Sandbars migrate on average in offshore direction. They decay at a certain water depth and the released sediment is transported onshore to form a new bar, generating a continuous bar cycle. It is important to have detailed knowledge about sandbar behaviour, because morphodynamic changes in the future can then be predicted. There are already some models that predict bar behaviour relatively well, but the factors of influence that determine the duration of the bar cycles are not clear yet. For example, the duration of the bar cycles in Noordwijk and Egmond is about 4 and 15 years respectively, with conditions that are only slightly different. For example, the waves of Egmond are on average 20 cm larger and the near-shore profile until a water depth of 15 meter is steeper at Egmond.
Preliminary work, performed by E. van der Deijl (in 2013) showed already that it is probably the steeper near-shore zone of Egmond that causes the longer bar cycle duration. My research will focus more on this near-shore profile, to determine which part of the profile is mainly responsible for this. Is it the the steeper bar zone of Egmond, the steeper and higher bars, or is it the steeper offshore part of Egmond (offshore from the bar zone) that increases the bar cycle duration? I will also try to find morphological and hydrodynamical reasons for this. Why causes these different profiles a significant different bar-cycle duration?
A calibrated UNIBEST-TC model for Noordwijk is used for this research. This model is adapted for profile changes in order to find the answers of the research questions.
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