coast

A coast is the zone where land meets the sea. It includes the shoreline itself and an adjacent belt of land and sea in which marine processes shape the landscape. The term coast often overlaps with coastline, the line marking the interface, while 'coastal zone' is a broader area that extends inland and offshore where coastal processes dominate.

Coasts are formed and continually modified by waves, tides, currents, wind, and sea level fluctuations. Erosion wears away cliff and rock; transportation moves sediment; deposition builds beaches, spits, deltas, dunes. Landforms include cliffs, beaches, dunes, estuaries, deltas, and coral or rocky coasts depending on geology and energy regime.

Coastal ecosystems include intertidal zones, salt marshes, mangroves, seagrass beds, and coral reefs. They support high biodiversity and provide ecosystem services such as buffering storms, nurseries for fisheries, and water filtration. Human activity concentrates along coasts for ports, fisheries, tourism, and industry.

Coasts face hazards: coastal erosion, tropical cyclones, tsunamis, storm surges, sea-level rise. Climate change and human development alter sediment supply and coastal dynamics, increasing flood risk and shoreline retreat in many regions.

Coastal management aims to balance development with protection of natural resources. Approaches include hard engineering structures (sea walls, breakwaters), soft techniques (beach nourishment, dune restoration), and planning tools (zoning, protected areas). Integrated coastal zone management coordinates land-sea planning across jurisdictions.