Coasts

A coast is the area where land meets the sea, and it is one of the most dynamic interfaces on Earth. Coasts are shaped by the actions of waves, tides, wind, and currents, as well as by sediment supply from rivers. They encompass a range of landforms and habitats, from beaches and dunes to cliffs, estuaries, and coastal wetlands.

Coastal processes involve erosion, transport, and deposition of materials. Waves incident at an angle move sediment along shore in a longshore current, while wave refraction concentrates energy against headlands. Sediments may be deposited to form beaches, spits, bars, tombolos, or deltas, and dunes or salt marshes can develop behind protective features.

Coasts vary in morphologies: sandy coasts with beaches and dunes; rocky coasts with cliffs and stacks; estuaries and deltas at river mouths; and tidal flats and mangrove or salt-marsh systems in sheltered zones.

Human settlements, industry, and recreation depend on coasts but also threaten them through development and pollution. Hazards include coastal erosion, flooding, and storm surges. Management options range from hard engineering (sea walls, groynes) to soft engineering (beach nourishment, managed retreat) and integrated coastal zone management.

Climate change is altering coastlines through sea-level rise and changing storm patterns, accelerating erosion in some areas and expanding others via sediment dynamics. Understanding coastal geomorphology and planning for resilience remain central to conserving ecosystems and safeguarding coastal communities.