Evrard O., Navratil Oldrich, Ayrault S., Ahmadi M., Nemery Julien, Legout C., Lefevre I., Poirel A., Bonte P., Esteves Michel. (2011). Combining suspended sediment monitoring and fingerprinting to determine the spatial origin of fine sediment in a mountainous river catchment. Earth Surface Processes and Landforms, 36 (8), p. 1072-1089. ISSN 0197-9337.
Titre du document
Combining suspended sediment monitoring and fingerprinting to determine the spatial origin of fine sediment in a mountainous river catchment
Année de publication
2011
Auteurs
Evrard O., Navratil Oldrich, Ayrault S., Ahmadi M., Nemery Julien, Legout C., Lefevre I., Poirel A., Bonte P., Esteves Michel
Source
Earth Surface Processes and Landforms, 2011,
36 (8), p. 1072-1089 ISSN 0197-9337
An excess of fine sediment (grain size <2 mm) supply to rivers leads to reservoir siltation, water contamination and operational problems for hydroelectric power plants in many catchments of the world, such as in the French Alps. These problems are exacerbated in mountainous environments characterized by large sediment exports during very short periods. This study combined river flow records, sediment geochemistry and associated radionuclide concentrations as input properties to a Monte Carlo mixing model to quantify the contribution of different geologic sources to river sediment. Overall, between 2007 and 2009, erosion rates reached 249 +/- 75 t km(-2) yr(-1) at the outlet of the Bleone catchment, but this mean value masked important spatial variations of erosion intensity within the catchment (85-5000 t km(-2) yr(-1)). Quantifying the contribution of different potential sources to river sediment required the application of sediment fingerprinting using a Monte Carlo mixing model. This model allowed the specific contributions of different geological sub-types (i.e. black marls, marly limestones, conglomerates and Quaternary deposits) to be determined. Even though they generate locally very high erosion rates, black marls supplied only a minor fraction (5-20%) of the fine sediment collected on the riverbed in the vicinity of the 907 km(2) catchment outlet. The bulk of sediment was provided by Quaternary deposits (21-66%), conglomerates (3-44%) and limestones (9-27%). Even though bioengineering works conducted currently to stabilize gullies in black marl terrains are undoubtedly useful to limit sediment supply to the Bleone river, erosion generated by other substrate sources dominated between 2007 and 2009 in this catchment.
Plan de classement
Hydrologie [062]
;
Géologie et formations superficielles [064]
Localisation
Fonds IRD [F B010053640]
Identifiant IRD
fdi:010053640
