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Apple Post-Fire BAER

Unit Information

San Bernardino National Forest
U.S. Forest Service
602 S. Tippecanoe Ave.
San Bernardino, CA 92408

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Incident Contact

BAER Information
Phone: 707-853-4243
Hours: 8am-8pm

Emergency Assessment of Post-Fire Debris Flow Hazards

Apple Post-Fire BAER Burned Area Emergency Response
News – 8/20/2020

 Emergency Assessment of Post-Fire Debris Flow Hazards

The Forest Service (USFS) Burned Area Emergency Response (BAER)assessment team coordinated early with US Geological Survey (USGS) staff during its evaluation of the Apple Fire burned area to strategically assess potential post-fire impacts to the watersheds and predicted debris flow response during damaging storm events.

From the USGS website found at https://landslides.usgs.gov/hazards/postfire_debrisflow/:

“Wildfire can significantly alter the hydrologic response of a watershed to the extent that even modest rainstorms can produce dangerous flash floods and debris flows. The USGS conducts post-fire debris-flow hazard assessments for select fires in the Western U.S.  We use geospatial data related to basin morphometry, burn severity, soil properties, and rainfall characteristics to estimate the probability and volume of debris flows that may occur in response to a design storm.”

USGS used the BAER team’s soil burn severity analysis of the area burned by the Apple Fire to estimate post-fire debris-flow hazards, including the likelihood of debris flow (in %), potential volume of debris flow, and combined relative debris flow hazard. These predictions are made at the scale of the drainage basin, and at the scale of the individual stream segment. The USGS Apple Post-Fire Debris Flow Hazard Assessment estimates convey these hazards for the Apple burn area.  The map on the USGS website shows the Estimates of probability, volume, and combined hazard are based upon a design storm with a peak 15-minute rainfall intensity of 24 millimeters per hour (1 inch/hour).   The online interactive map is posted at (click on the button at the top right corner of the map to show different predictions according to storm estimates): https://landslides.usgs.gov/hazards/postfire_debrisflow/detail.php?objectid=290.

USGS Fact Sheet 176-97, entitled “Debris Flow Hazards in the United States” contains information used to interpret the debris flow map and analysis that was incorporated into the BAER assessment team’s anticipated soil erosion and hydrologic response findings.  According to the USGS, “Analysis of data collected from studies of debris flows following wildfires can answer many of the questions fundamental to post-fire hazard assessments— what and why, where, when, how big, and how often?”  This information is extremely important in assisting the public in increasing their awareness of the areas where there may be a higher increase in flooding, sediment and soil erosion, and a high probability of debris flows –- all of which are potential risks to human life, safety, and property.

SPECIAL NOTE: Everyone near and downstream from the burned areas should remain alert and stay updated on weather conditions that may result in heavy rains over the burn scars. Flash flooding may occur quickly during heavy rain events-be prepared to take action. Current weather and emergency notifications can be found at the National Weather Service website: www.weather.gov/sgx/.

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