Coves - artificial formation and use
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The formation of a cove can occur naturally (between to headlands) or artificially (between two coastal structures) and has specific functional characteristics. The cove concept is similar to the formation of pocket beaches, where ideally there is little or no exchange of sediment between the pocket beach and the adjacent shorelines. The cove concept is suited to coastlines that have an angle of incidence 10–50 degrees from the shore (0 degrees=shore normal). The formation of a cove can benefit an area by creating a recreational environment for both swimming and the beach-landing of small boats. There are however things to consider, if the cove opening is too narrow circulation will be reduced and the quality of the water will decrease and secondly the cove may trap debris and seaweed.
A pocket beach is normally a small beach between two headlands with little or no exchange of sediment with the adjacent shorelines. Many natural pocket beaches exist throughout the world and artificial pocket beaches are usually constructed in areas where natural beaches are fairly narrow or absent. These artificial pocket beaches will begin to form by themselves as soon as the structures have been built, however it is recommended to include initial beach fill in the design.
The formation and shape of a cove is fairly independent of the wave climate due to the relatively narrow opening. The cove concept is very similar to the pocket beaches, which are formed in the gaps of segmented breakwaters, with narrow gaps. It is important that there is a suitable distance from the coastline to the head of the structures in order to avoid dangerous currents, this distance should ideally be larger than the width of the littoral zone.
The cove concept is especially suited for coasts with oblique wave attack (type 3M and 3E coasts, see: Classification of sandy coastlines), and for locations with steep coastal profiles. This type of coast has a large littoral transport potential and is often exposed to erosion and will therefore in many cases already have been protected. Traditionally, this type of coast is protected by revetments, as it is difficult to apply an optimal shore protection system. Long sections of accumulated material upstream of protruding coastal structures cannot be used in this situation due to the oblique wave attack. This type of coast is normally unsuitable for artificial nourishment as a stand-alone measure, as this will result in large maintenance requirements. Nor will beach fill in connection with structures work, as the structures can only hold a short beach section due to the oblique wave exposure.
The small cove shown in Fig. 1 may change a small coastal section protected by a revetment into an attractive recreational environment. It is especially suited to provide a semi-protected beach at locations, which are too exposed for safe swimming. Such a semi-protected bay is also very suitable for beach-landing small fishing boats.
Although the cove concept is the optimal solution for type 3 coasts, the concept can also be used for all other types of coasts. It is also important to note that the opening to the cove should not be made too narrow, as this will reduce circulation and degrade the water quality. And that the cove may trap seaweed and debris, but the smooth shape of the structures will normally reduce this problem.
See also: Hard coastal protection structures
Mangor, K., Drønen, N. K., Kaergaard, K.H. and Kristensen, N.E. 2017. Shoreline management guidelines. DHI https://www.dhigroup.com/marine-water/ebook-shoreline-management-guidelines.
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