(K) Coastal Processes • Waves and associated currents are the principal forces behind change along coasts • Currents Friction drag by low-altitude winds on sea surface Convectional (e.g. due to salinity or temperature differences) • Waves In open, deep water, the water moves in circular orbits, relatively large near the surface and decreasing in diameter with increasing depth Wave base is the depth at which water motion and associated sediment transport are negligible When a wave begins to interact with the bottom (i.e. seabed), it develops into a breaker with water arches over Constructive waves: Offshore prevailing wind Destructive waves: Onshore prevailing wind • Beaches: Sediment transport at shorelines Sediment-laden waters deposit their load as they are slowed Wave refraction along an irregular coastline results in wave energy dissipation in recessed bays between projecting points of land Deposition occurs in bays; hence formation of beaches
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Sediment, Longshore drift, wave energy dissipation, irregular coastline results