9 - Coastal sand dunes
from Part III - Coastal Systems
Summary
Synopsis
Sandy beaches offer an exposed source of sediment and so almost all sandy beaches are fringed by some form of sand dune formed by sand transported by wind action and deposited in the vegetation landward of the beach. Dunes range from small forms less than a metre in height and a few metres in width and alongshore extent on small rocky embayments, to features that may be 100 m or more in height, extending for tens of km alongshore on sandy barrier systems or low coastal plains. Generally most of the sediment transported landward from the backshore is trapped initially by vegetation colonising the area just landward from the limit of storm wave action, leading to the development of a foredune ridge complex parallel to the shoreline. On some beaches, because of limited sediment availability or low frequency of strong onshore winds, only a single foredune complex will develop. However, in other areas where there is an abundant supply of sediment and sufficiently strong onshore winds, extensive dune fields may develop, either through inland migration of parabolic or long-walled transverse dunes, or through shoreline progradation and the formation of a succession of foredune ridges.
The area close to the beach is a zone of high stress for plants as a result of high temperatures near the bed, moisture deficit, exposure to salt spray, low nutrient supply and especially because of disturbance due to burial by sand transported by the wind and to the effects of wave action during storms.
- Type
- Chapter
- Information
- Introduction to Coastal Processes and Geomorphology , pp. 228 - 279Publisher: Cambridge University PressPrint publication year: 2009
References
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