Long term volumetric evolution of an exploited sandbank. Case study on the coastal Belgian North Sea Kwintebank

Exploitation of aggregates from sandbanks off the Belgian coast has been growing over the two last decades. The authorities are now clearly facing the question of the sustainability of that activity. Ten to fifteen years of bathymetric measurements along reference tracks are available today. From those data, time series of volumes above a given reference level are computed and submitted to trend analysis techniques. The analysis indicates that the volume is decreasing (with a high level of confidence) almost everywhere. Estimated volume decrease is then compared to available exploitation data. Despite all the shortcomings of the procedure, the two quantities appear to be close to each others. Exploitation seems however not being the single component of the observed decrease.