Les torrents de l'Arve

The example of torrents from the Arve basin was used to analyse the sediment dynamics of the torrential system. They are caracterised by two periods : first, a long period of sediment accumulation in the channel. Sediments on slopes are carried by a series of linked processes (landslides, avalanches, rock-falls...); secondly, a very brief period of sediment transportation during debris-flows, which displace large volumes of sediments and change considerably the channel morphology (channel incision, lateral erosion...). It appears that the intensity of the sediment accumulation in channels controls the frequency of debris-flows. A classification of torrents, based on the origin of the sediment accumulated in channels, is proposed. In a second part, the study presents improvement works made on torrents since the end of the 19th century (reforestation, long-profile stabilisation, building of sediment storage areas...). These improvement works were responsible for a decrease of sediment inputs into the torrential system; therefore, torrents were more stable and debris-flows were less frequent. Sediment inputs into the Arve river were reduced; since 1950, this tendency has been increased by the development of gravel extraction on alluvial fans

Alluvial fan · Alluvium · Channel (broadcasting) · Debris · Drainage basin · Erosion · Geography · Geomorphology · Geotechnical engineering · Hydrology (agriculture) · Landslide · Sediment · Sediment transport · Sedimentary budget · Structural basin · Geology · Geology and Paleoclimatology Research · Landslides and related hazards · Oceanography · Soil erosion and sediment transport

• Soil erosion in small catchments of the Quercy region (southwester France) during the Holocene

  Open Access•Pascal Bertran•The Holocene•2004

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