A cohesive sediment balance for the Scheldt estuary
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This article present a method to generate a cohesive sediment balance for the Scheldt estuary (The Netherlands and Belgium). In this balance the net transports have been determined on a regional scale. The complicated circulation patterns on a smaller scale are considered as a black box.
The cohesive sediments in the balance are defined as the inorganic sediment with a particle size smaller than 63 μm. In the balance a distinction is made between the relatively ‘clean’ marine mud fraction and the more polluted fluvial fraction. The calculations are made on a basis of field data. The field data of the morphological changes in the estuary are based on the period of 1975–1985.
The net natural transport of fluvial mud is estimated to reach beyond the mouth of the estuary. The net marine import of mud is estimated to reach beyond the brackish part of the estuary, located in Belgium.
The sediment balance also provides the time scale for the response of an estuary. The time scale related to the reduction in pollution proves to be quite large. Calculations with a simple analytic model with typical values for the Scheldt estuary indicate that several decades will pass until a significant improvement in bottom sediment quality is reached even after a 100% reduction of the loading of pollutants.
The presented balance is not the final answer. Improvements can be achieved by more accurate field data, smaller morphological units and verification by other methods (cf. tracer methods, mathematical models).
Keywordsmud balance mud transport fluvial mud marine mud sediment transport sediment balance Scheldt estuary management
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- BELMANS, H., 1988. Deepening and maintenance dredging works in the Western Scheldt and Sea Scheldt. Water, 43: 184–194 (in Dutch).Google Scholar
- BIJLSMA, L. and F. STEYAERT, 1988. Bed quality development in the Western Scheldt estuary. Proc. BHRA Water modelling and measurement 2, Morrogate, UK, November 1988.Google Scholar
- DE KLERK, J., 1989. Volume calculations of the Belgian Scheldt, period 1968–1969 and period 1981–1982. Ministry of Transport. Public Works and Water Management, Directorate Zeeland, Middelburg. (in Dutch).Google Scholar
- D'HONDT, P. and T.G. JACQUES, 1982. Suspended material in the Scheldt. Evaluation of a research of the UCB for the Department of Public Health. Water, 4: 133–135 (in Dutch).Google Scholar
- GOEDHEER, G.J. 1985. Marshland development. Ministry of Transport, Public Works and Water Management. Tidal Waters Division, Middelburg, Report DDMI-85.22 (in Dutch).Google Scholar
- LAANE, R.W.P.M., E. TURKSTRA and W. G. MOOK, 1990. Stable carbon isotope composition of pelagic and benthic organic matter in the North Sea and adjacent estuaries. In: Facets of modern biogeochemistry, Festchrift for E. T. Degens. Springer, Berlin p. 214–224.Google Scholar
- MULDER, H.P.J. and C. UDINK, 1991. Modelling of cohesive sediment transport; A case study: the Western Scheldt estuary. In: B.L. Edge. Ed., 22nd Coastal Engin. Conf., Proc. Internat. Conf. Delft, The Netherlands, p. 3012–3023.Google Scholar
- SALOMONS, W., W.D. EYSINK and H.N. KERDIJK, 1981. Inventory and geochemical behaviour of heavy metals in the Scheldt and the Western Scheldt. Report M1640/M1736, Delft Hydraulics (in Dutch).Google Scholar
- SALOMONS, W. and W.D. EYSINK, 1981. Pathways of mud and particulate trace metals from rivers to the southern North Sea. In: S.D. Nio, R.T.E. Schüttenhelm and T.C.E. Van Weering Eds., Holocene Marine Sedimentation in the North Sea Basin, p. 429–450.Google Scholar
- VAN DEN BERG, J.H., D. SCHOUTEN and C.J. VAN WESTENBRUGGE, 1991. Sand balance Western Scheldt 1965–1970–1975–1980–1985, Report NWL-91.36, Ministry of Transport, Public Works and Water Management, Directorate Zeeland, Middelburg (in Dutch).Google Scholar
- VAN ECK, G.Th.M. and N.M. DE ROOIJ, 1990. Development of a water quality and bio-accumulation model for the Scheldt estuary. In: Michaelis, Ed., Coastal and Estuarine Studies, Estuarine Water Quality Management, Springer, Berlin, p. 95–194.Google Scholar
- WOLLAST, R. and J.J. PETERS, 1983. Transfer of materials in estuarine zones. In: J.B. Pearce, Ed., Review of water quality and transport of mateirals in coastal and estuarine waters, ICES Copenhagen, p. 200–216.Google Scholar