HR: 13:55h
AN: H43H-02 INVITED    [Abstracts]
TI: Hillslope processes and the delivery of sediment to the channel
AU: * Heimsath, A M
EM: Arjun.Heimsath@ASU.edu
AF: School of Earth and Space Sciences, Arizona State University, Tempe, AZ 85287, United States
AB: There are several classic "chicken-egg" problems yet to be resolved in our pursuit of understanding how landscapes evolve. Here we focus on the problem of hillslope coupling with channels. As articulated by the conveners, a principal question is whether hillslopes are equal partners with channels in regulating landscape adjustment rates? Or, is there an imbalance such that either channel incision is driving hillslope evolution, or that sediment delivery from the surrounding hillslopes is setting channel incision? Naturally, there are many variables to control for, such as climate, tectonics and lithology, when trying to answer any of these questions. We try to constrain the numerous scenarios and special cases of landscape evolution by focusing on three classic characteristic profiles that can represent most landscapes. First, the equilibrium profile where, to the best of our knowledge, channels and hillslopes are eroding at roughly the same rate. Second, the inner-gorge profile, where we believe the channels are outpacing significantly the hillslopes. Lastly, the flattening landscape where the hillslopes are thought to be wearing down more rapidly than the channels are incising. Examples of each of these characteristic profiles are found under a wide range of climatic and tectonic settings, although they are more commonly used to typify specific conditions. We present data quantifying hillslope sediment delivery processes and rates from several field-based methodologies: cosmogenic nuclides for erosion rates, major and trace elements for chemical weathering, short-lived isotopes and optically stimulated luminescence analyses for sediment transport processes, and morphometry to define the characteristic form of the landscape. We use these data to propose an approach towards determining the dominance of hillslope or channel.
DE: 1625 Geomorphology and weathering (0790, 1824, 1825, 1826, 1886)
DE: 1804 Catchment
DE: 1825 Geomorphology: fluvial (1625)
DE: 1826 Geomorphology: hillslope (1625)
DE: 1862 Sediment transport (4558)
SC: Hydrology [H]
MN: 2007 Fall Meeting