future predictions of interface areas. There are also a wide variety of practical applications, including various topics in wildfire mitigation (e.g. FireSmart and industrial fire regulations), long-term planning (e.g. city planning and insurance), and wildfire decision support (e.g. fire prioritization and risk modelling).

Map of “Populated Places” by relative population size (“Population Class” 4 = population of over 1 000 000, 3 = 100 000 – 999 999, 2 = 10 000 – 99 999, 1 = 1– 9 999) in Canada; points shown in purple indicate a substantial amount of wildland-urban interface (WUI; > 500 hectares) and points in grey indicate very little (possibly zero) WUI (0 – 500 hectares).

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