Morphodynamique et géométrie des rivières, turbidites et formes de lit

Morphodynamics and geometry of channels, turbidites, and bedforms

• Auteur / Autrice : Aymeric-Pierre Peyret
• Direction : François Métivier, David Mohrig
• Type : Thèse de doctorat
• Discipline(s) : Géophysique. Dynamique des fluides géologiques. Dynamique des reliefs et paysages
• Date : Soutenance en 2011
• Etablissement(s) : Institut de physique du globe (Paris ; 1921-....) en cotutelle avec University of Texas (Austin, Texas) (1881-....)

Mots clés

Mots clés contrôlés

Turbidites

Cours d'eau

Mots clés libres

Morphodynamisme

Résumé

The evolution of landscapes and seascapes in time is the result of the constant interaction between flows and topography. Flows change topography, which in turn change the flow. This feedback causes evolution processes to be highly non-linear and complex. When full analytical derivations of the co-evolution of topography and flow are not possible without oversimplifications, as is the case in river bends, recent large topographical datasets and modern computers allow for correlations between horizontal (planview) and cross-sectional geometry of channels. Numerical analysis in the Mississippi and Trinity rivers indicate that the type of correlation between river radius of curvature and bankfull channel width depends on the migration behavior of the river. In other cases, channel topography may only have a second-order effect on its own evolution, as is the case for fully depositional turbidity currents, and the evolution of æolian field topography may only be a function of this topography. I show that in these situations, changes in topography may be decoupled from details of the flow field and modeled very easily with a good accuracy.