Changes in the shoreline caused by coastal structures

A model is described that was designed to predict the shoreline changes due to the most widely distributed types of coastal structures such as groins, jetties, breakwaters, and access channels, which disturb the alongshore sediment fluxes. The key assumptions based on empirical data are related to the extension of the areas with the sediment excess and deficit. It is shown that the most important factors are, on the one hand, the size of the structure and the depth of its location and, on the other hand, the width of the alongshore sediment flux and the depth at its outer edge. The relations between these parameters determine the spatial scales of the morphology perturbations at a given coast. The temporal scale of the shoreline changes considered is restricted to the period a few years after the structure was built. The input data and the typical output results are illustrated by an example of calculations.