Data analysis of sand waves in the North Sea

Monitoring of the sand wave covered bathymetry near the entrance channel to Rotterdam harbour resulted in detailed information on the sand wave field. These data are analysed using a 2 dimensional spectral analysis. Here, the first results are presented. The surface has a very complex structure, which is however, nothing else than the result of three different waves. The smaller waves appear to be very sensitive to the presence of larger waves. The wavelength of the waves depends on the local water depth. This is in agreement with most theoretical models, which use a scaling with the depth to get a uniform wavelength. This dependency results in a number of different patterns, ranging from very complex 2 dimensional patterns to fairly regular sand waves with a sinusoidal crest.