Modeling wave and wind climate effects on tidal sand wave dynamics: A North Sea case study

Abstract

To obtain site-specific wave and wind climate averaged sand wave dynamics, we combine an idealized linear stability model with 20 years of wave and wind data taken from the Euro Platform in the North Sea. The model output results in a wave and wind climate-averaged growth and migration rate. The results show that waves and wind affect particularly migration and to a much smaller extent the growth rate. Seasonal variations in wave and wind conditions during winter and summer periods result in seasonal variations in sand wave dynamics, in particular during winter the migration rate is larger, the growth rates are lower and the preferred wavelength is larger compared to summer. Medium wave and wind conditions are responsible for two thirds of the migration rate, while these conditions occur roughly only one third of the time. Extreme wave and wind conditions result in only a moderate contribution to the migration rate. Furthermore, we see a seasonal variation in migration as well as reasonable correlation with observed migration rates for the intervals between surveys in the period 1996–2010. Our work shows that storms are able to affect sand wave migration, and cause variability in migration rate.