Single Publication

Middle Fork Complex (Nellie-Bulldog-Flat Fires) 

Post-Fire BAER Soil Burn Severity Map Released

October 14, 2024

USDA Forest Service Burned Area Emergency Response (BAER) specialists recently completed their data gathering and analysis for the Middle Fork Complex wildfire burned areas to produce a post-fire Soil Burn Severity (SBS) map. 

The BAER assessment team used initial remote sensing imagery with their field-validated soils data, to develop and produce a map showing soil burn severity levels for the burned area. The SBS is broken into four different classes: unburned/very low (green), low (blue), moderate (yellow), and high (red). For more information on these different SBS classifications, see the BAER Information Brief at: Idbof Boise Nf Postfire Baer 2024 - | InciWeb (wildfire.gov).

The BAER SBS map and data display categories of unburned/very low, low, moderate, and high soil burn severity in different colors for the different categories along with a table displaying these GIS data totals:

• For the Nellie Fire, approximately 66% of the 50,158 acres analyzed by the BAER team are either unburned/very low or low soil burn severity, while 30% sustained a moderate soil burn severity, and about 4% were identified as having high soil burn severity.
• For the Bulldog Fire, approximately 74% of the 11,420 acres analyzed by the BAER team are either unburned/very low or low soil burn severity, while 25% sustained a moderate soil burn severity, and about 1% were identified as having high soil burn severity.
• For the Flat Fire, approximately 67% of the 3,762 acres analyzed by the BAER team are either unburned/very low or low soil burn severity, while 22% sustained a moderate soil burn severity, and about 11% were identified as having high soil burn severity.

There are several types of fire severity and intensity maps that you may see. Although the maps look different for the same fire, they are accurate. This is because fire severity or intensity are different metrics of the fire effects on a specific resource such as soils, tree canopies, vegetation or wildlife habitat. Burned Area Emergency Response (BAER) maps are primarily measures of fire effects on soils. See also Fire Intensity vs. Soil Severity Effects BAER Information Brief at: Idbof Boise Nf Postfire Baer 2024 - | InciWeb (wildfire.gov).

The BAER team relies on their final soil burn severity map to produce data, which they are using in their subsequent modeling and determination of post-fire runoff, erosion, and sedimentation. The BAER team, and the US Geological Survey (USGS) utilize the soil burn severity map as an analysis tool to estimate post-fire watershed response to precipitation events. In specific areas that experienced moderate to high burn severity, there could be increased runoff from steep hillslopes which could result in increases of post-fire soil erosion, sedimentation, and potential debris flows.

The Middle Fork Complex (Nellie-Bulldog-Flat) SBS map can be downloaded at the Boise NF Post-Fire BAER 2024 InciWeb site: Idbof Boise Nf Postfire Baer 2024 Information | InciWeb (wildfire.gov) under the “Maps” tab.

BAER SAFETY MESSAGE: Everyone near and downstream from the burned areas should remain alert and stay updated on weather conditions that may result in heavy rains and increased water runoff. Flash flooding may occur quickly during heavy rain events--be prepared to act. Current weather and emergency notifications can be found at the National Weather Service website: www.weather.gov/boi/.

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