A bi-dimensional approach to assessing the volumetric evolution of an exploited sandbank

We analyse the multi-annual evolution of bathymetry along several cross-sections of the Kwintebank (one of the Flemish Banks). An important issue in the area is the intensive exploitation under regulations imposed by the Belgian authorities that aim to guarantee sustainability of extractions. All bathymetric data collected during the period 1987-2000 at a frequency of approximately four surveys per year are analysed, to identify volumetric temporal trends. The errors inherent in the measurements taken with a single-beam instrument are examined. The lack of indisputable quality criteria led to the choice of robust statistical methods. A statistically significant annual decline of approximately 1.5% in bank volume is shown. Another practical conclusion is that a big increase in sampling frequency is necessary if the authorities set a criterion regarding the long-term sustainability of the bank and wish to have a swift guarantee that this criterion is being observed. (c) 2005 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved