Wave- and current-induced bottom shear stress distribution in the Gulf of Lions

Type Article
Date 2008-08
Language English
Author(s) Dufois Francois1, 2, 3, Garreau PierreORCID1, Le Hir Pierre1, Forget P3
Affiliation(s) 1 : IFREMER, DYNECO PHYSED, Ctr Brest, F-29280 Plouzane, France.
2 : Ctr Ifremer, IRSN, LERCM, DEI SESURE, F-83507 La Seyne Sur Mer, France.
3 : CNRS USTV, UMR 6017, LSEET LEPI, F-83957 La Garde, France.
Source Continental Shelf Research (0278-4343) (Elsevier), 2008-08 , Vol. 28 , N. 15 , P. 1920-1934
DOI 10.1016/j.csr.2008.03.028
WOS© Times Cited 36
Keyword(s) Gulf of Lions, 3D modelling, Bottom shear stress, Sediment transport
Abstract Simulations of both currents and waves were performed throughout the year 2001 to assess the relative contribution of each to their overall erosive potential on the Gulf of Lions shelf. Statistical analysis of bottom shear stress (BSS) was compared to sediment grain-size distribution on the bottom. The hydrodynamic features of the bottom layer coincide with the distribution of surficial sediments, and three areas with different hydro-sedimentary characteristics were revealed. (i) The sandy inner shelf ( < 30 m) area is a high-energy-wave dominated area but may be subjected to intense current-induced BSS during on-shore winds along the coast and during continental winds mainly in the up-welling cells. (ii) The middle shelf (30-100 m) is a low-energy environment characterised by deposition of cohesive sediments, where the wave effect decreases with depth and current-induced BSS cannot reach the critical value for erosion of fine-grained sediments. (iii) The outer shelf, which has a higher bottom sand fraction than the middle shelf, may be affected by strong south-westward currents generated by on-shore winds, which can have an erosive effect on the fine-grained sediments. Particular attention was paid to features of the current that were found to be predominant on the mid-outer shelf. These currents are strongly dependent on wind direction. (C) 2008 Elsevier Ltd. All rights reserved.
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