HR: 0800h
AN: H51A-1110    [Abstracts]
TI: Rapid response of a large river system to climate change, and its efficient downstream transfer of the signal: How is such close coupling of source to sink achieved?
AU: * Goodbred, S L
EM: steven.goodbred@sunysb.edu
AF: Stony Brook University, Marine Sciences Research Center, Stony Brook, NY 11794-5000 United States
AB: It is generally held that the response-time of fluvial systems to climate change and the resulting flux of material to the continental margin vary significantly with basin size, such that large systems respond slowly and that signals are sharply attenuated downstream. Timescales typically discussed for basinwide fluvial responses to climate change are on the order of 10$^{5}$-10$^{7}$ years. However, reconstructions of the Ganges dispersal system through the late Quaternary reveal basinwide responses to summer monsoon strength, with sediment flux at the margin varying an order of magnitude over periods of a few millennia. This raises the question of how a massive basin like the Ganges can vary so significantly at relatively short timescales. The paper presented here discusses numerous factors involved in this response pattern, including both regional and local-scale aspects. It is suggested that influences at both scales are critical for generating the rapid, basinwide responses described for the Ganges system. Of course regional influences are necessary to generate broad-scale, large-magnitude responses, but because these forcings are imparted over a diverse geological setting (mountain to marine), local factors play a key role in linking these distinct reaches of the dispersal system. Identifying the most important of such factors, and testing them via numerical models, will be important for recognizing similar response histories in other modern and ancient dispersal systems. It is suggested here that, in general, highly seasonal sub-tropical disperal systems are the most likely to show a strong sensitivity and basin-scale response to climate change.
DE: 3022 Marine sediments--processes and transport
DE: 1815 Erosion and sedimentation
DE: 1223 Ocean/Earth/atmosphere interactions (3339)
DE: 1625 Geomorphology and weathering (1824, 1886)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting