A breakwater is a permanent structure constructed at a coastal area to protect against tides, currents, waves, and storm surges. Breakwaters have been built since Antiquity to protect anchorages, helping isolate vessels from marine hazards such as wind-driven waves. A breakwater, also known in some contexts as a jetty or a Mole, may be connected to land or freestanding, and may contain a walkway or road for vehicle access.
The Alamitos Bay, California, entrance channel. Breakwaters create safer harbours, but can also trap sediment moving along the coast.
Breakwater under construction in Ystad, Sweden (2019)
A breakwater in Haukilahti, Espoo, Finland
Barra da Tijuca – Rio de Janeiro
Coastal management is defence against flooding and erosion, and techniques that stop erosion to claim lands. Protection against rising sea levels in the 21st century is crucial, as sea level rise accelerates due to climate change. Changes in sea level damage beaches and coastal systems are expected to rise at an increasing rate, causing coastal sediments to be disturbed by tidal energy.
Oosterscheldekering sea wall, the Netherlands.
Groyne at Mundesley, Norfolk, UK
Cement beach reinforcements in on the coast of Alexandria, Egypt to prevent further erosion of coastline that is vulnerable to subsidence.
Figure 1. A diagram representing the spatial relationship between many of the commonly used indicators.