Following wildfire, mountainous areas of the western United States are susceptible to enhanced runoff and erosion and an increased vulnerability to debris flow during intense rainfall. Convective storms that can generate debris flows in recently burned areas may occur during or immediately after the wildfire, leaving insufficient time for development and implementation of risk mitigation strategies. We present a method for estimating post-fire debris-flow hazards prior to wildfire using historical data to define the range of potential fire severity for a given location based on the statistical distribution of severity metrics obtained from remote sensing. Estimates of debris-flow likelihood, magnitude and triggering rainfall threshold based upon the statistically simulated fire severity data provide hazard predictions consistent with those calculated from fire severity data collected after wildfire. Simulated fire severity data also produce hazard estimates that replicate observed debris-flow occurrence, rainfall conditions, and magnitude at a monitored site in the San Gabriel Mountains of southern California. Future applications of this method should rely upon a range of potential fire severity scenarios for improved pre-fire estimates of debris-flow hazard. The method presented here is also applicable to modeling other post-fire hazards, such as flooding and erosion risk, and for quantifying historic trends in fire severity in a changing climate. This release contains the data used to derive the historical distributions of fire severity, including a) the data used to derive a Weibull cumulative distribution function to historical measures of the differenced normalized burn ratio for fires >= 4 square kilometers (1000 acres) that burned between 2001 and 2014 in the western United States, b) the shape and scale parameters for the Weibull cumulative distribution function for every class of existing vegetation type, and the statistics describing goodness-of-fit of the Weibull distribution to these data, and c) the data used to determine the BARC4 threshold defining the break between pixels burned at low and moderate or high severity.

These data were used to examine how post-fire sedimentation might change in western USA watersheds with future fire from the decade of 2001-10 through 2041-50. The data include previously published projections (Hawbaker and Zhu, 2012a, b) of areas burned by future wildfires for several climate change scenarios and general circulation models (GCMs) that we summarized for 471 watersheds of the western USA. The data also include previously published predictions (Miller et al., 2011) of first year post-fire hillslope soil erosion from GeoWEPP that we summarized for 471 watersheds of the western USA. We synthesized these summarized data in order to project sediment yield from future fires for 471 watersheds through the year 2050 at the hydrologic unit 8 (HUC8) scale. The detailed methods, results, and original data sources (i.e.: Hawbaker and Zhu, 2012a, b; Miller et al., 2011) were reported in the manuscript.

These data were used to examine how post-fire sedimentation might change in western USA watersheds with future fire from the decade of 2001-10 through 2041-50. The data include previously published projections (Hawbaker and Zhu, 2012a, b) of areas burned by future wildfires for several climate change scenarios and general circulation models (GCMs) that we summarized for 471 watersheds of the western USA. The data also include previously published predictions (Miller et al., 2011) of first year post-fire hillslope soil erosion from GeoWEPP that we summarized for 471 watersheds of the western USA. We synthesized these summarized data in order to project sediment yield from future fires for 471 watersheds through the year 2050 at the hydrologic unit 8 (HUC8) scale. The detailed methods, results, and original data sources (i.e.: Hawbaker and Zhu, 2012a, b; Miller et al., 2011) were reported in the manuscript.

These data were used to examine how post-fire sedimentation might change in western USA watersheds with future fire from the decade of 2001-10 through 2041-50. The data include previously published projections (Hawbaker and Zhu, 2012a, b) of areas burned by future wildfires for several climate change scenarios and general circulation models (GCMs) that we summarized for 471 watersheds of the western USA. The data also include previously published predictions (Miller et al., 2011) of first year post-fire hillslope soil erosion from GeoWEPP that we summarized for 471 watersheds of the western USA. We synthesized these summarized data in order to project sediment yield from future fires for 471 watersheds through the year 2050 at the hydrologic unit 8 (HUC8) scale. The detailed methods, results, and original data sources (i.e.: Hawbaker and Zhu, 2012a, b; Miller et al., 2011) were reported in the manuscript.

These data were used to examine how post-fire sedimentation might change in western USA watersheds with future fire from the decade of 2001-10 through 2041-50. The data include previously published projections (Hawbaker and Zhu, 2012a, b) of areas burned by future wildfires for several climate change scenarios and general circulation models (GCMs) that we summarized for 471 watersheds of the western USA. The data also include previously published predictions (Miller et al., 2011) of first year post-fire hillslope soil erosion from GeoWEPP that we summarized for 471 watersheds of the western USA. We synthesized these summarized data in order to project sediment yield from future fires for 471 watersheds through the year 2050 at the hydrologic unit 8 (HUC8) scale. The detailed methods, results, and original data sources (i.e.: Hawbaker and Zhu, 2012a, b; Miller et al., 2011) were reported in the manuscript.

This dataset represents 25 parallel longitudinal profiles that were extracted from terrestrial lidar point clouds taken during six survey periods. The six lidar surveys were conducted between 7 October 2010 and 8 October 2013. Over that time a colluvial hollow eroded into a fluvial channel. The longitudinal profiles show the topography of the colluvial hollow for each survey period. The width of the original colluvial hollow was approximately 1.25 m, and a longitudinal profile was extracted every 5 cm for the entire length of the hollow, resulting in 25 parallel longitudinal profiles. These data can be used to observe the transition of the colluvial hollow to a fluvial channel and furthermore they show the development of alternating steps and plunge pools. Within each of the 25 files, the column header describes the point number of the longitudinal profile, the distance downstream (meters), and the date of data collection. In addition, the file numbers represent profiles from west (1) to east (25).

This dataset represents 25 parallel longitudinal profiles that were extracted from terrestrial lidar point clouds taken during six survey periods. The six lidar surveys were conducted between 7 October 2010 and 8 October 2013. Over that time a colluvial hollow eroded into a fluvial channel. The longitudinal profiles show the topography of the colluvial hollow for each survey period. The width of the original colluvial hollow was approximately 1.25 m, and a longitudinal profile was extracted every 5 cm for the entire length of the hollow, resulting in 25 parallel longitudinal profiles. These data can be used to observe the transition of the colluvial hollow to a fluvial channel and furthermore they show the development of alternating steps and plunge pools. Within each of the 25 files, the column header describes the point number of the longitudinal profile, the distance downstream (meters), and the date of data collection. In addition, the file numbers represent profiles from west (1) to east (25).

The increase in wildfires, particularly in the western U.S., represents one of the greatest threats to multiple native ecosystems. Despite this threat, there is currently no central repository to store both past and current wildfire perimeter data. Currently, wildfire boundaries can only be found in disparate local or national datasets. These datasets are generally restricted to specific locations, fire sizes, or time periods. Our objective was to create a comprehensive national wildfire perimeter dataset by combining all freely available wildfire datasets that we could download. We combined and dissolved individual wildfire polygons from multiple datasets if they were in the same year and overlapped each other or were within 1km of the fire boundary. This combined dataset includes spatial summary statistics such as number of times burned, earliest fire of record, and most recent fire of record.

The increase in wildfires, particularly in the western U.S., represents one of the greatest threats to multiple native ecosystems. Despite this threat, there is currently no central repository to store both past and current wildfire perimeter data. Currently, wildfire boundaries can only be found in disparate local or national datasets. These datasets are generally restricted to specific locations, fire sizes, or time periods. Our objective was to create a comprehensive national wildfire perimeter dataset by combining all freely available wildfire datasets that we could download. We combined and dissolved individual wildfire polygons from multiple datasets if they were in the same year and overlapped each other or were within 1km of the fire boundary. This combined dataset includes spatial summary statistics such as number of times burned, earliest fire of record, and most recent fire of record.

Wildfire can substantially alter the hydrologic response of watersheds to rainfall, and debris-flow activity is the among the most destructive consequences of these events. To assist federal, state, and local agencies in planning for postfire hazards, the U.S. Geological Survey conducts debris-flow hazard assessments for recent wildfires.This item holds the postfire debris-flow hazard assessment for the Shelly fire event that began on or near 2024-07-03. Contents: Shapefiles.zip Zip archive of hazard modeling results. Includes shapefiles for the fire perimeter, stream segments, catchment basins, and outlet points. shl2024-field-descriptions.txt Descriptions of the shapefile data fields. shl2024-median-thresholds.csv Table of median rainfall thresholds as calculated over the stream segments and catchment basins. shl2024-metadata.txt Auxiliary metadata about the fire event and implementation of the hazard assessment. Methods: The hazard assessment was designed to implement: * The "M1" debris-flow likelihood model of Staley and others (2017) * The "emergency" potential sediment volume model of Gartner and others (2014) * The debris-flow combined hazard classification scheme of Cannon and others (2010) The assessment was produced by USGS personnel running the beta version of the ocelote package. Operational personnel may have also modified stream network delineation and modeling parameters in order to ensure quality. The beta version is represented by the ocelote commits prior to the v1.0.0 release. The ocelote source repository can be found here: https://code.usgs.gov/ghsc/lhp/ocelote References: Cannon, S. H., Gartner, J. E., Rupert, M. G., Michael, J. A., Rea, A. H., and Parrett, C. (2010). Predicting the probability and volume of postwildfire debris flows in the intermountain western United States. Bulletin, 122(1-2), 127-144. Gartner, J. E., Cannon, S. H., and Santi, P. M. (2014). Empirical models for predicting volumes of sediment deposited by debris flows and sediment-laden floods in the transverse ranges of southern California. Engineering Geology, 176, 45-56. Staley, D. M., Negri, J. A., Kean, J. W., Laber, J. L., Tillery, A. C., and Youberg, A. M. (2017). Prediction of spatially explicit rainfall intensity–duration thresholds for post-fire debris-flow generation in the western United States. Geomorphology, 278, 149-162.