Decadal-scale morphologic variability of foredunes subject to human interventions

Foredunes, the first row of dunes when viewed from the beach, fulfill an important task when it comes to protecting the hinterland against flooding from the sea. Due to climate related factors such as rising sea levels and an increase in extreme storm conditions, this task is under increasing pressure. As dunes are not static landscape features, but their form and position change through time, the level of safety they provide also changes through time. It is important to note that dunes that are essential in protecting the hinterland against flooding are mostly managed by man to secure a minimal level of safety. The present Coastal Policy (3e Kustnota, Ministerie van V&W (2000)) states that dunes should not only offer protection today, but also continue to do so in the coming 50 to 200 years. It appears that at a time period of decades to centuries, there is hardly any understanding on the form and position of coastal dunes that are subject to interventions. Therefore, the first objective of this study was to analyze the changes in shape of these dunes over a time period of approximately 50 years. For this time period, data is available from the so-called Jarkusdatabase (yearly coastal measurements), that show the yearly cross-shore development of the dunes.