Direct Monitoring Reveals Initiation of Turbidity Currents From Extremely Dilute River Plumes

Sophie Hage, Matthieu J.B. Cartigny, Esther J. Sumner, Michael A. Clare, John E. Hughes Clarke, Peter J. Talling, D. Gwyn Lintern, Stephen M. Simmons, Maria Azpiroz-Zabala, More Authors

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Abstract

Rivers (on land) and turbidity currents (in the ocean) are the most important sediment transport processes on Earth. Yet how rivers generate turbidity currents as they enter the coastal ocean remains poorly understood. The current paradigm, based on laboratory experiments, is that turbidity currents are triggered when river plumes exceed a threshold sediment concentration of ~1 kg/m3. Here we present direct observations of an exceptionally dilute river plume, with sediment concentrations 1 order of magnitude below this threshold (0.07 kg/m3), which generated a fast (1.5 m/s), erosive, short-lived (6 min) turbidity current. However, no turbidity current occurred during subsequent river plumes. We infer that turbidity currents are generated when fine sediment, accumulating in a tidal turbidity maximum, is released during spring tide. This means that very dilute river plumes can generate turbidity currents more frequently and in a wider range of locations than previously thought.

Original languageEnglish
Pages (from-to)11310-11320
Number of pages11
JournalGeophysical Research Letters
Volume46
Issue number20
DOIs
Publication statusPublished - 2019

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    Hage, S., Cartigny, M. J. B., Sumner, E. J., Clare, M. A., Hughes Clarke, J. E., Talling, P. J., Lintern, D. G., Simmons, S. M., Azpiroz-Zabala, M., & More Authors (2019). Direct Monitoring Reveals Initiation of Turbidity Currents From Extremely Dilute River Plumes. Geophysical Research Letters, 46(20), 11310-11320. https://doi.org/10.1029/2019GL084526