Tidally-induced shear stress variability above intertidal mudflats in the macrotidal Seine estuary

Type Article
Date 2006-08
Language English
Author(s) Verney RomaricORCID1, 2, Brun Cottan J3, Lafite R1, Deloffre J1, Taylor J4
Affiliation(s) 1 : Univ Rouen, UMR Morphodynam Continentale & Cotiere 6143, CNRS, F-76821 Mont St Aignan, France.
2 : IFREMER, DYNECO PHYSED, F-29280 Plouzane, France.
3 : Univ Caen, UMR Morphodynam Continentale & Cotiere 6143, CNRS, F-14000 Caen, France.
4 : Univ Sussex, Sch Life Sci, Coastal & Estuarine Res Grp, Brighton BN1 9QJ, E Sussex, England.
Source Estuaries and coasts (1559-2723) (Estuarine Research Federation), 2006-08 , Vol. 29 , N. 4 , P. 653-664
WOS© Times Cited 25
Keyword(s) Seine estuary (France), Spatial variability, Neap spring conditions, Intertidal mudflat, Shear stress, Tidal currents
Abstract Tidal currents and the spatial variability of tidally-induced shear stress were studied during a tidal cycle on four intertidal mudflats from the fluvial to the marine part of the Seine estuary. Measurements were carried out during low water discharge (< 400 m(3) s(-1)) in neap and spring tide conditions. Turbulent kinetic energy, covariance, and logarithmic profile methods were used and compared for the determination of shear stress. The c(TKE) coefficient value of 0.19 cited in the literature was confirmed. Shear stress values were shown to decrease above mudflats from the mouth to the fluivial part of the estuary due to dissipation of the tidal energy, from 1 to 0.2 N m-(2) for spring tides and 0.8 to 0.05 N m(-2) for neap tides. Flood currents dominate tidally-induced shear stress in the marine and lower fluvial estuary during neap and spring tides and in the upper fluvial part during spring tides. Ebb currents control tidally-induced shear stress in the upper fluvial part of the estuary during neap tides. These results revealed a linear relationship between friction velocities and current velocities. Bed roughness length values were calculated from the empirical relationship given by Mitchener and Torfs (1996) for each site; these values are in agreement with the modes of the sediment particle-size distribution. The influence of tidal currents on the mudflat dynamics of the Seine estuary was examined by comparing the tidally-induced bed shear stress and the critical erosion shear stress estimated from bed sediment properties. Bed sediment resuspension induced by tidal currents was shown to occur only in the lower part of the estuary.
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Verney Romaric, Brun Cottan J, Lafite R, Deloffre J, Taylor J (2006). Tidally-induced shear stress variability above intertidal mudflats in the macrotidal Seine estuary. Estuaries and coasts, 29(4), 653-664. Open Access version : https://archimer.ifremer.fr/doc/00000/1887/