Entrainment and deposition of boulders in a gravel bed river
<p>Bedload transport, entrainment of coarse sediment by a river, is inherently a stochastic and intermittent process whose monitoring remains challenging. Here, we propose a new method to characterize bedload transport in the field. Using an uncrewed aerial vehicle (UAV) equipped with a high-r...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-01-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://esurf.copernicus.org/articles/11/21/2023/esurf-11-21-2023.pdf |
| _version_ | 1797948227625943040 |
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| author | P. Allemand E. Lajeunesse O. Devauchelle V. J. Langlois |
| author_facet | P. Allemand E. Lajeunesse O. Devauchelle V. J. Langlois |
| author_sort | P. Allemand |
| collection | DOAJ |
| description | <p>Bedload transport, entrainment of coarse sediment by a river, is inherently
a stochastic and intermittent process whose monitoring remains challenging.
Here, we propose a new method to characterize bedload transport in the
field. Using an uncrewed aerial vehicle (UAV) equipped with a high-resolution camera, we recorded yearly images of a bar of the Grande Rivière des Vieux-Habitants, a gravel bed river located on Basse-Terre Island (Guadeloupe, French West Indies). These images, combined with high-frequency measurements of the river discharge, allow us to monitor the evolution of the population of sediments of a diameter between 0.5 and 0.75 m on the riverbed. Based on this dataset, we estimate the smallest discharge that can move these boulders and calculate the duration of effective transport. We find that the transport of boulders occurs for approximately 10 h yr<span class="inline-formula"><sup>−1</sup></span>. When plotted as a function of the effective transport time, a given population of boulders decreases exponentially with an effective residence time of approximately 17 h. This exponential decay suggests that the probability of dislodging a grain from the bed is proportional to the number of grains at repose on the bed, an observation consistent with laboratory experiments. Finally, the residence time of bedload particles on a riverbed can be used to evaluate bedload discharge.</p> |
| first_indexed | 2024-04-10T21:39:59Z |
| format | Article |
| id | doaj.art-27c4d3727f29444e99e7deb569d18818 |
| institution | Directory Open Access Journal |
| issn | 2196-6311 2196-632X |
| language | English |
| last_indexed | 2024-04-10T21:39:59Z |
| publishDate | 2023-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Earth Surface Dynamics |
| spelling | doaj.art-27c4d3727f29444e99e7deb569d188182023-01-19T05:19:08ZengCopernicus PublicationsEarth Surface Dynamics2196-63112196-632X2023-01-0111213210.5194/esurf-11-21-2023Entrainment and deposition of boulders in a gravel bed riverP. Allemand0E. Lajeunesse1O. Devauchelle2V. J. Langlois3Université Claude Bernard Lyon 1, ENS Lyon, Université Jean Monnet Saint-Étienne & CNRS, Laboratoire de Géologie de Lyon, Terre Planètes Environnement, UMR 5276, 69100 Villeurbanne, FranceUniversité de Paris, Institut de Physique du Globe de Paris, CNRS, 75005, Paris, FranceUniversité de Paris, Institut de Physique du Globe de Paris, CNRS, 75005, Paris, FranceUniversité Claude Bernard Lyon 1, ENS Lyon, Université Jean Monnet Saint-Étienne & CNRS, Laboratoire de Géologie de Lyon, Terre Planètes Environnement, UMR 5276, 69100 Villeurbanne, France<p>Bedload transport, entrainment of coarse sediment by a river, is inherently a stochastic and intermittent process whose monitoring remains challenging. Here, we propose a new method to characterize bedload transport in the field. Using an uncrewed aerial vehicle (UAV) equipped with a high-resolution camera, we recorded yearly images of a bar of the Grande Rivière des Vieux-Habitants, a gravel bed river located on Basse-Terre Island (Guadeloupe, French West Indies). These images, combined with high-frequency measurements of the river discharge, allow us to monitor the evolution of the population of sediments of a diameter between 0.5 and 0.75 m on the riverbed. Based on this dataset, we estimate the smallest discharge that can move these boulders and calculate the duration of effective transport. We find that the transport of boulders occurs for approximately 10 h yr<span class="inline-formula"><sup>−1</sup></span>. When plotted as a function of the effective transport time, a given population of boulders decreases exponentially with an effective residence time of approximately 17 h. This exponential decay suggests that the probability of dislodging a grain from the bed is proportional to the number of grains at repose on the bed, an observation consistent with laboratory experiments. Finally, the residence time of bedload particles on a riverbed can be used to evaluate bedload discharge.</p>https://esurf.copernicus.org/articles/11/21/2023/esurf-11-21-2023.pdf |
| spellingShingle | P. Allemand E. Lajeunesse O. Devauchelle V. J. Langlois Entrainment and deposition of boulders in a gravel bed river Earth Surface Dynamics |
| title | Entrainment and deposition of boulders in a gravel bed river |
| title_full | Entrainment and deposition of boulders in a gravel bed river |
| title_fullStr | Entrainment and deposition of boulders in a gravel bed river |
| title_full_unstemmed | Entrainment and deposition of boulders in a gravel bed river |
| title_short | Entrainment and deposition of boulders in a gravel bed river |
| title_sort | entrainment and deposition of boulders in a gravel bed river |
| url | https://esurf.copernicus.org/articles/11/21/2023/esurf-11-21-2023.pdf |
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