HR: 10:20h
AN: T12D-01    [Abstracts]
TI: Orogenic Plateaux Produce Sigmoidal River Profiles
AU: * Saville, C
EM: christopher.saville@durham.ac.uk
AF: Durham University, Department of Earth Sciences, Durham University, Durham, DH1 3LE, United Kingdom
AU: Allen, M B
EM: m.b.allen@durham.ac.uk
AF: Durham University, Department of Earth Sciences, Durham University, Durham, DH1 3LE, United Kingdom
AU: Jones, S J
EM: stuart.jones@durham.ac.uk
AF: Durham University, Department of Earth Sciences, Durham University, Durham, DH1 3LE, United Kingdom
AB: Rivers draining an orogen control the transport of sediment through it. A tenet of fluvial geomorphology is that a river's longitudinal profile evolves towards a graded, concave-up form. Curvature analysis of river long profiles, using satellite images and SRTM data, shows this to be incorrect for the major rivers draining the Tibetan and Turkish-Iranian plateaux. Instead, both plateaux show long wavelength (>100 km) convexities in rivers on a regional scale. These convexities cause the rivers to have sigmoidal long profiles, with low gradient reaches at high elevations. We suggest that the control on the convex-up reaches is the combination of the lack of active thrusting and aridity in the plateau interior. Both factors result in low levels of incision at high elevation. Simple numerical modelling shows variation in incision along the length of a river can produce profiles that are similar to those observed. Limited incision within a plateau interior suggests a lower sediment flux from orogenic plateaux than if a graded profile were attained.
DE: 1819 Geographic Information Systems (GIS)
DE: 1825 Geomorphology: fluvial (1625)
DE: 8169 Sedimentary basin processes
DE: 8175 Tectonics and landscape evolution
DE: 9320 Asia
SC: Tectonophysics [T]
MN: 2007 Fall Meeting