Sediment budget monitoring of a debris-flow torrent (French Prealps)
Details
Serval ID
serval:BIB_F79AEA384220
Type
Inproceedings: an article in a conference proceedings.
Collection
Publications
Institution
Title
Sediment budget monitoring of a debris-flow torrent (French Prealps)
Title of the conference
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment
Publisher
Casa Editrice Università La Sapienza
Organization
Italian Journal of Engineering Geology and Environment
Publication state
Published
Issued date
2011
Editor
Genevois R., Hamilton D.L., Prestininzi A.
Pages
779-786
Language
english
Notes
Theule2011
Abstract
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.
Keywords
Debris-flow, bedload transport, sediment budget, terrestrial LiDAR, Manival, French Prealps
Create date
25/11/2013 16:26
Last modification date
20/08/2019 16:23
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