Spatially accurate representation of the nexus between development and wildfire is underpinned in this dataset by the use of Landscan 2012. Assessment dataset input_lsn_HousingDensity12_2 has four housing density classes: Specifically, remote sensed night time light emissions (Conus Night) data is converted to points, summarized into projected 90m grid cells using methods guided by the West Wide Wildfire Risk Assessment Final Report - Addendum I Detailed Technical Methods, March 31, 2013. The data is then resampled to 30m for consistency with other Assessment data products.

Housing Density Classes (DEN4) used in the WUI definitions:
Class Definition

1. Less than one house per 20 acres
2. One house per 20 acres to one house per 5 acres
3. More than one house per 5 acres to 1 house per acre
4. More than 1 house per acre

Interface:

DEN4 Class 2, 3 or 4

In Moderate, High, or Very High Fire Hazard Severity Zone

Not dominated by wildland vegetation (i.e., Lifeform not Herbaceous, Hardwood, Conifer or Shrub according to dataset input_FVEG15_2 )

Spatially contiguous groups of 30m cells that are 10 acres and larger

Intermix:

Not Interface

DEN4 Class 2

DEN4 Class 3, 4 dominated by wildland vegetation

In Moderate, High or Very High Fire Hazard Severity Zone

Improved Parcels only

Spatially contiguous groups of 30m cells 25 acres and larger
Wildfire Influence Zone

Wildland vegetation up to 1.5 miles from Interface or Intermix
Fire Hazard Severity Zones: