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Auteurs :
Lissak, Candide

Description :

International audience

In the frame of SAMCO (ANR 12 SENV-0004) project designed for mountain hazard mitigation in a context ofClimate Change, one of our purposes is to understand the hydro-geomorphological specificities of French Alpinecatchments. Part of our study deals with a better assessment of the sediment transfers, and adjacent sedimentsupply (i.e. from hillslope to channel, and from tributaries to the trunk river) during seasonal meteorologicalevents, and major event inducing floods and/or avalanches. Our research focuses on the Guil River catchment(Queyras, Southern French Alps), prone to catastrophic floods (June 1957 (> R.I. 100 yr), June 2000 (R.I.30 yr)...) with serious damages to infrastructure and buildings located in the valley bottoms. Such floods arecharacterized by considerable sediment transport from debris flow prone tributaries to downvalley, togetherwith strong hillslope-channel connectivity. The “schistes lustrés” bedrock is an aggravating factor that explainsthe mobilization of huge volumes during floods (12,000 m3 aggraded during the June 2000 flood event).Confluences with debris flow prone tributaries are particularly sensitive areas..For monitoring and modelling hydrological and sedimentary processes our approach is twofold: (i) assessment ofslopes contribution to sediment supply using terrestrial laser scanning (TLS), (ii) assessment of two sub-catchmentcontribution to the global sediment budget of the Guil river catchment using passive integrated transponder (PIT)technique. To assess coarse sediment fluxes and delivery into the main channel network, we implemented 560tracers in 4 selected sub-catchments. To assess small sediment delivery, 1 Airborne LiDAR and 2 TLS campaignshave been performed using Optech station over 3 specific hotspots highly affected by slope erosion and largelycontributing to the Guil river sediment budget. The first location corresponds to a gorge section with directconnection of hillslope to the main channel network (Guil River). The second site is located in a sub-catchment,at the confluence of two productive torrents, and the third one is located along a torrent, in a small upstreamsub-catchment. Based on the use of multi resolution data, erosion rates and sedimentary dynamics are presentedas preliminary results. Four other TLS campaigns (2 per years) are planned and aimed at associating erosion ratesto seasonal hydro-climatic conditions to characterize transfers of sediments at the river catchment scale associatedto specific hydro-meteorological conditions.

Mots-clés :
bassin-versant - processus hydrologique - processus sédimentaire - Queyras - Alpes - France - modélisation - [SDU] Sciences of the Universe [physics] - [SDU.STU] Sciences of the Universe [physics]/Earth Sciences - [SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology - [SDU.STU.HY] Sciences of the Universe [physics]/Earth Sciences/Hydrology

Editeur :

Langue :

Type de document :
info:eu-repo/semantics/conferenceObject, Conference papers

Source :
Geophysical Research Abstracts; EGU General Assembly 2015;; EGU General Assembly 2015, Apr 2015, Vienne, Austria. Geophysical Research Abstracts, 17, p. 4944

Date :

Contributeurs :
Littoral, Environnement, Télédétection, Géomatique (LETG - Caen) ; Littoral, Environnement, Télédétection, Géomatique (LETG) ; Université Caen Normandie (UNICAEN) - Université d'Angers (UA) - Université de Nantes (UN) - École pratique des hautes études (EPHE) - Université de Brest (UBO) - Université de Rennes 2 (UR2) - Centre National de la Recherche Scientifique (CNRS) - Université Caen Normandie (UNICAEN) - Université d'Angers (UA) - Université de Nantes (UN) - École pratique des hautes études (EPHE) - Université de Brest (UBO) - Université de Rennes 2 (UR2) - Centre National de la Recherche Scientifique (CNRS)
Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG) ; Université Panthéon-Sorbonne (UP1) - Institut de Recherche pour le Développement (IRD) - École pratique des hautes études (EPHE) - Université Paris-Sorbonne (UP4) - AgroParisTech - Université Paris Diderot - Paris 7 (UPD7) - Centre National de la Recherche Scientifique (CNRS)
Institut de physique du globe de Strasbourg (IPGS) ; Institut national des sciences de l'Univers (INSU - CNRS) - Université de Strasbourg - Centre National de la Recherche Scientifique (CNRS)
Université Paris Diderot - Paris 7 (UPD7)
ANR-12-SENV-0004, SAMCO, Adaptation de la société aux risques en montagne dans un contexte de changement global(2012)

Identifiants :

Couverture :

Vienne, Austria