MAST200 Lecture Notes - Lecture 17: Longshore Drift, Dune, Refraction

• School: University of Delaware
• Department: Marine Studies
• Course: MAST200
• Professor: Thoroughgood Carolyn

Document Summary

Coastal zones and water circulation, beach structures and sand budgets, coastal dunes, barrier islands, tidal inlets, cliffed coasts and deltas, coastline formation, mitigation strategies. Breaking waves provide energy that changes the shape and texture of beach deposits. As waves shoal (touch bottom) in shallow water, celerity decreases, wave height increases, waves become less stable, refraction occurs. Wave refraction is bending of waves towards shallower water so that they break almost parallel to shore. Wave refraction and wave breaking depend on bottom depth and slope. Waves become unstable and break in very shallow water. Types of breaking waves: spilling, plunging, surging. Longshore currents transport sand parallel to shore. Beaches: part of the land that touches the sea. Waves, tides, and currents erode cliffs, wash away dunes and transport sand to and from the beach. Beaches function as a buffer that minimizes erosion by storm-driven ocean waves. Offshore zone: area seaward where waves first begin to break.