A robust method to identify the occurrence of a runoff-generated debris flow
Debris flows generated by rainfall runoff can occur in rocky alpine landscapes and burned steeplands. Runoff-generated debris-flow events are commonly composed of a series of dense granular surge fronts separated by water-rich flows. Owing to this intra-event variability in flow composition and mech...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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EDP Sciences
2023-01-01
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| Series: | E3S Web of Conferences |
| Online Access: | https://www.e3s-conferences.org/articles/e3sconf/pdf/2023/52/e3sconf_dfhm82023_01013.pdf |
| _version_ | 1797740279889920000 |
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| author | McCoy Scott W. Cavagnaro David B. Kean Jason W. Thomas Matthew A. Lindsay Donald N. |
| author_facet | McCoy Scott W. Cavagnaro David B. Kean Jason W. Thomas Matthew A. Lindsay Donald N. |
| author_sort | McCoy Scott W. |
| collection | DOAJ |
| description | Debris flows generated by rainfall runoff can occur in rocky alpine landscapes and burned steeplands. Runoff-generated debris-flow events are commonly composed of a series of dense granular surge fronts separated by water-rich flows. Owing to this intra-event variability in flow composition and mechanics, post-event interpretations of preserved sedimentary deposits, or lack thereof, can result in a dizzying mix of interpretations that range from clearwater flow to debris flow. Accurate identification of the presence or absence of a debris flow during a runoff event is critical for building empirical models used to predict likelihood of debris-flow occurrence, rainfall thresholds, and flow properties. Here, we propose a simple, quantitative method to identify the occurrence of a runoff-generated debris flow, based on a dimensionless discharge Q* calculated as the ratio of the peak event discharge Qp to the theoretical maximum clearwater runoff rate Qw. Using a preliminary compilation of Q* values from floods and runoff-generated debris flows, we find 98% of floods have Q* values < 1.6, whereas 91% of debris flows have Q* values greater than 1.6. Estimating Q* is typically straightforward as part of standard post-event reconnaissance if suitable rainfall estimates are available, and appears to be a robust indicator that runoff-generated debris flows traversed a particular portion of a valley network. |
| first_indexed | 2024-03-12T14:10:11Z |
| format | Article |
| id | doaj.art-ec798a76842a4fa0b6b5c9ec5aebdb4c |
| institution | Directory Open Access Journal |
| issn | 2267-1242 |
| language | English |
| last_indexed | 2024-03-12T14:10:11Z |
| publishDate | 2023-01-01 |
| publisher | EDP Sciences |
| record_format | Article |
| series | E3S Web of Conferences |
| spelling | doaj.art-ec798a76842a4fa0b6b5c9ec5aebdb4c2023-08-21T09:02:29ZengEDP SciencesE3S Web of Conferences2267-12422023-01-014150101310.1051/e3sconf/202341501013e3sconf_dfhm82023_01013A robust method to identify the occurrence of a runoff-generated debris flowMcCoy Scott W.0Cavagnaro David B.1Kean Jason W.2Thomas Matthew A.3Lindsay Donald N.4Department of Geological Sciences and Engineering, University of NevadaDepartment of Geological Sciences and Engineering, University of NevadaLandslide Hazards Program, United States Geological SurveyLandslide Hazards Program, United States Geological SurveyCalifornia Geological SurveyDebris flows generated by rainfall runoff can occur in rocky alpine landscapes and burned steeplands. Runoff-generated debris-flow events are commonly composed of a series of dense granular surge fronts separated by water-rich flows. Owing to this intra-event variability in flow composition and mechanics, post-event interpretations of preserved sedimentary deposits, or lack thereof, can result in a dizzying mix of interpretations that range from clearwater flow to debris flow. Accurate identification of the presence or absence of a debris flow during a runoff event is critical for building empirical models used to predict likelihood of debris-flow occurrence, rainfall thresholds, and flow properties. Here, we propose a simple, quantitative method to identify the occurrence of a runoff-generated debris flow, based on a dimensionless discharge Q* calculated as the ratio of the peak event discharge Qp to the theoretical maximum clearwater runoff rate Qw. Using a preliminary compilation of Q* values from floods and runoff-generated debris flows, we find 98% of floods have Q* values < 1.6, whereas 91% of debris flows have Q* values greater than 1.6. Estimating Q* is typically straightforward as part of standard post-event reconnaissance if suitable rainfall estimates are available, and appears to be a robust indicator that runoff-generated debris flows traversed a particular portion of a valley network.https://www.e3s-conferences.org/articles/e3sconf/pdf/2023/52/e3sconf_dfhm82023_01013.pdf |
| spellingShingle | McCoy Scott W. Cavagnaro David B. Kean Jason W. Thomas Matthew A. Lindsay Donald N. A robust method to identify the occurrence of a runoff-generated debris flow E3S Web of Conferences |
| title | A robust method to identify the occurrence of a runoff-generated debris flow |
| title_full | A robust method to identify the occurrence of a runoff-generated debris flow |
| title_fullStr | A robust method to identify the occurrence of a runoff-generated debris flow |
| title_full_unstemmed | A robust method to identify the occurrence of a runoff-generated debris flow |
| title_short | A robust method to identify the occurrence of a runoff-generated debris flow |
| title_sort | robust method to identify the occurrence of a runoff generated debris flow |
| url | https://www.e3s-conferences.org/articles/e3sconf/pdf/2023/52/e3sconf_dfhm82023_01013.pdf |
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