Browsing by Autor "Philippe Vauchel"

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A reassessment of the suspended sediment load in the Madeira River basin from the Andes of Peru and Bolivia to the Amazon River in Brazil, based on 10 years of data from the HYBAM monitoring programme
(Elsevier BV, 2017) Philippe Vauchel; William Santini; Jean‐Loup Guyot; Jean‐Sébastien Moquet; Jean-Michel Martínez; Jhan Carlo Espinoza; Patrice Baby; Oscar Fuertes; Luis Noriega; Oscar Puita
Channel and floodplain sediment dynamics in a reach of the tropical meandering Rio Beni (Bolivian Amazonia)
(Wiley, 2010) Erwan Gautier; Daniel Brunstein; Philippe Vauchel; Jean‐Marie Jouanneau; Marc Roulet; Coral García; Jean‐Loup Guyot; Marcello Castro
Abstract The study investigates interactions, water and sediment exchanges, between a rapidly migrating meander and its associated floodplain at fine temporal and spatial scales. The Beni River, an Amazonian free meandering river, makes the transition between Andean ranges and Amazonian lowlands. For the period 2002–2006, an assemblage of tools and methods (water and sediment discharges, topometric and bathymetric surveys, sedimentation rate estimations from unsupported 210 Pb and sediment trapping system) was used to jointly analyse the influence on the sediment budget of external factors (mainly water and sediment discharge) and the inherent behaviour of the system. The main issue addressed is the investigation of the complex relationship between ‘morphological conditioning’ of fluvial landform and process. The first part of the study was undertaken with the aim of linking erosion–deposition in an active meander with water and sediment fluxes. The three inter‐annual evolutions are characterized by very unequal sediment budgets; the first two intervals underwent predominant erosion, and the latter slight accumulation. Digital elevation models, evaluated for the active meander, demonstrate that sedimentation on the point bar depends more on external factors than erosion of the concave bank, which fluctuates slightly. The second part of the study, focusing on water and sediment exchanges between active bend and floodplain, examines the respective parts played by overbank flow and by an abandoned channel on the diffusion and sequestration of sediment. The association of short‐ and long‐term estimation of sedimentation rates suggests that floodplain construction is associated with two different processes and rhythms of sediment transportation. Finally, a sediment budget is proposed for the Beni River in the upper part of the Amazonian lowlands. Copyright © 2010 John Wiley & Sons, Ltd.
Hydroclimatology of the Upper Madeira River basin: spatio-temporal variability and trends
(Taylor & Francis, 2017) Jorge Molina‐Carpio; Jhan Carlo Espinoza; Philippe Vauchel; Josyane Ronchail; Beatriz Emma Gutierrez Caloir; Jean‐Loup Guyot; Luis Noriega
International audience
Inundations in the Mamoré basin (south-western Amazon—Bolivia) and sea-surface temperature in the Pacific and Atlantic Oceans
(Elsevier BV, 2004) Josyane Ronchail; Luc Bourrel; Gérard Cochonneau; Philippe Vauchel; Luis Alejandro Phillips Pedriel; Annibal Castro; Jean‐Loup Guyot; Eurides de Oliveira
Sources of mercury in surface waters of the upper Madeira erosive basins, Bolivia
(Springer Science+Business Media, 2003) Laurence Maurice; L. Alanoca; Pascal Fraizy; Philippe Vauchel
The human activities impact on the mercury (Hg) distribution in the Amazon waters is still discussed but very few information regarding the Hg sources from the highly turbid Andean headwaters have been published. The annual load of suspended sediments eroded from the Bolivian Andes, averages 300x10 6 tons in the Beni river, of which till 97% is exported during the rainy season. At the edge of the Bolivian Andean piedmont, the total Hg concentration vary from 8 ng/l during the dry season, to 1600 ng/l during the high water period. During this stage, it appears that the maximum concentrations of Hg associated with the fine particles and the highest Hg specific fluxes are observed in the rivers exploited for their alluvial gold during the last century. The black-shales series associated to the gold deposits are characterised by high natural Hg contents, which can be released in the hydrographic system by both chemical and physical weathering. But if we compare two clear water rivers characterised by the same suspended sediment concentrations, the maximum specific Hg flux varies between 126 kg/km 2 .j in the pristine river, to 590 kg/km 2 .j in the river characterised by recent human activities.
Temporal relations between meander deformation, water discharge and sediment fluxes in the floodplain of the Rio Beni (Bolivian Amazonia)
(Wiley, 2006) Erwan Gautier; Daniel Brunstein; Philippe Vauchel; M. Roulet; Oscar Fuertes; Jean‐Loup Guyot; J. Darozzes; L. Bourrel
Abstract The Andean Cordillera and piedmont significantly influence river system and dynamics, being the source of many of the important rivers of the Amazon basin. The Beni River, whose upper sub‐catchments drain the Andean and sub‐Andean ranges, is a major tributary of the Madeira River. This study examines the river in the south‐western Amazonian lowlands of Bolivia, where it develops mobile meanders. Channel migration, meander‐bend morphology and ox‐bow lakes are analysed at different temporal and spatial scales. The first part of this study was undertaken with the aim to link the erosion–deposition processes in the active channel with hydrological events. The quantification of annual erosion and deposition areas shows high inter‐annual and spatial variability. In this study, we investigate the conditions of sediment exportation in the river in relation to three hydrological parameters (flood intensity, date of discharge peak and duration of the bank‐full stage level). The second part of this study, focusing on the abandoned meanders, analyses the cutoff processes and the post‐abandonment evolution during 1967–2001. This approach shows the influence of the active channel behaviour on the sediment diffusion and sequestration of the abandoned meanders and allows us to build a first model of the contemporary floodplain evolution. Copyright © 2006 John Wiley & Sons, Ltd.