Narrow Results

The nearshore hydrodynamic and morphological model CSHORE has been under development for the past several years, utilizing a multitude of laboratory data sets. Although the model has a physically-based foundation, all practical morphological models, including CSHORE require empirical parameters. The model is compared with a large set of field data and two representative examples are provided in detail. The storm response data sets, one from the east coast of the US and one from the west coast, are similar in bulk wave statistic but differ in that the East Coast case has a significant storm surge. The model performs reasonably well without site-specific calibration, but some improvement is realized by increasing the effect for the dissipation due to breaking waves on the West Coast.

In this paper we present the first results of beach profile hindcasting with XBeach using recently measured coastal data acquired under storm conditions at eight European sites, including a comparison to model results obtained with off-the-shelf models. The results show consistently that the XBeach has skill in predicting the coastal profile, albeit that in most cases the erosion around the mean water line is overpredicted and the depositions at the lower beach face are overpredicted. The causes for this model effect are under active investigation but not resolved yet. Likely candidates are the modeling of onshore (asymmetry) transports which reduces the offshore transports due to undertow (currents) or the modeling of sediment motion in the swash zone.

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.

Strong low-pressure systems traveled along Japanese Main Island in October 2006. High waves and storm surge attacked Kashima Coast resulting huge erosion over the area. The extent of the study area is 38 km long for the northern Kashima Coast and 15 km long for the southern Kashima Coast. This study analyzed the foreshore erosion caused by the storms using airborne laser data measured in October 2005 and November 2006. The results are compared with the distributions of longshore component of wave power and wave run-up which estimated using SWAN wave model. The results indicate that the amount of erosion and its distribution are in agreement with the longhsore component of the wave power along the coast and the most of the high wave run-up values appear within the high eroded sections. These were especially prominent at the untreated sections, which should be close to the natural response by wave action.