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Auteurs :
Viel, Vincent

Description :

International audience

Quantification and characterization of hydrological and sedimentary transfers are now major challenges to preserving European soils and water resources (Law on Water, Water Framework Directive). In northwestern France, stream water quality is currently reduced by suspended sediment. However, in these low-energy water systems, sediment origin and dynamics into the catchment remain difficult to analyze from a local to a regional scale because of intermediary traps caused by landscape structure (hedgerow areas) and land use organization on the slopes. To provide a better understanding of sediment dynamics in these systems we proposed to analyze runoff dynamics on slopes and to assess slopes' contribution to the sediment budget of a catchment. This study is based on sediment connectivity analysis, used to accurately determine runoff dynamics between producing areas and the outlet of the catchment. This work is focused on the Lingèvres catchment (15 km2), a typical feature of the low-energy water system located in the western part of France, in between open-field and bocage landscapes. The results demonstrate that in a hedgerow landscape, known for its protective role against runoff connection to the river, sediment delivery from slopes is more important and efficient than in an open-field area where no obstacles are observed. This is explained by diverse drainage densities and spatial organization of roads, and ditch and plot entries which induced differentiated sediment delivery from agricultural plots and the river. However, they also underlined the weakness of sediment delivery from slopes compared with sediment fluxes exported from the catchment. Conversely, they highlight the fundamental role of erosion processes due to agricultural practices and landscape organization in headwater systems, which seem to be the main functional area at the sub-catchment scale.



Mots-clés :
slope erosion - sediment connectivity - sediment yield - headwater systems - drainage density - [SDU.STU.GM] Sciences of the Universe [physics]/Earth Sciences/Geomorphology

Editeur :
HAL CCSD, Wiley

Langue :
en

Type de document :
info:eu-repo/semantics/article, Journal articles

Source :
ISSN: 0435-3676; EISSN: 1468-0459; Geografiska Annaler: Series A, Physical Geography; https://hal.archives-ouvertes.fr/hal-01291601; Geografiska Annaler: Series A, Physical Geography, Wiley, 2014, Sedimentary fluxes and budgets in different climatic environments, 93 (4), pp.497-511

Date :
2014-12

Contributeurs :
Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG) ; Institut de Recherche pour le Développement (IRD) - Université Paris-Sorbonne (UP4) - École pratique des hautes études (EPHE) - Université Paris Diderot - Paris 7 (UP7) - AgroParisTech (AgroParisTech) - Centre National de la Recherche Scientifique (CNRS) - Université Panthéon-Sorbonne (UP1)
Littoral, Environnement, Télédétection, Géomatique (LETG) ; Université d'Angers (UA) - Université de Nantes (UN) - Université de Caen Basse-Normandie - Université de Bretagne Occidentale (UBO) - Université Rennes 2 - Centre National de la Recherche Scientifique (CNRS)

Identifiants :
hal-01291601
https://hal.archives-ouvertes.fr/hal-01291601