T234 Engineering Geology for the Betterment of Society: Honoring the Legacy of Jerome V. De Graff

Wednesday, 13 October 2021
1:30 PM - 5:30 PM
Portland Ballroom 254 (Hybrid Room)

SIXTY YEARS OF POST-FIRE ASSESSMENT AND MONITORING ON NON-FEDERAL LANDS IN CALIFORNIA: WHAT HAVE WE LEARNED?

Paper number: T234-4
Program: Technical Sessions
Time: 2:05 PM – 2:20 PM

Authors

Abstract

California has a long history of damage from post-fire flooding and debris flows, often described as the fire-flood sequence. Post wildfire assessment has been conducted on California’s non-federal lands for more than 60 years. From 1956 to 1999, the focus was on aerial grass seeding for emergency revegetation. Later, hillslope treatments including straw mulch and hydromulch were shown to be more effective in reducing erosion, but their high cost make them generally infeasible. In the 1990’s the state moved away from aerial grass seeding and embraced a dual strategy for minimizing post-fire impacts. First, fire suppression repair work became consistently applied to all fires. Typical repairs include installing waterbreaks on firelines, grading roads, removing soil from crossings, and mulching mechanically disturbed areas near streams. Second, there was greater use of interdisciplinary teams to evaluate life-safety and property threats from debris flows, flooding, and rockfall on non-federal lands. The state process was pioneered by the California Geological Survey (CGS) in 1993 and has benefited from advances in spatially-explicit modeling since 2000. Currently, state teams are co-led by the California Department of Forestry and Fire Protection (CAL FIRE) and CGS, with evaluations only conducted on fires with significant threats. This approach has been found to be effective for rapidly notifying emergency management agencies of hazards, helping to protect lives and property. This process will benefit from further technological advances, monitoring, and improved modeling. Strategies for improving post-fire hazard evaluation and better emergency preparedness through pre-fire hazard mitigation planning are provided.

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-365999

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