EAS205 Lecture Notes - Longshore Drift, Wave Base, United Service Organizations
8 May 2014
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Document Summary
Can be rapidly changing or relatively stable. Shoreline geometry is determined by plate tectonics: active margin, passive margin. Fairly deep drop to oceanic depths offshore. Extensive development of broad beaches, sandy offshore islands. Induced by the flow of wind across the water surface. Most approach shore at an oblique angle and are refracted: results in longshore current and longshore drift. Depth at which water motion is negligible: when wave crest velocity > velocity at base. Surf zone: region from the break zone to the swash zone, longshore current and longshore drift. Tend to be short-term and unstable features. Seasonal cycles with differing wave characteristics: offshore sandbars and double beaches in winter, but not there in the, low air pressure causes bulging in the water surface, and high winds, storm surges, tidal augmentation. Periodic, regional rise and fall in water levels due to gravitational pull of the. Swash zone: results in beach drift.
