Summary This data release is an inventory of runoff-generated postfire debris flows compiled from 17 burn areas across five western U.S. states. Debris-flow data from the following fires are included: - Arizona: 2017 Pinal and 2019 Woodbury Fires - California: 2020 Apple, 2020 Bond, 2015 Butte, 2020 El Dorado, 2014 El Portal, 2018 Ferguson, 2016 Fish (San Gabriel Complex), 2011 Motor, and 2017 Thomas Fires - Colorado: 2020 Cameron Peak and 2018 Spring Creek Fires - New Mexico: 2018 Buzzard Fire - Washington: 2021 Cedar Creek, 2021 Cub Creek 2, and 2021 Muckamuck Fires The included table, “Combined_Inventory.csv”, contains debris-flow records represented as “1” or “0”, indicating whether a debris flow did occur or did not occur, respectively, in response to a given storm. In addition, for each observation, the corresponding fire name, observation location, storm date, and rainfall intensities are included. The “README.txt” file describes the fields (including units) for “Combined_Inventory.csv” in more detail. "0" values in the "Response" column indicate that no debris flow was observed, but a hydrologic response with lower sediment content may or may not have occurred. Assembling these data in a unified format involved a combination of compiling data from published sources and synthesizing new debris-flow records from observations made by US Geological Survey staff and partners. All records in the included file, "Combined_inventory.csv", are credited according to the individuals or publications that provided the observation information in the column labeled “ObservationSource”. To the best of our knowledge, all records included here correspond to debris flows generated by runoff, not by other mechanisms. These records have only limited spatial and temporal extent: they should not be taken as a comprehensive record of the hydrologic response in every catchment in response to every postfire storm. Fields with value “-9999” indicate that data are not available or do not exist. Data Credits Special thanks go to many colleagues who provided or helped to assemble debris-flow observation and/or rainfall data, including: Ann Youberg (Arizona Geological Survey); Paul Burgess, Jeremy Lancaster, Don Lindsay, John Oswald, and Brian Swanson (California Geological Survey); Chad Neptune (California State Water Resources Control Board); Stephanie Kampf, Lee MacDonald, Megan Sears, and Ellen Wohl (Colorado State University); Luke McGuire (University of Arizona); Maya Daurio (University of British Columbia); Laura Hempel, Jason Kean, Francis Rengers, Brittany Selander, and Matthew Thomas (U.S. Geological Survey); and Mitchell Allen and Kate Mickelson (Washington Geological Survey).

This data release is a field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm. The “README.txt” file describes the fields for the “Inventory.csv” file. The “Chambers” and “Chips” rain gage data referenced in the inventory are included as: “Chambers-Oct2021-Storm.csv”, “Chambers-Jun2022-Storm.csv”, “Chips-Oct2021-Storm.csv”, and “Chips-Jun2022-Storm.csv.” The fields for the rain gage data, which includes the geographic locations of the gages, are also described in the “README.txt” file. Fields with value “-9999” indicate that data are not available or do not exist.

This data release is a field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm. The “README.txt” file describes the fields for the “Inventory.csv” file. The “Chambers” and “Chips” rain gage data referenced in the inventory are included as: “Chambers-Oct2021-Storm.csv”, “Chambers-Jun2022-Storm.csv”, “Chips-Oct2021-Storm.csv”, and “Chips-Jun2022-Storm.csv.” The fields for the rain gage data, which includes the geographic locations of the gages, are also described in the “README.txt” file. Fields with value “-9999” indicate that data are not available or do not exist.

This data release contains two debris-flow inventories summarizing observations from burned and unburned areas in the western Cascade Range of Oregon (OR). The burned inventory focuses on debris flows that occurred during the first two years after the 2020 Archie Creek, Holiday Farm, Beachie Creek/Lionshead, and Riverside fires (OR_field_observations.csv). The unburned inventory (1995-2022) focuses on debris flows in the same areas (excluding the Riverside Fire). The inventories are derived from field observations (OR_field_observations.csv) and aerial imagery (OR_imagery_observations.csv). They include mapped debris-flow initiation locations, descriptions of the inferred initiation process, other notable site characteristics, and rainfall data. Locations of debris flows observed after wildfires are also linked to USGS postfire debris-flow hazard assessments (USGS, 2022; Staley and others, 2017; Thomas and others 2023). Rainfall characteristics for each debris flow in the inventory are derived from the closest rainfall gage to an observed debris flow (gage_locations.csv). Peak rainfall rates during the known time window of debris-flow initiation are reported for durations of 15 minutes, 30 minutes, 60 minutes, 12 hours, 24 hours, 36 hours, and 48 hours. More detailed explanations of the headers for each of these csv files can be found within the README_csvname.txt file. References: Landslide Hazards Program. (n.d.). Emergency assessment of post-fire debris-flow hazards. U.S. Geological Survey. https://landslides.usgs.gov/hazards/postfire_debrisflow 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. https://doi.org/10.1016/j.geomorph.2016.10.019 Thomas, M. A., Kean, J. W., McCoy, S. W., Lindsay, D. N., Kostelnik, J., Cavagnaro, D. B., Rengers, F. K., East, A. E., Schwartz, J. Y., Smith, D. P., and Collins, B. D., 2023, Postfire hydrologic response along the Central California (USA) coast: insights for the emergency assessment of postfire debris-flow hazards. Landslides, 20, 2421-2436. https://doi.org/10.1007/s10346-023-02106-7

This data release contains two debris-flow inventories summarizing observations from burned and unburned areas in the western Cascade Range of Oregon (OR). The burned inventory focuses on debris flows that occurred during the first two years after the 2020 Archie Creek, Holiday Farm, Beachie Creek/Lionshead, and Riverside fires (OR_field_observations.csv). The unburned inventory (1995-2022) focuses on debris flows in the same areas (excluding the Riverside Fire). The inventories are derived from field observations (OR_field_observations.csv) and aerial imagery (OR_imagery_observations.csv). They include mapped debris-flow initiation locations, descriptions of the inferred initiation process, other notable site characteristics, and rainfall data. Locations of debris flows observed after wildfires are also linked to USGS postfire debris-flow hazard assessments (USGS, 2022; Staley and others, 2017; Thomas and others 2023). Rainfall characteristics for each debris flow in the inventory are derived from the closest rainfall gage to an observed debris flow (gage_locations.csv). Peak rainfall rates during the known time window of debris-flow initiation are reported for durations of 15 minutes, 30 minutes, 60 minutes, 12 hours, 24 hours, 36 hours, and 48 hours. More detailed explanations of the headers for each of these csv files can be found within the README_csvname.txt file. References: Landslide Hazards Program. (n.d.). Emergency assessment of post-fire debris-flow hazards. U.S. Geological Survey. https://landslides.usgs.gov/hazards/postfire_debrisflow 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. https://doi.org/10.1016/j.geomorph.2016.10.019 Thomas, M. A., Kean, J. W., McCoy, S. W., Lindsay, D. N., Kostelnik, J., Cavagnaro, D. B., Rengers, F. K., East, A. E., Schwartz, J. Y., Smith, D. P., and Collins, B. D., 2023, Postfire hydrologic response along the Central California (USA) coast: insights for the emergency assessment of postfire debris-flow hazards. Landslides, 20, 2421-2436. https://doi.org/10.1007/s10346-023-02106-7

This data release includes time-series data from a monitoring site located in a small (0.12 km2) drainage basin in the Las Lomas watershed in Los Angeles County, CA, USA. The site was established after the 2016 Fish Fire and recorded a series debris flows in the first winter after the fire. The station is located along the channel at the outlet of the study area (34 9’18.50”N, 117 56’41.33”W, WGS84). The data were collected between November 15, 2016 and February 23, 2017. The data include two types of time series: (1) continuous 1-minute time series of rainfall and flow stage recorded by a laser distance meter suspended over the channel (LasLomasContinuous.csv), and (2) 50-Hz time series of flow stage and flow-induced ground vibrations recorded by two geophones (LasLomasStorm.csv). The continuous file contains brief data gaps when the station was serviced, at which time the record of cumulative rainfall was reset to zero. The ground vibrations were measured by two 4.5 Hz vertical axis geophones (Geospace SNG 11D/PC902/OPEN-30m) located approximately 2 m from the channel bank. One geophone was located 6.4 m upstream from the laser distance meter. The second geophone was located 7.6 m downstream of the geophone. The geophone data is recorded in millivolts and the geophone constant is 32 Volts/(m/s). The equation for converting the laser distance measurements into flow stage above the bedrock in the channel is: Stage_laser (meters) = 4.320 meters – Distance_laser (millimeters) /1000. Time stamps are in Coordinated Universal Time (UTC). Details of this study are described in the journal article: Tang, H., McGuire, L.A., F.K. Rengers, Kean, J. W., Staley, D.M., and Smith, J.B. (2018), Evolution of debris flow initation mechanisms and sediment sources during a series of post-wildfire rainstorms, J. Geophys. Res., xxx, FYYYYY, doi:10.1029/2018JF004837.

This data release includes time-series data from a monitoring site located in a small (0.12 km2) drainage basin in the Las Lomas watershed in Los Angeles County, CA, USA. The site was established after the 2016 Fish Fire and recorded a series debris flows in the first winter after the fire. The station is located along the channel at the outlet of the study area (34 9’18.50”N, 117 56’41.33”W, WGS84). The data were collected between November 15, 2016 and February 23, 2017. The data include two types of time series: (1) continuous 1-minute time series of rainfall and flow stage recorded by a laser distance meter suspended over the channel (LasLomasContinuous.csv), and (2) 50-Hz time series of flow stage and flow-induced ground vibrations recorded by two geophones (LasLomasStorm.csv). The continuous file contains brief data gaps when the station was serviced, at which time the record of cumulative rainfall was reset to zero. The ground vibrations were measured by two 4.5 Hz vertical axis geophones (Geospace SNG 11D/PC902/OPEN-30m) located approximately 2 m from the channel bank. One geophone was located 6.4 m upstream from the laser distance meter. The second geophone was located 7.6 m downstream of the geophone. The geophone data is recorded in millivolts and the geophone constant is 32 Volts/(m/s). The equation for converting the laser distance measurements into flow stage above the bedrock in the channel is: Stage_laser (meters) = 4.320 meters – Distance_laser (millimeters) /1000. Time stamps are in Coordinated Universal Time (UTC). Details of this study are described in the journal article: Tang, H., McGuire, L.A., F.K. Rengers, Kean, J. W., Staley, D.M., and Smith, J.B. (2018), Evolution of debris flow initation mechanisms and sediment sources during a series of post-wildfire rainstorms, J. Geophys. Res., xxx, FYYYYY, doi:10.1029/2018JF004837.

This data release includes time-series data from a monitoring site located in a small drainage basin in the Arroyo Seco watershed in Los Angeles County, CA, USA (N3788964 E389956, UTM Zone 11, NAD83). The site was established after the 2009 Station Fire and recorded a series debris flows in the first winter after the fire. The data include three types of time-series: (1) 1-minute time series of rainfall, soil water content, channel bed pore pressure and temperature, and flow stage recorded by radar and laser distance meters (ArroyoSecoContinuous.csv); (2) 10-Hz time series of flow stage recorded by the laser distance meter during rain storms (ArroyoSecoStormLaser.csv), and (3) 2-second time series of rainfall and channel bed pore pressure and temperature during rain storms (ArroyoSecoStormPressureRain.csv). The laser and radar distance meters are suspended above the pore pressure sensor mounted in the bedrock of the channel. The equations for converting the distance measurements into flow stage above the pressure sensor (or stage of the stationary bed surface during times of no flow) are given by the equations Stage_laser (meters) = 2.107 meters – Distance_laser (meters), and Stage_radar (meters) = 2.156 meters – Distance_radar (feet)*0.3048 Details of this study are described in the journal article: Kean, J. W., D. M. Staley, and S. H. Cannon (2011), In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions, J. Geophys. Res., 116, F04019, doi:10.1029/2011JF002005.

Wildfires are increasing in size and severity due to warmer drought climate change combined with overstocked forests. Fire increases the likelihood of debris flows, posing significant threats to life, property, and water supplies. Post-fire debris flows are a substantial, increasing hazard in the Santa Fe Municipal Watershed and other similar forested watersheds across the western United States. The Santa Fe Municipal Watershed in northern New Mexico is of vital importance to the water supply for the city of Santa We conducted a debris-flow hazard assessment for the Santa Fe Municipal Watershed (SFMW) in north-central New Mexico. We modeled post-fire debris flow probability and volume in 103 sub-basins for 2-year, 5-year, and Probable Maximum Precipitation rainfalls following modeled low-, moderate-, and high-severity wildfires. Crown fire potential was modeled with FlamMap (Finney, 2006), after Tillery et al. (2014). To satisfy data input requirements of the debris flow model that includes burn severity classes (low, moderate, and high), the modeled crown fire activity was first converted to dNBR (French et al. 2008). This conversion was calibrated based on burn severities from the 2011 Pacheco Fire that burned in a nearby watershed (approximately 5 km north of the SFMW). Data files are numbered 1-5. Spatial files provided in this data release include: 1) polygon of the study area; 2) 103 sub-basins within the study area; 3) Thematic Burn Severity Mosaic for New Mexico in 2011; and 4) complete post-fire debris flow probability and volume data of every rainfall event and wildfire scenario for 103 sub-basins; and tabulated data provided in this data release include: 5) calculated burn severity percentages for Pacheco Canyon Fire.

Wildfires are increasing in size and severity due to warmer drought climate change combined with overstocked forests. Fire increases the likelihood of debris flows, posing significant threats to life, property, and water supplies. Post-fire debris flows are a substantial, increasing hazard in the Santa Fe Municipal Watershed and other similar forested watersheds across the western United States. The Santa Fe Municipal Watershed in northern New Mexico is of vital importance to the water supply for the city of Santa We conducted a debris-flow hazard assessment for the Santa Fe Municipal Watershed (SFMW) in north-central New Mexico. We modeled post-fire debris flow probability and volume in 103 sub-basins for 2-year, 5-year, and Probable Maximum Precipitation rainfalls following modeled low-, moderate-, and high-severity wildfires. Crown fire potential was modeled with FlamMap (Finney, 2006), after Tillery et al. (2014). To satisfy data input requirements of the debris flow model that includes burn severity classes (low, moderate, and high), the modeled crown fire activity was first converted to dNBR (French et al. 2008). This conversion was calibrated based on burn severities from the 2011 Pacheco Fire that burned in a nearby watershed (approximately 5 km north of the SFMW). Data files are numbered 1-5. Spatial files provided in this data release include: 1) polygon of the study area; 2) 103 sub-basins within the study area; 3) Thematic Burn Severity Mosaic for New Mexico in 2011; and 4) complete post-fire debris flow probability and volume data of every rainfall event and wildfire scenario for 103 sub-basins; and tabulated data provided in this data release include: 5) calculated burn severity percentages for Pacheco Canyon Fire.