A rationale for effective post-fire debris flow mitigation within forested terrain

Abstract Watersheds recently burned by wildfires are recognized as having an increased susceptibility to debris flow occurrence. The great majority occur within the first 2 years following wildfires. These debris flows are generated primarily through the process of progressive entrainment of materia...

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Main Author: Jerome V. De Graff
Format: Article
Language:English
Published: SpringerOpen 2018-05-01
Series:Geoenvironmental Disasters
Subjects:
Online Access:http://link.springer.com/article/10.1186/s40677-018-0099-z
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author Jerome V. De Graff
author_facet Jerome V. De Graff
author_sort Jerome V. De Graff
collection DOAJ
description Abstract Watersheds recently burned by wildfires are recognized as having an increased susceptibility to debris flow occurrence. The great majority occur within the first 2 years following wildfires. These debris flows are generated primarily through the process of progressive entrainment of material eroded from hillslopes and channels by surface runoff and appears independent of the vegetative community burned. The decreased likelihood of debris flows over time is linked to the restoration of hydrologic function as vegetative cover and soil infiltration functioning return to pre-fire conditions. An exception to this pattern of post-wildfire debris flow susceptibility occurs in burned drainage basins with forest cover. A second, later period of increased debris flow susceptibility due to infiltration-triggered landslides can occur in burned forested basins. This later period of debris flow susceptibility is largely attributable to the fire-induced tree mortality and subsequent decay of tree root networks decreasing soil strength on steep hillslopes which produces an increased likelihood of debris flow occurrence 3 to 10 or more years after the wildfire. Consequently, post-fire mitigation measures in forested terrain must address the risk posed by debris flows caused by progressive entrainment during the 2 years following the wildfire and debris flows due to infiltration-induced debris slides three or more years later. Mitigation for the later debris flows in forested terrain involves identification of areas with infiltration-induced debris slides coincident with concentrations of fire-killed trees. Timely reforestation of these areas after a wildfire limits the loss of soil strength from decaying roots.
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spelling doaj.art-536aedb036c54b45aba96c946c07d8212022-12-22T03:11:15ZengSpringerOpenGeoenvironmental Disasters2197-86702018-05-01511910.1186/s40677-018-0099-zA rationale for effective post-fire debris flow mitigation within forested terrainJerome V. De Graff0Department of Earth & Environmental Science, California State UniversityAbstract Watersheds recently burned by wildfires are recognized as having an increased susceptibility to debris flow occurrence. The great majority occur within the first 2 years following wildfires. These debris flows are generated primarily through the process of progressive entrainment of material eroded from hillslopes and channels by surface runoff and appears independent of the vegetative community burned. The decreased likelihood of debris flows over time is linked to the restoration of hydrologic function as vegetative cover and soil infiltration functioning return to pre-fire conditions. An exception to this pattern of post-wildfire debris flow susceptibility occurs in burned drainage basins with forest cover. A second, later period of increased debris flow susceptibility due to infiltration-triggered landslides can occur in burned forested basins. This later period of debris flow susceptibility is largely attributable to the fire-induced tree mortality and subsequent decay of tree root networks decreasing soil strength on steep hillslopes which produces an increased likelihood of debris flow occurrence 3 to 10 or more years after the wildfire. Consequently, post-fire mitigation measures in forested terrain must address the risk posed by debris flows caused by progressive entrainment during the 2 years following the wildfire and debris flows due to infiltration-induced debris slides three or more years later. Mitigation for the later debris flows in forested terrain involves identification of areas with infiltration-induced debris slides coincident with concentrations of fire-killed trees. Timely reforestation of these areas after a wildfire limits the loss of soil strength from decaying roots.http://link.springer.com/article/10.1186/s40677-018-0099-zEmergency responseDebris flowsTimingWildfireTree roots
spellingShingle Jerome V. De Graff
A rationale for effective post-fire debris flow mitigation within forested terrain
Geoenvironmental Disasters
Emergency response
Debris flows
Timing
Wildfire
Tree roots
title A rationale for effective post-fire debris flow mitigation within forested terrain
title_full A rationale for effective post-fire debris flow mitigation within forested terrain
title_fullStr A rationale for effective post-fire debris flow mitigation within forested terrain
title_full_unstemmed A rationale for effective post-fire debris flow mitigation within forested terrain
title_short A rationale for effective post-fire debris flow mitigation within forested terrain
title_sort rationale for effective post fire debris flow mitigation within forested terrain
topic Emergency response
Debris flows
Timing
Wildfire
Tree roots
url http://link.springer.com/article/10.1186/s40677-018-0099-z
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AT jeromevdegraff rationaleforeffectivepostfiredebrisflowmitigationwithinforestedterrain