The influence of large woody debris on post-wildfire debris flow sediment storage

Natural Hazards and Earth System Sciences
By: , and 



Debris flows transport large quantities of water and granular material, such as sediment and wood, and this mixture can have devastating impacts on life and infrastructure. The proportion of large woody debris (LWD) incorporated into debris flows can be enhanced in forested areas recently burned by wildfire, because wood recruitment into channels accelerates in burned forests. In this study, we explored how LWD transported in post-wildfire debris flows acts to retain sediment within small headwater channels. We found that the largest amount of debris flow sediment is stored in channel reaches with a ratio of LWD length to channel width between 0.25 and 1. Moreover, the largest debris flow deposits forced by LWD were found in low-angle channel reaches. We examined two models for debris flow volume estimation: (1) the current volume prediction model used in U.S. Geological Survey debris flow hazard assessments, and (2) a regional model developed to predict the sediment yield associated with debris-laden flows. We found that the regional model better matched the magnitude of the observed sediment at the terminal fan, suggesting the utility of regionally calibrated parameters for debris flow volume prediction. However, large wood created sediment storage upstream of the terminal fan, and this volume was of the same magnitude as the total volume at the terminal fans. Finally, we demonstrate a method for estimating debris flow velocity based on estimates of the critical velocity required to break wood, which can be used in future field studies to estimate minimum debris flow velocity values.

Study Area

Publication type Article
Publication Subtype Journal Article
Title The influence of large woody debris on post-wildfire debris flow sediment storage
Series title Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-23-2075-2023
Volume 23
Issue 6
Year Published 2023
Language English
Publisher European Geosciences Union
Contributing office(s) Geologic Hazards Science Center
Description 14 p.
First page 2075
Last page 2088
Country United States
State New Mexico
Other Geospatial Gila National Forest
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