Direct Monitoring Reveals Initiation of Turbidity Currents From Extremely Dilute River Plumes
Sophie Hage (National Oceanography Center, University of Southampton)
Matthieu J.B. Cartigny (Durham University)
Esther J. Sumner (University of Southampton)
Michael A. Clare (National Oceanography Center)
John E. Hughes Clarke (University of New Hampshire Durham)
Peter J. Talling (Durham University)
D. Gwyn Lintern (Geological Survey of Canada Sidney)
Stephen M. Simmons (University of Hull)
Maria Azpiroz-Zabala (TU Delft - Applied Geology)
undefined More Authors (External organisation)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
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.
help_outline