Environmental controls on the spatial variation in sand wave morphology and dynamics on continental shelves

Geoscience Seminar, Speaker Thaiënne A.G.P. van Dijk, Dept. of Applied Geology and Geophysics, Deltares, Netherlands

"Environmental controls on the spatial variation in sand wave morphology and dynamics on continental shelves"

Thaiënne A.G.P. van Dijk, Dept. of Applied Geology and Geophysics, Deltares, Netherlands & Dept. of Geology, University of Illinois, USA

Large-scaled sea-bed dynamics of the Netherland Continental Shelf revealed that, offshore, sand waves are the most dynamic bedforms on scales that could be investigated from multibeam time series. Sand wave morphology and dynamics on continental shelves vary spatially, depending on bed properties and hydrodynamic characteristics, and may interfere with navigation and offshore engineering. Understanding the morphodynamics of sand waves may allow for better predictions of bed levels and therewith the optimisation of risk-based monitoring policies, maintenance strategies of fairways and designs of offshore constructions, such as offshore wind farms.

To date, empirical researches into sand wave morphodynamics comprise mostly local studies. However, for the explanation of the spatial variation on continental shelves, a large-scaled investigation is required. Here, the quantified morphologies of all sand waves on the Netherlands Continental Shelf (NCS) at grid resolution are presented. Correlations to primary local parameters as well as to processes of sediment transport show that the mode of sediment transport (bed load versus suspended) may be the controlling process. Although not as quantitative to date, similar investigations for sand wave migration rates, which on the NCS range between 0 and 20 m/yr, may also lead to hypothesised controls on the behaviour of sand waves on continental shelves.

A brief introduction to the institute Deltares, Netherlands, will be given to start with.

Thaiënne van Dijk Seminar