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The RCI Project Team was composed of experts in the fields of fire behavior and suppression, geographic information systems (GIS), and natural resource ecology who collaborated to complete a Community Risk/Hazard Assessment for each community. The RCI Project Team included Fire Specialists with extensive wildland fire prevention and suppression experience in Nevada and Natural Resources Specialists experienced in the Great Basin environment.
The RCI Project Team used standardized procedures developed from the Draft Community Wildland Fire Assessment For Existing and Planned Wildland Residential Interface Developments in Nevada during the assessment process (Nevada’s Wildland Fire Agencies, Board of Fire Directors, April 2001; revised 2002). This approach incorporates values for fuel hazards, structural hazards, community preparedness, and fire protection capabilities into an overall community rating.
The RCI Project Team Geographic Information Specialists compiled and reviewed existing statewide geospatial data to create field maps for recording baseline data and data verification. Data sources for the maps were the Nevada Fire Safe Council, the Nevada Department of Transportation, the Natural Resource Conservation Service, the US Forest Service, and the Bureau of Land Management. Datasets and sources utilized are summarized in Table 2-1.
|Spatial Dataset||Data Source|
|Land ownership||BLM Nevada State Office Mapping Services|
|Vegetation communities||Nevada Gap Analysis Program Data, Utah Cooperative Fish and Wildlife Research Unit, Utah State University|
|Topography||US Geological Survey Digital Elevation Models and Topographic Maps|
|Fire suppression resources||Field Interviews|
|Roads||“TIGER” Census data 2000|
|Current aerial photographs||US Geological Survey Digital Orthophoto Quadrangles (1994, 1996, or 1998)|
|Soil surveys||BLM Nevada State Office Mapping Services
Natural Resources Conservation Service “SSURGO” Website
|Fuel types||BLM Nevada State Office Fire Hazard Potential Data|
|Fire History||BLM Nevada State Office Mapping Services
USFS Humboldt-Toiyabe Supervisor’s Office
National Interagency Fire Center
Existing data were reviewed and pertinent information compiled on maps in geographic information system (GIS) format. The RCI Project Team verified the GIS data during field assessments. The GIS Specialist provided the data management for quality assurance and accuracy of the statewide geospatial data and map production.
Wildfire history was mapped using Bureau of Land Management and US Forest Service datasets and GIS databases that identify wildfire perimeters on federally managed lands covering the past 21 years. This database was compiled by agency personnel using GPS and screen digitizing on source maps with a minimum detail of 1:250,000. This dataset was updated at the BLM Nevada State Office at the end of each fire season from information provided by each Nevada BLM Field Office. The dataset is the central source of historical GIS fire data used for fire management and land use planning on federal lands.
The Fire Specialists on the RCI Project Team identified additional fire perimeters as a result of interviews with local fire experts that were not present in the BLM and USFS datasets. Fires that occur on private lands are generally recorded on paper maps and have not been consistently included in federal agency GIS datasets. Additional fire locations identified during the interviews with local fire personnel were recorded on the field maps where possible and added to the project wildfire perimeter dataset.
In addition to the fire perimeter information, point data for all fire ignitions within Nevada from 1980 to 2003 was obtained from the National Interagency Fire Center (NIFC) database in Boise, Idaho. This dataset includes an ignition point coordinate and an acreage component as reported to NIFC through a variety of agencies. This data is summarized in Table 3-2, and provides the ignition point locations for the maps in this report. In many cases, the ignition point location is only accurate to within the section. In such cases, the point coordinate is located in the section center on the maps.
The wildfire history and ignition history data were used to formulate risk ratings and to develop recommendations specific to areas that have been repeatedly impacted by wildland fires. Observations made from the RCI Project Team and comments from local fire agency personnel were also used to develop recommendations in areas without recent wildfire activity where a significant buildup of fuels or expansion of urban development into the interface area represents a growing risk.
The wildland-urban interface is the place where homes and wildland meet. This project focuses on identifying risks and hazards in the wildland-urban interface areas countywide by assessing each community individually. Site-specific information for each community was collected during field visits conducted between July 12 and July 15, 2004. The predominant conditions recorded during these site visits were used as the basis for the Community Risk and Hazard Assessment ratings.
Fire Specialists on the RCI Project Team assigned an ignition risk rating of low, moderate, or high to each community assessed. This rating is based on four sources of information: interpretation of the historical record of ignition patterns and fire polygons provided by the National Interagency Fire Center, Bureau of Land Management, and US Forest Service databases; interviews with local fire department personnel and local area Fire Management Officers; field visits to each community; and the professional judgment of the Fire Specialists on the RCI Project Team based on their experience with wildland fire ignitions in Nevada.
The Community Risk/Hazard Assessments were completed using methodology outlined in the Draft Community Wildland Fire Assessment For Existing and Planned Wildland Residential Interface Developments in Nevada. This system assigns hazard ratings of low through extreme based on the scoring system shown in Table 2-2 and detailed in Appendix B.
|Low Hazard||< 41|
To arrive at a score for the community, five primary factors that affect potential fire hazard were assessed: community design, construction materials, defensible space, fire suppression capabilities, and physical conditions that affect fire behavior such as fuel loading and topography. A description of each of these factors and their relative importance in developing the overall score for the community is provided below. Individual community score sheets presenting the point values assigned to each element in the hazard assessment are provided at the end of each community assessment.
Aspects of community design account for 26 percent of the total hazard score. Many aspects of community design can be modified to make a community more fire safe. Factors considered include:
The type of materials used for building construction account for 16 percent of the total assessment score. While it is not feasible to expect all structures in the wildland/urban interface area to be rebuilt with non-combustible materials, there are steps that can be taken to address specific elements that strongly affect structure ignitability in the interface area. Factors considered in the assessment include:
Defensible space accounts for 16 percent of the assessment score. The density and type of fuel around a home determines the potential fire exposure and the potential for damage to the home. A greater volume of trees, shrubs, dry weeds and grass, woodpiles, and other combustible materials near the home will ignite more readily, produce more intense heat during a fire, and increase the threat of losing the home. Defensible space is one of the factors that homeowners can most easily manipulate in order to improve the chances that a home or other property avoids damage or complete loss from a wildfire.
The availability and capability of fire suppression resources account for 16 percent of the total assessment score. Knowledge of the capabilities or limitations of the fire suppression resources in a community can help the residents take action to maximize the resources available. Factors considered in the assessment include:
The physical conditions that influence fire behavior account for 26 percent of the hazard rating. Physical conditions include slope, aspect, topography, fuel type, and fuel density. With the exception of changes to the fuel composition, the physical conditions in and around a community cannot be altered to make the community more fire safe. Therefore, an understanding of how these physical conditions can influence the behavior of a fire is essential to planning effective preparedness activities such as fuel reduction treatments. Physical conditions considered in the assessment include:
Fuel hazard maps were initially generated by the Bureau of Land Management Nevada and Utah State Offices using wildfire hazard delineations derived from vegetation satellite data at 30-meter resolution (Nevada GAP Analysis Program). A total of 65 vegetation types were mapped statewide and reclassified into four wildfire hazard categories (low, moderate, high, and extreme) based on the anticipated fire behavior for each vegetation cover type. For example, pinyon-juniper cover types were generally rated as extreme fuel hazard, while low sagebrush cover types are were rated as low fuel hazards.
The RCI Project Team visited high and extreme hazard communities and verified the BLM fuel hazard information by comparing the hazard ratings on the existing fuel hazard map to vegetation, slope, and aspect conditions directly observed in the field. Where necessary, changes to the ratings were drawn on the maps and used to update the wildfire hazard potential layer of the project database. Hazard mapping in Humboldt County was completed for Denio, Grass Valley, Quinn River, and Winnemucca.
Fire Specialists on the RCI Project Team described the worst-case wildfire scenarios included in this evaluation based on their analyses of the severe fire behavior that could occur given a set of weather conditions, observed fuel load conditions, slope, aspect, and minimal fire suppression resources. The drought conditions and dry vegetation in combination with steep slopes or high winds can create a situation in which the worst-case scenario can occur. The worst-case scenario does not describe the most likely outcome of a wildfire event in the interface, but it does illustrate the potential for damage if a given set of conditions were to occur simultaneously. The worst-case scenarios are described in this document for public education purposes and are part of the basis for the fuel reduction recommendations.
The RCI Project Team interviewed local fire department personnel and local fire management officers to obtain information on wildfire training, emergency response time, personnel and equipment capability and availability, evacuation plans, pre-attack plans, and estimates of possible worst-case scenarios. Local fire personnel reviewed maps showing the history of wildfires to ensure that local information on wildfires was included. A list of fire agency personnel contacted for information used in the assessments is included in Appendix D.
A wide variety of treatments and alternative measures can be used to reduce ignition risks, mitigate fire hazards, and promote fire safe communities. Proposed recommendations typically include physical removal or reduction of flammable vegetation, increased community awareness of the risk of fires and how to reduce those risks, and coordination among fire suppression agencies to optimize efforts and use of resources. The RCI Project Team met repeatedly to analyze community risks, treatment alternatives, and treatment benefits. Treatment recommendations to reduce existing risks and hazards were formulated based upon professional experience, the community hazard score, and information from published references such as Living With Fire and FIREWISE resources (National Fire Plan website, FIREWISE website, Nevada Cooperative Education publications). The recommendations included in this report are considered high priorities for individual communities and are presented in a relative order of importance.