An opportunity to connect the morphodynamics of alternate bars with their sedimentary products |
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| Authors: | Stephane Rodrigues Nicolas Claude Philippe Juge Jean‐Gabriel Breheret |
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| Institution: | 1. Université Fran?ois Rabelais de Tours, CNRS/INSU, Institut des Sciences de la Terre d'Orléans, UMR 6113, UFR des Sciences et Techniques, Parc de Grandmont, , 37200 Tours, France;2. Université Fran?ois Rabelais de Tours, CETU ELMIS, Centre Universitaire de Chinon, , 37500 Chinon, France |
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| Abstract: | Field investigations that help clarify local sedimentary processes involved in the migration of alternate bars as a consequence of flood events are lacking. A simple approach combining scour chains, stratigraphy and frequent bathymetric surveys is proposed to connect the dynamics of free migrating alternate bars present in disconnected channels of large sandy‐gravelly rivers with their sedimentary products and vice versa. The results show that the spatial distribution of bars before a flood partly governs the scour and fill processes and that the sediment transport rates vary significantly on a single cross‐section. This can be due to preferential axes of the migration of the bars determined by their location on the cross‐section, the bank direction and the discharge. The approach allows the reconstruction of local sedimentary processes involved in alternate bar migration by combining maximum scour depths reached during a flood with frequent channel bed topography surveys and post‐flood stratigraphy. It is also possible to distinguish deposited and preserved sediments compared with sediments by‐passed during the flood. Copyright © 2011 John Wiley & Sons, Ltd. |
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| Keywords: | alternate bars field study sequential channel bed topography bedload transport scour chains stratigraphy Loire River flood |
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