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Open-File Report 2011–1248

Prepared in cooperation with the Colorado Department of Transportation

Probability and Volume of Potential Postwildfire Debris Flows in the 2011 Indian Gulch Burn Area, near Golden, Colorado

By Barbara C. Ruddy

Thumbnail of and link to report PDF (30.3 MB)Abstract

This report presents an assessment of the debris-flow hazards from drainage basins burned in 2011 by the Indian Gulch wildfire near Golden, Colorado. 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) 2-year-recurrence, 1-hour-duration rainfall, (2) 10-year-recurrence, 1-hour-duration rainfall, and (3) 25-year-recurrence, 1-hour-duration rainfall.

Estimated debris-flow probabilities in the drainage basins of interest ranged from 2 percent in response to the 2-year-recurrence, 1-hour-duration rainfall to a high of 76 percent in response to the 25-year-recurrence, 1-hour-duration rainfall. Estimated debris-flow volumes ranged from a low of 840 cubic meters to a high of 26,000 cubic meters, indicating a considerable hazard should debris flows occur.

First posted September 29, 2011

For additional information contact:
Center Director, USGS Colorado Water Science Center
Box 25046, Mail Stop 415
Denver, CO 80225

http://co.water.usgs.gov

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Suggested citation:

Ruddy, B.C., 2011, Probability and volume of potential postwildfire debris flows in the 2011 Indian Gulch burn area, near Golden, Colorado: U.S. Geological Survey Open-File Report 2011–1248, 15 p.



Contents

Abstract

Introduction

Estimated Debris-Flow Probabilities and Volumes

Use and Limitations of the Assessment

References Cited


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