Direct monitoring reveals initiation of turbidity currents from extremely dilute river plumes

Hage, Sophie; Cartigny, Matthieu J B; Sumner, Esther J; Clare, Michael A; Hughes Clarke, John; Talling, Peter J; Lintern, D. Gwyn; Simmons, Stephen M; Silva Jacinto, Ricardo; Vellinga, Age J; Allin, Joshua R; Azpiroz-Zabala, Maria; Gales, Jenny A; Hizzett, Jamie L; Hunt, James E; Mozzato, Alessandro; Parsons, Daniel R.; Pope, Ed L; Stacey, Cooper D; Symons, William O; Vardy, Mark E; Watts, Camilla

Abstract

©2019. The Authors. 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.

Citation

Hage, S., Cartigny, M. J. B., Sumner, E. J., Clare, M. A., Hughes Clarke, J., Talling, P. J., Lintern, D. G., Simmons, S. M., Silva Jacinto, R., Vellinga, A. J., Allin, J. R., Azpiroz-Zabala, M., Gales, J. A., Hizzett, J. L., Hunt, J. E., Mozzato, A., Parsons, D. R., Pope, E. L., Stacey, C. D., Symons, W. O., …Watts, C. (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

• Journal Article Type: Article
• Acceptance Date: Sep 2, 2019
• Online Publication Date: Sep 13, 2019
• Publication Date: Oct 28, 2019
• Deposit Date: Nov 18, 2019
• Publicly Available Date: Mar 14, 2020
• Journal: Geophysical Research Letters
• Print ISSN: 0094-8276
• Publisher: American Geophysical Union
• Peer Reviewed: Peer Reviewed
• Volume: 46
• Issue: 20
• Pages: 11310-11320
• DOI: https://doi.org/10.1029/2019gl084526
• Public URL: https://hull-repository.worktribe.com/output/2666623
• Publisher URL: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL084526
• Related Public URLs: http://dro.dur.ac.uk/29276/; https://eprints.soton.ac.uk/434754/
• Additional Information: Received: 2019-07-16; Accepted: 2019-09-02; Published: 2019-10-29
• Contract Date: Nov 18, 2019