Morphology and sedimentology of a complex debris flow in a clay‐shale basin |
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| Authors: | Alexandre Remaître Jean-Philippe Malet Olivier Maquaire |
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| Institution: | 1. Institut de Physique du Globe, UMR 7516 CNRS-ULP, 5, rue René Descartes, F-67084 Strasbourg Cedex, France;2. Institut de Physique du Globe, UMR 7516 CNRS-ULP, 5, rue René Descartes, F-67084 Strasbourg Cedex, France
Present address: Faculty of Geosciences, University of Utrecht, PO Box 80.115, 3508 TC Utrecht, The Netherlands. |
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| Abstract: | Coupling morphological, sedimentological, and rheological studies to numerical simulations is of primary interest in defining debris‐flow hazard on alluvial fans. In particular, numerical runout models must be carefully calibrated by morphological observations. This is particularly true in clay‐shale basins where hillslopes can provide a large quantity of poorly sorted solid materials to the torrent, and thus change both the mechanics of the debris flow and its runout distance. In this context, a study has been completed on the Faucon stream (southeastern French Alps), with the objectives of (1) defining morphological and sedimentological characteristics of torrential watersheds located in clay‐shales, and (2) evaluating through a case study the scouring potential of debris flows affecting a clay‐shale basin. Morphological surveys, grain‐size distributions and petrographic analyses of the debris‐flow deposits demonstrate the granular character of the flow during the first hectometre, and its muddy character from there to its terminus on the debris fan. These observations and laboratory tests suggest that the contributing areas along the channel have supplied the bulk of the flow material. Copyright © 2005 John Wiley & Sons, Ltd. |
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| Keywords: | debris flows clay‐shale basin muddy flow granular flow contributing areas |
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