The interface between a developed area and a naturally-vegetated (e.g., forested) area is called the wildland-urban interface (WUI). Communities may be large and varied enough so that the hazard rating for fires varies within the WUI. High hazard areas are those that are highly susceptible to fire ignition or spread, which is a function of vegetation type & distribution, moisture, and other factors (e.g., topography).
A measure of people and houses living in or adjacent to wildland fuels. This is a measure of population potentially at risk, as well as exposure to wildfire from adjacent wildlands. Wildland includes all areas of hazardous fuels, which includes some areas within incorporated cities. Adjacency is defined by distance (using 30 meter cells) at risk of flying burning embers, by vegetation-based fuel type.
Not all fires will be suppressed equally. The degree of effort put into suppressing a fire may depend on its location relative to communities, the desire of agencies to promote natural fires in a particular area, and the difficulty of reaching and trying to manage the fire. The degree of effort is likely to determine the cost.
