Morphological stability of inlets and tidal channels in the western Wadden Sea
Gerritsen, F. (1992). Morphological stability of inlets and tidal channels in the western Wadden Sea, in: Dankers, N.M.J.A. et al. (Ed.) Present and Future Conservation of the Wadden Sea: Proceedings of the 7th International Wadden Sea Symposium, Ameland 1990. Publication Series. Netherlands Institute for Sea Research (NIOZ), 20: pp. 151-160
In: Dankers, N.M.J.A.; Smit, C.J.; Scholl, M. (Ed.) (1992). Present and future conservation of the Wadden Sea: Proceedings of the 7th International Wadden Sea Symposium, Ameland 1990. Publication Series. Netherlands Institute for Sea Research (NIOZ), 20. Netherlands Institute for Sea Research (NIOZ): Texel. VIII, 301 pp., meer
In: Publication Series. Netherlands Institute for Sea Research (NIOZ). NIOZ: Den Burg. ISSN 0923-330X, meer
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Documenttype: Congresbijdrage
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| Abstract |
In this report morphological stability of the inlets in the western Wadden Sea is considered, together with the stability conditions of the tidal channels of the flood tidal delta of the Vlie inlet. For the gorge sections of the inlets, cross-sectional stability is the main concern, for which morphological empirical relationships can be established relating the cross-section to characteristic flow parameters. In this paper we have used flood volume, ebb volume or tidal prism as a characteristic parameter. The empirical relationships between cross-section and tidal prism are affected by the mean depth of the channel. From a relationship between the tide averaged velocity (over flood and ebb period) and the hydraulic radius of a channel, a relationship is established between the cross-sectional area and the tidal prism, in which the depth (or width) of the channel acts as an additional parameter. The dimensionless stability shear stress is a new concept, and its use seems to be promising in future analysis. An advantage of the use of the stability shear stress, is that the effects of wave action and littoral drift can be evaluated for each particular case. In order to predict the behaviour of the Wadden area as a response to external changes, morphodynamic models need to be developed. The combination of a hydraulic numerical model, such as WAQUA, with a consistent set of empirical morphological relationships, built into the model, is at present seen to provide the best tool for the predicting of morphological developments. A case of special significance is the response to a faster rising sealevel of the Wadden Sea and its inlets and adjacent coasts. |
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