Hyperpycnal river flows from an active mountain belt

Dadson, S. and Hovius, N. and Pegg, S. and Dade, W. B. and Horng, M. J. and Chen, H. (2005) Hyperpycnal river flows from an active mountain belt. Journal of Geophysical Research: Earth Surface, 110 (F4). DOI 10.1029/2004JF000244

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Abstract

Rivers draining the tectonically active island of Taiwan commonly discharge suspended sediment to the ocean at hyperpycnal concentrations (>40 kg m−3), typically during typhoon-driven floods. During the period 1970–1999, between 99 and 115 Mt yr−1 of sediment was discharged at hyperpycnal sediment concentrations from Taiwan to the sea. This amount represents 30–42% of the total sediment discharge from Taiwan to the ocean. The spatial distribution of hyperpycnal discharge broadly mirrors the pattern of total sediment discharge, and rivers draining catchments having recent earthquakes and weak rocks, such as the Choshui and Erhjen, discharge up to 50–70% of their sediment at hyperpycnal concentrations. Following the Chi-Chi earthquake, the frequency of hyperpycnal flows increased, because of an earthquake-driven increase in sediment supply. Landslides triggered by the Chi-Chi earthquake have resulted in an increase in the concentration of suspended sediment in rivers for a given water discharge. In turn, the threshold flood discharge required to generate hyperpycnal flow has decreased, and so hyperpycnal flows are occurring more frequently. Our findings suggest that if hyperpycnal plumes evolve into bottom-hugging gravity currents descending to and ultimately debouching in the deep sea, earthquakes may be recorded as bundles of turbidites.

Item Type: Article
Additional Information: F04016
Uncontrolled Keywords: 2006 AREP 2005 P IA50
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Journal of Geophysical Research: Earth Surface
Volume: 110
Identification Number: 10.1029/2004JF000244
Depositing User: Sarah Humbert
Date Deposited: 09 Jun 2011 12:04
Last Modified: 23 Jul 2013 09:58
URI: http://eprints.esc.cam.ac.uk/id/eprint/1614

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