MEA 200 Lecture Notes - Lecture 21: Thermal Expansion, Coastal Erosion, Surf Zone
30 Mar 2017
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Document Summary
Swash water rushes up the beach. Backwash water drains back to the ocean. Longshore transport/drift transports sand along the beach. Transports beach sediment in a zigzag fashion in the direction of the longshore current. Longshore currents travel at speeds up to 4 km (2. 5 miles) per hour. Millions of tons of sediment moved yearly. Direction of transport changes due to wave approach. Sea levels around the world are rising. Current sea-level rise potentially affects human populations and the natural environment. 1950 to 2009 sea level rise of 1. 7 0. 3 mm per year. 1993 to 2009 sea level rise of 3. 3 0. 4 mm per year. In the last 20 years it has risen considerably faster than the last 100 years. Local tectonic processes raise or lower earth"s crust. Wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, drainage or high winds. Understanding coastal erosion is not as easy.
