HR: 17:30h
AN: H44B-07    [Abstracts]
TI: Controls on channel width in large rivers dissecting the eastern margin of the Tibetan Plateau
AU: * Ouimet, W
EM: wouimet@mit.edu
AF: Penn State University, Department of Geosciences, University Park, PA 16802,
AU: Kirby, E
EM: ekirby@geosc.psu.edu
AF: Penn State University, Department of Geosciences, University Park, PA 16802,
AU: Whipple, K
EM: kxw@asu.edu
AF: Arizona State University, School of Earth and Space Exploration, Tempe, AZ 85287,
AB: The eastern margin of the Tibetan plateau is characterized by large rivers dissecting regionally-elevated topography that has developed in association with the continued convergence of the Indian subcontinent and Eurasia. Here, we present an extensive dataset of channel width collected from field surveys along the region's largest rivers. These data allow us to more fully characterize channel morphology during transient landscape evolution and provide insight into the manner in which channels adjust to tectonic and lithologic variability. We combine our width data with detailed analysis of river profiles, channel gradients and direct measures of erosion and incision rates. Data reveal that rivers dynamically adjust gradient and width in response to spatial variations in uplift, erosion and rock erodibility. Width trends from rivers experiencing downstream increases in erosion rate indicate channel narrowing (W~A^0.1-0.3), relative to typical scaling of width with increasing drainage area (W~A^0.4-0.5). Width trends from rivers experiencing downstream decreases in erosion rate, meanwhile, indicate channel widening (W~A^0.6), relative to the typical scaling. Superimposed on these general width trends are systematic variations in channel width and gradients of large rivers that reflect local differences in bedrock lithology and channel morphology, the influence of large landslides, and local non- uniform uplift related to active faults.
DE: 1815 Erosion
DE: 1825 Geomorphology: fluvial (1625)
DE: 1856 River channels (0483, 0744)
DE: 8175 Tectonics and landscape evolution
DE: 9320 Asia
SC: Hydrology [H]
MN: 2007 Fall Meeting