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A mathematical model is formulated to describe incipient breaching of coastal barrier islands. The model is based on the assumptions of idealized breach morphology and is intended to describe the growth of breaches prior to possible closure by longshore sediment transport. The two coupled, non-linear equations governing breach width and depth are solved analytically for special cases. The analytical solutions explicitly exhibit an exponential behavior in breach dimensions and reveal that the macroscale process of breach growth is controlled by seven variables: initial width and depth of the breach, equilibrium width and depth of the breach, width of the barrier island, and maximum or initial net sediment transport rates at the bottom and sides of the breach. The literature is reviewed to compile general properties of coastal breaches, and sensitivity testing shows the model to be compatible with those observations. The model is applied to simulate the 1980 breach at Moriches Inlet, New York, and reasonable agreement is found.

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.