Wildfire can radically change a mountainous landscape such that even a modest rainstorm is capable of producing deadly and destructive flash flooding and debris flows.
Recent Conditions
Instrumentation was installed in the autumn following the 2021 Dixie Fire and are used to monitor and detect changes in local hillslope hydrologic conditions. Soil-water content, soil suction, and groundwater pressure are measured in two sensor nests on the same hillslope. Data for the site include:
- Rainfall
- Air temperature & Battery Voltage
- Upper nest: soil-water content, soil suction, and groundwater pressure
- Lower nest: soil-water content, soil suction, and groundwater pressure
Data are recorded every minute and updated on the graph every 60 minutes.
Project Background
The 2021 Dixie Fire burned nearly one million acres in northern California, including large portions of the Feather River Canyon. An emergency assessment of post-fire debris-flow hazards (USGS, 2021) indicated that numerous drainages across the extensive burn area have a high susceptibility to debris flows. Evidence of past landslide activity in the region following the 2012 Chips Fire (which was reburned by the 2021 Dixie Fire) suggests debris flows were triggered by both distributed runoff and erosion and shallow landslides. Preliminary analysis of initiation sites also suggests the locations of mass movement were correlated with bedrock lithology. In the autumn following the 2021 Dixie Fire, the USGS Landslide Hazards Program installed two hillslope hydrologic monitoring stations in contrasting soil types to investigate if one soil type is more susceptible to post-fire mass movement than the other. These data will inform how soils information could be incorporated into future hazard models and will also be used to test a new physically based modeling framework for the change in rainfall thresholds with time following wildfire and with style of initiation (Thomas et al., 2021).
Emergency Assessment of Post-Fire Debris-Flow Hazards
- Overview
Wildfire can radically change a mountainous landscape such that even a modest rainstorm is capable of producing deadly and destructive flash flooding and debris flows.
Recent Conditions
Instrumentation was installed in the autumn following the 2021 Dixie Fire and are used to monitor and detect changes in local hillslope hydrologic conditions. Soil-water content, soil suction, and groundwater pressure are measured in two sensor nests on the same hillslope. Data for the site include:
- Rainfall
- Air temperature & Battery Voltage
- Upper nest: soil-water content, soil suction, and groundwater pressure
- Lower nest: soil-water content, soil suction, and groundwater pressure
Data are recorded every minute and updated on the graph every 60 minutes.
Project Background
The 2021 Dixie Fire burned nearly one million acres in northern California, including large portions of the Feather River Canyon. An emergency assessment of post-fire debris-flow hazards (USGS, 2021) indicated that numerous drainages across the extensive burn area have a high susceptibility to debris flows. Evidence of past landslide activity in the region following the 2012 Chips Fire (which was reburned by the 2021 Dixie Fire) suggests debris flows were triggered by both distributed runoff and erosion and shallow landslides. Preliminary analysis of initiation sites also suggests the locations of mass movement were correlated with bedrock lithology. In the autumn following the 2021 Dixie Fire, the USGS Landslide Hazards Program installed two hillslope hydrologic monitoring stations in contrasting soil types to investigate if one soil type is more susceptible to post-fire mass movement than the other. These data will inform how soils information could be incorporated into future hazard models and will also be used to test a new physically based modeling framework for the change in rainfall thresholds with time following wildfire and with style of initiation (Thomas et al., 2021).
Sources/Usage: Public Domain.The USGS “Chambers” site is located in the Plumas National Forest in northern California. The site consists of instrumentation monitoring the hillslope in the lower part of the image. The hillslope exhibits moderate soil burn severity and hosts sandy soils derived from granitic bedrock. - Science
Emergency Assessment of Post-Fire Debris-Flow Hazards
Estimates of the probability and volume of debris flows that may be produced by a storm in a recently burned area, using a model with characteristics related to basin shape, burn severity, soil properties, and rainfall. 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... - Publications