Wildland fires are inevitable in the western United States. Expansion of man-made
developments into fire-prone wildlands has created situations where wildfires
can destroy lives and property, as can the flooding and debris flows
that are common in the aftermath of the fires. Fast-moving, highly destructive
debris flows triggered by intense rainfall are one of the most dangerous
post-fire hazards. Such debris flows are particularly dangerous because
they tend to occur with little warning. Their mass and speed make them
particularly destructive: debris flows can strip vegetation, block drainages,
damage structures, and endanger human life.
The U.S. Geological Survey’s Landslide Hazards Program is participating in a
multi-agency cooperative effort to investigate debris flows in burned
areas of southern California and other parts of the western United States.
Participating agencies are the USDA Forest Service, the Natural Resources
Conservation Service, and the California, Colorado, and Montana Geological
Surveys. The objective of this project is to develop methods needed to
estimate the locations, probability of occurrence, and size of potentially
destructive debris flows. Public officials can use this information to
plan and execute emergency response and post-fire rehabilitation.
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?