MEASUREMENTS ON THE INTERACTION BETWEEN DUNES AND DIKES DURING EXTREME STORM EVENTS

This paper presents video-based measurements of morphological experiments in the Vinjé wave basin. The experiments were carried out to study effects of fixed structures on dune erosion. We developed a new measurement method based on video images, that successfully uses the differences between two succeeding images to derive detailed and accurate measurements of the bathymetry. We also developed a method to monitor the position of the dune crest during the experiments by using the variations of the color intensities along a cross-shore transect to determine the dune crest position. Measurements nicely represent the episodic collapsing dune front. The measurements also show an increased erosion near a connection between a dune and a dike compared to an undisturbed dune section. The additional amounts of dune erosion are larger at breaches in a dike and in a dune foot revetment.