A Pilot Wildfire Risk Assessment for Texas

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The purpose of the Texas Wildfire Risk Assessment (TWRA) is to provide foundational information about wildfire hazard across the geographic area. Such information supports wildfire response, regional fuel management planning, and revisions to land and resource management plans. A wildfire risk assessment is a quantitative analysis of the assets and resources across a specific landscape and how they are potentially impacted by wildfire. The TWRA analysis considers:

  • likelihood of a fire burning
  • the intensity of a fire if one should occur
  • the exposure of assets and resources based on their locations, and
  • the susceptibility of those assets and resources to wildfire.

To manage wildfire across that state, accurate wildfire risk data must be available to inform land and fire management strategies. These risk outputs can be used to aid in the planning, prioritization, and implementation of prevention and mitigation activities. In addition, the risk data can be used to support fire operations in response to wildfire incidents by identifying those assets and resources most susceptible to fire.

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A Pilot Wildfire Risk Assessment for California

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The pilot effort to assess risk to certain highly valued resources and assets is an extension of the California All-Lands Hazard Assessment, a project funded by the USDA Forest Service that produced fuel and wildfire hazard information for the year 2020. Since that time, the wildfire hazard data has been updated to reflectthe historic wildfire events of 2020 that impacted millions of acres across the state.

As a pilot assessment, the set of Highly Valued Resources and Assets (HVRA) was limited to housing, critical infrastructure, and surface drinking water — those most commonly identified HVRA for wildfire risk assessments and generally most representative of risk to communities. These HVRA were identified at the outset of the project as a baseline assessment of wildfire risk that can be expanded with a larger set of HVRA as additional funding and projects are identified. In February 2022, a small group of interagency stakeholders met virtually to review and edit HVRA characterization inputs needed to calculate wildfire risk. Their task was to review a preliminary set of Response Functions that characterized each HVRA’s response to fires of different intensity levels, to assign Relative Importance values which establish the ranking of the primary HVRA relative to each other, and agree on a common set of inputs needed to calculate wildfire effects analyses described in this report.

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Wildfire Risk for All Lands in Colorado

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The effort to produce a quantitative wildfire risk assessment across all land ownerships in Colorado began in February 2019 when the Rocky Mountain Region of the USDA Forest Service contracted with Pyrologix to calibrate and update a fuelscape, conduct wildfire hazard modeling, characterize the response of multiple Highly Valued Resources and Assets (HVRA) to wildfire, and complete wildfire risk calculations. Though this effort was initiated by the Forest Service, care was taken to include the considerations of multiple agencies and stakeholder groups within the State.

The COAL wildfire risk assessment project consisted of three parts: fuelscape update, wildfire hazard assessment, and wildfire risk assessment. Reports documenting the methods and results of the updated fuelscape(1) and wildfire hazard products(2) are available for download.

We leveraged LANDFIRE 2016 Remap 2.0.0 (LF Remap) data to generate a current condition fuelscape for this Colorado All-Lands (COAL) statewide assessment. The fuelscape was updated for recent disturbances and calibrated to reflect the fire behavior potential observed in recent historical wildfire events. LF Remap was released in the spring of 2019 with significant improvements over previous versions of LANDFIRE, including the use of new satellite imagery and continuous vegetation cover and height classifications(3) .The COAL fuelscape was first produced for use in the 2020 fire season and wildfire hazard modeling using this fuelscape had begun. However, the unprecedented wildfire season of 2020 had a significant impact on the fuelscape used to represent the “current conditions.” In light of this, Pyrologix generated a new fuelscape to incorporate the fuel changes from the 2020 wildfires and bring the fuelscape forward to a “2021 capable” timeframe.

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Wildfire Risk Across the Eastern Region

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In April 2019, the Eastern Region of the U.S. Forest Service contracted with Pyrologix to conduct a spatial wildfire hazard assessment across all land ownerships in the Eastern Region states. The initial focus of the project was to conduct a wildfire risk assessment for homes, critical infrastructure, and water resources in the Eastern Region. Project delays, largely due to COVID-19, presented an opportunity to update the fuelscape using the LANDFIRE Remap (version 2.0.0) data, completed for all geographic areas in the Eastern Region in July of 2020. The delays provided the opportunity to update the fuelscape and to leverage recent improvements in fire intensity modeling. With the incorporation of these project additions, the Eastern Region assessment consisted of four parts: fuelscape update, wildfire hazard assessment, wildfire risk assessment, and summary of wildfire risk to the most-exposed communities in each state.

Initial fuel calibration efforts were conducted with LANDFIRE 2014 (version 1.4.0) data. In March 2019, Pyrologix led three in-person fuel calibration workshops hosted by the Region and attended by a wide array of local, state, and federal specialists in the fields of fuel characterization, fire ecology, and fire behavior modeling. These workshops were hosted in three locations to facilitate attendance across the large geographic area: Albany, NY; Martinsville, IN; and Milwaukee, WI. The information gathered in those workshops was used to calibrate the LANDFIRE 2014 fuelscape initially, and those edits were brought forward to calibrate the LANDFIRE Remap data, beginning in the fall of 2020.

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Chugach All-Lands Wildfire Risk Assessment: Method and Results

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The purpose of the Chugach All-Lands Wildfire Risk Assessment (hereafter called ARRA1 ) is to provide foundational information about wildfire hazard and risk to highly valued resources and assets for the Chugach National Forest and surrounding areas in Southcentral Alaska. Such information supports wildfire response, fuel management planning, and revisions to land and resource management plans. A wildfire risk assessment is a quantitative analysis of the assets and resources across a specific landscape and how they are potentially impacted by wildfire. The ARRA analysis considers several different components, each resolved spatially across the region, including:

  • likelihood of a fire burning
  • the intensity of a fire if one should occur
  • the exposure of assets and resources based on their locations
  • the susceptibility of those assets and resources to wildfire.

Assets are human-made features, such as commercial structures, critical facilities, housing, etc., that have specific importance or value. Resources are natural features, such as wildlife habitat, vegetation type, or water, etc. These also have specific importance or value. Generally, the term “values at risk” has been used to describe both assets and resources. For the ARRA assessment, the term Highly Valued Resources and Assets (HVRA) is used to describe what has previously been labeled values at risk. There are two reasons for this change in terminology. First, resources and assets are not themselves “values” in any way that term is conventionally defined—they have value (importance). Second, while resources and assets may be exposed to wildfire, they are not necessarily “at-risk”—that is the purpose of the assessment.

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Wildfire Risk to California Communities

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We assessed wildfire risk to homes and communities in California as part of a larger assessment of wildfire hazard across the state. In July 2019 the Pacific Southwest Region of the U.S. Forest Service contracted with Pyrologix to conduct a spatial wildfire hazard assessment across all land ownerships. This summary of wildfire risk to California communities is the third and final part of the larger wildfire hazard assessment.

The concept of summarizing wildfire risk to housing units within a set of pre-defined communities is well-established. In 2018, Pyrologix produced a report titled “Exposure of human communities to wildfire in the Pacific Northwest” for the Pacific Northwest Region of the U.S. Forest Service(1) . That report identified the most at-risk communities in terms of 1) the mean risk to all housing units in a community, and 2) the cumulative risk within the community, which increases with community size (population). Following that analysis, the Wildfire Risk to Communities(2) project was established by the U.S. Forest Service; it produced a nationwide summary of wildfire risk to communities by generating nationally consistent web maps, summary statistics, downloadable spatial data and tables, and more for the conterminous U.S., Alaska, and Hawaii.

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Region 2–San Juan National Forest Quantitative Wildfire Risk Assessment: Methods and Results

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The purpose of the Region 2: San Juan National Forest Risk Assessment (R2SJ) is to provide foundational information about wildfire hazard and risk to highly valued resources and assets across the geographic area. Such information supports wildfires, fuel management planning decisions, and revisions to land and resource management plans. A wildfire risk assessment is a quantitative analysis of the assets and resources across a specific landscape and how they are potentially impacted by wildfire. The R2SJ analysis considers several different components, each resolved spatially across the Forest, including:

  • likelihood of a fire burning,
  • the intensity of a fire if one should occur,
  • the exposure of assets and resources based on their locations, and
  • the susceptibility of those assets and resources to wildfire.

Assets are human-made features, such as commercial structures, critical facilities, housing, etc., that have a specific importance or value. Resources are natural features, such as wildlife habitat, federally threatened and endangered plant or animal species, etc. These also have a specific importance or value. Generally, the term “values at risk” has previously been used to describe both assets and resources. For R2SJ, the term Highly Valued Resources and Assets (HVRA) is used to describe what has previously been labeled values at risk. There are two reasons for this change in terminology. First, resources and assets are not themselves “values” in any way that term is conventionally defined—they have value (importance). Second, while resources and assets may be exposed to wildfire, they are not necessarily “at risk”—that is the purpose of the assessment.

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Region 2–Rio Grande National Forest Quantitative Wildfire Risk Assessment: Methods and Results

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The purpose of the Region 2: Rio Grande National Forest Risk Assessment (R2RG) is to provide foundational information about wildfire hazard and risk to highly valued resources and assets across the geographic area. Such information supports wildfires, fuel management planning decisions, and revisions to land and resource management plans. A wildfire risk assessment is a quantitative analysis of the assets and resources across a specific landscape and how they are potentially impacted by wildfire. The R2RG analysis considers several different components, each resolved spatially across the Forest, including:

  • likelihood of a fire burning,
  • the intensity of a fire if one should occur,
  • the exposure of assets and resources based on their locations, and
  • the susceptibility of those assets and resources to wildfire.

Assets are human-made features, such as commercial structures, critical facilities, housing, etc., that have a specific importance or value. Resources are natural features, such as wildlife habitat, federally threatened and endangered plant or animal species, etc. These also have a specific importance or value. Generally, the term “values at risk” has previously been used to describe both assets and resources. For R2RG, the term Highly Valued Resources and Assets (HVRA) is used to describe what has previously been labeled values at risk. There are two reasons for this change in terminology. First, resources and assets are not themselves “values” in any way that term is conventionally defined—they have value (importance). Second, while resources and assets may be exposed to wildfire, they are not necessarily “at risk”—that is the purpose of the assessment.

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USFS Region 5–Southern California Quantitative Wildfire Risk Assessment: Methods and Results

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The purpose of the USFS Region 5 Southern California Wildfire Risk Assessment (SCRA) is to provide foundational information about wildfire hazard and risk to highly valued resources and assets across the geographic area. Such information supports wildfires, regional fuel management planning decisions, and revisions to land and resource management plans. A wildfire risk assessment is a quantitative analysis of the assets and resources across a specific landscape and how they are potentially impacted by wildfire. The SCRA analysis considers several different components, each resolved spatially across the region, including:

  • likelihood of a fire burning,
  • the intensity of a fire if one should occur,
  • the exposure of assets and resources based on their locations, and
  • the susceptibility of those assets and resources to wildfire.

Assets are human-made features, such as commercial structures, critical facilities, housing, etc., that have a specific importance or value. Resources are natural features, such as wildlife habitat, federally threatened and endangered plant or animal species, etc. These also have a specific importance or value. Generally, the term “values at risk” has previously been used to describe both assets and resources. For SCRA, the term Highly Valued Resources and Assets (HVRA) is used to describe what has previously been labeled values at risk. There are two reasons for this change in terminology. First, resources and assets are not themselves “values” in any way that term is conventionally defined—they have value (importance). Second, while resources and assets may be exposed to wildfire, they are not necessarily “at risk”—that is the purpose of the assessment.

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Northern Region Wildfire Risk Assessment: methods and results

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The purpose of the USFS Northern Region Wildfire Risk Assessment (NoRRA) is to provide foundational information about wildfire hazard and risk to highly valued resources and assets across the Region. Such information supports regional fuel management planning decisions as well as revisions to land and resource management plans. A wildfire risk assessment is a quantitative analysis of the assets and resources across a specific landscape and how they are potentially impacted by wildfire. The NoRRA analysis considers several different components, each resolved spatially across the Region, including:

  • likelihood of a fire burning,
  • the intensity of a fire if one should occur,
  • the exposure of assets and resources based on their locations, and
  • the susceptibility of those assets and resources to wildfire

Assets are man-made features, such as commercial structures, critical facilities, housing, etc., that have a specific importance or value. Resources are natural features, such as wildlife habitat, federally threatened and endangered species (wildlife and vegetation), etc. These also have a specific importance or value. Generally, the term “values at risk” has previously been used to describe both assets and resources. For NoRRA, the term Highly Valued Resources and Assets (HVRA) is used to describe what has previously been labeled values at risk. There are two reasons for this change in terminology. First, resources and assets are not themselves “values” in any way that term is conventionally defined—they have value (importance). Second, while resources and assets may be exposed to wildfire, they are not necessarily “at risk”—that is the purpose of the assessment.

Read the full report