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CHAPTER 10: Introduction to the Lithosphere

(ac). Coastal and Marine Processes and Landforms: Wave Refraction, Erosion, and Deposition

Wave Refraction, Erosion, and Deposition

Segments A and B at position 1 in the figure below are in deep water and are unchanged. By the time they have reached position 3, A has slowed down and shortened its wavelength. It therefore lags behind B which is still unchanged. By the time the wave reaches position 5, A is about to break on the headland while B is advancing more slowly into the bay. The end result is that the crests try to conform to the outline of the shore and to break parallel to it. Segments A and B in deep water were the same width. The orthogonals which are drawn at right angles to the crests from the ends of segments A and B show that the length of A is shortened by about 20 percent at its breaking point (position 5), and B is lengthened to more than twice its deep water value at its breaking point. This means that the wave energy in segment A is concentrated onto the headland which causes wave height to increase in addition to the wave heightening caused by the shallowing of the water. Thus, since wave energy is proportional to wave height, the power of the waves is greater on the headland. In the bay, wave height is less since the energy of segment B is spread out. As a result, headlands are usually sites of intense erosion while embayments are usually sites of sediment deposition. Given enough time wave erosion will tend to create a smooth coastline.

The following photograph shows the refraction of waves from above as they approach the shoreline.



Study Guide


Additional Readings

Internet Weblinks
Citation: Pidwirny, M. (2006). "Coastal and Marine Processes and Landforms: Wave Refraction, Erosion, and Deposition". Fundamentals of Physical Geography, 2nd Edition. Date Viewed.


Created by Dr. Michael Pidwirny & Scott Jones University of British Columbia Okanagan

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05/07/2009 9:54