Wildfire Risk to Communities Building Exposure (Image Service)

The data included in this publication depict components of wildfire risk specifically for populated areas in the United States. These datasets represent where people live in the United States and the in situ risk from wildfire, i.e., the risk at the location where the adverse effects take place. National wildfire hazard datasets of annual burn probability and fire intensity, generated by the USDA Forest Service, Rocky Mountain Research Station and Pyrologix LLC, form the foundation of the Wildfire Risk to Communities data. Vegetation and wildland fuels data from LANDFIRE 2020 (version 2.2.0) were used as input to two different but related geospatial fire simulation systems. Annual burn probability was produced with the USFS geospatial fire simulator (FSim) at a relatively coarse cell size of 270 meters (m). To bring the burn probability raster data down to a finer resolution more useful for assessing hazard and risk to communities, we upsampled them to the native 30 m resolution of the LANDFIRE fuel and vegetation data. In this upsampling process, we also spread values of modeled burn probability into developed areas represented in LANDFIRE fuels data as non-burnable. Burn probability rasters represent landscape conditions as of the end of 2020. Fire intensity characteristics were modeled at 30 m resolution using a process that performs a comprehensive set of FlamMap runs spanning the full range of weather-related characteristics that occur during a fire season and then integrates those runs into a variety of results based on the likelihood of those weather types occurring. Before the fire intensity modeling, the LANDFIRE 2020 data were updated to reflect fuels disturbances occurring in 2021 and 2022. As such, the fire intensity datasets represent landscape conditions as of the end of 2022. The data products in this publication that represent where people live, reflect 2021 estimates of housing unit and population counts from the U.S. Census Bureau, combined with building footprint data from Onegeo and USA Structures, both reflecting 2022 conditions. The specific raster datasets included in this publication include: Building Count: Building Count is a 30-m raster representing the count of buildings in the building footprint dataset located within each 30-m pixel. Building Density: Building Density is a 30-m raster representing the density of buildings in the building footprint dataset (buildings per square kilometer [km²]). Building Coverage: Building Coverage is a 30-m raster depicting the percentage of habitable land area covered by building footprints. Population Count (PopCount): PopCount is a 30-m raster with pixel values representing residential population count (persons) in each pixel. Population Density (PopDen): PopDen is a 30-m raster of residential population density (people/km²). Housing Unit Count (HUCount): HUCount is a 30-m raster representing the number of housing units in each pixel. Housing Unit Density (HUDen): HUDen is a 30-m raster of housing-unit density (housing units/km²). Housing Unit Exposure (HUExposure): HUExposure is a 30-m raster that represents the expected number of housing units within a pixel potentially exposed to wildfire in a year. This is a long-term annual average and not intended to represent the actual number of housing units exposed in any specific year. Housing Unit Impact (HUImpact): HUImpact is a 30-m raster that represents the relative potential impact of fire to housing units at any pixel, if a fire were to occur. It is an index that incorporates the general consequences of fire on a home as a function of fire intensity and uses flame length probabilities from wildfire modeling to capture likely intensity of fire. Housing Unit Risk (HURisk): HURisk is a 30-m raster that integrates all four primary elements of wildfire risk - likelihood, intensity, susceptibility, and exposure - on pixels where housing unit density is greater than zero. Additional methodology documentation is provided with the data publication download. Metadata and Downloads: (https://www.fs.usda.gov/rds/archive/catalog/RDS-2020-0060-2). Note: Pixel values in this image service have been altered from the original raster dataset due to data requirements in web services. The service is intended primarily for data visualization. Relative values and spatial patterns have been largely preserved in the service, but users are encouraged to download the source data for quantitative analysis.本出版物收录的数据专门针对美国人口聚居区域，展示野火风险相关要素。此类数据集涵盖美国人口居住区域分布，以及野火的原位风险——即负面影响发生地点处的实际风险。本社区野火风险数据集的基础，为美国农业部林务局（United States Department of Agriculture Forest Service，缩写USFS）落基山研究站与Pyrologix有限责任公司生成的年度燃烧概率与火强度全国野火危险性数据集。 本研究以LANDFIRE 2020（版本2.2.0）提供的植被与野外燃料数据，作为两类同源但相异的地理空间火灾模拟系统的输入参数。研究团队采用美国林务局地理空间火灾模拟器（FSim）生成年度燃烧概率，初始网格分辨率相对较粗，为270米。为将燃烧概率栅格数据提升至更适用于社区危险性与风险评估的更高分辨率，我们将其重采样至LANDFIRE燃料与植被数据原生的30米分辨率。在此重采样过程中，我们同时将模拟得到的燃烧概率值，拓展至LANDFIRE燃料数据中标记为不可燃的建成区。上述燃烧概率栅格数据反映的是2020年末的景观状况。 火强度特征以30米分辨率开展建模，具体流程为：全面运行FlamMap模拟，覆盖火灾季内所有气象相关特征的取值范围，随后依据各类气象情景的发生概率，将模拟结果整合为多类输出产品。在开展火强度建模前，我们已更新LANDFIRE 2020数据，以反映2021年与2022年发生的燃料扰动情况。因此，本次的火强度数据集反映的是2022年末的景观状况。 本出版物中用于展示人口居住分布的数据产品，整合了美国人口普查局（U.S. Census Bureau）2021年的住房单元与人口计数估算数据，以及Onegeo与USA Structures提供的建筑占地面积（building footprint）数据，两类数据均反映2022年的现状。 本出版物收录的具体栅格数据集如下： 1. 建筑数量（Building Count）：该30米分辨率栅格用于表征每个30米像素范围内，建筑占地面积数据集中对应的建筑物总数量。 2. 建筑密度（Building Density）：该30米分辨率栅格用于表征建筑占地面积数据集中的建筑密度，单位为建筑物数/平方千米（km²）。 3. 建筑覆盖率（Building Coverage）：该30米分辨率栅格用于展示建筑占地面积覆盖的可居住土地面积百分比。 4. 人口总数（Population Count, PopCount）：该30米分辨率栅格的像素值代表每个像素内的居住人口数，单位为人。 5. 人口密度（Population Density, PopDen）：该30米分辨率栅格的像素值代表居住人口密度，单位为人/平方千米（km²）。 6. 住房单元总数（Housing Unit Count, HUCount）：该30米分辨率栅格用于表征每个像素内的住房单元总数量。 7. 住房单元密度（Housing Unit Density, HUDen）：该30米分辨率栅格用于表征住房单元密度，单位为住房单元数/平方千米（km²）。 8. 住房单元暴露量（Housing Unit Exposure, HUExposure）：该30米分辨率栅格用于表征单个像素内，每年潜在遭受野火影响的住房单元预期数量。该指标为长期年度平均值，不代表任意特定年份实际遭受暴露的住房单元数量。 9. 住房单元影响程度（Housing Unit Impact, HUImpact）：该30米分辨率栅格用于表征若某像素区域发生火灾时，火灾对住房单元的相对潜在影响程度。该指数综合考虑了火灾强度对住宅的一般影响后果，并结合野火建模得到的火焰长度概率，以表征火灾的潜在强度。 10. 住房单元野火风险（Housing Unit Risk, HURisk）：该30米分辨率栅格整合了野火风险的四大核心要素——发生概率、强度、易损性与暴露量，仅覆盖住房密度大于0的像素区域。 本数据出版物的下载包中附带了额外的方法学文档。 元数据与下载链接：(https://www.fs.usda.gov/rds/archive/catalog/RDS-2020-0060-2) 注意：由于Web服务的数据需求，本影像服务的像素值已相较于原始栅格数据集进行调整。该服务主要用于数据可视化，其保留了原始数据的相对数值与空间分布格局，但建议用户下载原始源数据以开展定量分析。