Wragg Fire 4-Class Burn Severity Categorization

Identification_Information:
Citation:
Citation_Information:
Originator: USGS EROS
Publication_Date: 8/13/2015
Title: Wragg fire, located about 4 miles west of Winters, CA.

Geospatial_Data_Presentation_Form: raster digital data
Publication_Information:
Publication_Place: Sioux Falls, South Dakota USA
Publisher: U.S. Geological Survey
Online_Linkage: http://edc.usgs.gov
Description:
Abstract:The pre-fire and post-fire subsets included were used to create a differenced Normalized Burn Ratio (dNBR) image. The dNBR image attempts to portray the variation of burn severity within a fire. The severity ratings are influenced by the effects to the canopy.The severity rating is based upon a composite of the severity to the understory (grass, shrub layers), midstory trees and overstory trees. Because there is often a strong correlation between canopy consumption and soil effects, this algorithm works in many cases for BAER teams whose objective is a soil burn severity assessment.It is not, however, accurate in all ecosystems or fires.

Purpose: These data were created by USGS EROS to support Burned Area Emergency Response (BAER) teams.
Supplemental_Information:
Fire Name: Wragg
Agency: BLM
Land Management Unit: CA Arcata FO
Type of assessment: Immediate Response (BARC)
Fire size (acres) as listed on the Situation Report: 8,051
Pre-Fire Landsat Path/Row and Date: Landsat 8 044/033, 8/09/2014
Post-Fire Landsat Path/Row and Date: Landsat 8 044/033, 8/12/2015
Output Dataset Projection: UTM
UTM Zone: 10
Spheroid Name: WGS84
Datum: WGS84

Product List:

wragg_pre754_20140809_l8.img = Pre-Fire Landsat scene.

wragg_post754_20150812_l8.img = Post-Fire Landsat scene.


wragg_barc256_20150812-20140809_clip.img = 256-class (0-255) continuous image representing fire severity. This dataset is meant to be adjusted if thevBARC4 does not provide a good estimate of fire severity. It is anticipated that users will adjust the breakpoints between classes, then recode to their desired 3 or 4 classes.

wragg_dnbr1000_20150812-20140809.img = full precision dNBR image in ERDAS Imagine format.

wragg_barc4_20150812-20140809_clip.img = Four category severity classification subset in ERDAS Imagine format with values:
0 = background/fill
1 = unchanged / very low (Dark Green)
2 = low severity (Cyan)
3 = moderate severity (Yellow)
4 = high severity (Red)
5 = enhanced greenness
6 = No Data (clouds, shadow, data gaps, etc.)




Time_Period_of_Content:
Time_Period_Information:
Multiple_Dates/Times:
Single_Date/Time:
Calendar_Date:
Single_Date/Time:
Calendar_Date:
Currentness_Reference: ground condition
Status:
Progress: Evaluation of methods in process
Maintenance_and_Update_Frequency: As needed
Keywords:
Theme:
Theme_Keyword_Thesaurus: none
Theme_Keyword: Wildland Fire
Theme_Keyword: Normalized Burn Ratio (NBR)
Theme_Keyword: Fire Severity
Theme_Keyword: USGS EROS
Theme_Keyword: Landsat
Place:
Place_Keyword_Thesaurus: none
Place_Keyword: Winters
Place_Keyword: CA
Access_Constraints: FTP data sets are available to any user.
Use_Constraints: There are no restrictions on use, except for reasonable and proper acknowledgement of information sources.
Data_Set_Credit: USGS EROS
Native_Data_Set_Environment: ERDAS Imagine, ARCInfo
Data_Quality_Information:
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report: These data were terrain corrected using a USGS digital elevation model with less than 1/2 pixel RMS error.
Lineage:
Process_Step:
Process_Description:
These data products are derived from Landsat 8 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 Landsat images are terrain corrected and corrected to Top of Atmosphere reflectance. The Normalized Burn Ratio (NBR) is computed for each date of imagery (Landsat 8 bands) using the following formula:
(Band 5(NIR) - Band 7(SWIR) / (Band 5 + Band 7) = 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 products are a generalization of the raw dNBR dataset. Both BARC products have been resampled to unsigned 8-bit images and are easily viewed and adjusted within ArcGIS.

The classes represented on the BARC products are created with thresholds chosen by an analyst at USGS EROS.These thresholds can be roughly related back to original dNBR values by multiplying by 5 and then subtracting 275 (for example, a BARC256 value of 100 would relate to a dNBR value of 225).The thresholds used on this particular fire are:

Unchanged: All values 0 - 85
Low:All values86 - 119
Moderate: All values 120 - 197
High:All values 198 - 255
No Data/Clouds: All values



General descriptions of the severity classes are below:

Unchanged: This means the area after the fire was indistinguishable from pre-fire conditions.
This does not always indicate the area did not burn.
Low: This severity class represents areas of surface fire with little change in cover and little
mortality of the dominant vegetation.
Moderate:This severity class is between low and high and means there is a mixture of effects on the
dominant vegetation.
High: This severity class represents areas where the canopy has high to complete consumption.

Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Vertical_Count: 1
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name:
Universal_Transverse_Mercator:
UTM_Zone_Number:
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: row and column
Coordinate_Representation:
Abscissa_Resolution:
Ordinate_Resolution:
Planar_Distance_Units: meters
Geodetic_Model:
Horizontal_Datum_Name:
Ellipsoid_Name:
Semi-major_Axis:
Denominator_of_Flattening_Ratio:
Distribution_Information:
Resource_Description: Downloadable Data
Metadata_Reference_Information:
Metadata_Date: 8/13/2015
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: USGS EROS
Contact_Person: Randy McKinley
Contact_Address:
Address_Type: 47914 252nd St
City: Sioux Falls
State_or_Province: SD
Postal_Code: 57198
Contact_Voice_Telephone: 605-594-2745