Soil Burn Severity Data Released
PORTLAND, OR, October 8, 2020 – Burned Area Emergency Response (BAER) specialists from the U.S. Forest Service have finalized the Soil Burn Severity map for the following fires: White River, Riverside, Beachie Creek, Lionshead, Holiday Farm, Archie Creek, and Thielsen. Soil burn severity is classified into 4 levels: unburned, low, moderate and high.
BAER soil scientists used the burn area reflectance classification satellite image product to prioritize places in the field to assess soil burn severity. These individuals sampled accessible sites to evaluate soil changes caused by the fire. In particular, they collected information on ground cover, ash color, soil depth and structure, intact roots, and water repellency in order to build a picture of soil burn severity.
The analysis showed the following distribution of severity by acres:
Lionshead (204,179 acres)
Unburned: 29,313 (14%) | Low: 78,679 (39%) | Moderate: 78,547 (38%) | High: 17,639 (9%)
Beachie Creek (192,631 acres)
Unburned: 8,462 (4%) | Low: 63,280 (33%) | Moderate: 100,920 (52%) | High: 19,968 (10%)
White River (17,774 acres)
Unburned: 2,687 (15%) | Low: 11,265 (63%) | Moderate: 3,391 (19%) | High: 430 (2%)
Riverside (137,792 acres)
Unburned: 18,192 (13%) | Low: 47,548 (35%) | Moderate: 55,118 (40%) | High: 16,934 (12%)
Holiday Farm (173,050 acres)
Unburned: 7,479 (4%) | Low: 42,233 (24%) | Moderate: 107,234 (62%) | High: 16,104 (9%)
Archie Creek (131,419 acres)
Unburned: 11,682 (9%) | Low: 18,666 (14%) | Moderate: 57,855 (44%) | High: 43,216 (33%)
Thielsen (9,921 acres)
Unburned: 914 (9%) | Low: 4,171 (42%) | Moderate: 4,295 (43%) | High: 542 (5%)
Still being analyzed
BAER post-fire assessment teams use the soil burn severity data to identify if there are areas of concern where increased soil erosion, accelerated surface water run-off, and debris flows have the potential to impact human life and safety, property, and critical natural and cultural resources from rain events. This information helps the BAER team determine areas where potential emergency stabilization treatments may occur.
The Soil Burn Severity map isn’t an erosion risk map but does help define areas where potential increases in the rates of erosion and run-off are expected from steep hillslopes with high and moderate soil burn severity. Areas located downstream from moderate and high soil burn severity may experience increased rates of erosion, debris flows, and surface run-off due to cumulative effects.