Development and maintenance of a telescoping debris flow fan in response to human-induced fan surface channelization, Chalk Creek Valley Natural Debris Flow Laboratory, Colorado, USA

Wasklewicz, Thad; Scheinert, Cal R.

doi:10.1016/j.geomorph.2015.06.033

Cited by 23 publications

(23 citation statements)

References 78 publications

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“…There has been no systematic survey of field-scale avulsion behavior, however, so such comparisons remain tentative at best. While spatio-temporal patterns of deposition on a few debris-flow fans have been monitored [Suwa and Okuda, 1983;Wasklewicz and Scheinert, 2016;Imaizumi et al, 2016] or reconstructed [e.g., Helsen et al, 2002;Dühnforth et al, 2008;Stoffel et al, 2008;Procter et al, 2012;Zaginaev et al, 2016], the observed patterns have not been quantitatively compared to infer general trends. There has also been little consideration to date of flow routing on debris-flow fans.…”

Section: Introductionmentioning

confidence: 99%

Avulsions and the spatio-temporal evolution of debris-flow fans

Haas

Densmore

Stoffel

et al. 2018

Earth-Science Reviews

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Section: Introductionmentioning

confidence: 99%

Avulsions and the spatio-temporal evolution of debris-flow fans

Haas

Densmore

Stoffel

et al. 2018

Earth-Science Reviews

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“…, ). One outstanding issue is that the spatio‐temporal patterns of deposition on debris‐flow fans have been monitored (Suwa and Okuda, ; Wasklewicz and Scheinert, ; Imaizumi et al. ) or reconstructed (e.g.…”

Section: Introductionmentioning

confidence: 99%

Effects of debris‐flow magnitude–frequency distribution on avulsions and fan development

Haas

Kruijt

Densmore

2018

Earth Surf Processes Landf

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Shifts in the active channel on a debris-flow fan, termed avulsions, pose a large threat because new channels can bypass mitigation measures and cause damage to settlements and infrastructure. Recent, but limited, field evidence suggests that avulsion processes and tendency may depend on the flow-size distribution, which is difficult to constrain in the field. Here, we investigate how the flow magnitude-frequency distribution and the associated flow-magnitude sequences affect avulsion on debris-flow fans. We created three experimental fans with contrasting flow-size distributions: (1) a uniform distribution; (2) a steep double-Pareto distribution with many flows around the mean and a limited number of large flows; and (3) a shallow double-Pareto distribution with fewer flows around the mean and more abundant large flows. The fan formed by uniform flows developed through regular sequences of stepwise channelization, backstepping of deposition toward the fan apex, and avulsion over multiple flows. In contrast, the wide range of sizes in the double-Pareto distributions led to distinct avulsion mechanisms and fan evolution. Here, large flows could overtop channels, creating levee breaches that could initiate avulsion immediately or in subsequent events. Moreover, sequences of small-to moderate-sized flows could deposit channel plugs, triggering avulsion in the next large flow. This mechanism was most common on the fan formed by a steep double-Pareto distribution but was rare on the fan formed by a shallow double-Pareto distribution, where large flows were more frequent. We infer that some flow-size distributions are more likely to cause avulsions -especially those that produce abundant sequences of small flows followed by a large flow. Critically, avulsions in our experiments could occur by either large single events or over multiple flows. This observation has important implications for hazard assessment on debris-flow fans, suggesting that attention should be paid to flow history as well as flow size.

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“…Six TLS surveys were carried out at the study site (May 2011, May 2012, October 2012, May 2013, October 2013 and May 2014) using a Leica HDS C-10 tripod mounted scanner and following techniques documented in several previous studies (Staley et al, 2011(Staley et al, , 2014Scheinert et al, 2012;Wester et al, 2014;Wasklewicz and Scheinert, 2016). Leica HDS planar targets allow data collected at multiple scan positions in each of the field surveys to become seamlessly integrated into one point cloud through the registration process in Leica's Cyclone software.…”

Section: Data Collection and Uncertaintymentioning

confidence: 99%

“…in ArcGIS to depict the patterns of erosion and deposition across the two zones of interest (Staley et al, 2011(Staley et al, , 2014Scheinert et al, 2012;Wester et al, 2014;Wasklewicz and Scheinert, 2016).…”

Section: Geomorphic Change Detectionmentioning

confidence: 99%

Three years of morphologic changes at a bowl blowout, Cape Cod, USA

Smith¹,

Garès

Wasklewicz

et al. 2017

Geomorphology

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This study presents measurements of blowout topography obtained with annual terrestrial laser surveys carried out over a three-year period at a single, large bowl blowout located in the Provincelands Dunes section of Cape Cod National Seashore, in Massachusetts. The study blowout was selected because its axis is aligned with northwest winds that dominate the region, and because it was seemingly interacting with a smaller saucer blowout that had recently formed on the southern rim of the primary feature. Assuming that blowouts enlarge both horizontally and vertically in response to the wind regime, the objectives of the study were to determine both the amount of horizontal growth that the blowout experiences annually and the spatial patterns of vertical change that occur within the blowout. Changes to the blowout lobe surrounding the feature were also determined for areas with sparse enough vegetation cover to allow laser returns from the sand surface. The results show that the blowout consistently expanded outward during the three years, with the greatest expansion occurring at its southeast corner, opposite the prevailing winds. The most significant occurrence was the removal, in the first year, of the ridge that separated the two blowouts, resulting in a major horizontal shift of the southern rim of the new combined blowout. This displacement then continued at a lesser rate in subsequent years. The rim also shifted horizontally along the northwest to northeast sections of the blowout. Significant vertical loss occurred along the main axis of the blowout with the greatest loss concentrated along the southeast rim. On the lobe, there were large areas of deposition immediately downwind of the high erosion zones inside the blowout. However, there were also small erosion areas on the lobe, extending downwind from eroding sections of the rim. This study shows that: 1. blowouts can experience significant areal and volumetric changes in short periods of time; 2. significant changes may occur relatively suddenly when adjacent blowouts combine into a single feature; and 3. the sediment transport paths are highly controlled by the topography. The joining of two blowouts not only creates a new larger feature, but it also releases large amounts of sediment that are then distributed across the landscape downwind, creating a potential for major changes to a landscape over the longer term.

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Development and maintenance of a telescoping debris flow fan in response to human-induced fan surface channelization, Chalk Creek Valley Natural Debris Flow Laboratory, Colorado, USA

Cited by 23 publications

References 78 publications

Avulsions and the spatio-temporal evolution of debris-flow fans

Avulsions and the spatio-temporal evolution of debris-flow fans

Effects of debris‐flow magnitude–frequency distribution on avulsions and fan development

Three years of morphologic changes at a bowl blowout, Cape Cod, USA

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