Shasta-Trinity National Forest
U.S. Forest Service
3644 Avtech Parkway
Redding, CA 96002
BAER specialists recently completed their data gathering and verification field work in the Fork Complex burn areas and finalized a Soil Burn Severity map. Soil Burn Severity grid mapping codes are 1=Unburned/Very Low, 2=Low, 3=Moderate, and 4=High.
The map shows that approximately 37% of the 36,500 acres analyzed by the BAER team within the fire perimeters of the Fork Complex are either unburned or have a low soil burn severity, while 62% sustained a moderate soil burn severity and 1% received a high soil burn severity.
The BAER assessment team used the map to model potential impacts to human life, safety, and property from storm events and considered emergency stabilization options for those critical resources.
BAER specialists concluded for the Fork Complex fires that the amount of high soil severity burn is low given time of year and comparison to other fires and is due to a heavy smoke inversion that set in and lack of wind driven events. This situation cooled the fire and moderated fire behavior to create slow moving ground fires with occasional torching and crown fires in the afternoon when the inversion would lift at higher elevations. The exception was the first two days when the fires grew rapidly due to winds, crowning, and lack of inversion. These conditions caused the moderate and low soil burn severity observed in this map.
BAER Soils Scientist Brad Rust stated, "Significant increases in the rates of erosion and run-off are expected from steep hillslopes with high and moderate soil burn severity. Erosion and run-off from unburned and low areas will not be significantly greater as a result of the fires."
The soil burn severity BAER map can be downloaded at the “2015 Shasta-Trinity Post-Fire BAER” InciWeb site as a JPEG or PDF version under the “maps” tab.
A "Field Guide for Mapping Post-Fire Soil Burn Severity" can help with interpreting the map and can be found online at http://www.fs.fed.us/rm/pubs/rmrs_gtr243.pdf.
SPECIAL NOTE: Everyone near and downstream from the Fork Complex fire areas should remain alert and stay updated on weather conditions that may result in heavy rains over the burn scar. Flash flooding may occur quickly during heavy rain events. Current weather and emergency notifications can be found at the National Weather Service, Eureka Office (http://www.wrh.noaa.gov/eka/) website.
Shasta-Trinity NF Post-Fire BAER Assessment information is available at http://inciweb.nwcg.gov/incident/4601/.