Channel and floodplain sediment dynamics in a reach of the tropical meandering Rio Beni (Bolivian Amazonia)
Article first published online: 28 SEP 2010
Copyright © 2010 John Wiley & Sons, Ltd.
Earth Surface Processes and Landforms
Volume 35, Issue 15, pages 1838–1853, December 2010
How to Cite
Gautier, E., Brunstein, D., Vauchel, P., Jouanneau, J.-M., Roulet, M., Garcia, C., Guyot, J.-L. and Castro, M. (2010), Channel and floodplain sediment dynamics in a reach of the tropical meandering Rio Beni (Bolivian Amazonia). Earth Surf. Process. Landforms, 35: 1838–1853. doi: 10.1002/esp.2065
- Issue published online: 1 DEC 2010
- Article first published online: 28 SEP 2010
- Manuscript Accepted: 21 JUN 2010
- Manuscript Revised: 7 JUN 2010
- Manuscript Received: 14 JAN 2009
- floodplain construction;
- sediment budget;
- Beni River;
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 210Pb 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.