Subsurface sediment properties and potential impacts of marine sand extraction on sand wave occurrence on the Netherlands Continental Shelf

Bedform existence in shallow shelf seas is predominantly controlled by the surface sediment characteristics. However, the sediment characteristics might change following sediment extraction, as this exposes a currently burried layer. This study presents a method to use existing sediment data to map the median grain size and mud content in the current surface layer and the deeper layer, to quantify the change between the layers and to analyse how this change might affect sand wave occurrence. When applied to the Netherlands Continental Shelf, this reveals that, on average, the deeper layer contains finer (230 versus 219 μm) and muddier (1.7 versus 1.3%), although local variations can be considerable. Furthermore, our results suggest that the potential exposure of the deeper layer might reduce the sand wave area by 300 km².