Sediment budget monitoring of a debris-flow torrent (French Prealps)
Détails
ID Serval
serval:BIB_F79AEA384220
Type
Actes de conférence (partie): contribution originale à la littérature scientifique, publiée à l'occasion de conférences scientifiques, dans un ouvrage de compte-rendu (proceedings), ou dans l'édition spéciale d'un journal reconnu (conference proceedings).
Collection
Publications
Institution
Titre
Sediment budget monitoring of a debris-flow torrent (French Prealps)
Titre de la conférence
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment
Editeur
Casa Editrice Università La Sapienza
Organisation
Italian Journal of Engineering Geology and Environment
Statut éditorial
Publié
Date de publication
2011
Editeur⸱rice scientifique
Genevois R., Hamilton D.L., Prestininzi A.
Pages
779-786
Langue
anglais
Notes
Theule2011
Résumé
The Manival near Grenoble (French Prealps) is a very active debris-flow
torrent equipped with a large sediment trap (25 000 m3) protecting
an urbanized alluvial fan from debris-flows. We began monitoring
the sediment budget of the catchment controlled by the trap in Spring
2009. Terrestrial laser scanner is used for monitoring topographic
changes in a small gully, the main channel, and the sediment trap.
In the main channel, 39 cross-sections are surveyed after every event.
Three periods of intense geomorphic activity are documented here.
The first was induced by a convective storm in August 2009 which
triggered a debris-flow that deposited ~1,800 m3 of sediment in the
trap. The debris-flow originated in the upper reach of the main channel
and our observations showed that sediment outputs were entirely supplied
by channel scouring. Hillslope debris-flows were initiated on talus
slopes, as revealed by terrestrial LiDAR resurveys; however they
were disconnected to the main channel. The second and third periods
of geomorphic activity were induced by long duration and low intensity
rainfall events in September and October 2009 which generate small
flow events with intense bedload transport. These events contribute
to recharge the debris-flow channel with sediments by depositing
important gravel dunes propagating from headwaters. The total recharge
in the torrent subsequent to bedload transport events was estimated
at 34% of the sediment erosion induced by the August debris-flow.
torrent equipped with a large sediment trap (25 000 m3) protecting
an urbanized alluvial fan from debris-flows. We began monitoring
the sediment budget of the catchment controlled by the trap in Spring
2009. Terrestrial laser scanner is used for monitoring topographic
changes in a small gully, the main channel, and the sediment trap.
In the main channel, 39 cross-sections are surveyed after every event.
Three periods of intense geomorphic activity are documented here.
The first was induced by a convective storm in August 2009 which
triggered a debris-flow that deposited ~1,800 m3 of sediment in the
trap. The debris-flow originated in the upper reach of the main channel
and our observations showed that sediment outputs were entirely supplied
by channel scouring. Hillslope debris-flows were initiated on talus
slopes, as revealed by terrestrial LiDAR resurveys; however they
were disconnected to the main channel. The second and third periods
of geomorphic activity were induced by long duration and low intensity
rainfall events in September and October 2009 which generate small
flow events with intense bedload transport. These events contribute
to recharge the debris-flow channel with sediments by depositing
important gravel dunes propagating from headwaters. The total recharge
in the torrent subsequent to bedload transport events was estimated
at 34% of the sediment erosion induced by the August debris-flow.
Mots-clé
Debris-flow, bedload transport, sediment budget, terrestrial LiDAR, Manival, French Prealps
Création de la notice
25/11/2013 16:26
Dernière modification de la notice
20/08/2019 16:23
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