Details

The Netherlands Hydrographic Office has requested Deltares to validate their re-survey policy for the Netherlands Continental Shelf based on scientific methods. Controlling parameters in the validation are the natural morphodynamics of the North Sea bed and the grounding risks of shipping. Deltares developed an objective method to analyse the seabed morphodynamics from time series of echo sounding data. The quantification of the vertical nodal dynamics of the Netherlands Continental Shelf (on a 25 x 25 m resolution) reveals that regions with rhythmic bedforms are particularly dynamic. Detailed analyses of these dynamic zones provide the growth and migration of individual bedforms. In almost the entire Southern Bight, observed average migration rates are 0 to 5 m/yr, except near Texel, where average migration rates are up to 19 m/yr. The University of Twente performed sand wave modelling to explain the potential impact of environmental conditions on the shape and dynamics of sand waves. In collaboration with MARIN, grounding danger was quantified for the Netherlands Continental Shelf (1 x 1 km resolution). Both the morphodynamics and grounding danger were used in an overlay to validate and optimise the existing re-survey policy of the Netherlands Hydrographic Office.