HR: 1340h
AN: H43D-0525    [Abstracts]
TI: Typhoons, Extreme Discharge, and Bedrock River Meanders: a Quantitative Relationship Between Regional Climatology and DEM-Derived Sinuosity
AU: * Barbour, J R
EM: jbarbour@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AU: Stark, C P
EM: cstark@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AB: It is notoriously difficult to extract from landscapes any quantitatively meaningful signatures of climate or tectonics. While some topographic studies have been able to infer basic tectonic boundary conditions, they have shown little success so far in inferring the values of key climatic variables that shape the relief. We set ourselves the challenge of doing just that, and we chose as our focus the sinuosity of mountain rivers as measured using the SRTM digital elevation model. Bedrock rivers adopt a sinuous, sometimes meandering form, just as do alluvial rivers, and this sinuosity is achieved through both lateral and vertical erosion. Measurement of DEM-derived mountain river sinuosity, together with analysis of discharge statistics, could therefore provide constraints on channel incision processes. Our analysis of mountain catchments across the western North Pacific cyclone basin has revealed that sinuosity is not controlled by mean flow conditions. Rather, for geologically similar terrain, sinuosity appears to relate directly to the shape of the discharge distribution. Rivers that have more relative variance in discharge tend to have greater lateral mobility. Discharge variability is a function of rainfall variability, which is dominated in our study area by the climatology of tropical cyclones. We conclude that mountain river sinuosity in the western North Pacific is controlled by typhoon strike frequency.
DE: 1807 Climate impacts
DE: 1815 Erosion
DE: 1825 Geomorphology: fluvial (1625)
SC: Hydrology [H]
MN: Fall Meeting 2005