HR: 11:35h
AN: H41G-06    [PDF]
TI: Can we link tectonic and geomorphic models? Some lessons to be learned from the dynamical system of a simple channel link.
AU: * Stark, C P
EM: cstark@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY 10964 United States
AB: The dynamical behavior of mountain landscapes plays a key role in the interaction between tectonics and geomorphology, and understanding this behavior is a major challenge. At the heart of the dynamics lies the spatio-temporal response of a channel network to changes in boundary conditions, such as fluctuations in climate, changes in tectonic forcing, single earthquake events, and so on. The dynamics set the rate at which a landscape converges to a steady state, if at all, and determine the response of a steady-state landscape to perturbations in the driving forces. Without a good understanding of the channel network dynamics, no reliable interpretations of spatio-temporal changes in natural landscapes can be made. By and large, most theoretical treatments of channel network and landscape dynamics (typically as landscape evolution models) have avoided treatment of the dynamical properties of channel morphology. In this exploratory study, I address the issue directly. I present a very simple model for a single channel link that encapsulates the dynamic roles that variable channel width, depth, sinuosity, bed roughness and sediment storage play in modulating the rate of sediment throughput. I focus on how the evolution of channel morphology is intimately connected to the process of bedrock channel erosion, and on how these processes determine the spatio-temporal response of a channel network and the nonlinear response of the whole landscape. Model solutions show that a single channel link can exhibit oscillatory, coupled variations in channel morphology and slope. These oscillations may decay to a stable channel slope or may reach a limit cycle where oscillations persist indefinitely, albeit over a stable range. The behavior of a coupled, double channel link model is similar. Both models predict that real mountain channels may be autocyclic, with stable oscillations in morphology and slope over the long term. They suggest that the dynamical behavior of an evolving landscape can only be modeled if the dynamics of channel morphology are taken into account.
UR: http://geomorph.ldeo.columbia.edu
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
DE: 1848 Networks
DE: 3210 Modeling
DE: 3220 Nonlinear dynamics
SC: Hydrology [H]
MN: 2003 Fall Meeting