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

Hage, S. et al. (2019) Direct monitoring reveals initiation of turbidity currents from extremely dilute river plumes. Geophysical Research Letters, 46(20), pp. 11310-11320. (doi: 10.1029/2019gl084526) (PMID:31894170) (PMCID:PMC6919390)

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.

• Item Type: Articles
• Additional Information: The field campaign was supported by Natural Environment Research Council Grants NE/M007138/1 and NE/M017540/1. S.H. was funded by the National Oceanography Centre (UK) and ExxonMobil. M. J. B. C. was funded by a Royal Society Research Fellowship. M.A. C. was supported by the U.K. National Capability NERC CLASS program (NERC Grant NE/R015953/1)and NERC Grants (NE/P009190/1 and NE/P005780/1). D. R. P. acknowledges funding received from the European Research Council under the European Union's Horizon 2020 research and innovation program (Grant Agreement725955). E. L. P. was supported by a Leverhulme Trust Early Career Fellowship (ECF‐2018‐267).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Bompard, Dr Millie
• Authors: Hage, S., Cartigny, M. J. B., Sumner, E. J., Clare, M. A., Hughes Clarke, J. E., Talling, P. J., Gwyn Lintern, D., 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., Vardy, M. E., and Watts, C.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Geophysical Research Letters
• Publisher: Wiley
• ISSN: 0094-8276
• ISSN (Online): 1944-8007
• Published Online: 13 September 2019
• Copyright Holders: Copyright © 2019 The Authors
• First Published: First published in Geophysical Research Letters 46(20):11310-11320
• Publisher Policy: Reproduced under a Creative Commons license