Direct monitoring reveals initiation of turbidity currents from extremely dilute river plumes
|Author(s)||Hage Sophie1, 2, Cartigny Matthieu J.B.3, Sumner Esther J.2, Clare Michael A.1, Hughes Clarke John E.4, Talling Peter J.3, Lintern D. Gwyn5, Simmons Stephen M.6, Silva Jacinto Ricardo7, Vellinga Age J.2, Allin Joshua R.8, Azpiroz‐zabala Maria9, Gales Jenny A.10, Hizzett Jamie L.2, Hunt James E.1, Mozzato Alessandro2, Parsons Daniel R.6, Pope Ed L.3, Stacey Cooper D.5, Symons William O.11, Vardy Mark E.1, Watts Camilla2|
|Affiliation(s)||1 : National Oceanography Centre Southampton European Way Southampton ,U.K.
2 : School of Ocean and Earth Sciences, University of Southampton European Way Southampton, U.K.
3 : Department of GeographyDurham University South,U.K.
4 : Center for Coastal and Ocean Mapping, University of New Hampshire Durham NH ,USA
5 : Natural Resources Canada, Geological Survey of Canada Sidney BC ,Canada
6 : Energy and Environment Institute, University of Hull ,U.K.
7 : Marine Geosciences Unit, IFREMER, Centre de Brest Plouzané, France
8 : Geotek Ltd, 4 Sopwith Way Daventry, UK
9 : Faculty of Civil Engineering and Geosciences, 2628 CN Delft University, The Netherlands
10 : School of Biological and Marine Sciences, Drake Circus, University of Plymouth, PL48AA, U.K.
11 : CGG Robertson Llandudno North Wales ,UK
|Source||Geophysical Research Letters (0094-8276) (American Geophysical Union (AGU)), 2019-10 , Vol. 46 , N. 20 , P. 11310-11320|
|WOS© Times Cited||58|
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.