Identification Information Citation Originator: USDA Forest Service, Geospatial Technology and Applications Center, BAER Imagery Support Program Publication Date: 2024-10-20 Title: Soil Burn Severity Dataset for the chimney Fire occurring on the Sawtooth National Forest Publication Information Publication Place: Salt Lake City, Utah, USA Publisher: USDA Forest Service Geospatial Data Presentation Form: raster digital data Online Linkage: https://fsapps.nwcg.gov/afm/baer/download.php Description Abstract: This soil burn severity dataset was derived from Landsat 9 data and field validated by a Forest Service Burned Area Emergency Response (BAER) team. It is based upon an initial Burned Area Reflectance Classification (BARC) dataset created by analyzing satellite imagery. A pre-fire and post-fire Landsat 9 scene were processed to develop a differenced Normalized Burn Ratio (dNBR) image. The dNBR image attempts to portray the variation of burn severity within a fire and captures the combined effects of the fire to vegetation and soil components of the ecosytem. The preliminary BARC dataset was assessed by a Forest Service BAER team and modified, if necessary, based on field conditions. Purpose: These data were created by the USDA Forest Service Geospatial Technology and Applications Center (GTAC) to support Burned Area Emergency Response (BAER) teams. Supplemental Information Fire Name: chimney Agency: USDA Forest Service Type of assessment: Emergency Fire size (as mapped): 6771 acres Pre-Fire Imagery Date : 2024-09-01 Post-Fire Imagery Date : 2024-09-24 Output Dataset Projection: NAD_1983_UTM_Zone_11N Datum: D_North_American_1983 Spheroid Name: GRS_1980 Mapping Comments: None Product List chimney_id4345411505720240902_sbs.tif = Soil burn severity (SBS) dataset in raster format chimney_id4345411505720240902_SBS.png = PNG thumbnail version of the SBS Time Period of Content Multiple Dates/Times Single Date/Time Calendar Date: 2024-09-01 (pre-fire image) Single Date/Time Calendar Date: 2024-09-24 (post-fire image) Currentness Reference: Severity data correspond to the date of the post-fire image. Status Progress: Evaluation of methods in process Maintenance and Update Frequency: As needed Spatial Domain Bounding Coordinates West Bounding Coordinate: 649930.5802766086 East Bounding Coordinate: 664780.5802766086 North Bounding Coordinate: 4825424.054964101 South Bounding Coordinate: 4808054.054964101 Keywords Theme Theme Keyword Thesaurus: none Theme Keyword: Wildland Fire Theme Keyword: Wildfire Theme Keyword: Burned Area Emergency Response Theme Keyword: BAER Theme Keyword: dNBR Theme Keyword: Fire Severity Theme Keyword: Burn Severity Theme Keyword: USDA Forest Service Place Place Keyword Thesaurus: none Place Keyword: ID Place Keyword: chimney Fire Access Constraints: These data are publicly available. Use Constraints: There are no restrictions on use, except for reasonable and proper acknowledgement of information sources and limitations as preliminary/draft data. Data Set Credit: USDA Forest Service Native Data Set Environment: GeoTiff Data Quality Information Positional Accuracy Horizontal Positional Accuracy Horizontal Positional Accuracy Report: Landsat data are terrain corrected using ground control points and processed to an RMSE of less than 1/2 pixel. Lineage Process Step Process Description: These data products are derived from Landsat 9 data. Pre-fire and post-fire scenes are analyzed to create a differenced Normalized Burn Ratio (dNBR) image. The dNBR image portrays the variation of burn severity within the fire. The pre- and post-fire images are terrain corrected and further processed to convert top of atmosphere reflectance. The Normalized Burn Ratio (NBR) is computed for the pre- and post-fire images using the following formula: (NIR Band - SWIR Band) / (NIR Band + SWIR Band) = NBR The Differenced NBR is computed to determine severity by subtracting the post-fire NBR from the pre-fire NBR: (PreNBR - PostNBR) = dNBR The BARC image was reclassified using data from aerial reconnaissance due to lack of groundbased access into the perimeter of the burned area. A soil scientist, hydrologist, and botanist flew over the burned area with the BARC imagery, took georeferenced photos in multiple locations with various burn severity throughout the fire, and discussed areas where the BARC should be adjusted. Photos and notes were used to reclassify the BARC to more accurately represent what was seen on the ground. Many areas mapped as high and moderate were scaled back due to the presence of remaining ground cover and the lack of burn severity in vegetation communities. The southern area initially had high amounts of moderate mapped, but it was found that most of this area had low soil burn severity. Soil burn severity classes were scaled back more in the south than they were in the north to reflect this difference. We talked about soil burn severity values this morning and we’d like to split the burned area into two sections to for reclassification. The area in BLM (south) had different vegetation (more sagebrush/shrubs/grasses) and is likely the reason why the reflectance classifications were overestimated more in the south than the north Original BARC thresholds: Unburned/Low threshold = 68 Low/Moderate threshold = 108 Moderate/High threshold = 186 Revised SBS thresholds (North side): Unburned/Low threshold = 68 Low/Moderate threshold = 150 Moderate/High threshold = 210 Revised SBS thresholds (South side): Unburned/Low threshold = 68 Low/Moderate threshold = 190 Moderate/High threshold = 235 General descriptions of the severity classes are below: Unburned / Very low: The area after the fire was indistinguishable from pre-fire conditions. This does not always indicate the area did not burn (i.e. canopy may be occluding the burn signal). Low: Areas of surface fire with little detected change in cover and little detected mortality of the dominant vegetation. Little to no change in the soil color, structure and condition occured. Moderate: This severity class is between low and high and means there is a mixture of detected effects on the dominant vegetation. High: Areas where the canopy has high to complete consumption. Changes to soil structure, color and condition are significant and hydrophobicity may have occured. Spatial Data Organization Information Direct Spatial Reference Method: Raster Raster Object Information Vertical Count: 1 Spatial Reference Information Horizontal Coordinate System Definition Planar Map Projection Map Projection Name: NAD_1983_UTM_Zone_11N Map Projection Parameters Standard Parallel: 0.0 Standard Parallel: 0.0 Longitude of Central Meridian: -117.0 Latitude of Projection Origin: 1.0]];-5120900 -9998100 450445547.391054;-100000 10000;-100000 10000;0.001;0.001;0.001;IsHighPrecisio False Easting: 500000.0 False Northing: 0.0 Planar Coordinate Information Planar Coordinate Encoding Method: row and column Coordinate Representation Abscissa Resolution: 30.0 Ordinate Resolution: 30.0 Planar Distance Units: Meter Geodetic Model Horizontal Datum Name: D_North_American_1983 Ellipsoid Name: GRS_1980 Semi-major Axis: 6378137.0 Denominator of Flattening Ratio: 298.257222101 Distribution Information Resource Description: Downloadable Data Metadata Reference Information Metadata Date: 2024-10-20 Metadata Contact Contact Information Contact Organization Primary Contact Organization: USDA Forest Service, Geospatial Technology and Applications Center (GTAC) Contact Person: Mark Nigrelli Contact Address Address Type: mailing address Address: 125 S. Sate St., Suite 7105 City: Salt Lake City State or Province: UT Postal Code: 84138 Contact Voice Telephone: 801 975 3479 Contact Electronic Mail Address: baerimagery@fs.fed.us