Artificial physical structures

Coastal armouring occurs because of the construction of artificial structures along natural shorelines.These include revetments, docks, groynes and seawalls, in addition to numerous minor structures (Table 7.1). This coastal infrastructure not only provides important onshore functions, but also brings shipping onto the shoreline, facilitating loading and unloading. Structures running alongshore, such as revetments and seawalls, are often built to protect shorelines against erosion, or to provide easy access to ships. They are usually steep and constructed of material designed to withstand erosion and wear, and are placed above the high tide level, inter- or subtidally, or offshore. Other structures, built perpendicular to the shore, for example, groynes and jetties, are often built to prevent movement of sand, or to gain access to boats in deeper water. Structures such as drilling platforms and wind turbines have become common features in offshore waters. Dugan et al. (2011)provide a detailed summary of the types and extent of infrastructure common on many shores today.