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Modelling the effect of sand extraction on the Kwinte Bank
Van den Eynde, D.; Norro, A. (2009). Modelling the effect of sand extraction on the Kwinte Bank, in: European Marine Sand and Gravel Group (EMSAGG) conference: a wave of opportunities for the marine aggregates industry, 7-8 May 2009, Rome, Italy. pp. [1-13]
In: (2009). European Marine Sand and Gravel Group (EMSAGG) conference: a wave of opportunities for the marine aggregates industry, 7-8 May 2009, Rome, Italy. European Marine Sand and Gravel Group (EMSAGG)[s.l.], meer
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Documenttype: Congresbijdrage
Trefwoorden
    Biological phenomena > Evolution
    Dredging
    Earth sciences > Geology > Geomorphology > Coastal morphology
    Models > Mathematical models
    Numerical models
    Sediment deposition
    Sedimentary structures > Bed forms > Banks (topography) > Sand banks
    Transport > Sediment transport
    Kwintebank [Marine Regions]
    Marien/Kust
Author keywords
    Sand bank; sand extraction; morphologic evolution; numerical modelling; Southern North Sea
Auteurs  Top 
  • Van den Eynde, D., meer
  • Norro, A., meer
Abstract
    In recent years, the exploitation of marine aggregates is increasing. In Belgium coastal waters, especially the Kwinte Bank is under severe pressure. During the last decade, a “depression” of 5 m developed, due to extraction of sand. Norro et al. (2003; 2006; 2009) and Norro and Ozer (2006) showed that during the period 1991-1998 the volume of the sand bank decreased significantly. In the present paper, the influence of these bathymetric changes on the sedimentation and deposition patterns are studied by numerical modelling, to obtain a first impression of the ability of the sand bank to recuperate from this sand extraction.A three-dimensional hydrodynamic model, a wave model and a local total load sediment transport model are presented, which are used to investigate the sedimentation and deposition patterns. The hydrodynamic model results are validated using ADCP current data, showing that the model gives satisfactory results, while the wave model is used for operational forecasts of the waves at the Belgian coast, thus being validated continuously. The sediment transport model results are much more subject to uncertainties but the results are in general agreement with observations.The numerical model results show that apart from the extraction of marine aggregates, the Kwinte Bank also is subject to a natural erosion of the top of the sand bank. The predicted erosion of the sand bank is of the same order of magnitude as the difference between the calculated volumetric decrease of the top of the sand bank and the estimated amount of extracted aggregates. This natural erosion of the Flemish sand banks was also found by De Moor (2002). The study therefore seems to confirm that the sand bank is not recuperating from the extraction of sand, but that by natural processes, the sand bank is further being eroded. This clearly raises the question of the sustainability with regard to the extraction of marine aggregates and suggests that the authority should define maximum exploitable quota preventing any irreversible damage.
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