Rocky Mountain Research Station

Fire Spread

• Fire Spread Probability (FSPro)

FSPro calculates the probability of fire spread from a current fire perimeter or ignition point for a specified time period. The model simulates the 2-D growth of the fire across the landscape (fuels & topography) using a computationally efficient form of the FARSITE calculations. FSPro differs from FARSITE in that it simulates fire growth for thousands of possible weather scenarios using the latest recorded perimeter (or point). Different weather possibilities are developed statistically using the data from the weather station (fuel moisture, wind speed and direction).

• Buffered fire perimeter or ignition point

In the absense of FSPro output, a buffered fire perimeter or ignition point may be used. Typical buffer zones are 1-mile, 5-miles and 7-miles. The resulting report and map are called a RIVaT (Rapid Inventory of Values Threatened) as opposed to a RAVAR.

Link to FSPro FAQ's

Private Structures

• County level geospatial cadastral data

Acquisition of the cadastral data has been coordinated by the National Cadastral Sub-Committee and resulted in the prestaging of structures layers for use in the RAVAR for approximately two thirds of all western US counties in 2007. The cadastral committee has reached out to local county offices including assessors, planners, natural resources, and GIS staffs, to acquire the county’s spatial (GIS) parcel records. From the cadastre record, a building clusters map is developed representing the general location of structures identified within the parcel records.

• Structure points derived from aerial photo interpretation

Where cadastral data is unavailable, structure points are derived from aerial photo interpretation. This product is produced by the USGS, Rocky Mountain Geographic Science Center.

Housing Values

Due to incomplete and varying cadastral spatial data records and privacy concerns, an alternative method for determining housing values was necessary. Additionally, for counties where no cadastral data has been identified the photo interpreted structure layer provided by the USGS will not include structure values.

US Census Bureau 2000 data for all owner-occupied housing units was used to calculate a county housing average. These values were updated to 2007 average values using the housing price index (HPI) from the Office of Housing Enterprise Oversight. The HPI provides a broad measure of the movement of single-family house prices (http://www.ofheo.gov/HPI.asp) and an accurate indicator of house price trends at various geographic levels. The median Census western tract average housing value of $147,500 is used as the minimum assigned value for counties where the average value is below this median.

Interpreting Total Structure Value in RAVAR

RAVAR is a strategic decision support tool, and, as such, the model’s goal is to simply quantify the values at risk to an ongoing fire event for strategic decision making. For tactical decision making such as which neighborhoods threatened by a fire should receive suppression resource priority the incident team should make that decision based on the best information available to them at the time. In terms of identifying the highest priority fires, when multiple fires threaten private residential values, the number of structures threatened by probability zone may be more informative than total value affected.

Infrastructure

Public infrastructure includes water supply systems and reservoirs, major power lines, pipelines, communication towers, recreation facilities, and other significant landmarks. Tier 1 also identifies designated wilderness and roadless areas, wild and scenic river corridors, and national recreation areas. Superfund sites and mines are mapped and reported along with other HAZMAT locations.

Regional Priority Assets

The RAVAR staff has coordinated the acquisition and staging of the appropriate layers for regional priority assets through direct interactions with regional Forest Service fire and natural resource staff members. The focus is on regionally identified natural resource and wildland management priorities. Examples include sensitive wildlife habitat, recreation zones, restoration priority areas, and Appropriate Management Response zones.

2007 List of Requested and Provided Tier II layers by region in WFDSS:
R1	Appropriate Management Response Areas (AMR), Integrated Restoration Strategy layers, Montana Private Property Stewardship Potential Priority Areas, Community Wildfire Protection Plans, Comprehensive Wildlife Conservation Plan Data, Research Natural Areas
R2	Unexploded Ordinance Areas- Military Training Areas, Nursing homes, Critical Soils
R3	Scenic Byways, Range Improvements, Class I airsheds and/or non-attainment areas, Invasive Species, Recreation values – trails, Special Use Permits, Recreation, Permits, Cabins
R4	Range Improvements, Active pasture, Suitable Timber – FSVEG
R5	Quincy Library Group deferred areas, Direct Protection Areas (DPA), developed recreation sites, Anadramous fish reaches, Giant Seqouia groves, Spotted Owl habitat, Late Successional Reserves
R6	State WUI layers, Spotted Owls habitat - NWFP Critical Habitats, Anadromous Fisheries Streams, State SHPOs cultural, NRIS Fauna sensitive and threatened species