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Tidal characteristics of an accretional tidal flat (The Wash, U.K.)
Ke, X.; Collins, M. (2000). Tidal characteristics of an accretional tidal flat (The Wash, U.K.), in: Flemming, B.W. et al. (Ed.) Muddy coast dynamics and resource management. Proceedings in Marine Science, 2: pp. 13-38
In: Flemming, B.W.; Delafontaine, M.T.; Liebezeit, G. (Ed.) (2000). Muddy coast dynamics and resource management. Proceedings in Marine Science, 2. Elsevier: Amsterdam. ISBN 0-444-50464-8. 294 pp., more
In: Proceedings in Marine Science. Elsevier: New York. ISSN 1568-2692, more
Peer reviewed article  

Available in  Authors 
    VLIZ: Dynamical Oceanography [6339]

Keyword
    Marine

Authors  Top 
  • Ke, X.
  • Collins, M.

Abstract
    Tidal current velocities and water depths have been surveyed repeatedly across an intertidal flat/saltmarsh in a rectangular coastal embayment (The Wash) over three consecutive years to study the tidal hydrodynamics. The tide in the bay has a standing wave character. In response to the changing elevations, the standing tidal wave over the tidal flat is shown to normally be associated with tidal current velocity maxima (i) at mid tide at/below mean low water, and (ii) at or shortly after the end of the ebb and beginning of the flood at/above mid-tide level. Tidal asymmetry is prominent, the ratio between the duration of the flood and ebb phases being 0.65-1.0. This indicates that the flood tidal flows are generally of shorter duration and of higher current velocities. The tidal currents have different velocities in the offshore channels (ca. 1.2 m S-¹), over the exposed intertidal flats (ca. 0.5-0.7 m S-¹), and in the saltmarshes (<0.2 m s-¹). There are abrupt changes in velocities at the various sedimentary/geomorphological boundaries where steep gradients exist. The hydrodynamic situation is characterised by flood dominance, being important in controlling water and sediment advection as well as sedimentation in this tide-dominated environment. Based on the tidal current velocities, seabed sediment grain size, and the Sundborg (1967) sediment transport model, the sediments on the intertidal flats were found to be transported in suspension for 63% of the duration of a tidal cycle, there being an absence of any prolonged transport for the remaining 37%. Over the saltmarshes, sediments were transported in suspension only, the observed net deposition of the suspended load corroborating the long-term accretional nature of the study area. Bedload transport was not observed at any tidal stage.

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