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

TitleDirect Monitoring Reveals Initiation of Turbidity Currents From Extremely Dilute River Plumes
Publication TypeJournal Article
Year2019
AuthorsHage, S, Cartigny, MJB, Sumner, E, Clare, MA, Hughes Clarke, JE, Talling, PJ, Lintern, G, Simmons, S, Jacinto, R, Vellinga, A, Allin, J, Azpiroz-Zabala, M, Gales, J, Hizzett, J, Hunt, J, Mozzato, A, Parsons, D, Pope, E, Stacey, CD, Symons, W, Vardy, M, C., W
JournalGeophysical Research Letters
Volume46(20)
Pages11310-11320
Date Published28 October

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.

Publication Linkhttps://doi.org/10.1029/2019GL084526
Refereed DesignationRefereed
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