Comparison between predicted and observed large-scale sea bed features in the Southern North Sea

The bottom of the Southern North Sea is partly covered by tidal sand banks and also partly covered with sand waves; these two patterns can also overlap or both be absent. A theoretical morphodynamic approach has provided a model which gives two physical parameters (Stokes number and resistance parameter) discriminating between a flat bed, the growth of tidal sand banks, sand waves, both sand banks and sand waves and parallel ridges. This paper reports whether this bed pattern model is able to make correct predictions in the Southern North Sea. In order to judge the level of agreement both predictions as well as observations have to be treated at an aggregated level, the level of patches of patterns. This leads to the results that the order of magnitude of the predictions is correct, which means that for realistic values of the input parameters all types of observed patterns are indeed predicted in the North Sea. The predictions show patchy behaviour of patterns, like observed. For the major part of the observed patterns it has explicitly been shown that there are input parameters which are able to predict the local correct pattern. The present study shows that the presence of bed patterns can be, in a global way, predicted by the model. Due to the assumptions underlying this model this implies that the bed patterns in the Southern North Sea can be explained as the res ult of long-term bed-tide interactions.