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Probability and volume of potential postwildfire debris flows in the 2011 Wallow burn area, eastern Arizona

Open-File Report 2011-1214

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Abstract

This report presents a preliminary emergency assessment of the debris-flow hazards from drainage basins burned in 2011 by the Wallow wildfire in eastern Arizona. Empirical models derived from statistical evaluation of data collected from recently burned drainage basins throughout the intermountain western United States were used to estimate the probability of debris-flow occurrence and debris-flow volumes for selected drainage basins. Input for the models include measures of burn severity, topographic characteristics, soil properties, and rainfall total and intensity for a (1) 10-year-recurrence, 1-hour-duration rainfall and (2) 25-year-recurrence, 1-hour-duration rainfall. Estimated debris-flow probabilities in the drainage basins of interest ranged from less than 1 percent in response to both the 10-year-recurrence, 1-hour-duration rainfall and the 25-year-recurrence, 1-hour-duration rainfall to a high of 41 percent in response to the 25-year-recurrence, 1-hour-duration rainfall. The low probabilities in all modeled drainage basins are likely due to extensive low-gradient hillslopes, burned at low severities, and large drainage-basin areas (greater than 25 square kilometers). Estimated debris-flow volumes ranged from a low of 24 cubic meters to a high of greater than 100,000 cubic meters, indicating a considerable hazard should debris flows occur

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Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Probability and volume of potential postwildfire debris flows in the 2011 Wallow burn area, eastern Arizona
Series title:
Open-File Report
Series number:
2011-1214
Year Published:
2011
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Colorado Water Science Center
Description:
iv, 11 p.
State:
Arizona
Online Only (Y/N):
Y