Jonathan M. King Jaime Kostelnik Jason W. Kean 20240920 vector digital data https://doi.org/10.5066/P13GTMAX 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 Hill fire event that began on or near 2024-07-16. Contents: Shapefiles.zip Zip archive of hazard modeling results. Includes shapefiles for the fire perimeter, stream segments, catchment basins, and outlet points. hil2024-field-descriptions.txt Descriptions of the shapefile data fields. hil2024-median-thresholds.csv Table of median rainfall thresholds as calculated over the stream segments and catchment basins. hil2024-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. This assessments was produced in response to elevated debris-flow hazards following wildfire events, and is intended to assist federal, state, and local agencies in planning for postfire hazards. 20240716 Fire start date Complete None planned -123.699074 -123.6025 40.828056 40.746481 ISO 19115 Topic Category geoscientificInformation USGS information products data release USGS Thesaurus landslides hazards fires maps and atlases landslide susceptibility assessment hazard preparedness mathematical modeling USGS Metadata Identifier USGS:68c49328d4be021a00d8cccc Common geographic areas United States North America No access constraints. Please see 'Distribution Information' for details. These data are marked with a Creative Commons Zero v1.0 Universal (CC0-1.0) public domain dedication and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. U.S. Geological Survey, Landslide Hazards Program GHSC Data Steward GHSC Data Steward mailing and physical

1711 Illinois St

Golden CO 80401 US 3032738500 ghsc_metadata@usgs.gov BAER, GTAC, and EROS supported the collection of input datasets used to implement the hazard models. Beta versions of the ocelote codebase via Python 3.11. Assessments were reviewed by USGS personnel prior to publication. Personnel may have modified stream network delineation and modeling parameters in order to ensure quality. No formal logical tests were performed. The assessment results represent areas within or downstream of the fire perimeter, pursuant to the modeling criteria of the ocelote package. BAER Team 20240920 vector digital data Digital and/or Hardcopy 20240920 Assessment Date perimeter Used to define the burn area USGS National Map 1/3rd arc-second DEM 20240920 raster digital data https://www.sciencebase.gov/catalog/item/4f70aa9fe4b058caae3f8de5 Digital and/or Hardcopy 20240920 Assessment Date dem Used to compute flow pathways, slopes, and vertical relief. BAER Team 20240920 raster digital data Digital and/or Hardcopy 20240920 Assessment Date dnbr Informs the M1 likelihood model. BAER Team 20240920 raster digital data Digital and/or Hardcopy 20240920 Assessment Date severity Informs network delineation, the M1 likelihood model, and the volume model. STATSGO KFFACT 20240920 vector digital data https://www.sciencebase.gov/catalog/item/631405c5d34e36012efa3187 Digital and/or Hardcopy 20240920 Assessment Date kf Informs the M1 likelihood model. LANDFIRE 240EVT 20240920 raster digital data https://lfps.usgs.gov/api Digital and/or Hardcopy 20240920 Assessment Date evt Informs network delineation. Los Angeles County, CA 20240920 vector digital data https://pw.lacounty.gov/sur/nas/landbase/AGOL/Debris_Basin.gdb.zip Digital and/or Hardcopy 20240920 Assessment Date retainments Informs network delineation. The assessment was produced by running the beta version of the ocelote command line tool on the input datasets. 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 perimeter dem dnbr severity kf evt retainments 20240920 Jonathan M King USGS - ROCKY MOUNTAIN REGION Research Physical Scientist mailing and physical

Colorado School of Mines, 1711 Illinois St

Golden CO 80401 3032738500 jking@usgs.gov Vector String 457 0.0197754793 0.0235836429 Decimal seconds North_American_Datum_1983 GRS 1980 6378137.0 298.257222101 Shapefiles.zip Zip archive of hazard modeling results. Producer Defined Segment_ID Unique, ascending, non-sequential integer ID assigned to each stream segment. Producer Defined 1 Inf T Terrain variable for the M1 model. The proportion of catchment area that is both (1) burned at moderate-or-high severity, and (2) has a slope angle of at least 23 degrees. Producer Defined 0.0 1 F Fire variable for the M1 model. Mean catchment dNBR divided by 1000. Producer Defined -Inf Inf Unitless S Soil variable for the M1 model. Mean catchment KF-factor. Producer Defined 0 Inf inches per hour Bmh_km2 Catchment area burned at moderate or high severity. Producer Defined 0.0 Inf Square kilometers Relief Vertical relief Producer Defined 0 Inf Area_km2 Total catchment area Producer Defined 0 Inf Square kilometers BurnRatio The proportion of catchment that is burned. Producer Defined 0.0 1.0 DevArea Developed catchment area Producer Defined 0.0 1 Square kilometers ConfAngle Confinement angle Producer Defined 0 180 degrees Slope Slope Producer Defined 0 Inf Unitless (rise / run) InPerim Whether each stream segment intersects the fire perimeter Producer Defined 0 1 Boolean hil2024-field-descriptions.txt Descriptions of data fields in Shapefiles.zip. Producer Defined hil2024-median-thresholds.csv Table of median rainfall thresholds as calculated over the stream segments and catchment basins. Producer Defined hil2024-metadata.txt Auxiliary metadata about the fire event and implementation of the hazard assessment. Producer Defined U.S. Geological Survey - ScienceBase mailing address

Denver Federal Center

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Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P13GTMAX None 20251119 Jonathan M King USGS - ROCKY MOUNTAIN REGION Research Physical Scientist mailing and physical

Colorado School of Mines, 1711 Illinois St

Golden CO 80401 3032738500 jking@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998