Improving a bathymetric resurvey policy with observed sea floor dynamics

Abstract

Bathymetric resurveying in shallow seas is a costly process with limited resources, yet necessary for adequate nautical charts and therefore crucial for safe navigation. An important factor in an efficient resurvey policy is the type and size of sea floor dynamics. We propose four indicators, which we use in a procedure to recommend changes to the resurvey policies of the Belgian and Netherlands Continental Shelf (BNLCS). These shallow regions are characterised by a sandy sea floor covered with rhythmic patterns. The proposed indicators follow from the estimates for sea floor dynamics, as given by applying the statistical method of deformation analysis. We present a concept for the shallowest likely depth surface, on which we base two of the indicators. The other two indicators may act as a warning: they quantify the potentially missed dynamics, which makes the procedure more robust in case of complicated morphology. Finally, applying our procedure to the BNLCS, we show clear differences in recommended resurvey priority between the five analysed regions, which currently have equal resurvey frequencies.