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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : Estuaries, tidal inlets, escoffier, o,brien and morphological attractors
Estuaries, tidal inlets, escoffier, o,brien and morphological attractors
Author : J.B. HINWOOD(1) AND E.J. MCLEAN(2)
per the authors showed that over very long time scales a barrier estuary or tidal inlet will tend towards
one of two states, called attractors. In this paper it is shown how that analysis represents an extension and
generalisation of three earlier analyses. The class of estuaries we consider is the barrier estuary in which a tidal basin is
connected to the sea by a constricted entrance channel through an erodable sand barrier. In such estuaries, tidal
exchange is the dominant process controlling water and sediment transports. The entrance channel through the barrier
provides a significant hydrodynamic resistance and has a regulating effect on the tidal prism. The three widely
recognised quantitative “laws” describing the long term equilibrium dimensions of the entrance channel are: the tidal
prism-entrance area relations, often referred to as the O'Brien equation, secondly the Escoffier or closure diagram,
based on a simple hydrodynamic relationship between the entrance area and the entrance velocity plus an empirical
"equilibrium velocity", and thirdly the Bruun rule relating the entrance channel stability to the longshore sediment supply.
Each of these is based on major simplifications that restrict its utility and range of validity more than is usually
The attractor analysis, while still based on a lumped model, adds sediment transport and deposition/scour equations and
enables the use of more realistic entrance hydrodynamics. It predicts the rates of change and presents the results on a
practical “attractor map”. The predictions of the three laws are shown on the attractor map and their practical application
is critically compared.Form Required :
File Size : 842,549 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 20/08/2015
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