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#           The recurrence interval of post-fire debris-flow generating rainfall in the southwestern United States      

      August 21, 2020    

In the southwestern United States, post-fire debris flows commonly initiate during short bursts of intense rainfall. To date, the frequency of the rainfall rates has not been quantified. Here, we combine an existing database of debris-flow occurrences and corresponding peak storm intensities with a geospatial library of rainfall recurrence interval (RI) information and climate type to determine the distribution of the estimated frequencies of the rainfall associated with 316 observed post-fire debris flows in the southwestern United States. Our results indicate that a majority (77%) of the observed debris flows were triggered by rainfall intensities with RI less than 2 years. Climatic and geographic differences in RI were evident in our analysis. Debris flows in most of the analyzed climates within California, Colorado, and New Mexico were primarily associated with 1-year or less RI intensities, whereas debris flows in arid portions of Arizona, Colorado, and Utah tended to be generated during storms greater than 2-year RI. Event consequence, as defined by the impact on downstream communities and infrastructure, was not directly related to RI, as very destructive debris flows were initiated at a wide range of RI intensities. Our results highlight that post-fire debris-flow initiation can be expected during common rainstorms in the southwestern United States, therefore emergency management plans and risk mitigation efforts must focus on both extreme and frequent rainstorms.

## Citation Information

## Related Content

                  -              Data           
                  -              Connect           

September 29, 2020

####                 Data supporting an analysis of the recurrence interval of post-fire debris-flow generating rainfall in the southwestern United States              

Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

#### Dennis Michael Staley

##### Geomorphologist, Physical Geographer

Alaska Volcano Observatory

dstaley@usgs.gov

907-786-7423

#### Jason Kean

##### Research Hydrologist

Landslide Hazards Program

jwkean@usgs.gov

303-273-8608

#### Francis Rengers

##### Research Geologist

Landslide Hazards Program

frengers@usgs.gov

303-273-8637

## Related Content

September 29, 2020

####                 Data supporting an analysis of the recurrence interval of post-fire debris-flow generating rainfall in the southwestern United States              

Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

#### Dennis Michael Staley

##### Geomorphologist, Physical Geographer

Alaska Volcano Observatory

dstaley@usgs.gov

907-786-7423

#### Jason Kean

##### Research Hydrologist

Landslide Hazards Program

jwkean@usgs.gov

303-273-8608

#### Francis Rengers

##### Research Geologist

Landslide Hazards Program

frengers@usgs.gov

303-273-8637

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#### Geologic Hazards Science Center

1711 Illinois St.Golden, CO80401United States

303-273-8500

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