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The influence of vegetation cover on debris-flow density during an extreme rainfall in the northern Colorado Front Range

Geology

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https://doi.org/10.1130/G38096.1

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Abstract

We explored regional influences on debris-flow initiation throughout the Colorado Front Range (Colorado, USA) by exploiting a unique data set of more than 1100 debris flows that initiated during a 5 day rainstorm in 2013. Using geospatial data, we examined the influence of rain, hillslope angle, hillslope aspect, and vegetation density on debris-flow initiation. In particular we used a greenness index to differentiate areas of high tree density from grass and bare soil. The data demonstrated an overwhelming propensity for debris-flow initiation on south-facing hillslopes. However, when the debris-flow density was analyzed with respect to total rainfall and greenness we found that most debris flows occurred in areas of high rainfall and low tree density, regardless of hillslope aspect. These results indicate that present-day tree density exerts a stronger influence on debris-flow initiation locations than aspect-driven variations in soil and bedrock properties that developed over longer time scales.

Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The influence of vegetation cover on debris-flow density during an extreme rainfall in the northern Colorado Front Range
Series title:
Geology
DOI:
10.1130/G38096.1
Volume:
44
Issue:
10
Year Published:
2016
Language:
English
Publisher:
Geological Society of America
Contributing office(s):
Geologic Hazards Science Center
Description:
4 p.
First page:
823
Last page:
826