Overview of Hazards and Risk Assessments Active
Landslide hazard and risk assessments help people understand the dangers from landslides to their towns and cities, homes, facilities, and businesses. Landslide hazard assessments are estimates of the probability that landslides will affect a particular area or location, typically within a given timeframe.
Wildfire can have extreme effects on the hydrologic response of a watershed, and debris-flow activity is among the most destructive consequences of these effects. Recent fires in the western U.S. have impacted hundreds of thousands of acres of steep terrain (much of which is public land), making it susceptible to increased erosion and debris-flow activity. The continued high likelihood of catastrophic wildfires in the western U.S. and the encroachment of development into fire-prone areas have created the need to develop tools and methods to identify and quantify the potential hazards posed by debris flows generated from burned watersheds. Science-based information on post wildfire debris-flow hazards is critically needed by Federal, State, and local agencies to mitigate the impacts of fire on people, their property, and natural resources.
This project focuses on developing rapid and accurate methods to assess post-fire debris-flow hazards and the applied research needed and better understanding the processes that control post-fire debris-flow initiation and growth. We are accomplishing these tasks through a combination of field work, mapping, debris-flow monitoring, laboratory testing, numerical modeling, and statistical and theoretical analyses to reach project goals.
Application of predictive models before a wildfire can also help with pre-fire planning. In pre-fire applications, the models can identify sensitive drainage basins and thus guide forest restoration and fire protection efforts. We are collaborating with the National Weather Service (NWS) for the operation and advancement of the joint NWS/USGS flash flood and debris-flow early warning system for recently burned basins in southern California. As part of the warning system protocol, the USGS has agreed to provide rainfall intensity-duration thresholds that define the rainfall conditions that are likely to result in flash floods and debris flows, as well as make post-fire debris-flow hazard maps for major fires in southern California. Post-fire debris-flow hazard assessments are now conducted across the western U.S., and we are working with NWS to expand warning capabilities beyond southern CA.
We seek to better understand the processes that control post-fire debris-flow initiation and growth, including post-fire infiltration, runoff, sediment transport, erosion, and deposition. During fieldwork, we make direct measurements of natural debris flows and associated processes and a modeling component that develops physically based models that explain the observations. These components identify the hydrologic, topographic, and geologic controls on the timing, location, and magnitude of post-fire debris flows. This knowledge will be incorporated into the predictive methods and helps advance the NWS/USGS warning system.
- Overview
Landslide hazard and risk assessments help people understand the dangers from landslides to their towns and cities, homes, facilities, and businesses. Landslide hazard assessments are estimates of the probability that landslides will affect a particular area or location, typically within a given timeframe.
Sources/Usage: Public Domain. View Media DetailsUSGS geologists deployed to Santa Barbara County to support a geohazard assessment of the Montecito area Wildfire can have extreme effects on the hydrologic response of a watershed, and debris-flow activity is among the most destructive consequences of these effects. Recent fires in the western U.S. have impacted hundreds of thousands of acres of steep terrain (much of which is public land), making it susceptible to increased erosion and debris-flow activity. The continued high likelihood of catastrophic wildfires in the western U.S. and the encroachment of development into fire-prone areas have created the need to develop tools and methods to identify and quantify the potential hazards posed by debris flows generated from burned watersheds. Science-based information on post wildfire debris-flow hazards is critically needed by Federal, State, and local agencies to mitigate the impacts of fire on people, their property, and natural resources.
This project focuses on developing rapid and accurate methods to assess post-fire debris-flow hazards and the applied research needed and better understanding the processes that control post-fire debris-flow initiation and growth. We are accomplishing these tasks through a combination of field work, mapping, debris-flow monitoring, laboratory testing, numerical modeling, and statistical and theoretical analyses to reach project goals.
Application of predictive models before a wildfire can also help with pre-fire planning. In pre-fire applications, the models can identify sensitive drainage basins and thus guide forest restoration and fire protection efforts. We are collaborating with the National Weather Service (NWS) for the operation and advancement of the joint NWS/USGS flash flood and debris-flow early warning system for recently burned basins in southern California. As part of the warning system protocol, the USGS has agreed to provide rainfall intensity-duration thresholds that define the rainfall conditions that are likely to result in flash floods and debris flows, as well as make post-fire debris-flow hazard maps for major fires in southern California. Post-fire debris-flow hazard assessments are now conducted across the western U.S., and we are working with NWS to expand warning capabilities beyond southern CA.
We seek to better understand the processes that control post-fire debris-flow initiation and growth, including post-fire infiltration, runoff, sediment transport, erosion, and deposition. During fieldwork, we make direct measurements of natural debris flows and associated processes and a modeling component that develops physically based models that explain the observations. These components identify the hydrologic, topographic, and geologic controls on the timing, location, and magnitude of post-fire debris flows. This knowledge will be incorporated into the predictive methods and helps advance the NWS/USGS warning system.