“How long, after wildfire do I need to be concerned about debris flows in my area?”
The USGS conducts research to evaluate the recovery of burned areas using field monitoring stations, satellite-based data, and numerical models. This work facilitates the development of USGS hazard assessment products that are geared to answer this question.
Timelapse photography of vegetation recovery following the 2020 CZU Lightning Complex in the Santa Cruz Mountains of northern California. Each two-year image sequence begins four and a half months after the wildfire was contained. Time between photographs is approximately two weeks.
Chaparral vegetation community, which experienced moderate to severe soil burn severity.
Redwood vegetation community, which experienced low to moderate soil burn severity.
Important Publications
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Characterizing changes in postfire debris-flow hazard as burned areas recover Characterizing changes in postfire debris-flow hazard as burned areas recover
Emergency assessments of postfire debris-flow hazards that are performed by the U.S. Geological Survey (USGS) provide estimates of debris-flow likelihood and rainfall triggering conditions that are used for evaluating and managing runoff-generated debris-flow hazards in recently burned areas throughout the western United States. Although the immediate postfire period, within roughly one...Landsliding follows signatures of wildfire history and vegetative regrowth in a steep coastal shrubland Landsliding follows signatures of wildfire history and vegetative regrowth in a steep coastal shrubland
Five years after the deadly and destructive 9 January 2018 Montecito debris flows (Santa Barbara County, California, USA), an atmospheric river storm on 9 January 2023 triggered widespread landsliding that affected many of the same drainages in the Santa Ynez Mountains. Using high-resolution aerial imagery, we identified >10,000 landslides over an ∼160 km2 area. Most of the landslides...How long do runoff-generated debris-flow hazards persist after wildfire? How long do runoff-generated debris-flow hazards persist after wildfire?
Runoff-generated debris flows are a potentially destructive and deadly response to wildfire until sufficient vegetation and soil-hydraulic recovery have reduced susceptibility to the hazard. Elevated debris-flow susceptibility may persist for several years, but the controls on the timespan of the susceptible period are poorly understood. To evaluate the connection between vegetation...Postwildfire soil‐hydraulic recovery and the persistence of debris flow hazards Postwildfire soil‐hydraulic recovery and the persistence of debris flow hazards
Deadly and destructive debris flows often follow wildfire, but understanding of changes in the hazard potential with time since fire is poor. We develop a simulation‐based framework to quantify changes in the hydrologic triggering conditions for debris flows as postwildfire infiltration properties evolve through time. Our approach produces time‐varying rainfall intensity‐duration...
Watch to learn more
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Updating methods for postfire debris-flow hazard assessment
For more than a decade, the U.S. Geological Survey (USGS) has provided stakeholders and land managers with postfire debris-flow hazard information to assist them in considering important questions about postfire debris flows, such as “Where will they happen?”, “When will they happen?”, or “How big will they be?” Alongside assessing postfire debris-flow hazards for hundreds of burned areas to date...
-
“How long, after wildfire do I need to be concerned about debris flows in my area?”
The USGS conducts research to evaluate the recovery of burned areas using field monitoring stations, satellite-based data, and numerical models. This work facilitates the development of USGS hazard assessment products that are geared to answer this question.
Timelapse photography of vegetation recovery following the 2020 CZU Lightning Complex in the Santa Cruz Mountains of northern California. Each two-year image sequence begins four and a half months after the wildfire was contained. Time between photographs is approximately two weeks.
Chaparral vegetation community, which experienced moderate to severe soil burn severity.
Redwood vegetation community, which experienced low to moderate soil burn severity.
Important Publications
-
Characterizing changes in postfire debris-flow hazard as burned areas recover Characterizing changes in postfire debris-flow hazard as burned areas recover
Emergency assessments of postfire debris-flow hazards that are performed by the U.S. Geological Survey (USGS) provide estimates of debris-flow likelihood and rainfall triggering conditions that are used for evaluating and managing runoff-generated debris-flow hazards in recently burned areas throughout the western United States. Although the immediate postfire period, within roughly one...Landsliding follows signatures of wildfire history and vegetative regrowth in a steep coastal shrubland Landsliding follows signatures of wildfire history and vegetative regrowth in a steep coastal shrubland
Five years after the deadly and destructive 9 January 2018 Montecito debris flows (Santa Barbara County, California, USA), an atmospheric river storm on 9 January 2023 triggered widespread landsliding that affected many of the same drainages in the Santa Ynez Mountains. Using high-resolution aerial imagery, we identified >10,000 landslides over an ∼160 km2 area. Most of the landslides...How long do runoff-generated debris-flow hazards persist after wildfire? How long do runoff-generated debris-flow hazards persist after wildfire?
Runoff-generated debris flows are a potentially destructive and deadly response to wildfire until sufficient vegetation and soil-hydraulic recovery have reduced susceptibility to the hazard. Elevated debris-flow susceptibility may persist for several years, but the controls on the timespan of the susceptible period are poorly understood. To evaluate the connection between vegetation...Postwildfire soil‐hydraulic recovery and the persistence of debris flow hazards Postwildfire soil‐hydraulic recovery and the persistence of debris flow hazards
Deadly and destructive debris flows often follow wildfire, but understanding of changes in the hazard potential with time since fire is poor. We develop a simulation‐based framework to quantify changes in the hydrologic triggering conditions for debris flows as postwildfire infiltration properties evolve through time. Our approach produces time‐varying rainfall intensity‐duration...
Watch to learn more
-
-
Updating methods for postfire debris-flow hazard assessment
For more than a decade, the U.S. Geological Survey (USGS) has provided stakeholders and land managers with postfire debris-flow hazard information to assist them in considering important questions about postfire debris flows, such as “Where will they happen?”, “When will they happen?”, or “How big will they be?” Alongside assessing postfire debris-flow hazards for hundreds of burned areas to date...
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