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 E.; 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

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.m‐3. Here we present direct observations of an exceptionally dilute river‐plume, with sediment concentrations one order of magnitude below this threshold (0.07 kg.m‐3), which generated a fast (1.5 m.s‐1), 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., Sumner, E. J., Clare, M. A., Hughes Clarke, J. E., 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: Oct 10, 2019
• Publicly Available Date: Nov 4, 2019
• Journal: Geophysical Research Letters
• Print ISSN: 0094-8276
• Electronic ISSN: 1944-8007
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 46
• Issue: 20
• Pages: 11310-11320
• DOI: https://doi.org/10.1029/2019gl084526
• Public URL: https://durham-repository.worktribe.com/output/1283261