Open-File Report 2011–1251
This report presents an emergency assessment of potential debris-flow hazards from basins burned by the 2011 Motor fire in the Sierra and Stanislaus National Forests, Calif. Statistical-empirical models are used to estimate the probability and volume of debris flows that may be produced from burned drainage basins as a function of different measures of basin burned extent, gradient, and soil physical properties, and in response to a 30-minute-duration, 10-year-recurrence rainstorm. Debris-flow probability and volume estimates are then combined to form a relative hazard ranking for each basin. This assessment provides critical information for issuing warnings, locating and designing mitigation measures, and planning evacuation timing and routes within the first two years following the fire.
First posted September 30, 2011
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Cannon, S.H., and Michael, J.A., 2011, Emergency assessment of postwildfire debris-flow hazards for the 2011 Motor Fire, Sierra and Stanislaus National Forests, California: U.S. Geological Survey Open-File Report 2011–1251, 10 p.
Methods and Approach
Debris-Flow Probability Estimates
Debris-Flow Volume Estimates
Combined Relative Debris-Flow Hazard Rankings
Limitations of Assessment
Summary and Conclusions