Debris flow initiation and sediment recharge in gullies |
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| Authors: | Drew Brayshaw Marwan A Hassan |
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| Institution: | aDepartment of Forest Resources Management, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, Canada V6T 1Z4;bDepartment of Geography, University of British Columbia, 1984 West Mall, Vancouver, British Columbia, Canada V6T 1Z2 |
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| Abstract: | Landslides that enter gullied low-order drainages can either initiate debris flow or stop, depositing sediment in the channel. This process is one of the most common ways that debris flows initiate, but little attention to date has been paid to evaluating the factors that affect whether or not the initial landslide will become a debris flow or deposit sediment in the channel. Statistically significant parameters that determine whether slope failures become debris flows or act to recharge in-channel sediment are channel gradient, angle of entry of failure into the channel, initial failure volume, and the amount of in-channel stored sediment. Steeper channels, low angles of entry, lower volumes of in-channel sediment, and larger initial failures were more likely to result in debris flows. This study found that as the volume of in-channel stored sediment increased, the volume of initial failure required to initiate a debris flow also increased. This result calls into question the simple supply-limited model of cyclical debris recharge and debris flow in low-order gullied drainages and suggests a negative feedback mechanism between debris accumulation and debris flow susceptibility. |
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| Keywords: | Debris flow Debris slide Gully Landslide Sedimentation |
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