This page is actively in development
February 24, 2025
Dear fireexposuR users,
More details will be added to this page soon! For now, here are some considerations for choosing your raster data. You can find even more discussion about this topic in Forbes and Beverly (2024).
Best,
Air
Determine required input datasets
Consult the flowchart and table to determine the input data required
to reach a desired output. Note that using
fire_exp_validate() has more requirements, see the details
in the function documentation.
| Desired Output | Required Raster Data | Optional Raster Data | Required Vector Data | Optional Vector Data |
|---|---|---|---|---|
| Exposure | Hazardous Fuel | Non-Burnable | Area of Interest (Polygon) | |
| Directional Vulnerability Transects | Hazardous Fuel | Non-Burnable | Value (Point or Simple Polygon) | |
| Exposure to Values | Hazardous Fuel | Non-Burnable | Values (Multi-Point or Multi-Polygon) |
Raster Data
The hazardous fuel raster and optional non-burnable raster should be derived from the same land cover information product.
Determine minimum data requirements
The minimum spatial resolution and extent requirements will depend on a variable Transmission Distance and Area.
Minimum Spatial Resolution = Transmission Distance / 3
Minimum Spatial Extent = Area + Buffer of Transmission Distance
Transmission Distance
| Transmission Distance | |
|---|---|
| Long-range embers default | 500 m |
| Short-range embers default | 100 m |
| Radiant heat default | 30 m |
| Custom * | x m |
* the function fire_exp_adjust() can be used to set a
custom transmission distance. This is only recommended if the default
values do not represent fire behaviour in the area of interest.
Area
| Desired output | Area |
|---|---|
| Exposure | Optional provided polygon area OR input raster extent * |
| Transects | Value extent + Buffer of Total Transect Distance (default is 15000 m) |
| Values | Values extent + Buffer of Transmission Distance |
* Note that a negative transmission distance buffer will be lost due to edge effects
Additional considerations
Temporal resolution
When sourcing a ready-made land cover information product it may need to be updated to reflect the current land cover composition if it was produced in the past. Consider if there has been significant changes to land cover types between now and the data production date. For example, a dataset could be updated to reflect recent wildfire disturbances by overlaying fire perimeters.
land cover classifiers
When sourcing or creating a land cover information product it is also important to consider the classification scheme that is used. It needs to be possible to determine if a fuel will be hazardous at the chosen ‘Transmission Distance’ based on the classifier. For example, conifer fuels are considered hazardous to long-range ember transport in Alberta. If the land cover classifiers only specify if an area is “Forest” but does not differentiate between the tree species it would not be possible to determine which cells are hazardous for long-range embers.
References
Forbes AM, Beverly JL (2024) Influence of fuel data assumptions on wildfire exposure assessment of the built environment. International Journal of Wildland Fire 33, WF24025 DOI