WILDLAND FIRE LEADERSHIP COUNCIL - WILDFIRE RISK AND HAZARD
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Fire risk assessment requires an understanding of the likelihood of wildfire by intensity level and the potential beneficial and negative effects to valued resources from fire at different intensity levels. This project was undertaken to achieve three broad goals:
1. To assess the trends and changes in fire hazard on federal lands in support of the Wildland Fire Leadership Council's (WFLC) monitoring strategy.
2. To develop information that can be used to evaluate the effectiveness of fuel treatments in reducing fire hazard and risk.
3. To Respond to queries by the Office of Management and Budget (OMB), General Accounting Office (GAO), and Congress into the effectiveness of fire management programs.
Burn probability raster data were generated using the large fire simulator - FSim - developed for use in the Fire Program Analysis (FPA). FSim uses historical weather data and current landcover data for discrete geographical areas (Fire Planning Units - FPUs) and simulates fires in these FPUs. Using these simulated fires, an overall burn probability and marginal burn probabilities at four fire intensities (flame lengths) are returned by FSim for each 270m pixel in the FPU.
FSim produces burn probabilities for six flame length classes. Summing the product of these burn probabilities and their respective flame length class midpoints equals the Conditional Flame Length (CFL) for the pixel. If the pixel burns, it most likely will burn at this intensity (flame length).
Selected Highly Valued Resources (HVR) were grouped into three initial value classes for the risk analysis:
Moderate HVR High HVR Very High HVR Campgrounds/Rec. Facilities Fire-susceptible USFWS listed Species Municipal Watersheds Historic/Scenic Trails Communication Towers Non-Attainment Areas (Air Quality) Class I Airsheds Elec. Transmission Lines Residential-Mod. and High Density Fire-Adapted Ecosystems Power Plants Oil and Gas Transmission Ski Areas Residential-Low Density Sage Grouse Habitat
HVRs were assigned to initial value classes based on their relative sociological and ecological value. The High HVR category risk was calculated both with and without sage-grouse habitat because the coarsely-mapped habitat concentrated in inland West overemphasized wildfire risk in these FPUs. Additionally, the listing status of the sage-grouse as a Threatened or Endangered Species is uncertain.
The response of these HVRs to fire can be expected to vary according to fire intensity. Some HVRs will benefit from low intensity fires while others will experience loss at any fire intensity. To account for this variation, response functions were assigned to each HVR/fire intensity combination. Response functions were determined by a panel of fire and fuels program management officials from federal wildland fire agencies. Risk was calculated for each individual HVR by summing the product of the burn probability at each fire intensity level and the resource response at that fire intensity and is presented as Total Change Equivalent (TCE) and Average Percent Change (APC). TCE is the equivalent area lost/gained, assuming 100 percent loss or gain, for a particular HVR as measured in acres. APC is TCE divided by the sum of burnable area of HVR in a given initial value category, which is an estimate of the average loss/gain for each pixel annually.
For details on data and methods see:Calkin, David E.; Ager, Alan A.; Gilbertson-Day, Julie, eds. 2010. Wildfire risk and hazard: Procedures for the first approximation. Gen Tech. Rep. RMRS-GTR-235. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 62p. To view/download this report click here .For a pdf file of the National (CONUS) Wildfire Risk and Hazard Report - click here .