HR: 1340h
AN: H33C-1401    [Abstracts]
TI: Numerical Modeling of the Channelling Granular Flows and the Formation of Levees Observed on the Earth and on Mars Surface
AU: * Mangeney, A
EM: mangeney@ipgp.jussieu.fr
AF: Département de Modélisation Physique et Numérique, GREEC, IPGP, 4, Place Jussieu, Paris, 75005 France
AU: Bouchut, F
EM: Francois.Bouchut@ens.fr
AF: Département de Mathématique et Applications, Ecole Normale Supérieure et CNRS, 45 rue d'Ulm, Paris, 75005 France
AU: Thomas, N
EM: nathalie.thomas@polytech.univ-mrs.fr
AF: Institut Universitaire des Systémes Thermiques Industriels, Technopole de Chateau-Gombert, 5 rue Enrico Fermi, Marseille, 13453 France
AU: Vilotte, J
EM: vilotte@ipgp.jussieu.fr
AF: Département de Modélisation Physique et Numérique, GREEC, IPGP, 4, Place Jussieu, Paris, 75005 France
AB: Gravitational granular flows occur both on the Earth surface and on other telluric planets. Several features such as the high mobility of avalanches or the presence of levées in the deposit of geophysical granular flows are observed on Earth as well as on Mars or on the moon. The similarities observed on avalanche deposits on Mars and on the Earth provides a unique opportunity to study gravitational processes under different gravities. The numerical simulation of gravitational flows should provide a useful tool for investigating the geomorphologic processes on telluric planets. When not laterally confined in valleys, pyroclastic flows on the earth surface as well as lanslides on Mars propagate as a tongue shape flow with sub-parallel borders, creating their own channel along a slope by selecting a flowing width. Furthermore, the lobe shaped deposits display a very specific morphology with high parallel lateral levées. The existence of these raised levees bordering the channel on Martian landslide deposit have been first interpreted as indicating the presence of water during emplacement. However, these deposits may be explained only by referring to dry granular flows. We use here a numerical model based on a Saint-Venant model and a Coulomb type behavior to simulate the unconfined granular flow over an inclined plane under constant supply. Numerical simulation are shown to be able to reproduce the auto-chenalization of the granular lobe and the formation of levée channel morphology. As a result this phenomenon is expected to be related to the dynamics of a yield fluid without the necessity of advocating the presence of water during emplacement or polydispersity of the granular material involved. The forces acting during the propagation and the arrest phase are analysed and the mechanism of formation and evolution of channelling and levees are investigated.
DE: 0545 Modeling (4255)
DE: 0560 Numerical solutions (4255)
DE: 1810 Debris flow and landslides
DE: 1815 Erosion
DE: 1824 Geomorphology: general (1625)
SC: Hydrology [H]
MN: Fall Meeting 2005